Disrupting methyl-CpG-binding protein 2 expression induces the transformation of iPSC-CMs into pacemaker-like cells by insulin gene enhancer binding protein 1.

Development of biological pacemaker cells is highly essential to avoid the long-term negative effects of pacemaker use such as pacemaker-induced heart failure. Differentiation of induced pluripotent stem cells (iPSCs) into cardiomyocytes (CMs) can be induced via the regulation of the Wnt signaling pathway. Real-time quantitative PCR (qPCR), western blotting, immunofluorescence staining, and patch-clamp technique were used to analyze the ability of ISL1 to induce the transformation of iPSC-CMs into pacemaker-like cells. RT-qPCR and patch-clamp analyses showed that overexpression of ISL1 induced the successful differentiation of iPSC-CMs into pacemaker cells. ISL1-overexpressing pacemaker-like cells possessed typical characteristics of pacemaker morphology, including action potential and If inward current. Calcium spark, patch-clamp technique, and real-time qPCR were used to verify whether disrupting the expression of MeCP2 enhanced this ability of ISL1 to induce the differentiation of iPSC-CMs into pacemaker cells. Chromatin immunoprecipitation results showed that MeCP2 bound to the promoter region of HCN4. Following disruption of MeCP2 expression, the gene expression of sinoatrial node-specific transcription factors, If inward current, and cardiac rhythm changes in iPSC-CMs resembled those of sinoatrial node pacemaker cells. Therefore, ISL1 induced the differentiation of iPSC-CMs into pacemaker-like cells, and knockdown of MeCP2 increased this effect. The obtained pacemaker-like cells were transplanted into the apical tissue of mice hearts to verify their long-term survival. We found that the experimentally obtained pacemaker-like cells could survive for a long time in myocardial tissues in vivo. Our findings may aid development of novel strategies for heart disease.