肌腱干细胞分化调控对肌腱微损伤修复的作用及机制

Tendinopathy is the most common sports injury that often occurs from overuse. Micro-injury to the tendon leads to ectopic ossification and adipose in the tendon. Tendon Stem Cells (TSCs), which are progenitor cells of tenocyte, play the key role in repairing tendon micro-injury. The regulation of TSCs differentiation is the scientifically key issue for tendon micro-injury repair. In our initial research, it was found that overload stretching results in abnormal TSCs differentiation, and affects the TSCs skeleton and shape. Other researchers found that the changed cytoskeleton and cell shape activated the Rho family signal channel, and further caused cell differentiation in embryonic stem cells. This project, with various techniques such as knockdown, from the "mechanics-and-biology" coupling view, aims to explore the mechanism of TSCs skeleton and shape change caused by mechanical strecthing, analyze the signal channel and regulation factors of Rho family activated by TSCs skeleton and shape change, and investigate osteogenesis through RhoA/ROCK2/BMP-2 pathway, adipogenesis through RhoA/ROCK2/Wnt/β-catenin pathway and tenogenesis through Rac1/N-cadherin pathway. Moreover, on this basis, it intends to analyze the key factors for TSCs normal and abnormal differentiation, discuss the role and mechanism of TSCs differentiation regulation in repairing tendon micro-injury, and provide new ideas for the tendinopathy prevention and treatment.

肌腱病是最常见的运动损伤性疾病，由过度使用引起肌腱微损伤，导致腱组织异位骨化和脂肪化。肌腱干细胞(TSCs)是肌腱细胞唯一前体细胞，对肌腱微损伤修复起决定性作用；TSCs分化调控是肌腱微损伤修复的关键科学问题。我们前期研究发现，过度牵伸导致TSCs异常分化；影响TSCs骨架与形变。有研究发现，细胞骨架与形变激活Rho家族信号通道导致胚胎干细胞分化。本课题拟采用knockdown等多种技术手段，从"力学-生物学"藕合角度，探讨机械牵伸引起TSCs骨架和形变的机制，分析TSCs骨架和形变激活Rho家族的信号通路和调控因素，研究RhoA/ROCK2/BMP-2通路成骨、RhoA/ROCK2/Wnt/β-catenin通路成脂和Rac1/N-cadherin通路成肌腱分化的机制；分析影响TSCs异常和正常分化的关键因素，探讨TSCs分化调控在肌腱微损伤修复过程的作用及机制，为肌腱病防治提供新思路。

本项目以“适度机械牵伸―干细胞肌腱（tendon stem cells, TSCs）细胞正常分化—肌腱正常修复”和“过度机械牵伸― TSCs细胞异常分化—肌腱微损伤—修复失败”为生物学背景，从力学-生物学耦合规律角度出发，解决机械牵伸如何诱导和控制TSCs分化以及TSCs不同分化方向导致肌腱微损伤修复后不同转归的关键科学问题。. 按照项目原计划的规划，课题组从机械牵伸对TSCs细胞骨架重塑和形态变化的影响；TSCs骨架重塑和形态变化对有关胞内信号通路的影响以及不同信号通路在诱导TSCs成骨、成脂或成肌腱分化中的作用及其机制三个方面，进行了以下的研究并取得了一定的成果。. 通过本项目研究，确定了诱导TSCs向不同方向分化的牵伸条件，在此基础上，确定了导致TSCs成肌腱、成骨与成软骨以及成脂分化所涉及到的信号通路。阐明了适度机械牵伸促进TSCs细胞正常分化，有利于肌腱正常修复；过度机械牵伸诱导TSCs细胞异常分化，导致肌腱微损伤修复失败引起肌腱病的相关机制。探索了TSCs异常分化和肌腱微损伤修复的潜在靶点，为肌腱微损伤的发病机制研究提供了新的实验证据。建立了肌腱病的动物模型以及优化了治疗肌腱病的跑台训练条件，为肌腱病康复训练提供了实验证据。. 目前发表论文共计31篇，其中国内15篇，国外SCI论文16篇(最高IF=4.652，篇均IF=3.276)，另有5篇撰写中。参加学术会议20次，大会/分会发言60人次。本研究团队-运动损伤修复与重建研究创新团队入选国家创新人才推进计划-重点领域创新团队及获得国家重点研发计划。获得批准授权的发明专利1项，实用新型专利1项，培养博士后1名、博士15名、硕士10名。这些成果为阐明肌腱微损伤的发病机制、治疗以及预防和人才队伍的培养都具有极为重要意义。