Serum Extracellular Vesicles Attenuate Cardiomyocyte Injury Induced by Hypoxic/Reoxygenation by Regulating miR-1229-5p

Ischemic heart disease and the resulting heart failure remain the leading causes of death and disability worldwide. This study aimed to investigate the role of miR-1229-5p in serum extracellular vesicles (EVs) mediated myocardial protection by constructing a hypoxia/reoxygenation model (HR) in H9c2 cells. Cardiomyocytes were cultured and divided into different treatment groups: control group, HR group, serum-EVs group, and serum-EVs + miR-1229-5p inhibitor group. The expression levels of miR-1229-5p were detected using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The changes in cell proliferation and apoptosis were detected by MTT assay and flow cytometry. The myocardial injury-related indicators, cardiac troponin I (cTnI), creatinine kinase MB (CK-MB), and lactate dehydrogenase (LDH), were measured by enzyme-linked immunosorbent assay (ELISA). Finally, the luciferase reporter assay was used to verify the miR-1229-5p target. The proliferation of myocardial cells in the HR group was reduced, the number of apoptotic cells was increased, and myocardial injury indicators concentration was decreased. Transfection of miR-1229-5p inhibitor under serum-EVs treatment reduced the protective effect of serum-EVs on myocardial cell injury, decreased cell proliferation, increased the number of apoptotic cells, and increased myocardial injury indicator concentration. Additionally, FOXO4 may be the target of miR-1229-5p. Our data suggest that serum-EVs alleviate HR-induced cardiomyocyte injury by regulating miR-1229-5p/FOXO4.