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Stem Cell Research Center

Published Medical Research

Dental Stem Cells
03/04/2014 - Adhesion and Proliferation of Human Dental Pulp Stem Cells on Porous Silicon Scaffolds
Abstract

In regenerative medicine, stem-cell-based therapy often requires a scaffold to deliver cells and/or growth factors to the injured site. Porous silicon (pSi) is a promising biomaterial for tissue engineering as it is both nontoxic and bioresorbable. Moreover, surface modification can offer control over the degradation rate of pSi and can also promote cell adhesion. Dental pulp stem cells (DPSC) are pluripotent mesenchymal stem cells found within the teeth and constitute a readily source of stem cells. Thus, coupling the good proliferation and differentiation capacities of DPSC with the textural and chemical properties of the pSi substrates provides an interesting approach for therapeutic use. In this study, the behavior of human DPSC is analyzed on pSi substrates presenting pores of various sizes, 10 ± 2 nm, 36 ± 4 nm, and 1.0 ± 0.1 µm, and undergoing different chemical treatments, thermal oxidation, silanization with aminopropyltriethoxysilane (APTES), and hydrosilylation with undecenoic acid or semicarbazide. DPSC adhesion and proliferation were followed for up to 72 h by fluorescence microscopy, scanning electron microscopy (SEM), enzymatic activity assay, and BrdU assay for mitotic activity. Porous silicon with 36 nm pore size was found to offer the best adhesion and the fastest growth rate for DPSC compared to pSi comporting smaller pore size (10 nm) or larger pore size (1 µm), especially after silanization with APTES. Hydrosilylation with semicarbazide favored cell adhesion and proliferation, especially mitosis after cell adhesion, but such chemical modification has been found to led to a scaffold that is stable for only 24–48 h in culture medium. Thus, semicarbazide-treated pSi appeared to be an appropriate scaffold for stem cell adhesion and immediate in vivo transplantation, whereas APTES-treated pSi was found to be more suitable for long-term in vitro culture, for stem cell proliferation and differentiation.

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02/07/2014 - Human Dental Pulp Stem Cells Improve Hypoxic-Ischemic Brain Damage
Abstract

Objective To investigate the effect of intraventricular injection of human dental pulp stem cells (DPSCs) on hypoxic-ischemic brain damage (HIBD).

Methods Thirty-six neonatal animal models (postnatal day 7) were assigned to control, HIBD, or HIBD+DPSC groups (n = 12 each group). For induction of HIBD, models underwent left carotid artery ligation and were exposed to 8% to 10% oxygen for 2 h. Hoechst 33324-labeled human DPSCs were injected into the left lateral ventricle 3 days after HIBD. Behavioral assays were performed to assess hypoxic-ischemic encephalopathy (HIE), and on postnatal day 45, DPSC survival was assessed and expression of neural and glial markers was evaluated by immunohistochemistry and Western blot.

Results The HIBD group showed significant deficiencies compared to control on T-maze, radial water maze, and postural reflex tests, and the HIBD+DPSC group showed significant improvement on all behavioral tests. On postnatal day 45, Hoechst 33324-labeled DPSC nuclei were visible in the injected region and left cortex. Subsets of DPSCs showed immunostaining for neuronal (neuron-specific enolase [NSE], Nestin) and glial markers (glial fibrillary acidic protein [GFAP], O4). Significantly decreased staining/expression for NSE, GFAP, and O4 was found in the HBID group compared to control, and this was significantly increased in the HBID+DPSC group.

Conclusion Intraventricular injection of human DPSCs improves HIBD in neonatal rats.

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12/16/2013 - Isolation and characterization of human dental pulp derived stem cells
Background: Dental caries remains a major public health concern. Dental endodontics (root canal) therapy involves extirpating the dental pulp and replacing with inert materials. For severe tooth decay, it is the only available treatment; however, it fails to restore the biological functions and vitality of the dental tissues and may ultimately leads to tooth loss. To overcome these shortcomings, dental pulp stem cells (DPSCs) are being investigated as a novel prospective approach to regenerate the dental tissue. In this study, we isolated and purified DPSCs and characterized the purified cells.

Objectives: The aims of this study were as follows: (i) to rapidly extirpate dental pulp tissues from human third molar teeth under sterile conditions; (ii) to isolate, characterize, and purify a heterogeneous population of DPSCs using mesenchymal stem cell markers; (iii) to determine the ability of DPSCs to differentiate down an odontoblastic lineage.

Design: DPSCs were mechanically and chemically isolated from human impacted third molar teeth. Cells were expanded, passaged, and a heterogeneous population of DPSCs isolated using a cloning cylinder. DPSCs were characterized and purified by flow cytometry using the mesenchymal stem cell markers, STRO-1, CD44, and CD146. DPSCs were induced under two different odontogenic conditions comprising different concentrations of beta-glycerophosphate, and dexamethasone. DPSCs were analysed for morphology, proliferation potential, collagen formation, mineralization characteristics, and expression of the dentin-specific markers dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP-1), using immunohistochemistry.

Results: DPSCs were positive for the mesenchymal stem cell markers STRO-1, CD44, and CD146, although two populations of cells showed different levels of STRO-1 expression. Differentiated DPSCs (dDPSCs) demonstrated a significant increase in alkaline phosphatase concentration between days 14 and 21, while a similar increase in collagen deposition, mineralization, and calcification was also observed on day 28. The proliferation rate of dDPSCs decreased with time. Odontoblast characteristics of dDPSCs were observed, with increased expression of the dentin-specific markers DSPP and DMP-1.

Conclusions: This investigation demonstrated successful isolation of DPSCs and differentiation of DPSCs down an odontoblastic lineage, indicating that DPSCs represent a promising approval for the regeneration of lost dental tissues.

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11/18/2013 - Multilineage potential and proteomic profiling of human dental stem cells derived from a single donor.
Source

Department of Theriogenology and Biotechnology, College of Veterinary Medicine, Gyeongsang National University, Jinju 660-701, Republic of Korea.

Abstract

Dental tissues provide an alternative autologous source of mesenchymal stem cells (MSCs) for regenerative medicine. In this study, we isolated human dental MSCs of follicle, pulp and papilla tissue from a single donor tooth after impacted third molar extraction by excluding the individual differences. We then compared the morphology, proliferation rate, expression of MSC-specific and pluripotency markers, and in vitro differentiation ability into osteoblasts, adipocytes, chondrocytes and functional hepatocyte-like cells (HLCs). Finally, we analyzed the protein expression profiles of undifferentiated dental MSCs using 2DE coupled with MALDI-TOF-MS. Three types of dental MSCs largely shared similar morphology, proliferation potential, expression of surface markers and pluripotent transcription factors, and differentiation ability into osteoblasts, adipocytes, and chondrocytes. Upon hepatogenic induction, all MSCs were transdifferentiated into functional HLCs, and acquired hepatocyte functions by showing their ability for glycogen storage and urea production. Based on the proteome profiling results, we identified nineteen proteins either found commonly or differentially expressed among the three types of dentalMSCs. In conclusion, three kinds of dental MSCs from a single donor tooth possessed largely similar cellular properties and multilineage potential. Further, these dental MSCs had similar proteomic profiles, suggesting their interchangeable applications for basic research and cell therapy.

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01/27/2013 - Stem cells in the face: tooth regeneration and beyond.
The face distinguishes one person from another. Postnatal orofacial tissues harbor rare cells that exhibit stem cell properties. Despite unmet clinical needs for reconstruction of tissues lost in congenital anomalies, infections, trauma, or tumor resection, how orofacial stem/progenitor cells contribute to tissue development, pathogenesis, and regeneration is largely obscure. This perspective article critically analyzes the current status of our understanding of orofacial stem/progenitor cells, identifies gaps in our knowledge, and highlights pathways for the development of regenerative therapies. Stem Cells in Face: Tooth Regeneration Full Text
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07/24/2012 - In vitro analysis of mesenchymal stem cells derived from human teeth and bone marrow
Mesenchymal stem cells derived from human teeth and bone marrow have been characterized by many research groups, but demonstrate inconsistent cellular phenotypes or functions, partly because of differences in culture methodology. Therefore, our aims were to resolve these inconsistencies and discuss the potential uses of these cells in research/clinical applications. We isolated and characterized dental stem cells (DSCs) from the dental pulp, periodontal ligament, apical papilla (APSCs) and dental follicle (DFSCs) of mature and immature teeth, along with bone marrow-derived stem cells (BMSCs) from the iliac crest. We compared the clonogenic and proliferative potentials of these cells in terms of colony-forming efficiency, proliferation potential, population doubling time and cell cycle. All DSCs, particularly APSCs and DFSCs, possessed greater proliferative potential than BMSCs. All stem cells expressed typical mesenchymal and embryonic markers, and developed alizarin red-positive mineralization nodules and Oil red O-positive lipid droplets when cultured in osteogenic and adipogenic media, respectively. Immunocytochemistry revealed that all stem cells developed neuronal markers when cultured in a control medium without neural inductive supplements. After 7 days of neurogenic culture, the differentiated cells showed a transition from fibroblast-like to neuron-like cell bodies with long processes, suggesting that the stem cells differentiated into mature neurons. Karyotyping confirmed that the stem cells maintained a normal karyotype and were chromosomally stable. Our results provide new insights into the physiological properties of stem cells with a normal karyotype and indicate that DSCs are appropriate for basic research and clinical applications.

To view the full research, click here.

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07/11/2012 - Scaling-Up of Dental Pulp Stem Cells Isolated from Multiple Niches
Dental pulp (DP) can be extracted from child’s primary teeth (deciduous), whose loss occurs spontaneously by about 5 to 12 years. Thus, DP presents an easy accessible source of stem cells without ethical concerns. Substantial quantities of stem cells of an excellent quality and at early (2–5) passages are necessary for clinical use, which currently is a problem for use of adult stem cells. Herein, DPs were cultured generating stem cells at least during six months through multiple mechanical transfers into a new culture dish every 3–4 days. We compared stem cells isolated from the same DP before (early population, EP) and six months after several mechanical transfers (late population, LP). No changes, in both EP and LP, were observed in morphology, expression of stem cells markers (nestin, vimentin, fibronectin, SH2, SH3 and Oct3/4), chondrogenic and myogenic differentiation potential, even after cryopreservation. Six hours after DP extraction and in vitro plating, rare 5-bromo-2'-deoxyuridine (BrdU) positive cells were observed in pulp central part. After 72 hours, BrdU positive cells increased in number and were found in DP periphery, thus originating a multicellular population of stem cells of high purity. Multiple stem cell niches were identified in different zones of DP, because abundant expression of nestin, vimentin and Oct3/4 proteins was observed, while STRO-1 protein localization was restricted to perivascular niche. Our finding is of importance for the future of stem cell therapies, providing scaling-up of stem cells at early passages with minimum risk of losing their “stemness”.

To view the full research, click here.

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03/09/2012 - Researchers Differentiate Dental Pulp Stem Cells into Liver Cells
Researchers from Nippon Dental University, Japan, have developed a method to boost the ability of dental stem cells to differentiate into hepatic (liver) cells.  The protocols developed by the researchers produced hepatic cells [from dental stem cells] in significantly high numbers and purity. The research demonstrates that stem cells from teeth are a reliable source of adult stem cell for future liver-cell therapies.

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02/29/2012 - Dental Pulp Stem Cells Restore Movement in Spinal Cord Injuries

Researchers at the Nagoya University Graduate School of Medicine in Japan are exploiting the neural capabilities of dental pulp stem cells obtained from human wisdom teeth. In the study, researchers used stem cells recovered from wisdom teeth to treat a rat population with transected spinal cords. The rats were found to have recovered locomotive function in their hind legs and regenerated damaged nerve cells and oligodendrocytes. In a parallel study, stem cells from bone marrow and skin fibroblasts were utilized with statistically significantly lesser effect.

As the study demonstrates, teeth are a valuable source of powerful stem cells. Banking your own adult stem cells today will insure your future health as regenerative therapies, such as these, are developed to treat a wide array of disease, trauma and injury.

To view the full article, click here.

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01/04/2012 - Differentiation of dental pulp stem cells into islet-like aggregates.
The post-natal dental pulp tissue contains a population of multipotent mesenchymal progenitor cells known as dental pulp stromal/stem cells (DPSCs), with high proliferative potential for self-renewal. In this investigation, we explored the potential of DPSCs to differentiate into pancreatic cell lineage resembling islet-like cell aggregates (ICAs). We isolated, propagated, and characterized DPSCs and demonstrated that these could be differentiated into adipogenic, chondrogenic, and osteogenic lineage upon exposure to an appropriate cocktail of differentiating agents. Using a three-step protocol reported previously by our group, we succeeded in obtaining ICAs from DPSCs. The identity of ICAs was confirmed as islets by dithiozone-positive staining, as well as by expression of C-peptide, Pdx-1, Pax4, Pax6, Ngn3, and Isl-1. There were several-fold up-regulations of these transcription factors proportional to days of differentiation as compared with undifferentiated DPSCs. Day 10 ICAs released insulin and C-peptide in a glucose-dependent manner, exhibiting in vitro functionality. Our results demonstrated for the first time that DPSCs could be differentiated into pancreatic cell lineage and offer an unconventional and non-controversial source of human tissue that could be used for autologous stem cell therapy in diabetes.

Source - Stempeutics Research Malaysia Sdn Bhd, (773817-K), Lot G-E-2A, Enterprise 4, Technology Park Malaysia, Bukit Jalil, 57000 Kuala Lumpur, Malaysia.
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12/06/2011 - Dental Stem Cells Promote Spinal Cord Regeneration After Injury
Recently, a team of researchers at the Nagoya University Graduate School of Medicine, motivated by the knowledge that stem cells taken from tooth pulp are capable of stimulating long-term regeneration of nerves in damaged spinal cords, tested the ability of dental stem cells to treat said injuries. The results have positively demonstrated that dental stem cells not only “promoted the   regeneration of transected axons by directly inhibiting multiple axon growth inhibitors,” but also, “prevented a damage-induced apoptosis,” and were able to replaced the original cells that were lost due to injury.

“To our knowledge, the latter two neuroregenerative activities are unique to tooth-derived stem cells and are not exhibited by any other previously described stem cells,” the researchers stated. “We propose that tooth-derived stem cells may be an excellent and practical cellular resource for the treatment of SCI [spinal cord injury].”

The era of regenerative medicine is now.

To read the full article click here.
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11/13/2011 - Stem cells in dental pulp of deciduous teeth
Dental pulp from deciduous (baby) teeth, which are discarded after exfoliation, represents an advantageous source of young stem cells. Herein, we discuss the methods of Deciduous Teeth Stem Cells (DTSCs) isolation and cultivation. We show that based on these methods, at least three different stem cells populations can be identified: a population similar to bone marrow derived mesenchymal stem cells (BM-MSCs), an epithelial stem-like cells (ESCs) and/or a mixed population composed of both cell types. We analyzed the embryonic origin and stem cell niche of DTSCs with respect to the advantages they can provide for their future use in cell therapies and regenerative medicine. In vitro and in vivo differentiation of the DTSCs populations, their developmental potential, immunological compatibility, tissues engineering, transplantation use in studies in animal models are also the focus of the present report. We briefly describe the derivation of induced pluripotent stem (iPS) cells from DTSCs, which can be obtained more easily and efficiently in comparison with human fibroblasts. These iPS cells represent an interesting model for the investigation of pediatric diseases and disorders. The importance of DTSCs banking is also discussed.

Butantan, Genetics, av. Vital Brasil, 1500, São Paulo, Brazil, 05503-900, 55 11 3726 7222; ikerkis@butantan.gov.br.

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10/28/2011 - Human dental pulp cells: a new source of cell therapy in a mouse model of compressive spinal cord injury.
J Neurotrauma. 2011 Sep;28(9):1939-49. Epub 2011 Aug 8.

Programa de Pesquisa em Neurociência Básica e Clínica, Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Brazil.

Strategies aimed at improving spinal cord regeneration after trauma are still challenging neurologists and neuroscientists throughout the world. Many cell-based therapies have been tested, with limited success in terms of functional outcome. In this study, we investigated the effects of human dental pulp cells (HDPCs) in a mouse model of compressive spinal cord injury (SCI). These cells present some advantages, such as the ease of the extraction process, and expression of trophic factors and embryonic markers from both ecto-mesenchymal and mesenchymal components. Young adult female C57/BL6 mice were subjected to laminectomy at T9 and compression of the spinal cord with a vascular clip for 1?min. The cells were transplanted 7 days or 28 days after the lesion, in order to compare the recovery when treatment is applied in a subacute or chronic phase. We performed quantitative analyses of white-matter preservation, trophic-factor expression and quantification, and ultrastructural and functional analysis. Our results for the HDPC-transplanted animals showed better white-matter preservation than the DMEM groups, higher levels of trophic-factor expression in the tissue, better tissue organization, and the presence of many axons being myelinated by either Schwann cells or oligodendrocytes, in addition to the presence of some healthy-appearing intact neurons with synapse contacts on their cell bodies. We also demonstrated that HDPCs were able to express some glial markers such as GFAP and S-100. The functional analysis also showed locomotor improvement in these animals. Based on these findings, we propose that HDPCs may be feasible candidates for therapeutic intervention after SCI and central nervous system disorders in humans.

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10/28/2011 - Feeder-free derivation of induced pluripotent stem cells from human immature dental pulp stem cells.
Cell Transplant. 2011 Apr 1.


Induced pluripotent stem cells (iPSC) can be created by forcing expression of certain genes in fibroblasts or other somatic cell types, reversing them to a pluripotent state similar to that of embryonic stem cells (ESC). Here, we used human immature dental pulp stem cells (hIDPSC) as an alternative source for creating iPSC. HIDPSC can be easily isolated from accessible tissue of young and adult patients. HIDPSC possess a fibroblast-like morphology, retaining characteristics of adult multipotent stem cells. Reprogramming of hIDPSC was fast, producing primary hIDPSC-iPSC colonies even under feeder-free conditions. hIDPSC acquired ESC-like morphology, expressed pluripotent markers, possessed stable, normal karyotypes and demonstrate the ability to differentiated in vitro and in vivo. Our data demonstrate that hIDPSC-iPSC offer an advantageous cell system for future cell therapy and basic studies, particularly as a model for pediatric developmental disorders.

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09/03/2011 - Human dental pulp stem cells demonstrate better neural and epithelial stem cell properties than bone marrow-derived mesenchymal stem cells.

Department of Stem Cell, Center for Stem Cell and Gene Therapies Research and Practice, Institute of Health Sciences, Kocaeli University, 41380, Kocaeli, Turkey, ekaraoz@hotmail.com.

Dental pulp stem cells (hDP-SCs) were primarily derived from pulp tissues of primary incisors, exfoliated deciduous and permanent third molar teeth. To understand the characteristics of hDP-SCs from impacted third molar, proliferation capacities, gene expression profiles, phenotypic, ultrastructural, and differentiation characteristics were analyzed in comparison with human bone marrow-derived mesenchymal stem cells (hBM-MSCs), extensively. hDP-SCs showed more developed and metabolically active cells. Contrary to hBM-MSCs, hDP-SCs strongly expressed both cytokeratin (CK)-18 and -19, which could involve in odontoblast differentiation and dentine repair. The intrinsic neuro-glia characteristics of hDP-MSCs were demonstrated by the expression of several specific transcripts and proteins of neural stem cell and neurons. These cells not only differentiate into adipogenic, osteogenic, and chondrogenic lineage, but also share some special characteristics of expressing some neural stem cell and epithelial markers. Under defined conditions, hDP-SCs are able to differentiate into both neural and vascular endothelial cells in vitro. Dental pulp might provide an alternative source for human MSCs. hDP-SCs with a promising differentiation capacity could be easily isolated, and possible clinical use could be developed for neurodegenerative and oral diseases in the future.

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07/30/2011 - Differentiation and Neuro-Protective Properties of Immortalized Human Tooth Germ Stem Cells.
Neurochem Res. 2011 Jul 22.

Department of Genetics and BioEngineering, College of Engineering and Architecture, Yeditepe University, 26 Agustos Campus, Kayisdagi cad, Kayisdagi, 34755, Istanbul, Turkey.

Stem cells are considered to be promising therapeutic options in many neuro-degenerative diseases and injuries to the central nervous system, including brain ischemia and spinal cord trauma. Apart from the gold standard embryonic and mesenchymal origin, human tooth germ stem cells (hTGSCs) have also been shown to enjoy the characteristics of mesenchymal stem cells (MSCs) and the ability to differentiate into adipo-, chondro-, osteo- and neuro-genic cells, suggesting that they might serve as potential alternatives in the cellular therapy of various maladies. Immortalization of stem cells may be useful to avoid senescence of stem cells and to increase their proliferation potential without altering their natural characteristics. This study evaluated the expression of stem cell markers, surface antigens, differentiation capacity, and karyotype of hTGSCs that have been immortalized by human telomerase reverse transcriptase (hTERT) or simian vacuolating virus 40 (SV40) large T antigen. These undying cells were also evaluated for their neuro-protective potential using an in vitro SH-SY5Y neuro-blastoma model treated with hydrogen-peroxide or doxo-rubicin. Although hTGSC-SV40 showed abnormal karyotypes, our results suggest that hTGSC-hTERT preserve their MSC characteristics, differentiation capacity and normal karyotype, and they also possess high proliferation rate and neuro-protective effects even at great passage numbers. These peculiars indicate that hTGSC-hTERT could be used as a viable model for studying adipo-, osteo-, odonto- and neuro-genesis, as well as neuro-protection of MSCs, which may serve as a springboard for potentially utilizing dental waste material in cellular therapy.

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07/30/2011 - Isolation of pluripotent stem cells from human third molar dental pulp.
Histol Histopathol. 2011 Aug;26(8):1057-70.

Regenerative Medicine Laboratory, Universitat Internacional de Catalunya, Barcelona, Spain.

Potent stem/progenitor cells have been isolated from normal human dental pulps, termed dental pulp stem cells (DPSCs). However, no study has described the presence of stem cell populations in human dental pulp from the third molar with embryonic phenotypes. The dental pulp tissue was cultured in media with the presence of LIF, EGF, and PDGF. In the present study, we describe a new population of pluripotent stem cells that were isolated from dental pulp (DPPSC). These cells are SSEA-4+, Oct4+, Nanog+, FLK-1+, HNF3beta+, Nestin+, Sox2+, Lin28+, c-Myc+, CD13+, CD105+, CD34-, CD45-, CD90low, CD29+, CD73low, STRO-1low and CD146-. We have investigated by SEM analysis and q-RT-PCR the capacity of DPPSCs to 3D differentiate in vitro using the Cell Carrier 3D glass scaffold into tissues that have similar characteristics to embryonic mesoderm and endoderm layers. These data would support the use of these cells, which are derived from an easily accessible source and can be used in future regeneration protocols for many tissue types that differentiate from the three embryonic layers.

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07/30/2011 - Induced in vitro differentiation of neural-like cells from human exfoliated deciduous teeth-derived stem cells.
Int J Dev Biol. 2011;55(2):189-95.

Pediatric Department, School of Dentistry, 2Department of Anatomical Sciences, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.

Stem cells from human exfoliated deciduous teeth (SHED) are highly proliferative, clonogenic and multipotent stem cells with a neural crest cell origin. Additionally, they can be collected with minimal invasiveness in comparison with other sources of mesenchymal stem cells (MSCs). Therefore, SHED could be a desirable option for potential therapeutic applications. In this study, SHEDs were established from enzyme-disaggregated deciduous dental pulp obtained from 6 to 9 year-old children. The cells had typical fibroblastoid morphology and expressed antigens characteristic of MSCs, STRO1, CD146, CD45, CD90, CD106 and CD166, but not the hematopoietic and endothelial markers, CD34 and CD31, as assessed by FACS analysis. Differentiation assessment revealed a strong osteogenic and adipogenic potential of SHEDs. In order to further evaluate the in vitro differentiation potential of SHED into neural cells, a simple short time growth factor-mediated induction was used. Immunofluorescence staining and flow cytometric analysis revealed that SHED rapidly expressed nestin and b-III tubulin, and later expressed intermediate neural markers. In addition, the intensity and percentages of nestin and b-III tubulin and mature neural markers (PSA-NCAM, NeuN, Tau, TH, or GFAP) increased significantly following treatment. Moreover, RT-PCR and Western blot analyses showed that the neural markers were strongly up-regulated after induction. In conclusion, these results provide evidence that SHED can differentiate into neural cells by the expression of a comprehensive set of genes and proteins that define neural-like cells in vitro. SHED cells might be considered as new candidates for the autologous transplantation of a wide variety of neurological diseases and neurotraumatic injuries.

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07/30/2011 - Pulp tissue from primary teeth: new source of stem cells.
J Appl Oral Sci. 2011 May-Jun;19(3):189-94.

Department of Community Dentistry and Pediatric Dentistry, Dental School, Federal University of Bahia, Salvador, BA, Brazil. p-telles@uol.com.br

SHED (stem cells from human exfoliated deciduous teeth) represent a population of postnatal stem cells capable of extensive proliferation and multipotential differentiation. Primary teeth may be an ideal source of postnatal stem cells to regenerate tooth structures and bone, and possibly to treat neural tissue injury or degenerative diseases. SHED are highly proliferative cells derived from an accessible tissue source, and therefore hold potential for providing enough cells for clinical applications. In this review, we describe the current knowledge about dental pulp stem cells and discuss tissue engineering approaches that use SHED to replace irreversibly inflamed or necrotic pulps with a healthy and functionally competent tissue that is capable of forming new dentin.

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05/01/2011 - Dual origin of mesenchymal stem cells contributing to organ growth and repair.
Proc Natl Acad Sci U S A. 2011 Apr 19;108(16):6503-8. Epub 2011 Apr 4.

Department of Craniofacial Development and Comprehensive Biomedical Research Centre, Dental Institute, Kings College London, London SE1 9RT, United Kingdom.

In many adult tissues, mesenchymal stem cells (MSCs) are closely associated with perivascular niches and coexpress many markers in common with pericytes. The ability of pericytes to act as MSCs, however, remains controversial. By using genetic lineage tracing, we show that some pericytes differentiate into specialized tooth mesenchyme-derived cells-odontoblasts-during tooth growth and in response to damage in vivo. As the pericyte-derived mesenchymal cell contribution to odontoblast differentiation does not account for all cell differentiation, we identify an additional source of cells with MSC-like properties that are stimulated to migrate toward areas of tissue damage and differentiate into odontoblasts. Thus, although pericytes are capable of acting as a source of MSCs and differentiating into cells of mesenchymal origin, they do so alongside other MSCs of a nonpericyte origin. This study identifies a dual origin of MSCs in a single tissue and suggests that the pericyte contribution to MSC-derived mesenchymal cells in any given tissue is variable and possibly dependent on the extent of the vascularity.

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03/08/2011 - 03/08/2011 - Type 1 diabetes stem cell treatment advances utilizing autologous dental stem cells
by Doctor Dharmini Pathmanathan, DMD, PhD

Diabetes is a chronic degenerative disease of the beta-cells of the pancreas leading to a lifelong dependency on insulin treatments.  While the cure for diabetes would be transplantation of cadaveric pancreatic islet cells to the diabetic individual, the scarcity of transplantable organs and side effects arising from a lifelong immunosuppressive regimen limits its therapeutic potential and is thus far from an ideal option. Similarly, the use of embryonic stem cells (ES), a favored option due to enormous differentiation potential of ES, is limited in its application in regenerative medicine because of persistent ethical and legal concerns. Thus, mesenchymal stem cells (MSCs) have been extensively studied for their ability to differentiate into insulin-producing cells. However, limited sources and the invasive procedures necessary to procure these cells restrict their application.  Given the limitations of the above procedures, locating a source of MSCs that is readily available and accessible and without any significant donor morbidity would be an ideal solution. Recent article in the Journal of Dental Research presented a benchmark study in which dental pulp stem cells (DPSCs) were differentiated into functional pancreatic cells. DPSCs were isolated from deciduous teeth that were already planned for serial extraction as part of orthodontic management. In short, the DPSCs were differentiated to islet-like cell aggregates (ICAs) using various growth factors and their identity confirmed using expression studies. In vitro functional studies showing that the DPSCs differentiated into ICAs could indeed respond to a glucose challenge with insulin production provided further confirmation for their potential use in islet transplantation programs. These findings add to the body of evidence regarding DPSCs ability to be differentiated into pancreatic cell lineage and their potential as a source of human tissue that could be used for an autologous stem cell therapy for diabetes without fear of rejection. Since DPSCs do not have the same restrictions as ES, are readily accessible, can be harvested from the individual himself, and virtually eliminate the possibility of rejection and therefore the use of immunosuppressants, DPSCs are considered to be an ideal source for MSCs for emerging diabetes stem cell treatments. Beyond diabetes, these findings also validate and encourage the banking of dental pulp stem cells for use in autologous stem cell therapy.  

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03/07/2011 - Vascular endothelial growth factor enhances in vitro proliferation and osteogenic differentiation of human dental pulp stem cells.

J Biol Regul Homeost Agents. 2011 Jan-Mar;25(1):57-69.

D' Alimonte I, Nargi E, Mastrangelo F, Falco G, Lanuti P, Marchisio M, Miscia S, Robuffo I, Capogreco M, Buccella S, Caputi S, Caciagli F, Tetè S, Ciccarelli R.

Departments of Biomedical Sciences, University of Chieti, Italy

Mesenchymal stem cells (MSC), isolated from dental tissues, are largely studied for future application in regenerative dentistry. In this study, we used MSC obtained from human dental pulp (DPSC) of normal impacted third molars that, when cultured in lineage-specific inducing media, differentiate into osteoblasts and adipocytes (evaluated by Alizarin Red S and Red Oil O stainings, respectively), thus showing a multipotency. We confirmed that DPSC, grown under undifferentiating conditions, are negative for hematopoietic (CD45, CD31, CD34, CD144) and positive for mesenchymal (CD29, CD90, CD105, CD166, CD146, STRO-1) markers, that underwent down-regulation when cells were grown in osteogenic medium for 3 weeks. In this condition, they also exhibit an increase in the expression of osteogenic markers (RUNX-2, alkaline phosphatase) and extracellular calcium deposition, whereas the expression of receptors (VEGFR-1 and -2) for vascular endothelial growth factors (VEGF) and related VEGF binding proteins was similar to that found in undifferentiated DPSC. Exposure of DPSC growing under undifferentiating or osteogenic conditions to VEGF-A165 peptide (10-40 ng/ml) for 8 days dose- and time-dependently increased the number of proliferating cells without inducing differentiation towards endothelial lineage, as evaluated by the lack of expression of specific markers (CD31, CD34, CD144). Additionally, exposure of DPSC cultured in osteogenic medium to VEGF-A165 for a similar period enhanced cell differentiation towards osteoblasts as evaluated after 14 and 21 days by Alizarin Red S staining and alkaline phosphatase activity quantification. These findings may have clinical implications possibly facilitating tissue repair and remodeling.

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03/07/2011 - Comparative Analysis of Telomere Length, Telomerase and Reverse Transcriptase Activity in Human Dental Stem Cells.

Cell Transplant. 2011 Mar 8.

Byeong GJ, Kang EJ, Kumar BM, Maeng GH, Ock SA, Kwack DO, Park BW, Rho GJ.

Stem cells from dental tissues have been isolated and established for tooth regenerative applications. However, basic characterization on their biological properties still needs to be investigated before employing them for effective clinical trials. In this study, we compared the telomere length, relative telomerase activity ( RTA) and relative reverse transcriptase activity ( RRA) as well as the surface antigen profile and mesenchymal differentiation ability in human dental papilla stem cells ( DPaSCs) , dental pulp stem cells ( DPuSCs) and dental follicle stem cells ( DFSCs) with mesenchymal stem cells ( MSCs) derived from bone marrow. Dental stem cells ( DSCs) were strongly positive for cell surface markers, such as CD44 and CD90. However, slightly lower expression of CD105 was observed in DPaSCs and DPuSCs compared to DFSCs and MSCs. Following specific induction, DPaSCs, DFSCs and MSCs were successfully differentiated into adipocytes and osteocytes. However, DPuSCS, in particular, were able to differentiate into adipocytes but failed to induce into osteogenic differentiation. Further, all DSCs, MSCs, and MRC- 5 fibroblasts as control were investigated for telomere length by non- radioactive chemiluminescent assay, RTA by relative- quantitative telomerase repeat amplification protocol ( RQ- TRAP) , and RRA by PCR- based assay. Mean telomere lengths in DPaSCs, DPuSCs, DFSCs and MSCs was '11 kb, and the values did not differ significantly (P<0.05) among the cells analyzed. RTA levels in DPaSCs were significantly ( P<0. 05) higher than in MSCs, DPuSCs, DFSCs, and MRC- 5 fibroblasts and among DSCs, DFSCs showed a significantly ( P<0. 05) lower RTA. Moreover, RRA levels were significantly ( P<0. 05) higher in DPaSCs, DPuSCs and MSCs than in DFSCs. Based on these observations, we conclude that among DSCs, DPaSCs possessed ideal characteristics on telomere length, telomerase activity and reverse transcriptase ( RTase) activity, and may serve as suitable alternative candidates for regenerative medicine.

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03/01/2011 - Biomaterials coated by dental pulp cells as substrate for neural stem cell differentiation.
Abstract
This study is focused on the development of an in vitro hybrid system, consisting in a polymeric biomaterial covered by a dental pulp cellular stroma that acts as a scaffold offering a neurotrophic support for the subsequent survival and differentiation of neural stem cells. In the first place, the behavior of dental pulp stroma on the polymeric biomaterial based on ethyl acrylate and hydroxy ethyl acrylate copolymer was studied. For this purpose, cells from normal human third molars were grown onto 0.5-mm-diameter biomaterial discs. After cell culture, quantification of neurotrophic factors generated by the stromal cells was performed by means of an ELISA assay. In the second place, survival and differentiation of adult murine neural stem cells on the polymeric biomaterials covered by dental pulp stromal cells was studied. The results show the capacity of dental pulp cells to uniformly coat the majority of the material's surface and to secrete neurotrophic factors that become crucial for a subsequent differentiation of neural stem cells. The use of stromal cells cultured on scaffolding biomaterials provides neurotrophic pumps that may suggest new criteria for the design of cell therapy experiments in animal models to assist the repair of lesions in Central Nervous System. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011J Biomed Mater Res A. 2011 Feb 11. doi: 10.1002/jbm.a.33032. [Epub ahead of print]

Soria JM, Sancho-Tello M, Esparza MA, Mirabet V, Bagan JV, Monleón M, Carda C.

Facultad Ciencias de la Salud, Universidad CEU Cardenal Herrera, Avda Seminario sn. 46113 Moncada, Valencia, Spain. jose.soria@uch.ceu.es.

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01/25/2011 - Dental Stem Cells to regrow and repair Salivary Glands.
By Doctor Dharmini Pathmanathan, DMD, PhD
 
Doctor Xing Yan, has been awarded a grant from the National Natural Science Foundation of China in the field of salivary gland regeneration utilizing dental stem cells.  Dr. Yan will collaborate with Dr. George Huang, a StemSave Scientific Advisor on this important research project.  The purpose of the research is to study the functional regeneration of salivary glands, specifically the parotid glands damaged by radiation, using induced pluripotent stem (iPS) cells reprogrammed from dental pulp stem cells. Salivary gland stem cells and iPS cells differentiated into salivary gland cells will be isolated and using animal models will be tested for their ability to regenerate a functional salivary gland. 
 
While primary salivary gland tumors are rare, surgical and radiation treatments can have adverse consequences to salivary gland function. Annually, about  40,000 individuals are affected by radiation damage to the salivary glands secondary to head and neck cancer radiation therapy. Salivary gland hypofunction significantly compromises the quality of life of those individuals through poor oral health and neglect and non-compliance of drug treatments that reduce salivary flow. Options for those who suffer from salivary hypofunction are limited and at best palliative. Therefore, studies by Drs. Huang and Yan using dental stem cells to regenerate functional salivary glands are at the scientific forefront of finding real solutions to millions affected by poor salivary function.
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01/24/2011 - Human dental pulp stem cells produce mineralized matrix in 2D and 3D cultures.

Eur J Histochem. 2010 Nov 10;54(4):e46.

Riccio M, Resca E, Maraldi T, Pisciotta A, Ferrari A, Bruzzesi G, De Pol A.

Dept. Anatomy and Histology, University of Modena and Reggio Emilia. massimo.riccio@unimore.it.

The aim of this study was to characterize the in vitro osteogenic differentiation of dental pulp stem cells (DPSCs) in 2D cultures and 3D biomaterials. DPSCs, separated from dental pulp by enzymatic digestion, and isolated by magnetic cell sorting were differentiated toward osteogenic lineage on 2D surface by using an osteogenic medium. During the differentiation process, DPSCs express specific bone proteins like Runx-2, Osx, OPN and OCN with a sequential expression, analogous to those occurring during osteoblast differentiation, and produce extracellular calcium deposits. In order to differentiate cells in a 3D space that mimes the physiological environment, DPSCs were cultured in two distinct bioscaffolds, MatrigelTM and Collagen sponge. With the addition of a third dimension, osteogenic differentiation and mineralized extracellular matrix production significantly improved. In particular, in MatrigelTM DPSCs differentiated with osteoblast/osteocyte characteristics and connected by gap junction, and therefore formed calcified nodules with a 3D intercellular network. Furthermore, DPSCs differentiated in collagen sponge actively secrete human type I collagen micro-fibrils and form calcified matrix containing trabecular-like structures. These neo-formed DPSCs-scaffold devices may be used in regenerative surgical applications in order to resolve pathologies and traumas characterized by critical size bone defects.

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01/24/2011 - Integration of neuronally predifferentiated human dental pulp stem cells into rat brain in vivo.

Neurochem Int. 2011 Jan 8.

Király M, Kádár K, Horváthy DB, Nardai P, Rácz GZ, Lacza Z, Varga G, Gerber G.

Department of Oral Biology, Semmelweis University, Nagyvarad ter 4, 1089 Budapest, Hungary.

Abstract

Pluripotency and their neural crest origin make dental pulp stem cells (DPSCs) an attractive donor source for neuronal cell replacement. Despite recent encouraging results in this field, little is known about the integration of transplanted DPSC derived neuronal pecursors into the central nervous system. To address this issue, NFneuronally predifferentiated DPSCs, labeled with a vital cell dye Vybrant DiD were introduced into postnatal rat brain. DPSCs were transplanted into the cerebrospinal fluid of 3-day-old male Wistar rats. Cortical lesion was induced by touching a cold (-60°C) metal stamp to the calvaria over the forelimb motor cortex. Four weeks later cell localization was detected by fluorescent microscopy and neuronal cell markers were studied by immunohistochemistry. To investigate electrophysiological properties of engrafted, fluorescently labeled DPSCs, 300µm-thick horizontal brain slices were prepared and the presence of voltage-dependent sodium and potassium channels were recorded by patch clamping. Predifferentiated donor DPSCs injected into the cerebrospinal fluid of newborn rats migrated as single cells into a variety of brain regions. Most of the cells were localized in the normal neural progenitor zones of the brain, the subventricular zone (SVZ), subgranular zone (SGZ) and subcallosal zone (SCZ). Immunohistochemical analysis revealed that transplanted DPSCs expressed the early neuronal marker N-tubulin, the neuronal specific intermediate filament protein NF-M, the postmitotic neuronal marker NeuN, and glial GFAP. Moreover, the cells displayed TTX sensitive voltage dependent (VD) sodium currents (I(Na)) and TEA sensitive delayed rectifier potassium currents (K(DR)). Four weeks after injury, fluorescently labeled cells were detected in the lesioned cortex. Neurospecific marker expression was increased in DPSCs found in the area of the cortical lesions compared to that in fluorescent cells of uninjured brain. TTX sensitive VD sodium currents and TEA sensitive K(DR) significantly increased in labeled cells of the cortically injured area. In conclusion, our data demonstrate that engrafted DPSC-derived cells integrate into the host brain and show neuronal properties not only by expressing neuron-specific markers but also by exhibiting voltage dependent sodium and potassium channels. This proof of concept study reveals that predifferentiated hDPSCs may serve as useful sources of neuro- and gliogenesis in vivo, especially when the brain is injured.

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01/24/2011 - Effect of platelet-rich plasma on dental stem cells derived from human impacted third molars.

Regen Med. 2011 Jan;6(1):67-79.

Lee UL, Jeon SH, Park JY, Choung PH.

Department of Oral & Maxillofacial Surgery, School of Dentistry, Seoul National University, Seoul, South Korea.

Abstract

AIM: Platelet-rich plasma (PRP) is fabricated from autologous blood and extensively used to promote soft and hard tissue healing. In the dental field, autologous PRP is widely used combined with dental implant installation and bone graft. This study will evaluate the biologic effect of PRP on the proliferation and the differentiation of human dental stem cells, and find the key cytokines inducing these effects to estimate the clinical feasibility of PRP for dental tissue engineering.

MATERIALS & METHODS: Venous blood was obtained from four individuals and each PRP was fabricated. The human dental stem cells were obtained from the periodontal ligament (PDL) and dental pulp of the surgically extracted human third molars and expanded in vitro. Immunocytochemical staining and flow cytometry with STRO-1 and CD146 confirmed existence of mesenchymal stem cells in the PDL and dental pulp. The effect of PRP on the proliferation of PDL stem cells (PDLSCs) and dental pulp stem cells (DPSCs) was assessed by colony-forming ability measurement, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and bromodeoxyuridine incorporation assay. Alkaline phosphatase activity and calcium deposit were measured to evaluate the mineralization effect of PRP PDLSCs and DPSCs. Alizarin red S staining was used to detect mineral nodules. Odontogenic and osteogenic gene expressions were evaluated in the PRP-treated PDLSCs and DPSCs by real-time quantitative PCR. A protein array was performed to detect the key cytokines that have an important role in the tissue regenerative effect of PRP.

RESULTS: Flow cytometry cell sorting showed that the cells from human PDL and dental pulp contained mesenchymal stem cell populations. Colony-forming ability and cellular proliferation of the dental stem cells were increased at 0.5 and 1% PRP concentration but decreased at 5% concentration. Long-term treatment with 1% PRP enhanced proliferation of the human dental stem cells PDLSCs and DPSCs by 120 h and showed the most significant enhancement at 96 h. PRP also promoted mineralization differentiation of the two kinds of dental stem cells as shown by measurement of alkaline phosphatase activity and calcium deposit under mineralization conditioned media. Increased formation of mineral nodules stained with alizarin red was observed in both PDLSCs and DPSCs after treatment with 1% PRP. Real-time quantitative PCR showed higher odontogenic and osteogenic gene expressions in PRP-treated PDLSCs and DPSCs. RANTES/CCL5 and ICAM-1 were the two key cytokines that were detected in human cytokine array with PRP.

CONCLUSION: The appropriate concentration of the PRP treatment enhanced proliferation and mineralization differentiation of human dental stem cells. RANTES/CCL5 and ICAM-1 might play an important role in PRP-induced tissue regeneration but further study is needed to investigate the whole mechanism.

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12/12/2010 - Researchers at Boston University use stem cells to repair teeth

Doctor George Huang discusses baby teeth and wisdom teeth as a potential source of stem cells that can be utilized in the treatment of disease and trauma.  

By Doctor Alan A. Winter, DDS

Boston University Professor Doctor George Huang, the Herbert Schilder Chair in Endodontics, Director at Boston University’s Henry M. Goldman School of Dental Medicine and Science Advisor to StemSave, discusses his research utilizing dental stem cells.
 
Dr. Huang and his team demonstrated the ability of dental stem cells to repair teeth; more specifically, by facilitating the growth of dentin and pulp in a tooth model using a compromised tooth, biological scaffolding and stem cells obtained from wisdom teeth.   The re-growth of pulp and dentin was done in vivo utilizing mice.  Dr. Huang and his team plan to apply the successful methods to larger animals and believes that stem cell based biologic oriented repair of dental trauma will begin to find its way into the dentist’s office in the near future.

Confirming dental stem cells ability to differentiate into various other types of tissue such as bone, neural cells and as a source for iPS cells, Dr. Huang envisages dental stem cells as a potential source of very ‘plastic’ stem cells that can be utilized to treat a wide variety of disease and trauma as regenerative medical treatments advance.

More at http://www.bu.edu/today/node/11853, with Video by Robin Berghaus, Story by Caleb Daniloff. Photos by Cydney Scott.

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12/02/2010 - Dental Stem Cells Differentiated into Dystrophin Producing Muscle Cells

Latest Study Advances Muscular Dystrophy Research and Treatment.

Dental Stem Cells, in the latest example of their plasticity, were differentiated into dystrophin producing multi-nucleated muscle cells.   The research, published recently in PLoS One was led by Dr. Jeremy Mao, Professor and Director of the Tissue Engineering and Regenerative Medicine Laboratory (TERML) of Columbia University Medical Center and Chief Scientific Advisor to StemSave.

Dr. Mao’s utilization of myogenic progenitor cells derived from dental stem cells demonstrated significantly higher numbers of dystrophin producing cells than the parent heterogeneous stem cells from which they were derived.  The latest research suggests therapeutic potential for muscle regeneration and has implications for disorders such as Muscular Dystrophy where the inability of the body to produce dystrophin results in health complications. 

The latest research, along with recently published research demonstrating the ability of dental stem cells to differentiate into bone, myocardiocytes (heart muscle) and insulin producing pancreatic beta cells, supports the wisdom of banking stem cells from teeth. 

The ability of dental stem cells to differentiate into various types of cells (often referred to as their ‘plasticity’) makes teeth a source of valuable stem cells to utilize in the treatment of a potentially wide range of trauma and disease.   These valuable stem cells can be recovered during routine dental procedures thus making it both convenient and affordable to bank your own stem cells for use in emerging regenerative therapies.

by Dr. Dean Vafiadis, DDS

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11/14/2010 - New Study: Wisdom Teeth Valuable Stem Cell Source

By Gregory Chotkowski, DMD

A new study released this week by a team of researchers at the National Institute of Advanced Industrial Science and Technology in Japan shows that third molars – commonly known as wisdom teeth – are a powerful source of valuable personal stem cells, which can be stored for future use.

Wisdom teeth are often removed in routine procedures and discarded; the scientists were able to generate active stem-cell lines from the pulp or the material found inside the teeth. The stem cells are similar to those found inside bone marrow, but far easier to collect.

The team switched on several key genes in the tooth-derived stem cells and successfully programmed them to grow into, or “differentiate”, into a wide variety of different tissue types in human body, including the heart. (See the video of these cells functioning as beating cardiomyocytes, below). The reprogrammed tooth-derived stem cells were also found to be as many as 100 times more efficient than skin-derived induced pluripotential cells or iPS cells.

 

 

As the research demonstrates, stem cells found in wisdom teeth are highly efficient and possess a significant degree of plasticity which suggest their applicability in a broad range of regenerative therapies to treat a wide variety of disease and trauma.    Individuals and families have the opportunity to bank these very versatile and very valuable stem cells found in their wisdom teeth conveniently and affordably.  These banked stem cells will be readily available to the individual/family when and if needed as emerging regenerative medicine therapies are developed.

One of the most promising aspects of this research area is having access to these very versatile stem cells found in wisdom teeth and the ability to preserve them in liquid nitrogen indefinitely. These banked stem cells will be readily available to an individual when and if needed as anticipated regenerative medicine breakthroughs occur.

SOURCES
http://www.physorg.com/news203339769.html
Induction of Pluripotent Stem Cells from Human Third Molar Mesenchymal Stromal Cells, July 1, 2010, doi: 10.1074/jbc.M109.055889 September 17, 2010 The Journal of Biological Chemistry, 285, 29270-29278

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11/13/2010 - Characterization of Dental Pulp Stem Cells from Impacted Third Molars Cultured in Low Serum-Containing Medium.

Cells Tissues Organs. 2010 Nov 11. 

Karbanová J, Soukup T, Suchánek J, Pytlík R, Corbeil D, Mokrý J.

Department of Histology and Embryology, Charles University in Prague, Faculty of Medicine, Prague, Czech Republic.

We isolated and expanded stem cells from dental pulp from extracted third molars using an innovative culture method consisting of low serum-containing medium supplemented with epidermal growth factor and platelet-derived growth factor BB. We evaluated the differentiation potential of these cells when they were growing either adherently or as micromass/spheroid cultures in various media. Undifferentiated and differentiated cells were analyzed by flow cytometry, immunocytochemistry and immunoblotting. The flow cytometry results showed that the dental pulp stem cells (DPSCs) were positive for mesenchymal stromal cell markers, but negative for hematopoietic markers. Immunocytochemical and/or immunoblotting analyses revealed the expression of numerous stem cell markers, including nanog, Sox2, nestin, Musashi-1 and nucleostemin, whereas they were negative for markers associated with differentiated neural, vascular and hepatic cells. Surprisingly, the cells were only slightly positive for a-smooth muscle actin, and a heterogeneous expression of CD146 was observed. When cultured in osteogenic media, they expressed osteonectin, osteopontin and procollagen I, and in micromass cultures, they produced collagen I. DPSCs cultured in TGF-ß1/3-supplemented media produced extracellular matrix typical of cartilaginous tissue. The addition of vascular endothelial growth factor to serum-free media resulted in the expression of endothelial markers. Interestingly, when cultured in neurogenic media, DPSCs exhibited de novo or upregulated markers of undifferentiated and differentiated neural cells. Collectively, our data show that DPSCs are self-renewing and able to express markers of bone, cartilage, vascular and neural tissues, suggesting their multipotential capacity. Their easy accessibility makes these cells a suitable source of somatic stem cells for tissue engineering.

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11/13/2010 - Promising cell-based therapy for bone regeneration using stem cells from deciduous teeth, dental pulp, and bone marrow.

Cell Transplant. 2010 Nov 5.

Yamada Y, Ito K, Nakamura S, Ueda M, Nagasaka T.

We attempted to regenerate bone in a significant osseous defect with various stem cells from deciduous teeth, extracted from puppies, and grafted them into a parent canine mandible as an allograft, parent dental pulp, and bone marrow by tissue engineering and regenerative medicine technology using platelet-rich plasma as an autologous scaffold and signal molecules. Initially, teeth were extracted from a child and parent hybrid canine mandible region and bone marrow (canine mesenchymal stem cells; cMSCs), and parent teeth (canine dental pulp stem cells; cDPSCs), and stem cells were extracted from deciduous teeth (puppy deciduous teeth stem cells; pDTSCs). After 4 weeks, bone defects were prepared on both sides of the mandible with a trephine bar. Graft materials were implanted into these defects: 1) control (defect only), 2) PRP, 3) cMSCs/PRP, 4) cDPSCs/PRP, and 5) pDTSCs/PRP to investigate the effect of stem cells. The newly formed bones were evaluated by histology and histomorphometric analysis in the defects at 2, 4, and 8 weeks. According to histological observations, the cMSCs/PRP, cDPSCs/PRP, and pDTSCs/PRP group had well-formed mature bone and neovascularization compared with the control (defect only) and PRP groups at 4 and 8 weeks, respectively, and the mineralized tissues in cMSCs/PRP, cDPSCs/PRP, and pDTSCs/PRP specimens were positive for osteocalcin at 8 weeks. Histometrically, newly formed bone areas were 19.0±2.9% (control), 19.7±6.0% (PRP), 52.8±3.5% (cMSCs/PRP), 61.6±1.3% (cDPSCs/PRP) and 54.7±2.2% (pDTSCs/PRP) at 8 weeks. There were significant differences between cMSCs, cDPSCs, pDTSCs/PRP, and control and PRP groups. These results demonstrate that stem cells from deciduous teeth, dental pulp, and bone marrow with PRP have the ability to form bone, and bone formation with DTSCs might have the potential to generate a graft between a child and parent. This pre-clinical study could pave the way for stem cell therapy in orthopedics and oral maxillofacial reconstruction for clinical application.

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11/13/2010 - Telomere attrition occurs during ex vivo expansion of human dental pulp stem cells.

J Biomed Biotechnol. 2010;2010:673513. Epub 2010 Oct 4.

Mokry J, Soukup T, Micuda S, Karbanova J, Visek B, Brcakova E, Suchanek J, Bouchal J, Vokurkova D, Ivancakova R.

Department of Histology and Embryology, Faculty of Medicine in Hradec Kralove, Charles University in Prague, Simkova 870, 50038 Hradec Kralove, Czech Republic. mokry@lfhk.cuni.cz

Abstract

We provide a detailed characteristic of stem cells isolated and expanded from the human dental pulp. Dental pulp stem cells express mesenchymal cell markers STRO-1, vimentin, CD29, CD44, CD73, CD90, CD166, and stem cell markers Sox2, nestin, and nucleostemin. They are multipotent as shown by their osteogenic and chondrogenic potential. We measured relative telomere length in 11 dental pulp stem cell lines at different passages by quantitative real-time PCR. Despite their large proliferative capacity, stable viability, phenotype, and genotype over prolonged cultivation, human dental pulp stem cells suffer from progressive telomere shortening over time they replicate in vitro. Relative telomere length (T/S) was inversely correlated with cumulative doubling time. Our findings indicate that excessive ex vivo expansion of adult stem cells should be reduced at minimum to avoid detrimental effects on telomere maintenance and measurement of telomere length should become a standard when certificating the status and replicative age of stem cells prior therapeutic applications.

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10/12/2010 - Ecto-mesenchymal stem cells from dental pulp are committed to differentiate into active melanocytes.

Eur Cell Mater. 2010 Oct 7;20:295-305.

Paino F, Ricci G, De Rosa A, D'Aquino R, Laino L, Pirozzi G, Tirino V, Papaccio G.

Department of Experimental Medicine, Histology and Embryology, Tissue Engineering and Regenerative Medicine (TERM) Division, School of Medicine, Second University of Naples, 5 via L. Armanni, I-80138 Napoli, Italy.gianpaolo.papaccio@unina2.it.

Dental pulp stem cells (DPSCs) are multipotent stem cells derived from neural crest and mesenchyme and have the capacity to differentiate into multiple cell lineages. It has already been demonstrated that DPSCs differentiate into melanocyte-like cells but only when cultivated in a specific melanocyte differentiating medium. In this study we have shown, for the first time, that DPSCs are capable of spontaneously differentiating into mature melanocytes, which display molecular and ultrastructural features of full development, including the expression of melanocyte specific markers and the presence of melanosomes up to the terminal stage of maturation. We have also compared the differentiating features of DPSCs grown in different culture conditions, following the timing of differentiation at molecular and cytochemical levels and found that in all culture conditions full development of these cells was obtained, although at different times. The spontaneous differentiating potential of these cells strongly suggests their possible applications in regenerative medicine.

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10/12/2010 - Induction of human dental pulp stem cells of premolars into osteoblast-like cells by mineralizing culture medium.

Shanghai Kou Qiang Yi Xue. 2010 Aug;19(4):398-402.

Zhang XY, Li XT, Zeng XL.

Department of Orthodontics, Peking University School and Hospital of Stomatology. Beijing 100081, China.

Abstract

PURPOSE: To induce human dental pulp stem cells(HDPSCs) of premolars into osteoblast-like cells by mineralizing culture medium.

METHODS: HDPSCs of premolars were induced by mineralizing culture medium for 28 days.The activity of ALP was examined by enzyme histochemical staining on the 7th and 28th day. The ability of mineralization of HDPSCs was detected by Alizarin-red staining on the 14th,21st and 28th day. The gene expression of ALP,DSPP,BSP,OCN on day 0,3,5,7,14,21 and 28 was evaluated by RT-PCR. The protein expression of BSP,OCN was analyzed by Western blotting and immunocytochemistry.

RESULTS: ALP was expressed and mineralized nodules were observed after induction of HDPSCs. ALP mRNA was detected since the 3rd day, while no expression of DSPP mRNA. The gene of BSP,OCN was expressed from the 5th day and exhibited increment with time. The expression trend of BSP protein was consistent with BSP mRNA. OCN stained positive since the 5th day.

CONCLUSIONS: HDPSCs of premolars could be induced to differentiate into osteoblast-like cells,which suggests that HDPSCs of premolars may be a potential source of cells used for bone-tissue engineering in the future. Supported by National Natural Science Foundation of China(Grant No.30772452).

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10/12/2010 - Human dental pulp stem cells protect mouse dopaminergic neurons against MPP(+) or rotenone.

Brain Res. 2010 Sep 17.

Nesti C, Pardini C, Barachini S, D'Alessandro D, Siciliano G, Murri L, Petrini M, Vaglini F.

RRMR/CUCCS (Rete Regionale di Medicina Rigenerativa/Center for the Clinical Use of Stem Cells), Italy; Stella Maris Scientific Institute, Pisa, Italy.

Abstract

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive death of substantia nigra dopaminergic neurons that results in a regional loss of striatal dopamine (DA) levels. Dental pulp contains ex vivo-expandable cells called dental pulp stem cells (DPSCs), with the capacity to differentiate into multiple cell lineages. More interestingly, due to their embryonic origin, DPSCs express neurotrophic factors such as brain-derived neurotrophic factor, nerve growth factor and glial cell-derived neurotrophic factor. Aim of the present study was to investigate the neuroprotective effects of DPSCs against MPP(+) (2.5, 5, and 10µM) and rotenone (0.25, 0.5 and 1µM) in an in vitro model of PD, using an indirect co-culture system with mesencephalic cell cultures. When mesencephalic cultures were challenged with MPP(+) or rotenone, in presence of DPSCs a statistically significant protective effect was observed at all the tested doses in terms of DA uptake. DPSCs protective effect on DA neurons was also confirmed by immunocytochemistry: an increased number of spared tyrosine hydroxylase (TH)(+) cells was observed in co-culture conditions compared to controls, and neurons showed longer processes in comparison with mesencephalic cells grown without DPSCs. In conclusion, the co-culture with DPSCs significantly attenuated MPP(+) or rotenone-induced toxicity in primary cultures of mesencephalic neurons. Considering that the direct contact between the two cell types was prevented, it can be speculated that neuroprotection could be due to soluble factors such as BDNF and NGF, released by DPSCs. Blocking BDNF and NGF with neutralizing antibodies, the neuroprotecting effect of DPSCs was completely abolished. Therefore DPSCs can be viewed as possible candidates for studies on cell-based therapy in neurodegenerative disorders.

PMID: 20854799 [PubMed - as supplied by publisher]

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10/12/2010 - Stem cells from human exfoliated deciduous teeth--isolation, long term cultivation and phenotypical analysis.

Acta Medica (Hradec Kralove). 2010;53(2):93-9.

Suchánek J, Visek B, Soukup T, El-Din Mohamed SK, Ivancaková R, Mokr? J, Aboul-Ezz EH, Omran A.

Charles University in Prague, Faculty of Medicine, Department of Dentistry and University Hospital Hradec Králové, Czech Republic. suchanekj@lfhk.cuni.cz

AIMS: Our aims were to isolate stem cells from human exfoliated deciduous teeth (SHED), to cultivate them in vitro and to investigate their basic biological properties, phenotype and to compare our findings with dental pulp stem cells (DPSC) isolated from permanent teeth.

METHODS: Dental pulp was gently evacuated from exfoliated teeth. After enzymatic dissociation of dental pulp, SHED were cultivated in modified cultivation media for mesenchymal adult progenitor cells containing 2% FCS and supplemented with growth factors and insulin, transferrin, sodium (ITS) supplement. Cell viability and other biological properties were examined using a Vi-Cell analyzer and a Z2-Counter. DNA analyses and phenotyping were performed with flow cytometry.

RESULTS: We were able to cultivate SHED over 45 population doublings. Our results showed that SHED cultivated under same conditions as DPSC had longer average population doubling time (41.3 hrs for SHED vs. 24.5 hrs for DPSC). Phenotypic comparison of cultivated SHED to that of cultivated DPSC showed differential expression CD29, CD44, CD71, CD117, CD 166. During long-term cultivation, SHED did not showed any signs of degeneration or spontaneous differentiation.

CONCLUSIONS: We isolated stem cells from exfoliated teeth. In comparison to DPSC, SHED proliferation rate was about 50% slower, and SHED showed slightly different phenotype. These cells may be extremely useful for stem cell tissue banking, further stem cell research and future therapeutic applications.

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08/22/2010 - Inherent Differential Propensity of Dental Pulp Stem Cells Derived from Human Deciduous and Permanent Teeth.

J Endod. 2010 Sep;36(9):1504-1515.

Govindasamy V, Abdullah AN, Sainik Ronald V, Musa S, Che Ab Aziz ZA, Zain RB, Totey S, Bhonde RR, Abu Kasim NH.

Stempeutics Research Malaysia Sdn Bhd, Kuala Lumpur, Malaysia

INTRODUCTION: Lately, several new stem cell sources and their effective isolation have been reported that claim to have potential for therapeutic applications. However, it is not yet clear which type of stem cell sources are most potent and best for targeted therapy. Lack of understanding of nature of these cells and their lineage-specific propensity might hinder their full potential. Therefore, understanding the gene expression profile that indicates their lineage-specific proclivity is fundamental to the development of successful cell-based therapies.

METHODS: We compared proliferation rate, gene expression profile, and lineage-specific propensity of stem cells derived from human deciduous (SCD) and permanent teeth (DPSCs) over 5 passages.

RESULTS: The proliferation rate of SCD was higher (cell number, 25 x 10(6) cells/mL; percent colony-forming units [CFUs], 151.67 +/- 10.5; percent cells in S/G2 phase, 12.4 +/- 1.48) than that of DPSCs (cell number, 21 x 10(6) cells/mL; percent CFUs, 133 +/- 17.62; percent cells in S/G2 phase, 10.4 +/- 1.18). It was observed that fold expression of several pluripotent markers such as OCT4, SOX2, NANOG, and REX1 were higher (>2) in SCD as compared with DPSCs. However, DPSCs showed higher expression of neuroectodermal markers PAX6, GBX2, and nestin (fold expression >100). Similarly, higher neurosphere formation and neuronal marker expression (NF, GFAP) were found in the differentiated DPSCs into neuron-like cells as compared with SCD.

CONCLUSIONS: This study thus demonstrates that both SCD and DPSCs exhibit specific gene expression profile, with clear-cut inclination of DPSCs toward neuronal lineage.

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08/22/2010 - Micromanipulation of culture niche permits long-term expansion of dental pulp stem cells-an economic and commercial angle.

In Vitro Cell Dev Biol Anim. 2010 Aug 20.

Govindasamy V, Ronald VS, Totey S, Binti Din S, Mustafa WM, Totey S, Zakaria Z, Bhonde RR.

Stempeutics Research Malaysia, Sdn Bhd (773817-K) Lot 3-i-7, Enterprise 4, Technology Park Malaysia, Bukit Jalil, 57000, Kuala Lumpur, Malaysia

Stem cells isolated from dental pulp possess the capacity for self-renewal and the potential for multi-lineage differentiation. However, dental pulp stem cells have different characteristics in terms of their culture conditions. The success of stem cells culture is governed by its micro-environmental niche. Therefore, we studied the effects of culture niche on long-term expansion of dental pulp stem cells in terms of cell morphology, growth kinetics, senescence pattern, cell surface marker expression differentiation capacity, and seeding plating density of dental pulp stem cells in four different, widely used media composition Among the various basal media tested, alpha-minimum essential media and knock out-minimum essential media supplemented with 10% fetal bovine serum were found to be the most optimal media composition in preserving the phenotypic characteristics and differentiation potential for prolonged periods as compared with DMEM-F12 and DMEM-LG. Plating density has been shown to affect overall yield. As a conclusion, the adoption of an appropriate culture system significantly improved cell yield, thus enabling the attainment of sufficient yields for therapeutic applications economizing in terms of cost of production and minimizing seeding cell density for maximum yield.

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08/22/2010 - Stem Cells from Human-Exfoliated Deciduous Teeth Can Differentiate into Dopaminergic Neuron-Like Cells.

Stem Cells Dev. 2010 Feb 4.

Wang J, Wang X, Sun Z, Wang X, Yang H, Shi S, Wang S.

1 Salivary Gland Disease Center and the Molecular Laboratory for Gene Therapy and Tooth Regeneration, Capital Medical University School of Stomatology , Beijing, People's Republic of China .

Stem cells from human exfoliated deciduous teeth (SHED) have been identified as a novel population of postnatal stem cells capable of differentiating into neural cells, odontogenic cells, and adipocytes. SHED were reported to differentiate into neural cells based on cellular morphology and the expression of early neuronal markers when cultured under neural inductive conditions. This study therefore investigated the therapeutic efficacy of SHED in alleviating Parkinson's disease (PD) in a rat model. We found that SHED could be induced to form neural-like spheres in a medium optimized for neural stem cells in vitro. After incubation with a cocktail of cytokines including sonic hedgehog, fibroblast growth factor 8, glial cell line-derived neurotrophic factor, and forskolin, these SHED-derived spheres further differentiated into a cell population that contained specific dopaminergic neurons. Moreover, transplantation of SHED spheres into the striatum of parkinsonian rats partially improved the apomorphine-evoked rotation of behavorial disorders compared to transplantation of control SHED. Our data indicate that SHED, potentially derived from neural crest cells, may be an optimal source of postnatal stem cells for PD treatment.

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07/20/2010 - Development of a serum-free system to expand dental-derived stem cells: PDLSCs and SHEDs.

J Cell Physiol. 2010 Jul 12.

S A T, S S, D K.

Department of Periodontics and Oral Medicine, University of Michigan; Ann Arbor, MI USA;

Recently, extracted teeth have been identified as a viable source of stem cells for tissue regenerative approaches. Current expansion of these cells requires incorporation of animal sera; yet, a fundamental issue underlying cell cultivation methods for cell therapy regards concerns in using animal sera. In this study, we investigated the development of a chemically-defined, serum-free media (K-M) for the expansion of human periodontal ligament stem cells (PDLSCs) and human stem cells from exfoliated deciduous teeth (SHEDs). Proliferation assays were performed comparing cells in serum-containing media (FBS-M) with cells cultured in four different serum-free medium and these demonstrated that in these medium, the cell proliferation of both cell types was significantly less than the proliferation of cells in FBS-M. Additional proliferation assays were performed using pre-coated fibronectin (FN) tissue culture plates and of the four serum-free medium, only K-M enabled PDLSCs and SHEDs to proliferate at higher rates than cells cultured in FBS-M. Next, alkaline phosphatase activity showed that PDLSCs and SHEDs exhibited similar osteogenic potential whether cultured in K-M or FBS-M, and, additionally, cells retained their multipotency in K-M as seen by expression of chondrogenic and adipogenic genes, and positive Von Kossa, Alcian blue, and Oil Red O staining. Finally, differential expression of 84 stem cell associated genes revealed that for most genes, PDLSCs and SHEDs did not differ in their expression regardless of whether cultured in K-M or FBS-M. Taken together, the data suggest that K-M can support the expansion of PDLSCs and SHEDs and maintainence of their multipotency. J. Cell. Physiol. (c) 2010 Wiley-Liss, Inc.

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07/19/2010 - Expression of multiple stem cell markers in dental pulp cells cultured in serum-free media.

J Endod. 2010 Jul;36(7):1139-44. Epub 2010 Apr 10.

Hirata TM, Ishkitiev N, Yaegaki K, Calenic B, Ishikawa H, Nakahara T, Mitev V, Tanaka T, Haapasalo M.

Department of Oral Health, Nippon Dental University, School of Life Dentistry at Tokyo, Tokyo, Japan.

INTRODUCTION: Stem cell lines are usually grown in medium containing animal products. Fetal bovine serum (FBS) is an important additive for cell growth; however, the allergenic potential and the possibility of contamination when we use a medium containing serum would be a barrier to transplantation and consequently to the introduction of cell therapy methods into clinical applications. METHODS: Dental mesenchymal cells were isolated and expanded in vitro and maintained in 4 different serum-free media (SFMs): SFM#1 (ITS-X, embryotrophic factor [ETF]); SFM#2 (ITS-X); SFM#3 (ETF); and SFM#4 (ETF, sodium pyruvate, ascorbic acid, fibroblast growth factor [FGF-a], acidic). Viability, proliferative, and immunocytochemical tests for the cells were performed by using 4 stem cell markers (CD44H, CK19, nestin, and P63) for ectoderm, mesoderm, and endoderm. RESULTS: Viability tests showed a significant difference between the control and SFMs in both deciduous tooth pulp cells (DTPCs) and wisdom tooth pulp cells (WTPCs). However, all SFMs demonstrated 84%-90% viability, whereas the control showed 90%-93%. In both DTPCs and WTPCs, SFM#1 had the highest proliferation rate among the 4 SFMs. Immunocytochemistry stained positive stem cell markers most intensely in cells cultured with SFM#1. Furthermore, all stem cell markers for ectoderm, mesoderm, and endoderm were expressed in the cells cultured with SFM#1. CONCLUSIONS: SFM#1 showed an acceptable survival rate, the highest proliferation rate, and the strongest expression of all the stem cell markers. SFM#1 proved to be a suitable medium for the culture of human dental pulp stem cells and to preserve pluripotency in differentiation. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

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07/19/2010 - Hypoxia enhances colony formation and proliferation but inhibits differentiation of human dental pulp cells.

Arch Oral Biol. 2010 Jul 12.

Iida K, Takeda-Kawaguchi T, Tezuka Y, Kunisada T, Shibata T, Tezuka KI.

Department of Oral and Maxillofacial Science, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu City, Gifu 501-1194, Japan.

The hypoxia condition was expected to be suitable for the establishment and maintenance of human dental pulp cells (hDPCs), because they reside in a low-oxygen environment in vivo. Therefore, we presently examined the effects of hypoxia on the proliferation and differentiation of hDPCs in vitro. hDPCs grown under 3% O(2) showed a significantly higher proliferation rate than those under 21% O(2). Then, we prepared hypoxic cultures of hDPCs from older patients' teeth having inflammation and succeeded in recovering and expanding a small number of hDPCs. These cells were confirmed to have capability for osteo/odontogenic differentiation. Hypoxia suppressed the osteo/odontogenic differentiation of hDPCs in vitro and increased the number of cells expressing STRO-1, an early mesenchymal stem cell marker. This simple method will increase the possibility to obtain living hDPCs from damaged and/or aged tissues, from which it is ordinarily difficult to isolate living stem cells with differentiation capability. Copyright © 2010. Published by Elsevier Ltd.

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06/19/2010 - Immunomodulatory properties of stem cells from human exfoliated deciduous teeth.

Stem Cell Res Ther. 2010 Mar 15;1(1):5.

Yamaza T, Kentaro A, Chen C, Liu Y, Shi Y, Gronthos S, Wang S, Shi S.

Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, 2250 Alcazar Street, CSA 103, Los Angeles, CA 90033, USA. yamazata@dent.kyushu-u.ac.jp.

Abstract

ABSTRACT : INTRODUCTION : Stem cells from human exfoliated deciduous teeth (SHED) have been identified as a population of postnatal stem cells capable of differentiating into osteogenic and odontogenic cells, adipogenic cells, and neural cells. Herein we have characterized mesenchymal stem cell properties of SHED in comparison to human bone marrow mesenchymal stem cells (BMMSCs). METHODS : We used in vitro stem cell analysis approaches, including flow cytometry, inductive differentiation, telomerase activity, and Western blot analysis to assess multipotent differentiation of SHED and in vivo implantation to assess tissue regeneration of SHED. In addition, we utilized systemic SHED transplantation to treat systemic lupus erythematosus (SLE)-like MRL/lpr mice. RESULTS : We found that SHED are capable of differentiating into osteogenic and adipogenic cells, expressing mesenchymal surface molecules (STRO-1, CD146, SSEA4, CD73, CD105, and CD166), and activating multiple signaling pathways, including TGFbeta, ERK, Akt, Wnt, and PDGF. Recently, BMMSCs were shown to possess an immunomodulatory function that leads to successful therapies for immune diseases. We examined the immunomodulatory properties of SHED in comparison to BMMSCs and found that SHED had significant effects on inhibiting T helper 17 (Th17) cells in vitro. Moreover, we found that SHED transplantation is capable of effectively reversing SLE-associated disorders in MRL/lpr mice. At the cellular level, SHED transplantation elevated the ratio of regulatory T cells (Tregs) via Th17 cells. CONCLUSIONS : These data suggest that SHED are an accessible and feasible mesenchymal stem cell source for treating immune disorders like SLE.

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06/18/2010 - Osteogenic properties of human dental pulp stem cells.

J Biol Regul Homeost Agents. 2010 Apr-Jun;24(2):167-75.

Mori G, Centonze M, Brunetti G, Ballini A, Oranger A, Mori C, Lo Muzio L, Tetè S, Ciccolella F, Colucci S, Grano M, Grassi FR.

Department of Biomedical Science, University of Foggia Medical School, Foggia, Italy. g.mori@unifg.it

Abstract

Stem cells are a promising tool for bone tissue regeneration. Dental pulp stem cells (DPSCs) can be easily obtained even in human young adults. In this study we investigated the capability of DPSCs, to express the osteoblastic phenotype when cultured with osteogenic medium. DPSCs isolated from the dental pulp of impacted third molar teeth were cultured with appropriate medium to induce osteoblast differentiation. Using Western-Blot, RT-PCR and microarray analysis, we studied the expression of osteoblastic parameter, and by Von Kossa staining we evaluated the production of mineralized matrix nodules. The results were compared with controls represented by undifferentiated DPSCs. DPSCs, differentiated into osteoblast-like cells, express large amount of alkaline phosphatase (ALP), collagen I (Coll I), osteopontin (OPN) and osteocalcin (OCN), all these parameters characterizing the osteoblastic phenotype. Differentiated DPSCs express Runx2 and JunB, a member of the AP-1 complex; both the transcription factors are associated with osteoblast differentiation and skeletal morphogenesis. Moreover, DPSCs express insulin growth factor-binding protein 5 (IGFBP-5), one of the regulating proteins of IGFs function. Finally, DPSCs can form mineralized matrix nodules that are a feature exclusive to osteoblasts. DPSCs could represent a potential source of osteoblasts to be used for bone regeneration.

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06/18/2010 - Stem/progenitor cells from inflamed human dental pulp retain tissue regeneration potential.

Regen Med. 2010 May 14.

Alongi DJ, Yamaza T, Song Y, Fouad AF, Romberg EE, Shi S, Tuan RS, Huang GT.

University of Maryland, College of Dental Surgery, MD, USA; and Boston University School of Dental Medicine, Department of Endodontics, Boston, MA 02118, USA.

Abstract

Background: Potent stem/progenitor cells have been isolated from normal human dental pulps termed dental pulp stem cells (DPSCs). However, it is unknown whether these cells exist in inflamed pulps (IPs). Aims: To determine whether DPSCs can be identified and isolated from IPs; and if they can be successfully cultured, whether they retain tissue regeneration potential in vivo. Materials & methods: DPSCs from freshly collected normal pulps (NPs) and IPs were characterized in vitro and their tissue regeneration potential tested using an in vivo study model. Results: The immunohistochemical analysis showed that IPs expressed higher levels of mesenchymal stem cell markers STRO-1, CD90, CD105 and CD146 compared with NPs (p < 0.05). Flow cytometry analysis showed that DPSCs from both NPs and IPs expressed moderate to high levels of CD146, stage-specific embryonic antigen-4, CD73 and CD166. Total population doubling of DPSCs-IPs (44.6 +/- 2.9) was lower than that of DPSCs-NPs (58.9 +/- 2.5) (p < 0.05), and DPSCs-IPs appeared to have a decreased osteo/dentinogenic potential compared with DPSCs-NPs based on the mineral deposition in cultures. Nonetheless, DPSCs-IPs formed pulp/dentin complexes similar to DPSCs-NPs when transplanted into immunocompromised mice. Conclusion: DPSCs-IPs can be isolated and their mesenchymal stem cell marker profiles are similar to those from NPs. Although some stem cell properties of DPSCs-IPs were altered, cells from some samples remained potent in tissue regeneration in vivo.

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04/18/2010 - Osteogenic differentiation of stem cells derived from human periodontal ligaments and pulp of human exfoliated deciduous teeth.

Cell Tissue Res. 2010 Mar 23.

Chadipiralla K, Yochim JM, Bahuleyan B, Huang CY, Garcia-Godoy F, Murray PE, Stelnicki EJ.

Craniofacial Research Laboratory, College of Dental Medicine, Nova Southeastern University, Fort Lauderdale, Fla., USA.

Multipotent stem cells derived from periodontal ligaments (PDLSC) and pulp of human exfoliated deciduous teeth (SHED) represent promising cell sources for bone regeneration. Recent studies have demonstrated that retinoic acid (RA) and dexamethasone (Dex) induce osteogenesis of postnatal stem cells. The objective of this study was to examine the effects of RA and Dex on the proliferation and osteogenic differentiation of SHED and PDLSC and to compare the osteogenic characteristics of SHED and PDLSC under RA treatment. SHED and PDLSC were treated with serum-free medium either alone or supplemented with RA or Dex for 21 days. The proliferation of SHED and PDLSC was significantly inhibited by both RA and Dex. RA significantly upregulated gene expression and the activity of alkaline phosphatase in SHED and PDLSC. Positive Alizarin red and von Kossa staining of calcium deposition was seen on the RA-treated SHED and PDLSC after 21 days of culture. The influences of RA on the osteogenic differentiation of SHED and PDLSC were significantly stronger than with Dex. Supplemention with insulin enhanced RA-induced osteogenic differentiation of SHED. Thus, RA is an effective inducer of osteogenic differentiation of SHED and PDLSC, whereas RA treatment in combination with insulin supplementation might be a better option for inducing osteogenic differentiation. Significantly higher cell proliferation of PDLSC results in greater calcium deposition after 3-week culture, suggesting that PDLSC is a better osteogenic stem cell source. This study provides valuable information for efficiently producing osteogenically differentiated SHED or PDLSC for in vivo bone regeneration.

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11/21/2009 - Plasticity of stem cells derived from adult periodontal ligament.
Regen Med. 2009 Nov;4(6):809-21.

Huang CY, Pelaez D, Bendala JD, Garcia-Godoy F, Cheung HS.

Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA.

BACKGROUND: The neural crest contains pluripotent cells that can give rise to neurons and glial cells of the peripheral nervous system, endocrine cells, connective tissue cells, muscle cells and pigment cells during embryonic development. Stem cells derived from the neural crest may still reside in neural crest derivatives including the periodontal ligament (PDL). However, the pluripotency of PDL-derived stem cells has not been investigated. AIM: To identify subpopulations of stem cells from the adult PDL and study their pluripotency. Human PDLs were harvested from impacted wisdom teeth (patients aged 19-22 years). RESULTS: This study demonstrated that subpopulations of PDL cells expressed embryonic stem cell markers (Oct4, Sox2, Nanog and Klf4) and a subset of neural crest markers (Nestin, Slug, p75 and Sox10). Such PDL cell subpopulations exhibited the potential to differentiate into neurogenic, cardiomyogenic, chondrogenic and osteogenic lineages. Furthermore, preliminary evidence suggesting insulin production of PDL cells might be indicative of the generation of cells of the endodermal lineage. CONCLUSION: These findings suggest that the PDL may contain pluripotent stem cells that originate from the neural crest. Our observations open the door to prospective autologous therapeutic applications for a variety of conditions.

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11/20/2009 - Potential role of dental stem cells in the cellular therapy of cerebral ischemia
Curr Pharm Des. 2009;15(33):3908-16

Yalvac ME, Rizvanov AA, Kilic E, Sahin F, Mukhamedyarov MA, Islamov RR, Palotás A.

Department of Genetics and BioEngineering, College of Engineering and Architecture, Yeditepe University, Istanbul, Turkey.

Stem cell based therapies for cerebral ischemia (CI) utilize different cell sources including embryonic stem cells (ESCs), neural stem cells (NSCs), umbilical cord blood cells (UCBCs), mesenchymal stem cells (MSCs), and some immortalized cell lines. To date, experimental studies showed that all of these cell sources have been successful to some extent in attenuating the ischemic damage and improving functional recovery after brain injury. Bone marrow derived MSCs seem to be the most widely used and well characterized cell source, which can be also employed for autologous transplantation. Currently, there are two main theories behind the therapeutic effect of stem cell transplantation for treating CIs. The first concept is cell replacement theory in which transplanted stem cells differentiate into progenitor and specialized somatic cells to supersede dying cells. The other hypothesis is based on immuno-modulatory, neuro-protective and neuro-trophic abilities of stem cells which help reducing stroke size and increasing the recovery of behavioral functions. Recent studies focusing on alternative stem cell sources have revealed that dental stem cells (DSCs), including dental pulp stem cells (DPSCs) and dental follicle cells (DFCs) possess properties of MSCs and NSCs. They differentiate into neural linage cells and some other cell types such as osteocytes, adipocytes, chondrocytes, muscle cells and hepatocytes. This review is intended to examine stem cell therapy approaches for CI and emphasize potential use of DSCs as an alternative cell source for the treatment of brain ischemia.

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11/18/2009 - Wisdom teeth: Mankind's future third vice-teeth?
Med Hypotheses. 2009 Sep 16.

Zou D, Zhao J, Ding W, Xia L, Jang X, Huang Y.

School of Stomatology, Tongji University, Shanghai 200072, China; Department of Stomatology, Shanghai East Hospital Affiliated to Tongji University, No.150 JiMO Road, Shanghai City 200011, China.

The third molar teeth (wisdom teeth) represent the last eruption of the teeth in the human dentition. Throughout evolution, the mandible has had a tendency to decrease in size; the third molar teeth are often impacted, resulting in incomplete tooth eruption that often causes clinical pericoronitis, dental caries, and pericemental abscess. Therefore, the wisdom teeth are often extracted. Moreover, wisdom teeth are often removed for clinical orthodontic treatment. On the other hand, tooth loss due to periodontal disease, dental caries, trauma, or a variety of genetic disorders continues to affect people's lives. Autologous tissues for dental tissue regeneration that could replace lost teeth could provide a vital alternative to currently available clinical treatments. To pursue this goal, we hypothesize that human third molar tooth buds can be obtained during development. Human wisdom tooth germination tissue could then be placed into an embryonic stem cell bank for storage. When the donor's other teeth are missing, embryonic stem cell and tissue engineering technologies, will permit the restoration of the missing teeth. Therefore wisdom teeth will be mankind's future third vice-teeth.

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11/10/2009 - Stem cell proliferation pathways comparison between human exfoliated deciduous teeth and dental pulp stem cells by gene expression profile from promising dental pulp.

J Endod. 2009 Nov;35(11):1536-42. Epub 2009 Sep 20.

Nakamura S, Yamada Y, Katagiri W, Sugito T, Ito K, Ueda M.

Department of Oral and Maxillofacial Surgery, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.

INTRODUCTION: Mesenchymal stem cells (MSCs) have been used for clinical application in tissue engineering and regenerative medicine (TERM). To date, the most common source of MSCs has been bone marrow. However, the bone marrow aspirate is an invasive and painful procedure for the donor. Thus, the identification and characterization of alternative sources of MSCs are of great importance. This study focused on the characterization of stem cells from human exfoliated deciduous teeth (SHED) compared with dental pulp stem cells (DPSCs) and bone marrow-derived mesenchymal stem cells (BMMSCs). METHODS: We have compared "stemness" such as the proliferation rate and the expression of stem cell marker of DPSCs, SHED, and BMMSCs. In addition, gene expression profile of DPSCs and SHED were analyzed by using DNA microarray. RESULTS: All cells isolated from the three sources exhibited MSC characteristics including a fibroblastic morphology, and the expression of mesenchymal stem-cell markers. The proliferation rate of SHED was significantly higher than that of DPSCs and BMMSCs (P < 0.05). The comparison of the gene expression profiles indicated 4386 genes with a changed expression between DPSCs and SHED by 2.0-fold or more. Higher expression in SHED was observed for genes that participate in pathways related to cell proliferation and extracellular matrix, including several cytokines such as fibroblast growth factor and tumor growth factor beta. CONCLUSIONS: Because of its advantages of a higher proliferation capability, abundant cell supply, and painless stem cell collection with minimal invasion, SHED could be a desirable option as a cell source for potential therapeutic applications.

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11/07/2009 - Isolating, culturing and characterizing stem cells of human dental pulp origin
Fogorv Sz. 2009 Oct;102(5):175-81

Kádár K, Porcsalmy B, Király M, Molnár B, Jobbágy-Ovári G, Somogyi E, Hermann P, Gera I, Varga G.

Semmelweis Egyetem Orálbiológiai Tanszék, Budapest.

Evidence has been accumulating for the presence of stem cells in dental tissues. The authors' studies aimed to produce primary culture from human dental pulp. Furthermore, they wanted to identify clonogenic cells with progenitor properties in these cultures, and to characterize their proliferative capacity. The dental pulp was isolated from surgically removed wisdom teeth. The extracellular matrix was enzymatically degraded to obtain isolated cells for culturing. Identification of STRO-1 mesenchymal stem cell marker was achieved by immunocytochemistry. Osteogenic differentiation was detected by the application of Alizarin Red. The proliferative activity of the cell cultures in response to serum, EGF and BMP2 was estimated by MTT assay. The authors' most important finding is the successful establishment of stable primary cell culture from human dental pulp tissue. The cultures can be passaged multiple times and they contain clonogenic, STRO-1 immunopositive cells. Their mineralization capacity was shown by mineralized deposits as a result of induction by suitable medium. The presence of serum increased, while both EGF and BMP2 concentration-dependently decreased the cell proliferation in the cultures. The authors' model provides the foundation for studies of the proliferation and differentiation of dental pulp cells at molecular level, and opens a new direction towards the biological regeneration of dental tissues.

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11/02/2009 - Human dental pulp stem cells with highly angiogenic and neurogenic potential for possible use in pulp regeneration.
Cytokine Growth Factor Rev. 2009 Nov 5.

Nakashima M, Iohara K, Sugiyama M.

Department of Oral Disease Research, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8522, Japan.

Dental caries is a common public health problem, causing early loss of dental pulp and resultant tooth loss. Dental pulp has important functions to sustain teeth providing nutrient and oxygen supply, innervation, reactionary/reparative dentin formation and immune response. Regeneration of pulp is an unmet need in endodontic therapy, and angiogenesis/vasculogenesis and neurogenesis are critical for pulp regeneration. Permanent and deciduous pulp tissue is easily available from teeth after extraction without ethical issues and has potential for clinical use. In this review, we introduce some stem cell subfractions, CD31(-)/CD146(-) SP cells and CD105(+) cells with high angiogenic and neurogenic potential, derived from human adult dental pulp tissue. Potential utility of these cells is addressed as a source of cells for treatment of cerebral and limb ischemia and pulp inflammation complete with angiogenesis and vasculogenesis.

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10/19/2009 - iPS cells reprogrammed from mesenchymal-like stem/progenitor cells of dental tissue origin.

Columbia University, Dentistry, New York, New York, United States; xy2137@columbia.edu.

Generation of induced pluripotent stem (iPS) cells holds a great promise for regenerative medicine and other aspects of clinical applications. Many types of cells have been successfully reprogrammed into iPS cells in the mouse system, however, reprogramming human cells have been more difficult. To date, human dermal fibroblasts are the most accessible and feasible cell source for iPS generation. Dental tissues derived from ectomesenchyme harbor mesenchymal-like stem/progenitor cells and some of the tissues have been treated as biomedical wastes, e.g., exfoliated primary teeth and extracted third molars. We asked whether stem/progenitor cells from discarded dental tissues can be reprogrammed into iPS cells. The four factors Lin28/Nanog/Oct4/Sox2 or c-Myc/Klf4/Oct4/Sox2 carried by viral vectors were used to reprogram three different dental stem/progenitor cells: stem cells from exfoliated deciduous teeth (SHED), stem cells from apical papilla (SCAP) and dental pulp stem cells (DPSCs). We showed that all three can be reprogrammed into iPS cells and appeared to be at a higher rate than fibroblasts. They exhibited a morphology indistinguishable from human embryonic stem (hES) cells in cultures and expressed hES cell markers SSEA-4, TRA-1-60, TRA-1-80, TRA-2-49, Nanog, Oct4 and Sox2. They formed embryoid bodies in vitro and teratomas in vivo containing tissues of all three germ layers. We conclude that cells of ectomesenchymal origin serve as an excellent alternative source for generating iPS cells.

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10/16/2009 - Dental tissue--new source for stem cells.
ScientificWorldJournal. 2009 Oct 14;9:1167-77.

Petrovic V, Stefanovic V.

University of Nis School of Medicine, Nis, Serbia. vlada@medfak.ni.ac.rs

Stem cells have been isolated from many tissues and organs, including dental tissue. Five types of dental stem cells have been established: dental pulp stem cells, stem cells from exfoliated deciduous teeth, stem cells from apical papilla, periodontal ligament stem cells, and dental follicle progenitor cells. The main characteristics of dental stem cells are their potential for multilineage differentiation and self-renewal capacity. Dental stem cells can differentiate into odontoblasts, adipocytes, neuronal-like cells, glial cells, osteoblasts, chondrocytes, melanocytes, myotubes, and endothelial cells. Possible application of these cells in various fields of medicine makes them good candidates for future research as a new, powerful tool for therapy. Although the possible use of these cells in therapeutic purposes and tooth tissue engineering is still in the beginning stages, the results are promising. The efforts made in the research of dental stem cells have clarified many mechanisms underlying the biological processes in which these cells are involved. This review will focus on the new findings in the field of dental stem cell research and on their potential use in the therapy of various disorders.

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10/09/2009 - Isolation and in vitro characterisation of dental pulp stem cells from natal teeth.
Histochem Cell Biol. 2009 Oct 9.

Karaöz E, Dogan BN, Aksoy A, Gacar G, Akyüz S, Ayhan S, Genç ZS, Yürüker S, Duruksu G, Demircan PC, Sariboyaci AE.

Stem Cell and Gene Therapy Research and Applied Center, Kocaeli University, 41380, Kocaeli, Turkey, ekaraoz@hotmail.com.

Dental pulp stem cells were primarily derived from the pulp tissues of exfoliated deciduous teeth, primary incisors and permanent third molar teeth. The aim of this study was to isolate and extensively characterise SCs derived from human natal dental pulp (hNDP). For characterisation, proliferation capacity, phenotypic properties, ultrastructural and differentiation characteristics and gene expression profiles were utilised. A comparison was done between the properties of NDP-SCs and the properties of mesenchymal stem cells (MSCs) from bone marrow (BM) of the human. Stem cells isolated from hNDP and hBM were analysed by flow cytometry, reverse transcriptase-PCR, Real Time-PCR, and immunocytochemistry. Both cell lines were directionally differentiated towards adipogenic, osteogenic chondrogenic, myogenic and neurogenic lineages. hNDP-SCs and hBM-MSCs expressed CD13, CD44, CD90, CD146 and CD166, but not CD3, CD8, CD11b, CD14, CD15, CD19, CD33, CD34, CD45, CD117, and HLA-DR. Ultrastructural characteristics of hNDP-SCs showed more developed and metabolically active cells. hNDP-SCs and hBM-MSCs expressed some adipogenic (leptin, adipophilin and PPARgamma), myogenic (desmin, myogenin, myosinIIa, and alpha-SMA), neurogenic (gamma-enolase, MAP2a,b, c-fos, nestin, NF-H, NF-L, GFAP and betaIII tubulin), osteogenic (osteonectin, osteocalcin, osteopontin, Runx-2, and type I collagen) and chondrogenic (type II collagen, SOX9) markers without any stimulation towards differentiation under basal conditions. Embryonic stem cell markers Oct4, Rex-1, FoxD-3, Sox2, and Nanog were also identified. The differentiation potential of hNDP-SCs and hBM-MSCs to adipogenic, osteogenic, chondrogenic, myogenic and neurogenic was shown. This report described the first successful isolation and characterisation of hNDP-SCs.

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10/02/2009 - Isolation and characterization of dental pulp stem cells from a supernumerary tooth.
J Oral Pathol Med. 2008 Oct;37(9):571-4. Epub 2008 Mar 6.

Huang AH, Chen YK, Lin LM, Shieh TY, Chan AW.

Grace Dental Clinic, School of Dentistry, Kaosiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan. andersonh@seed.net.tw

BACKGROUND: Dental pulp stem cells (DPSCs) were primarily derived from the pulp tissues of primary incisors and permanent third molar teeth, whereas no report to our knowledge has yet been documented on deriving DPSCs from the other tooth types. The aim of this study is to present a novel approach of harvesting stem cells from a supernumerary tooth (a mesiodens). MATERIALS AND METHODS: The pulp tissues from a mesiodens of a 20-year-old healthy male patient and the left lower deciduous canine of a healthy 10-year-old boy (the positive control) were extracted and cultured for DPSCs, which were examined with stem cells (Oct-4, Nanog and Rex-1) and differentiation (Osteonectin and Nestin) markers. Furthermore, DPSCs were directionally differentiated to osteogenic and adipogenic cell lineages. RESULTS: Dental pulp stem cells derived from the mesiodens were capable of differentiating into adipogenic and osteogenic lineages. The mesioden's DPSCs also expressed stem cell and differentiation markers, which suggested their stem cell origin and differentiation capability. All the aforementioned results for the mesiodens were consistent with those of the DPSCs derived from the positive control. CONCLUSION: We have demonstrated the feasibility of deriving DPSCs from a usually discarded tissue such as a supernumerary tooth.

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09/25/2009 - Implanted adult human dental pulp stem cells induce endogenous axon guidance
Stem Cells. 2009 Sep;27(9):2229-37

Arthur A, Shi S, Zannettino AC, Fujii N, Gronthos S, Koblar SA.

Mesenchymal Stem Cell Group, CSCR University of Adelaide, Adelaide, South Australia, Australia.

The human central nervous system has limited capacity for regeneration. Stem cell-based therapies may overcome this through cellular mechanisms of neural replacement and/or through molecular mechanisms, whereby secreted factors induce change in the host tissue. To investigate these mechanisms, we used a readily accessible human cell population, dental pulp progenitor/stem cells (DPSCs) that can differentiate into functionally active neurons given the appropriate environmental cues. We hypothesized that implanted DPSCs secrete factors that coordinate axon guidance within a receptive host nervous system. An avian embryonic model system was adapted to investigate axon guidance in vivo after transplantation of adult human DPSCs. Chemoattraction of avian trigeminal ganglion axons toward implanted DPSCs was mediated via the chemokine, CXCL12, also known as stromal cell-derived factor-1, and its receptor, CXCR4. These findings provide the first direct evidence that DPSCs may induce neuroplasticity within a receptive host nervous system. STEM CELLS 2009;27:2229-2237.

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09/13/2009 - Banking stem cells from human exfoliated deciduous teeth (SHED) saving for the future
J Clin Pediatr Dent. 2009 Summer;33(4):289-94.

Arora V, Arora P, Munshi AK.

Department of Conservative Dentistry and Endodontics, K.D. Dental College and Hospital, Mathura, India. vipin_endodontist@yahoo.co.in

Tooth derived cells are readily accessible and provide an easy and minimally invasive way to obtain and store stem cells for future use. Banking ones own tooth-derived stem cells is a reasonable and simple alternative to harvesting stem cells from other tissues. Obtaining stem cells from human exfoliated deciduous teeth (SHED) is simple and convenient, with little or no trauma. Every child loses primary teeth, which creates the perfect opportunity to recover and store this convenient source of stem cells--should they be needed to treat future injuries or ailments and presents a far better alternative to simply discarding the teeth or storing them as mementos from the past. Furthermore, using ones own stem cells poses few, if any, risks for developing immune reactions or rejection following transplantation and also eliminates the potential of contracting disease from donor cells. Stem cells can also be recovered from developing wisdom teeth and permanent teeth. Individuals have different opportunities at different stages of their life to bank these valuable cells. It is best to recover stem cells when a child is young and healthy and the cells are strong and proliferative. The purpose of this review is to discuss the present scenario as well as the technical details of tooth banking as related to SHED cells.

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09/11/2009 - Evaluation of pluripotency in human dental pulp cells
J Oral Maxillofac Surg. 2009 Mar;67(3):501-6

Koyama N, Okubo Y, Nakao K, Bessho K.

Department of Oral and Maxillofacial Surgery, Graduate School of Medicine, Kyoto University, Shogoin, Sakyo-ku, Kyoto, Japan.

PURPOSE: Postnatal stem cells have been isolated from various tissues, including bone marrow, neural tissue, skin, retina, and dental epithelium. Recently, adult stem cells have been isolated from human dental pulp. Postnatal stem cells have been isolated from a variety of tissues. Previously, it was generally accepted that the differentiation potential of postnatal stem cells was lineage restricted. MATERIALS AND METHODS: Normal impacted third molars were collected from adults and normal exfoliated deciduous teeth (SHED; stem cells from human exfoliated deciduous teeth) by single-colony selection and magnetic activated cell sorting. RESULTS: BMP-2 treatment groups produced alkaline phosphatase in the cells and also produced and secreted osteocalcin in the culture medium, and were capable of inducing an upregulated expression of Osteocalcin or Sox9, Col 2, and Col X by reverse transcriptase polymerase chain reaction (RT-PCR). For adipogenic differentiation, there is potential for SHED and dental pulp stem cells (DPSC) to express 2 adipocyte-specific transcripts, PPARgamma2 and LPL, in vitro, as do bone marrow mesenchymal stem cells by RT-PCR. CONCLUSION: This study demonstrated that pluripotential cells isolated from the pulp of human teeth expanded in vitro and differentiated into osteoblasts, chondrocytes, and adipocytes. DPSC and SHED are not only derived from a very accessible tissue resource but also capable of providing enough cells for potential clinical applications.

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09/11/2009 - Mesenchymal stem cells derived from dental tissues vs. those from other sources: their biology and role in regenerative medicine.
J Dent Res. 2009 Sep;88(9):792-806.

Huang GT, Gronthos S, Shi S.

University of Maryland, College of Dental Surgery, Dental School, Department of Endodontics, Prosthodontics and Operative Dentistry, 650 West Baltimore St., Baltimore, MD 21201, USA. ghuang@umaryland.edu

To date, 5 different human dental stem/progenitor cells have been isolated and characterized: dental pulp stem cells (DPSCs), stem cells from exfoliated deciduous teeth (SHED), periodontal ligament stem cells (PDLSCs), stem cells from apical papilla (SCAP), and dental follicle progenitor cells (DFPCs). These postnatal populations have mesenchymal-stem-cell-like (MSC) qualities, including the capacity for self-renewal and multilineage differentiation potential. MSCs derived from bone marrow (BMMSCs) are capable of giving rise to various lineages of cells, such as osteogenic, chondrogenic, adipogenic, myogenic, and neurogenic cells. The dental-tissue-derived stem cells are isolated from specialized tissue with potent capacities to differentiate into odontogenic cells. However, they also have the ability to give rise to other cell lineages similar to, but different in potency from, that of BMMSCs. This article will review the isolation and characterization of the properties of different dental MSC-like populations in comparison with those of other MSCs, such as BMMSCs. Important issues in stem cell biology, such as stem cell niche, homing, and immunoregulation, will also be discussed.

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09/05/2009 - Hepatic lineage differentiation of milk and third molar pulp cells

Paper: Hepatic lineage differentiation of milk and third molar pulp cells (IADR/AADR/CADR 87th General Session and Exhibition (April 1-4, 2009))

N. ISHKITIEV1, T. NAKAHARA1, T. SATO1, V. MITEV2, and K. YAEGAKI1, 1Nippon Dental University, Tokyo, Japan, 2Medical University - Sofia, Sofia, Bulgaria
Objectives: Stromal stem cells display extensive proliferative capacity of multilineage differentiation and offer a large therapeutic potential in the field of regenerative medicine. The stromal compartment of mesenchymal tissues is considered to harbor stem cells. The present study is a comparison of differentiation towards endodermal lineage properties of mesenchymal cell cultures from milk tooth pulp and third molar pulp.

Methods: Cell cultures were isolated from milk tooth and third molar pulp and were grown in DMEM supplemented with 10 % FBS. Cells were characterized for expressing stem cell markers CD117, CD44H, Oct3/4 by immunofluorescency and flow-cytometry. After 3 to 5 passages we added to the media 20 ng/ml hepatocyte growth factor (HGF) for 5 days for hepatic commitment. For hepatic differentiation the cells were cultured in DMEM, 20 ng/ml HGF, 10 nM dexamethasone, insulin-transferrin-selenium X, 10 ng/ml oncostatin and 2% FBS for 15 days.

Results: Both mesenchymal cell lines were proven to be positive for pluripotent cell markers CD117, CD44H, Oct3/4. After hepatic induction both cell types changed from spindle shaped, fibroblast like to polygonal, parenchimal-like morphology. The alpha feto-protein and albumin expression were found during the differentiating process by immunofluorescency and ELISA. Mesenchymal cells were expanded in vitro and maintained in an undifferentiated state for more than 50 population doublings. Thus the cells differentiated into cells with morphological, phenotypic, and functional characteristics of hepatocytes.

Conclusions: The present results demonstrated the ability of both wisdom and milk tooth pulp mesenchymal cell cultures to differentiate to endodermal type of cells, normally not presented in tooth's pulp. These cells also acquired functional characteristics of hepatocytes: they secreted alpha feto-protein. Dental pulp mesenchymal cells obtained from each patient, requiring liver transplantation may therefore be ideal for in vivo therapies for these patients.
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09/02/2009 - Isolation and characterization of stem cells derived from human third molar tooth germs of young adults: implications in neo-vascularization, osteo-, adipo- and neurogenesis.
Pharmacogenomics J. 2009 Sep 1

Yalvac ME, Ramazanoglu M, Rizvanov AA, Sahin F, Bayrak OF, Salli U, Palotás A, Kose GT.

Department of Genetics and BioEngineering, College of Engineering and Architecture, Yeditepe University, Kayisdagi, Istanbul, Turkey.

A number of studies have reported in the last decade that human tooth germs contain multipotent cells that give rise to dental and peri-odontal structures. The dental pulp, third molars in particular, have been shown to be a significant stem cell source. In this study, we isolated and characterized human tooth germ stem cells (hTGSCs) from third molars and assessed the expression of developmentally important transcription factors, such as oct4, sox2, klf4, nanog and c-myc, to determine their pluri-potency. Flow-cytometry analysis revealed that hTGSCs were positive for CD73, CD90, CD105 and CD166, but negative for CD34, CD45 and CD133, suggesting that these cells are mesenchymal-like stem cells. Under specific culture conditions, hTGSCs differentiated into osteogenic, adipogenic and neurogenic cells, as well as formed tube-like structures in Matrigel assay. hTGSCs showed significant levels of expression of sox2 and c-myc messenger RNA (mRNA), and a very high level of expression of klf4 mRNA when compared with human embryonic stem cells. This study reports for the first time that hTGSCs express developmentally important transcription factors that could render hTGSCs an attractive candidate for future somatic cell re-programming studies to differentiate germs into various tissue types, such as neurons and vascular structures. In addition, these multipotential hTGSCs could be important stem cell sources for autologous transplantation.The Pharmacogenomics Journal advance online publication, 1 September 2009; doi:10.1038/tpj.2009.40.

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07/27/2009 - Isolation and characterization of human dental pulp stem/stromal cells from nonextracted crown-fractured teeth requiring root canal therapy.
J Endod. 2009 May;35(5):673-81

Huang AH, Chen YK, Chan AW, Shieh TY, Lin LM.

Department of Oral Pathology, College of Dental Medicine, Kaohsiung Medical University, Taiwan.

INTRODUCTION: Human dental pulp stem/stromal cells (hDPSCs) in adults are primarily derived from the pulp tissues of permanent third molar teeth in existing literatures, whereas no reports exist, to our knowledge, on deriving hDPSCs from a tooth without the need for surgical procedure. The aim of this study was to raise a novel idea to source hDPSCs from complicated crown-fractured teeth requiring root canal therapy. METHODS: hDPSCs were harvested from the pulp tissues for two complicated crown-fractured teeth requiring root canal therapy, retaining the teeth for subsequent prosthodontic rehabilitation, in a 41-year-old woman who had suffered a motorcycle accident. Pulp tissue from the left lower deciduous canine of a healthy 10-year-old boy (the positive control) was also removed because of high mobility and cultured for hDPSCs. RESULTS: The hDPSCs derived from the two complicated crown-fractured teeth and the deciduous tooth were able to differentiate into adipogenic, chondrogenic, and osteogenic lineages and also expressed stem cells markers and differentiation markers, which indicated their stem cell origin and differentiation capability. In addition, hDPSCs from both the complicated crown-fractured teeth and the deciduous tooth showed high expression for bone marrow stem cell markers including CD29, CD90, and CD105 and exhibited very low expression of markers specific for hematopoietic cells such as CD14, CD34, and CD45. CONCLUSIONS: This report describes the successful isolation and characterization of hDPSCs from the pulp tissue of complicated crown-fractured teeth without tooth extraction. Therefore, pulp exposed in complicated crown-fractured teeth might represent a valuable source of personal hDPSCs.

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07/26/2009 - Somatic stem cells for regenerative dentistry.
Clin Oral Investig. 2008 Jun;12(2):113-8. Epub 2008 Jan 3.

Morsczeck C, Schmalz G, Reichert TE, Völlner F, Galler K, Driemel O.

Institute of Human Genetics, University of Regensburg, Regensburg, Germany. christian.morsczeck@klinik.uni-regensburg.de

Complex human tissues harbour stem cells and/or precursor cells, which are responsible for tissue development or repair. Recently, dental tissues such as periodontal ligament (PDL), dental papilla or dental follicle have been identified as easily accessible sources of undifferentiated cells. The dental stem cell biology might provide meaningful insights into the development of dental tissues and cellular differentiation processes. Dental stem cells could also be feasible tools for dental tissue engineering. Constructing complex structures like a periodontium, which provides the functional connection between a tooth or an implant and the surrounding jaw, could effectively improve modern dentistry. Dental precursor cells are attractive for novel approaches to treat diseases like periodontitis, dental caries or to improve dental pulp healing and the regeneration of craniofacial bone and teeth. These cells are easily accessible and, in contrast to bone-marrow-derived mesenchymal stem cells, are more closely related to dental tissues. This review gives a short overview of stem cells of dental origin.

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07/26/2009 - Phenotype and behaviour of dental pulp cells during expansion culture.
Arch Oral Biol. 2009 Jul 18.

Patel M, Smith AJ, Sloan AJ, Smith G, Cooper PR.

Oral Biology, The School of Dentistry, The University of Birmingham, St. Chads Queensway, Birmingham B4 6NN, UK.

OBJECTIVE: Primary pulp cell cultures are frequently used to study cellular responses, odontogenic potential and stem cell responses. Their isolation and expansion via a range of technical approaches are widely reported. The purpose of this study was to investigate the influence of isolation approach and extended expansion on cell phenotype and behaviour. DESIGN: To determine viable cell isolation, enzymatic dissociation was performed on rodent incisor pulps using collagenase, trypsin, hyaluronidase and ficin. Extended expansion culture of released cells was performed in DMEM and alpha-MEM media. Cultures were subsequently analysed for gene expression, cell proliferation, cell morphology and differentiation capacity up to passage 20. RESULTS: Data indicated that incubation of extirpated and mechanically minced rodent pulpal tissue with 0.25% Trypsin:EDTA and subsequent culture in alpha-MEM medium provided optimal conditions for maximal cell growth and expansion. Under these conditions, extended culture decreased cellular proliferative capacity up to passage 7, whilst higher passages demonstrated recovered growth rates. In general gene expression analysis of osteogenic and dentinogenic associated markers decreased with increasing passage number. Notably expression of TGFbetas-1, -2 and -3 increased up to passage 10 as did the stem cell and pericyte/myofibroblast markers, CD74, Neuroserpin and alpha-SMA. Analysis of molecular phenotypes indicated little difference in lineage differentiation capacity between earlier and later passages. CONCLUSIONS: The present study characterizes conditions for primary pulp cell isolation and expansion and indicates that both earlier and later passages maintain differentiation capacity. Continued passage however may result in selection for cells with a pericyte/myofibroblast phenotype.

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07/26/2009 - EXPLANT-DERIVED HUMAN DENTAL PULP STEM CELLS ENHANCE DIFFERENTIATION AND PROLIFERATION POTENTIALS.
J Cell Mol Med. 2009 Jul 7.

Spath L, Rotilio V, Alessandrini M, Gambara G, De Angelis L, Mancini M, Mitsiadis TA, Vivarelli E, Naro F, Filippini A, Papaccio G.

Department of Histology and Medical Embryology, University of Rome "La Sapienza", Rome, Italy.

Abstract Numerous stem cell niches are present in the different tissues and organs of the adult human body. Among these tissues, dental pulp, entrapped within the 'sealed niche' of the pulp chamber, is an extremely rich site for collecting stem cells. In this study, we demonstrate that the isolation of human dental pulp stem cells by the explants culture method (hD-DPSCs) allows the recovery of a population of dental mesenchymal stem cells that exhibit an elevated proliferation potential. Moreover, we highlight that hD-DPSCs are not only capable of differentiating into osteoblasts and chondrocytes but are also able to switch their genetic programme when co-cultured with murine myoblasts. High levels of MyoD expression were detected, indicating that muscle-specific genes in dental pulp cells can be turned on through myogenic fusion, confirming thus their multipotency. A perivascular niche may be the potential source of hD-DPSCs, as suggested by the consistent Ca(2+) release from these cells in response to endothelin-1 (ET-1) treatment, which is also able to significantly increase cell proliferation. Moreover, response to ET-1 has been found to be superior in hD-DPSCs than in DPSCs, probably due to the isolation method that promotes release of stem/progenitor cells from perivascular structures. The ability to isolate, expand and direct the differentiation of hD-DPSCs into several lineages, mainly towards myogenesis, offers an opportunity for the study of events associated with cell commitment and differentiation. Therefore, hD-DPSCs display enhanced differentiation abilities when compared to DPSCs, and this might be of relevance for their use in therapy.

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07/26/2009 - Gangliosides are involved in neural differentiation of human dental pulp-derived stem cells.
Biochem Biophys Res Commun. 2009 Jul 4.

Ryu JS, Ko K, Lee JW, Park SB, Byun SJ, Jeong EJ, Ko K, Choo YK.

Department of Biological Science, College of Natural Sciences, Wonkwang University, Iksan, Jeonbuk 570-749, Republic of Korea.

Human dental pulp-derived stem cells (hDPSCs) have been considered alternative sources of adult stem cells because of their potential to differentiate into multiple cell lineages. This study investigated the possible role of gangliosides in the neural differentiation of hDPSCs. When hDPSCs were cultured under neural differentiation conditions, expression of neural cell maker genes such as Nestin, MAP-2, and NeuN was detected. Immunostaining and high-performance thin-layer chromatography analysis showed that an increase in ganglioside biosynthesis was associated with neural differentiation of hDPSCs. Specifically, a significant increase in GD3 and GD1a expression was observed during neural differentiation. To confirm the role of gangliosides in neural differentiation, ganglioside biosynthesis was inhibited in hDPSCs by knockdown of UDP-glucose ceramide glucosyltransferase (Ugcg), which prevented differentiation into neural cells. These results suggest that gangliosides may play a role in the neural differentiation process of hDPSCs.

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07/26/2009 - A simple and efficient method for generating Nurr1-positive neuronal stem cells from human wisdom teeth (tNSC) and the potential of tNSC for stroke therapy.
Cytotherapy. 2009 Jul 3:1-12

Yang KL, Chen MF, Liao CH, Pang CY, Lin PY.

Tzu Chi Stem Cells Centre, Tzu Chi General Hospital, Hualien, Taiwan.

Background aims We have isolated human neuronal stem cells from exfoliated third molars (wisdom teeth) using a simple and efficient method. The cultured neuronal stem cells (designated tNSC) expressed embryonic and adult stem cell markers, markers for chemotatic factor and its corresponding ligand, as well as neuron proteins. The tNSC expressed genes of Nurr1, NF-M and nestin. They were used to treat middle cerebral artery occlusion (MCAO) surgery-inflicted Sprague-Dawley (SD) rats to assess their therapeutic potential for stroke therapy. Methods. For each tNSC cell line, a normal human impacted wisdom tooth was collected from a donor with consent. The tooth was cleaned thoroughly with normal saline. The molar was vigorously shaken or vortexed for 30 min in a 50-mL conical tube with 15-20 mL normal saline. The mixture of dental pulp was collected by centrifugation and cultured in a 25-cm(2) tissue culture flask with 4-5 mL Medium 199 supplemented with 5-10% fetal calf serum. The tNSC harvested from tissue culture, at a concentration of 1-2x10(5), were suspended in 3 microL saline solution and injected into the right dorsolateral striatum of experimental animals inflicted with MCAO. Results. Behavioral measurements of the tNSC-treated SD rats showed a significant recovery from neurologic dysfunction after MCAO treatment. In contrast, a sham group of SD rats failed to recover from the surgery. Immunohistochemistry analysis of brain sections of the tNSC-treated SD rats showed survival of the transplanted cells. Conclusions. These results suggest that adult neuronal stem cells may be procured from third molars, and tNSC thus cultivated have potential for treatment of stroke-inflicted rats.

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07/26/2009 - Simultaneous PKC and cAMP activation induces differentiation of human dental pulp stem cells into functionally active neurons.
Neurochem Int. 2009 Sep;55(5):323-32. Epub 2009 Apr 5

Király M, Porcsalmy B, Pataki A, Kádár K, Jelitai M, Molnár B, Hermann P, Gera I, Grimm WD, Ganss B, Zsembery A, Varga G.

Department of Oral Biology, Semmelweis University, Budapest, Hungary.

The plasticity of dental pulp stem cells (DPSCs) has been demonstrated by several studies showing that they appear to self-maintain through several passages, giving rise to a variety of cells. The aim of the present study was to differentiate DPSCs to mature neuronal cells showing functional evidence of voltage gated ion channel activities in vitro. First, DPSC cultures were seeded on poly-l-lysine coated surfaces and pretreated for 48h with a medium containing basic fibroblast growth factor and the demethylating agent 5-azacytidine. Then neural induction was performed by the simultaneous activation of protein kinase C and the cyclic adenosine monophosphate pathway. Finally, maturation of the induced cells was achieved by continuous treatment with neurotrophin-3, dibutyryl cyclic AMP, and other supplementary components. Non-induced DPSCs already expressed vimentin, nestin, N-tubulin, neurogenin-2 and neurofilament-M. The inductive treatment resulted in decreased vimentin, nestin, N-tubulin and increased neurogenin-2, neuron-specific enolase, neurofilament-M and glial fibrillary acidic protein expression. By the end of the maturation period, all investigated genes were expressed at higher levels than in undifferentiated controls except vimentin and nestin. Patch clamp analysis revealed the functional activity of both voltage-dependent sodium and potassium channels in the differentiated cells. Our results demonstrate that although most surviving cells show neuronal morphology and express neuronal markers, there is a functional heterogeneity among the differentiated cells obtained by the in vitro differentiation protocol described herein. Nevertheless, this study clearly indicates that the dental pulp contains a cell population that is capable of neural commitment by our three step neuroinductive protocol.

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07/26/2009 - Implanted Adult Human Dental Pulp Stem Cells Induce Endogenous Axon Guidance
Stem Cells 2009 Jun 4

Arthur A, Shi S, Zannettino AC, Fujii N, Gronthos S, Koblar SA.

Mesenchymal Stem Cell Group, Division of Haematology, Institute of Medical and Veterinary Science/Hanson Institute, CSCR University of Adelaide, Adelaide 5000, SA, Australia.

The human central nervous system has limited capacity for regeneration. Stem cell-based therapies may overcome this through cellular mechanisms of neural replacement and/or through molecular mechanisms, whereby secreted factors induce change in the host tissue. A readily accessible human cell population to investigate these mechanisms are dental pulp progenitor/stem cells (DPSC) that can differentiate into functionally active neurons given the appropriate environmental cues. We hypothesized that implanted DPSC secrete factors that coordinate axon guidance within a receptive host nervous system. An avian embryonic model system was adapted to investigate axon guidance in vivo following transplantation of adult human DPSC. Chemo-attraction of avian trigeminal ganglion axons towards implanted DPSC was mediated via the chemokine, CXCL12, also known as stromal cell derived factor-1, and its receptor, CXCR4. These findings provide the first direct evidence that DPSC may induce neuroplasticity within a receptive host nervous system.

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07/26/2009 - Identification of novel epithelial stem cell-like cells in human deciduous dental pulp.
Biochem Biophys Res Commun. 2009 Aug 14;386(1):135-9

Nam H, Lee G.

Laboratory of Molecular Genetics and Stem Cell Differentiation, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-749, Republic of Korea.

It is well known that interactions between epithelial components and mesenchymal components are essential for tooth development. Therefore, it has been postulated that both types of stem cells might be involved in the regeneration of dental hard tissues. Recently, mesenchymal dental pulp stem cells that have odontogenic potential were identified from human dental pulp. However, the existence of epithelial cells has never been reported in human dental pulp. In the present study, we isolated and characterized epithelial cell-like cells from human deciduous dental pulp. They had characteristic epithelial morphology and expressed epithelial markers. Moreover, they expressed epithelial stem cell-related genes such as ABCG2, Bmi-1, DeltaNp63, and p75. Taken together, our findings suggest that epithelial stem cell-like cells might exist in human deciduous dental pulp and might play a role as an epithelial component for the repair or regeneration of teeth.

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07/26/2009 - Hypoxia-amplified proliferation of human dental pulp cells
J Endod. 2009 Jun;35(6):818-23.

Sakdee JB, White RR, Pagonis TC, Hauschka PV.

Department of Restorative Dentistry, Harvard School of Medicine, Boston, MA 02115, USA. bjsakdee@post.harvard.edu

INTRODUCTION: Postnatal human dental pulp is a potentially promising source of progenitor cells. Sustaining and amplifying progenitor cell populations would be beneficial for basic science research with application in pulpal regeneration. Hypoxia has been observed to promote the undifferentiated cell state in various stem cell populations. The purpose of this study was to examine human dental pulp cells (DPCs) proliferation in normoxia and hypoxia. METHODS: Dental pulp cells were obtained from third molars of adult patients and cultured in alpha modification of Eagle's medium culture medium with 10% fetal bovine serum. For cell proliferation, DPCs were divided into two groups: (1) DPCs incubated in normoxic conditions (20% oxygen tension) and (2) DPC incubated in hypoxic conditions (3% oxygen tension). Cell proliferation assays were performed every 2 to 3 days from day 3 to day 14 by trypsinization and quantification of cells with a hemacytometer. Fluorescence-activated cell sorting analysis was completed to investigate stem cell markers, CD133, and STRO-1. RESULTS: DPCs proliferated significantly more in hypoxia than in normoxia (ie, two-fold throughout the experiment, p < 0.0001). The primitive stem cell marker, CD133, decreased in hypoxia, whereas the osteoprogenitor marker, STRO-1, increased by 8.5-fold. CONCLUSIONS: This study suggested that hypoxia is an effective treatment to amplify numbers of progenitor cells from human dental pulp.

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06/16/2009 - Optimized Cryopreservation Method for Human Dental Pulp-Derived Stem Cells and their Tissues of origin for banking and Clinical Use.

OPTIMIZED CRYOPRESERVATION METHOD FOR HUMAN DENTAL PULP-DERIVED STEM CELLS AND THEIR TISSUES OF ORIGIN FOR BANKING AND CLINICAL USE

Erik J. Woods, Brandon C. Perry, J. Jeffrey Hockema, Lindsay Larson, Dan Zhou, and W. Scott Goebel

ABSTRACT

Dental pulp is a promising source of mesenchymal stem cells with the potential for cell-mediated therapies and tissue engineering applications. We recently reported that isolation of dental pulp-derived stem cells (DPSC) is feasible for at least 120 hours after tooth extraction, and that cryopreservation of early-passage cultured DPSC leads to high-efficiency recovery post thaw. This study investigated additional processing and cryobiological characteristics of DPSC, ending with development of procedures for banking. First, we aimed to optimize cryopreservation of established DPSC cultures, with regards to optimizing the cryoprotective agent (CPA), the CPA concentration, the concentration of cells frozen, and storage temperatures. Secondly, we focused on determining cryopreservation characteristics of enzymatically digested tissue as a cell suspension. Lastly, we evaluated the growth, surface markers and differentiation properties of DPSC obtained from intact teeth and undigested, whole dental tissue frozen and thawed using the optimized procedures. In these experiments it was determined that Me2SO at a concentration between 1 and 1.5M was the ideal cryopreservative of the three studied. It was also determined that DPSC viability after cryopreservation is not limited by the concentration of cells frozen, at least up to 2 × 106 cells/mL. It was further established that DPSC can be stored at ?85°C or ?196°C for at least six months without loss of functionality. The optimal results with the least manipulation were achieved by isolating and cryopreserving the tooth pulp tissues, with digestion and culture performed post-thaw. A recovery of cells from >85% of the tissues frozen was achieved and cells isolated post thaw from tissue processed and frozen with a serum free, defined cryopreservation medium maintained morphological and developmental competence and demonstrated MSC-hallmark trilineage differentiation under the appropriate culture conditions.

Read More:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2757034/

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03/03/2009 - Human Dental Pulp Stem Cells: From Biology to Clinical Applications
It has been reported that these cells can be easily cryopreserved and stored for long periods of time and still retain their multipotency and tissue-producing capacity.  Benefits (1) dental pulp is a remarkable site of stem cells; (2) collecting stem cells from dental pulp is a noninvasive practice that can be performed in the adult during life and in the young after surgical extraction of wisdom teeth, a common surgical practice; (3) tissue sacrifice is very low when collecting dental pulp stem cells; (4)several cytotypes can be obtained from dental pulp stem cells owing to their multipotency; (5)transplantation of new-formed bone tissue obtained from dental pulp stem cells leads to the formation of vascularized adult bone and integration between the graft and the surrounding host blood supply; (6) dental pulp stem cells can be cryopreserved and stored for long periods; (7)dental pulp is ideal for tissue engineering and for clinical use in several pathologies requiring bone tissue growth and repair. In addition, tooth extraction is a clinical/therapeutical need. If bone marrow is the site of first choice for hematopoietic stem cell collection, dental pulp must be considered one of the major sites for mesenchymal cell collection. The good results obtained up to now reinforce this thought.
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02/06/2009 - Dental pulp stem cells: what, where, how?
Int J Paediatr Dent. 2009 Jan;19(1):61-70

Sloan AJ, Waddington RJ.

Mineralised Tissue Research Group, Tissue Engineering and Regenerative Dentistry, School of Dentistry Cardiff University, Cardiff, UK. sloanaj@cardiff.ac.uk

INTRODUCTION: It is now accepted that progenitor/stem cells reside within the post-natal dental pulp. Studies have identified several niches of multipotent mesenchymal progenitor cells, known as dental pulp stem cells, which have a high proliferative potential for self-renewal. These progenitor stem cells are now recognized as being vital to the dentine regeneration process following injury. Understanding the nature of these progenitor/stem cell populations in the pulp is important in determining their potentialities and development of isolation or recruitment strategies for use in regeneration and tissue engineering. Characterization of these cells, and determination of their potentialities in terms of specificity of regenerative response, may help direct new clinical treatment modalities. Such novel treatments may involve controlled direct recruitment of the cells in situ and possible seeding of stem cells at sites of injury for regeneration or use of the stem cells with appropriate scaffolds for tissue engineering solutions. Such approaches may provide an innovative and novel biologically based new generation of clinical materials and/or treatments for dental disease. AIM: This study aimed to review the body of knowledge relating to stem cells and to consider the possibility of these cell populations, and related technology, in future clinical applications.

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02/06/2009 - Isolation of distinct progenitor stem cell populations from dental pulp.
Cells Tissues Organs. 2009;189(1-4):268-74. Epub 2008 Aug 14

Waddington RJ, Youde SJ, Lee CP, Sloan AJ.

Tissue Engineering and Reparative Dentistry, School of Dentistry, Cardiff University, Cardiff, UK. waddingtonrj@cardiff.ac.uk

The present study compared the cellular characteristics of progenitor stem cell populations present in adult dental pulp, isolated by different methods utilizing 2 different features of stem cell biology. One population expressing high levels of beta1 integrin was isolated by preferential selection of adherent cells to fibronectin over 20 min. In an alternative approach, cells expressing the embryonic neural crest cell marker, low-affinity nerve growth factor receptor (LANGFR), were selected by magnetic-activated cell sorting. For each method, clonal cell lines were established and expanded in culture. One clone derived via the respective methods was examined for embryonic/progenitor cell markers by immunocytochemistry and RT-PCR. Both clonal populations demonstrated the expression of stro-1 and stained positive for vimentin, demonstrating mesenchymal lineage. Of note, cells selected for LANGFR cells demonstrated the additional expression of CD105 and Notch 2. For both clonal populations, expanded cultures demonstrated the ability to differentiate into osteoblasts, adipocytes and chondrocytes. These results would suggest the potential isolation of 2 progenitor cell populations exhibiting different cellular characteristics in terms of their embryonic nature. The potential for both cell populations to derive from a common origin is discussed. Copyright 2008 S. Karger AG, Basel.

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02/06/2009 - Somatic stem cells for regenerative dentistry.
Clin Oral Investig. 2008 Jun;12(2):113-8. Epub 2008 Jan 3

Morsczeck C, Schmalz G, Reichert TE, Völlner F, Galler K, Driemel O.

Institute of Human Genetics, University of Regensburg, Regensburg, Germany. christian.morsczeck@klinik.uni-regensburg.de

Complex human tissues harbour stem cells and/or precursor cells, which are responsible for tissue development or repair. Recently, dental tissues such as periodontal ligament (PDL), dental papilla or dental follicle have been identified as easily accessible sources of undifferentiated cells. The dental stem cell biology might provide meaningful insights into the development of dental tissues and cellular differentiation processes. Dental stem cells could also be feasible tools for dental tissue engineering. Constructing complex structures like a periodontium, which provides the functional connection between a tooth or an implant and the surrounding jaw, could effectively improve modern dentistry. Dental precursor cells are attractive for novel approaches to treat diseases like periodontitis, dental caries or to improve dental pulp healing and the regeneration of craniofacial bone and teeth. These cells are easily accessible and, in contrast to bone-marrow-derived mesenchymal stem cells, are more closely related to dental tissues. This review gives a short overview of stem cells of dental origin.

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12/20/2008 - Human dental pulp stem cells: from biology to clinical applications.
J Exp Zoolog B Mol Dev Evol. 2008 Dec 8

d'Aquino R, De Rosa A, Laino G, Caruso F, Guida L, Rullo R, Checchi V, Laino L, Tirino V, Papaccio G.

Dipartimento di Medicina Sperimentale, Sezione di Istologia ed Embriologia, TESLab, Secondo Ateneo di Napoli, Napoli, Italy.

Dental pulp stem cells (DPSCs) can be found within the "cell rich zone" of dental pulp. Their embryonic origin, from neural crests, explains their multipotency. Up to now, two groups have studied these cells extensively, albeit with different results. One group claims that these cells produce a "dentin-like tissue", whereas the other research group has demonstrated that these cells are capable of producing bone, both in vitro and in vivo. In addition, it has been reported that these cells can be easily cryopreserved and stored for long periods of time and still retain their multipotency and bone-producing capacity. Moreover, recent attention has been focused on tissue engineering and on the properties of these cells: several scaffolds have been used to promote 3-D tissue formation and studies have demonstrated that DPSCs show good adherence and bone tissue formation on microconcavity surface textures. In addition, adult bone tissue with good vascularization has been obtained in grafts. These results enforce the notion that DPSCs can be used successfully for tissue engineering. J. Exp. Zool. (Mol. Dev. Evol.) 310B, 2008. (c) 2008 Wiley-Liss, Inc.

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12/16/2008 - Isolation of distinct progenitor stem cell populations from dental pulp
Cells Tissues Organs. 2009;189(1-4):268-74. Epub 2008 Aug 14

Waddington RJ, Youde SJ, Lee CP, Sloan AJ.

Tissue Engineering and Reparative Dentistry, School of Dentistry, Cardiff University, Cardiff, UK. waddingtonrj@cardiff.ac.uk

The present study compared the cellular characteristics of progenitor stem cell populations present in adult dental pulp, isolated by different methods utilizing 2 different features of stem cell biology. One population expressing high levels of beta1 integrin was isolated by preferential selection of adherent cells to fibronectin over 20 min. In an alternative approach, cells expressing the embryonic neural crest cell marker, low-affinity nerve growth factor receptor (LANGFR), were selected by magnetic-activated cell sorting. For each method, clonal cell lines were established and expanded in culture. One clone derived via the respective methods was examined for embryonic/progenitor cell markers by immunocytochemistry and RT-PCR. Both clonal populations demonstrated the expression of stro-1 and stained positive for vimentin, demonstrating mesenchymal lineage. Of note, cells selected for LANGFR cells demonstrated the additional expression of CD105 and Notch 2. For both clonal populations, expanded cultures demonstrated the ability to differentiate into osteoblasts, adipocytes and chondrocytes. These results would suggest the potential isolation of 2 progenitor cell populations exhibiting different cellular characteristics in terms of their embryonic nature. The potential for both cell populations to derive from a common origin is discussed. Copyright 2008 S. Karger AG, Basel.

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11/02/2008 - Putative dental pulp-derived stem/stromal cells promote proliferation and differentiation of endogenous neural cells in the hippocampus of mice
Stem Cells 2008 Oct;26(10):2654-63. Epub 2008 Aug

Huang AH, Snyder BR, Cheng PH, Chan AW

Grace Dental Clinic, Kaohsiung City, Taiwan

Until now, interest in dental pulp stem/stromal cell (DPSC) research has centered on mineralization and tooth repair. Beginning a new paradigm in DPSC research, we grafted undifferentiated, untreated DPSCs into the hippocampus of immune-suppressed mice. The rhesus DPSC (rDPSC) line used was established from the dental pulp of rhesus macaques and found to be similar to human bone marrow/mesenchymal stem cells, which express Nanog, Rex-1, Oct-4, and various cell surface antigens, and have multipotent differentiation capability. Implantation of rDPSCs into the hippocampus of mice stimulated proliferation of endogenous neural cells and resulted in the recruitment of pre-existing Nestin(+) neural progenitor cells (NPCs) and beta-tubulin-III(+) mature neurons to the site of the graft. Additionally, many cells born during the first 7 days after implantation proliferated, forming NPCs and neurons, and, to a lesser extent, underwent astrogliosis, forming astrocytes and microglia, by 30 days after implantation. Although the DPSC graft itself was short term, it had long-term effects by promoting growth factor signaling. Implantation of DPSCs enhanced the expression of ciliary neurotrophic factor, vascular endothelial growth factor, and fibroblast growth factor for up to 30 days after implantation. In conclusion, grafting rDPSCs promotes proliferation, cell recruitment, and maturation of endogenous stem/progenitor cells by modulating the local microenvironment. Our results suggest that DPSCs have a valuable, unique therapeutic potential, specifically as a stimulator and modulator of the local repair response in the central nervous system. DPSCs would be a preferable cell source for therapy due to the possibility of a "personalized" stem cell, avoiding the problems associated with host immune rejection. Disclosure of potential conflicts of interest is found at the end of this article.

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11/02/2008 - Human periodontal ligament: a niche of neural crest stem cells.
J Periodontal Res. 2008 Oct;43(5):531-6. Epub 2008 Jul 4

Coura GS, Garcez RC, de Aguiar CB, Alvarez-Silva M, Magini RS, Trentin AG.

Departamento de Estomatologia, Centro de Ciências da Saúde, Universidade Federal de Santa Catarina, Brazil. gustavocoura@hotmail.com

BACKGROUND AND OBJECTIVE: The periodontal ligament is a specialized connective tissue, derived from dental follicle and originated from neural crest cells. Recently it has been suggested, based on animal models, that periodontal ligament could be a niche for neural crest stem cells. However, there is still little knowledge on this subject. The identification of neural crest adult stem cells has received much attention based on its potential in tissue regeneration. The objective of the present work was to verify the human periodontal ligament as a niche for neural crest stem cells. MATERIAL AND METHODS: Cells from human periodontal ligament were isolated from 10 teeth of seven individuals (periodontal ligament pool group) and also from four teeth of one individual (periodontal ligament single group), after enzymatic digestion. The cells were cultured in specific inductive medium. Analyses of protein and gene expression were performed through immunocytochemistry and reverse transcription-polymerase chain reaction techniques, respectively. RESULTS: Mesodermal phenotypes (adipogeneic, osteogenic and myofibroblastic) were identified after culture in inductive medium. Immunocytochemistry analyses showed the presence of the nestin marker of neural stem cells and also markers of undifferentiated neural crest cells (HNK1, p75). When cultured in inductive medium that allowed neural differentiation, the cells showed markers for beta-tubulin III, neurofilament M, peripherin, microtubule-associated protein 2 and protein zero. The results were similar between the two study groups (the periodontal ligament pool group and the periodontal ligament single group). CONCLUSION: This research provides evidence that human periodontal ligament, in addition to its mesodermal derivatives, produces neural crest-like cells. Such features suggest a recapitulation of their embryonic state. The human periodontal ligament revealed itself as a viable alternative source for possible primitive precursors to be used in stem-cell therapies.

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07/05/2008 - A Novel Stem Cell Source for Vasculogenesis in Ischemia: Subfraction of Side Population Cells from Dental Pulp
Stem Cells 2008 Jun 26

Iohara K, Zheng L, Wake H, Ito M, Nabekura J, Wakita H, Nakamura H, Into T, Matsusita K, Nakashima M.

Department of Oral Disease Research, National Institute for Longevity Sciences, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8522, Japan.

Cell therapy with stem cells and endothelial progenitor cells (EPCs) to stimulate vasculogenesis as a potential treatment for ischemic disease is an exciting area of research in regenerative medicine. EPCs are present in bone marrow, peripheral blood, and adipose tissue. Autologous EPCs, however, are obtained by invasive biopsy, a potentially painful procedure. An alternative approach is proposed in this investigation. Permanent and deciduous pulp tissue is easily available from teeth after extraction without ethical issues and has potential for clinical use. We isolated a highly vasculogenic subfraction of side population (SP) cells based on CD31 and CD146, from dental pulp. The CD31(-);CD146(-) SP cells, demonstrating CD34(+) and VEGFR2/Flk1(+), were similar to EPCs. These cells were distinct from the hematopoietic lineage as CD11b, CD14, and CD45 mRNA were not expressed. They showed high proliferation and migration activities and multi-lineage differentiation potential including vasculogenic potential. In models of mouse hindlimb ischemia, local transplantation of this subfraction of SP cells resulted in successful engraftment and an increase in the blood flow including high density of capillary formation. The transplanted cells were in proximity of the newly formed vasculature and expressed several proangiogenic factors, such as VEGF-A, G-CSF, GM-CSF and MMP3. Conditioned medium from this subfraction showed the mitogenic and anti-apoptotic activity on human umbilical vein endothelial cells (HUVECs). In conclusion, subfraction of SP cells from dental pulp is a new stem cell source for cell-based therapy to stimulate angiogenesis/vasculogenesis during tissue regeneration.
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07/03/2008 - Defining properties of neural crest-derived progenitor cells from the apex of human developing tooth
Tissue Eng Part A. 2008 Feb;14(2):317-30

Degistirici O, Jaquiery C, Schönebeck B, Siemonsmeier J, Götz W, Martin I, Thie M.

Center of Advanced European Studies and Research, Bonn, Germany. degistirici@caesar.de

The connective tissue of the human tooth arises from cells that are derived from the cranial neural crest and, thus, are termed as "ectomesenchymal cells." Here, cells being located in a pad-like tissue adjacent to the apex of the developing tooth, which we designated the third molar pad, were separated by the microexplant technique. When outgrowing from the explant, dental neural crest-derived progenitor cells (dNC-PCs) adhered to plastic, proliferated steadily, and displayed a fibroblast-like morphology. At the mRNA level, dNC-PCs expressed neural crest marker genes like Sox9, Snail1, Snail2, Twist1, Msx2, and Dlx6. Cytofluorometric analysis indicated that cells were positive for CD49d (alpha4 integrin), CD56 (NCAM), and PDGFRalpha, while negative for CD31, CD34, CD45, and STRO-1. dNC-PCs could be differentiated into neurogenic, chondrogenic, and osteogenic lineages and were shown to produce bone matrix in athymic mice. These results demonstrate that human third molar pad possesses neural crest-derived cells that represent multipotent stem/progenitor cells. As a rather large amount of dNC-PCs could be obtained from each single third molar, cells may be used to regenerate a wide range of tissues within the craniofacial region of humans.

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07/02/2008 - Effects of FGF2 and TGFbeta(1) on the differentiation of human dental pulp stem cells in vitro
Cell Biol Int. 2008 Jul;32(7):827-34. Epub 2008 Mar 29

He H, Yu J, Liu Y, Lu S, Liu H, Shi J, Jin Y.

Department of Stomatology, Chinese PLA General Hospital and Postgraduate Military Medical School, Beijing 100853, China; Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.

Two crucial growth factors, FGF2 and TGFbeta(1), were investigated in this study to determine their inductive effects on the odontoblastic differentiation of human dental pulp stem cells (DPSCs) in vitro. DPSCs were isolated by immunomagnetic bead selection using the STRO-1 antibody, and then co-cultured respectively with FGF2, TGFbeta(1) and FGF2+TGFbeta(1). The results showed that FGF2 can exert a significant effect on the cell proliferation, while TGFbeta(1) or FGF2+TGFbeta(1) can initiate an odontoblast-like differentiation of DPSCs. Moreover, FGF2 can synergistically upregulate the effects of TGFbeta(1) on the odontoblastic differentiation of DPSCs, as indicated by the increased alkaline phosphatase activity, the polarized cell appearance and secretary ultrastructural features, the formation of mineralized nodules and the gene/protein expression of dentin sialoprotein and dentin matrix protein-1. Together, FGF2 acted primarily on the cell proliferation, while TGFbeta(1) and FGF2+TGFbeta(1) mainly stimulated the odontoblastic differentiation of DPSCs. This study provides interesting progress in the odontoblastic differentiation of DPSCs induced by FGF2 and TGFbeta(1).

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07/01/2008 - Human maxillary tuberosity and jaw periosteum as sources of osteoprogenitor cells for tissue engineering.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007 Nov;104(5):618.e1-12.
Epub 2007 Jul 5

Cicconetti A, Sacchetti B, Bartoli A, Michienzi S, Corsi A, Funari A, Robey PG, Bianco P, Riminucci M.

Departamento di Scienze Odontostomatologiche, Universitá La Sapienze, Romae, Italy.

OBJECTIVE: Bone tissue engineering is a promising approach for bone reconstruction in oral-maxillofacial surgery. This study investigates the suitability of oral skeletal tissues as convenient and accessible sources of osteogenic progenitors as an alternative to the iliac crest bone marrow. STUDY DESIGN: Samples of maxilla tuberosity (MT) and maxillary and mandibular periosteum (MP) were obtained during routine oral surgery, and donor site morbidity was assessed using a "split-mouth" approach. Cells isolated from MT (bone marrow stromal cells; MT-BMSCs) and from MP (periosteal cells; M-PCs), were analyzed for clonogenicity, phenotype, expression of osteogenic markers, and ability to form bone in vivo. RESULTS: Both MT-BMSCs and M-PCs included clonogenic cells, showed comparable phenotypic profiles, and expressed early osteogenic markers. Most importantly, both cell populations formed bone upon ectopic in vivo transplantation. CONCLUSION: MT-BMSCs and M-PCs behaved as osteoprogenitor cells in vitro and in vivo. MT and MP may be considered as suitable sources of cells for bone tissue engineering in humans.

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07/01/2008 - Characterization of dental pulp stem cells of human tooth germs.
J Dent Res. 2008 Jul;87(7):676-81

Takeda T, Tezuka Y, Horiuchi M, Hosono K, Iida K, Hatakeyama D, Miyaki S, Kunisada T, Shibata T, Tezuka K.

Department of Oral and Maxillofacial Science and.

In previous studies, human dental pulp stem cells (hDPSCs) were mainly isolated from adults. In this present study, we characterized hDPSCs isolated from an earlier developmental stage to evaluate the potential usage of these cells for tissue-regenerative therapy. hDPSCs isolated at the crown-completed stage showed a higher proliferation rate than those isolated at a later stage. When the cells from either group were cultured in medium promoting differentiation toward cells of the osteo/odontoblastic lineage, both became alkaline-phosphatase-positive, produced calcified matrix, and were also capable of forming dentin-like matrix on scaffolds in vivo. However, during long-term passage, these cells underwent a change in morphology and lost their differentiation ability. The results of a DNA array experiment showed that the expression of several genes, such as WNT16, was markedly changed with an increasing number of passages, which might have caused the loss of their characteristics as hDPSCs.

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07/01/2008 - Multilineage potential of pulp stem cells from human young permanent teeth in vitro
Beijing Da Xue Xue Bao. 2007 Feb 18;39(1):41-5

Liu HS, Bai XW, Yang Y, Ge LH.

Department of Pediatric Dentistry, Peking University School & Hospital of Stomatology, Beijing 100081, China.

OBJECTIVE: To isolate and culture the pulp cells from human young permanent teeth (pDPC), and to observe their biological characteristics and the expression of some specific markers, and to induce these pulp cells to differentiate into osteoblast, adipocyte, neuron and chondrocyte lineages. METHODS: Pulp cells were isolated and cultured from orthodontic extracted premolars of children. The attached cells after at least 3 passages were used for the following experiments: 1. Morphology and ultrastructure analysis; 2. Cell cycle and phenotype were analyzed by flowcytometry; 3. Growth curve were recorded; 4. pDPC were induced to differentiate into osteoblast, adipocyte, neuron in vitro, and were identified by histochemical methods and RT-PCR. RESULTS: 1. Attached pDPCs were fibroblast-like cells, which were distinguished from BMSC. 2. The cell organs in dDPCs were well developed. 3. pDPCs were highly positive for CD90, CD44, CD147, which are mesenchymal stem-cell markers, but were negative for other markers including CD34, CD38, CD45, HLA-DR. 4. pDPCs showed high growth rate. 5. pDPCs could be induced to differentiate into osteoblast, adipocyte, and neuron lineages, but not chondrocyte lineages. CONCLUSION: pDPCs were characterized by their ability to proliferate with high growth rate in vitro. The expression of some BMSC markers in these cells were observed. They showed the potential to differentiate into multiple mesenchymal lineages such as osteoblast, adipocyte, neuron lineages under specific conditions in vitro.

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06/17/2008 - Adult Human Dental Pulp Stem Cells Differentiate Towards Functionally Active Neurons Under Appropriate Environmental Cues
Stem Cells: First published online May 22, 2008

Agnes Arthur , Grigori Rychkov , Songtao Shi , Simon Andrea Koblar , Stan Gronthos

Human adult dental pulp stem cells (DPSC) reside within the perivascular niche of dental pulp and are thought to originate from migrating cranial neural crest (CNC) cells. During embryonic development, CNC cells differentiate into a wide variety of cell types including neurons of the peripheral nervous system. Previously, we have demonstrated that DPSC derived from adult human third molar teeth differentiate into cell types reminiscent of CNC embryonic ontology. We hypothesized that DPSC exposed to the appropriate environmental cues would differentiate into functionally active neurons. The data demonstrated that ex vivo expanded human adult DPSC responded to neuronal inductive conditions both in vitro and in vivo. Human adult DPSC, but not human foreskin fibroblasts (HFF) acquired a neuronal morphology, and expressed neuronal specific markers at both the gene and protein levels. Culture expanded DPSC also exhibited the capacity to produce a sodium current consistent with functional neuronal cells when exposed to neuronal inductive media. Furthermore, the response of human DPSC and HFF to endogenous neuronal environmental cues was determined in vivo using an avian xeno-transplantation assay. DPSC expressed neuronal markers and acquired a neuronal morphology following transplantation into the mesencephalon of embryonic day two chicken embryo, while HFF maintained a thin spindle fibroblastic morphology. We propose that adult human DPSC provide a readily accessible source of exogenous stem/precursor cells which have the potential for use in cell therapeutic paradigms to treat neurological disease.
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06/12/2008 - Human dental pulp stem cells differentiate into neural crest- derived melanocytes and have label-retaining and sphere-forming abilities
Stem Cells Dev. 2008 Mar 25

Inserm, JPA Center, Inserm U837, Lille, cedex, France; gaelique.stevens@wanadoo.fr.

Adult tissues contain highly proliferative, clonogenic cells that meet criteria of multipotent stem cells and are potential sources for autologous reparative and reconstructive medicine. We demonstrated that human dental pulp contains self renewing human dental pulp stem cells (hDPSCs) capable of differentiating into mesenchymal-derived odontoblasts, osteoblasts, adipocytes, chondrocytes and striated muscle, and interestingly, also into non-mesenchymal melanocytes. Furthermore, we showed that hDPSC cultures include cells with the label-retaining and sphere-forming abilities, traits attributed to multipotent stem cells, and provide evidence that these might be multipotent neural crest stem cells.

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06/04/2008 - Wnt/beta-catenin inhibits dental pulp stem cell differentiation.
J Dent Res. 2008 Feb;87(2):126-30

Scheller EL, Chang J, Wang CY.

Laboratory of Molecular Signaling, Department of Biologic and Materials Sciences, School of Dentistry, The University of Michigan, Ann Arbor, MI 48109, USA.

Dental pulp stem cells (DPSCs) are a unique precursor population isolated from postnatal human dental pulp and have the ability to regenerate a reparative dentin-like complex. Canonical Wnt signaling plays a critical role in tooth development and stem cell self-renewal through beta-catenin. In this study, the regulation of odontoblast-like differentiation of DPSCs by canonical Wnt signaling was examined. DPSCs were stably transduced with canonical Wnt-1 or the active form of beta-catenin, with retrovirus-mediated infection. Northern blot analysis found that Wnt-1 strongly induced the expression of matricellular protein osteopontin, and modestly enhanced the expression of type I collagen in DPSCs. Unexpectedly, Wnt-1 inhibited alkaline phosphatase (ALP) activity and the formation of mineralized nodules in DPSCs. Moreover, over-expression of beta-catenin was also sufficient to suppress the differentiation and mineralization of DPSCs. In conclusion, our results suggest that canonical Wnt signaling negatively regulates the odontoblast-like differentiation of DPSCs.

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06/03/2008 - SHED: stem cells from human exfoliated deciduous teeth.
Proc Natl Acad Sci U S A. 2003 May 13;100(10):5807-12. Epub 2003 Apr 25

Miura M, Gronthos S, Zhao M, Lu B, Fisher LW, Robey PG, Shi S.

Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.

To isolate high-quality human postnatal stem cells from accessible resources is an important goal for stem-cell research. In this study we found that exfoliated human deciduous tooth contains multipotent stem cells [stem cells from human exfoliated deciduous teeth (SHED)]. SHED were identified to be a population of highly proliferative, clonogenic cells capable of differentiating into a variety of cell types including neural cells, adipocytes, and odontoblasts. After in vivo transplantation, SHED were found to be able to induce bone formation, generate dentin, and survive in mouse brain along with expression of neural markers. Here we show that a naturally exfoliated human organ contains a population of stem cells that are completely different from previously identified stem cells. SHED are not only derived from a very accessible tissue resource but are also capable of providing enough cells for potential clinical application. Thus, exfoliated teeth may be an unexpected unique resource for stem-cell therapies including autologous stem-cell transplantation and tissue engineering.


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06/01/2008 - Comparison Between Genetic Portraits of Osteoblasts Derived From Primary Cultures and Osteoblasts Obtained From Human Pulpar Stem Cells
Journal of Craniofacial Surgery. 19(3):616-625, May 2008.

Carinci, Francesco MD *; Papaccio, Gianpaolo MD +; Laino, Gregorio MD ++; Palmieri, Annalisa PhD [S]; Brunelli, Giorgio MD *; D'Aquino, Riccardo DDS ++; Graziano, Antonio DDS ++; Lanza, Vladimiro MD ++; Scapoli, Luca PhD [S]; Martinelli, Marcella PhD [S]; Pezzetti, Furio PhD [S]

Abstract:
Harvesting bone for autologous grafting is a daily problem encountered by craniofacial and oral surgeons. Stem cells derived from human dental pulp are able to differentiate in osteoblasts and are a potential source of autologous bone produced in vitro. However, as stem cells are characterized by self-renewing and commitment in several cellular subtypes (ie, pluripotential differentiation), some concerns may arise as regards their potential uncontrolled proliferation.

To screen the behavior of osteoblasts derived from human pulpar stem cells (ODHPSCs), we used microarray techniques to identify genes that are differently regulated in ODHPSC in comparison to normal osteoblasts (NOs). Osteoblasts derived from human pulpar stem cells were obtained from human dental pulp, and cells were selected using a cytometer. The cell profile was c-kit+/CD34+/STRO-1+/CD45-. These cells were capable of differentiation of osteoblasts in vitro.

By using DNA microarrays containing 19,200 genes, we identified in ODHPSC some genes whose expression was significantly up- and downregulated compared to NO. The differentially expressed genes have different functional activities: (a) cell differentiation, (b) developmental maturation, (c) cell adhesion, and (d) production of cytoskeleton elements.

Thus, some molecular differences exist between NO and ODHPSC, although the previously considered histologic parameters show a normal phenotype
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05/17/2008 - Isolation and characterization of a population of immature dental pulp stem cells expressing OCT-4 and other embryonic stem cell markers.
Cells Tissues Organs. 2006;184(3-4):105-16

Kerkis I, Kerkis A, Dozortsev D, Stukart-Parsons GC, Gomes Massironi SM, Pereira LV, Caplan AI, Cerruti HF.

Laboratório de Genética, Instituto Butantan, São Paulo, Brasil. ikerkis@butantan.gov.br

We report the isolation of a population of immature dental pulp stem cells (IDPSC), which express embryonic stem cell markers Oct-4, Nanog, SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81 as well as several other mesenchymal stem cell markers during at least 25 passages while maintaining the normal karyotype and the rate of expansion characteristic of stem cells. The expression of these markers was maintained in subclones obtained from these cells. Moreover, in vitrothese cells can be induced to undergo uniform differentiation into smooth and skeletal muscles, neurons, cartilage, and bone under chemically defined culture conditions. After in vivo transplantation of these cells into immunocompromised mice, they showed dense engraftment in various tissues. The relative ease of recovery and the expression profiles of various markers justify further exploration of IDPSC for clinical therapy. Copyright 2007 S. Karger AG, Basel.

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05/16/2008 - Human dental pulp stem cells--isolation and long term cultivation.

Suchánek J, Soukup T, Ivancaková R, Karbanová J, Hubková V, Pytlík R, Kucerová L.

Charles University in Prague, Faculty of Medicine in Hradec Králové and University Hospital Hradec Králové, Department of Dentistry, Czech Republic. suchanekj@lfhk.cuni.cz  Acta Medica (Hradec Kralove). 2007;50(3):195-201.

Human adult mesenchymal stem cells (MSCs) are rare elements living in various organs (e.g. bone marrow, skeletal muscle), with capability to differentiate in various cell types (e.g. chondrocytes, adipocytes and osteoblasts). In the year 2000, Gronthos and co-workers isolated stem cells from the human dental pulp (DPSCs). Later on, stem cells from exfoliated tooth were also obtained. The aims of our study were to establish protocol of DPSCs isolation and to cultivate DPSCs either from adult or exfoliated tooth, and to compare these cells with mesenchymal progenitor cell (MPCs) cultures. MPCs were isolated from the human bone marrow of proximal femur. DPSCs were isolated from deciduous and permanent teeth. Both cell types were cultivated under the same conditions in the media with 2% of FCS supplemented with PDGF and EGF growth factors. We have cultivated undifferentiated DPSCs for long time, over 60 population doublings in cultivation media designed for bone marrow MPCs. After reaching Hayflick's limit, they still have normal karyotype. Initial doubling time of our cultures was from 12 to 50 hours for first 40 population doublings, after reaching 50 population doublings, doubling time had increased to 60-90 hours. Regression analysis of uncumulated population doublings proved tight dependence of population doublings on passage number and slow decrease of proliferation potential. In comparison with bone marrow MPCs, DPSCs share similar biological characteristics and stem cell properties. The results of our experiments proved that the DPSCs and MPCs are highly proliferative, clonogenic cells that can be expanded beyond Hayflick's limit and remain cytogenetically stable. Moreover we have probably isolated two different populations of DPSCs. These DPSCs lines differed one from another in morphology. Because of their high proliferative and differentiation potential, DPSCs can become more attractive, easily accessible source of adult stem cells for therapeutic purposes.
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05/15/2008 - Multilineage differentiation potential of stem cells derived from human dental pulp after cryopreservation
Tissue Eng. 2006 Oct;12(10):2813-23

Zhang W, Walboomers XF, Shi S, Fan M, Jansen JA.

Radboud University Nijmegen Medical Centre, Periodontology & Biomaterials, Nijmegen, The Netherlands.

The current study aimed to prove that human dental pulp stem cells (hDPSCs) isolated from the pulp of third molars can show multilineage differentiation after cryopreservation. First, hDPSC were isolated via enzymatic procedures, and frozen in liquid nitrogen until use. After defrosting, cells were analyzed for proliferative potential and the expression of the stem cell marker STRO-1. Subsequently, cells were cultured in neurogenic, osteogenic/odontogenic, adipogenic, myogenic, and chondrogenic inductive media, and analyzed on basis of morphology, immunohistochemistry, and reverse transcriptase-polymerase chain reaction (RT-PCR) for specific marker genes. All data were replicated, and the results of the primary cells were compared to similar tests with an additional primary dental pulp stem cell strain, obtained from the National Institutes of Health (NIH). Results showed that our cell population could be maintained for at least 25 passages. The existence of stem/ progenitor cells in both cell strains was proven by the STRO-1 staining. Under the influence of the 5 different media, both cell strains were capable to advance into all 5 differentiation pathways. Still differences between both strains were found. In general, our primary culture performed better in myogenic differentiation, while the externally obtained cells were superior in the odontogenic/osteogenic and chondrogenic differentiation pathways. In conclusion, the pulp tissue of the third molar may serve as a suitable source of multipotent stem cells for future tissue engineering strategies and cell-based therapies, even after cryopreservation.

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04/29/2008 - A new population of human adult dental pulp stem cells: a useful source of living autologous fibrous bone tissue (LAB)
J Bone Miner Res. 2005 Aug;20(8):1394-402. Epub 2005 Mar 28

Laino G, d'Aquino R, Graziano A, Lanza V, Carinci F, Naro F, Pirozzi G, Papaccio G.

Dipartimento di Medicina Sperimentale, Sezione Istologia ed Embriologia, Secondo Ateneo di Napoli, Napoli, Italy.

Stem cells, derived from human adult dental pulp of healthy subjects 30-45 years of age, were cultured, and cells were selected using a FACSorter. A new c-kit+/CD34+/CD45- cell population of stromal bone producing cells (SBP/DPSCs) was selected, expanded, and cultured. These SBP/DPSCs are highly clonogenic and, in culture, differentiate into osteoblast precursors (CD44+/RUNX-2+), still capable of self-renewing, and then in osteoblasts, producing, in vitro, a living autologous fibrous bone (LAB) tissue, which is markedly positive for several bone antibodies. This tissue constitute an ideal source of osteoblasts and mineralized tissue for bone regeneration. In fact, after in vivo transplantation into immunocompromised rats, LAB formed lamellar bone-containing osteocytes. INTRODUCTION: Recently it has been reported that human dental pulp stem cells (DPSCs) are detectable, in humans, only up to the age of 30 years and that they are able to produce in vitro only sporadic calcified nodules and to form, after transplantation in vivo, a mineralized tissue. MATERIALS AND METHODS: Stem cells, derived from human adult dental pulp of healthy subjects 30-45 years of age, were cultured, and cells were selected using a FACSorter. Light microscope, histochemistry, immunofluorescence, and RT-PCR analyses were performed to study both stem and differentiating cells. RESULTS AND CONCLUSIONS: A new c-kit+/CD34+/CD45- cell population of stromal bone producing cells (SBP/DPSCs) has been selected by FACSorting, expanded, and cultured. These SBP/DPSCs are highly clonogenic and, in culture, differentiate into osteoblast precursors (CD44+/RUNX-2+), still capable of self-renewing, and in osteoblasts, producing, in vitro, a living autologous fibrous bone (LAB) tissue. This new-formed tissue is markedly positive for several antibodies for bone, including osteonectin, bone sialoprotein, osteocalcin, fibronectin, collagen III, and bone alkaline phosphatase (BALP). Cells producing LAB can be stored at -80 degrees C for a long period of time and are an extraordinary source of osteoblasts and mineralized fibrous bone tissue. In this study, we also showed that, in aged humans, stem cells can be detected from their pulps. The produced LAB is a fibrous bone tissue resembling the human bone during mineralization, with an external layer formed by osteoblasts markedly positive for osteocalcin. This newly formed tissue constitute an ideal source of osteoblasts and mineralized tissue for bone regeneration. In fact, after in vivo transplantation into immunocompromised rats, LAB formed lamellar bone containing osteocytes.

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04/28/2008 - Multipotent Mesenchymal Stem Cells With Immunosuppressive Activity Can Be Easily Isolated From Dental Pulp

Transplantation. 2005 Sep 27; 80(6):836-42.

Pierdomenico L, Bonsi L, Calvitti M, Rondelli D, Arpinati M, Chirumbolo G, Becchetti E, Marchionni C, Alviano F, Fossati V, Staffolani N, Franchina M, Grossi A, Bagnara GP.

Department of Histology, Embryology, and Applied Biology, University of Bologna, Bologna, Italy.

BACKGROUND: Bone marrow mesenchymal stem cells (MSCs) are currently being investigated in preclinical and clinical settings because of their multipotent differentiative capacity or, alternatively, their immunosuppressive function. The aim of this study was to evaluate dental pulp (DP) as a potential source of MSCs instead of bone marrow (BM). METHODS: Flow cytometric analysis showed that DP-MSCs and BM-MSCs were equally SH2, SH3, SH4, CD29 and CD 166 positive. The in vitro proliferative kinetics of MSCs were measured by 3H-thymidine incorporation uptake. The immunosuppressive function of MSCs was then tested by coculturing PHA-stimulated allogeneic T cells with or without MSCs for 3 days. RESULTS: BM-MSCs could be differentiated in vitro into osteogenic, chondrogenic and adipogenic lineages. DP-MSCs showed osteogenic and adipocytic differentiation, but did not differentiate into chondrocytes. Although DP-MSCs grow rapidly in vitro between day 3 and day 8 of culture and then decrease their proliferation by day 15, BM-MSCs have a stable and continuous proliferation over the same period of time. The addition of DP-MSCs or BM-MSCs resulted in 91 +/- 4% and 75 +/- 3% inhibition of T cell response, respectively, assessed by a 3H-thymidine assay. CONCLUSIONS: Dental pulp is an easily accessible and efficient source of MSCs, with different kinetics and differentiation potentialities from MSCs as isolated from the bone marrow. The rapid proliferative capacity together with the immunoregulatory characteristics of DP-MSCs may prompt future studies aimed at using these cells in the treatment or prevention of T-cell alloreactivity in hematopoietic or solid organ allogeneic transplantation.
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04/27/2008 - In vivo evaluation of human dental pulp stem cells differentiated towards multiple lineages.
Zhang W, Walboomers XF, Van Kuppevelt TH, Daamen WF, Van Damme PA, Bian Z, Jansen JA.

Department of Periodontology and Biomaterials, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands. J Tissue Eng Regen Med. 2008 Mar 14

An increasing number of investigations supports that adult stem cells have the potential to differentiate into matured cell types beyond their origin, a property defined as plasticity. Previously, the plasticity of stem cells derived from dental pulp (DPSC) has been confirmed by culturing cells in lineage-specific media in vitro. In the current study, the in vivo differentiation or maturation potential of DPSC was further analysed, by transplanting human DPSC/collagen scaffold constructs into subcutaneous tissue of immunocompromised mice. Cells received odontogenic, adipogenic or myogenic pre-induction, whereas control samples received no stimulation. Also blank collagen scaffolds were implanted. The results indicated that seeded cells produced tissue within the implanted constructs after 3 weeks of implantation. According to morphological and phenotypical changes, the pre-induced DPSC showed the ability to further differentiate along odontogenic, myogenic and adipogenic pathways in vivo. Moreover, DPSC without pre-treatment were able to spontaneously differentiate along odontogenic and adipogenic directions in vivo. However, only limited mature morphological changes were detected in histology. In summary, stem cells derived from human dental pulp form a suitable source for tissue engineering and cell-mediated therapy, although additional analyses should be considered. Copyright (c) 2008 John Wiley & Sons, Ltd.
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04/27/2008 - Long-term cryopreservation of dental pulp stem cells (SBP-DPSCs) and their differentiated osteoblasts: a cell source for tissue repair

Journal of Cellular Physiology. 2006 Aug; 208(2):319-25.

Papaccio G, Graziano A, d'Aquino R, Graziano MF, Pirozzi G, Menditti D, De Rosa A, Carinci F, Laino G.

Dipartimento di Medicina Sperimentale, Sezione di Istologia ed Embriologia, Secondo Ateneo di Napoli, Napoli, Italy. gianpaolo.papaccio@unina2.it

It is not known whether cells derived from stem cells retain their differentiation and morpho-functional properties after long-term cryopreservation. This information is of importance to evaluate their potential for long-term storage with a view to subsequent use in therapy. Here, we describe the morpho-functional properties of dental pulp stem cells (SBP-DPSCs), and of their differentiated osteoblasts, recovered after long-term cryopreservation. After storage for 2 years, we found that stem cells are still capable of differentiation, and that their differentiated cytotypes proliferate and produce woven bone tissue. In addition, cells still express all their respective surface antigens, confirming cellular integrity. In particular, SBP-DPSCs differentiated into pre-osteoblasts, showing diffuse positivity for ALP, BAP, RUNX-2, and calcein. Recovered osteoblasts expressed bone-specific markers and were easily recognizable ultrastructurally, with no alterations observed at this level. In addition, after in vivo transplantation, woven bone converted into a 3D lamellar bone type. Therefore, dental pulp stem cells and their osteoblast-derived cells can be long-term cryopreserved and may prove to be attractive for clinical applications.
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04/27/2008 - Isolation and characterization of dental pulp stem cells from a supernumerary tooth
J Oral Pathol Med. 2008 Mar 5

Huang AH, Chen YK, Lin LM, Shieh TY, Chan AW.

Grace Dental Clinic, Kaohsiung, Taiwan.

Background: Dental pulp stem cells (DPSCs) were primarily derived from the pulp tissues of primary incisors and permanent third molar teeth, whereas no report to our knowledge has yet been documented on deriving DPSCs from the other tooth types. The aim of this study is to present a novel approach of harvesting stem cells from a supernumerary tooth (a mesiodens). Materials and methods: The pulp tissues from a mesiodens of a 20-year-old healthy male patient and the left lower deciduous canine of a healthy 10-year-old boy (the positive control) were extracted and cultured for DPSCs, which were examined with stem cells (Oct-4, Nanog and Rex-1) and differentiation (Osteonectin and Nestin) markers. Furthermore, DPSCs were directionally differentiated to osteogenic and adipogenic cell lineages. Results: Dental pulp stem cells derived from the mesiodens were capable of differentiating into adipogenic and osteogenic lineages. The mesioden's DPSCs also expressed stem cell and differentiation markers, which suggested their stem cell origin and differentiation capability. All the aforementioned results for the mesiodens were consistent with those of the DPSCs derived from the positive control. Conclusion: We have demonstrated the feasibility of deriving DPSCs from a usually discarded tissue such as a supernumerary tooth.

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04/27/2008 - Human postnatal dental pulp cells co-differentiate into osteoblasts and endotheliocytes: a pivotal synergy leading to adult bone tissue formation.
Cell Death Differ. 2007 Jun;14(6):1162-71. Epub 2007 Mar 9

d'Aquino R, Graziano A, Sampaolesi M, Laino G, Pirozzi G, De Rosa A, Papaccio G.

Dipartimento di Discipline Odontostomatologiche, Ortodontiche e Chirurgiche, Università Secondo Ateneo di Napoli, Napoli, Italy.

Stromal stem cells from human dental pulp (SBP-DPSCs) were used to study osteogenic differentiation in vitro and in vivo. We previously reported that SBP-DPSCs are multipotent stem cells able to differentiate into osteoblasts, which synthesize three-dimensional woven bone tissue chips in vitro. In this study, we followed the temporal expression pattern of specific markers in SBP-DPSCs and found that, when differentiating into osteoblasts, they express, besides osteocalcin, also flk-1 (VEGF-R2). In addition, 30% of them expressed specific antigens for endothelial cells, including CD54, von-Willebrand (domain 1 and 2), CD31 (PECAM-1) and angiotensin-converting enzyme. Interestingly, we found endotheliocytes forming vessel walls, observing that stem cells synergically differentiate into osteoblasts and endotheliocytes, and that flk-1 exerts a pivotal role in coupling osteoblast and endotheliocyte differentiation. When either SBP-DPSCs or bone chips obtained in vitro were transplanted into immunocompromised rats, they generated a tissue structure with an integral blood supply similar to that of human adult bone; in fact, a large number of HLA-1+ vessels were observed either within the bone or surrounding it in a periosteal layer. This study provides direct evidence to suggest that osteogenesis and angiogenesis mediated by human SBP-DPSCs may be regulated by distinct mechanisms, leading to the organization of adult bone tissue after stem cell transplantation.

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04/27/2008 - Comparison between osteoblasts derived from human dental pulp stem cells and osteosarcoma cell lines.
Cell Biol Int. 2008 Mar 4

Palmieri A, Pezzetti F, Graziano A, Riccardo D, Zollino I, Brunelli G, Martinelli M, Arlotti M, Carinci F.

Centre of Molecular Genetics, CARISBO Foundation, Institute of Histology and General Embryology, School of Medicine, University of Bologna, Bologna, Italy.

Stem cells derived from human dental pulp are able to differentiate into osteoblasts and are a potential source of autologous bone. The aim of this study was to compare genes differentially expressed in osteoblastoids from human dental pulp (OHDP) to osteosarcoma cells (OCs). Human dental pulp was extracted and immersed in a digestive solution. Cells were cultured and selected using c-kit, CD34, CD45 and STRO-1 antibodies. In parallel, two OCs (i.e., SAOS2 and TE85) were cultured. RNA was extracted from different populations of cells and cDNA was used for the hybridisation of human 19.2K DNA microarrays. We identified several differences in gene expression between OHDP and OCs. Some down-regulated OHDP genes, such as RUNX1, MAP4K4 and PRDM2, are involved in bone development, cell motility and transcript regulation. Gene expression in OHDP is significantly different from that in OCs, suggesting differences in cell function and activity between these cells.

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04/26/2008 - Human CD34+ stem cells produce bone nodules in vivo
Cell Prolif. 2008 Feb;41(1):1-11

Graziano A, d'Aquino R, Laino G, Proto A, Giuliano MT, Pirozzi G, De Rosa A, Di Napoli D, Papaccio G.

Dipartimento di Medicina Sperimentale, Sezione Istologia ed Embriologia, TESLab, Secondo Ateneo di Napoli, Napoli, Italy.

OBJECTIVES: The aim of this study was to select and provide enough stem cells for quick transplantation in bone engineering procedures, avoiding any in vitro expansion step. MATERIALS AND METHODS: Dental germ pulp, collected from 25 healthy subjects aged 13-20 years, were subjected to magnetic-activated cell sorting to select a CD34(+) stem cell population capable of differentiating into pre-osteoblasts. These cells were allowed to adhere to an absorbable polylactic-coglycolic acid scaffold for 30 min, without any prior expansion, and the CD34(+) cell-colonized scaffolds were then transplanted into immunocompromised rats, subcutaneously. RESULTS: After 60 days, analysis of recovered transplants revealed that they were formed of nodules of bone, of the same dimensions as the original scaffold. Bone-specific proteins were detected by immunofluorescence, within the nodules, and X-ray diffraction patterns revealed characteristic features of bone. In addition, presence of platelet endothelial cell adhesion molecule and von Willebrand factor immunoreactivity were suggestive of neo-angiogenesis and neovasculogenesis taking place within nodules. Importantly, these vessels were HLA-1(+) and, thus, clearly human in origin. CONCLUSIONS: This study indicates that CD34(+) cells obtained from dental pulp can be used for engineering bone, without the need for prior culture expanding procedures. Using autologous stem cells, this schedule could be used to provide the basis for bone regenerative surgery, with limited sacrifice of tissue, low morbidity at the collection site, and significant reduction in time needed for clinical recovery.

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04/26/2008 - The characteristics of cultured dental pulp cells and the localization of dental pulp stem cells

Oral and Maxillofacial Department, Qilu Hospital of Shangdong University, Jinan 250012, Shandong province, China. lshabccba@sdu.edu.cn

PURPOSE: This study was aimed to investigate the localization of dental pulp stem cells (DPSCs) by comparing the characteristics of cultured dental pulp cells in coronal and root pulp. METHODS: Human dental coronal and root pulp cells were cultured in tissue-explant method, the cell culture successfulness, attachment efficiency, cell viality, morphology, proliferation pattern, and the mineralization ability were observed, the localization of DPSCs was investigated in the functional respect of DPSCs. RESULTS: The human dental root pulp cells have more culture successfulness,more attachment efficiency,more cell viality, more primary characteristics, and stronger induced mineralization ability than that of coronal pulp cells. Root and coronal pulp cells showed same proliferation patterns. CONCLUSIONS: DPSCs may exist in both dental root and coronal pulp, and the density of DPSCs in the root pulp may be higher than the coronal pulp.

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04/26/2008 - Characterization of the apical papilla and its residing stem cells from human immature permanent teeth: a pilot study.

Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, Los Angeles, California, USA.

Mesenchymal stem cells (MSCs) have been isolated from the pulp tissue of permanent teeth (dental pulp stem cells or DPSCs) and deciduous teeth (stem cells from human exfoliated deciduous teeth). We recently discovered another type of MSCs in the apical papilla of human immature permanent teeth termed stem cells from the apical papilla (SCAP). Here, we further characterized the apical papilla tissue and stem cell properties of SCAP using histologic, immunohistochemical, and immunocytofluorescent analyses. We found that the apical papilla is distinctive to the pulp in terms of containing less cellular and vascular components than those in the pulp. Cells in the apical papilla proliferated 2- to 3-fold greater than those in the pulp in organ cultures. Both SCAP and DPSCs were as potent in osteo/dentinogenic differentiation as MSCs from bone marrows, whereas they were weaker in adipogenic potential. The immunophenotype of SCAP is similar to that of DPSCs on the osteo/dentinogenic and growth factor receptor gene profiles. Double-staining experiments showed that STRO-1 coexpressed with dentinogenic markers such as bone sialophosphoprotein, osteocalcin, and growth factors FGFR1 and TGFbetaRI in cultured SCAP. Additionally, SCAP express a wide variety of neurogenic markers such as nestin and neurofilament M upon stimulation with a neurogenic medium. We conclude that SCAP are similar to DPSCs but a distinct source of potent dental stem/progenitor cells. Their implications in root development and apexogenesis are discussed.

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04/26/2008 - The State of the Art in Human Dental Stem Cell Research

Mund Kiefer Gesichtschir. 2007 Sep 6

Morsczeck C, Reichert TE, Völlner F, Gerlach T, Driemel O.

Institut für Humangenetik, Universität Regensburg, Franz-Josef-Strauß-Allee Regensburg, Germany

This review article arranges the current results of stem cell biology for their use in dentistry. There are different types of stem cells, which are applicable for dental treatments. The use of embryonic stem cells, whose possibilities for breeding an artificial tooth were hardly evaluated, is however ethically precarious. On the other side the ethically harmless adult stem cells, which were isolated for example from bone marrow, were little examined for their capability of differentiation into dental tissues. Therefore their forthcoming use in dentistry is rather improbable. However, dental ectomesenchymal stem cells are more promising for dentistry in future. For example dental pulp stem cells (DPSCs) are capable to differentiate into dentin under in vitro conditions. Moreover it is possible to use periodontal ligament (PDL) stem cells and dental follicle precursors for periodontal tissue differentiations in vitro. Recently new populations of stem cells were isolated from the dental pulp and the PDL. These cells distinguish from the initially isolated DPSCs and PDL stem cells in growth and cell differentiation. Therefore stem cell markers are very important for the characterization of dental stem cells. A significant marker for dental stem cells is STRO-1, which is also a marker for bone marrow derived mesenchymal stem cells. Nonetheless dental stem cells are CD45 negative and they express rarely hematopoietic stem cell markers.These research results plead for the participation of dental stem cells in dental practice in future.
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04/26/2008 - Adult Mesenchymal Stem Cells In Dental Research: A New Approach For Tissue Engineering

International Journal Immunopathology & Pharmacology. 2006 Jul-Sep; 19(3):451-60.

Trubiani O, Orsini G, Caputi S, Piatelli A.

Department of Stomatology and Oral Science, Ce.SI. Foundation G. d'Annunzio, Chieti, Italy.

Many adult tissues contain a population of stem cells that have the ability to regenerate after trauma, disease or aging. Recently, there has been great interest in mesenchymal stem cells and their roles in maintaining the physiological structure of tissues. The studies on stem cells are thought to be very important and, in fact, it has been shown that this cell population can be expanded ex vivo to regenerate tissues not only of the mesenchymal lineage, such as intervertebral disc cartilage, bone and tooth-associated tissues, but also other types of tissues. Several studies have focused on the identification of odontogenic progenitors from oral tissues, and it has been shown that the mesenchymal stem cells obtained from periodontal ligament and dental pulp could have similar morphological and phenotypical features of the bone marrow mesenchymal cells. In fact a population of homogeneous human mesenchymal stem cells derived from periodontal ligament and dental pulp, and proliferating in culture with a well-spread morphology, can be recovered and characterized. Since these cells are considered as candidates for regenerative medicine, the knowledge of the cell differentiation mechanisms is imperative for the development of predictable techniques in implant dentistry, oral surgery and maxillo-facial reconstruction. Thus, future research efforts might be focused on the potential use of this cell population in tissue engineering. Further studies will be carried out to elucidate the molecular mechanisms involved in their maintenance and differentiation in vitro and in vivo.
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