| Objective: Cerebrovascular diseases are familiar and frequent disease of nervoussystem . It is difficult that the injured neurons establish normal synaptic contact once again . So they are difficult problems in clinical treatment . In the past several years, it is usually hot spot of study that transplanted cells substitute or restore the injured cerebral tissue . At present ,there are all kinds of cells for transplantation of central nervous system . Mesenchymal stem cells are non-hematogenic stem cells from marrow . Studies find that MSCs can be easily isolated and cultured,and can be used for transplantation without ethical consideration and immune excluded reaction , compared with the other stem cells .Based on those adventages, MSCs are considered to be an attractive therapeutic tool for a lot of central nervous system diseases . MSCs are multipotent adult tissue stem cell with strong multiplication . Studies have approved that MSCs can be induced into neural-like cells in vitro, and differentiate into neurons and astrocytes in vivo after transplantation . Significant recorvery of neurological function was found in rats treated with MSCs . But it did not still verified whether those cells participate in restructure of neural cells or not . In the present study ,rats cerebral ischemia -reperfusion injury modelwas established with suture emboli method. MSCs were transplanted into rats through external carotid artery .To investigave the effect and mechanism of mesenchymal stem cells (MSCs) transplanted for treatment of cerebral ischemia- reperfusion injury in rats.Methods: 84 healthy adult male Sprague-Dawleye rats were divided into shamoperated group,model group,PBS control group and MSCs treated group at random . Sham operated group has 12 rats . Another each group has 24 rats . According to different reperfusion time , each group was divided into four time of 2d, 4d, 6d, 8d each time of sham operated group has 3 rats, each time of another three groups has 6 rats. MSCs were isolated from the bone marrow of SD rats ,cultured in vitro. Rats cerebral ischemia 2 hour-reperfusion injury model was established with suture emboli method. Model group only made rats cerebral ischemia 2 hour- reperfusion injury model. 2X 106 MSCs labeled with Bromodeoxyuridine(Brdu )and the same volume of PBS were transfered into MSCs treated group rats and PBS control group rats respectively through external carotid artery 24 hours later after 2 hours of middle cerebral attery occlusion .Sham operated group only isolate left side vessels and nerves,not plunged suture emboli .The neurological deficits of rats were evaluated at every day after operation. Rats cerebral tissue was obtained at 2d, 4d, 6d, 8d after stroke except sham operated group . Part and area of infarct were investigated by HE dyeing . The distribution of MSCs and the expression of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor(VEGF) were investigated by immunohistochemistry . The apoptosis of the neural cells was examined by terminal deoxyuncleotidyltransferase-mediated dUTP-biotin nick-end labeling(TUNEL).Results: 1. The rats in sham operated group have no neurological deficit . Theneurological deficits of MSCs treated group rats were more improved than model group rats and PBS control group rats(P<0.05).2. Rats cerebral tissue by HE dyeing finding: Shape and structure of nerve cells in sham operated group was normal and not dropsy in stromal. Denaturalization , putrescence and dropsy of nerve cells in MSCs treated group obviously has improved,compared with model group rats and PBS control group. 3.Immunohistochemistry finding:In MSCs treated group ,there were plenty of Brdu positive cells in infracted hemisphere , mainly resided in cerebral cortex , hippocampus and vascular endothelial .But there were a few Brdu positive cells in opposite hemisphere . And some of MSCs were both Brdu(+),BDNF(+)and Brdu(+),VEGF(+)immunoreaction positive. Another three groups have no above positive cells. At the same time,the expression of BDNFand VEGF in MSCs treated group was higher than the other three groups(jP<0.05), respectively reaching the top at 4d. There is not significant difference between model group rats and PBS control group . But there is obvious different ,compared with sham operated group(P<0.05). 4. TUNEL finding : Apoptosic cells in MSCs treated group were less than the other groups (P<0.05).Conclusion: The transplanted MSCs of rats brain could survive,migrate,producekinds of neurotrophic factors,such as VEGF-. BDNF, markedly upregulate expression of VEGF> BDNF,delay neurotrophic factors high expression time ,and reduce apoptosis of nerve cells .Significant recorvery of neurological function and pathologic change was found in rats treated with MSCs compared with control rats. Thus,the therapy of MSCs transplanted into rat brain following cerebral ischemia is effective. It was one of the main protection mechanisms of MSCs by enhancing neurotrophic factors expression that could reduce apoptosis of nerve cells .
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