Experimental Study On Bone Marrow Mesenchymal Stem Cells On Hypoxic-ischemic Brain Damage In Newborn Mice

Objective(s):In this study,a hypoxic-ischemic brain damage(HIBD)model was established in newborn mice,bone marrow mesenchymal stem cells(BMSCs)were transplanted into the brain,to investigate its effect on blood brain barrier(BBB)tight junction protein in mice and its effect on behavior,in order to lay a foundation for the treatment of neonatal hypoxic-ischemic brain injury by mesenchymal stem cells.Methods:10-day-old C57BL/6 mice were randomly divided into four groups,they were sham operation group,hypoxic-ischemic group,placebo group and stem cell group.In the sham operation group,only the skin of the neck was cut and sutured.The other three groups underwent left common carotid artery ligation,then keep in an anoxic chamber containing 8%oxygen and 92%nitrogen for 45min.BMSCs were injected into the left ventricle with a stereotactic device after 24 hours of modeling,cell volume was 5×1.06/ul,5ul each,and the injection time was 5min.7 days after transplantation,the ultrastructure of BBB was observed by trans-mission electron microscopy;The expression of junction protein was detected by western blotting and immunofluorescence;Free suspension test、new object test and open field test etc.which were carried out at 21 days after birth,to investigate the effect of BMSCs on neonatal mice HIBD model.Results:1.Effects of BMSCs on the behavior of neonatal mice with HIBD:1.1 Upper limb motor ability:Free suspension test:Compared with the sham operation group,in the stem cell group,the grasping ability of forelimb was decreased,has statistically significant difference(P<0.05);Compared with the hypoxic-ischemic group and the placebo group,the grasping ability of forelimb was improved,have statistically significant difference(P<0.05).1.2 Cognitive Ability:1.2.1Y maze test:Compare with the control group,in the stem cell group,the residence time and entry times in the new arm was decreased,has statistically significant difference(P<0.05);Compared with the hypoxic-ischemic group and the placebo group,the residence time and entry times in the new arm was increased,there were statistical differences(P<0.05).1.2.2New object test:Compare with the control group,the stem cell group spent less time on new things,more time on old things,object recognition index was decreased,there were statistical differences(P<0.05);Compared with the hypoxic-ischemic group and the placebo group,the stem cell group spent more time on new things,less time on old things,object recognition index was improved,there were statistical differences(P<0.05).1.3 Anxiety and exploratory behavior:Open field test:Compared to the sham group,in the stem cell group,the total distance,duration of stay and number of entries in the central area were all reduced,there were statistical differences(P<0.05);Compared with the hypoxic-ischemic group and the placebo group,duration of stay and number of entries in the central area were increase,there were statistical differences(P<0.05).2.Effects of BMSCs on BBB tight junction in neonatal mice with HIBD:In the sham group,the BBB tight junction in good condition,in the hypoxic-ischemic group and in the placebo group,the BBB tight junction was loosen,endothelial cells show vacuol-like changes,after treatment of BMSCs,the degree of porosity of tight junction was reduced.3.Effect of BMSCs on BBB tight junction protein in newborn mice with HIBD:Compared to the hypoxic-ischemic group and the placebo group,the expressions of claudin-5,occludin and caveolin-1 were increased in the stem cell group,has statistically significant difference(P<0.05).Conclusion(s):1.Newborn mice with HIBD showed that fall in motor ability and cognitive ability and appear anxious behavior,BMSCs treat newborn mice with HIBD,improve motor and cognitive function,reduce anxiety and depressive behavior.2.BMSCs treat newborn mice with HIBD,promoting BBB repair by increasing the expression of tight junction protein.3.BMSCs treat newborn mice with HIBD,improve motor and cognitive function,reduce anxiety and depressive behavior,it may have something to do with promoting BBB repair.