Human Hertwig's epithelial root sheath cells play crucial roles in cementum formation

Hertwig's epithelial root sheath (HERS) cells are a unique population of epithelial cells in the periodontal ligament compartment. To date, their functional role has not been fully elucidated. Our hypothesis was that HERS cells may be involved in regulating differentiation of periodontal ligament stem cells (PDLSCs) and forming cementum in vivo. In this study, we found that HERS cells may be capable of promoting PDLSC differentiation and undergoing epithelial-mesenchymal transition in vitro. Immunohistochemical staining, Western blot analysis, a transwell co-culture system, and in vivo transplantation were used to characterize the interplay between HERS cells and PDLSCs, as well as the epithelial-mesenchymal transition (EMT) of HERS cells. TGFbeta1 was capable of inducing the epithelial-mesenchymal transition of HERS cells through activating the PI3K/AKT pathway. Furthermore, HERS cells were able to form cementum-like tissue when transplanted into immunocompromised mice. Abbreviations: bone marrow mesenchymal stem cell, BMMSC; bone sialoprotein, BSP; hydroxyapatite/tricalcium phosphate, HA/TCP; Hertwig's epithelial root sheath, HERS; osteocalcin, OCN; periodontal ligament, PDL; periodontal ligament stem cell, PDLSC; phosphatidylinositol 3-kinase, PI3K.     

Allogeneic Stem Cells From Deciduous Teeth in Treatment for Periodontitis in Miniature Swine

Background: Regeneration of lost periodontium in periodontitis is a challenge in that alveolar bone, cementum, and periodontal ligament need to be restored to their original architecture. Stem cells from exfoliated deciduous teeth (SHEDs) appear to be an attractive candidate for periodontium tissue regeneration. Previously, the authors successfully regenerated periodontal defects using autologous and allogeneic periodontal ligament stem cells (PDLSCs). The purpose of the present study is to investigate the ability of allogeneic SHEDs to regenerate lost periodontium in a swine periodontitis model. Methods: Animal models of periodontitis were established in miniature pigs, and allogeneic stem cells were isolated from miniature pig deciduous teeth (SPDs). The animal models were treated with SPDs plus hydroxyapatite/tricalcium phosphate (HA/TCP). Allogeneic PDLSCs plus HA/TCP or HA/TCP alone were set as positive control or control, respectively. Clinical assessments, computed tomography (CT) scanning, and histologic examination were used to evaluate the outcome of tissue regeneration. Results: Clinical indices including probing depth, gingival recession, and attachment loss showed significant restoration in the SPD and PDLSC treatment groups, compared to the HA/TCP group 12 weeks post‐transplantation. Meanwhile, CT scans showed that 75% of the samples had successful hard‐tissue regeneration in both PDLSC and SPD groups, compared to the HA/TCP group, where the success rate was only 25%. In addition, histologic examination demonstrated that SPD and PDLSC treatment brought about remarkable regeneration of periodontal tissues, whereas periodontal regeneration was rare in the HA/TCP group. Conclusions: Allogeneic SPDs can effectively repair hard and soft tissue loss brought about by periodontitis in a swine model. Allogeneic SHEDs, which are easily accessible, may be applied to treat periodontitis in clinics in the future.     

Differentiation of stem cells from human deciduous and permanent teeth into spiral ganglion neuron-like cells

ObjectiveStem cells from pulp tissue are a promising cell-based therapy for neurodegenerative patients based on their origin in the neural crest. The aim of this study was to differentiate and evaluate the ability of human dental pulp stem cells from permanent teeth (DPSC) and stem cells from human exfoliated deciduous teeth (SHED) to differentiate into spiral ganglion neurons.DesignAfter isolation and characterization of mesenchymal stem cell properties, DPSC and SHED were treated with the neurotrophins brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and glial cell-derived neurotrophic factor (GDNF). The differentiation was identified by immunostaining and qRT-PCR analysis of neuronal markers and measuring intracellular calcium activity.ResultsAfter 2 weeks of induction, morphological changes were observed in both DPSC and SHED. The differentiated cells expressed neuron-specific class III beta-tubulin, GATA binding protein 3 (GATA3) and tropomyosin receptor kinase B, protein markers of spiral ganglion neurons. These cells also showed upregulation of the genes encoding these proteins, namely GATA3 and neurotrophic receptor tyrosine kinase 2. Intracellular calcium dynamics that reflect neurotransmitter release were observed in differentiated DPSC and SHED.ConclusionThese results demonstrate that dental pulp stem cells from permanent and deciduous teeth can differentiate into spiral ganglion neuron-like cells.     

改良法分离培养人牙周膜干细胞

目的 改良法体外分离培养人牙周膜干细胞(PDLSC),并进行鉴定.方法采用酶消化组织块法获得人牙周膜细胞,通过有限稀释法克隆化培养、分离得到PDLSC,用含10%FBS的α-MEM培养液培养并传代:测定克隆形成率:免疫组织化学检测角蛋白及波形蛋白表达:流式细胞术分析细胞周期及表面标志物STRO-1、CD146的表达;并...     

人乳牙牙髓干细胞和恒牙牙髓干细胞的蛋白质组学比较

目的 采用蛋白质组学方法研究人乳牙牙髓干细胞（SHED）和恒牙牙髓干细胞（DPSC）中的蛋白表达差异.方法 应用双向凝胶电泳技术分离SHED和DPSC的细胞总蛋白.通过比较两种细胞的蛋白组学图谱,确定差异表达的蛋白点,而后对差异点进行基质辅助激光解析电离飞行时间质谱分析和蛋白数据库信息检索,对差异蛋白进行功能分类.结果 建立了SHED和DPSC的蛋白质组图谱,经软件分析出45个差异蛋白点,其中26个表达上调,19个表达下调,再经质谱鉴定出48种蛋白,其生物学功能涉及细胞周期、代谢等.结论 SHED与DPSC中蛋白的差异表达体现了两种细胞在结构和功能上的异同性,为进一步研究SHED和DPSC在增殖、分化中的差异,以及牙齿相关干细胞在组织工程和再生医学研究中的应用提供参考.     

牙源性间充质干细胞诱导iPS细胞的效率与时间的研究

目的研究比较不同种牙源性间充质干细胞诱导iPS细胞的效率与时间。方法分离牙髓干细胞（DPSCs）、脱落乳牙干细胞（SHED）、牙乳头干细胞（SCAP）。应用慢病毒介导Lin28、Nanog、Oct4和Sox2因子重编程获得iPS细胞。比较在同等条件下三种细胞获得iPS细胞的克隆数与平均诱导时间。结果DPSC诱导iPS细胞的效率是0.167%,高于SHED细胞和SCAP细胞的诱导效率（0.125%,0.033%）;DPSC诱导iPS细胞的平均重编程时间是20.1d,均少于SHED细胞和SCAP细胞（23.73d,25.25d）,差异均有统计学意义。结论三种不同牙源性细胞有不同的iPS细胞诱导效率与重编程时间,牙髓干细胞有较好的诱导iPS细胞的应用潜能。     

Dental pulp tissue engineering with stem cells from exfoliated deciduous teeth

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.     

Periodontal Ligament Stem Cells: An Overview

Adult postnatal stem cells are multipotent and can be experimentally induced to differentiate into various specialized cell lineages. This has generated considerable interest in the arena of stem cell-based therapeutics. The identification of stem cells within the periodontal ligament represents a significant development in this regard. Achieving predictable periodontal regeneration has long been a challenge, and it is known that cells involved in the mechanisms of periodontal wound healing are of mesenchymal stem cell (MSC) type. Thus, periodontal ligament stem cell (PDLSC)-based therapeutics may be a step towards predictable periodontal regeneration. Additionally, PDLSC may have alternative potential applications in hard tissue and tooth engineering. PDLSC may be isolated, grown under tissue culture conditions, expanded, optionally genetically modified and then collected and transplanted. This paper aims to overview the current knowledge, recent developments and methodology regarding PDLSC-based applications.     

Clinical utility of stem cells for periodontal regeneration

The aim of this review is to discuss the clinical utility of stem cells in periodontal regeneration by reviewing relevant literature that assesses the periodontal-regenerative potential of stem cells. We considered and described the main stem cell populations that have been utilized with regard to periodontal regeneration, including bone marrow-derived mesenchymal stem cells and the main dental-derived mesenchymal stem cell populations: periodontal ligament stem cells, dental pulp stem cells, stem cells from human exfoliated deciduous teeth, stem cells from apical papilla and dental follicle precursor cells. Research into the use of stem cells for tissue regeneration has the potential to significantly influence periodontal treatment strategies in the future.     

Dental stem cells and their sources

The search for more accessible mesenchymal stem cells than those found in bone marrow has propelled interest in dental tissues. Human dental stem/progenitor cells (collectively termed dental stem cells [DSCs]) that have been isolated and characterized include dental pulp stem cells, stem cells from exfoliated deciduous teeth, stem cells from apical papilla, periodontal ligament stem cells, and dental follicle progenitor cells. Common characteristics of these cell populations are the capacity for self-renewal and the ability to differentiate into multiple lineages. In?vitro and animal studies have shown that DSCs can differentiate into osseous, odontogenic, adipose, endothelial, and neural-like tissues.     

Evaluation of the Apical Complex and the Coronal Pulp as a Stem Cell Source for Dentin-pulp Regeneration

IntroductionThis study compared the stemness and differentiation potential of stem cells derived from the apical complex (apical complex cells [ACCs]) and coronal pulp (dental pulp stem cells [DPSCs]) of human immature permanent teeth with the aim of determining a more suitable source of stem cells for regeneration of the dentin-pulp complex.MethodsACC and DPSC cultures were established from 13 human immature permanent teeth using the outgrowth method. The proliferation capacity and colony-forming ability of ACCs and DPSCs were evaluated. ACCs and DPSCs were analyzed for mesenchymal stem cell markers using flow cytometry. The adipogenic and osteogenic differentiation potential of ACCs and DPSCs were evaluated using the quantitative real-time polymerase chain reaction and histochemical staining. ACCs and DPSCs were transplanted subcutaneously in immunocompromised mice using macroporous biphasic calcium phosphate as a carrier. The histomorphologic characteristics of the newly formed tissues were verified using hematoxylin-eosin staining and immunohistochemical staining. Quantitative alkaline phosphatase analysis and quantitative real-time polymerase chain reaction using BSP, DSPP, POSTN, and Col XII were performed.ResultsACCs and DPSCs showed similar cell proliferation potential and colony-forming ability. The percentage of mesenchymal stem cell markers was similar between ACCs and DPSCs. In the in vitro study, ACCs and DPSCs showed adipogenic and osteogenic differentiation potential. In the in vivo study, ACCs and DPSCs formed amorphous hard tissue using macroporous biphasic calcium phosphate particles. The quantity and histomorphologic characteristics of the amorphous hard tissue were similar in the ACC and DPSC groups. Formation of periodontal ligament–like tissue, positive to Col XII, was observed in ACC transplants, which was absent in DPSC transplants.ConclusionsACCs and DPSCs showed similar stemness, proliferation rate, and hard tissue–forming capacity. The notable difference was the periodontal ligament–like fiber-forming capacity of ACCs, which indicates the presence of various lineages of stem cells in the apical complex compared with the coronal pulp. Regarding regeneration of the dentin-pulp complex, the coronal pulp can be a suitable source of stem cells considering its homogenous lineages of cells and favorable osteo/odontogenic differentiation potential.     

Dental stem cells and their promising role in neural regeneration: an update

Introduction

Stem cell-based therapies are considered to be a promising treatment method for several clinical conditions such as Alzheimer's disease, Parkinson's disease, spinal cord injury, and many others. However, the ideal stem cell type for stem cell-based therapy remains to be elucidated.

Discussion

Stem cells are present in a variety of tissues in the embryonic and adult human body. Both embryonic and adult stem cells have their advantages and disadvantages concerning the isolation method, ethical issues, or differentiation potential. The most described adult stem cell population is the mesenchymal stem cells due to their multi-lineage (trans)differentiation potential, high proliferative capacity, and promising therapeutic values. Recently, five different cell populations with mesenchymal stem cell characteristics were identified in dental tissues: dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, dental follicle precursor cells, and stem cells from apical papilla.

Conclusion

Each dental stem cell population possesses specific characteristics and advantages which will be summarized in this review. Furthermore, the neural characteristics of dental pulp stem cells and their potential role in (peripheral) neural regeneration will be discussed.     

牙源性干细胞及牙髓再生的研究进展

牙髓组织中含有细胞、血管、神经和纤维等,是一个复杂的3D结构系统。随着干细胞生物学和组织工程学的相互结合和促进,牙髓再生逐渐成为可能。牙体组织中分离出的多种干细胞,如牙髓干细胞、脱落乳牙牙髓干细胞、根尖牙乳头干细胞、牙囊干细胞等,都具有再生牙髓的潜能。文章就牙源性干细胞及以牙源性干细胞为基础的牙髓再生的研究进展做一综述。     

Stem cell‐based tooth and periodontal regeneration

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.     

Somatic stem cells for regenerative dentistry

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.     

牙周膜干细胞膜片的构建及其生物学特性的研究

目的:探讨牙周膜干细胞膜片的构建及其生物学特性.方法:采用胶原酶消化人牙周膜组织,获得牙周膜干细胞(Periodontal ligament stem cells,PDLSCs),经体外鉴定、扩增后构建PDLSCs细胞膜片,并通过倒置显微镜、HE染色、扫描电镜(SEM)对PDLSCs细胞膜片形态学进行检测.此外,细胞膜...     

Stem cell properties of human dental pulp stem cells

In this study, we characterized the self-renewal capability, multi-lineage differentiation capacity, and clonogenic efficiency of human dental pulp stem cells (DPSCs). DPSCs were capable of forming ectopic dentin and associated pulp tissue in vivo. Stromal-like cells were reestablished in culture from primary DPSC transplants and re-transplanted into immunocompromised mice to generate a dentin-pulp-like tissue, demonstrating their self-renewal capability. DPSCs were also found to be capable of differentiating into adipocytes and neural-like cells. The odontogenic potential of 12 individual single-colony-derived DPSC strains was determined. Two-thirds of the single-colony-derived DPSC strains generated abundant ectopic dentin in vivo, while only a limited amount of dentin was detected in the remaining one-third. These results indicate that single-colony-derived DPSC strains differ from each other with respect to their rate of odontogenesis. Taken together, these results demonstrate that DPSCs possess stem-cell-like qualities, including self-renewal capability and multi-lineage differentiation.     

Cell Survival within Pulp and Periodontal Constructs

The purpose of this study was to measure cell survival and degradation within tissue-engineered dental constructs. Dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PLSCs) were seeded on three types of tissue engineering scaffolds: a synthetic open-cell D,D-L,L-polylactic acid (polymer) scaffold, a bovine collagen scaffold (collagen), and a calcium phosphate bioceramic (calcium phosphate) scaffold. The dental pulp and periodontal constructs (n = 144) were maintained in cell culture for between 3 and 14 days. The cell survival and degradation within the constructs were measured using histologic criteria. The DPSC and PLSC survival was optimal in the polymer and collagen constructs but not the calcium phosphate constructs, especially over longer time periods. These in vitro results suggest that both the polymer and collagen scaffolds and the DPSCs and PLSCs can be combined to create pulp and periodontal constructs for use in future regenerative dental treatments.     

血小板裂解液对人根尖牙乳头干细胞和牙周膜干细胞体内外增殖、矿化能力的影响

目的:研究血小板裂解液(Platelet Lysate,PL)在体内外对人根尖牙乳头干细胞(SCAP)和牙周膜干细胞(PDLSCs)增殖、矿化的干预效应,以期找到PL应用于这两种细胞的最佳方式。方法:在矿化诱导培养体系中按一定体积比加入PL,分别作用于体内、外复合HA-TCP支架材料三维生长的SCAP和PDLSCs,扫描电镜(SEM)以及组织学观察细胞生长、分化情况。结果:体外三维培养模式下,PL能够促进SCAP和PDLSCs的增殖以及矿化细胞外基质的形成,并利于在支架材料上形成完整的细胞膜片(cell sheet)样结构,以上效应对于PDLSCs作用更为显著。而在体内移植模式下,经50 mL/L、10 mL/L PL培养体系预培养的SCAP能形成包含成牙本质细胞样细胞、牙本质样基质和牙髓组织的牙本质牙髓复合体样结构;而PDLSCs经50 mL/LPL干预后,可分化为成牙骨质细胞样细胞,并生成牙骨质样基质、牙周膜样组织。结论:一定体积浓度比的PL能促进SCAP和PDLSCs在体内外的增殖以及成骨、成牙本质分化。