Effects of substrate stiffness on cell morphology, cytoskeletal structure, and adhesion

Abstract

The morphology and cytoskeletal structure of fibroblasts, endothelial cells, and neutrophils are documented for cells cultured on surfaces with stiffness ranging from 2 to 55,000 Pa that have been laminated with fibronectin or collagen as adhesive ligand. When grown in sparse culture with no cell-cell contacts, fibroblasts and endothelial cells show an abrupt change in spread area that occurs at a stiffness range around 3,000 Pa. No actin stress fibers are seen in fibroblasts on soft surfaces, and the appearance of stress fibers is abrupt and complete at a stiffness range coincident with that at which they spread. Upregulation of alpha5 integrin also occurs in the same stiffness range, but exogenous expression of alpha5 integrin is not sufficient to cause cell spreading on soft surfaces. Neutrophils, in contrast, show no dependence of either resting shape or ability to spread after activation when cultured on surfaces as soft as 2 Pa compared to glass. The shape and cytoskeletal differences evident in single cells on soft compared to hard substrates are eliminated when fibroblasts or endothelial cells make cell-cell contact. These results support the hypothesis that mechanical factors impact different cell types in fundamentally different ways, and can trigger specific changes similar to those stimulated by soluble ligands.

Polyelectrolyte Multilayer Films of Controlled Stiffness Modulate Myoblast Cell Differentiation

“…Matrix stiffness was first found to have an effect on cell morphology, adhesion, proliferation and migration [6,8,9,10,11] . Very different cell types have been shown to be sensitive to matrix stiffness [6,12,13,14] although the particular responses appear to be cell-type specific [9] . Most of these studies deal with "model" 3D gels of polyacrylamide (PA) or polydimethylsiloxane (PDMS), which can be prepared easily and whose elasticity can be tuned by varying the cross-linker concentration [6,14] .…”

Assay to mechanically tune and optically probe fibrillar fibronectin conformations from fully relaxed to breakage

“…Differences in substrate rigidity (Engler et al, 2006;Galbraith et al, 2002;Giannone and Sheetz, 2006;Kostic and Sheetz, 2006;Yeung et al, 2005) as well as micro-and nanoscale features (Dalby et al, 2005) have been correlated with profound effects on cell adhesion, morphology, proliferation, and gene regulation. The rigidity of a substrate, for example, determines whether or not mammary epithelial cells up-regulate integrin expression and differentiate into a malignant phenotype (Paszek et al, 2005), and also dictates whether mesenchymal stem cells differentiate into bone, muscle, or neuronic tissue (Engler et al, 2006).…”

Contribution of Bone Tissue Modulus to Breast Cancer Metastasis to Bone

“…Thus cells cultured on rigid substrates show upregulated integrin expression [76], more stress fibers [76], stable focal adhesions [59,71], and greater traction forces [51]. Conversely, cells cultured on compliant substrates show dynamic adhesions [59] and are not as spread [76].…”