Surface topography induces fibroblast adhesion on intrinsically nonadhesive poly(ethylene glycol) substrates

Important in developing new biomaterials is the prevention of unspecific protein adsorption and cell interactions that in vivo can lead to a foreign body reaction. On the other hand, the material should support the growth of a specific cell type in a defined way. We investigate the possibility of manipulating cellular behavior on an intrinsically nonadhesive material by topographic patterning without additional surface chemistry modifications. The biomaterial applied is a hydrogel cross-linked from star-shaped poly(ethylene glycol) macromonomers (starPEG). Cell biological studies with a mouse fibroblast cell line (L929) showed that, while substrates with a smooth surface are nonadhesive, as expected, imprinted topography enabled cell adhesion and spreading. The fibroblasts aligned to micrometer groove patterns and were, depending on the respective dimensions, able to span or enter the grooves. Especially substrates with topography dimensions in the cell size range or smaller (<10 microm) lead to an establishment of stable cell-surface contacts (vinculin and actin accumulation). On micrometer post patterns the cells spread on top of the pillars and wrapped around the structures. The strong influence of the topography shows that nonadhesive materials do not necessarily have to be specifically biofunctionalized to enable cell adhesion. Possible explanations for the peculiar cell behavior are discussed in terms of (initial) protein adsorption and geometry-dependent cytoskeletal arrangements.