Fibroblast response to microtextured silicone surfaces: texture orientation into or out of the surface

Previous studies suggested that surface topographic configurations of 1-3 microns influence cellular behavior and tissue response. They did not address which specific aspect of the configurations elicits the cellular response. We therefore investigated the effect of the orientation of several surface configurations. Seven different textures on polydimethyl siloxane (silicone; Dow Corning Silastic) specimens were used to test the question of whether orientation into (down) or out of the surface (up) affected cellular response to a material. The textures were smooth and photoetched configurations of 2 microns up, 2 microns down, 5 microns up, 5 microns down, 10 microns up, and 10 microns down. The response of cultured fibroblasts on these surfaces was compared with that of a standard tissue culture material, polyethylene terepthalate (Thermanox). The cell density was measured over a 12-day period with the use of a colorimetric assay. The uptake of methylene blue was measured daily and compared as an absorbance in a destaining agent. Cells on the 2 and 5 microns up arrays showed increased rates of proliferation and cell density as compared with their down counterparts. This would indicate that textures of 2 and 5 microns have a significant influence on cell growth, and that the surface with hills has a greater effect than the surface with wells. In contrast, the 10 microns up and 10 microns down arrays did not prove to be statistically different from smooth ones. This indicates that the orientation effect is related to the configuration size and that this configuration size is not viewed differently from smooth silicone by the cells. The presented data are in agreement with results of this laboratory and others that fibroblasts recognize the dimensions of surface configurations and react accordingly. Specifically, they appear to react to the uppermost surface area presented to them, but conclusive data can only be obtained from a study of the focal adhesions.