Cell-bound membrane vesicles contain antioxidative proteins and probably have an antioxidative function in cells or a therapeutic potential

The components and functions of cell-bound membrane vesicles (CBMVs) remain unknown. Here, individual CBMVs were in situ isolated from endothelial cells for investigation of CBMV components/functions. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) detected many antioxidative proteins including the peroxiredoxin (PRDX) family members in isolated CBMVs, which were confirmed by western blotting of some proteins from isolated CBMVs and by immunofluorescence imaging of selected proteins on cells. Then, differ-entially expressed proteins were identified in isolated CBMVs from cells under oxidative stress induced by oxidized low-density lipoprotein (oxLDL), revealing the significant up-regulation of antioxidative proteins (e.g. PRDXs) in isolated CBMVs and the involvement of antioxidative proteins including PRDXs in the protein-protein interaction (PPI) network. Next, single-vesicle tracking was performed on living cells treated with H2O2 responsible for the oxLDL-induced oxidative stress. It was found that a short-term H2O2 treatment caused a concentration-dependent significant decrease in CBMVs motion. Finally, the cells pre-treated with isolated CBMVs were subjected to H2O2 treatment for a relatively long term. We revealed that isolated CBMVs could inhibit the H2O2-induced cell death in a concentration-dependent manner. The data imply that CBMVs contain antioxidative proteins (particularly PRDXs) and potentially play an antioxidative role in cells, which may enable CBMVs to have a therapeutic potential (e.g., as a drug carrier).