Long-Term Engraftment of Human Cardiomyocytes Combined with Biodegradable Microparticles Induces Heart Repair

Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CMs) are a promising cell source for cardiac repair after myocardial infarction (MI) because they offer several advantages such as potential to remuscularize infarcted tissue, integration in the host myocardium, and paracrine therapeutic effects. However, cell delivery issues have limited their potential application in clinical practice, showing poor survival and engraftment after transplantation. In this work, we hypothesized that the combination of hiPSC-CMs with microparticles (MPs) could enhance long-term cell survival and retention in the heart and consequently improve cardiac repair. CMs were obtained by differentiation of hiPSCs by small-molecule manipulation of the Wnt pathway and adhered to biomimetic poly(lactic-co-glycolic acid) MPs covered with collagen and poly(d-lysine). The potential of the system to support cell survival was analyzed in vitro, demonstrating a 1.70-fold and 1.99-fold increase in cell survival after 1 and 4 days, respectively. The efficacy of the system was tested in a mouse MI model. Interestingly, 2 months after administration, transplanted hiPSC-CMs could be detected in the peri-infarct area. These cells not only maintained the cardiac phenotype but also showed in vivo maturation and signs of electrical coupling. Importantly, cardiac function was significantly improved, which could be attributed to a paracrine effect of cells. These findings suggest that MPs represent an excellent platform for cell delivery in the field of cardiac repair, which could also be translated into an enhancement of the potential of cell-based therapies in other medical applications.