Patching the scarred heart

Acute myocardial infarction (AMI) and heart failure (HF) that often follows remain the leading causes of morbidity and mortality worldwide. Following MI, lost cardiomyocytes (CM) are replaced by non-contractile scar tissue that increases ventricular wall stress while diminishing myocardial performance. With the negligible regenerative capacity of the heart, the field of heart engineering and regenerative therapy for MI remains a challenge. Cardiac patch often combines the use of cells and synthetic/biomaterials with the ultimate aim of improving myocardial function. Through the years, there have been remarkable breakthroughs in the fields of stem cell and biomaterials research. The advent of human-induced pluripotent stem cells provides a potentially unlimited source of cardiomyocytes for regenerative therapy. By combining this with 3D bioprinting, it was possible to generate a cardiac patch with cell and structural organizations similar to that of the native heart. Even with vast technological advancements, the promise of the cardiac patch to treat MI has not been fulfilled. Subsequent studies revealed that exosomes, rather than the cellular component of the cardiac patch, is one of the main contributors to its cardioprotection. In this review, we present and discuss perspectives of the cardiac patch and its drawbacks and future relevance as a promising intervention for MI patients.