Myocardial infarction (MI) is one of the major cardiovascular diseases caused by diminished supply of nutrients and oxygen to the heart due to obstruction of the coronary artery. Different treatment options are available for cardiac diseases, however, they do not completely repair the damage. Therefore, reprogramming terminally differentiated fibroblasts using transcription factors is a promising strategy to differentiate them into cardiac like cells in vitro and to increase functional cardiomyocytes and reduce fibrotic scar in vivo. In this study, skin fibroblasts were selected for reprogramming because they serve as a convenient source for the autologous cell therapy. Fibroblasts were isolated from skin of rat pups, propagated, and directly reprogrammed towards cardiac lineage. For reprogramming, two different approaches were adopted, i.e., cells were transfected with: (1) combination of cardiac transcription factors; GATA4, MEF2c, Nkx2.5 (GMN), and (2) combination of cardiac transcription factors; GATA4, MEF2c, Nkx2.5, and iPSC factors; Oct4, Klf4, Sox2 and cMyc (GMNO). After 72 h of transfection, cells were analyzed for the expression of cardiac markers at the mRNA and protein levels. For in vivo study, rat MI models were developed by ligating the left anterior descending coronary artery and the reprogrammed cells were transplanted in the infarcted heart. qPCR results showed that the reprogrammed cells exhibited significant upregulation of cardiac genes. Immunocytochemistry analysis further confirmed cardiomyogenic differentiation of the reprogrammed cells. For the assessment of cardiac function, animals were analyzed via echocardiography after 2 and 4 weeks of cell transplantation. Echocardiographic results showed that the hearts transplanted with the reprogrammed cells improved ejection fraction, fractional shortening, left ventricular internal systolic and diastolic dimensions, and end systolic and diastolic volumes. After 4 weeks of cell transplantation, heart tissues were harvested and processed for histology. The histological analysis showed that the reprogrammed cells improved wall thickness of left ventricle and reduced fibrosis significantly as compared to the control. It is concluded from the study that novel combination of cardiac transcription factors directly reprogrammed skin fibroblasts and differentiated them into cardiomyocytes. These differentiated cells showed cardiomyogenic characters in vitro, and reduced fibrosis and improved cardiac function in vivo. Furthermore, direct reprogramming of fibroblasts transfected with cardiac transcription factors showed better regeneration of the injured myocardium and improved cardiac function as compared to the indirect approach in which combination of cardiac and iPSC factors were used. The study after further optimization could be used as a better strategy for cell-based therapeutic approaches for cardiovascular diseases.

心肌梗死（MI）是由于冠状动脉阻塞导致心脏营养和氧气供应减少而引起的主要心血管疾病之一。心脏病有不同的治疗方案，但是它们并不能完全修复损伤。因此，使用转录因子对终末分化的成纤维细胞进行重编程是一种有前景的策略，可将其在体外分化为心脏样细胞，并在体内增加功能性心肌细胞并减少纤维化疤痕。在这项研究中，选择皮肤成纤维细胞进行重编程，因为它们是自体细胞疗法的便捷来源。从大鼠幼崽的皮肤中分离出成纤维细胞，进行增殖，并直接重新编程为心脏谱系。对于重编程，采用了两种不同的方法，即用以下物质转染细胞：（1）心脏转录因子的组合；GATA4 、MEF2c、Nkx2.5 (GMN) 和 (2) 心脏转录因子的组合；GATA4、MEF2c、Nkx2.5 和 iPSC 因子；Oct4、Klf4、Sox2 和 cMyc (GMNO)。转染 72 小时后，分析细胞mRNA 和蛋白质水平上心脏标志物的表达。对于体内研究，通过结扎左冠状动脉前降支建立大鼠心肌梗死模型，并将重编程的细胞移植到梗塞心脏中。qPCR 结果显示，重编程细胞表现出心脏基因的显着上调。免疫细胞化学分析进一步证实了重编程细胞的心肌分化。为了评估心脏功能，在细胞移植2 周和 4 周后通过超声心动图对动物进行分析。超声心动图结果显示，移植了重编程细胞的心脏改善了射血分数、缩短分数、左心室收缩期和舒张期内径以及收缩末期和舒张期容积。细胞移植4周后，收获心脏组织并进行组织学处理。组织学分析表明，与对照相比，重编程细胞显着改善了左心室壁厚度并减少了纤维化。研究得出的结论是，心脏转录因子的新型组合直接重新编程皮肤成纤维细胞并将其分化为心肌细胞。这些分化的细胞在体外表现出心肌形成特征，并在体内减少纤维化并改善心脏功能。。此外，与使用心脏和 iPSC 因子组合的间接方法相比，用心脏转录因子转染的成纤维细胞的直接重编程显示出更好的受损心肌再生和改善的心脏功能。进一步优化后的研究可作为心血管疾病细胞治疗方法的更好策略。