Skeletal muscle (SKM) is the largest organ in mammalian body and it can repair damages by using the residential myogenic stem cells (MuSC), but this repairing capacity reduces with age and in some genetic muscular dystrophy. Under these circumstances, artificial amplification of autologous MuSC in vitro might be necessary to repair the damaged SKM. The amplification of MuSC is highly dependent on myogenic signals, such as sonic hedgehog (Shh), Wnt3a, and fibroblast growth factors, so formulating an optimum myogenic kit composed of specific myogenic signals might increase the proliferation and differentiation of MuSC efficiently. In this study, various myogenic signals have been tested on C2C12 myoblasts and primary MuSC, and a myogenic kit consists of insulin, lithium chloride, T3, and retinoic acid has been formulated, and we found it significantly increased the fusion index and MHC expression level of both C2C12 and MuSC myotubes. A novel bioreactor providing cyclic stretching (CS) and electrical stimulation (ES) has been fabricated to enhance the myogenic differentiation of both C2C12 and MuSC. We further found that coating the bioreactor substratum with collagen gave the best effect on proliferation and differentiation of MuSC. Furthermore, combining the collagen coating and physical stimuli (CS + ES) in the bioreactor can generate more proliferative primary MuSC cells. Our results have demonstrated that the combination of myogenic kit and bioreactor can provide environment for efficient MuSC proliferation and differentiation. These MuSC and mature myotubes amplified in the bioreactor might be useful for clinical grafting into damaged SKM in the future.

中文翻译：

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骨骼肌干细胞的增殖和分化在生物反应器中得到增强


骨骼肌 （SKM） 是哺乳动物体内最大的器官，它可以通过使用住宅肌源干细胞 （MuSC） 来修复损伤，但这种修复能力会随着年龄的增长和一些遗传性肌营养不良症而降低。在这些情况下，可能需要在体外人工扩增自体 MuSC 来修复受损的 SKM。MuSC 的扩增高度依赖于成肌信号，例如声刺猬 （Shh）、Wnt3a 和成纤维细胞生长因子，因此配制由特定成肌信号组成的最佳成肌试剂盒可能会有效地增加 MuSC 的增殖和分化。在这项研究中，在 C2C12 成肌细胞和原代 MuSC 上测试了各种成肌信号，并配制了由胰岛素、氯化锂、T3 和视黄酸组成的成肌试剂盒，我们发现它显着增加了 C2C12 和 MuSC 肌管的融合指数和 MHC 表达水平。已经制造了一种提供循环拉伸 （CS） 和电刺激 （ES） 的新型生物反应器，以增强 C2C12 和 MuSC 的肌源分化。我们进一步发现，用胶原蛋白包被生物反应器基质对 MuSC 的增殖和分化效果最好。此外，在生物反应器中结合胶原蛋白涂层和物理刺激 （CS + ES） 可以产生更多增殖的原代 MuSC 细胞。我们的结果表明，生肌试剂盒和生物反应器的组合可以为 MuSC 的高效增殖和分化提供环境。这些在生物反应器中扩增的 MuSC 和成熟肌管将来可能有助于临床嫁接到受损的 SKM 中。