Matrix stiffness regulates migration of human lung fibroblasts

Abstract

In patients with pulmonary diseases such as idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome, progressive pulmonary fibrosis is caused by dysregulated wound healing via activation of fibroblasts after lung inflammation or severe damage. Migration of fibroblasts toward the fibrotic lesions plays an important role in pulmonary fibrosis. Fibrotic tissue in the lung is much stiffer than normal lung tissue. Emerging evidence supports the hypothesis that the stiffness of the matrix is not only a consequence of fibrosis, but also can induce fibroblast activation. Nevertheless, the effects of substrate rigidity on migration of lung fibroblasts have not been fully elucidated. We evaluated the effects of substrate stiffness on the morphology, α‐smooth muscle actin (α‐SMA) expression, and cell migration of primary human lung fibroblasts by using polyacrylamide hydrogels with stiffnesses ranging from 1 to 50 kPa. Cell motility was assessed by platelet‐derived growth factor (PDGF)‐induced chemotaxis and random walk migration assays. As the stiffness of substrates increased, fibroblasts became spindle‐shaped and spread. Expression of α‐SMA proteins was higher on the stiffer substrates (25 kPa gel and plastic dishes) than on the soft 2 kPa gel. Both PDGF‐induced chemotaxis and random walk migration of fibroblasts precultured on stiff substrates (25 kPa gel and plastic dishes) were significantly higher than those of cells precultured on 2 kPa gel. Transfection of the fibroblasts with short interfering RNA for α‐SMA inhibited cell migration. These findings suggest that fibroblast activation induced by a stiff matrix is involved in mechanisms of the pathophysiology of pulmonary fibrosis.

Cell Shape and Durotaxis Follow from Mechanical Cell-Substrate Reciprocity and Focal Adhesion Dynamics: A Unifying Mathematical Model

“…Thus, the cell area has increased more than 2.5 fold on the stiffest substrate compared to the softest substrates. This factor is consistent with experimental observations [1,45,46]. We also investigated if the model could qualitatively predict spreading dynamics.…”

Recapitulating in vivo-like plasticity of glioma cell invasion along blood vessels and in astrocyte-rich stroma

“…Glioma invasion modes observed in hyaluronan-rBM vs rBM-plastic interfaces may result from the different molecular and mechanical characteristics of the interface along which they migrated, including coverage of rBM proteins by hyaluronan which may provide confinement and further modulate ligand availability for cell adhesion systems and the stiffness of migration substrate. These parameters may cooperatively influence the retention of cell–cell junctions, migration mode and speed (Haeger et al 2014 ; Canver et al 2016 ; Asano et al 2017 ; Bangasser et al 2017 ). Accordingly, both glioma cell lines moving collectively under rBM established linear or focal adherens junctions at cell–cell contacts which were positive for N-cadherin and β-catenin, whereas glioma cells migrating on a 2D surface lacked junctional β-catenin and showed its redistribution to the cytoplasm (Fig.…”

Feeling Things Out: Bidirectional Signaling of the Cell–ECM Interface, Implications in the Mechanobiology of Cell Spreading, Migration, Proliferation, and Differentiation

“…Durotaxis is also an important feature in the progression of diseases with fibrotic signatures. During pulmonary fibrogenesis, formation of stiff foci in lung tissues initiates fibroblast migration toward the lesion, leading to expression of α‐smooth muscle actin, a marker of myofibroblast activity and a pro‐matrix secretory phenotype 176…”