An Exploratory Study of Kinase Activation Profiles in Hypoxic Human Cardiomyocytes Treated with Protective Extracellular Vesicles.

PURPOSE: Myocardial infarction (MI) causes hypoxic cardiomyocyte death, and extracellular vesicles (EVs) offer therapeutic potential. This study aimed to compare kinase activation profiles induced by four human-derived EV types-serum-derived (S-EVs), platelet concentrate-derived (PC-EVs), cardiac stromal cell-derived (CSC-EVs), and bone marrow mesenchymal stromal cell-derived (MSC-EVs)- in hypoxic metabolically matured human iPSC-derived cardiomyocytes (iCMs). METHODS: Metabolically matured human induced pluripotent stem cell-derived cardiomyocytes (iCMs) were exposed to 12-hour hypoxia ± standardized doses of EVs. Kinase activity was profiled using the PamStation platform, and bioinformatic tools (KRSA, UKA, PTM-SEA, KEA3) identified differentially activated kinases. AKT phosphorylation (Ser473) was measured by ELISA. RESULTS: All EVs significantly reduced LDH release versus hypoxia alone (P ≤ 0.0001), with no inter-group differences. Hypoxia globally suppressed kinase activity, while each EV type induced distinct patterns: S-EVs and PC-EVs increased total phosphorylation, whereas CSC-EVs and MSC-EVs further decreased it. Bioinformatics implicated the AKT family in all treatments, but ELISA revealed no change in AKT1/2/3 phosphorylation at Ser473 versus hypoxia controls. CONCLUSION: Despite equivalent cardioprotection, each EV type elicited unique kinase activation profiles, suggesting distinct signaling mechanisms. Kinase activity was not a predictor of protection at the measured time point, highlighting the complexity of EV-mediated pathways.