Department of Bioengineering, Imperial College London, London SW7 2AZ, UK.
Department of Aeronautics, Imperial College London, London SW7 2AZ, UK.
J R Soc Interface. 2021 Jan;18(174):20200772. doi: 10.1098/rsif.2020.0772. Epub 2021 Jan 13.
The alignment of arterial endothelial cells (ECs) with the mean wall shear stress (WSS) vector is the prototypical example of their responsiveness to flow. However, evidence for this behaviour rests on experiments where many WSS metrics had the same orientation or where they were incompletely characterized. In the present study, we tested the phenomenon more rigorously. Aortic ECs were cultured in cylindrical wells on the platform of an orbital shaker. In this system, orientation would differ depending on the WSS metric to which the cells aligned. Variation in flow features and hence in possible orientations was further enhanced by altering the viscosity of the medium. Orientation of endothelial nuclei was compared with WSS characteristics obtained by computational fluid dynamics. At low mean WSS magnitudes, ECs aligned with the modal WSS vector, while at high mean WSS magnitudes they aligned so as to minimize the shear acting across their long axis (transverse WSS). Their failure to align with the mean WSS vector implies that other aspects of endothelial behaviour attributed to this metric require re-examination. The evolution of a mechanism for minimizing transverse WSS is consistent with it having detrimental effects on the cells and with its putative role in atherogenesis.
动脉内皮细胞（ECs）与平均壁切应力（WSS）矢量对齐是其对流动响应的典型范例。然而，这种行为的证据基于许多 WSS 指标具有相同方向或其特征描述不完整的实验。在本研究中，我们更严格地测试了这一现象。将主动脉 ECs 培养在轨道摇床平台上的圆柱形井中。在这个系统中，细胞的取向会因它们对齐的 WSS 指标而有所不同。通过改变介质的粘度，可以进一步增强流动特征的变化，从而改变可能的取向。将内皮细胞核的取向与通过计算流体动力学获得的 WSS 特征进行比较。在低平均 WSS 幅度下，ECs 与模态 WSS 矢量对齐，而在高平均 WSS 幅度下，它们沿其长轴（横向 WSS）对齐以最小化剪切作用。它们未能与平均 WSS 矢量对齐意味着归因于该指标的其他内皮行为方面需要重新检查。用于最小化横向 WSS 的机制的演变与其对细胞的有害影响以及其在动脉粥样硬化形成中的潜在作用是一致的。
