Mechanical load and mechanical integrity of lung cells - experimental mechanostimulation of epithelial cell- and fibroblast-monolayers.

Experimental mechanostimulation of soft biologic tissue is widely used to investigate cellular responses to mechanical stress or strain. Reactions on mechanostimulation are investigated in terms of morphological changes, inflammatory responses and apoptosis/necrosis induction on a cellular level. In this context, the analysis of the mechanical characteristics of cell-layers might allow to indicate patho-physiological changes in the cell-cell contacts. Recently, we described a device for experimental mechanostimulation that allows simultaneous measurement of the mechanical characteristics of cell-monolayers. Here, we investigated how cultivated lung epithelial cell- and fibroblast-monolayers behave mechanically under different amplitudes of biaxial distension. The cell monolayers were sinusoidally deflected to 5%, 10% or 20% surface gain and their mechanical properties during mechanostimulation were analyzed. With increasing stimulation amplitudes more pronounced reductions of cell junctions were observed. These findings were accompanied by a substantial loss of monolayer rigidity. Pulmonary fibroblast monolayers were initially stiffer but were stronger effected by the mechanostimulation compared to epithelial cell-monolayers. We conclude that, according to their biomechanical function within the pulmonary tissue, epithelial cells and fibroblasts differ with respect to their mechanical characteristics and tolerance of mechanical load.