Transient Introduction of miR-294 in the Heart Promotes Cardiomyocyte Cell Cycle Reentry After Injury

Rationale: Embryonic heart is characterized by of rapidly dividing cardiomyocytes required to build a working myocardium. Cardiomyocytes retain some proliferative capacity in the neonates but lose it in adulthood. Consequently, a number of signaling hubs including microRNAs are altered during cardiac development that adversely impacts regenerative potential of cardiac tissue. Embryonic stem cell cycle (ESCC) miRs are a class of microRNAs exclusively expressed during developmental stages however their effect on cardiomyocyte proliferation and heart function in adult myocardium has not been previously studied. Objective: To determine whether transient reintroduction of ESCC miR-294 promotes cardiomyocyte cell cycle reentry enhancing cardiac repair after myocardial injury. Methods and Results: miR-294 is expressed in the heart during development, prenatal stages, lost in the neonate and adult heart confirmed by qRT-PCR and in situ hybridization. Neonatal ventricular myocytes (NRVMs) treated with miR-294 show...