J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA.
Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611, USA.
Microvasc Res. 2022 Jul;142:104360. doi: 10.1016/j.mvr.2022.104360. Epub 2022 Mar 15.
Shear stress is recognized as a regulator of angiogenesis. However, the shear stress experienced by the endothelial cells of capillary sprouts remains unknown. The objective of this study was to estimate shear stress due to local interstitial flow along endothelial tip cells at the end of the capillary sprout lumen. Computational fluid dynamics were used to model flow within a blind-ended vessel, transendothelial flow across the vessel wall, and flow within the surrounding perivascular/interstitial space. Shear stress along the wall of the tip cells was calculated while varying sprout length, perivascular space channel width, and vessel wall hydraulic conductivity. Increasing sprout length, increasing wall hydraulic conductivity, and decreasing perivascular space width increased shear stress magnitude. Wall shear stress magnitude within the lumen ranged from 0.015 to 0.55 dyne/cm at the sprout entrance and linearly decreased to near zero at the base of the tip cells. Tip cell wall shear stress magnitude due to interstitial flow ranged from 0.009 to 4.65 dyne/cm. In 3 out of 8 cases, shear stress magnitude was above 1 dyne/cm and considered physiologically relevant. The results provide a framework for discussing the role of local mechanical cues in regulating endothelial cell dynamics involved in angiogenesis. Mainly, interstitial flows may generate physiologically relevant shear stresses on tip cells in certain scenarios. This source of tip cell shear stress has not been previously considered or modeled.
切应力被认为是血管生成的调节因子。然而，毛细血管芽内皮细胞所经历的切应力尚不清楚。本研究旨在估计沿毛细血管芽腔末端内皮尖端细胞的局部间质流引起的切应力。通过计算流体动力学来模拟盲端血管内的流动、跨血管壁的内皮细胞间流动以及周围血管周围/间质空间内的流动。在改变芽长度、血管周围空间通道宽度和血管壁水力传导率的情况下，计算尖端细胞壁上的切应力。增加芽长度、增加壁水力传导率和减小血管周围空间宽度会增加切应力大小。在芽入口处，管腔内的壁切应力大小范围为 0.015 至 0.55 达因/厘米，并在线性降低到尖端细胞底部附近的接近零。由于间质流引起的尖端细胞壁切应力大小范围为 0.009 至 4.65 达因/厘米。在 8 个案例中有 3 个，切应力大小超过 1 达因/厘米，被认为具有生理相关性。该结果为讨论局部机械线索在调节血管生成中涉及的内皮细胞动力学的作用提供了一个框架。主要是，间质流在某些情况下可能会在尖端细胞上产生具有生理相关性的切应力。这种尖端细胞切应力源以前没有被考虑或建模过。
