Aim To investigate the effect of exosomes derived from bone marrod-derived mesenchymal stem cells(BMSCs)on dexamethasone-induced C2C12 muscular canal atrophy.Methods(1)C57BL/6J mouse bone marrow mesenchymal stem cells were isola-ted and cultured by whole bone marrow adhesion meth-od.(2)Extraction and identification of BMSCs EXOs were performed.(3)Myogenic differentiation of C2C12 cells was carried out.(4)The successfully differentia-ted myotubes were divided into the control group(cul-tured in 2％equine serum medium for 48 h),dexam-ethasone group(dexamethasone,DEX,10 μmol·L-1 concentration of DEX interfered with myotubes for 48 h),and exosomes group(exosomes,EXOs,interfered with myotubes for 48 h),exosome inhibitor group(exo-somes extracted from BMSCs after 10 μm GW4869 in-tervention,interfered with myotubes for 48 h).48 h later,the morphology and diameter of muscle tubes were observed and measured by microscope.Cell via-bility of each group was detected by CCK-8 method.The expression levels of atrogin-1 and MuRF-1,myo-genic differentiation antigen(MYOD)in each group were detected by Western blot.Results BMSCs were long spusiform,and BMSCS-EXOS showed a circular bilayer structure under transmission electron microsco-py,with a diameter of about 200 nm.CD9,CD63 and CD81 were highly expressed.Compared with the con-trol group,cell activity in DEX group decreased(P＜0.01),diameter of myotubes decreased(P＜0.01),expressions of atrogin-1(P＜0.05)and MuRF-1(P＜0.01)were significantly up-regulated,and expression of MYOD(P＜0.01)was significantly down-regula-ted.Compared with the DEX group,cell activity in the BMSCs-EXOs group increased(P＜0.01),diameter of myotubes increased(P＜0.01),expressions of atrogin-1(P＜0.05)and MuRF-1(P＜0.01)were signifi-cantly down-regulated,and expression of MYOD(P＜0.01)was up-regulated.Compared with the BMSCs-EXOs group,cell activity of the BMSCs-EXOs(GW4869)group decreased(P＜0.05),diameter of myotubes decreased(P＜0.01),expressions of atrog-in-1(P＜0.05)and MuRF-1(P＜0.05)were up-regulated,and expression of MYOD(P＜0.01)was down-regulated.Conclusion Bone marrow mesen-chymal stem cell-derived exosomes(BM-MSCs-EXOs)inhibit dexamethasone-induced C2C12 muscle tube at-rophy.

Aim To investigate the effect of exosomes derived from bone marrod-derived mesenchymal stem cells(BMSCs)on dexamethasone-induced C2C12 muscular canal atrophy.Methods(1)C57BL/6J mouse bone marrow mesenchymal stem cells were isola-ted and cultured by whole bone marrow adhesion meth-od.(2)Extraction and identification of BMSCs EXOs were performed.(3)Myogenic differentiation of C2C12 cells was carried out.(4)The successfully differentia-ted myotubes were divided into the control group(cul-tured in 2％equine serum medium for 48 h),dexam-ethasone group(dexamethasone,DEX,10 μmol·L-1 concentration of DEX interfered with myotubes for 48 h),and exosomes group(exosomes,EXOs,interfered with myotubes for 48 h),exosome inhibitor group(exo-somes extracted from BMSCs after 10 μm GW4869 in-tervention,interfered with myotubes for 48 h).48 h later,the morphology and diameter of muscle tubes were observed and measured by microscope.Cell via-bility of each group was detected by CCK-8 method.The expression levels of atrogin-1 and MuRF-1,myo-genic differentiation antigen(MYOD)in each group were detected by Western blot.Results BMSCs were long spusiform,and BMSCS-EXOS showed a circular bilayer structure under transmission electron microsco-py,with a diameter of about 200 nm.CD9,CD63 and CD81 were highly expressed.Compared with the con-trol group,cell activity in DEX group decreased(P＜0.01),diameter of myotubes decreased(P＜0.01),expressions of atrogin-1(P＜0.05)and MuRF-1(P＜0.01)were significantly up-regulated,and expression of MYOD(P＜0.01)was significantly down-regula-ted.Compared with the DEX group,cell activity in the BMSCs-EXOs group increased(P＜0.01),diameter of myotubes increased(P＜0.01),expressions of atrogin-1(P＜0.05)and MuRF-1(P＜0.01)were signifi-cantly down-regulated,and expression of MYOD(P＜0.01)was up-regulated.Compared with the BMSCs-EXOs group,cell activity of the BMSCs-EXOs(GW4869)group decreased(P＜0.05),diameter of myotubes decreased(P＜0.01),expressions of atrog-in-1(P＜0.05)and MuRF-1(P＜0.05)were up-regulated,and expression of MYOD(P＜0.01)was down-regulated.Conclusion Bone marrow mesen-chymal stem cell-derived exosomes(BM-MSCs-EXOs)inhibit dexamethasone-induced C2C12 muscle tube at-rophy.