The Dynamic Response of Vascular Endothelial Cells to Fluid Shear Stress

TLDR

Modulation of endothelial behavior by fluid shear stresses may be relevant to normal vessel wall physiology and the pathogenesis of vascular diseases such as atherosclerosis. The study develops an in‑vitro system to examine how vascular endothelial cells dynamically respond to controlled fluid shear stress. The system uses cultured bovine aortic endothelial monolayers in a cone‑plate apparatus that generates uniform fluid shear stress across replicate samples. Under 1–5 dynes/cm², subconfluent cultures proliferate similarly to static controls and reach comparable saturation density; at 5–10 dynes/cm², confluent monolayers change shape, align with flow, and wound regeneration depends on force direction, while shear stress also influences endocytosis, cytoskeletal assembly, and nonthrombogenic surface properties, indicating that mechanical forces directly affect endothelial structure and function.

Abstract

We have developed an in-vitro system for studying the dynamic response of vascular endothelial cells to controlled levels of fluid shear stress. Cultured monolayers of bovine aortic endothelial cells are placed in a cone-plate apparatus that produces a uniform fluid shear stress on replicate samples. Subconfluent endothelial cultures continuously exposed to 1–5 dynes/cm2 shear proliferate at a rate comparable to that of static cultures and reach the same saturation density (≃ 1.0–1.5 × 105 cells/cm2). When exposed to a laminar shear stress of 5–10 dynes/cm2, confluent monolayers undergo a time-dependent change in cell shape from polygonal to ellipsoidal and become uniformly oriented with flow. Regeneration of linear “wounds” in confluent monolayer appears to be influenced by the direction of the applied force. Preliminary studies indicate that certain endothelial cell functions, including fluid endocytosis, cytoskeletal assembly and nonthrombogenic surface properties, also are sensitive to shear stress. These observations suggest that fluid mechanical forces can directly influence endothelial cell structure and function. Modulation of endothelial behavior by fluid shear stresses may be relevant to normal vessel wall physiology, as well as the pathogenesis of vascular diseases, such as atherosclerosis.