Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
Department of Biomedical Engineering, Yale University, New Haven, CT, USA; Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, CT, USA.
J Mol Cell Cardiol. 2021 Sep;158:11-25. doi: 10.1016/j.yjmcc.2021.05.005. Epub 2021 May 14.
We have created a novel in-vitro platform to study reverse remodeling of engineered heart tissue (EHT) after mechanical unloading. EHTs were created by seeding decellularized porcine myocardial sections with a mixture of primary neonatal rat ventricular myocytes and cardiac fibroblasts. Each end of the ribbon-like constructs was fixed to a plastic clip, allowing the tissues to be statically stretched or slackened. Inelastic deformation was introduced by stretching tissues by 20% of their original length. EHTs were subsequently unloaded by returning tissues to their original, shorter length. Mechanical characterization of EHTs immediately after unloading and at subsequent time points confirmed the presence of a reverse-remodeling process, through which stress-free tissue length was increased after chronic stretch but gradually decreased back to its original value within 9 days. When a cardiac myosin inhibitor was applied to tissues after unloading, EHTs failed to completely recover their passive and active mechanical properties, suggesting a role for actomyosin contraction in reverse remodeling. Selectively inhibiting cardiomyocyte contraction or fibroblast activity after mechanical unloading showed that contractile activity of both cell types was required to achieve full remodeling. Similar tests with EHTs formed from human induced pluripotent stem cell-derived cardiomyocytes also showed reverse remodeling that was enhanced when treated with omecamtiv mecarbil, a myosin activator. These experiments suggest essential roles for active sarcomeric contraction and fibroblast activity in reverse remodeling of myocardium after mechanical unloading. Our findings provide a mechanistic rationale for designing potential therapies to encourage reverse remodeling in patient hearts.
我们创建了一种新颖的体外平台,用于研究机械卸载后工程心脏组织(EHT)的反向重构。EHT 是通过将原代新生大鼠心室肌细胞和心肌成纤维细胞的混合物接种到脱细胞猪心肌切片上来构建的。带状结构的每一端都固定在塑料夹上,使组织可以静态拉伸或松弛。通过将组织拉伸到原始长度的 20%来引入非弹性变形。然后通过将组织恢复到原始较短的长度来卸载 EHT。EHT 在卸载后和随后的时间点进行机械特性分析,证实了存在反向重构过程,通过该过程,在慢性拉伸后无应力组织长度增加,但在 9 天内逐渐恢复到原始值。当在卸载后将心脏肌球蛋白抑制剂应用于组织时,EHT 未能完全恢复其被动和主动机械特性,这表明肌球蛋白收缩在反向重构中起作用。在机械卸载后选择性抑制心肌细胞收缩或成纤维细胞活性表明,两种细胞类型的收缩活性对于实现完全重构是必需的。用源自人诱导多能干细胞的心肌细胞构建的 EHT 进行类似的测试也显示出反向重构,当用肌球蛋白激活剂 omecamtiv mecarbil 处理时,这种重构得到增强。这些实验表明,在机械卸载后心肌的反向重构中,活性肌节收缩和成纤维细胞活性起着重要作用。我们的发现为设计潜在的治疗方法以鼓励患者心脏的反向重构提供了机制基础。