小鼠血管内皮细胞转化机制研究

Study of musine vascular cells regeneration

目的运用转基因小鼠股动脉的损伤模型模拟临床的血管内膜损伤,通过谱系追踪分析血管损伤后血管重构、血管内皮细胞增生及分化病理机制。方法运用可诱导的内皮细胞特异性标记的转基因小鼠与带有报告基因YFP(黄色荧光蛋白)的小鼠杂交,繁殖出可在诱导剂Tamoxifen注射后,YFP在内皮细胞特异表达的转基因小鼠。并模拟临床静脉移植术,建立小鼠颈静脉-股动脉内膜移植模型,设立术后0h(未损伤)、3、7、14和35d5个时间点。于各时间点取组织进行免疫化学染色和计数观察。结果活体的静脉移植实验中,标记YFP的内皮细胞系细胞逐渐获得平滑肌细胞的特征,而失去内皮细胞的特征。在离体实验中,内皮细胞(EOMA细胞)在TGF-β1诱导4d后同样显示出平滑肌细胞的特性。结论在血管移植后移植血管发生了血管重构,增厚的新生内膜中的内皮细胞转化为平滑肌样细胞。

[Objective] It is very important to study proliferate endothehal cell and smooth muscle cell and mutual relation and morphology during a vascular remodeling, for those are essential vascular cells. To determine the fate of vascular cells during the vascular remodeling. [Methods] We generated a transgenic mouse line, expressing a tamoxifen-inducible Cre recombinase, which is controlled by the vascular cells specific promoter. The transgcnic mice were crossed with mice carrying the yellow fluorescent protein （YFP） controlled by the ubiquitous R26R promoter but with a floxed stop codon in between; in effect, tamoxifen injections resulted in YFP expression exclusively in vascular endothelial cells. We established vascular remodeling murine model, and harvested tissues at the following time points： hour 0, day 3, day 7, day 14 and day 35. [Results] In vascular remodeling model, we found that endothelial-lineage cells lose endothelial markers and gain smooth muscle cells characteristics as they proliferate in the neointima in vivo. The endothelial cells which were treated with TGF-β1 for 4 days gain SMC characteristics in vitro. [Conclusion] These findings demonstrate that endothelial-lineage cells contribute to the formation of the neointimal smooth muscle cells in vascular remodeling.