In-silico rheometry of endothelial cells under start-up shear experiments

• Κύριος συγγραφέας: Ψαράκη, Κωνσταντίνα
• Άλλοι συγγραφείς: Psaraki, Konstantina
• Γλώσσα: English
• Έκδοση: 2022
• Θέματα: Poroelasticity; Fluid structure interaction; Biphasic structure interaction; Endothelium; Wall shear stress; Recirculation; Ποροελαστικότητα; Ενδοθήλιο

The endothelium, a monolayer of endothelial cells (ECs), constitutes the inner cellular lining of the blood vessels (arteries, veins, and capillaries) and the lymphatic system, and therefore is in direct contact with the blood and the circulating cells. It is now recognized to be a main pillar in the control of blood fluidity, platelet aggregation and vascular tone, a predominant factor in the regulation of immunology, inflammation and angiogenesis, a metabolizing and endocrine organ. Therefore, the response of the endothelium in variations of the hemodynamic environment is of vital importance. This implies that we should quantify fundamental dynamic quantities such as the developing shear stresses, the effect of flowing conditions on Wall Shear Stress (WSS), in addition to recirculation zones, which are indicators of atherosclerosis. Because of the (10 μ ) length of the ECs and the invasive nature of hands-on techniques when referring to the human cardiovascular system, such an approach would be difficult to be pursued experimentally. Here, we propose an in-silico rheometric emulation based on start-up and pulsating shear experiments in a representative two-dimensional domain of endothelial monolayer that accounts for the interaction of the blood plasma and the deformable ECs. Moreover, we create a three-dimensional domain representing endothelial cells and nuclei and perform compressive tests in order to investigate the poroelastic nature of the EC’s cytoplasm and retrieve its elasticity depending on the volume fraction of the cytoskeletal network. We present quantitative predictions for the shear and normal stresses on each cell for blood flow under physiological conditions and conclude that the imposition of a uniform, mean stress value above the endothelium does not correspond to true conditions. Finally, we show that wall thinning is slightly more prominent at the locus of high WSS in the range of physiological velocities, but under extreme velocities wall thinning intensely prevails at the locus of flow separation.