IMPROVED IN-VITRO RHEOLOGICAL SYSTEM FOR STUDYING THE EFFECT OF FLUIDSHEAR-STRESS ON CULTURED-CELLS

A rheological in vitro system has been developed to study and quantify cellular adhesion under precisely defined external shear forces. The system is similar to a cone-and-plate viscosimeter. A rotating transpa rent cone produces both steady and pulsatile flow profiles on cultured cells. Direct visualization of cells by phase-contrast or fluorescenc e optics and connection of the optical system to a computer-controlled x/y-linear stage allows automatic recording of any point of the cell cultures. With the use of up to 12 individual rheological units, this setup allows the quantitative analysis of cell substrate adhesion by d etermination of cell detachment kinetics. Two examples of application of this rheological system have been studied. First, we show that the extracellular matrix protein laminin strongly increases endothelial ce ll adhesion under fluid shear stress. In a second approach, we obtaine d further support for the concept that shear stress-induced formation of actin filament stress fibers is important for endothelial cells to resist the fluid shear stress; inhibition of stress fiber formation by doxorubicin resulted in significant detachment of endothelial cells e xposed to medium levels of fluid shear stress (5 dyn/cm2). No detachme nt was seen under resting conditions.