Zhao Ping, Liu Xiao, Zhang Xing, Wang Li, Su Haoran, Wang Liyi, He Ningxiang, Zhang Dongrui, Li Zhengxing, Kang Hongyan, Sun Anqiang, Chen Zengsheng, Zhou Li, Wang Min, Zhang Yinghui, Deng Xiaoyan, Fan Yubo
Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, Beijing Advanced Innovation Centre for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
Lab Chip. 2021 Jan 21;21(2):421-434. doi: 10.1039/d0lc00493f. Epub 2020 Dec 22.
Endothelial cells (ECs) in vivo are subjected to three forms of shear stress induced by luminal blood flow, transendothelial flow and interstitial flow simultaneously. It is controversial that shear stress, especially the component induced by luminal flow, was thought to inhibit the initialization of angiogenesis and trigger arteriogenesis. Here, we combined microfabrication techniques and delicate numerical simulations to reconstruct the initial physiological microenvironment of neovascularization in vitro, where ECs experience high luminal shear stress, physiological transendothelial flow and various vascular endothelial growth factor (VEGF) distributions simultaneously. With the biomimetic microfluidic model, cell alignment and endothelial sprouting assays were carried out. We found that luminal shear stress inhibits endothelial sprouting and tubule formation in a dose-dependent manner. Although a high concentration of VEGF increases EC sprouting, neither a positive nor a negative VEGF gradient additionally affects the degree of sprouting, and luminal shear stress significantly attenuates neovascularization even in the presence of VEGF. Heparinase was used to selectively degrade the heparan sulfate proteoglycan (HSPG) coating on ECs and messenger RNA profiles in ECs were analyzed. It turned out that HSPGs could act as a mechanosensor to sense the change of fluid shear stress, modulate multiple EC gene expressions, and hence affect neovascularization. In summary, distraction from the stabilized state, such as decreased luminal shear stress, increased VEGF and the destructed mechanotransduction of HSPGs would induce the initiation of neovascularization. Our study highlights the key role of the magnitude and forms of shear stress in neovascularization.
体内的内皮细胞（ECs）同时受到由管腔内血流、跨内皮血流和间质流诱导的三种剪切应力形式的作用。剪切应力，尤其是由管腔内血流诱导的成分，被认为会抑制血管生成的起始并触发动脉生成，这一点存在争议。在这里，我们结合微制造技术和精细的数值模拟，在体外重建了新生血管形成的初始生理微环境，其中内皮细胞同时经历高管腔剪切应力、生理性跨内皮血流和各种血管内皮生长因子（VEGF）分布。利用仿生微流控模型，进行了细胞排列和内皮芽生试验。我们发现管腔剪切应力以剂量依赖的方式抑制内皮芽生和小管形成。尽管高浓度的VEGF会增加内皮细胞芽生，但无论是正向还是负向的VEGF梯度都不会额外影响芽生程度，并且即使在存在VEGF的情况下，管腔剪切应力也会显著减弱新生血管形成。使用肝素酶选择性降解内皮细胞上的硫酸乙酰肝素蛋白聚糖（HSPG）涂层，并分析内皮细胞中的信使核糖核酸谱。结果表明，硫酸乙酰肝素蛋白聚糖可以作为一种机械传感器来感知流体剪切应力的变化，调节多种内皮细胞基因表达，从而影响新生血管形成。总之，从稳定状态的偏离，如管腔剪切应力降低、VEGF增加以及硫酸乙酰肝素蛋白聚糖的机械转导破坏，会诱导新生血管形成的起始。我们的研究突出了剪切应力的大小和形式在新生血管形成中的关键作用。
