Effects of substratum surface topography on the organization of cells and collagen fibers in collagen gel cultures.

This study investigated the orientation of fibroblasts and collagen cultured on microfabricated grooved or smooth titanium surfaces, as well as on tissue culture polystyrene, in the presence or absence of collagen gels. The gels were first added either to the confluent fibroblast culture on the surface (cell-gel condition) or to the fibroblasts were suspended within the collagen gel and then placed onto the surface (gel condition). Cells and collagen were observed with differential interference, polarization, and confocal laser scanning microscopy. Although the smooth surfaces had no effect on cell orientation in the gel for the first 2 weeks of culture, cells did orient with grooves regardless of the culture conditions. There was evidence for orthogonal multilayering of cells under the cell-gel condition at 4 weeks, and collagen alignment reflected cell alignment. The interaction of the collagen gel with the surface depended on whether the cell-gel or the gel condition was employed. In the former condition, the gel contracted toward the substratum, whereas the gel condition resulted in the formation of a ring of collagen loosely attached to the substratum. These results suggest that the order in which fibroblasts encounter substratum and extracellular matrix can influence the eventual matrix-cell interactions, and that substratum topography can influence matrix and cell orientation in zones not immediately in contact with the surface.