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脑卒中后缺血组织边界形成胶质疤痕,抑制轴突再生。神经蛋白聚糖是一种轴突延长抑制分子,在卒中后胶质疤痕中表达上调。骨髓基质干细胞(BMSCs)可降低胶质疤痕壁的厚度,加速缺血周边区的轴突重塑。为了进一步明确BMSCs在轴突再生中的作用及机制,本文重点研究脑缺血组织中BMSCs对神经蛋白聚糖表达的作用。31只成年雄性Wistar大鼠大脑中动脉阻塞(MCAo)2 h,24 h后从中选择16只给予尾静脉注射3×106鼠BMSCs(BMSCs组),15只注射磷酸盐缓冲生理盐水(对照组)。缺血后8 d处死实验大鼠,免疫染色表明反应性星形胶质细胞是神经蛋白聚糖的原始来源,且BMSCs组缺血半暗带脑组织的神经聚糖表达明显低于对照组,生长相关蛋白43表达高于对照组,这在蛋白印迹分析中得到确认。为了进一步检测BMSCs在星形胶质细胞神经蛋白聚糖表达中的作用,用激光捕获显微切割法从缺血周边区收集单纯的反应性星形胶质细胞。BMSCs组的神经蛋白聚糖基因表达明显下调(n=4/组)。原代培养的星形胶质细胞也表现出相同改变,糖氧剥离的星形胶质细胞再给氧时与BMSCs共培养会抑制神经蛋白聚糖基因的表达上调(n=3/组)。本研究表明BMSCs通过下调梗死周边星形胶质细胞中神经蛋白聚糖的表达来促进轴突再生。
Stroke ischemic tissue border formation of glial scar, inhibition of axonal regeneration. Neurocan is an axon elongation inhibitory molecule that is upregulated in glial scar after stroke. Bone marrow stromal stem cells (BMSCs) reduce the thickness of the glial scar wall and accelerate axonal remodeling in the ischemic peripheral area. In order to further clarify the role and mechanism of BMSCs in axonal regeneration, this paper focuses on the role of BMSCs on the expression of neurocan in cerebral ischemic tissue. Twenty-one adult male Wistar rats were subjected to occlusion of the middle cerebral artery (MCAo) for 2 h. Twenty-six of them were injected with 3 × 106 BMSCs (BMSCs group) and 15 phosphate buffered saline (control group) . The experimental rats were sacrificed 8 days after ischemia. Immunostaining showed that reactive astrocytes were the original source of neurocan and the expression of neuroglycan in ischemic penumbra of BMSCs group was significantly lower than that of the control group. The expression of growth-associated protein 43 was higher than that of the control group, which was confirmed by Western blot analysis. To further examine the role of BMSCs in the expression of astroglial neurocan, pure reactive astrocytes were collected from the ischemic peripheral area by laser capture microdissection. Neuronal proteoglycan gene expression was significantly down-regulated in the BMSCs group (n = 4 / group). Primary cultures of astrocytes also showed the same changes. Co-culture of stripped astrocytes with oxygen-stripped oxygen inhibited repression of neurocan expression (n = 3 / group). This study shows that BMSCs promote axon regeneration by down-regulating the expression of neural proteoglycan in peripheral astrocytes.