Regulation of Skeletal progenitor cells in Osteogenesis Imperfecta

项目摘要 成骨不全症（OI）是一种先天性骨骼和口面部疾病，主要影响骨骼， 以骨愈合和修复的改变为特征。像其他骨骼疾病一样，至少有一些 OI患者的进行性骨和颅面缺损归因于人群的变化， 干/祖细胞的功能。一般来说，干细胞需要一个专门的环境来进行它们的生长。 维护和功能。然而，正常或有缺陷的胶原蛋白结构成分如何调节 骨骼干/祖细胞（SSPC）基本上是未知的。因此，本提案的目标是确定 骨干/祖细胞在OI中的体内特性和功能，并了解 异常的OI细胞外基质在骨再生的背景下改变这些干/祖细胞 和修复。我们以前的研究表明，Mx 1Cre和αSMAGFP的组合可以选择性地标记骨骼干细胞， 这些Mx 1 α SMAGFP骨膜细胞是长期再生的干细胞 负责骨膜成骨细胞的终身再生和骨修复的亚群。此外，我们的初步 研究表明，这些骨膜SSPCs是Prx 1GFP阳性的，并选择性表达KDR（VEGFR 2）。人类 原代骨膜细胞也表达具有多系分化潜能的KDR。值得注意的是， 这些KDR骨膜祖细胞在OI骨中显著减少。因此，我们假设， 异常OI基质使骨膜和骨髓SSPCs的数量和功能失调， 干/祖细胞中的相关分子变化对于进行性畸形和延迟或 骨头愈合不良。通过使用一系列OI动物模型和SSPC报告小鼠， 区别标记骨膜和骨髓SSPC亚群，结合活体成像和 最新的单细胞RNA测序技术，我们计划追求以下具体目标。在目标1中， 确定临床相关OI中骨膜和骨髓SSPC的体内特征和功能 小鼠模型。在目标2中，我们将定义调节SSPC功能的关键OI矩阵因素，并改善两者 颅面和长骨愈合。完成这项工作后，我们将获得新的生物学见解， 更好地理解在OI下差异调节SSPC的分子和细胞机制 病理生理条件。

PROJECT SUMMARY Osteogenesis Imperfecta (OI) is a congenital bone and oral-facial disorder that mainly affects bone with less well characterized alterations in bone healing and repair. Like other skeletal diseases, at least some of the progressive bone and craniofacial defects in OI patients have been attributed to changes in the populations and functions of their stem/progenitor cells. In general, stem cells require a specialized environment for their maintenance and function. Nevertheless, how normal or defective structural components of collagen regulate skeletal stem/progenitor cells (SSPCs) is essentially unknown. Therefore, the goal of this proposal is to define the in vivo characteristics and function of skeletal stem/progenitor cells in OI and to understand how an abnormal OI extracellular matrix alters these stem/progenitor cells in the context of bone regeneration and repair. We previously showed that the Mx1Cre and αSMAGFP combination can selectively label skeletal stem cells in the periosteum and that these Mx1ÈαSMAGFPÈ periosteal cells are long-term repopulating stem cell subsets responsible for lifelong regeneration of periosteal osteoblasts and bone repair. Moreover, our preliminary study revealed that these periosteal SSPCs are Prx1GFP positive and selectively express KDR (VEGFR2). Human primary periosteal cells also express KDR with multi-lineage differentiation potentials. Notably, we found that these KDRÈ periosteal progenitor cells are significantly decreased in OI bones. Hence, we hypothesize that the abnormal OI matrix deregulates the number and function of periosteal and bone marrow SSPCs and the OI- associated molecular changes in stem/progenitor cells are critical for the progressive deformity and delayed or defective healing of bones. By using a series of OI animal models and SSPC reporter mice, in which we can differentially label periosteal and bone marrow SSPC subsets, in combination with intravital imaging and the latest single-cell RNA-sequencing technology, we plan to pursue the following specific aims. In aim 1, we will define the in vivo characteristics and function of periosteal and bone marrow SSPCs in clinically relevant OI mouse models. In aim 2, we will define key OI matrix factors that regulate SSPC function and improve both craniofacial and long bone healing. Upon completion of this work, we will achieve new biological insights into a better understanding of the molecular and cellular mechanisms that differentially regulate SSPCs under OI pathophysiological conditions.