Objective:To investigate the effects of environment in vitro and in vivo on the differentiation of bone mesenchymal stem cells (MSCs) into neural cells.Methods:①MSCs were labeled with 4

6-diamidino-2-phenylindole (DAPI) and injected into the right brain of the rats(n=6)

which had suffered from middle cerebral artery occlusion(MACO) a day before.Two weeks later

immunofluorescent staining was used to detect the expression of nestin

microtubule-associated protein 2 (MAP-2) and glial fibrillary acidic protein (GFAP).②In vitro

MSCs were cultured with modified neuronal medium(MNM)for 18 hours after being pretreated with 0.5umol/L all-trans retinoid acid (ATRA) for 24 hours.Immunocytochemistry was used to detect the expression of nestin

MAP-2 and GFAP.Results:①After being injected into rats for 2 weeks

MSCs survived in the ischemic areas and a few cells expressed nestin

MAP-2 and GFAP respectively.②In vitro

after ATRA and MNM treatment

the positive percentage of nestin and MAP-2 were (92.3±3.4)% and (89.6±3.3)% respectively

but no expression of GFAP was detected.Conclusion:The different ratio of MSCs differentiating into neural cells suggests that there is difference in the process and mechanism between environment in vitro and in vivo.