Abstract: Objective To observe therapeutic effect of bone marrow mesenchymal stem cells(BMSCs)via vein intravenous transplantation on cerebral infarction and its influence on expressions apoptosis-related proteins.Methods The rat bone marrow mesenchymal stem cells were isolated and purified with whole bone marrow culture in vitro, and marked with 5-bromodeoxyuridine(BrdU).The permanent middle cerebral artery occlusion(MCAO)model was established using modified Zea Longa method in 45 Sprague-Dawley(SD)rats and then the rats were randomly divided into three groups equally:an experimental group with 1 ml BMSCs suspension via caudal vein injection, a control group with 1 mL saline injection, and a blank group without injection.The rats in the 3 groups were assessed with modified neurological severity score(mNSS)at the day of the establishment of cerebral infarction, the 3rd and 7th day of BMSCs transportation.Triphenyl tetrazolium chloride(TTC)staining was used to detect the cerebral infarction volume;immunohistochemical method and Western blot were adopted to detect BrdU positive cells and expressions of Bcl-2, caspase-3 protein in the brain tissues at the 7th day of BMSCs transportation.Results The result of mNSS showed that the score of cell transplantation group was significantly lower than that of the control group(P<0.01), but there was no statistically significant difference in the score between the blank and control group(P>0.05).TTC staining showed that compared with the control group, the cerebral infarction volume of BMSCs transplantation group was significantly reduced(P<0.05), but there was no statistically significant difference in the score between the blank and control group(P>0.05).BrdU positive cells were observed in infarction area of BMSCs transportation rats.The results of both immunohistochemistry and Western blot showed that compared with the control group, the expression of Bcl-2 in BMSCs transplantation group was increased significantly(all P<0.01), while the expression of caspase-3 was decreased significantly(all P<0.05).There were no statistically significant differences in the expression between blank and control group(P>0.05).Conclusion BMSCs vein transplantation could improve function of neural cells in the rats with cerebral infarction and the effect is related to the inhibition of cerebral cell apoptosis.