Mitochondrial Transplantation Augments the Reparative Capacity of Macrophages Following Myocardial Injury

The pathologically remodeled myocardial ischemic microenvironment, characterized by sustained hypoxia, metabolic insufficiency, and accumulation of inflammatory mediators, severely disrupts mitochondrial homeostasis. This dysfunction establishes a self-perpetuating cycle that impairs the coordinated healing cascade and compromises cardiac tissue repair following myocardial infarction (MI). To counteract these effects, a novel strategy of mitochondrial augmentation is proposed, whereby healthy exogenous mitochondria are introduced into macrophages to generate mitochondria-transplanted macrophages (Mito-T-Macros or MTMs), which can resist post-MI stress. Mitochondrial transplantation (MT) effectively induces macrophage polarization toward a reparative M2-like phenotype, thereby enhancing pro-healing functions, including migration, invasion, and phagocytosis. In vivo, MTM therapy enhances cardiac function after MI and attenuates left ventricular remodeling by reducing fibrosis, limiting apoptosis, and promoting angiogenesis. Mechanistically, MT accelerates the phenotypic transition of macrophages to a reparative state and prolongs their activity during the healing phase. Notably, a portion of the transplanted mitochondria are released from MTMs and subsequently internalized by cardiomyocytes, suggesting an additional mechanism of myocardial support. Overall, MT enhances the reparative capabilities of macrophages and contributes to the therapeutic efficacy of MTMs in ameliorating post-MI cardiac remodeling. These findings support MTM therapy as a promising and innovative approach for repairing myocardial injury following MI.