心脏肌成纤维细胞对心肌细胞分化的影响及分子机制：电偶联或机械偶联？

Cardiac cell therapy has been explored for its potential to regenerate the damaged heart via cardiomyogenic differentiation of transplanted cells. Unfortunately, so far, without much success. This might be due to the lack of knowledge about how the damaged tissue affects formation of heart muscle cells from transplanted cells. After injury, cardiac fibroblasts (FB) contribute to wound healing by differentiation into myofibroblasts (MFB). Compare to FB, MFB were found to inhibit cardiomyogenic differentiation of a co-cultured cell model in our pilot experiment. Furthermore, MFB were reported to depression of neighboring cardiomyocytes via electrical and mechanical coupling. These evidence suggest that MFB may affect cardiac differentiation through electrical and mechanical interaction with guest cells. In this study, the effects of MFB on cardiomyogenic differentiation will be investigated from both electrical and mechanical coupling in cell culture models. Pharmacological and genetic interventions will be used for identifying causal factors, while complementary molecular and electrophysiological techniques will be used to obtain structural and functional data for characterization of differentiation. This project is expected to reveal unique new mechanistic insights into the role of the MFB in modulating cardiomyogenic differentiation. Such understanding may provide new clues for increasing the therapeutic potential of transplantation-based cardiac regenerative medicine.

细胞移植对心脏疾病已展示出良好治疗前景，但心肌损伤后局部组织微环境的纤维细胞（FB）及其分化的肌成纤维细胞（MFB）形成的疤痕组织，成为影响细胞移植疗效的主要因素。前期研究显示MFB可通过直接电偶联和机械偶联两种方式抑制相邻心肌细胞的正常功能，MFB和FB与心肌前体细胞共培养会显著其抑制心肌分化能力，但目前机制不明。据此，本课题将应用高分化潜能的永生化心肌前体细胞模型，在体外评定MFB抑制其心肌分化和再生修复性能的作用、关键影响因素及主要作用机理，并着重从电耦连和机械力耦连两方面，观察分化细胞的肌小结结构、单细胞水平电生理特性、细胞间动作电位传导及钙瞬变等，探索MFB影响前体细胞向心肌分化的潜在作用靶点，阐释其影响心肌分化的作用机制，并尝试通过药物作用或/和基因干扰技术阻断MFB的作用。本研究可望为开发和优化心肌损伤的干细胞移植治疗提供更深入的依据和基础。

心肌梗塞仍然是全世界死亡的主要原因。许多研究表明，植入干细胞可以减少心脏瘢痕的大小，并改善受伤心肌的功能恢复。一旦移植进入受损的心肌组织，干细胞被心肌损伤后形成的纤维化环境和炎症环境包围。肌成纤维细胞是心肌纤维化的关键细胞类型，而巨噬细胞是参与心肌梗死后炎症过程的关键细胞类型。更好地了解心肌病理微环境，包括纤维化和炎症环境，如何影响干细胞存活和心脏分化能力，将最大限度地提高治疗效果。然而，以前的研究通常集中在肌成纤维细胞和巨噬细胞对现有心肌细胞的影响，大多没有考虑肌成纤维细胞和巨噬细胞在干细胞存活和成心肌分化中的作用。因此，在本研究中，我们区分并表征了肌成纤维细胞和三种巨噬细胞亚型，通过共培养的方式，评估了它们对干细胞成心肌分化能力的影响。结果证明，肌成纤维细胞及M1巨噬细胞在肌体结构、收缩和电生理基因表达以及线粒体呼吸方面抑制了共培养干细胞的心肌分化能力。与M1巨噬细胞相比，M2巨噬细胞显示出促进心肌分化的效果。研究成果将为改善干细胞再生治疗心肌损伤提供新的知识。