Optimizing Extracellular Vesicles for Cardiac Repair Post-Myocardial Infarction: Approaches and Challenges.

Ischemic heart disease remains the leading cause of cardiovascular mortality worldwide. In myocardial infarction (MI), extracellular vesicles (EVs)-particularly small EVs (sEVs)-transport therapeutic cargo such as miR-21-5p, which suppresses apoptosis, and other proteins, lipids, and RNAs that can modulate cell death, inflammation, angiogenesis, and remodeling. This review synthesizes recent mechanistic and preclinical evidence on native and engineered EVs for post-MI repair, mapping therapeutic entry points across the MI timeline (acute injury, inflammation, and healing) and comparing EV sources (stem-cell and non-stem-cell), administration routes, and dosing strategies. We highlight engineering approaches-including surface ligands for cardiac homing, rational cargo loading to enhance potency, and biomaterial depots to prolong myocardial residence-that aim to improve tropism, durability, and efficacy. Manufacturing and analytical considerations are discussed in the context of contemporary guidance, with emphasis on identity, purity, and potency assays, as well as safety, immunogenicity, and pharmacology relevant to cardiac populations. Across small- and large-animal models, EV-based interventions have been associated with reduced infarct/scar burden, enhanced vascularization, and improved ventricular function, with representative preclinical studies reporting approximately 25-45% relative reductions in infarct size in rodent and porcine MI models, despite substantial heterogeneity in EV sources, formulations, and outcome reporting that limits cross-study comparability. We conclude that achieving clinical translation will require standardized cardiac-targeting strategies, validated good manufacturing practice (GMP)-compatible manufacturing platforms, and harmonized potency assays, alongside rigorous, head-to-head preclinical designs, to advance EV-based cardiorepair toward clinical testing.