RÉSUMÉ
BACKGROUND: Bone marrow mesenchymal stem cells improve neurological functional recovery from cerebral infarction, but they are a rare population in the bone marrow with difficulty in cell separation and purification. OBJECTIVE: To investigate the neuroprotective effects and the potential mechanisms of human placenta-derived mesenchymal stem cell transplantation for cerebral infarction in rats. METHODS: Totally 120 rats subjected to middle cerebral artery occlusion were randomized into treatment group and control (n=60 per group). The rats were intravenously treated with human placenta-derived mesenchymal stem cells in the treatment group or the phosphate buffer saline in the control group. Then, a modified neurological severity score was assessed at 1, 3, 7, 14 days post transplantation, and measurement of infarct volume in the ischemic brain was performed using 2,3,5-triphenyltetrazolium chloride staining at 14 days post transplantation. The anti-human specific immunostain for mitochondria in the ischemic brain was performed and the mitochondria-positive cells were counted; TUNEL immunostaining was performed and TUNEL positive cells were counted. ELISA assays for brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) were also performed in the ischemic brain. RESULTS AND CONCLUSION: At 1, 3, 7 and 14 days after treatment, the modified neurological severity score in the treatment group was significantly lower than that in the control group (P < 0.05). At 14 days after treatment, the infarct volume in the treatment group was significantly lower than that in the control group (P < 0.05), only few mitochondria-positive cells were present in the ischemic brain, and the number of TUNEL positive cells in the treatment group was significantly less than that in the control group (P < 0.05). At 3 and 14 days after treatment, BDNF expression levels in the treatment group were significantly higher than those in the control group (P < 0.05). At 7 and 14 days after treatment, VEGF expression levels in the treatment group were significantly higher than those in the control (P < 0.05). At 7 days after treatment, HGF expression level in the treatment group was significantly higher than that in the control group (P < 0.05). To conclude, intravenous administration of human placenta-derived mesenchymal stem cells can promote neuroprotective effects against cerebral infarction. These effects may be related to the increase of BDNF, VEGF and HGF expression and the decrease of apoptosis in the ischemic brain.