Murine neonatal cardiac B cells promote cardiomyocyte proliferation and heart regeneration

Since the proliferative capacity of cardiomyocytes is extremely limited in the adult mammalian hearts, the irreversible loss of cardiomyocytes following cardiac injury markedly reduces cardiac function, leading to cardiac remodeling and heart failure. However, the early neonatal mice have a strong ability in cardiomyocyte proliferation and cardiac regeneration after heart damage such as apical resection. Besides of cardiomyocytes, non-myocytes in heart tissue also play important roles in the regeneration process. Previous studies showed that cardiac macrophages, regulatory T cells and CD4+ T cells are all involved in regulating the myocardial regeneration process. However, the roles of other cardiac immune cells in cardiac regeneration remains to be elucidated. B cells is a prominent immune cell in injured heart; here we discovered the indispensable function of cardiac B cells in improving cardiomyocyte proliferation and heart regeneration in neonatal mice. WT P1 and P7 mice were performed on apical resection (AR). At day 7 after AR, heart tissue were harvested and CD45+ cells were isolated from heart tisssue for single-cell RNA sequencing.