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

Abstract

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 vesicles (EVs)-mediated transfer of autologous mitochondria and their related energy source enhance cardiac function through restoration of myocardial bioenergetics. Methods: Human-induced pluripotent stem cells (iPSCs)-derived cardiomyocytes (iCMs) were employed. iCMs conditioned-medium were 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 1.0×108/mL M-EVs significantly restored the intracellular ATP production and improved contractile profiles of hypoxia-injured iCMs as early as 3-hours after treatment. In contrast, isolated mitochondria that contained 300 times more mitochondrial proteins than 1.0×108/mL M-EVs showed no effect after 24-hours. M-EVs contained mitochondrial biogenesis-related mRNAs, including PGC-1α, which upon transfer activated mitochondrial biogenesis in the recipient iCMs at 24-hours after treatment. Finally, intramyocardial injection of 1.0×108 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 non-mitochondrial 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. CONDENSED ABSTRACT: Mitochondrial dysfunction results in an imbalance between energy supply and demand in mitochondria-related diseases, including heart failure (HF). Currently, no therapeutic enhances intracellular energetic supply. The goal of this study is to establish a preclinical proof-of-concept that extracellular vesicles-mediated transfer of autologous mitochondria confers cardioprotection through restoration of cellular bioenergetics. Mitochondria-rich extracellular vesicles (M-EVs) are secreted from induced-pluripotent stem cell-derived cardiomyocytes. Intramyocardial injection of M-EVs facilitate immediate transfer of their mitochondrial and non-mitochondrial cargo into the injured cardiomyocytes, improving cardiac function in mice myocardial infarction model. This novel approach may provide an effective therapeutic for mitochondria-related diseases.