Cell type-specific modulation of fibronectin adhesion functions on chemically-derivatized self-assembled monolayers.

Cell type-specific responses (microfilament stress fibers for fibroblasts or neurites for neuroblastoma cells) were evaluated in culture on inert and chemically-derivatized silane substrata adsorbed with fibronectin (Fn). Substrata of self-assembled monolayers contain a 14-17 carbon aliphatic chain terminating with different chemical endgroups -- [CH3], [C=C], [Br], [CN], [Diol], [COOH], [NH2], [SH], [SCOCH3], or [SO3H]. Fn adsorbed effectively to all derivatized surfaces. 3T3 fibroblasts or neuroblastoma cells attached equivalently to all surfaces preadsorbed with Fn, indicating availability of receptor binding sites on Fns. However, transmembrane signaling from Fn(adsorbed): receptor(cell) surface complexes yielded a range of abilities for generating F-actin stress fibers in fibroblasts or neurites in neuroblastoma cells. Efficiency for stress fiber formation was very different from that of neurite extension. The same chemical endgroups on glass, titanium, or germanium yielded the same patterns of cellular physiological responses, indicating that inert substrata do not act at a distance and that only chemical endgroups regulate Fn signaling functions. When adhesion-inert albumin is co-adsorbed with Fn, efficiency of neurite extension is improved on some surfaces or diminished on others. These results indicate that the conformation of Fn(adsorbed) changes in specific ways on derivatized substrata. Change in Fn conformation was confirmed by FTIR/ATR spectroscopy experiments of Fn(adsorbed). Overall, these studies indicate changes in Fn conformations on chemically-derivatized self-assembled monolayers leading to up- or down-regulation of cell type-specific physiological responses from receptors via their signaling pathways. They also offer predictability for regulating responses of specific cell types when these cells interact with biomaterial implants in vivo.