OSTEOGENIC MECHANISMS OF SHED

描述(申请人提供)：本申请的目的是了解人类脱落乳牙(SHOLD)干细胞的成骨机制，作为开发修复口腔面骨缺损的治疗技术的基础。通常用于修复口腔颌面部骨缺损的自体长骨移植往往会导致不良的结果，部分原因可能是口腔颌面和长骨分别起源于神经脊细胞和中胚层，而口腔颌面部间充质干细胞与长骨间充质干细胞具有明显的分化特性。在此之前，我们已经证明SHEAD能够分化为成牙本质细胞、脂肪细胞和神经细胞。然而，Share最明显的特征之一是其移植到免疫低下小鼠体内时具有很强的成骨能力。我们的初步研究表明，SHIP可用于修复小鼠临界大小的顶骨缺损，为口腔颌面部骨再生提供了一种有吸引力的干细胞来源。有趣的是，我们的初步研究还表明，Share的基因表达谱与骨髓间充质干细胞(BMMSCs)的基因表达谱不同，这与BMMSC移植中看到的Share生成的骨结构缺乏相关的骨髓元素这一事实相对应。我们的假设是，来源于神经脊细胞的SHIP具有独特的成骨特性，可能是修复口腔颌面部骨缺损的最佳干细胞来源。在这项应用中，我们将检查根据其表面分子纯化的棚子亚群是否显示出优越的分化和组织再生能力。我们将描述Share独特的成骨特性，例如BMP-2和bFGF如何调控Share介导的成骨。根据我们关于端粒酶维持BMMSCs功能的新发现，我们研究了如何利用生长因子激活Share中的端粒酶活性来提高其组织再生能力。最后，我们开发了扩大小型猪舍的最佳条件，并利用它们进行自体移植以修复顶骨缺陷，这是在进行人体棚子试验之前检查任何有效性和潜在挑战的必要的临床前步骤。总之，我们建议的研究中的新发现将为理解脱落介导的骨形成提供分子基础，并对口腔颌面部骨再生产生重要影响。

DESCRIPTION (provided by applicant): The objective of this application is to understand osteogenic mechanisms of stem cells from human exfoliated deciduous teeth (SHED) as a basis for the development of therapeutic technologies for repairing orofacial bone defects. Autologous grafts from long bones that are commonly used to repair orofacial bone defects often result in unfavorable outcomes, which may be due, in part, to the fact that orofacial and long bones originate from neural crest cells and mesoderm, respectively, and orofacial mesenchymal stem cells show a distinctive differentiation trait from long bone mesenchymal stem cells. Previously, we showed that SHED are capable of differentiating into odontoblasts, adipocytes, and neural cells. However, one of the most distinct characteristics of SHED is their strong osteogenic capacity when transplanted into immunocompromised mice. Our preliminary studies demonstrated that SHED could be utilized to repair critical-size parietal defects in mice, offering an attractive stem cell resource for orofacial bone regeneration. Interestingly, our preliminary studies showed also that SHED has a gene expression profile distinct from that of bone marrow mesenchymal stem cells (BMMSCs), which correspond to the fact that SHED-generated bone structure lacks associated bone marrow elements, as seen in BMMSC transplants. Our hypothesis is that SHED, derived from neural crest cells, possesses a unique osteogenic trait and may be an optimal stem cell resource for repairing orofacial bone defects. In this application, we will examine whether a sub-population of SHED purified according to their surface molecules show superior differentiation and tissue regeneration capacities. We will characterize the distinctive osteogenic trait of SHED, such as how BMP-2 and bFGF regulate SHED-mediated osteogenesis. On the basis of our novel findings on the maintenance of BMMSCs function by telomerase, we examine how to use growth factors to activate telomerase activity in SHED for improving their tissue regeneration capacity. Finally, we develop optimal conditions to expand minipig SHED and utilize them for autologous transplantation to repair parietal defects, which is a necessary pre-clinical step to examine any efficacy and potential challenges before conducting a human SHED trial. Collectively, novel findings from our proposed studies will provide a molecular basis for understanding SHED-mediated bone formation and have important impacts in orofacial bone regeneration.