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2009

Dental tissue -- new source for stem cells.
Petrovic V, Stefanovic V.

Scientific World Journal
2009 Oct 14;9:1167-77
[full article]

Abstract: 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.

Mesenchymal stem cells derived from dental tissues vs. those from other sources: their biology and role in regenerative medicine.
Huang GT, Gronthos S, Shi S.

J Dent Res
2009 Sep;88(9):792-806
[full article]

Abstract: 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.

Banking stem cells from human exfoliated deciduous teeth (SHED): saving for the future.
Arora V, Arora P, Munshi AK.

J Clin Pediatr Dent
2009 Summer;33(4):289-94
[full article]

Abstract: 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.

Hypoxia affects the proliferation and migration abilities of dental pulp
J. Quan, Q. Gong, H. Jiang, and J. Ling

IADR Pan Asian Pacific Federation Conference
2009 Sept
[full article]

OBJECTIVES: To investigate the biological effects of hypoxia on the proliferation ability of human dental pulp cells(HDPCs), detect the relative amount of the messenger RNA of hypoxia induced factor-1a(HIF-1a), stromal cell-derived factor-1a(SDF-1a) and CXCR4 in HDPCs under hypoxia condition, and explore the chemotactic effect of exogenous recombinant human SDF-1a(rhSDF-1a) on hypoxic HDPCs.
METHODS: Cultured HDPCs were exposed to normoxia(20%O2)or hypoxia(1% O2) for 6, 12, 18 and 24 hours, then the proliferation of HDPCs was assessed by MTT assay. After being exposed to hypoxia for 6,12,18 and 24 hours, the cell samples were collected and the relative amount of the messenger RNA of HIF-1a, CXCR4 and SDF-1a were assayed by real-time quantitative PCR. The chemotactic effect of 100ng/ml rhSDF-1a on HDPCs either cultured in normoxia or hypoxia for 18 hours was measured by the in vitro chemotaxis assay.
RESULTS: MTT assay showed increased OD value in all hypoxic groups during the 24hs' cultivation (P<0.05). Comparing with the normoxic group, Real-time quantitative PCR showed that the expression level of CXCR4 increased in the 18h's groups (P<0.05), while the expression level of SDF-1a decreased in the 6h's, 18h's and 24h's groups (P<0.05). The chemotaxis assay showed that hypoxia enhanced the migration ability of HDPCs, and 100ng/ml rhSDF-1a migrated more hypoxic HDPCs than normoxic HDPCs (P<0.05).
CONCLUSIONS: During the 24hs' cultivation in hypoxic environment, HDPCs proliferated at a faster rate. Comparing with the normoxic group, the expression level of CXCR4 increased and the expression level of SDF-1a decreased. Furthermore, hypoxia enhanced the migration ability of HDPCs and recombinant human SDF-1a could migrate hypoxic HDPCs efficiently. These results suggest that hypoxia may recruit HDPCs to sites of injury through activating the SDF-1-CXCR4 pathway.

Hepatic lineage differentiation of milk and third molar pulp cells
N. Ishkitiew, T. Nakahara, T. Sato, V. Mitev, and K. Yaegaki

IADR/AADR/CADR 87th General Session Conference
2009 April
[full article]

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.

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

Cytotherapy
2009;11(5):606-17
[full article]

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 15-20mL normal saline. The mixture of dental pulp was collected by centrifugation and cultured in a 25-cm(2) tissue culture flask with 4-5mL 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.

Simultaneous PKC and cAMP activation induces differentiation of human dental pulp stem cells into functionally active neurons.
Király M, Porcsalmy B, Pataki A, Kádár K, Jelitai M, Molnár B, Hermann P, Gera I, Grimm WD, Ganss B, Zsembery A, Varga G.

Neurochem Int
2009 Sep;55(5):323-32
[full article]

Abstract: 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.

Optimized cryopreservation method for human dental pulp-derived stem cells and their tissues of origin for banking and clinical use.
Király M, Porcsalmy B, Pataki A, Kádár K, Jelitai M, Molnár B, Hermann P, Gera I, Grimm WD, Ganss B, Zsembery A, Varga G.

Cryobiology
2009 Oct;59(2):150-7
[full article]

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 120h 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 Me(2)SO 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 2x10(6) cells/mL. It was further established that DPSC can be stored at -85 degrees C or -196 degrees 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.

Identification of novel epithelial stem cell-like cells in human deciduous dental pulp.
Nam H, Lee G.

Biochem Biophys Res Commun
2009 Aug 14;386(1):135-9
[full article]

Abstract: 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.

Hypoxia-amplified proliferation of human dental pulp cells.
Sakdee JB, White RR, Pagonis TC, Hauschka PV.

J Endod
2009 Jun;35(6):818-23
[full article]

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.

Dental pulp stem cells and their characterization.
Suchanek J, Soukup T, Visek B, Ivancakova R, Kucerova L, Mokry J.

Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub
2009 Mar;153(1):31-5
[full article]

AIMS: Our aims were to isolate dental pulp stem cells, to cultivate them in various media and to investigate their basic biological properties and phenotype.
METHODS: 16 lines of dental pulp stem cells (DPSCs) were isolated from an impacted third molar. After enzymatic dissociation of dental pulp, DPSCs were cultivated in modified cultivation media for mesenchymal adult progenitor cells containing 2 % or 10 % fetal calf serum (FCS), or in modified 2 % FCS cultivation media supplemented with ITS. Cell viability and other biological properties were examined periodically using a Vi-Cell analyzer and Z2-Counter. DNA analysis and phenotyping were done using flow cytometry.
RESULTS: We were able to cultivate DPSCs in all tested cultivation media over 40 population doublings. Our results showed that DPSCs cultivated in medium supplemented with ITS had shorter average population doubling time (24.5, 15.55-35.12 hours) than DPSCs cultivated in 2 % FCS (55.43, 21.57-187.14 hours) or 10 % FCS (42.56, 11.86 - 101.3 hours). Cell diameter was not affected and varied from 15 to 16 microm. DPSCs viability in the 9(th) passage was over 90 %. Our phenotypical analysis was highly positivity for CD29, CD44, CD90 and HLA I, and negative for CD34, CD45, CD71, HLA II. DPSC lines cultivated in all media showed no signs of degeneration or spontaneous differentiation during the expansion process.
CONCLUSIONS: We showed that ITS supplement in the cultivation media greatly increased the proliferative activity of DPSCs. Other DPSC biological properties and phenotype were not affected.

Differentiation and regenerative capacities of human odontoma-derived mesenchymal cells.
Song JS, Stefanik D, Damek-Poprawa M, Alawi F, Akintoye SO.

Differentiation
2009 Jan;77(1):29-37
[full article]

Abstract: Regenerating human tooth ex vivo and biological repair of dental caries are hampered by non-viable odontogenic stem cells that can regenerate different tooth components. Odontoma is a developmental dental anomaly that may contain putative post-natal stem cells with the ability to differentiate and regenerate in vivo new dental structures that may include enamel, dentin, cementum and pulp tissues. We evaluated odontoma tissues from 14 patients and further isolated and characterized human odontoma-derived mesenchymal cells (HODCs) with neural stem cell and hard tissue regenerative properties from a group of complex odontoma tissues from 1 of 14 patients. Complex odontoma was more common (9 of 14) than compound type and females (9 of 14) were more affected than males in our set of patients. HODCs were highly proliferative like dental pulp stem cells (DPSCs) but demonstrated stronger neural immunophenotype than both DPSCs and mandible bone marrow stromal cells (BMSCs) by expressing higher levels of nestin, Sox 2 and betaIII-tubulin. When transplanted with hydroxyapatite/tricalcium phosphate into immunocompromised mice, HODCs differentiated and regenerated calcified hard tissues in vivo that were morphologically and quantitatively comparable to those generated by DPSCs and BMSCs. When transplanted with polycaprolactone (biodegradable carrier), HODCs differentiated to form new predentin on the surface of a dentin platform. Newly formed predentin contained numerous distinct dentinal tubules and an apparent dentin-pulp arrangement. HODCs represent unique odontogenic progenitors that readily commit to formation of dental hard tissues.

Evaluation of pluripotency in human dental pulp cells.
Koyama N, Okubo Y, Nakao K, Bessho K.

J Oral Maxillofac Surg
2009 Mar;67(3):501-6
[full article]

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.

Dental pulp stem cells: what, where, how?
Sloan AJ, Waddington RJ.

Int J Paediatr Dent
2009 Jan;19(1):61-70
[full article]

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.

 

Cardiac differentiation is driven by NKX2.5 and GATA4 nuclear translocation in tissue-specific mesenchymal stem cells.
Armiñán A, Gandía C, Bartual M, García-Verdugo JM, Lledó E, Mirabet V, Llop M, Barea J, Montero JA, Sepúlveda P.

Stem Cells Dev
2009 Jul-Aug;18(6):907-18
[full article]

Abstract: Myocardial infarction is a major public health problem that causes significant mortality despite recent advances in its prevention and treatment. Therefore, approaches based on adult stem cells represent a promising alternative to conventional therapies for this life-threatening condition. Mesenchymal stem cells (MSCs) are self-renewing pluripotent cells that have been isolated from multiple tissues and differentiate to various cell types. Here we have analyzed the capacity of MSCs from human bone marrow (BMSC), adipose tissue (ATSC), and dental pulp (DPSC) to differentiate to cells with a cardiac phenotype. Differentiation of MSCs was induced by long-term co-culture with neonatal rat cardiomyocytes (CMs). Shortly after the establishment of MSC-CM co-cultures, expression of connexin 43 and the cardiac-specific markers troponin I, beta-myosin heavy chain, atrial natriuretic peptide, and alpha-sarcomeric actinin was detected in BMSCs, ATSCs, and DPSCs. Expression of differentiation markers increased over time in the co-cultures, reaching the highest levels at 4 weeks. Translocation of the transcription factors NKX2.5 and GATA4 to the nucleus was observed in all three cultures of MSCs during the differentiation process; moreover, nuclear localization of NKX2.5 and GATA4 correlated with expression of alpha-sarcomeric actinin. These changes were accompanied by an increase in myofibril organization in the resulting CM-like cells as analyzed by electron microscopy. Thus, our results provide novel information regarding the differentiation of tissue-specific MSCs to cardiomyocytes and support the potential use of MSCs in cell-based cardiac therapies.

 

2008

Tooth-forming potential in embryonic and postnatal tooth bud cells.
Honda MJ, Fong H, Iwatsuki S, Sumita Y, Sarikaya M.

Med Mol Morphol
2008 Dec;41(4):183-92
[full article]

Abstract: Humans are genetically programmed to replace their teeth once during childhood. Therefore, when adult teeth are lost or damaged, they cannot be regenerated or regrown. However, with the advancement of stem cell biology and tissue engineering, regenerating the whole tooth has become a realistic and attractive option to replace a lost or damaged tooth, and therefore has strongly attracted attention in the field of dental research. During the past several years, significant progress has been made in this research endeavor, providing greater understanding of the production of an entire biological tooth by tissue engineering using stem cells. There are several ways to reproduce an entire biological tooth. Approaches are categorized according to the cell sources that have the potential to produce teeth. One source is the embryonic tooth bud, and the other is the postnatal tooth bud. The results from embryonic and postnatal tooth buds differ considerably. In particular, the potential to regulate the shape of the tooth crown from embryonic tooth bud is higher than from postnatal tooth bud. This article describes the achievements to date in production of biological teeth, mostly from our laboratory. In particular, we describe the potential to produce teeth from embryonic and postnatal tooth buds.

Regenerating dentistry: the new realm of stem cells.
Murray P, Pocock N.

Todays FDA
2008 Oct;20(10):35-6
[full article]

Abstract: not available

Whole-tooth regeneration: it takes a village of scientists, clinicians, and patients.
Snead ML.

J Dent Educ
2008 Aug;72(8):903-11
[full article]

Abstract: A team of senior scientists was formed in 2006 to create a blueprint for the regeneration of whole human teeth along with all of the supporting structure of the dentition. The team included experts from diverse fields, each with a reputation for stellar accomplishment. Participants attacked the scientific issues of tooth regeneration but, more importantly, each agreed to work collaboratively with experts from other disciplines to form a learning organization. A commitment to learn from one another produced a unique interdisciplinary and multidisciplinary team. Inspired by the Kennedy space program to send a man to the moon, with its myriad of problems and solutions that no one discipline could solve, this tooth regeneration team devised an ambitious plan that sought to use stem cell biology, engineering, and computational biology to replicate the developmental program for odontogenesis. In this manner, team members envisioned a solution that consisted of known or knowable fundamentals. They proposed a laboratory-grown tooth rudiment that would be capable of executing the complete program for odontogenesis when transplanted to a suitable host, recreating all of the dental tissues, periodontal ligament, cementum, and alveolar bone associated with the canonical tooth. This plan was designed to bring regenerative medicine fully into the dental surgery suite, although a lack of funding has so far prevented the plan from being carried out.

Self-assembling peptide amphiphile nanofibers as a scaffold for dental stem cells.
Galler KM, Cavender A, Yuwono V, Dong H, Shi S, Schmalz G, Hartgerink JD, D'Souza RN.

Tissue Eng Part A
2008 Dec;14(12):2051-8
[full article]

Abstract: Dental caries remains one of the most prevalent infectious diseases in the world. So far, available treatment methods rely on the replacement of decayed soft and mineralized tissue with inert biomaterials alone. As an approach to develop novel regenerative strategies and engineer dental tissues, two dental stem cell lines were combined with peptide-amphiphile (PA) hydrogel scaffolds. PAs self-assemble into three-dimensional networks of nanofibers, and living cells can be encapsulated. Cell-matrix interactions were tailored by incorporation of the cell adhesion sequence RGD and an enzyme-cleavable site. SHED (stem cells from human exfoliated deciduous teeth) and DPSC (dental pulp stem cells) were cultured in PA hydrogels for 4 weeks using different osteogenic supplements. Both cell lines proliferate and differentiate within the hydrogels. Histologic analysis shows degradation of the gels and extracellular matrix production. However, distinct differences between the two cell lines can be observed. SHED show a spindle-shaped morphology, high proliferation rates, and collagen production, resulting in soft tissue formation. In contrast, DPSC reduce proliferation, but exhibit an osteoblast-like phenotype, express osteoblast marker genes, and deposit mineral. Since the hydrogels are easy to handle and can be introduced into small defects, this novel system might be suitable for engineering both soft and mineralized matrices for dental tissue regeneration.

Dental pulp tissue engineering with stem cells from exfoliated deciduous teeth.
Cordeiro MM, Dong Z, Kaneko T, Zhang Z, Miyazawa M, Shi S, Smith AJ, Nör JE.

J Endod
2008 Aug;34(8):962-9
[full article]

Abstract: Stem cells from human exfoliated deciduous teeth (SHED) have been isolated and characterized as multipotent cells. However, it is not known whether SHED can generate a dental pulp-like tissue in vivo. The purpose of this study was to evaluate morphologic characteristics of the tissue formed when SHED seeded in biodegradable scaffolds prepared within human tooth slices are transplanted into immunodeficient mice. We observed that the resulting tissue presented architecture and cellularity that closely resemble those of a physiologic dental pulp. Ultrastructural analysis with transmission electron microscopy and immunohistochemistry for dentin sialoprotein suggested that SHED differentiated into odontoblast-like cells in vivo. Notably, SHED also differentiated into endothelial-like cells, as demonstrated by B-galactosidase staining of cells lining the walls of blood-containing vessels in tissues engineered with SHED stably transduced with LacZ. This work suggests that exfoliated deciduous teeth constitute a viable source of stem cells for dental pulp tissue engineering.

Human periodontal ligament: a niche of neural crest stem cells.
Coura GS, Garcez RC, de Aguiar CB, Alvarez-Silva M, Magini RS, Trentin AG.

J Periodontal Res
2008 Oct;43(5):531-6
[full article]

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.

Gene expression of nestin, collagen type I and type III in human dental follicle cells after cultivation in serum-free medium.
Morsczeck C, Ernst W, Florian C, Reichert TE, Proff P, Bauer R, Müller-Richter U, Driemel O.

Oral Maxillofac Surg
2008 Jul;12(2):89-92
[full article]

BACKGROUND: Undifferentiated human dental cells and especially human dental follicle cells are interesting for potential dental treatments. These somatic stem cells are cultured usually in cell culture medium containing bovine serum. In the age of bovine spongiform encephalopathy (BSE), a serum-free cell culture system for dental follicle cells are recommended, if these cells will be applied in dentistry.
PURPOSE: However, less is known about the cultivation of dental follicle cells in serum-replacement medium. In this study, we cultivated dental follicle cells in serum-free cell culture medium, which is normally applied for neuronal stem/progenitor cells.
MATERIALS AND METHODS: Dental follicle cells were cultivated in both serum-free and serum-containing cell culture media, and gene expression profiles were recorded for connective tissue markers collagen type I and type III and for the human dental follicle cell marker nestin.
RESULTS: It is interesting to note that the gene expressions of collagens and nestin were similar after applying both cell culture conditions.
CONCLUSION: Although the gene expression of dental follicle cell markers was unchanged, a more appropriate serum-free cell culture medium is recommended for cell proliferation of dental follicle cells.

Inflammatory and immunological aspects of dental pulp repair.
Goldberg M, Farges JC, Lacerda-Pinheiro S, Six N, Jegat N, Decup F, Septier D, Carrouel F, Durand S, Chaussain-Miller C, Denbesten P, Veis A, Poliard A.

Pharmacol Res
2008 Aug;58(2):137-47
[full article]

Abstract: The repair of dental pulp by direct capping with calcium hydroxide or by implantation of bioactive extracellular matrix (ECM) molecules implies a cascade of four steps: a moderate inflammation, the commitment of adult reserve stem cells, their proliferation and terminal differentiation. The link between the initial inflammation and cell commitment is not yet well established but appears as a potential key factor in the reparative process. Either the release of cytokines due to inflammatory events activates resident stem (progenitor) cells, or inflammatory cells or pulp fibroblasts undergo a phenotypic conversion into osteoblast/odontoblast-like progenitors implicated in reparative dentin formation. Activation of antigen-presenting dendritic cells by mild inflammatory processes may also promote osteoblast/odontoblast-like differentiation and expression of ECM molecules implicated in mineralization. Recognition of bacteria by specific odontoblast and fibroblast membrane receptors triggers an inflammatory and immune response within the pulp tissue that would also modulate the repair process.

Early transplantation of human immature dental pulp stem cells from baby teeth to golden retriever muscular dystrophy (GRMD) dogs: Local or systemic?
Kerkis I, Ambrosio CE, Kerkis A, Martins DS, Zucconi E, Fonseca SA, Cabral RM, Maranduba CM, Gaiad TP, Morini AC, Vieira NM, Brolio MP, Sant'Anna OA, Miglino MA, Zatz M.

J Transl Med
2008 Jul 3;6:35
[full article]

BACKGROUND: The golden retriever muscular dystrophy (GRMD) dogs represent the best available animal model for therapeutic trials aiming at the future treatment of human Duchenne muscular dystrophy (DMD). We have obtained a rare litter of six GRMD dogs (3 males and 3 females) born from an affected male and a carrier female which were submitted to a therapeutic trial with adult human stem cells to investigate their capacity to engraft into dogs muscles by local as compared to systemic injection without any immunosuppression.
METHODS: Human Immature Dental Pulp Stem Cells (hIDPSC) were transplanted into 4 littermate dogs aged 28 to 40 days by either arterial or muscular injections. Two non-injected dogs were kept as controls. Clinical translation effects were analyzed since immune reactions by blood exams and physical scores capacity of each dog. Samples from biopsies were checked by immunohistochemistry (dystrophin markers) and FISH for human probes.
RESULTS AND DISCUSSION: We analyzed the cells' ability in respect to migrate, engraftment, and myogenic potential, and the expression of human dystrophin in affected muscles. Additionally, the efficiency of single and consecutive early transplantation was compared. Chimeric muscle fibers were detected by immunofluorescence and fluorescent in situ hybridisation (FISH) using human antibodies and X and Y DNA probes. No signs of immune rejection were observed and these results suggested that hIDPSC cell transplantation may be done without immunosuppression. We showed that hIDPSC presented significant engraftment in GRMD dog muscles, although human dystrophin expression was modest and limited to several muscle fibers. Better clinical condition was also observed in the dog, which received monthly arterial injections and is still clinically stable at 25 months of age.
CONCLUSION: Our data suggested that systemic multiple deliveries seemed more effective than local injections. These findings open important avenues for further researches.

A novel stem cell source for vasculogenesis in ischemia: subfraction of side population cells from dental pulp.
Iohara K, Zheng L, Wake H, Ito M, Nabekura J, Wakita H, Nakamura H, Into T, Matsushita K, Nakashima M.

Stem Cells
2008 Sep;26(9):2408-18
[full article]

Abstract: 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 vascular endothelial growth factor-2 (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 multilineage differentiation potential including vasculogenic potential. In models of mouse hind limb 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 antiapoptotic activity on human umbilical vein endothelial cells. 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.

Comparison between genetic portraits of osteoblasts derived from primary cultures and osteoblasts obtained from human pulpar stem cells.
Carinci F, Papaccio G, Laino G, Palmieri A, Brunelli G, D'Aquino R, Graziano A, Lanza V, Scapoli L, Martinelli M, Pezzetti F.

J Craniofac Surg
2008 May;19(3):616-25; discussion 626-7
[full article]

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.

Adult human dental pulp stem cells differentiate toward functionally active neurons under appropriate environmental cues.
Arthur A, Rychkov G, Shi S, Koblar SA, Gronthos S.

Stem Cells
2008 Jul;26(7):1787-95
[full article]

Abstract: Human adult dental pulp stem cells (DPSCs) 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 DPSCs derived from adult human third molar teeth differentiate into cell types reminiscent of CNC embryonic ontology. We hypothesized that DPSCs exposed to the appropriate environmental cues would differentiate into functionally active neurons. The data demonstrated that ex vivo-expanded human adult DPSCs responded to neuronal inductive conditions both in vitro and in vivo. Human adult DPSCs, but not human foreskin fibroblasts (HFFs), acquired a neuronal morphology, and expressed neuronal-specific markers at both the gene and protein levels. Culture-expanded DPSCs 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 DPSCs and HFFs to endogenous neuronal environmental cues was determined in vivo using an avian xenotransplantation assay. DPSCs expressed neuronal markers and acquired a neuronal morphology following transplantation into the mesencephalon of embryonic day-2 chicken embryo, whereas HFFs maintained a thin spindle fibroblastic morphology. We propose that adult human DPSCs provide a readily accessible source of exogenous stem/precursor cells that have the potential for use in cell-therapeutic paradigms to treat neurological disease.

The hidden treasure in apical papilla: the potential role in pulp/dentin regeneration and bioroot engineering.
Huang GT, Sonoyama W, Liu Y, Liu H, Wang S, Shi S.

J Endod
2008 Jun;34(6):645-51
[full article]

Abstract: Some clinical case reports have shown that immature permanent teeth with periradicular periodontitis or abscess can undergo apexogenesis after conservative endodontic treatment. A call for a paradigm shift and new protocol for the clinical management of these cases has been brought to attention. Concomitantly, a new population of mesenchymal stem cells residing in the apical papilla of permanent immature teeth recently has been discovered and was termed stem cells from the apical papilla (SCAP). These stem cells appear to be the source of odontoblasts that are responsible for the formation of root dentin. Conservation of these stem cells when treating immature teeth may allow continuous formation of the root to completion. This article reviews current findings on the isolation and characterization of these stem cells. The potential role of these stem cells in the following respects will be discussed: (1) their contribution in continued root maturation in endodontically treated immature teeth with periradicular periodontitis or abscess and (2) their potential utilization for pulp/dentin regeneration and bioroot engineering.

Stem cells and the future of dental care.
Mao JJ.

N Y State Dent J
2008 Mar;74(2):20-4
[full article]

Abstract: What are stem cells? As dentists, why should we be concerned with stem cells? How would stem cells change dental practice? Is it possible to grow a tooth or TMJ with stem cells? This article summarizes the latest stem cell research and development for dental, oral and craniofacial applications. Stem cell research and development will, over time, transform dental practice in a magnitude far greater than did amalgam or dental implants. Metallic alloys, composites and even titanium implants are not permanent solutions. In contrast, stem cell technology will generate native tissue analogs that are compatible with the patient's own.

Postnatal stem/progenitor cells derived from the dental pulp of adult chimpanzee.
Cheng PH, Snyder B, Fillos D, Ibegbu CC, Huang AH, Chan AW.

BMC Cell Biol
2008 Apr 22;9:20
[full article]

BACKGROUND: Chimpanzee dental pulp stem/stromal cells (ChDPSCs) are very similar to human bone marrow derived mesenchymal stem/stromal cells (hBMSCs) as demonstrated by the expression pattern of cell surface markers and their multipotent differentiation capability.
RESULTS: ChDPSCs were isolated from an incisor and a canine of a forty-seven year old female chimpanzee. A homogenous population of ChDPSCs was established in early culture at a high proliferation rate and verified by the expression pattern of thirteen cell surface markers. The ChDPSCs are multipotent and were capable of differentiating into osteogenic, adipogenic and chondrogenic lineages under appropriate in vitro culture conditions. ChDPSCs also express stem cell (Sox-2, Nanog, Rex-1, Oct-4) and osteogenic (Osteonectin, osteocalcin, osteopontin) markers, which is comparable to reported results of rhesus monkey BMSCs (rBMSCs), hBMSCs and hDPSCs. Although ChDPSCs vigorously proliferated during the initial phase and gradually decreased in subsequent passages, the telomere length indicated that telomerase activity was not significantly reduced.
CONCLUSION: These results demonstrate that ChDPSCs can be efficiently isolated from post-mortem teeth of adult chimpanzees and are multipotent. Due to the almost identical genome composition of humans and chimpanzees, there is an emergent need for defining the new role of chimpanzee modeling in comparative medicine. Teeth are easy to recover at necropsy and easy to preserve prior to the retrieval of dental pulp for stem/stromal cells isolation. Therefore, the establishment of ChDPSCs would preserve and maximize the applications of such a unique and invaluable animal model, and could advance the understanding of cellular functions and differentiation control of adult stem cells in higher primates.

A paradigm shift in endodontic management of immature teeth: conservation of stem cells for regeneration.
Huang GT.

J Dent
2008 Jun;36(6):379-86
[full article]

OBJECTIVE: This article will review the new concept of regenerative endodontics in the management of immature permanent teeth. The potential role of stem cells to regenerate immature permanent teeth after conservative treatment will be discussed.
DATA AND SOURCES: Two sets of data source are focused in this review: (i) the characterization of various dental stem cells discovered since 2000 and (ii) recent clinical case reports showing that after conservative treatment, severely infected immature teeth with periradicular periodontitis and abscess can undergo healing and apexogenesis or maturogenesis.
RESULTS: A new protocol of treating endodontically involved immature permanent teeth based on published articles to date is summarized in the review. The key procedures of the protocol are (1) minimal or no instrumentation of the canal while relying on a gentle but thorough irrigation of the canal system, (2) the disinfection is augmented with intra-canal medication of a triple-antibiotic paste between appointments, and (3) the treated tooth is sealed with mineral trioxide aggregate (MTA) and glass ionomer/resin cement at the completion of the treatment. Periodical follow-ups will take place to observe any continued maturation of the root.
CONCLUSION: While more clinical research is needed, regenerative endodontics promotes a paradigm shift in treating endodontically involved immature permanent teeth from performing apexification procedures to conserving any dental stem cells that might remain in the disinfected viable tissues to allow tissue regeneration and repair to achieve apexogenesis/maturogenesis.

Human dental pulp stem cells differentiate into neural crest-derived melanocytes and have label-retaining and sphere-forming abilities.
Stevens A, Zuliani T, Olejnik C, LeRoy H, Obriot H, Kerr-Conte J, Formstecher P, Bailliez Y, Polakowska RR.

Stem Cells Dev
2008 Dec;17(6):1175-84
[full article]

Abstract: 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, and 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 may be multipotent neural crest stem cells.

An ultrastructural investigation of tissue-engineered pulp constructs implanted within endodontically treated teeth.
Gotlieb EL, Murray PE, Namerow KN, Kuttler S, Garcia-Godoy F.

J Am Dent Assoc
2008 Apr;139(4):457-65
[full article]

BACKGROUND: The authors conducted an ultrastructural scanning electron microscopic (SEM) investigation of tissue-engineered pulp constructs implanted within endodontically treated teeth.
METHODS: Stem cells from human exfoliated deciduous teeth were seeded on a synthetic open-cell D,D-L,L-polylactic acid scaffold with or without the addition of bone morphogenic protein-2 and transforming growth factor beta1 to create pulp tissue constructs. The pulp constructs were implanted into 105 extracted human premolar teeth with a single root canal that had been cleaned and shaped by using rotary instrumentation in a crown-down manner to ISO size no. 35.
RESULTS: An ultrastructural examination of the SEM micrographs at x2,000 magnification revealed cell adherence within all of the pulp constructs, with little difference between the scaffold types or with the addition of growth factors.
CONCLUSIONS: These results support the proof-of-concept that it is possible to implant tissue-engineered pulp constructs into teeth after cleaning and shaping.
CLINICAL IMPLICATIONS: Future regenerative endodontic treatment may involve the cleaning and shaping of root canals followed by the implantation of vital dental pulp tissue constructs created in the laboratory.

Defining properties of neural crest-derived progenitor cells from the apex of human developing tooth.
Degistirici O, Jaquiery C, Schönebeck B, Siemonsmeier J, Götz W, Martin I, Thie M.

Tissue Eng Part A
2008 Feb;14(2):317-30
[full article]

Abstract: 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.

Isolation and characterization of dental pulp stem cells from a supernumerary tooth.
Huang AH, Chen YK, Lin LM, Shieh TY, Chan AW.

J Oral Pathol Med
2008 Oct;37(9):571-4
[full article]

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.

Dental pulp stem cells: a promising tool for bone regeneration.
Graziano A, d'Aquino R, Laino G, Papaccio G.

Stem Cell Rev
2008 Spring;4(1):21-6
[full article]

Abstract: Human tissues are different in term of regenerative properties. Stem cells are a promising tool for tissue regeneration, thanks to their particular characteristics of proliferation, differentiation and plasticity. Several "loci" or "niches" within the adult human body are colonized by a significant number of stem cells. However, access to these potential collection sites often is a limiting point. The interaction with biomaterials is a further point that needs to be considered for the therapeutic use of stem cells. Dental pulp stem cells (DPSCs) have been demonstrated to answer all of these issues: access to the collection site of these cells is easy and produces very low morbidity; extraction of stem cells from pulp tissue is highly efficiency; they have an extensive differentiation ability; and the demonstrated interactivity with biomaterials makes them ideal for tissue reconstruction. SBP-DPSCs are a multipotent stem cell subpopulation of DPSCs which are able to differentiate into osteoblasts, synthesizing 3D woven bone tissue chips in vitro and that are capable to synergically differentiate into osteoblasts and endotheliocytes. Several studied have been performed on DPSCs and they mainly found that these cells are multipotent stromal cells that can be safety cryopreserved, used with several scaffolds, that can extensively proliferate, have a long lifespan and build in vivo an adult bone with Havers channels and an appropriate vascularization. A definitive proof of their ability to produce dentin has not been yet done. Interestingly, they seem to possess immunoprivileges as they can be grafted into allogenic tissues and seem to exert anti-inflammatory abilities, like many other mesenchymal stem cells. The easy management of dental pulp stem cells make them feasible for use in clinical trials on human patients.

Regenerative potential of human periodontal ligament derived stem cells on three-dimensional biomaterials: a morphological report.
Trubiani O, Orsini G, Zini N, Di Iorio D, Piccirilli M, Piattelli A, Caputi S.

J Biomed Mater Res A
2008 Dec 15;87(4):986-93
[full article]

Abstract: Recent studies have shown that mesenchymal stem cells obtained from periodontal ligament (PDL-MSCs) are multipotent cells that have similar features of the bone marrow and dental pulp MSCs and are capable of proliferating and producing different types of tissue such as bone and tooth associated-tissues. Human PDL-MSCs expanded ex vivo were induced to osteogenesis, seeded in three-dimensional biocompatible scaffolds (fibrin sponge, bovine-derived substitutes) and examined using light, scanning and transmission electron microscopy. Morphological observations showed extensive growth of cellular biomass partially covering the scaffolds after 4 weeks of incubation in mineralization medium. These findings indicate that periodontal ligament can be an easily and efficient autologous source of stem cells with a high expansion capacity and ability to differentiate in osteogenic cells that can colonize and grow connected to bio-compatible scaffold. It can be suggested that the use of PDL-MSCs for generating graft biomaterials is advantageous for bone tissue engineering in regenerative dentistry. 2008 Wiley Periodicals, Inc.

Characterisation of human dental stem cells and buccal mucosa fibroblasts.
Lindroos B, Mäenpää K, Ylikomi T, Oja H, Suuronen R, Miettinen S.

Biochem Biophys Res Commun
2008 Apr 4;368(2):329-35
[full article]

Abstract: parallel to those of other mesenchymal stem cell sources, yet distinct from the buccal mucosa fibroblasts. Our data support evidence towards clinical applicability of dental stem cells in hard tissue regeneration.

Somatic stem cells for regenerative dentistry.
Morsczeck C, Schmalz G, Reichert TE, Völlner F, Galler K, Driemel O.

Clin Oral Investig
2008 Jun;12(2):113-8
[full article]

Abstract: 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.

Human dental pulp stem cells improve left ventricular function, induce angiogenesis, and reduce infarct size in rats with acute myocardial infarction.
Gandia C, Armiñan A, García-Verdugo JM, Lledó E, Ruiz A, Miñana MD, Sanchez-Torrijos J, Payá R, Mirabet V, Carbonell-Uberos F, Llop M, Montero JA, Sepúlveda P.

Stem Cells
2008 Mar;26(3):638-45
[full article]

Abstract: Human dental pulp contains precursor cells termed dental pulp stem cells (DPSC) that show self-renewal and multilineage differentiation and also secrete multiple proangiogenic and antiapoptotic factors. To examine whether these cells could have therapeutic potential in the repair of myocardial infarction (MI), DPSC were infected with a retrovirus encoding the green fluorescent protein (GFP) and expanded ex vivo. Seven days after induction of myocardial infarction by coronary artery ligation, 1.5 x 10(6) GFP-DPSC were injected intramyocardially in nude rats. At 4 weeks, cell-treated animals showed an improvement in cardiac function, observed by percentage changes in anterior wall thickening left ventricular fractional area change, in parallel with a reduction in infarct size. No histologic evidence was seen of GFP+ endothelial cells, smooth muscle cells, or cardiac muscle cells within the infarct. However, angiogenesis was increased relative to control-treated animals. Taken together, these data suggest that DPSC could provide a novel alternative cell population for cardiac repair, at least in the setting of acute MI.

 

2007

Human dental pulp stem cells--isolation and long term cultivation.
Suchánek J, Soukup T, Ivancaková R, Karbanová J, Hubková V, Pytlík R, Kucerová L.

Acta Medica (Hradec Kralove)
2007;50(3):195-201
[full article]

Abstract: 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.

Morphostructural analysis of human follicular stem cells on highly porous bone hydroxyapatite scaffold.
Tetè S, Mastrangelo F, Carone L, Nargi E, Costanzo G, Vinci R, Burruano F, Tortorici S, Dadorante V, Caciagli F, Traini T, Gherlone E, Caraffa A, Salini V, Conti P, Ciccarelli R.

Int J Immunopathol Pharmacol
2007 Oct-Dec;20(4):819-26
[full article]

Abstract: In this study we investigated the in vitro behaviour, morphostructure and extracellular matrix synthesis of human dental follicular stem cells (hDFSCs) isolated from human dental bud, which resulted to be positive for mesenchymal markers (CD29, CD90, CD146 and CD166) by FACS analysis. Cells were analysed by light and electronic microscopy to evaluate their biological response either at week 1, that is before differentiation, or at weeks 3-6, when they had been cultured in osteogenic medium onto a highly porous natural scaffold material (Bio-Oss). Microscopy analysis of primary culture cells showed they had a mesenchymal stem cell-like morphostructure, spindle shaped, similar to the culture of mesenchymal stem cells derived from adult bone marrow. Also, after osteogenic differentiation, these analyses indicate typical osteoblast morphostructure and reveale a tri-dimensional organization of the cells and deposition of extracellular matrix (ECM) in close contact with biomaterial. This approach would allow to personalize the scaffold for bone tissue engineering in order to accelerate the process of osteogenesis.

Odontogenesis of Delta1 gene transfected human dental pulp stem cells
He F, Yang Z, Tan Y.

Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi
2007 Oct;21(10):1133-6
[full article]

OBJECTIVE: To investigate the heterotopic odontogenesis ability of Delta1 gene transfected human dental pulp stem cell (DPSC) and nano-hydroxyapatite/collagen (nHAC) composite scaffold.
METHODS: The cultured human DPSC was transfected with Delta1-enhanced green fluorescent protein recombinant retrovirus supernatant,and was selected by puromycin to obtain the positive cell clone. The experimental group contained the Delta1 transfected DPSC; however, the control group did not contain the Delta1 transfected DPSC but contained DPSC transfected with vectors only. The cells were seeded into the nHAC carriers and were cultured in the odonto-inductive medium. The growth of the transduced cells in the carriers was observed by the fluorescent phase contrast microscope and the scanning electron microscope (SEM). The cell-carrier composites were subcutaneously transplanted into the Delta1 transfected 8 nude mice (female, 8 weeks old). Eight weeks after operation, the composites were taken out and tested with the histological and the immunohistological methods.
RESULTS: Green fluorescence was observed in the cells in the experimental group, which were grown in the carriers by the fluorescent phase contrast microscope. Observed by SEM, great amounts of transduced DPSC were observed along the scaffold materials, even filling the porous structures of nHAC and secreting a lot of extracellular matrix. However, in the control group, much fewer cells were found in the carriers. All the 4 Delta1 transduced DPSC-nHAC composites produced dentin-like structures that lined the surfaces of some nHAC porous structures. The odontoblast-like cells extended the cytoplasmic processes into the dentinal matrix, which was interfaced with a pulp-like interstitial tissue infiltrated with the blood vessels. Dentin sialophosphoprotein was expressed in the odontoblast-like cells when immunohisochemistry was performed. The morphology of the control composite was a typical one of the fibrous connective tissue, and only a little dentin-like structure was found in 2 of the 8 control transplants.
CONCLUSION: DPSC can be used as the recipient cell of the Delta1 gene for expression and secretion of the Delta1 protein. The composites of the transfected cells and nHAC can induce heterotopic odontogenesis, which indicates that Delta1 is a novel candidate for the gene enhanced dentin-pulp composite engineering.

Coexpression of Notch3 and Rgs5 in the pericyte-vascular smooth muscle cell axis in response to pulp injury.
Lovschall H, Mitsiadis TA, Poulsen K, Jensen KH, Kjeldsen AL.

Int J Dev Biol
2007;51(8):715-21
[full article]

Abstract: Recent studies have shown that the pulp of human teeth contains a population of cells with stem cell properties and it has been suggested that these cells originate from pericytes. Molecules of the Notch signaling pathway regulate stem cell fate specification, while Rgs5 represents an excellent marker for pericytes. Pathological conditions such as dental trauma and carious lesion stimulate pulp stem cells to elaborate reparative dentin. Previous studies have shown that genes involved in the Notch pathway are activated in response to pulp injury in rodent and humans. To demonstrate the importance of pericytes as a source of stem cells during dental repair, we have studied Rgs5 and Notch3 mRNA expression by in situ hybridization in developing, adult intact and injured rodent teeth. Furthermore, we have examined the distribution of Notch3 protein in carious and injured human teeth using immunohistochemistry. Overlapping expression patterns of Rgs5 and Notch3 were observed during rodent tooth development as well as immediately after injury. Both genes were expressed in vascular structures during development and in perivascular and single capillary cells of injured teeth. However, the expression patterns of Rgs5 and Notch3 were different during tooth repair, with relatively extensive Rgs5 expression along the pericyte-vascular smooth muscle cell axis in central pulp arterioles. These results show co-expression of Rgs5 and Notch3 in pericytes of developing and injured teeth and furthermore indicate the importance of vascular-derived stem cells during pulp healing.

Dental pulp stem cells bioadhesivity: evaluation on mineral-trioxide-aggregate.
Trubiani O, D'Arcangelo C, Di Iorio D, Di Nardo Di Maio F, Caputi S.

Int J Immunopathol Pharmacol
2007 Jan-Mar;20(1 Suppl 1):81-6
[full article]

Abstract: Stem cells are undifferentiated cells that have the capacity to self-renew. They have been discovered in many adult tissues, including teeth. Dental Pulp Mesenchymal Stem Cells (DP-MSCs) are involved in dental repair by activation of growth factors, released after caries and have the ability to regenerate a dentin-pulp-like complex. The molecular/cellular research gives the possibility to grow new tissues and biological structures for clinical applications, providing cells for therapies including cell transplantation and tissue engineering. In this study DP-MSCs were derived from dental pulp of 10 donors. To evaluate material toxicity, after in vitro isolation, the cells were seeded on mineral trioxide aggregate (MTA). Initial light microscopy investigation of cells revealed no signs of cell death due to toxicity or infection, on the contrary the scaffolds supplied an excellent support for cell structures, the cells proliferated and adhered to substrate. Similar observation was seen in scanning electron microscopy, in particular the cells had proliferated and spread, covering a considerable part of the surface of the biomaterials investigated, with an elaborate form of attachment, in fact, the cells formed a continuous layer on the upper surface of the MTA. In conclusion, the aim of this study is to demonstrate that DP-MSCs combined with MTA could be a potential source for regenerative medicine, encouraging further study to evaluate the new dentin formation.

The state of the art in human dental stem cell research
Morsczeck C, Reichert TE, Völlner F, Gerlach T, Driemel O.

Mund Kiefer Gesichtschir
2007 Nov;11(5):259-66
[full article]

Abstract: 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.

Stem cells of dental pulp
Renard E, Lopez-Cazaux S, Guicheux J, Weiss P, Laboux O, Alliot-Licht B.

C R Biol
2007 Sep;330(9):635-43
[full article]

Abstract: Any clinician dreams to obtain the regeneration of the destroyed organ for his patient. In the human being, the regeneration of complex structures is not possible, except the liver and the bone marrow, which can be regenerated because of the presence of adult stem cells in these tissues. The stem cells have two principal properties: they ensure their self-renewal and they have the ability to differentiate into several cellular types. Using specific markers allowing the identification of the stem cells in bone marrow, stem cells were observed in dental pulp tissues. Although the origin, the identification, and the localization of these stem cells of dental pulp remain under consideration, the optimism in research on stem cells permits to believe that the knowledge on dental stem cells will lead to their use in therapeutics.

Tooth regeneration: implications for the use of bioengineered organs in first-wave organ replacement.
Nakahara T, Ide Y.

Hum Cell
2007 Aug;20(3):63-70
[full article]

Abstract: Experiments with animal models have shown that the tooth crown structure can be regenerated using tissue engineering techniques that combine tooth bud cells and biodegradable materials, or by using embryonic tissue and adult stem cells. Moreover, tooth roots and periodontal tissues have been reconstructed by grafting dental stem cells, which leads to the recovery of tooth function, suggesting that tooth regeneration will become possible in humans in the near future. The present article reviews current research on tooth regeneration, discusses a model of tooth replacement that could be used clinically, and proposes a new tooth regeneration approach that overcomes the difficulties associated with the tooth replacement model. Tooth regeneration is an important stepping stone in the establishment of engineered organ transplantation, which is one of the ultimate goals of regenerative therapies.

Mesenchymal progenitor cells in adult human dental pulp and their ability to form bone when transplanted into immunocompromised mice.
Otaki S, Ueshima S, Shiraishi K, Sugiyama K, Hamada S, Yorimoto M, Matsuo O.

Cell Biol Int
2007 Oct;31(10):1191-7
[full article]

Abstract: The technique of tissue engineering is developing for the restoration of lost tissues. This new technique requires cells that fabricate tissue. Mesenchymal stem cells in bone marrow have been used as the cell source for this technique; however, dental pulp cells have recently been shown to possess stem-cell-like properties. We earlier demonstrated that dental pulp cells proliferate and produce an extracellular matrix that subsequently becomes mineralized in vitro. We now report that such dental pulp cells (first to eighth passage) produced bone instead of dentin when those cells were implanted into subcutaneous sites in immunocompromised mice with HA/TCP powder as their carrier. This evidence shows that dental pulp cells are the common progenitors of odontoblasts and osteoblasts, or dental pulp cells are mesenchymal stem cells themselves. It is expected that dental pulp cells can be a useful candidate cell source for tissue engineering, and contain the potential of new therapeutic approaches for the restoration of damaged or diseased tissue.

Isolation and characterization of postnatal stem cells from human dental tissues.
Jo YY, Lee HJ, Kook SY, Choung HW, Park JY, Chung JH, Choung YH, Kim ES, Yang HC, Choung PH.

Tissue Eng
2007 Apr;13(4):767-73
[full article]

Abstract: It was reported that postnatal stem cells are present in adult tissues such as bone marrow, liver, muscle, dental pulp, and periodontal ligament. We isolated postnatal stem cells from human dental tissues such as dental pulp (DPSC), periodontal ligament (PDLSC), periapical follicle (PAFSC), and the surrounding mandibular bone marrow (MBMSC) to ascertain their properties. Immunocytochemistry proved the existence of stem cells in these cell populations using STRO-1 as a stem cell marker. These cells also expressed the mesenchymal stem cell (MSC) markers CD29 and CD44. The isolated cells showed self-renewal capabilities and colony-forming efficiency. Almost all of the dental stem cells showed optimal growth when they were cultured in alpha modification of Eagle's medium (alpha-MEM) supplemented with 10% fetal calf serum (FCS) and 100 microM ascorbic acid. Only the PAFSC showed increased proliferation in 20% FCS and 50 microM ascorbic acid. All of the dental stem cells were capable of differentiating into adipocytes and mineral nodule forming cells. MBMSC, in particular, showed much better mineralization compared to the others. These results indicate that MSCs exist in various tissues of the teeth and can differentiate into osteoblasts, adipocytes, and other kinds of cells with varying efficiency.

Regenerative endodontics: a review of current status and a call for action.
Murray PE, Garcia-Godoy F, Hargreaves KM.

J Endod
2007 Apr;33(4):377-90
[full article]

Abstract: Millions of teeth are saved each year by root canal therapy. Although current treatment modalities offer high levels of success for many conditions, an ideal form of therapy might consist of regenerative approaches in which diseased or necrotic pulp tissues are removed and replaced with healthy pulp tissue to revitalize teeth. Researchers are working toward this objective. Regenerative endodontics is the creation and delivery of tissues to replace diseased, missing, and traumatized pulp. This review provides an overview of regenerative endodontics and its goals, and describes possible techniques that will allow regenerative endodontics to become a reality. These potential approaches include root-canal revascularization, postnatal (adult) stem cell therapy, pulp implant, scaffold implant, three-dimensional cell printing, injectable scaffolds, and gene therapy. These regenerative endodontic techniques will possibly involve some combination of disinfection or debridement of infected root canal systems with apical enlargement to permit revascularization and use of adult stem cells, scaffolds, and growth factors. Although the challenges of introducing endodontic tissue engineering therapies are substantial, the potential benefits to patients and the profession are equally ground breaking. Patient demand is staggering both in scope and cost, because tissue engineering therapy offers the possibility of restoring natural function instead of surgical placement of an artificial prosthesis. By providing an overview of the methodological issues required to develop potential regenerative endodontic therapies, we hope to present a call for action to develop these therapies for clinical use.

In vitro stem cell cultures from human dental pulp and periodontal ligament: new prospects in dentistry.
Ballini A, De Frenza G, Cantore S, Papa F, Grano M, Mastrangelo F, Tetè S, Grassi FR.

Int J Immunopathol Pharmacol
2007 Jan-Mar;20(1):9-16
[full article]

Abstract: In spite of the vast knowledge of tooth development and of the various kinds of specialized bone/tooth-associated cells, the characteristics and properties of their precursor cell populations present in the postnatal organism are little known, as is their possible therapeutic use. Taken together dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) possess stem-cell-like qualities, including self-renewal capability and multi-lineage differentiation. Regenerative medicine is based on stem cells, signals and scaffolds. Transplantation of those cells, which can be obtained from an easily accessible tissue resource and expanded in vitro, holds promise as a therapeutic approach for reconstruction of tissues and bone in vivo.

Stem cells and the dental pulp: potential roles in dentine regeneration and repair.
Sloan AJ, Smith AJ.

Oral Dis
2007 Mar;13(2):151-7
[full article]

Abstract: The dentine-pulp complex displays exquisite regenerative potential in response to injury. The postnatal dental pulp contains a variety of potential progenitor/stem cells, which may participate in dental regeneration. A population of multipotent mesenchymal progenitor cells known as dental pulp stem cells with high proliferative potential for self-renewal has been described and may be important to the regenerative capacity of the tissue. The nature of the progenitor/stem cell populations in the pulp is of importance in understanding their potentialities and development of isolation or recruitment strategies, and allowing exploitation of their use in regeneration and tissue engineering. Various strategies will be required to ensure not only effective isolation of these cells, but also controlled signalling of their differentiation and regulation of secretory behaviour. Characterization of these cells and determination of their potentialities in terms of specificity of regenerative response will form the foundation for development of new clinical treatment modalities, whether involving directed recruitment of the cells and 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 will provide an innovative and novel biologically based new generation of clinical treatments for dental disease.

Multilineage potential of pulp stem cells from human young permanent teeth in vitro
Liu HS, Bai XW, Yang Y, Ge LH.

Beijing Da Xue Xue Bao
2007 Feb 18;39(1):41-5
[full article]

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.

 

2006

Multilineage differentiation potential of stem cells derived from human dental pulp after cryopreservation.
Zhang W, Walboomers XF, Shi S, Fan M, Jansen JA.

Tissue Eng
2006 Oct;12(10):2813-23
[full article]

Abstract: 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.

Isolation and characterization of a population of immature dental pulp stem cells expressing OCT-4 and other embryonic stem cell markers.
Kerkis I, Kerkis A, Dozortsev D, Stukart-Parsons GC, Gomes Massironi SM, Pereira LV, Caplan AI, Cerruti HF.

Cells Tissues Organs
2006;184(3-4):105-16
[full article]

Abstract: 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.

Stem cells in dental practice: perspectives in conservative pulp therapies.
Casagrande L, Mattuella LG, de Araujo FB, Eduardo J.

J Clin Pediatr Dent
2006 Fall;31(1):25-7
[full article]

Abstract: Stem cells are undifferentiated cells that have the capacity to self-renew. They have been discovered in many adult tissues, including teeth. The Dental Pulp Stem Cells are involved in dentinal repair by activation of growth factors, released after caries process and have the ability to regenerate the dentin-pulp-like complex. The molecular/cellular research raises the possibilities to grow new tissues and biological structures for clinical application, providing cells for therapies including cell transplantation and tissue engineering.

Regenerative dental medicine: stem cells and tissue engineering in dentistry.
Reed JA, Patarca R.

J Environ Pathol Toxicol Oncol
2006;25(3):537-69
[full article]

Abstract: The dawn of this century is brightened by the growing understanding and experimentation with stem cells as primary tools in the expanding regenerative medicine and tissue engineering revolution. The tradition of using prosthetic artificial implants to restore lost or damaged dental tissue will gradually be supplanted by more natural alternatives, including biological tooth replacement or induction. The practice of dentistry is likely to be revolutionized by biological therapies based on growth and differentiation factors that accelerate and/or induce a natural biological regeneration. This prospect has flourished from the gained knowledge provided by the molecular biological characterization of the genetic makeup of human cells and from a growing understanding of the effect of environmental factors. Prevention of dental diseases will also gain new ground as more insight is gained into the genetic makeup of microbial pathogens, their interactions with the host, and the host repair mechanisms. This review summarizes current knowledge, barriers, and challenges in the clinical use of stem cells with an emphasis on applications in dentistry.

Craniofacial tissue engineering by stem cells.
Mao JJ, Giannobile WV, Helms JA, Hollister SJ, Krebsbach PH, Longaker MT, Shi S.

J Dent Res
2006 Nov;85(11):966-79
[full article]

Abstract: Craniofacial tissue engineering promises the regeneration or de novo formation of dental, oral, and craniofacial structures lost to congenital anomalies, trauma, and diseases. Virtually all craniofacial structures are derivatives of mesenchymal cells. Mesenchymal stem cells are the offspring of mesenchymal cells following asymmetrical division, and reside in various craniofacial structures in the adult. Cells with characteristics of adult stem cells have been isolated from the dental pulp, the deciduous tooth, and the periodontium. Several craniofacial structures--such as the mandibular condyle, calvarial bone, cranial suture, and subcutaneous adipose tissue--have been engineered from mesenchymal stem cells, growth factor, and/or gene therapy approaches. As a departure from the reliance of current clinical practice on durable materials such as amalgam, composites, and metallic alloys, biological therapies utilize mesenchymal stem cells, delivered or internally recruited, to generate craniofacial structures in temporary scaffolding biomaterials. Craniofacial tissue engineering is likely to be realized in the foreseeable future, and represents an opportunity that dentistry cannot afford to miss.

Formation of odontoblast-like cells from cultured human dental pulp cells on dentin in vitro.
Huang GT, Shagramanova K, Chan SW.

J Endod
2006 Nov;32(11):1066-73
[full article]

Abstract: Recent characterization of human dental pulp stem cells has shed new light on the understanding of the odontoblastic lineage. The purpose of the study was to characterize human adult dental pulp cells isolated and cultured in vitro and to examine the cell differentiation potential grown on dentin. We observed that some pulp cells isolated with an enzyme-digestion approach proliferated at a similar rate as the immortal cell line NIH 3T3. Population doubling time (PDt) for pulp cells at passage 3 was 22.6 +/- 0.5 hours and for NIH 3T3 was 23.1 +/- 2.3 hours. The pulp cells formed mineral nodules stimulated with dexamethasone or dexamethasone plus 1,25-dihydroxyvitamin D3. Pulp cells, after being seeded onto mechanically and chemically treated dentin surface, appeared to establish an odontoblast-like morphology with a cytoplasmic process extending into a dentinal tubule revealed by scanning electron microscopy analysis. Our data demonstrated the formation of cells with odontoblastic morphologies on existing dentin, suggesting that isolated human pulp stem cells may differentiate into odontoblasts on dentin in vitro.

Stem cell properties of human periodontal ligament cells.
Nagatomo K, Komaki M, Sekiya I, Sakaguchi Y, Noguchi K, Oda S, Muneta T, Ishikawa I.

J Periodontal Res
2006 Aug;41(4):303-10
[full article]

BACKGROUND AND OBJECTIVE: Stem cells have been used for regenerative therapies in various fields. The proportion of cells that possess stem cell properties in human periodontal ligament (PDL) cells is not yet well understood. In this study, we quantitatively characterized human PDL cells to clarify their stem cell properties, including self-renewal, multipotency, and stem cell marker expression.
MATERIAL AND METHODS: PDL cells were obtained from extracted premolar or wisdom teeth, following which a proliferation assay for self-renewal, a differentiation assay for multipotency, immunostaining for STRO-1, and fluorescence-activated cell sorter (FACS) analysis for stem cell markers (including CD105, CD166, and STRO-1) were performed.
RESULTS: Approximately 30% of 400 PDL cells were found to possess replicative potential and formed single-cell colonies, and 30% of these colonies displayed positive staining for STRO-1, 20% differentiated into adipocytes and 30% differentiated into osteoblasts. FACS analysis revealed that PDL cells, including cell populations, expressed the stem cell markers CD105, CD166, and STRO-1.
CONCLUSION: The findings of this study indicated that PDL cells possess crucial stem cell properties, such as self-renewal and multipotency, and express the mesenchymal stem cell markers CD105, CD166, and STRO-1 on their cell surface, although there were some variations. Thus, PDL cells can be used for periodontal regenerative procedures.

Long-term cryopreservation of dental pulp stem cells (SBP-DPSCs) and their differentiated osteoblasts: a cell source for tissue repair.
Papaccio G, Graziano A, d'Aquino R, Graziano MF, Pirozzi G, Menditti D, De Rosa A, Carinci F, Laino G.

J Cell Physiol
2006 Aug;208(2):319-25
[full article]

Abstract: 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.

Cluster analysis and gene expression profiles: a cDNA microarray system-based comparison between human dental pulp stem cells (hDPSCs) and human mesenchymal stem cells (hMSCs) for tissue engineering cell therapy.
Yamada Y, Fujimoto A, Ito A, Yoshimi R, Ueda M.

Biomaterials
2006 Jul;27(20):3766-81
[full article]

Abstract: We investigated gene expression patterns and functional classifications regarding the clusters of human dental pulp stem cells (hDPSCs) and human mesenchymal stem cells (hMSCs)--which possess a multipotent ability--because little is known about the precise moleculobiological clues by which these cells activate their differentiating ability or functionality to eventually form dentin and bone, respectively. We first verified the expressions of the alkaline phosphatase (ALP) gene, dentin matrix protein 1 (DMP-1), and dentinsialophosphoprotein (DSPP) by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) and consequently discovered the high expressions of these genes. Total RNA was also followed by hybridization with a human microarray system consisting of 12,814 genes. Analyses of gene expression patterns indicated several genes which encode extracellular matrix components, cell adhesion molecules, growth factors, and transcription regulators. Functional and clustering analyses of differences in gene expression levels revealed cell signaling, cell communication, or cell metabolism. In the future, information on the gene expression patterns of hDPSCs and hMSCs might be useful in determining the detailed functional roles of the relevant genes and applicable to stem cell therapies, and these cells could also be used as multipotent cell sources for gene technology and tissue engineering technology.

A review of new developments in tissue engineering therapy for periodontitis.
Nakahara T.

Dent Clin North Am
2006 Apr;50(2):265-76, ix-x
[full article]

Abstract: This article focuses on recent advances in the regeneration of periodontium using tissue engineering and examines new technologies that will lead to further advances in periodontal therapy. The various advantages and drawbacks of protein-based, cell-based, and genetic-engineering approaches are evaluated. The debate between those who aim to regenerate periodontal tissues and researchers who have focused on the reconstitution of structural elements of the teeth is examined. The isolation of human dental stem cells from deciduous and adult wisdom teeth might hold the key to allowing the replacement of teeth and the regeneration of supporting tissue. The combination of scientific research, following on from advances in other fields, with clinical research in dentistry could yield a solution to the debilitating and widespread problem of periodontitis.

Human dental pulp cell culture and cell transplantation with an alginate scaffold.
Kumabe S, Nakatsuka M, Kim GS, Jue SS, Aikawa F, Shin JW, Iwai Y.

Okajimas Folia Anat Jpn
2006 Feb;82(4):147-55
[full article]

Abstract: Many studies on tissue stem cells have been conducted in the field of regenerative medicine, and some studies have indicated that cultured dental pulp mesenchymal cells secrete dentin matrix. In the present study we used alginate as a scaffold to transplant subcultured human dental pulp cells subcutaneously into the backs of nude mice. We found that when beta-glycerophosphate was added to the culture medium, dentin sialophosphoprotein mRNA coding dentin sialoprotein (DSP) was expressed. An increase in alkaline phosphatase, which is an early marker for odontoblast differentiation, was also demonstrated. At 6 weeks after implantation the subcutaneous formation of radio-opaque calcified bodies was observed in situ. Immunohistochemical and fine structure studies identified expression of type I collagen, type III collagen, and DSP in the mineralizing transplants. Isolated odontoblast-like cells initiated dentin-like hard tissue formation and scattered autolyzing apoptotic cells were also observed in the transplants. The study showed that subcultured dental pulp cells actively differentiate into odontoblast-like cells and induce calcification in an alginate scaffold.

Gene expression of runx2, Osterix, c-fos, DLX-3, DLX-5, and MSX-2 in dental follicle cells during osteogenic differentiation in vitro.
Morsczeck C.

Calcif Tissue Int
2006 Feb;78(2):98-102
[full article]

Abstract: Recently, osteogenic precursor cells were isolated from human dental follicles, which differentiate into cementoblast- or osteoblast- like cells under in vitro conditions. However, mechanisms for osteogenic differentiation are not known in detail. Dental follicle cell long-term cultures supplemented with dexamethasone or with insulin resulted in mineralized nodules, whereas no mineralization or alkaline phosphatase activity was detected in the control culture without an osteogenic stimulus. A real-time reverse-transcriptase polymerase chain reaction (PCR) analysis was developed to investigate gene expression during osteogenic differentiation in vitro. Expression of the alkaline phosphatase (ALP) gene was detected during differentiation in the control culture and was similar to that in cultures with dexamethasone and insulin. DLX-3, DLX-5, runx2, and MSX-2 are differentially expressed during osteogenic differentiation in bone marrow mesenchymal stem cells. In dental follicle cells, gene expression of runx2, DLX-5, and MSX-2 was unaffected during osteogenic differentiation in vitro. Osteogenic differentiation appeared to be independent of MSX-2 expression; the same was true of runx2 and DLX-5, which were protagonists of osteogenic differentiation and osteocalcin promoter activity in bone marrow mesenchymal stem cells. Like in bone marrow-derived stem cells, DLX-3 gene expression was increased in dental follicle cells during osteogenic differentiation but similar to control cultures. However, gene expression of osterix was not detected in dental follicle cells during osteogenic differentiation; this gene is expressed during osteogenic differentiation in bone marrow stem cells. These real-time PCR results display molecular mechanisms in dental follicle precursor cells during osteogenic differentiation that are different from those in bone marrow-derived mesenchymal stem cells.

 

2005

Multipotent mesenchymal stem cells with immunosuppressive activity can be easily isolated from dental pulp.
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.

Transplantation
2005 Sep 27;80(6):836-42
[full article]

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.

The application of tissue engineering to regeneration of pulp and dentin in endodontics.
Nakashima M, Akamine A.

J Endod
2005 Oct;31(10):711-8
[full article]

Abstract: Caries, pulpitis, and apical periodontitis increase health care costs and attendant loss of economic productivity. They ultimately result in premature tooth loss and therefore diminishing the quality of life. Advances in vital pulp therapy with pulp stem/progenitor cells might give impetus to regenerate dentin-pulp complex without the removal of the whole pulp. Tissue engineering is the science of design and manufacture of new tissues to replace lost parts because of diseases including cancer and trauma. The three key ingredients for tissue engineering are signals for morphogenesis, stem cells for responding to morphogens and the scaffold of extracellular matrix. In preclinical studies cell therapy and gene therapy have been developed for many tissues and organs such as bone, heart, liver, and kidney as a means of delivering growth factors, cytokines, or morphogens with stem/progenitor cells in a scaffold to the sites of tissue injury to accelerate and/or induce a natural biological regeneration. The pulp tissue contains stem/progenitor cells that potentially differentiate into odontoblasts in response to bone morphogenetic proteins (BMPs). There are two strategies to regenerate dentin. First, is in vivo therapy, where BMP proteins or BMP genes are directly applied to the exposed or amputated pulp. Second is ex vivo therapy and consists of isolation of stem/progenitor cells from pulp tissue, differentiation into odontoblasts with recombinant BMPs or BMP genes and finally transplanted autogenously to regenerate dentin. This review is focused on the recent progress in this area and discusses the barriers and challenges for clinical utility in endodontics.

Cellular cardiomyoplasty for myocardial regeneration.
Chachques JC, Salanson-Lajos C, Lajos P, Shafy A, Alshamry A, Carpentier A.

Asian Cardiovasc Thorac Ann
2005 Sep;13(3):287-96
[full article]

Abstract: The evolving challenge of managing patients with congestive heart failure is the need to develop new therapeutic strategies. The cellular, molecular, and genetic approaches investigated aim to reinforce the weak, failing heart muscle while restoring its functional potential. This approach is principally cellular therapy (i.e. cellular cardiomyoplasty), the preferred therapeutic choice because of its clinical applicability and regenerative capacity. Different stem cells: bone marrow cells, skeletal and smooth muscle cells, vascular endothelial cells, mesothelial cells, adipose tissue stroma cells, dental stem cells, and embryonic and fetal cells, have been proposed for regenerative medicine and biology. Stem cell mobilization with G-CSF cytokine was also proposed as a single therapy for myocardial infarction. We investigated the association of cell therapy with electrostimulation (dynamic cellular cardiomyoplasty), the use of autologous human serum for cell cultures, and a new catheter for simultaneous infarct detection and cell delivery. Our team conducted cell-based myogenic and angiogenic clinical trials for chronic ischemic heart disease. Cellular cardiomyoplasty constitutes a new approach for myocardial regeneration; the ultimate goal is to avoid the progression of ventricular remodeling and heart failure for patients presenting with ischemic and non-ischemic cardiomyopathies.

Identification and isolation of human dental pulp stem cells
Yang XC, Fan MW.

Zhonghua Kou Qiang Yi Xue Za Zhi
2005 May;40(3):244-7
[full article]

OBJECTIVE: To isolate and cultivate human dental pulp stem cells (DPSCs).
METHODS: Pulp tissue was removed from healthy young human teeth extracted for orthodontic purposes. The pulp was digested by Type I collagenase and dispase. Then single-cell suspensions were obtained by filter and cultivated. The clones were identified by expression of STRO-1. Under the conditions of inducement, clones were identified by activity of alkaline phosphatase (ALP), formation of mineralized nodule and expression of dentin sialoprotein (DSP), and by Oil Red-O dyeing and expressing of PPARr2.
RESULTS: The clones had positive expression of STRO-1. When stimulated to differentiation, these cells took on dramatically high activity of ALP, had the ability of mineralization and expressed DSP. These cells also had ability to trans-differentiate into adipocytes.
CONCLUSION: There are stem cells in human dental pulp tissues, which can be isolated and cultivated.

Isolation of precursor cells (PCs) from human dental follicle of wisdom teeth.
Morsczeck C, Götz W, Schierholz J, Zeilhofer F, Kühn U, Möhl C, Sippel C, Hoffmann KH.

Matrix Biol
2005 Apr;24(2):155-65
[full article]

Abstract: The dental follicle is an ectomesenchymal tissue surrounding the developing tooth germ. It is believed that this tissue contains stem cells and lineage committed progenitor cells or precursor cells (PCs) for cementoblasts, periodontal ligament cells, and osteoblasts. In this study, we report the isolation of PCs derived from dental follicle of human third molar teeth. These fibroblast-like, colony forming and plastic adherent cells expressed putative stem cell markers Notch-1 and Nestin. We compared gene expressions of PCs, human mesenchymal stem cells (hMSCs), periodontal ligament cells (PDL-cells) and osteoblasts (MG63) for delimitation of PCs. Interestingly, PCs expressed higher amounts of insulin-like growth factor-2 (IGF-2) transcripts than hMSCs. Differentiation capacity was demonstrated under in vitro conditions for PCs. Long-term cultures with dexamethasone produced compact calcified nodules or appeared as plain membrane structures of different dimensions consisting of a connective tissue like matrix encapsulated by a mesothelium-like cellular structure. PCs differentially express osteocalcin (OCN) and bone sialoprotein (BS) after transplantation in immunocompromised mice but without any sign of cementum or bone formation. Therefore, our results demonstrate that cultured PCs are unique undifferentiated lineage committed cells residing in the periodontium prior or during tooth eruption.

 

2004

Stem cell responses in tooth regeneration.
Murray PE, Garcia-Godoy F.

Stem Cells Dev
2004 Jun;13(3):255-62
[full article]

Abstract: Scientific advances in the creation of restorative biomaterials, in vitro cell culture technology, tissue grafting, tissue engineering, molecular biology, and the human genome project provide the basis for the introduction of new technologies into dentistry. This review is intended to facilitate the development of stem cell therapy for use with established therapeutic modalities to restore and regenerate oral tissues. Teeth have been shown to mineralize in response to injury for many decades, but only in recent years has the position of the stem cells been localized around blood vessels. The cells have been identified as myofibroblastoid pericytes. The ability to control the differentiation and proliferation of these cells is being examined to create stem cell therapies that can solve dental problems more effectively than current treatment regimes. Although the problems of introducing these technologies are substantial, the potential benefits to patients and the profession are equally promising - a cure for caries and diseases, a cure for oral cancer, correction of congenital defects, and the regeneration of teeth and tissues to restore oral functions. The purpose of this review is to describe how these new technologies can most usefully be employed in dentistry to enable clinicians to satisfy patient demand for a nondefective dentition.

The characteristics of cultured dental pulp cells and the localization of dental pulp stem cells
Liu SH, Wei FC, Sun SZ, Zhang CY, Liu YS.

Shanghai Kou Qiang Yi Xue
2004 Apr;13(2):106-9
[full article]

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.

 

2003

Developmental biology and building a tooth.
Thesleff I.

Quintessence Int
2003 Sep;34(8):613-20
[full article]

Abstract: During the last 15 years, we have started to understand tooth development at the gene level. The list of genes known to regulate the position, shape, or number of teeth is lengthening rapidly. Interestingly, so far all these genes have important functions in the mediation of cell communication, which is generally considered the most important mechanism driving embryonic development. The communication is mediated by small signal molecules that are sent to nearby cells, thereby affecting their behavior and advancing differentiation. There are dozens of different signals and their receptors and target genes, which together form complicated signaling networks. The defects in several human conditions affecting tooth development have been identified recently, and these genes have turned out to be necessary components of signaling networks. Experimental studies using transgenic mice as models for human syndromes such as ectodermal and cleidocranial dysplasia have pinpointed the exact roles of the disease genes and indicated ways for possible new therapies. It is also possible that by combining the knowledge of molecular regulation of tooth development with the recent breakthroughs in stem cell research, dreams of building new teeth in dental practice may come true in the future.

Stem cells and tissue engineering: prospects for regenerating tissues in dental practice.
Thesleff I, Tummers M.

Med Princ Pract
2003;12 Suppl 1:43-50
[full article]

Abstract: In general, human tissues have a very limited potential to regenerate. However, recent progress in stem cell research and in tissue engineering promises novel prospects for tissue regeneration in dental practice in the future. Stem cells have been discovered in many adult tissues, including teeth, and stem cells from embryos have the potential to form all adult tissues. Embryonic stem cells can now be cultured and even produced from adult cells by the nuclear transfer method. Due to the rapid progress of research in molecular biology, particularly in the field of developmental biology, we are now starting to understand at the level of genes and molecules how the development of dental tissues is regulated. For instance, specific signal molecules have been identified which regulate the development of teeth and bones from progenitor cells. This information is already being used for the generation of dentoalveolar tissues in vitro and in vivo. Could we perhaps grow new enamel, dentine, periodontal ligament, bone, or even whole new teeth for our patients in the future?