Regulation of Cell Motility on Polymer Substrates via

In vivo, motile epidermal tissues frequently encounter ligand microinterfaces that are dy-namic, owing to rapid cell-mediated substrate phagocytosis. In this study, we have exam-ined cell motility phenomena in response to the adhesion ligand, collagen, which was pre-sented on cell-internalizable 400-nm colloidal gold microcarriers. Normal human keratinocytes were seeded onto collagen-adsorbed poly(lactide-co-glycolide) (PLGA) films that were predeposited with varying densities of the ligand-associated microcarriers (LAMs), such that the overall ligand density and the ligand loading per microcarrier were invariant. Cells seeded on LAMs exhibited rapid and distinct cytoskeletal redistribution resulting in numerous filopodial extensions, indicative of activation of cell motility processes. We report that the population-averaged cell migration rate of cells, m, was increased from 2 mm2/min on collagen substrates lacking the microcarriers, to,50 mm2/min on collagen presenting LAMs. An increase in LAM density to 1.2 LAMs per mm2 was found to maximize m, as well as the directional persistence and speed of cell migration, whereas very high LAM densities saturated cell internalization and diminished migration rates. The cell–LAM interactions es