Oscillatory shear stress and hydrostatic pressure modulate cell-matrix attachment proteins in cultured endothelial cells |
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Authors: | Olivier Thoumine Robert M Nerem Feggy R Girard |
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Institution: | (1) Bioengineering Center and School of Mechanical Engineering, Georgia Institute of Technology, 30332-0230 Atlanta, Georgia;(2) School of Biology, Georgia Institute of Technology, 30332-0230 Atlanta, Georgia |
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Abstract: | Summary Endothelial cells (ECs) may behave as hemodynamic sensors, translating mechanical information from the blood flow into biochemical
signals, which may then be transmitted to underlying smooth muscle cells. The extracellular matrix (ECM), which provides adherence
and integrity for the endothelium, may serve an important signaling function in vascular diseases such as atherogenesis, which
has been shown to be promoted by low and oscillating shear stresses. In this study, confluent bovine aortic ECs (BAECs) were
exposed to an oscillatory shear stress or to a hydrostatic pressure of 40 mmHg for time periods of 12 to 48 h. Parallel control
cultures were maintained in static condition. Although ECs exposed to hydrostatic pressure or to oscillatory flow had a polygonal
morphology similar to that of control cultures, these cells possessed more numerous central stress fibers and exhibited a
partial loss of peripheral bands of actin, in comparison to static cells. In EC cultures exposed to oscillatory flow or hydrostatic
pressure, extracellular fibronectin (Fn) fibrils were more numerous than in static cultures. Concomitantly, a dramatic clustering
ofα
5β1 Fn receptors and of the focal contact-associated proteins vinculin and talin occurred. Laminin (Ln) and collagen type IV
formed a network of thin fibrils in static cultures, which condensed into thicker fibers when BAECs were exposed to oscillatory
shear stress or hydrostatic pressure. The ECM-associated levels of Fn and Ln were found to be from 1.5-to 5-fold greater in
cultures exposed to oscillatory shear stress or pressure for 12 and 48 h, than in static cultures. The changes in the organization
and composition of ECM and focal contacts reported here suggest that ECs exposed to oscillatory shear stress or hydrostatic
pressure may have different functional characteristics from cells in static culture, even though ECs in either environment
exhibit a similar morphology. |
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Keywords: | endothelial cell hydrostatic pressure oscillatory flow extracellular matrix focal contact |
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