Mitochondria-Rich Extracellular Vesicles Rescue Patient-Specific Cardiomyocytes From Doxorubicin Injury Insights Into the SENECA Trial

BACKGROUND Anthracycline-induced cardiomyopathy (AIC) is a significant source of morbidity and mortality in cancer survivors. The rote of mesenchymat stem cells (MSCs) in treating AIC was evaluated in the SENECA trial, a Phase 1 National Heart, Lung, and Blood Institute-sponsored study, but the mechanisms underpinning efficacy in human tissue need clarification. OBJECTIVES The purpose of this study was to perform an in vitro clinical trial evaluating the efficacy and putative mechanisms of SENECA trial-specific MSCs in treating doxorubicin (DOX) injury, using patient-specific induced pluripotent stem cell-derived cardiomyocytes (iCMs) generated from SENECA patients. METHODS Patient-specific iCMs were injured with 1 mu mol/L DOX for 24 hours, treated with extracellular vesicles (EVs) from MSCs by either cocutture or direct incubation and then assessed for viability and markers of improved cellular physiology. MSC-derived EVs were separated into large extracellular vesicles (L-EVs) (>200 nm) and small EVs (<220nm) using a novel filtration system. RESULTS iCMs cocuttured with MSCs in a transwelt system demonstrated improved iCM viability and attenuated apoptosis. L-EVs but not small EVs recapitulated this therapeutic effect. L-EVs were found to be enriched in mitochondria, which were shown to be taken up by iCMs. iCMs treated with L-EVs demonstrated improved contractility, reactive oxygen species production, ATP production, and mitochondriat biogenesis. Inhibiting L-EV mitochondriat function with 1-methyl-4-phenylpyridinium attenuated efficacy. CONCLUSIONS L-EV-mediated mitochondrial transfer mitigates DOX injury in patient-specific iCMs. Although SENECA was not designed to test MSC efficacy, consistent tendencies toward a positive effect were observed across endpoints. Our results suggest a mechanism by which MSCs may improve cardiovascular performance in AIC independent of regeneration, which could inform future trial design evaluating the therapeutic potential of MSCs. (C) 2021 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.