转基因小鼠脊髓损伤后室管膜细胞的时空动态变化

Spatiotemporal dynamic changes of ependymal cells after spinal cord injury in transgenic mice

背景:成年哺乳动物脊髓室管膜细胞损伤后表现出干/祖细胞特性。目的:利用Nestin和Foxj1转基因小鼠标记室管膜细胞,以便追踪室管膜细胞及其子代在成年小鼠脊髓损伤后的增殖分化命运。方法:对转基因小鼠T_(8)脊髓节段完全切除1 mm脊髓组织,术后1-7 d连续腹腔注射BrdU动态观察室管膜细胞,在脊髓损伤后不同时间点(3,7,14,28,56 d)借助BrdU,GFAP,Tuj1,NeuN免疫荧光染色,观察损伤区边缘室管膜细胞的遗传命运谱。结果与结论:①未损伤脊髓中,Nestin阳性的室管膜细胞处于静止状态;脊髓损伤后室管膜细胞被激活,第3天时在损伤区周围大量增殖;②在损伤后第28天,约3.3%Nestin阳性的室管膜细胞表达神经元标记物Tuj1;③在损伤后第56天,约25.7%Nestin阳性的室管膜细胞分化为星形胶质细胞并构成胶质瘢痕的核心,参与胶质瘢痕的形成;④通过检测室管膜细胞在脊髓损伤后的时空动态变化、增殖和分化特征,为理解脊髓损伤的病理过程提供理论依据,为脊髓损伤修复提供新的思路。

BACKGROUND:Spinal cord ependymal cells exhibit neural stem/progenitor cell properties after injury in adult mammalian.OBJECTIVE:Ependymal cells were labeled with Nestin and Foxj1 transgenic mice to track the proliferation and differentiation fate of ependymal cells and their progeny after spinal cord injury in adult mice.METHODS:A 1-mm section was completely removed from the T_(8)segment of the spinal cord in transgenic mice.Ependymal cells were dynamically observed by continuous intraperitoneal injection of BrdU at 1-7 days after spinal cord injury.At different time points(3,7,14,28,56 days)after spinal cord injury,the genetic fate mapping of ependymal cells in the lesion edge was observed by immunofluorescence staining of BrdU,GFAP,Tuj1,and NeuN.RESULTS AND CONCLUSION:(1)In the uninjured spinal cord,Nestin-positive ependymal cells were quiescent.Ependymal cells were activated and proliferated around the lesion edge at 3 days after spinal cord injury.(2)Approximately 3.3%of Nestin-positive ependymal cells expressed neuronal marker Tujl at 28 days after spinal cord injury.(3)At 56 days after injury,approximately 25.7%of Nestin-positive ependymal cells differentiated into astrocytes and formed the core of glial scar,participating in the formation of glial scar.(4)This article can provide theoretical basis for understanding the pathological process and new ideas for spinal cord injury repair by detecting the spatiotemporal changes,proliferation and differentiation characteristics of ependymal cells after spinal cord injury.