胸腺素β4对肌腱干细胞生物学特性的调控作用及其促进肌腱优质愈合的分子机制

Tendon heals slowly by scar formation after injury. The biological properties of healing tissue are inferior to the normal tendon tissue, which lead to impairment of function. Thymosin β4 (Tβ4) is mainly recognized as a regulator of actin polymerization by sequestering G-actin. Recent studies have demonstrated that Tβ4 is a multifunctional peptide. It promotes a variety of physiological functions such as proliferation, chemotaxis, tissue repair, and tissue remodeling. We found that the administration of Tβ4 accelerated tendon healing and improved the organization of collagen fibers in the repair site of tendon tissue. In the present research, we hypotheses that Tβ4 could optimize the repair of injured tendon by regulating tendon stem cells. Moreover, Tβ4 may play important role in the restoration of structure and function after tendon injury by modulating myofibroblast differentiation and the balance of MMP/TIMP system during tendon healing process, which result in optimized regeneration. We hypotheses that Tβ4 optimize the regeneration of injured tendon by regulating above mentioned mechanisms and interfering with Rho/ROCK signal pathway, which served as the breakthrough point in this study. We will further explore the underlying molecular mechanism of Tβ4 improving the histological, biochemical and biomechanical properties of the healing tendon in this study. Tendon stem cells and fibroblasts cultured in vitro and the animal model of patellar tendon injury were used in the experiment. The result of this research may provide a new treatment strategy and theoretical basis for improving the quality of the healing tendon tissue.

肌腱损伤后愈合速度慢，并且常呈瘢痕性愈合，其生物学特性显著差于正常肌腱，严重影响功能。胸腺素β4（thymosin β4,Tβ4）是具有促细胞增殖分化、迁移及促进基质重塑等多种生物学功能的G-肌动蛋白结合肽。我们前期研究结果表明：Tβ4可以加快肌腱愈合速度并且使愈合后肌腱胶原纤维排列更为规则。本课题设想Tβ4可以通过调控肌腱干细胞生物学特性促进肌腱修复，另外，Tβ4对愈合过程中肌成纤维细胞转分化以及MMP/TIMP系统平衡表达可能亦具有调节作用，进而达到优质愈合。本课题以Tβ4是否通过调控上述机制来优化肌腱愈合以及其是否通过干扰Rho／ROCK信号转导通路发挥作用为切入点，拟利用大鼠肌腱干细胞、成纤维细胞体外培养及髌腱急性损伤动物模型，探索Tβ4在组织学、生物化学及生物力学等方面优化肌腱愈合的内在分子机制，本研究的成功实施将为提高肌腱愈合质量提供新的治疗策略和理论依据。

肌腱损伤后愈合速度慢，并且常呈瘢痕性愈合，愈合后其生物学特性显著差于正常肌腱，严重影响功能。胸腺素β4（thymosin β4,Tβ4）是具有促细胞增殖分化、迁移及促进基质重塑等多种生物学功能的G-肌动蛋白结合肽。近年来被发现是促进愈合的有效物质，它可以提高皮肤、韧带和肌腱愈合的速度与质量。本课题探讨了Tβ4对肌腱干细胞生物学特性的调控及促进肌腱修复的作用。利用大鼠肌腱干细胞体外培养，观察Tβ4对肌腱干细胞增殖、迁移、腱系分化及干性维持的影响；动物实验采用SD大鼠髌腱损伤模型，通过HE染色、免疫组织化学、电镜及生物力学检测观察Tβ4对髌腱愈合的影响。经本课题的研究发现：Tβ4显著缩短了肌腱干细胞的倍增时间；Tβ4能明显诱导肌腱干细胞分化，同时其可以有效促进腱向分化相关基因的表达 (上述实验结果均具有统计学意义，P<0.05)。在体动物模型揭示了Tβ4可以使愈合后肌腱胶原纤维排列更为规则，减轻愈合局部瘢痕的形成，阻抑了愈合过程中ROCK通路的激活。这为优化肌腱干细胞的实验研究提供了有利的理论依据，为肌腱损伤后优质愈合提供了新的思路方法。