POLYMER SURFACE-CHEMISTRY AND BONE CELL-MIGRATION

Implant devices for orthopaedic applications may be improved if the su rface of the biomaterial provides for osteointegration. To understand the effect of hydrophilicity on colonisation by human bone derived (HB D) cells, we compared untreated polystyrene (PS) and a sulfuric acid-t reated PS surface for mechanisms of cell migration. The chemical compo sition of the acid-treated PS surface was analysed by monochromatic X- ray photoelectron spectroscopy;nd found to contain various oxidatively produced groups and a minor amount of sulfonate groups. It was found that migration of HBD cells on both PS and acid-treated PS surfaces wa s dependent on the presence of vitronectin (Vn) and was higher on the hydrophilic acid-treated surface. Minimal migration of HBD cells occur red on either surface in the absence of Vn, even when fibronectin was present in the culture medium. Using radiolabelled protein, it was sho wn that Vn adsorption onto the acid-treated surface was two to three f old greater than that on the hydrophobic PS. When HBD cells were seede d onto a patterned surface in a medium containing Vn, the cells prefer entially colonised the hydrophilic region and few, if any, cells trave rsed the haptotactic boundary from the hydrophilic to the hydrophobic side. Thus the enhanced HBD cell migration seen on the acid-treated PS compared viith the untreated PS surface and the haptotactic boundary phenomenon, relate to Vn adsorption.