Novel tools for investigations of cytoskeletal re‐arrangement during alveolar epithelial‐mesenchymal transition

Abstract

Inherent in epithelial‐mesenchymal transition (EMT) is the establishment of an elongated cell morphology and formation of stress fibres. The influence of these cellular alterations on the biomechanics of lung parenchyma remains unclear. Alveolar A549 cells, after exposure to TGF‐β1, were studied using atomic force microscopy (AFM) and high content analysis (HCA) imaging.A549 cells were grown with or without TGF‐β1 in the presence or absence of a collagen I substrate for 72 h. Using AFM, the Young′s modulus of living cells was measured in contact mode. Surface membrane features were assessed on fixed cells using intermittent contact mode. In parallel, morphological and fluorescence staining intensity/distribution parameters were evaluated using a HCA imaging system.TGF‐β1 resulted in a greater than two‐fold increase in cell stiffness. This effect was augmented in the presence of collagen I. TGF‐β1‐treated cells also exhibiting a rougher surface profile with notable protrusions. In accordance with these findings, concurrent quantitative examination of the morphological attributes of stimulated cells using HCA, revealed dramatic alterations in cell shape, F‐actin content and distribution.These data indicate a strong correlation between the cytoskeletal‐associated cellular architecture and the mechanical dynamics of alveolar epithelial cells undergoing EMT.