CCND2 Overexpression Enhances the Regenerative Potency of Human Induced Pluripotent Stem Cell–Derived Cardiomyocytes: Remuscularization of Injured Ventricle

Rationale: The effectiveness of transplanted, human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) for treatment of ischemic myocardial injury is limited by the exceptionally low engraftment rate. Objective: To determine whether overexpression of the cell cycle activator CCND2 (cyclin D2) in hiPSC-CMs can increase the graft size and improve myocardial recovery in a mouse model of myocardial infarction by increasing the proliferation of grafted cells. Methods and Results: Human CCND2 was delivered to hiPSCs via lentiviral-mediated gene transfection. In cultured cells, markers for cell cycle activation and proliferation were ≈3- to 7-folds higher in CCND2-overexpressing hiPSC-CMs (hiPSC-CCND2 OE CMs) than in hiPSC-CMs with normal levels of CCND2 (hiPSC-CCND2 WT CMs; P OE CMs or hiPSC-CCND2 WT CMs but was about tripled in hiPSC-CCND2 OE CM–treated than in hiPSC-CCND2 WT CM–treated animals at week 4 ( P OE CM–treated animals ( P Conclusions: CCND2 overexpression activates cell cycle progression in hiPSC-CMs that results in a significant enhanced potency for myocardial repair as evidenced by remuscularization of injured myocardium. This left ventricular muscle regeneration and increased angiogenesis in border zone are accompanied by a significant improvement of left ventricular chamber function.