Loading paradigms--intentional and unintentional--for cell culture mechanostimulus

Recent interest in the response of cells or tissues to mechanical stimuli has led to the introduction of a variety of laboratory devices designed to deliver quantified mechanical inputs to culture systems. Such devices commonly rely upon distention of a flexible culture substrate, achieved either by direct platen abutment or by transmural pressure differentials. Unfortunately, the substrate distentions in such systems are often unintentionally nonuniform, and typically also induce motions in the overlying liquid nutrient medium--motions which in turn exert unintended reactive stresses upon the culture layer. In order to characterize the nature of these reactive fluid stresses, computer models have been developed for the nutrient medium flow fields (ie, the velocity and pressure distributions) for three established contemporary cell culture mechanostimulus systems. Temporal and spatial distributions of reactive normal and shear stresses are reported for typical duty cycles in these respective instruments.