ATII cells respond to mechanical strain with release of lamellar bodies and eventually with a rupture of the cell membrane. We applied different degrees of equibiaxial strain to AT II cells and investigated structural alterations of the cell membrane and the cytoskelton.

Cells were cultivated on elastic silicone membranes (SM) and strained using the Cell Stretcher 2.0 (AdvancedLab, Austria). Analysis of membrane profiles showed a steady flattening out of the apical cell membrane by increasing the strain whereas the basal cell membrane had already flattened out entirely at only 110% of the initial SM area (SMA). At 135% SMA the cell membrane ruptured although a normal overall ultrastructure. Fluorescence labeling of the cytoskeleton revealed that cell strain is reflected by a staightening out of individual bundles of cytokeratin. The distance between the two dense plaques of the desmosomes - the insertion points of the CK in the membrane - showed a significant increase of this parameter at 110% SMA, whereas higher strain lead to an unexpected decrease.

Our results indicate multiple morphological changes in response to cell stretch, possibly with physiological and pathophysiological consequences. Supported by FWF grants P15472, P15743, DFG grant D1402, EU ("Pulmo-Net".