Abstract Body: Introduction: Cardiovascular diseases are the leading cause of mortality worldwide. After myocardial infarction (MI), there is a permanent loss of cardiomyocytes (CMs), and as the mammalian heart has limited regenerative capacity, it leads to Heart Failure. Extracellular vesicles (EVs) derived from induced pluripotent stem cells (iPSCs) have emerged as potential therapeutic agents, yet their precise mechanism of CM survival and cardiac repair remains elusive.

Hypothesis: The myocardial delivery of hiPSC-EV-specific protein improves cardiac function and mice survival post-MI by inhibiting CM apoptosis and oxidative stress molecular pathways.

Methods and Results: Our preliminary studies confirmed that hiPSC-EVs promote CM survival post-MI in mice, and through proteomic analysis, we identified a novel protein uniquely expressed in hiPSC-EVs. We showed that the myocardial delivery of hiPSC-EVs specific protein in the form of modRNA inhibited CM apoptosis and induced CM survival post-MI. This increase in the CM's survival by hiPSC-EVs specific protein expression was associated with reduced scar size, improved cardiac function, and mice survival 28 days post-MI. Furthermore, using the siRNA and small molecule inhibition of hiPSC-EVs specific protein, we found enhanced MI-induced CM apoptosis post-MI. Mechanistic insights reveal the hiPSC-EVs specific protein induced STAT3 pathway, while STAT3 pathway inhibition by small molecule repressed hiPSC-EVs specific protein induced CM survival in vitro. Additionally, our preliminary study shows this protein translocates to the nucleus post-MI or ischemic injury.

Conclusion: Taken together, the myocardial injection of hiPSC-EVs specific protein through a highly therapeutic modRNA tool improves cardiac function by inhibiting CMs apoptosis, and reactivating cardiac repair post-injury. Moreover, our studies demonstrate that the modRNA (protein) approach in mouse models is potentially adaptable for mRNA therapeutics in a clinical setup.