静脉移植骨髓基质干细胞对脑缺血大鼠神经功能及神经细胞凋亡的影响

目的： 探讨骨髓基质干细胞静脉移植后进入大鼠局灶性缺血脑内的短期存活情况及其对脑缺血大鼠神经功能的影响。方法: 将BrdU标记大鼠骨髓基质干细胞后，经尾静脉注射到局灶性脑缺血大鼠体内，分别在脑缺血术后1 d、7 d、14 d和28 d通过神经功能评分观察移植后大鼠神经行为学变化情况，通过组织学方法观察移植到脑内的骨髓基质干细胞存活状态和脑内缺血区与非缺血区神经细胞死亡情况，用RT-PCR方法观察到骨髓基质干细胞表达细胞因子及神经营养因子。结果: 骨髓基质干细胞移植组在14 d和28 d大鼠神经功能评分显著低于对照组（P<0.05），神经功能得到明显改善。静脉移植的骨髓基质干细胞在移植的1 d主要分布在损伤侧大脑中动脉周围组织间质中，在第3d沿着损伤侧的下丘脑迁移至海马的CA1(cornu ammonis 1, CA1)区；骨髓基质干细胞移植组大鼠梗死灶周围的死亡细胞在14 d和28 d明显少于对照组（P<0.05）。结论: 经静脉注射移植骨髓基质干细胞能迁移到损伤区并能够明显促进局灶性脑缺血大鼠的神经行为功能恢复；抗凋亡、分泌神经营养因子改善微环境、动员神经干细胞并迁移至缺血区可能是静脉注射骨髓基质干细胞治疗局灶性脑缺血的机制。

Study on changes of neurological function and neuron apoptosis after intravenous administration of bone marrow stromal stem cells for treating permanent focal cerebral ischemia in rats

AIM: To explore the survivorship and the mechanism of the intravenous administration of bone marrow stromal stem cells (BMSCs) for treating permanent focal cerebral ischemia in rats. METHODS: After purified, proliferated, and marked with BrdU, the BMSCs were injected intravenously into rats 1 d after focal cerebral ischemia.Modified neurological severity score (mNSS) was evaluated before and following 1, 7, 14 and 28 d after middle cerebral artery occlusion (MCAO). Rats were executed at 1, 7, 14 and 28 d after MCAO. Brain sections were stained with hematoxylin and eosin (HE) for determining the infarct volume. Slides were stained by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) and immunostaining for cleaved caspase-3 method for apoptosis detection and mechanism exploration in situ. RESULTS: mNSS in BMSCs-transplanted group at 14th day and 28th day of MCAO was significantly lower than that in control group(P<0.05). TUNEL-positive cells in the hippocampus and thalamus area of BMSCs-transplanted rats were significantly fewer than those in control rats at 14th day and 28th day of MCAO(P<0.05). Double immunostaining showed that small grafted BMSCs and small endogenous neural cell apoptosis depended on the capase-3 in hippocampus. CONCLUSION: The intravenous administration of BMSCs promotes the recovery of neurological function of rats with focal cerebral ischemia. The therapeutic effect of BMSCs on rats with focal cerebral ischemia may be derived from the reduction of apoptosis and the mobility and migration of endogenous neural stem cells in the ischemic boundary zone.