Dynamic Cellular Interactions with Extracellular Matrix Triggered by Biomechanical Tuning of Low-Rigidity, Supported Lipid Membranes

The behavior of cells in a tissue is regulated by chemical as well as physical signals arising from their microenvironment. While gel-based substrates have been widely used for mimicking a range of substrate rigidities, there is a need for the development of low rigidity substrates for mimicking the physical properties of soft tissues. In this study, the authors report the development of a supported lipid bilayer (SLB)-based low rigidity substrate for cell adhesion studies. SLBs are functionalized with either collagen I or fibronectin via covalent, amine coupling to a carboxyl group-modified lipid molecule. While the lipid molecules in the bilayer show long-range lateral mobility, the covalently functionalized extracellular matrix (ECM) proteins are immobile on the bilayer surface. Specific adhesion of cells results in an enrichment of the protein on the bilayer and the appearance of a zone of depletion around the cells. Further, the lateral reorganization of the ECM proteins is controlled by altering the fluidity of lipid molecules in the substrate. Thus, the experimental platform developed in this study can be utilized for addressing basic questions related to cell adhesion on low rigidity substrates as well as biomedical applications requiring adhesion of cells to low rigidity substrates.