骨髓间充质干细胞旁分泌作用与脑缺血后的细胞凋亡*

背景：骨髓间充质干细胞移植治疗脑缺血的机制之一是骨髓间充质干细胞的旁分泌作用，而目前对于这一机制的研究报道较少。目的：观察骨髓间充质干细胞旁分泌作用对脑缺血后细胞凋亡的抑制作用并探索相关机制。方法：体外培养大鼠骨髓间充质干细胞，建立大鼠大脑中动脉缺血模型。24只SD大鼠随机数字表法分为4组，每组6只。细胞移植给药组：大鼠纹状体内移植骨髓间充质干细胞后给予ERK1/2抑制剂U0126；非移植给药组：注射等量的PBS后给予U0126；细胞移植对照组：移植骨髓间充质干细胞后给予溶剂对照；非移植对照组：注射等量的PBS后给予溶剂对照。7 d后通过Western blot检测血管内皮细胞生长因子、磷酸化ERK1/2蛋白的表达；TUNEL染色检测梗死区周围及皮质区细胞凋亡情况。结果与结论：细胞移植组较非移植组大鼠纹状体内血管内皮细胞生长因子蛋白的表达明显增高，磷酸化ERK1/2表达增强，细胞凋亡数明显减少；经U0126处理后，血管内皮细胞生长因子的表达没有变化，而随着磷酸化ERK1/2的表达受到抑制，细胞凋亡数明显增高。提示骨髓间充质干细胞在大脑纹状体内可以旁分泌血管内皮细胞生长因子，并通过激活ERK1/2抑制了脑梗死区细胞的凋亡。

Paracrine action of bone marrow mesenchymal stem cells and cell apoptosis following cerebral ischemia

BACKGROUND: One of mechanisms involved in treating cerebral ischemia with bone marrow mesenchymal stem cells (BMMSCs) implantation is paracrine action. However, few studies have reported this mechanism.OBJECTIVE: To observe the inhibitory effect of BMMSCs paracrine action on apoptosis and its mechanism after cerebral ischemia. METHODS: BMMSCs were isolated from rats with adherent culture. Rat cerebral ischemia model was established by the middle cerebral artery occlusion. A total of 24 rats were divided into 4 groups, with 6 animals in each group. Cell implantation medication group: rats were received U0126 medication after BMMSCs implantation; Non-implantation medication group: rats were received U0126 medication after PBS injection; Cell implantation control group: received solvent medication after BMMSCs implantation; Non-implantation control group: received solvent medication after PBS injection. At 7 days after operation, the expressions of vascular endothelial cell growth factor (VEGF) and p-ERK1/2 protein were measured by Western blot analysis, and the apoptosis cells in the area of ischemic penumbra and cortex were examined by TUNEL. RESULTS AND CONCLUSION: The VEGF protein content in the brain tissue was significantly greater in the cell implantation groups than that of the non-implantation group, with increased p-ERK1/2 and decreased apoptosis cells. The expression of p-ERK1/2 was down-regulated in rats which were administrated U0126 while the number of the apoptosis cells was increased, but the VEGF protein expression had no statistical difference. It suggested that BMMSCs can paracrine VEGF in the striatum of brain and play an inhibitory effect on apoptosis in the ischemia area via activating ERK1/2.