骨髓间充质干细胞可减轻脑卒中缺血周围皮质小胶质细胞过度激活引起的脑损伤

Bone marrow mesenchymal stem cells may alleviate brain damage caused by the microglial overactivation in the cortex around ischemic site of stroke

背景:骨髓间充质干细胞移植治疗缺血性脑卒中取得了较好效果,但其作用机制仍需进行深入研究。目的:探讨骨髓间充质干细胞对缺血周围皮质过度活化的小胶质细胞损伤的影响。方法:将30只8周龄的SD大鼠分为假手术组、模型组、移植组。模型组和移植组采用栓线法阻断大脑中动脉,建立大鼠缺血性脑卒中模型,术后将第3代骨髓间充质干细胞注入到移植组大鼠腹腔内,模型组和假手术组大鼠腹腔内注射相同量的DMEM培养液,各组均隔天注射1次,共持续14 d。术后第7,14天,通过BBB法来评估各组大鼠的运动功能,术后15 d取大鼠脑梗死灶周围皮质并应用免疫组织化学染色法、蛋白印迹法检测活性小胶质细胞标志物Ox-42以及促炎因子肿瘤坏死因子α、白细胞介素6、白细胞介素1β的表达。结果与结论:与假手术组相比,模型组小胶质细胞激活的Ox-42和肿瘤坏死因子α、白细胞介素6、白细胞介素1β表达水平较高,移植组上述指标表达水平较低。与模型组相比,移植组BBB评分明显提高,肢体运动功能有所改善。结果表明,骨髓间充质干细胞抑制梗死灶周围小胶质细胞的过度活化,降低了炎性细胞因子的表达,从而在一定程度上保护了大脑皮质免受伤害,促进了运动功能的恢复。

BACKGROUND:Bone marrow mesenchymal stem cell transplantation has achieved good results in the treatment of ischemic stroke,but its mechanism of action still needs to be studied in depth.OBJECTIVE:To study the effects of bone marrow mesenchymal stem cells on further damage of overactivated microglia in the cortex around ischemic site.METHODS:Thirty 8-week-old Sprague-Dawley rats were divided into sham operation,model,and transplantation groups.The ischemic stroke models of rats were established with blocking the middle cerebral artery with an embolic thread method for the model group and transplantation group.The third generation of bone marrow mesenchymal stem cells was injected into the abdominal cavity of the transplantation.Rabbits of the model group and the sham operation group were injected with the same amount of DMEM.The injection was taken on every other day after surgery for 14 consecutive days.The motor function of paralyzed rats in different groups was evaluated by BBB scores at 7 and 14 days after surgery.At 15 days after operation,the cortex around the cerebral infarction was taken from the rats.Immunohistochemical staining and western blot assay were applied to study the expression of Ox-42,a marker of activated microglia,and tumor necrosis factor-α,interleukin-6,and interleukin-1βin the cortex near the ischemia cortex.RESULTS AND CONCLUSION:Compared with the sham operation group,expression levels of Ox-42 activated by microglia and tumor necrosis factor-α,interleukin-6,and interleukin-1βwere higher in the model group,and decreased in the transplantation group.Compared with the model group,BBB scores showed an improved motor function of paralysis limbs in the transplantation group.It is concluded that the over-activation of microglia is inhibited,and the expression of inflammatory cytokines is decreased with bone marrow mesenchymal stem cells,thus to protect the cerebral cortex from damaging and promote motor function recovery to a certain extent.