Cell Motility on Varying Substrate Stiffness

Endothelial cell motility has been widely studied, but most research observes single cell motion or collective cell migration on a glass substrate. Although previous findings are informative, there are few studies that observe collective cell migration on soft, physiological substrates. Here, we studied the effects of substrate stiffness on cell migration within a monolayer. To obtain substrates with different mechanical properties, polyacrylamide gels of varying stiffness were made. These gels were coated with the extracellular matrix protein fibronectin, and the surface was plated with a high density of human umbilical vein endothelial cells (HUVEC) or bovine aortic endothelial cells (BAEC). After the cells formed a complete monolayer, they were stained with Hoechst nuclear stain to visualize individual cell movement within the monolayer. We observed that the collective cell movement is slower as the substrate stiffness increases. Also, we noticed an interesting swirling motion within the monolayer, the dynamics of which were substrate-dependent. These results suggest that collective cell migration during tissue morphogenesis depends on the mechanical properties of the cellular environment, which often vary in diseased conditions.