Mechanosensing of Cells in Laminin-Fuctionalized Biomembrane-Mimicking Substrates

Abstract

Adherent cells actively probe and respond to the mechanical properties of their environment. Studies of cellular mechanosensing are mostly conducted on polymeric substrates of adjustable elasticity with immobilized cell-substrate linkers that neglect the dynamic and viscoelastic nature of tissues. Here, we study cell migration on a polymer-tethered multi-lipid bilayer substrate with mobile linkers and dissipative material properties. The substrates are functionalized with laminin, which replicates the linkages of cells to the extracellular matrix. The polymer-tethered lipids connecting the bilayer stacks do not hinder the lateral mobility of individual cell linker molecules in the fluid lipid bilayer matrix, but obstruct or even prevent the free lateral diffusion of clusters of cell linkers. These biomembrane-mimicking substrates therefore exhibit a viscous response with respect to individual linkers, and an elasto-plastic response in the presence of linker clusters, allowing the cells to rearrange and recruit ligands. Moreover, the mechanical properties of the substrate can be tuned by stacking multiple bilayers. Experiments with mouse embryonic fibroblasts confirm that cells can sense linker mobility and dissipative mechanical properties of the substrate. Cells respond to decreasing linker mobility, decreasing substrate elasticity, and increasing substrate plasticity with a reduction in spreading area, cell stiffness, traction magnitude, and focal adhesion size, but with an increase in focal adhesion number density. In conclusion, the results illustrate that cells change their morphological and mechanical properties in response to changes in substrate elasto-plasticity and linker mobility.