Multiple attachment mechanisms of corneal epithelial cells to a polymer--cells can attach in the absence of exogenous adhesion proteins through a mechanism that requires microtubules.

The initial adhesion of epithelial cells is recognized as a critical determinant in the epithelialization of a polymer. Previously, the attachment of a variety of cell types to a polymer has been shown to be mediated by fibronectin and/or vitronectin that adsorb onto the polymer surface from the serum used to supplement the culture medium. Such an attachment reaction, dependent upon exogenous cell-adhesive proteins, is likely to involve the actin cytoskeleton and integrin receptors on the cell surface. In the current study, we have examined the attachment of recently isolated corneal epithelial cells to tissue culture polystyrene in the absence of such exogenous cell-adhesive proteins. Under these circumstances, there is an alternative mechanism of attachment operative between corneal epithelial cells and the polymer surface which is essentially independent of the adsorption of serum-derived fibronectin and vitronectin. This is an unusual phenomenon not previously observed with other normal cell types. The presence of cycloheximide inhibited this alternative attachment mechanism in corneal epithelial cells, indicating the role of newly synthesized proteins in this reaction. Additionally, we found that cell attachment to the polymer surface in the absence of cell-adhesive proteins was substantially inhibited by the presence of demecolcine, but not by cytochalasin B, thereby demonstrating the involvement of microtubules rather than actin microfilaments in this reaction. In the presence of serum-derived fibronectin and vitronectin, the attachment of corneal epithelial cells to a polymer may involve dual attachment mechanisms.