糖尿病肌腱病变的病理新机制：肌腱干细胞错误分化作用及其调控机制的研究

Tendon disorder is one of the common complications in diabetes mellitus (DM) patients. It is the main cause of chronic pain, limited joint mobility and tendon rapture among diabetic patients. Collagen fiber disturbance, advanced glycation end-products (AGEs) deposition and intratendinous calcific deposition are the main histopathological characteristics of tendon disorder in DM, which are associated with cell dysfunction in tendon tissue. Some studies had demonstrated that increased AGEs could induce ectopic bone formation in diabetic patients. However, the regulating mechanism of this alteration has not been completely elucidated. Recent studies showed that tendon stem/progenitor cells (TSPCs) may undergo erroneous differentiation into non-tenocytes, including osteocytes and chondrocytes, in some pathological conditions. Our preliminary experiment indicated that AGEs could induce erroneous differentiation of TSPCs in vitro. On the basis of our previous research, we use the human and rat TSPCs culture and streptozotocin (STZ) induced rat diabetic tendon disorder model to investigate the role of AGEs on erroneous differentiation of TSPCs in diabetic tendon disorder and the cellular and molecular mechanism of AGEs/RAGE signaling pathway in regulating erroneous differentiation of TSPCs by using pathological, cellular and molecular techniques. This study will provide new insight into the early prevention of tendon disorder in DM patients.

肌腱病变是糖尿病患者运动系统常见的并发症，是导致糖尿病患者慢性疼痛、运动受限、肌腱断裂的主要原因。其特征性病理表现为胶原纤维结构紊乱、晚期糖基化终末产物（AGEs）聚积和肌腱内钙化，这些与肌腱内细胞功能异常密切相关。研究表明，糖尿病患者多组织器官异位钙化与AGEs增高密切相关，但其作用机制尚不清楚。最近研究认为，病理状态下，肌腱组织内源性肌腱干细胞（TSPCs）可发生错误分化，成肌腱分化受限，而成骨和成软骨细胞分化增强。我们预实验结果提示，AGEs可诱导TSPCs向非肌腱细胞发生错误分化。本研究拟在前期TSPCs错误分化研究的基础上，通过体外人、大鼠TSPCs培养以及大鼠糖尿病肌腱病变模型，利用组织、细胞和分子生物学等手段，探讨TSPCs错误分化与糖尿病肌腱病变的关系，以阐明AGEs/RAGE信号通路对TSPCs错误分化的作用及调控机制，为积极防治糖尿病肌腱病变提供新颖的思路和理论依据。

糖尿病肌腱病病理机制尚未阐明，临床缺乏有效的防治方案。前期研究结果提示：肌腱干细胞（TSPCs）和晚期糖基化终末产物（AGEs）都可能参与其病理过程，导致肌腱中出现非肌腱细胞表型﹑组织化生和肌腱愈合失败。本课题通过体外比较大鼠健康和糖尿病髌腱组织内TSPCs的数量﹑增殖能力以及成骨和成软骨和成肌腱分化功能的差异，验证并阐述了TSPCs错误分化参与糖尿病肌腱病的发病过程，是导致糖尿病肌腱病重要的细胞病理学机制。通过评估AGEs对大鼠健康肌腱来源的TSPCs成骨﹑成软骨和成肌腱分化的作用，在细胞与分子水平验证AGEs可促进TSPCs成骨和成软骨分化，增加钙﹑蛋白多糖沉积，抑制成肌腱分化，减少肌腱样组织形成，阐述TSPCs错误分化可受AGEs的调控。通过体外比较基础条件下和AGEs作用下，以及在特异性RAGE抑制剂N-methylpyridinium作用下，大鼠健康髌腱组织来源的TSPCs中AGEs/RAGE通路的活化状态及其差异，以及这些细胞中成骨、成软骨和成肌腱分化特异性基因表达水平的变化及其差异，深入探索和验证糖尿病肌腱病的发病过程中，AGEs与RAGE结合增多，上调成骨和成软骨基因，同时下调成肌腱分化基因，实现对肌腱干细胞错误分化的调控作用。本课题的顺利实施，初步阐明TSPCs错误分化在糖尿病肌腱病中的作用，以及AGEs/RAGE信号通路对TSPCs错误分化的调控作用及其分子机制，为糖尿病肌腱病的病理机制研究提供新观点，也为临床建立有效的防治策略提供新线索。