Abstract: 【ABSTRACT】: Objective: To explore the protective effect of Marrow Stem Cells (MSCs) derived exosomes on PC12 injured by hydrogen peroxide in rats after intervention by BDNF. Methods: Rat MSCs were extracted by whole bone marrow adherent culture methods. The supernatant of cells was collected by adding BDNF into part of the medium for P3 generation and supernatant was also collected without BDNF intervention. Exosomes were isolated and purified by ultracentrifugation, and their morphology was observed and identified under transmission electron microscopy. Western blotting was used to verified the surface marker proteins CD9 and CD63. PC12 cells were divided into control group, simple injured group, MSCs exosome group, BDNF-MSCs exosome group. PBS was added to the medium of the first two groups, and corresponding exosomes (exosome protein concentration 50 microns /ml) were added to the latter two groups to pretreat them for 12h, and the last 3 groups were established cell damage models of oxidative stress by H2O2 on PC12. 10h later cell viability was detected by CCK8 method, ROS activity and SOD value were detected by kit, and Bcl-2 and Bax protein expression were detected by Western Blotting. Result: CD90 expression on the cell surface of P3 generation MSCs was positive. Exosomes were successfully extracted , a large number of irregular spheres or saucer-shaped vesicles with diameters of 40-100 nm were observed under transmission electron microscopy. The membranes were clear and relatively complete, and CD9 and CD63 proteins were positively expressed by Western Blot. Compared with simple injured group and MSCs exosome group, BDNF-MSCs exosome group had the highest cell viability, the highest SOD activity, the lowest ROS and the highest bcl-2 /Bax value. Conclusion: The protective effect of MSCs-derived exosomes after intervention by BDNF on oxidative stress injury induced by H2O2 on PC12 was better than that of MSCs-derived exosomes.

Key words: exosome, MSCs, PC12, oxidative stress