Effect of human umbilical cord mesenchymal stem cell exosomes on aerobic metabolism of human retinal pigment epithelial cells

Purpose To investigate the effect of exosomes secreted by human umbilical cord mesenchymal stem cells (HUCMSC-Exo) on aerobic metabolism of cobalt chloride (CoCl2)-induced oxidative damage in the human retinal pigment epithelial cell line (ARPE-19), and to explore the protective mechanism of HUCMSC-Exo on oxidative damage in ARPE-19 cells. Methods HUCMSC-Exo were extracted and identified; CCK-8 assay was used to established the oxidative damage mode of ARPE-19 cells induced by CoCl2; JC-1 flow cytometry was used to detect the effects of exosomes with different concentrations (0, 25, 50, or 100 mu g/mL) on the mitochondrial membrane potential (MMP) of oxidatively damaged ARPE-19 cells. The effects of exosomes with different concentrations on the activity of oxidative metabolic enzymes (oxidative respiratory chain complexes I, III, IV, and V) and ATP synthesis in oxidatively damaged ARPE-19 cells were detected by spectrophotometry. Results Under transmission electron microscope, HUCMSC-Exo were round or oval membrane vesicles with diameters of about 40-100 nm. Western blot results showed that HUCMSC-Exo expressed specific marker proteins CD63 and CD81. CCK-8 dates showed that the cell viability of ARPE-19 cells was significantly decreased with increasing CoCl2 concentration, and the concentration of 400 mu mol/L CoCl2 was chosen to be the optimal concentration for oxidative damage. MMP was increased in exosomes intervention group (25, 50 or 100 mu g/mL), and the dates were statistically different from 0 mu g/mL exosome intervention group (P < 0.05). The activities of mitochondrial complexes I, IV, and V in exosomes intervention groups (100 mu g/mL) were higher than those in 0 mu g/mL exosome intervention group. In 50 mu g/mL and 100 mu g/mL exosome intervention group, ATP synthesis was significantly different from the 0 mu g/mL exosome intervention group (P < 0.05). Conclusion HUCMSC-Exo had a certain protective effect on ARPE-19 cells induced by CoCl2 in vitro. The protective mechanism of HUCMSC-Exo on oxidative damage ARPE-19 cells might be through saving its aerobic metabolic function, restoring cell ATP synthesis, and improving the ability of cells to repair damage and deal with the hypoxic environment.