Influence of pulsatile flow on the behaviour of human fibroblasts adhered to glass

In the human body, cells contacting biomaterials surfaces are frequently exposed to pulsatile shear stresses, e.g. blood vessel prostheses. Most studies involving shear, however, try to achieve a steady, pulse-free shear stress in studying cell-biomaterial interactions. In this study, human fibroblasts adhering to glass were exposed to an applied 0.5 Hz square-wave pulsatile shear, created in a parallel plate flow chamber by a computer-driven pump. Cells were also exposed to the single lower and higher shear stresses making up the square wave in the presence or absence of pressure variations due to the peristaltic roller pump. Results indicate that cells exposed to the applied square-wave regime showed a detachment rate in between that of the single shear stresses making up the square wave. Furthermore, the presence of the pulsations gave rise to elongated cell shapes in the direction of flow and the formation of a more extensive filopodial network than in the absence of pulsations. This was also true for cells exposed to the high shear component in the presence of pressure variations. Cells exposed to the high shear component without any pressure variations, however, adapted spherical shapes after the onset of flow.