Abstract 14375: Mitochondria-Containing Extracellular Vesicles Restore Intracellular ATP Production and Promote Viability in Injured Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

Introduction: Mitochondrial dysfunction disrupts the balance between energy supply and demand in the failing heart. A novel therapy that promotes cellular energetics by providing autologous mitochondria enhances LVEF and prevents cardiac remodeling after myocardial injury. Hypothesis: Mitochondria-containing extracellular vesicles restore mitochondrial function of the injured human cardiomyocytes. Methods and Results: Conditioned medium (CM) from induced pluripotent stem cells (iPSCs) and iPSC-derived cardiomyocytes (iCMs) improved viability of cardiomyocytes challenged by hypoxia and reoxygenation. 220-nm filtration of CM abolished the protective effects, suggesting that the medium-size extracellular vesicles (mEVs, 220-400nm) conferred therapeutic factors. Flow cytometric analysis revealed that the iPSC- and iCM-CM contained functional mitochondria-positive EVs (13% and 25%, p<0.05, respectively), which were removed by 220-nm filter (Fig.A). Ultra-centrifugation resulted in purification of these mitochondria-containing mEVs. Mitochondria positivity in the purified mEVs was similar between iPSCs and iCMs. However, the iCM-mEVs showed 8 times more ATP production compared to iPSC-mEVs (p<0.05). Moreover PGC-1α mRNA expression, a key molecule in mitochondrial biogenesis, was markedly increased in iCM-mEVs. Both iPSC- and iCM-mEVs were taken up rapidly by the injured cardiomyocytes and the mitochondria were readily co-localized with the host-mitochondria. Treatment with iCM-vs. iPSC-EVs significantly increased intracellular ATP production and mitochondrial DNA copy number, restoring the viability of hypoxia injured iCMS (p<0.05, Fig.B). Conclusions: EVs-mediated transfer of functional mitochondria enhances mitochondrial biogenesis and cellular energetics to restore the failing iCMs, which may enable precision medicine for the failing heart. [ABSTRACT FROM AUTHOR]