Exosomal preconditioning of human iPSC-derived cardiomyocytes beneficially alter cardiac electrophysiology during hypoxia

Abstract

Abstract Introduction and purpose Cardiac-Exosomes (EXO) are nano-sized extracellular vesicles, continuously secreted by the myocardium. Despite previous misconceptions, cardiac-EXO are not just a way for the cell to dispatch waste, but functions as carriers of signaling molecules. Furthermore, the effects of cardiac-EXO signaling during hypoxic stress is not well understood. The present study aimed to determine the biological effects of EXO released from hypoxic cardiomyocytes, focusing on whether the EXO-cargo can benefit recipient cells during hypoxic stress. We hypothesize that cardiomyocytes exposed to hypoxic stress would display advantageous electrophysiological properties after preconditional treatment with isolated cardiac-EXO secreted from cardiomyocytes exposed to hypoxic stress. Methods For preconditional treatment we isolated EXO from human iPSC-derived cardiomyocytes (CM) exposed to hypoxia (1% O2) for 16 h (H-EXO). H-EXO was thereafter administrated as preconditional treatment to a secondary population of CM 24 h before subjection to 16 h of hypoxia. Electrophysiological effects of H-EXO precondition treatment were assessed with a multiwell microelectrode array (MEA) system. Using the MEA-system; field potential, beat period, spike slope, spike amplitude, excitation-contraction (EC) coupling, and cardiac action potentials were recorded and analyzed. Results We found that CM exposed to hypoxic stress conditions (16 hours) displayed significant increase in beat period when preconditioned with H-EXO compared to non-treated CM (+15.7%, p<0.05). Furthermore, precondition with H-EXO resulted in faster EC coupling compared with non-treated CM after 16 h of hypoxia (-25.3%, p<0.05). More efficient EC coupling indicates that the H-EXO recipient cells are less affected by the hypoxic stress. There were no significant changes in field potential, spike slope, spike amplitude and cardiac action potential between the two groups after 16 h of hypoxia. Conclusion The present study report that EXO secreted by CM under hypoxia alter electrophysiological properties in recipient cells exposed to 16 h hypoxic stress. The alterations indicate more efficient cardiomyocyte EC coupling and longer beat period.