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Objective: To investigate the biological regulatory function of Gremlin1 (GREM1) and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein eta (YWHAH) in dental pulp stem cells (DPSCs), and determine the underlying molecular mechanism involved., Methods: Alkaline phosphatase (ALP) activity, alizarin red staining, scratch migration assays and in vitro and in vivo osteo-/dentinogenic marker detection of bone-like tissue generation in nude mice were used to assess osteo-/dentinogenic differentiation. Coimmunoprecipitation and polypeptide microarray assays were employed to detect the molecular mechanisms involved., Results: The data revealed that knockdown of GREM1 promoted ALP activity, mineralisation in vitro and the expression of osteo-/dentinogenic differentiation markers and enhanced osteo-/ dentinogenesis of DPSCs in vivo. GREM1 bound to YWHAH in DPSCs, and the binding site was also identified. Knockdown of YWHAH suppressed the osteo-/dentinogenesis of DPSCs in vitro, and overexpression of YWHAH promoted the osteo-/dentinogenesis of DPSCs in vitro and in vivo., Conclusion: Taken together, the findings highlight the critical roles of GREM1-YWHAH in the osteo-/dentinogenesis of DPSCs.

Previous studies have demonstrated that several types of human stem cells of non-dental origin can be induced to differentiate into enamel-secreting ameloblasts after recombined with mouse embryonic dental mesenchyme. However, the successful rate of ameloblastic differentiation is about rather low, which presents a major obstacle for future stem cell-based whole tooth bioengineering. Previous studies have shown that cultures at reduced temperature could improve the differentiation capability of stem cells in tissue engineering. In this study, we systematically investigated the effects of low temperature on the viability, proliferation and stemness of human keratinocytes stem cells (hKSCs) in cell culture and further examined ameloblastic differentiation of the hKSCs in human-mouse recombinant chimeric tooth germs. Our results demonstrated that low temperature indeed reduces growth rate and maintains healthy undifferentiated morphology of hKSCs without any effects on cell viability. Moreover, examination of stemness makers revealed improved stemness of hKSCs cultured at low temperature with increased expression of stemness markers K15, CD29 and p63 and decreased expression differentiation marker K10, as compared to those cultured at 37 °C. These low temperature treated hKSCs, when recombined with mouse embryonic dental mesenchyme, exhibited significantly increased rate (40%) of ameloblastic differentiation, as compared to that (17%) in tissue recombinants with those hKSCs treated at standard temperature. Our studies demonstrate that low temperature cell culture improves the stemness and plasticity of hKSCs, which in turn enhances ameloblastic differentiation capability of the stem cells in bioengineered teeth.

Continuous growth of the rodent incisor is enabled by epithelial and mesenchymal stem cells (ESCs and MSCs) which unceasingly replenish enamel and dentin, respectively, that wear by persistent animal gnawing. Lineage tracing studies have provided evidence that ESCs contribute to all epithelial lineages of the tooth in vivo. Meanwhile, in the mouse incisor, MSCs continuously contribute to odontoblast lineage and tooth growth. However, in vitro manipulation of ESCs has shown little progress, mainly due to lack of appropriate protocol to successfully isolate, culture, expand, and differentiate ESCs in vitro without using the co-culture system. In this chapter we describe the isolation of the Sox2-GFP+ cell population that is highly enriched in ESCs. Isolated cells can be used for various types of analyses, including in vitro culture, single cell-related analyses, etc. Furthermore, we describe ways to obtain populations enriched in the incisor MSCs using FACS sorting of antibody-labeled cells. Easily accessible FACS sorting enables easy and relatively fast isolation of the cells labeled by the fluorescent protein.

Currently regeneration of tooth and periodontal damage still remains great challenge. Stem cell-based tissue engineering raised novel therapeutic strategies for tooth and periodontal repair. Stem cells for tooth and periodontal regeneration include dental pulp stem cells (DPSCs), periodontal ligament stem cells (PDLSCs), stem cells from the dental apical papilla (SCAPs), and stem cells from human exfoliated deciduous teeth (SHEDs), dental follicle stem cells (DFSCs), dental epithelial stem cells (DESCs), bone marrow mesenchymal stem cells (BMMSCs), adipose-derived stem cells (ADSCs), embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). To date, substantial advances have been made in stem cell-based tooth and periodontal regeneration, including dentin-pulp, whole tooth, bioroot and periodontal regeneration. Translational investigations have been performed such as dental stem cell banking and clinical trials. In this review, we present strategies for stem cell-based tissue engineering for tooth and periodontal repair, and the translational studies., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. All rights reserved.)

Background: Tooth loss occurs with age and significantly impacts the quality of elderly's life both physically and psychologically. It has been well known that odontogenesis is a complicated process with sequential and reciprocal interactions between epithelial and mesenchymal tissues and different types of dental tissue-derived stem cells involve in it. However, only a small portion of the intricate mechanisms has been defined nowadays. Among them, epigenetics has become an increasingly important mechanism for tooth development and regeneration., Objective: This review aims at illustrating the function of epigenetic regulation in odontogenesis, which plays an important role in dental tissue-derived stem cell self-renewal and differentiation nowadays and would be a new strategy for tooth regeneration., Results: In this review, we introduced the natural process of tooth development and the functions of stem cells involved in. Furthermore, we summarized the current knowledge on epigenetic regulation including DNA methylation, histone modification, and non-coding RNAs during odontogenesis, providing the theoretical basis for tooth regeneration., Conclusion: Along with a deeper understanding of odontogenesis, the epigenetic mechanism involved in has become increasingly important. Therefore, it's necessary to further study the functions of epigenetic regulation in tooth development and regeneration, which may make tooth regeneration a reality in the future., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Stem cells from the apical papilla (SCAPs) are important for the formation and regeneration of root dentin. Here, we examined the expression of Notch signaling components in SCAPs and investigated crosstalk between microRNA miR-34aand Notch signaling during cell differentiation. We found that human SCAPs express NOTCH2, NOTCH3, JAG2, DLL3, and HES1, and we tested the relationship between Notch signaling and both cell differentiation and miR-34a expression. NOTCH activation in SCAPs inhibited cell differentiation and up-regulated the expression of miR-34a, whereas miR-34a inhibited Notch signaling in SCAPs by directly targeting the 3'UTR of NOTCH2 and HES1 mRNA and suppressing the expression of NOTCH2, N2ICD, and HES1. DSPP, RUNX2, OSX, and OCN expression was consequently up-regulated. Thus, Notch signaling in human SCAPs plays a vital role in maintenance of these cells. miR-34a interacts with Notch signaling and promotes both odontogenic and osteogenic differentiation of SCAPs., (© International & American Associations for Dental Research.)

Objective: Autologous therapy via stem cell-based tissue regeneration is an aim to rebuild natural teeth. One option is the use of adult stem cells from the dental pulp (DPSCs), which have been shown to differentiate into several types of tissue in vitro and in vivo, especially into tooth-like structures. DPSCs are mainly isolated from the dental pulp of third molars routinely extracted for orthodontic reasons. Due to the extraction of third molars at various phases of life, DPSCs are isolated at different developmental stages of the tooth., Design: The present study addressed the question whether DPSCs from patients of different ages were similar in their growth characteristics with respect to the stage of tooth development. Therefore DPSCs from third molars of 12-30 year-old patients were extracted, and growth characteristics, e.g. doubling time and maximal cell division potential were analysed. In addition, pulp and hard dental material weight were recorded., Results: Irrespective of the age of patients almost all isolated cells reached 40-60 generations with no correlation between maximal cell division potential and patient age. Cells from patients <22 years showed a significantly faster doubling time than the cells from patients ≥22 years., Conclusion: The age of patients at the time of stem cell isolation is not a crucial factor concerning maximal cell division potential, but does have an impact on the doubling time. However, differences in individuals regarding growth characteristics were more pronounced than age-dependent differences., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In recent years, scientists in almost every medical sector moved the focus to tissue transplantation and stem cell-based therapies for organ and tissue regeneration. In dentistry, it is of great interest in this regard to restore natural teeth with the help of stem cell-based regeneration of soft tissues and hard tooth structures. Many studies have been published in which structures resembling teeth were constructed using stem cells. In most of these studies, carrier materials (scaffolds) were used, which were colonized with cells and then implanted into an animal. Apart from this, scaffold-free approaches based on cell aggregation have also been published. Although animal studies on tooth regeneration have been very promising, much more research is needed until this can be applied in human., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Background: Human epithelium-derived stem cells and induced pluripotent stem cells (hiPSCs) possess the capability to support tooth formation and differentiate into functional enamel-secreting ameloblasts, making them promising epithelial-component substitutes for future human tooth regeneration. However, current tissue recombination approaches are not only technically challenging, requiring precise induction procedures and sophisticated microsurgery, but also exhibit low success rates in achieving tooth formation and ameloblastic differentiation. Methods: Suspended human keratinocyte stem cells (hKSCs) or cells from three hiPSC lines were directly mixed with dissociated embryonic mouse dental mesenchymal cells (mDMCs) that possess odontogenic potential in different proportions and reaggregated them to construct bioengineered tooth germs. The success rates of tooth formation and ameloblastic differentiation were confirmed after subrenal culture. The sorting capability, sequential development, and ameloblastic differentiation of stem cells were examined via GFP tracing, RT-PCR, and histological analysis, respectively. Results: Our reaggregation approach achieved an impressive success rate of more than 90% in tooth formation and 100% in ameloblastic differentiation when the chimeric tooth germs contained 1%~10% hKSCs or 5% hiPSCs. In addition, we observed that hiPSCs, upon exposure to mDMCs, initially transformed into epidermal cells, as indicated by KRT14 and CD29 expression, before progressing into dental epithelial cells, as indicated by SP6 and SHH expression. We also found that epithelial-derived hiPSCs, when reaggregated with mDMCs, were more favorable for tooth formation than their mesenchymal-derived counterparts. Conclusions: This study establishes a simplified yet highly effective cell-cell reaggregation strategy for inducing stem cells to support tooth formation and differentiate into functional ameloblasts, paving the way for novel approaches for the development of stem cell-based tooth organoids and bioengineered tooth germs in vitro. [ABSTRACT FROM AUTHOR]

Objective: To investigate the biological regulatory function of Gremlin1 (GREM1) and tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein eta (YWHAH) in dental pulp stem cells (DPSCs), and determine the underlying molecular mechanism involved. Methods: Alkaline phosphatase (ALP) activity, alizarin red staining, scratch migration assays and in vitro and in vivo osteo-/dentinogenic marker detection of bone-like tissue generation in nude mice were used to assess osteo-/dentinogenic differentiation. Coimmunoprecipitation and polypeptide microarray assays were employed to detect the molecular mechanisms involved. Results: The data revealed that knockdown of GREM1 promoted ALP activity, mineralisation in vitro and the expression of osteo-/dentinogenic differentiation markers and enhanced osteo-/ dentinogenesis of DPSCs in vivo. GREM1 bound to YWHAH in DPSCs, and the binding site was also identified. Knockdown of YWHAH suppressed the osteo-/dentinogenesis of DPSCs in vitro, and overexpression of YWHAH promoted the osteo-/dentinogenesis of DPSCs in vitro and in vivo. Conclusion: Taken together, the findings highlight the critical roles of GREM1-YWHAH in the osteo-/dentinogenesis of DPSCs. [ABSTRACT FROM AUTHOR]

Most tooth‐bearing non‐mammalian vertebrates have the capacity to replace their teeth throughout life. This capacity was lost in mammals, which replace their teeth only once at most. Not surprisingly, continuous tooth replacement has attracted much attention. Classical morphological studies (e.g. to analyse patterns of replacement) are now being complemented by molecular studies that investigate the expression of genes involved in tooth formation. This review focuses on ray‐finned fish (actinopterygians), which have teeth often distributed throughout the mouth and pharynx, and more specifically on teleost fish, the largest group of extant vertebrates. First we highlight the diversity in tooth distribution and in tooth replacement patterns. Replacement tooth formation can start from a distinct (usually discontinuous and transient) dental lamina, but also in the absence of a successional lamina, e.g. from the surface epithelium of the oropharynx or from the outer dental epithelium of a predecessor tooth. The relationship of a replacement tooth to its predecessor is closely related to whether replacement is the result of a prepattern or occurs on demand. As replacement teeth do not necessarily have the same molecular signature as first‐generation teeth, the question of the actual trigger for tooth replacement is discussed. Much emphasis has been laid in the past on the potential role of epithelial stem cells in initiating tooth replacement. The outcome of such studies has been equivocal, possibly related to the taxa investigated, and the permanent or transient nature of the dental lamina. Alternatively, replacement may result from local proliferation of undifferentiated progenitors, stimulated by hitherto unknown, perhaps mesenchymal, factors. So far, the role of the neurovascular link in continuous tooth replacement has been poorly investigated, despite the presence of a rich vascularisation surrounding actinopterygian (as well as chondrichthyan) teeth and despite a complete arrest of tooth replacement after nerve resection. Lastly, tooth replacement is possibly co‐opted as a process to expand the number of teeth in a dentition ontogenetically whilst conserving features of the primary dentition. That neither a dental lamina, nor stem cells appear to be required for tooth replacement places teleosts in an advantageous position as models for tooth regeneration in humans, where the dental lamina regresses and epithelial stem cells are considered lost. [ABSTRACT FROM AUTHOR]

Research on tooth regeneration using human-induced pluripotent stem cells (hiPSCs) is valuable for autologous dental regeneration. Acquiring mesenchymal and epithelial cells as a resource for dental regeneration is necessary because mesenchymal–epithelial interactions play an essential role in dental development. We reported the establishment of hiPSCs-derived dental epithelial-like cell (EPI-iPSCs), but hiPSCs-derived dental mesenchymal stem cells (MSCs) have not yet been reported. This study was conducted to establish hiPSCs-derived MSCs and to differentiate them into dental cells with EPI-iPSCs. Considering that dental MSCs are derived from the neural crest, hiPSCs were induced to differentiate into MSCs through neural crest formation to acquire the properties of dental MSCs. To differentiate hiPSCs into MSCs through neural crest formation, established hiPSCs were cultured and differentiated with PA6 stromal cells and differentiated hiPSCs formed neurospheres on ultralow-attachment plates. Neurospheres were differentiated into MSCs in serum-supplemented medium. Neural crest-mediated MSCs (NC-MSCs) continuously showed typical MSC morphology and expressed MSC markers. After 8 days of odontogenic induction, the expression levels of odontogenic/mineralization-related genes and dentin sialophosphoprotein (DSPP) proteins were increased in the NC-MSCs alone group in the absence of coculturing with dental epithelial cells. The NC-MSCs and EPI-iPSCs coculture groups showed high expression levels of amelogenesis/odontogenic/mineralization-related genes and DSPP proteins. Furthermore, the NC-MSCs and EPI-iPSCs coculture group yielded calcium deposits earlier than the NC-MSCs alone group. These results indicated that established NC-MSCs from hiPSCs have dental differentiation capacity with dental epithelial cells. In addition, it was confirmed that hiPSCs-derived dental stem cells could be a novel cell source for autologous dental regeneration. [ABSTRACT FROM AUTHOR]

The odontogenic differentiation of dental pulp stem cells (DPSCs), which is vital for tooth regeneration, was regulated by various functional molecules. In recent years, a growing body of research has shown that miRNAs play a crucial role in the odontogenic differentiation of human dental pulp stem cells (hDPSCs). However, the mechanisms by which miRNAs regulated odontogenic differentiation of hDPSCs remained unclear, and the application of miRNAs in reparative dentin formation in vivo was also rare. In this study, we first discovered that miR-3074-3p had an inhibitory effect on odontogenic differentiation of hDPSCs and antagomiR-3074-3p-conjugated PEI-AuNPs effectively promoted odontogenic differentiation of hDPSCs in vitro. AntagomiR-3074-3p-conjugated PEI-AuNPs was further applied to the rat pulp-capping model and showed the increased formation of restorative dentin. In addition, the results of lentivirus transfection in vitro suggested that FKBP9 acted as the key target of miR-3074-3p in regulating the odontogenic differentiation of hDPSCs. These findings might provide a new strategy and candidate target for dentin restoration and tooth regeneration. [ABSTRACT FROM AUTHOR]

Background: Human dental pulp stem cells (hDPSCs) may be the best choice for self-repair and regeneration of teeth and maxillofacial bone tissue due to their homogeneous tissue origin, high proliferation and differentiation rates, and no obvious ethical restrictions. Recently, several studies have shown that extracellular matrix (ECM) proteins can effectively regulate the proliferation and differentiation fate of mesenchymal stem cells (MSCs). However, the role of elastin microfibril interface-located protein-1 (EMILIN-1), a new ECM glycoprotein, in osteo/odontogenic differentiation of hDPSCs has not been reported. The aim of this study was to explore the effect of EMILIN-1 during osteo/odontogenic differentiation of hDPSCs. Methods: hDPSCs were cultured in osteo/odontogenic induction medium. qPCR and Western blot analysis were performed to detect osteo/odonto-specific genes/proteins expression as well as the expression of EMILIN-1. After knockdown of Emilin-1 in hDPSCs with small interfering RNA and exogenous addition of recombinant human EMILIN-1 protein (rhEMILIN-1), Cell Counting Kit-8 assay, alkaline phosphatase staining, alizarin red S staining, qPCR and Western blot were performed to examine the effect of EMILIN-1 on proliferation and osteo/odontogenic differentiation of hDPSCs. Results: During the osteo/odontogenic induction of hDPSCs, the expression of osteo/odonto-specific genes/proteins increased, as did EMILIN-1 protein levels. More notably, knockdown of Emilin-1 decreased hDPSCs proliferation and osteo/odontogenic differentiation, whereas exogenous addition of rhEMILIN-1 increased them. Conclusions: These findings suggested that EMILIN-1 is essential for the osteo/odontogenic differentiation of hDPSCs, which may provide new insights for teeth and bone tissue regeneration. [ABSTRACT FROM AUTHOR]

Tooth is a vital organ in the oral cavity that has functions for chewing, talking, swallowing, and giving facial aesthetics. Tooth decay or loss can reduce the quality of life (QOL). Nowadays, tooth decay treatment is restored through a conservative approach, which uses dental inorganic materials and their supporting tools. Besides, the loss of a tooth can be replaced by a dental prosthetic or artificial tooth. The advanced and greatly promising technology in the future is to apply the concept of regenerative dentistry as a biological repair of lost and damaged tissue using stem cells. Regenerative medicine using stem cells is promising therapeutic tool in the future to restore or replace the damage tissue into normal function by utilized their potency to differentiate into specialized cells type. This review aims to report the potential of stem cells for tooth regeneration and tissue repair in dental field. [ABSTRACT FROM AUTHOR]

Tooth defects are an extremely common health condition that affects millions of individuals. Currently used dental repair treatments include fillings for caries, endodontic treatment for pulp necrosis, and dental implants to replace missing teeth, all of which rely on the use of synthetic materials. By contrast, the fields of tissue engineering and regenerative medicine and dentistry (TERMD) use biologically based therapeutic strategies for vital tissue regeneration, and thus have the potential to regenerate living tissues. Methods to create bioengineered replacement teeth benefit from a detailed understanding of the molecular signaling networks regulating natural tooth development. We discuss how key signaling pathways regulating natural tooth development are being exploited for applications in TERMD approaches for vital tooth regeneration. The importance of oral health, and its essential link to systemic health, is a serious health concern worldwide. Current therapies used to repair craniomaxillofacial (CMF) defects largely rely on the use of synthetic materials that lack many essential features of natural CMF tissues. The ability to regenerate living, hard and soft dental tissues to repair dental tissues damaged by disease, trauma, genetic, and other disorders would be a significant improvement over the currently used methods. Recent progress in the TERMD field has helped to devise more effective methods to regenerate vital dental tissues. Novel TERMD therapies are anticipated to significantly improve our ability to effectively repair CMF tissues. These new therapies are anticipated to have a significant impact on the dental therapeutics market. [ABSTRACT FROM AUTHOR]

Oral organoids are complex 3-dimensional structures that develop from stem cells or organ-specific progenitors through a process of self-organization and re-create architectures and functionalities similar to in vivo organs and tissues in the oral and maxillofacial region. Recently, striking advancements have been made in the construction and application of oral organoids of the tooth, salivary gland, and tongue. Dental epithelial and mesenchymal cells isolated from tooth germs or derived from pluripotent stem cells could generate tooth germ–like organoids by self-organization in a specific culture system. Tooth organoids can also be constructed based on tissue engineering principles by seeding stem cells on a scaffold with the bioregulatory functions of odontogenic differentiation. Two main approaches have been used to construct salivary gland organoids: 1) incubation of salivary gland–derived stem/progenitor cells in a 3-dimensional culture system to form the structure of the gland through mimicking regenerative processes and 2) inducing of pluripotent stem cells to generate embryonic salivary glands by replicating the development process. Taste bud organoids can be generated by embedding isolated circumvallate papilla tissue in Matrigel with a mixture of growth factors, while lingual epithelial organoids have been constructed using lingual stem cells in a suitable culture system containing specific signaling molecules. These oral organoids usually maintain the main functions and characteristic structures of the corresponding organ to a certain extent. Furthermore, using cells isolated from patients, oral organoids could replicate specific diseases such as maxillofacial tumors and tooth dysplasia. Until now, oral organoids have been applied in the study of mechanisms of tooth development, pathology and regeneration of the salivary gland, and precision therapeutics for tongue cancer. These findings strongly demonstrate that the organoid technique is a novel paradigm for the study of the development, pathology, and regeneration of oral and maxillofacial tissue. [ABSTRACT FROM AUTHOR]

Regenerating the periodontal ligament (PDL) is a crucial factor for periodontal tissue regeneration in the presence of traumatized and periodontally damaged teeth. Various methods have been applied for periodontal regeneration, including tissue substitutes, bioactive materials, and synthetic scaffolds. However, all of these treatments have had limited success in structural and functional periodontal tissue regeneration. To achieve the goal of complete periodontal regeneration, many studies have evaluated the effectiveness of decellularized scaffolds fabricated via tissue engineering. The aim of this study was to fabricate a decellularized periodontal scaffold of human tooth slices and determine its regeneration potential. We evaluated two different protocols applied to tooth slices obtained from human healthy third molars. The extracellular matrix scaffold decellularized using sodium dodecyl sulfate and Triton X-100, which are effective in removing nuclear components, was demonstrated to preserve an intact structure and composition. Furthermore, the decellularized scaffold could support repopulation of PDL stem cells near the cementum and expressed cementum and periodontal-ligament-related genes. These results show that decellularized PDL scaffolds of human teeth are capable of inducing the proliferation and differentiation of mesenchymal stem cells, thus having regeneration potential for use in future periodontal regenerative tissue engineering. [ABSTRACT FROM AUTHOR]

Stem cells are undifferentiated cells that can differentiate into specialized cells. Recently, enormous growth has been seen in the recognition of stem cell-based therapies, which have the potential to ameliorate the life of patients with conditions that span from Parkinson's disease to cardiac ischemia to bone or tooth loss. This research has produced new but unexplored possibilities in the regeneration of different organs and tissues. Presently, research is focused on the proficiency of stem cells and their utilization in dentistry, which is gaining interest. The tooth is nature's “esteem” for these precious stem cells and there are a number of these cells in permanent and primary teeth, as well as in the wisdom teeth. Dental stem cells are easy, convenient, and affordable to collect. They hold promise for a range of very potential therapeutic applications, such as in the treatment of cancer, spinal cord injury, brain damage, myocardial infarction, hearing loss, diabetes, wound healing, baldness, etc. Since these cells were used to regenerate damaged tissue in medical therapy successfully, it is possible that the dentist in future might use stem cell to regenerate lost or damaged dental and periodontal structures. This paper reviews the current concepts, characteristics of stem cells in regeneration, and its subsequent uses in dentistry.

Over the last several decades, a wealth of information has become available regarding various sources of stem cells and their potential use for regenerative purposes. Given the intense debate regarding embryonic stem cells, much of the focus has centered around application of adult stem cells for regenerative engineering along with other relevant aspects including use of growth factors and scaffolding materials. The more recent discovery of tooth-derived stem cells has sparked much interest in their application to regenerative dentistry to treat and alleviate the most prevalent oral diseases—i.e., dental caries and periodontal diseases. Also exciting is the advent of induced pluripotent stem cells, which provides the means of using patient-derived somatic cells for their creation, and their eventual application for generation of the dental complex. Thus, evolving developments in the field of regenerative dentistry indicate the prospect of constructing "custom-made" tooth and supporting structures thereby fostering the realization of "personalized dentistry." On the other hand, others have explored the possibility of augmenting endogenous regenerative capacity through utilization of small molecules to regulate molecular signaling mechanisms that mediate regeneration of tooth structure. This review is focused on these aspects of regenerative dentistry in view of their relevance to personalized dentistry. [ABSTRACT FROM AUTHOR]

Traumatic injuries, genetic diseases, and external harmful agents such as bacteria and acids often compromise tooth integrity. There is an unmet medical need to develop alternative, innovative dental treatments that complement traditional restorative and surgery techniques. Stem cells have transformed the medical field in recent years. The combination of stem cells with bioactive scaffolds and nanostructured materials turns out to be increasingly beneficial in regenerative dental medicine. Stem cell-based regenerative approaches for the formation of dental tissues will significantly improve treatments and will have a major impact in dental practice. To date there is no established and reliable stem cell-based treatment translated into the dental clinics, however, the advances and improved technological knowledge are promising for successful dental therapies in the near future. Here, we review some of the contemporary challenges in dental medicine and describe the benefits and future possibilities of certain novel approaches in the emerging field of regenerative dentistry. [ABSTRACT FROM AUTHOR]

Remarkable breakthroughs in the fields of developmental biology and stem cell biology during the last 15 yr have led to a new level of understanding regarding how teeth develop and how stem cells can be programmed. As a result, the possibilities of growing new teeth and of tooth bioengineering have been explored. Currently, a great deal is known about how signaling molecules and genes regulate tooth development, and modern research using transgenic mouse models has demonstrated that it is possible to induce the formation of new teeth by tinkering with the signaling networks that govern early tooth development. A breakthrough in stem cell biology in 2006 opened up the possibility that a patient′s own cells can be programmed to develop into pluripotent stem cells and used for building new tissues and organs. At present, active research in numerous laboratories around the world addresses the question of how to program the stem and progenitor cells to develop into tooth‐specific cell types. Taken together, the remarkable progress in developmental and stem cell biology is now feeding hopes of growing new teeth in the dental clinic in the not‐too‐distant future. [ABSTRACT FROM AUTHOR]

Introduction: There has been a noticeable increase in experimental use and therapies based on stem cells over recent years. Nevertheless, there is a lack of information about this progress in the dental field, which makes it difficult to trace development and design policies. The purpose of this study, as a first approach to the subject, is to determine a bibliometric profile for the investigation related to bioengineering of dental tissue at a worldwide scale, based on the MEDLINE database, for the period 2000-2011. Methodology: A bibliometric study was carried out. Every article indexed in the MEDLINE database and associated with the terms “stem cells” and “tooth regeneration” for the period 2000-2011 was included. The analyzed variables were publishing date, country of origin, language and publication type (original or review), journal, author, associated university and tissue source (human or animal). Results: For the entire period included in the study, 257 articles were found. Of these, 149 corresponded to original Works published in English; 5 in other languages; 92 comprised literature reviews in English, 9 in other languages and 2 publications were included in the “others” category. The countries with the highest research productivity were the United States (24.51%), Japan (20.62%) and China (17.90%), while Brazil (3.9%) was the only Latin-American country found in the list. Animal tissues were used in 59.09% of them. The most productive authors were Ueda M (17) and Jin Y (11), whereas Fourth Military University (13), University of Tokyo (12) and Capital Medical University (10) had the largest number of publications. Conclusion: The United States, Japan and China concentrate about two thirds of the production. Latin-America was represented only by Brazil.

Since cells isolated from the developing tooth possess an enormous regenerative potential, it has been proposed that they could be applied to the in vivo regeneration of teeth in dental practice. The generation of the entire tooth structure depends upon the developmental stage of tooth when the cells are harvested. This review focuses on the performance of postnatal and adult dental cells that have been used for generating teeth. Their ability to contribute to tooth development was assessed in the omentum or in the tooth socket. Adult dental cells were limited in their potential owing to various parameters. From these results described, new approaches for regenerated teeth are proposed in this review. One strategy to replace teeth is tooth root engineering using tissue from postnatal teeth. Since the enamel organ epithelium disappears after tooth maturation, the epithelial rest cells of Malassez were evaluated to determine their capacity to generate enamel. From these results, it is suggested that erupted mature teeth have cell sources with the capacity to produce tooth root. The development of biological approaches for tooth root regeneration using postnatal dental cells is promising and remains one of the greatest challenges in the dental field in the years to come.

Stem cells are undifferentiated cells that can differentiate into specialized cells. Recently, enormous growth has been seen in the recognition of stem cell-based therapies, which have the potential to ameliorate the life of patients with conditions that span from Parkinson's disease to cardiac ischemia to bone or tooth loss. This research has produced new but unexplored possibilities in the regeneration of different organs and tissues. Presently, research is focused on the proficiency of stem cells and their utilization in dentistry, which is gaining interest. The tooth is nature's “esteem” for these precious stem cells and there are a number of these cells in permanent and primary teeth, as well as in the wisdom teeth. Dental stem cells are easy, convenient, and affordable to collect. They hold promise for a range of very potential therapeutic applications, such as in the treatment of cancer, spinal cord injury, brain damage, myocardial infarction, hearing loss, diabetes, wound healing, baldness, etc. Since these cells were used to regenerate damaged tissue in medical therapy successfully, it is possible that the dentist in future might use stem cell to regenerate lost or damaged dental and periodontal structures. This paper reviews the current concepts, characteristics of stem cells in regeneration, and its subsequent uses in dentistry. [ABSTRACT FROM AUTHOR]

During embryonic organogenesis, the odontogenic potential resides in dental mesenchyme from the bud stage until birth. Mouse dental mesenchymal cells (mDMCs) isolated from the inductive dental mesenchyme of developing molars are frequently used in the context of tooth development and regeneration. We wondered if and how the odontogenic potential could be retained when mDMCs were cultured in vitro. In the present study, we undertook to test the odontogenic potential of cultured mDMCs and attempted to maintain the potential during culturing. We found that cultured mDMCs could retain the odontogenic potential for 24 h with a ratio of 60% for tooth formation, but mDMCs were incapable of supporting tooth formation after more than 24 h in culture. This loss of odontogenic potential was accompanied by widespread transcriptomic alteration and, specifically, the downregulation of some dental mesenchyme-specific genes, such as Pax9, Msx1, and Pdgfrα. To prolong the odontogenic potential of mDMCs in vitro, we then cultured mDMCs in a serum-free medium with Knockout Serum Replacement (KSR) and growth factors (fibroblastic growth factor 2 and epidermal growth factor). In this new micromilieu, mDMCs could maintain the odontogenic potential for 48 h with tooth formation ratio of 50%. Moreover, mDMCs cultured in KSR-supplemented medium gave rise to tooth-like structures when recombined with non-dental second-arch epithelium. Among the supplements, KSR is essential for the survival and adhesion of mDMCs, and both Egf and Fgf2 induced the expression of certain dental mesenchyme-related genes. Taken together, our results demonstrated that the transcriptomic changes responded to the alteration of odontogenic potential in cultured mDMCs and a new micromilieu partly retained this potential in vitro, providing insight into the long-term maintenance of odontogenic potential in mDMCs. [ABSTRACT FROM AUTHOR]

The breakthrough of stem cells, also known as progenitor or precursor cells, has produced new possibilities in the regeneration of different organs and tissues. Currently, studies and research work to know the latent capabilities of stem cells and their utilization in dentistry are becoming an exciting topic. Stem cell biology, an emerging field of research, provides promising methods in vitro as well as in vivo in animal models which make speculation about a future application in human dentistry reasonable. This review will help researches to update their knowledge regarding stem cells and their applications in different fields of dentistry. [ABSTRACT FROM AUTHOR]

• A novel functional biological root with a sandwich structure is constructed. • The favorable regeneration potential of FBR is proved in non-human primate over two years of implantation. • The FBR restores the "sandwich" structure of cementum-periodontal ligament-alveolar bone complex. • The FBR exhibits good biocompatibility. Stem cell/scaffold-based tissue engineering technology is expected to regenerate tooth root, thus replace dental implant. Although numerous patterns of biological tooth root have been constructed, most of them failed for the reasons involved the type of selected stem cells, scaffold materials, and the recombination strategy of cell-scaffold complexes. Here we introduced a novel functional biological root (FBR) with a sandwich structure, by which occlusal function and long-term masticatory function were gradually restored during two years functional evaluation in rhesus monkeys. FBR complex was constructed based on dental follicle cell sheets (DFCSs) and treated dentin matrix (TDM) under in vitro 3D suspension culture. Compared with other reported systems, DFCs displayed a more suitable seeding cell potential for bio-root construction due to the eminent odontogenic potential to develop cementum, periodontal ligament, and alveolar bone in vivo. Meanwhile, TDM also exhibited unique superiority of reserving native dentin tubules which can release numerous odontogenic proteins and factors comparing with other materials. Another unique characteristic of this work was that the favorable regeneration potential of FBR was proved in non-human primate, whose tooth morphology, number and development was more similar to humans, and the resulting FBRs closely resembled the natural tooth root in terms of their anatomical and physiological features, especially the "sandwich" structure of periodontal tissue, adequately demonstrating its potential application in tooth root regeneration. [ABSTRACT FROM AUTHOR]

Stem cells are capable of renewing themselves through cell division and have the remarkable ability to differentiate into many different types of cells. They therefore have the potential to become a central tool in regenerative medicine. During the last decade, advances in tissue engineering and stem cell-based tooth regeneration have provided realistic and attractive means of replacing lost or damaged teeth. Investigation of embryonic and adult (tissue) stem cells as potential cell sources for tooth regeneration has led to many promising results. However, technical and ethical issues have hindered the availability of these cells for clinical application. The recent discovery of induced pluripotent stem (iPS) cells has provided the possibility to revolutionize the field of regenerative medicine (dentistry) by offering the option of autologous transplantation. In this article, we review the current progress in the field of stem cell-based tooth regeneration and discuss the possibility of using iPS cells for this purpose.

Tooth loss is universal. Its many causes include physical trauma, gingival and periodontal disease, dental caries and genetic de-fects. The resultant migration of adjacent and opposing teeth into the space, difficulties in mastication and esthetic problems are indeed major issues to be taken care of. Currently, several approaches based on non-biological techniques such as dentures, cro-wns and implants are in vogue, with latter relying heavily on various parameters like bone thickness, density and osseo-integr-ation. On the other hand a biological approach for developing dental structures in the laboratory involves the manipulation of both epithelial and mesenchymal stem cells for bringing about tooth initiation, enamel matrix and dentin formation (in-vitro) respectively. Use of stem cells remains a promising yet challenging approach since its application in dental practice is compli-cated owing to numerous parameters which are not under control such as the high risk of rejection, cell behavior, long tooth eruption period, appropriate crown morphology and suitable colour. [ABSTRACT FROM AUTHOR]

A tooth is a complex biological organ and consists of multiple tissues including the enamel, dentin, cementum and pulp. Tooth loss is the most common organ failure. Can a tooth be regenerated? Can adult stem cells be orchestrated to regenerate tooth structures such as the enamel, dentin, cementum and dental pulp, or even an entire tooth? If not, what are the therapeutically viable sources of stem cells for tooth regeneration? Do stem cells necessarily need to be taken out of the body, and manipulated ex vivo before they are transplanted for tooth regeneration? How can regenerated teeth be economically competitive with dental implants? Would it be possible to make regenerated teeth affordable by a large segment of the population worldwide? This review article explores existing and visionary approaches that address some of the above-mentioned questions. Tooth regeneration represents a revolution in stomatology as a shift in the paradigm from repair to regeneration: repair is by metal or artificial materials whereas regeneration is by biological restoration. Tooth regeneration is an extension of the concepts in the broad field of regenerative medicine to restore a tissue defect to its original form and function by biological substitutes. [ABSTRACT FROM AUTHOR]

Abstract: Rodent incisors provide a classic model for studying epithelial–mesenchymal interactions in development. However, postnatal stem/progenitor cells in rodent incisors have not been exploited for tooth regeneration. Here, we characterized postnatal rat incisor epithelium and mesenchyme stem/progenitor cells and found that they formed enamel- and dentin-like tissues in vivo. Epithelium and mesenchyme cells were harvested separately from the apical region of postnatal 4–5 day rat incisors. Epithelial and mesenchymal phenotypes were confirmed by immunocytochemistry, CFU assay and/or multi-lineage differentiation. CK14+, Sox2+ and Lgr5+ epithelium stem cells from the cervical loop enhanced amelogenin and ameloblastin expression upon BMP4 or FGF3 stimulation, signifying their differentiation towards ameloblast-like cells, whereas mesenchyme stem/progenitor cells upon BMP4, BMP7 and Wnt3a treatment robustly expressed Dspp, a hallmark of odontoblastic differentiation. We then control-released microencapsulated BMP4, BMP7 and Wnt3a in transplants of epithelium and mesenchyme stem/progenitor cells in the renal capsule of athymic mice in vivo. Enamel and dentin-like tissues were generated in two integrated layers with specific expression of amelogenin and ameloblastin in the newly formed, de novo enamel-like tissue, and DSP in dentin-like tissue. These findings suggest that postnatal epithelium and mesenchyme stem/progenitor cells can be primed towards bioengineered tooth regeneration. [Copyright &y& Elsevier]

Pulp regeneration using human dental pulp stem cells (hDPSCs) maintains tooth vitality compared with conventional root canal therapy. Our previous study demonstrated that preameloblast-conditioned medium (PA-CM) from murine apical bud cells induces the odontogenic differentiation of hDPSCs and promoted dentin formation in mouse subcutaneous tissue. The purpose of the present study is to evaluate the effects of PA-CM with human whole pulp cells on pulp regeneration in an empty root canal space. Human pulp cells were seeded in the pulp cavities of 5 mm-thick human tooth segments with or without PA-CM treatment, and then transplanted subcutaneously into immunocompromised mice. In the pulp cell-only group, skeletal muscle with pulp-like tissue was generated in the pulp cavity. A reparative dentin-like structure with entrapped cells lined the existing dentin wall. However, in the PA-CM-treated group, only pulp-like tissue was regenerated without muscle or a reparative dentin-like structure. Moreover, human odontoblast-like cells exhibited palisade arrangement around the pulp, and typical odontoblast processes elongated into dentinal tubules. The results suggest that PA-CM can induce pulp regeneration of human pulp cells with physiological structures in an empty root canal space. [ABSTRACT FROM AUTHOR]

Aims and objectives: Isolation, characterization and differentiation of dental pulp stem cells (DPSCs) and stem cells from exfoliated human deciduous teeth (SHED). Methods: The pulp tissue was digested in collagenase and cultured in DMEM Dulbecco's Modified Eagle's Media). The stem cells were identified and isolated. Surface characterization of cells was done with flow cytometer using surface markers. An immuno cytochemistry analysis was done. Differentiation potential was analyzed using various differentiation markers. Results: Flow cytometry analyses for various CD markers showed similar results for both DPSCs and SHED. The cells showed positive expression for pluripotent, ectodermal and mesodermal markers. Cells differentiated into osteoblasts and adipocytes. Conclusion: The study demonstrated that stem cells existed in deciduous and permanent pulp tissue. The stem cells present in pulp tissue can be isolated, cultivated and expanded in vitro. Both DPSCs and SHED show almost a similar expression pattern profile for variety of antigens tested. [ABSTRACT FROM AUTHOR]

Abstract: New technologies that facilitate solid alveolar ridge augmentation are receiving considerable attention in the field of prosthodontics because of the growing requirement for esthetic and functional reconstruction by dental implant treatments. Recently, several studies have demonstrated potential advantages for stem-cell-based therapies in regenerative treatments. Mesenchymal stem/stromal cells (MSCs) are now an excellent candidate for tissue replacement therapies, and tissue engineering approaches and chair-side cellular grafting approaches using autologous MSCs represent the clinical state of the art for stem-cell-based alveolar bone regeneration. Basic studies have revealed that crosstalk between implanted donor cells and recipient immune cells plays a key role in determining clinical success that may involve the recently observed immunomodulatory properties of MSCs. Part II of this review first overviews progress in regenerative dentistry to consider the implications of the stem cell technology in dentistry and then highlights cutting-edge stem-cell-based alveolar bone regenerative therapies. Factors that affect stem-cell-based bone regeneration as related to the local immune response are then discussed. Additionally, pre-clinical stem cell studies for the regeneration of teeth and other oral organs as well as possible applications of MSC-based immunotherapy in dentistry are outlined. Finally, the marketing of stem cell technology in dental stem cell banks with a view toward future regenerative therapies is introduced. [Copyright &y& Elsevier]

The generation of dental structures and/or entire teeth in the laboratory depends upon the manipulation of stem cells and requires a synergy of all cellular and molecular events that finally lead to the formation of tooth-specific hard tissues, dentin and enamel. This review focuses on the different sources of stem cells that have been used for making teeth in vitro and their relative efficiency. Embryonic, post-natal and adult stem cells were assessed and proved to possess an enormous regenerative potential, but their application in dental practice is still limited due to various parameters that are not yet under control such as the high risk of rejection, cell behaviour, long tooth eruption period, appropriate crown morphology and suitable colour. Nevertheless, the development of biological approaches for dental reconstruction using stem cells is promising and remains one of the greatest challenges in the dental field. [ABSTRACT FROM AUTHOR]

Multipotent mesenchymal stem cells from bone marrow are expected to be a somatic stem cell source for the development of new cell-based therapy in regenerative medicine. However, dental clinicians are unlikely to carry out autologous cell/tissue collection from patients (i.e., marrow aspiration) as a routine procedure in their clinics; hence, the utilization of bone marrow stem cells seems impractical in the dental field. Dental tissues harvested from extracted human teeth are well known to contain highly proliferative and multipotent stem cell compartments and are considered to be an alternative autologous cell source in cell-based medicine. This article provides a short overview of the ongoing studies for the potential application of dental stem cells and suggests the utilization of 2 concepts in future regenerative medicine: (1) dental stem cell-based therapy for hepatic and other systemic diseases and (2) tooth replacement therapy using the bioengineered human whole tooth, called the 'test-tube dental implant.' Regenerative therapies will bring new insights and benefits to the fields of clinical medicine and dentistry. [ABSTRACT FROM AUTHOR]

Tooth regeneration by cell delivery encounters translational hurdles. We hypothesized that anatomically correct teeth can regenerate in scaffolds without cell transplantation. Novel, anatomically shaped human molar scaffolds and rat incisor scaffolds were fabricated by 3D bioprinting from a hybrid of poly-?-caprolactone and hydroxyapatite with 200-?m-diameter interconnecting microchannels. In each of 22 rats, an incisor scaffold was implanted orthotopically following mandibular incisor extraction, whereas a human molar scaffold was implanted ectopically into the dorsum. Stromal-derived factor-1 (SDF1) and bone morphogenetic protein-7 (BMP7) were delivered in scaffold microchannels. After 9 weeks, a putative periodontal ligament and new bone regenerated atthe interface of rat incisor scaffold with native alveolar bone. SDF1 and BMP7 delivery not only recruited significantly more endogenous cells, but also elaborated greater angiogenesis than growthfactor-free control scaffolds. Regeneration of tooth-like structures and periodontal integration by cell homing provide an alternative to cell delivery, and may accelerate clinical applications. [ABSTRACT FROM AUTHOR]

Summary: Since cells isolated from the developing tooth possess an enormous regenerative potential, it has been proposed that they could be applied to the in vivo regeneration of teeth in dental practice. The generation of the entire tooth structure depends upon the developmental stage of tooth when the cells are harvested. This review focuses on the performance of postnatal and adult dental cells that have been used for generating teeth. Their ability to contribute to tooth development was assessed in the omentum or in the tooth socket. Adult dental cells were limited in their potential owing to various parameters. From these results described, new approaches for regenerated teeth are proposed in this review. One strategy to replace teeth is tooth root engineering using tissue from postnatal teeth. Since the enamel organ epithelium disappears after tooth maturation, the epithelial rest cells of Malassez were evaluated to determine their capacity to generate enamel. From these results, it is suggested that erupted mature teeth have cell sources with the capacity to produce tooth root. The development of biological approaches for tooth root regeneration using postnatal dental cells is promising and remains one of the greatest challenges in the dental field in the years to come. [Copyright &y& Elsevier]

The human innate regenerative ability is known to be limited by the intensity of the insult together with the availability of progenitor cells, which may cause certain irreparable damage. It is only recently that the paradigm of tissue engineering found its way to the treatment of irreversibly affected body structures with the challenge of reconstructing the lost part. In the current review, we underline recent trials that target engineering of human craniofacial structures, mainly bone, cartilage, and teeth. We analyze the applied engineering strategies relative to the selection of cell types to lay down a specific targeted tissue, together with their association with an escorting scaffold for a particular engineered site, and discuss their necessity to be sustained by growth factors. Challenges and expectations for facial skeletal engineering are discussed in the context of future treatment. [ABSTRACT FROM AUTHOR]