Extracellular vesicles from melatonin-preconditioned mesenchymal stromal cells protect human umbilical vein endothelial cells against hypoxia/reoxygenation detected by UHPLC-QE-MS/MS untargeted metabolic profiling.

Myocardial ischemia-reperfusion injury (MIRI), which occurs when the blood supply is restored in the ischemic myocardium, is a major medical concern for patients with acute myocardial infarction (AMI). Despite the use of extracellular vesicles (EVs) from mesenchymal stromal cells (MSCs), which can be used to treat MIRI, the application of EVs still has limited use in clinical practice. Melatonin (MT), however, not only exerts a significant protective effect in the treatment of cardiovascular diseases but also enhances biological functions of MSCs through pretreatment. Therefore, in the current study, we sought to determine whether MT improves the paracrine effect of MSCs through pretreatment. Our research provides evidence to support the therapeutic effect of MT-pretreated MSCs-derived extracellular vesicles (MT-EVs) in ameliorating hypoxia/reoxygenation (H/R) injury in human umbilical vein endothelial cells (HuVECs). We also performed a metabolomic analysis using ultra-high-performance liquid chromatography/Q Exactive HF-X Hybrid Quadrupole-Orbitrap Mass (UHPLC-QE-MS/MS) to explore metabolism profiling of H/R cell model with MT-EVs or EVs from MSCs (NC-EVs) treatment. We found 932 differential metabolites (DEMs) in the MT-EVs group compared with the NC-EVs group. Metabolic profiling analysis showed these metabolites were engaged in the ABC transporters, nucleotide metabolism, purine metabolic pathway, and glycerophospholipid metabolism. Furthermore, we observed increased levels of palmitoylcarnitine (fatty acid-derived mitochondrial substrate) and gabapentin in the MT-EVs group, which may play a therapeutic role in HuVECs during H/R. In conclusion, the results demonstrated that MT-EVs can protect endothelial cells from H/R injury by affecting the metabolic pathways.