Large Cardiac Muscle Patches Engineered From Human Induced-Pluripotent Stem Cell–Derived Cardiac Cells Improve Recovery From Myocardial Infarction in Swine

Background —Here, we generated human cardiac muscle patches (hCMPs) of clinically relevant dimensions (4 cm × 2 cm × 1.25 mm) by suspending cardiomyocytes, smooth-muscle cells, and endothelial cells that had been differentiated from human induced-pluripotent stem cells (hiPSCs) in a fibrin scaffold and then culturing the construct on a dynamic (rocking) platform. Methods — In vitro assessments of hCMPs suggest maturation in response to dynamic culture stimulation. In vivo assessments were conducted in a porcine model of myocardial infarction (MI). Animal groups included: MI hearts treated with two hCMPs (MI+hCMP, N=13), treated with two cell-free open fibrin patches (MI+OP, n=14), or with neither experimental patches (MI, n=15); a fourth group of animals underwent sham surgery (SHAM, n=8). Cardiac function and infarct size were evaluated by magnetic resonance imaging, arrhythmia incidence by implanted loop recorders, and the engraftment rate by calculation of quantitative PCR measurements of expression of the human Y chromosome. Additional studies examined the myocardial protein expression profile changes and potential mechanisms of action that related with exosomes from the cell patch. Results —The hCMPs began to beat synchronously within 1 day of fabrication, and after 7 days of dynamic culture stimulation, in vitro assessments indicated the mechanisms related to the improvements in electronic mechanical coupling, calcium-handling, and force-generation suggesting a maturation process during the dynamic culture. The engraftment rate was 10.9±1.8% at 4 weeks after the transplantation. The hCMP transplantation was associated with significant improvements in left ventricular (LV) function, infarct size, myocardial wall stress, myocardial hypertrophy, and reduced apoptosis in the peri-scar boarder zone myocardium. hCMP transplantation also reversed some MI-associated changes in sarcomeric regulatory protein phosphorylation. The exosomes released from the hCMP appeared to have cytoprotective properties that improved cardiomyocyte survival. Conclusions —We have fabricated a clinically relevant size of hCMP with trilineage cardiac cells derived from hiPSCs. The hCMP matures in vitro during 7 days of dynamic culture. Transplantation of this type of hCMP results in significantly reduced infarct size and improvements in cardiac function that are associated with reduction in LV wall stress. The hCMP treatment is not associated with significant changes in arrhythmogenicity.