具有梯度的流体切应力促进血管内皮细胞增殖

目的探讨流体切应力(shear stress,SS)对血管内支架边缘内皮细胞(endothelial cells,ECs)增殖的影响。方法应用具有切应力梯度的平行平板流动腔(梯度切应力组)和普通矩形平行平板流动腔(恒定切应力组),分别对ECs施加0.566￣1.438Pa和1.137Pa的切应力,加载时间6h,以未施加切应力的ECs为静止对照组。流式细胞仪检测各组ECs细胞周期的变化。结果梯度切应力组ECs在受力6h后进入S期与G2+M期细胞明显多于静止对照组与稳定切应力组(P<0.05);恒定切应力组的ECs受力后进入S期与G2+M期细胞明显少于其他两组(P<0.05)。结论梯度切应力促进ECs进入分裂增殖期,而稳定的层流切应力则产生对ECs细胞周期的抑制作用。提示血管内支架植入后,继发的血流切应力改变诱导细胞进入分裂、增殖期,这可能是引起支架内再狭窄过程中血管内膜增生的原因之一。

Gradient shear stress induces vascular endothelial cells proliferation

Objective To explore the effect of shear stress on proliferation of vascular endothelial cells (ECs) around stent edge. Methods ECs were divided into static group (as control group), gradient shear stress group (ECs in parallel-plate flow chamber (PPFC) with gradient shear stress ) and steady shear stress group (ECs in rectangular PPFC). Two shear stress groups were subjected to 0.566-1.438 Pa and 1.137 Pa for 6h, respectively. The ECs cell cycle in each group was detected by flow cytometry (FCM). Results The amount of ECs entering cell cycle phases of S and G2+M in gradient shear stress group was much more than that in static group and steady shear stress group P( < 0.05), while the amount of ECs in steady shear stress group entering phases of S and 2G+M was significantly less than that in other two groups (P < 0.05).Conclusion Gradient shear stress induces ECs to enter phases of proliferation while the cell cycle phase is inhibited by the steady laminar shear stress. The result suggests that the gradient shear stress caused by planted stent can induce ECs proliferation, which may play an important role in initial hyperplasia in the restenosis process within the stent.