Geometric preferences of lamellipodia extension

Cell motility is accomplished by the extension of processes called lamellipodia, which are driven by local actin polymerization. Work to date has focused on the role of soluble factors and insoluble extracellular matrix (ECM) in modulating directional cell migration. We conducted studies using micropatterned substrates to elucidate how ECM regulates the direction of lamellipodial extension. When single fibroblast cells were cultured on individual cell-sized square adhesive islands coated with ECM, they extend to the edge of the island and assume a square shape. When these square cells were stimulated with platelet-derived growth factor (PDGF), they preferentially extended lamellipodia from the corners versus the sides. This preference implies that ECM geometry and higher order cell architecture governs chemical pathways that drive the extension of lamellipodia.