Mesenchymal Stem Cells Transplantation For Treating Middle Cerebral Artery Occlusion In Rats

Objective:To investigate the effect and mechanisms of mesenchymal stem cells stereotaxically transplanted for treating cerebral ischemia in rats and to study the different effect of human and rat mesenchymal stem cells transplantation on rats with middle cerebral artery occlusion.Methods:Bone marrow tissues of human and rats were collected and the MSCs were separated with density gradient centrifugation and screening the cells adherent to the plastic surface. The MSCs were cultivated in specified medium. Before the transplantation,MSCs were treated by basic fibroblast growth factor(bFGF) and labeled by bromodeoxyuridine (BrdU) .SD rat middle cerebral artery occlusion model was established with suture emboli method. General magnetic resonance examination was taken to fix the lesion area of the rats. Forty of them showing the scores of 2-3 according to the neurological deficit score were randomly divided into 5 groups: control group,hMSCs transplantation groups,rMSCs transplantation groups. Transplantation groups included preinductived and uninductived groups .Each group has eight rats. 1×10~6MSCs(preinductived and uninductived)labeled with BrdU were injected into the ischemic striatum through Stereotactic path 7 day later after middle cerebral artery occlusion. MCAO model was made in control group. Rats did not receive immunodepressant. The neurologic severity score (NSS) were performed at choosed days after MCAO . Rats were euthanized at 3 months after transplatation and brain tissue were made paraffin sections. Pathological change were investigated by HE dyeing. Brain tissues sections were prepared for immunohistochemistry staining of 5-bromodeoxyuridine(BrdU), neuron specific enolase (NSE), and glial fibrillary acidic protein (GFAP). Immunohistochemistry was used to identify the level change of brain-derived neurotrophic factor (BDNF).Results:(1) The results showed that by gradient centrifugation and adhesion culture, MSCs could be isolated and culture-expanded. MSCs primary identification can be accomplished by flow cytometry. (2)The rats developed typical symptoms of neurological impairment after they were subjected to MCAO. MRI showed ischemic regions were high signals in DWI.(3)The neurological severity score (NSS) of the rats with MSCs-transplantation groups was significantly lower than the control group (P<0.05). There were no significant difference between hMSCs-transplantation groups and rMSCs-transplantation groups. (4)There were BrdU reactive cells in the transplantation site. BrdU reactive cells expressed the NSE and the GFAP. The BDNF expression in brain tissues of transplantation group was higher than control group(P<0.05).Conclusion:(1)MSCs can be isolated,cultured and expanded in vitro.(2)The suture emboli method was so simple and reliant that it could be used in the study of cerebral ischemia.(3)MSCs Stereotactic transplantation can survived and differentiated into astrocytes and neurons. Transplanted MSCs can enhancing the BDNF expression .(4) MSCs Stereotactic transplantation can promote the recovery of neurological function of rats with focal cerebral ischemia. The therapeutic effect of MSCs on rats with focal cerebral ischemia may be derived from the increase of BDNF expression in the brain tissues.