Equibiaxial deformationinduced injury of alveolar epithelial cells in vitro

The onset of ventilator-induced lung injury (VILI) is linked to a num-ber of possible mechanisms. To isolate the possible role of alveolar epithelial deformation in the development of VILI, we have devel-oped an in vitro system in which changes in alveolar epithelial cell viability can be measured after exposure to tightly controlled and physiologically relevant deformations. We report here a study of the relative effect of deformation frequency, duration, and amplitude on cell viability. We exposed rat primary alveolar epithelial cells to a vari-ety of biaxial stretch protocols, and assessed deformation-induced cell injury quantitatively, using a fluorescent cell viability assay. Defor-mation-induced injury was found to depend on repetitive stretching, with cyclic deformations significantly more damaging than tonically held deformations. In cyclically deformed cells, injury occurred rap