Tenomodulin高表达的骨髓间充质干细胞促进肌腱愈合的机制及应用研究

Mesenchymal stem cells (MSCs) are an important promising cell source for tissue engineering. Tendon injuries are very common and difficult to heal. Our previous study has found that MSCs could be induced to differentiate into tenocytes, and form cell sheet which could be used to heal tendon injury. Tenomodulin (Tnmd) has been demonstrated to be a specific marker of tendon and play important role in tendon development and maturation. In the pilot study, we have proved that bone marrow-derived MSCs (BM-MSCs) that highly express Tnmd could be differentiated into tenocytes more easily. So, in the present study we aim to use FITC-labeled Tnmd antibody to select MSCs highly expressing Tnmd, and observe whether the cell sheet formed by these MSCs are better or not for tissue-engineered tendon in nude mice as well as tondon injury healing in rat. In addition, in order to investigate novel genes that regulate tenogenic differentiation, we also use CHIP assay to analyze genes differentially expressed in MSCs that highly expressing Tnmd or not. This study will shed light on the tenogenic differentiation of MSCs, and provide new targets for application of MSCs in tendon healing.

间充质干细胞（MSCs）是组织工程中非常有前景的干细胞来源。肌腱损伤是常见的运动系统损伤，非常难以修复。我们的前期研究证明MSCs经体外诱导可分化为肌腱细胞，并且形成的细胞层片可用于肌腱损伤修复。Tenomodulin（Tnmd）是肌腱组织相对特异性的分子标志，在肌腱发育成熟中发挥着重要作用。我们的预实验结果证明Tnmd高表达的MSCs更易分化为肌腱细胞。本研究的目的在于建立以FITC标记的Tnmd抗体筛选Tnmd高表达与低表达的骨髓MSCs，经体外扩增培养、诱导分化后形成细胞层片，移植到裸鼠体内观察Tnmd高表达的MSCs能否更好地形成组织工程化肌腱及在大鼠肌腱损伤修复中能否发挥更好的作用。同时，我们将通过基因芯片技术分析Tnmd高表达与低表达的MSCs的区别，寻找调控成肌腱细胞分化的关键因子，从而为研究MSCs的肌腱细胞分化及其在肌腱修复中的应用提供新的靶点。

肌腱损伤是常见的运动系统损伤，非常难以修复，可能引起严重的发病率。间充质干细胞（MSCs）是组织工程中非常有前景的干细胞来源，已用于肌腱损伤的治疗，但MSCs在体内复杂生理环境中的低分化能力严重阻碍它的应用。我们的前期研究证明MSCs经体外诱导可分化为肌腱细胞，并且形成的细胞层片可用于肌腱损伤修复。Tenomodulin（Tnmd）是肌腱组织相对特异性的分子标志，在肌腱发育成熟中发挥着重要作用。我们发现Tnmd高表达的MSCs更易分化为肌腱细胞。本研究通过流式细胞仪筛选Tnmd高表达与低表达的骨髓MSCs，通过RNA测序技术分析Tnmd高表达与低表达的MSCs的基因表达的区别，找出调控成肌腱细胞分化的关键因子—GDF7，我们证明了GDF7在BMSCs高度表达Tnmd中被上调，抑制内源性GDF7显著抑制BMSCs的成肌腱细胞分化，从而证明GDF7在促进BMSCs的成肌腱分化方面发挥了重要作用。经体外扩增培养、诱导分化后形成细胞层片，移植到裸鼠体内证明Tnmd高表达的MSCs能更好地形成组织工程化肌腱，并且在大鼠肌腱损伤修复中能发挥更好的作用。综上所述，我们的研究表明Tnmd可以作为一种理想的细胞表面标记物来选择具有较高的成肌腱细胞分化能力的BMSCs细胞，而GDF7对于MSCs的发生是必不可少的。从而为研究MSCs的肌腱细胞分化及其在肌腱修复中的应用提供新的靶点。