HSA+ immature cardiomyocytes persist in the adult heart and expand after ischemic injury
The assessment of the regenerative capacity of the heart has been compromised by the lack of surface signatures to characterize cardiomyocytes. Here, combined multiparametric surface marker analysis with single cell transcriptional profiling and in vivo transplantation, identify the main fetal cardiac populations and their progenitors. We found that cardiomyocytes at different stages of differentiation co-exist during development. We identified a population of immature HSA/CD24+ cardiomyocytes that persists throughout life and that, unlike other cardiomyocyte subsets, actively proliferates up to one week of age and engraft cardiac tissue upon transplantation. In adult heart HSA/CD24+ cardiomyocytes appear as mononucleated cells that cycle and increase in frequency after infarction. Our work identified cell surface signatures that allow the prospective isolation of cardiomyocytes at any developmental stage and the detection of adult cardiomyocytes poised for activation in response to ischemic stimuli. This work opens new perspectives in the understanding and treatment of heart pathologies.