Stretch during mechanical ventilation induces stress on alveolar epithelial cells (AEC). Experimental mechanostimulation of AEC mimics this stress and helps to understand fundamental processes in consequence of stretch.
In this experiment we investigated whether mechanical stretch exerts different impact on form stability of alveolar carcinoma cells (CC) and of non-tumorous alveolar epithelial cells type 2 (AEC-II).
As CC the human alveolar carcinoma cell line A549 was employed. Non-tumorous AEC-II were isolated from tumor-free resected lung tissue. Cell isolation via slicing, dispase digestion, nylon filtration, Ficoll density centrifugation, adherence separation and CD45- selection results in purity of 90–94% of AEC-II.
2×106 CC / 7×106 AEC-II adhered within 3.5 / 15 h on a 3.8 cm2 latex membrane. After cell adherence the membrane was fixed into an experimental mechanostimulator, which deflected the membrane by insufflation of air to a surface increase in membrane area of 1 / 6 / 13 or 21%.
Cell form was analyzed by light microscopy.
An increase of the surface area up to 13% induces no change of the ball-shaped form of AEC-II, at 21% the cells divulsed. CC deformed star-shaped. They stayed attached to the membrane up to an area increase of more than 100%. In contrast to AEC-II, CC are able to compensate static biaxial stretch by changing their conformation.
Our study demonstrates that human alveolar carcinoma cells are more resistant to static biaxial stretch than non-tumorous alveolar epithelial cells type 2.