Shear stress effects on human embryonic kidney cells in Vitro

Human embryonic kidney cells grown as an attached, confluent monolayer on a flat substrate were subjected to steady, uniform laminar flow of medium in a specially designed chamber in which flow patterns and shear stress are accurately defined and controlled. Experiments were performed for shear stress levels ranging from 0.2 to 6.0 N/m(2) with times of exposure to the shear stress ranging from 2 to 24 h. The influence of the shear field was slight at low shear stress (0.26 N/m(2)). Higher stress levels (0.65 N/m(2) and higher) had significant effects on cell morphology, and on the post-shear release of urokinase enzyme. Still higher stress levels (2.6 N/m(2) and higher) caused marked reduction in cell viability. These results may be of interest in addressing practical problems in developing commercial biosynthesis reactors.