局灶性脑缺血后室管膜/室下区细胞迁移到梗塞区周围并分化为神经元和星形胶质细胞

目的研究局灶性脑缺血后室管膜/室下区细胞的迁移分化,揭示梗塞区周围新生细胞的来源.方法大脑中动脉阻塞前,将10μl 0.2%的荧光染料DiI注射于体质量250～350 g的雄性SD大鼠侧脑室以预标记室管膜/室下区细胞.脑缺血后,采用累积式的BrdU标记方法标记新生细胞并通过双重免疫荧光染色确定细胞分化.标记的细胞通过激光共聚焦显微镜观察.结果在非缺血对照大鼠,DiI标记细胞定居于室管膜/室下区.局灶性脑缺血后,DiI标记细胞出现于胼胝体,邻近的纹状体和皮质.此外,缺血14 d后,梗塞区周围纹状体和皮质内可见一些DiI/BrdU/GFAP或DiI/BrdU/NeuN三重标记阳性细胞.结论局灶性脑缺血后,室管膜/室下区细胞迁移到梗塞区周围并分化成神经元和星形胶质细胞,这一发现对于理解成体神经干细胞的起源和开发促进脑损伤后内源性神经发生的新措施具有重要意义.

Ependymal/subventricular zone cells migrate to the peri-infarct region and differentiate into neurons and astrocytes after focal cerebral ischemia in adult rats

OBJECTIVE: To investigate the migration and differentiation of ependymal/subventricular zone cells after focal cerebral ischemia in rats, and reveal the origin of the newly generated neural cells in the peri-infarct region. METHODS: Normal adult male Sprague Dawley rats weighing 250-350 g were used in this study. Before middle cerebral artery occlusion (MCAO), 10 microl of 0.2% DiI was injected into the lateral ventricle for prelabeling the ependymal/subventricular zone cells. After ischemia, cumulative BrdU labeling was employed to detect the newly generated cells and double immunofluorescent staining to identify cell differentiation. The labeled cells were observed with laser confocal microscopy. RESULTS: In the non-ischemic control rats, DiI-labeled cells resided in the ependyma/subventricular zone. After focal cerebral ischemia, DiI-labeled cells were found in the corpus callosum, adjacent striatum and cortex, and some DiI/BrdU/glial fibrillary acidic protein (GFAP)-positive cells or DiI/BrdU/ neuronal nuclear antigen (NeuN)-positive cells were observed in the peri-infarct region in the striatum or cortex since day 14 after MCAO. CONCLUSION: After focal cerebral ischemia, ependymal/subventricular zone cells migrate into the peri-infarct region where they differentiate into neurons and astrocytes. This finding may be important for understanding the source of adult neural stem cells and for developing new therapeutic intervention strategy through enhancing endogenous neurogenesis after brain injury.