Response of single, pairs, and clusters of epithelial cells to substratum topography

Cells cultured on grooved substrata change their shape, orientation, and direction of locomotion in response to substratum topography, a phenomenon called contact or topographic guidance. Porcine epithelial cells (E-cells) spread on micromachined grooved or smooth control surfaces were examined by epifluorescence and confocal microscopy to determine area, cell shape, and orientation in conjunction with distributions and orientations of actin filaments and microtubules. Single cells, cells within a pair or cluster, and pairs or clusters considered as a unit were compared. As expected, cell contact increased cell spreading, but surprisingly, increased cell contact influenced cell shape on smooth and grooved surfaces and increased alignment of cells spread on grooves. Both actin filaments and microtubules aligned initially and most consistently along the walls and ridge-groove edges. Single E-cells displayed the least variability of aligned cytoskeletal patterns. E-cells within clusters displayed the most variability as local topographic effects on the cytoskeleton could be overridden by adjacent cell contact. Overall, contact guidance of E-cells was neither synonymous with nor contingent upon an elliptical morphology oriented to the topography. E-cells also differed from fibroblasts in their response to cell contact and in their lack of a relationship between cell polarity and locomotion.