Systematic study of osteoblast and fibroblast response to roughness by means of surface-morphology gradients

The surface roughness of a medical implant is of great importance since the surface is in direct contact with the host tissue (e.g. bone, fibrous tissue). The response of cells to roughness is different depending on the cell type. However, the influence of roughness on cell behavior has only rarely been systematically studied. We have developed a surface-modification process to produce roughness gradients that cover a wide range of roughness values on one substratum. Such gradients allow for systematic investigations of roughness on cell behavior. Gradients were fabricated using a two-step roughening and smoothening process, involving sandblasting and a subsequent chemical polishing step. In order to produce a set of identical surfaces we applied a replica technique. Cell experiments were carried out with rat calvarial osteoblasts (RCO) and human gingival fibroblasts (HGF). RCOs showed a significantly increased proliferation rate with increasing surface roughness. The footprint of osteoblasts varied in size at different positions on the gradient, remaining small on the rough end of the gradient and increasing considerably as the roughness decreased. HGF showed the opposite proliferation behavior, proliferation decreasing with increasing roughness. The fibroblast morphology was found to be similar to that seen for osteoblasts.