Molecular Regulation of Cardiomyocyte Cell Cycle and Regeneration.

The regulation of the cardiomyocyte cell cycle is central to understanding heart regeneration. In adult mammals, cardiomyocytes withdraw from the cell cycle, limiting their ability to proliferate and repair heart tissue after injury. This process is controlled by intrinsic genetic programs and extrinsic signals, which together restrict the regenerative response in mature hearts. Understanding the mechanisms that regulate cardiomyocyte cell cycle activity is therefore critical for advancing cardiac regenerative medicine. In this review, we provide a comparative and integrated overview of cardiomyocyte cell cycle regulation in lower vertebrates and mammals, and discuss the major intrinsic factors that govern this process, including cyclin/CDK pathways, transcription factors and co-activators, oxygen and metabolic regulation, and epigenetic mechanisms. We also review the influence of hormones and growth factors, as well as the supportive roles of nonmyocyte populations in heart regeneration. By integrating findings across species, developmental stages, and regulatory levels, these findings highlight the complex regulatory network controlling cardiomyocyte proliferation and provide insight into potential therapeutic strategies for stimulating cardiac repair in the adult mammalian heart.