Developmental origin of postnatal cardiomyogenic progenitor cells

To trace the cell origin of the cells involved in postnatal cardiomyogenesis. Nkx2.5 enhancer-eGFP (Nkx2.5 enh-eGFP) mice were used to test the cardiomyogenic potential of Nkx2.5 enhancer-expressing cells. By analyzing Cre excision of activated Nkx2.5-eGFP+ cells from different lineage-Cre/Nkx2.5 enh-eGFP/ROSA26 reporter mice, we traced the developmental origin of Nkx2.5 enhancer-expressing cells. Nkx2.5 enhancer-expressing cells could differentiate into striated cardiomyocytes both and . Nkx2.5-eGFP+ cells increased remarkably after experimental myocardial infarction (MI). The post-MI Nkx2.5-eGFP+ cells originated from the embryonic epicardial cells, not from the pre-existing cardiomyocytes, endothelial cells, cardiac neural crest cells or perinatal/postnatal epicardial cells. Postnatal Nkx2.5 enhancer-expressing cells are cardiomyogenic progenitor cells and originate from embryonic epicardium-derived cells. Recent studies report that postnatal mammalian hearts undergo cardiomyocyte refreshment; however, evidence is lacking for the cell origin of the cells involved in postnatal cardiomyogenesis. In this study, we confirmed that Nkx2.5 cardiac progenitor cells existed in the postnatal mouse heart and could differentiate into striated cardiomyocytes both and . The developmental origin of these postnatal Nkx2.5 cardiac progenitor cells are from the embryonic epicardial cells.