Extracellular vesicles in post-infarction diabetic hearts

Introduction Cardiovascular disease (CVD) is the main cause of death in non-communicable diseases. In response to myocardial infarction (MI), extracellular vesicles (EVs), large (lEVs) and small (sEVs), are released within and from the heart to facilitate intercellular communication and maintain cardiac homeostasis, transferring their content such as miRNA, to recipient cells. Objective As diabetes increases the risk of CVD, the objective was to investigate how diabetes influences the release of cardiac EVs post-MI and to determine EV miRNA content. Methods B6J mice were fed chow diet or high-fat diet (HFD) for 3 months and subjected to MI by permanent ligation of the left anterior descending artery. Left ventricles were harvested at different timepoints post-MI and processed for EV extraction by differential centrifugation. EVs were analysed by Tunable Resistive Pulse Sensing (TRPS), flow cytometry and Western blot (WB). RNA sequencing of cardiac EVs was performed to reveal miRNAs of interest that were upregulated in cardiac EVs of MI mice and validated in HFD mice. Results In control mice, release of both lEVs and sEVs was increased at 24 h and 7 d post-MI. Similarly, in HFD mice, lEVs peaked at 24 h and 7 d post-MI and this increase was greater than in chow diet mice but there were no differences in sEV release between sham and MI HFD mice. TRPS analysis revealed that diabetes does not change EV size and flow cytometry showed that they are mainly of cardiomyocyte origin. Furthermore, EVs harboured cardiomyocyte marker (Troponin T) and sEVs carried tetraspanin markers as revealed by WB. Different miRNAs were also found to be upregulated in lEVs and sEVs in MI mice. Conclusion Our results show that diabetes modulates the release of both cardiac lEVs and sEVs post-MI. Furthermore, there is a difference in miRNA content between the 2 types of EVs post-MI. Further work is needed to investigate the functional impact of cardiac EVs in the diabetic heart post-MI.