OSTEOGENIC MECHANISMS OF SHED

描述（由申请人提供）：本申请的目的是了解来自人脱落乳牙（SHED）的干细胞的成骨机制，作为开发修复口面骨缺损的治疗技术的基础。通常用于修复口面骨缺损的长骨自体移植物通常导致不利的结果，这可能部分是由于口面骨和长骨分别来源于神经嵴细胞和中胚层，并且口面间充质干细胞显示出与长骨间充质干细胞不同的分化特征。以前，我们发现SHED能够分化为成牙本质细胞、脂肪细胞和神经细胞。然而，SHED最显著的特征之一是当移植到免疫受损小鼠时其强大的成骨能力。我们的初步研究表明，SHED可用于修复小鼠顶骨缺损的临界大小，为口面骨再生提供了一个有吸引力的干细胞资源。有趣的是，我们的初步研究还表明，SHED具有与骨髓间充质干细胞（BMMSC）不同的基因表达谱，这对应于SHED产生的骨结构缺乏相关骨髓元素的事实，如在BMMSC移植中所见。我们的假设是，SHED，来源于神经嵴细胞，具有独特的成骨特性，可能是修复口面部骨缺损的最佳干细胞资源。在本申请中，我们将检查根据其表面分子纯化的SHED亚群是否显示出上级分化和组织再生能力。我们将描述SHED独特的成骨特性，如BMP-2和bFGF如何调节SHED介导的成骨。基于我们对端粒酶维持BMMSCs功能的新发现，我们研究了如何使用生长因子激活SHED中的端粒酶活性以提高其组织再生能力。最后，我们开发了扩大小型猪SHED的最佳条件，并利用它们进行自体移植以修复顶骨缺陷，这是在进行人类SHED试验之前检查任何疗效和潜在挑战的必要临床前步骤。总的来说，我们提出的研究的新发现将为理解SHED介导的骨形成提供分子基础，并对口面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.