脂肪间充质干细胞外泌体对脑创伤记忆障碍作用及机制研究

Effect and mechanism of adipose mesenchymal stem cell exosomes on memory impairment after brain trauma

目的 探讨脂肪间充质干细胞外泌体对脑创伤记忆障碍的作用及机制。方法 采用差速离心法提取脂肪间充质干细胞外泌体。将24只SD大鼠随机分为对照组、脑创伤组、外泌体组,每组各8只。对照组大鼠不作处理,脑创伤组、外泌体组大鼠采用落体撞击法建立脑创伤模型,外泌体组在模型建立成功后静脉注射脂肪间充质干细胞外泌体300μg。7 d后,通过水迷宫评价大鼠记忆能力,通过湿干重、Tau和S100β蛋白评价脑组织损伤及修复情况。采用酶联免疫吸附法检测大鼠脑组织神经生长因子(NGF)和脑源性神经营养因子(BDNF)的表达。采用蛋白免疫印迹法检测大鼠脑组织TrkA和TrkB蛋白表达。结果 脑创伤组大鼠湿干比、Tau和S100β蛋白表达水平高于对照组,差异均有统计学意义(P<0.05);外泌体组大鼠湿干比、Tau和S100β蛋白表达水平低于脑创伤组,差异均有统计学意义(P<0.05)。与脑创伤组比较,外泌体组大鼠第2~5天逃避潜伏期缩短,穿越平台次数增加,目标象限时间延长,脑组织NGF、BDNF、TrkA和TrkB蛋白表达升高,差异均有统计学意义(P<0.05)。结论 脂肪间充质干细胞外泌体能够减轻脑创伤后记忆障碍,其机制与调节神经营养因子及TrkA/TrkB受体有关。

Objective To investigate the effect and mechanism of adipose mesenchymal stem cell exosomes on memory impairment after brain trauma.Methods Extraction of adipose mesenchymal stem cell exosomes by differential centrifugation.A total of 24 SD rats were randomly divided into control group,brain trauma group and exosome group,with 8 rats in each group.The rats in the control group were not treated,the brain trauma model of rats in the brain trauma group and exosome group was established by falling body impact method,and the exosome group was injected 300 μg of adipose mesenchymal stem cell exosomes intravenously after the model was established.After 7 days,the memory ability of rats was evaluated by water maze,and the damage and repair of brain tissue were evaluated by wet and dry weight,Tau and S100β proteins.The expressions of nerve growth factor(NGF) and brain-derived neurotrophic factors(BDNF) in rat brain were detected by enzyme-linked immunosorbent assay.The expression of TrkA and TrkB in rat brain was detected by Western blot.Results The wet-dry ratio,Tau and S100β protein expression levels in brain trauma group were higher than those in control group,and the differences were statistically significant(P<0.05).The wet-dry ratio,Tau and S100β protein expression levels in exosome group were lower than those in brain trauma group,and the differences were statistically significant(P<0.05).Compared with the brain trauma group,the escape latency of rats in the exosome group was significantly shortened from day 2 to 5,the frequency of crossing the platform was significantly increased,the target quadrant time was prolonged,the expression of NGF and BDNF in brain tissue was significantly increased,and the protein expressions of TrkA and TrkB were increased,with statistical significance(P<0.05).Conclusion Adipose mesenchymal stem cell exosomes can alleviate post-traumatic memory impairment,and the mechanism is related to the regulation of neurotrophic factors and TrkA/TrkB receptors.