Department of Biomedical Engineering University of Alabama at Birmingham Birmingham AL USA.
Department of Medicine, Cardiovascular Disease University of Alabama at Birmingham Birmingham AL USA.
J Am Heart Assoc. 2024 Nov 5;13(21):e037120. doi: 10.1161/JAHA.124.037120. Epub 2024 Oct 29.
The proliferative capacity of cardiomyocytes in adult mammalian hearts is far too low to replace the cells that are lost to myocardial infarction. Both cardiomyocyte proliferation and myocardial regeneration can be improved via the overexpression of a constitutively active variant of YAP5SA (Yes-associated protein, 5SA [active] mutant), but persistent overexpression of proliferation-inducing genes could lead to hypertrophy and arrhythmia, whereas off-target expression in fibroblasts and macrophages could increase fibrosis and inflammation.
Transient overexpression of YAP5SA or GFP (green fluorescent protein; control) was targeted to cardiomyocytes via our cardiomyocyte-specific modified mRNA translation system (CM-SMRTs or CM-SMRTs, respectively). YAP5SA-cardiomyocyte specificity was confirmed via in vitro experiments in cardiomyocytes and cardiac fibroblasts that had been differentiated from human induced- pluripotent stem cells and in human umbilical-vein endothelial cells, and the regenerative potency of CM-SMRTs was evaluated in a mouse myocardial infarction model. In cultured human induced-pluripotent stem cells-cardiomyocytes, YAP was abundantly expressed for 3 days after CM-SMRTs administration and was accompanied by increases in the expression of markers for proliferation, before declining to near-background levels after day 7, whereas GFP fluorescence remained high from days 1 to 3 after CM-SMRTs treatment and then slowly declined. GFP fluorescence was also observed in human induced-pluripotent stem cells-cardiac fibroblasts and human umbilical-vein endothelial cells on day 1 after CM-SMRTs administration but declined substantially by day 3. In the mouse myocardial infarction model, echocardiographic assessments of left-ventricular ejection fraction and fractional shortening were significantly greater, whereas infarct sizes were significantly smaller in CM-SMRTs-treated mice than in vehicle-treated control animals, and CM-SMRTs appeared to promote cardiomyocyte proliferation.
The CM-SMRTs can be used to transiently and specifically overexpress YAP5SA in cardiomyocytes, and this treatment strategy significantly promoted cardiomyocyte proliferation and myocardial regeneration in a mouse myocardial infarction model.
成年哺乳动物心脏中的心肌细胞的增殖能力太低，无法替代因心肌梗死而丧失的细胞。通过过表达一种组成型激活的 YAP5SA（Yes 相关蛋白，5SA[激活]突变体），可以提高心肌细胞的增殖能力和心肌再生能力，但持续过表达增殖诱导基因可能导致肥大和心律失常，而在成纤维细胞和巨噬细胞中的非靶向表达可能会增加纤维化和炎症。
通过我们的心肌细胞特异性修饰 mRNA 翻译系统（CM-SMRTs 或 CM-SMRTs，分别），将 YAP5SA 或 GFP（绿色荧光蛋白；对照）的瞬时过表达靶向到心肌细胞。通过在体外实验中从人诱导多能干细胞分化的心肌细胞和心肌成纤维细胞以及人脐静脉内皮细胞中证实了 YAP5SA 的心肌细胞特异性，并在小鼠心肌梗死模型中评估了 CM-SMRTs 的再生能力。在培养的人诱导多能干细胞-心肌细胞中，在给予 CM-SMRTs 后第 3 天，YAP 大量表达，并伴随着增殖标志物表达的增加，然后在第 7 天降至接近背景水平，而 GFP 荧光在给予 CM-SMRTs 后第 1 天至第 3 天仍保持高水平，然后缓慢下降。在给予 CM-SMRTs 后第 1 天也观察到 GFP 荧光在人诱导多能干细胞-心肌成纤维细胞和人脐静脉内皮细胞中，但在第 3 天显著下降。在小鼠心肌梗死模型中，左心室射血分数和缩短分数的超声心动图评估在 CM-SMRTs 治疗组中显著更高，而梗塞面积在 CM-SMRTs 治疗组中显著小于对照组，CM-SMRTs 似乎促进了心肌细胞增殖。
CM-SMRTs 可用于在心肌细胞中瞬时且特异性地过表达 YAP5SA，并且这种治疗策略在小鼠心肌梗死模型中显著促进了心肌细胞增殖和心肌再生。
