Mitochondria-Rich Extracellular Vesicles From Autologous Stem Cell-Derived Cardiomyocytes Restore Energetics of Ischemic Myocardiums

BACKGROUND Mitochondrial dysfunction results in an imbalance between energy supply and demand in a failing heart. An innovative therapy that targets the intracellular bioenergetics directly through mitochondria transfer may be necessary. OBJECTIVES The purpose of this study was to establish a preclinical proof-of-concept that extracellular vesicle (EV)-mediated transfer of autologous mitochondria and their related energy source enhance cardiac function through restoration of myocardial bioenergetics. METHODS Human-induced pluripotent stem cell-derived cardiomyocytes (iCMs) were employed. iCM-conditioned medium was ultracentrifuged to collect mitochondria-rich EVs (M-EVs). Therapeutic effects of M-EVs were investigated using in vivo murine myocardial infarction (MI) model. RESULTS Electron microscopy revealed healthy-shaped mitochondria inside M-EVs. Confocal microscopy showed that M-EV-derived mitochondria were transferred into the recipient iCMs and fused with their endogenous mitochondrial networks. Treatment with 1.0 x 10(8)/ml M-EVs significantly restored the intracellular adenosine triphosphate production and improved contractile profiles of hypoxia-injured iCMs as early as 3 h after treatment. In contrast, isolated mitochondria that contained 300x more mitochondrial proteins than 1.0 x 10(8)/ml M-EVs showed no effect after 24 h. M-EVs contained mitochondrial biogenesis-related messenger ribonucleic acids, including proliferator-activated receptor gamma coactivator-1 alpha, which on transfer activated mitochondrial biogenesis in the recipient iCMs at 24 h after treatment. Finally, intramyocardial injection of 1.0 x 10(8) M-EVs demonstrated significantly improved post-MI cardiac function through restoration of bioenergetics and mitochondrial biogenesis. CONCLUSIONS M-EVs facilitated immediate transfer of their mitochondrial and nonmitochondrial cargos, contributing to improved intracellular energetics in vitro. Intramyocardial injection of M-EVs enhanced post-MI cardiac function in vivo. This therapy can be developed as a novel, precision therapeutic for mitochondria-related diseases including heart failure. (C) 2021 by the American College of Cardiology Foundation.