Pharmacologically inducing regenerative cardiac cells by small molecule drugs

Abstract

In contrast to lower organisms, adult mammals cannot regenerate damaged hearts through de-differentiation of cardiomyocytes (CMs) into cells with regenerative capacity. Development of an enabling condition to induce such naturally unavailable cells with potential to proliferate and differentiate into CMs, i.e., regenerative cardiac cells (RCCs), in mammals will provide new insights and tools for heart regeneration. Here, a two-compound combination (2C), CHIR99021 and A-485, was identified to robustly induce RCCs from human embryonic stem cell (hESC) derived TNNT2 + CMs in vitro , which was confirmed by lineage tracing experiments. Functional analyses revealed that RCCs expressed a spectrum of genes essential for cardiogenesis and exhibited potential to become functional CMs, endothelial cells (ECs) and smooth muscle cells (SMCs). Consistent with the results in human cells, 2C-induced generation of RCCs were also observed in neonatal rats CMs in vitro and in vivo . Remarkably, administration of 2C can induce RCCs in adult mouse hearts and significantly improve survival and heart function in the mice undergoing myocardial infarction. Mechanistically, CHIR99021 is indispensable for transcriptional and epigenetic activation of genes essential for RCC, whereas A-485 mainly function to epigenetically down-regulate H3K27Ac and particularly H3K9Ac in CMs. Their combination specifically enhances both H3K27Ac and H3K9Ac on RCC genes, facilitating the establishment of RCC state dedifferentiated from CMs. Therefore, our findings demonstrated the feasibility and revealed the mechanisms of pharmacological induction of RCCs from endogenous CMs, which could offer a promising regenerative strategy to repair injured hearts.