Involvement of stem cell factor and c-kit in corneal wound healing in mice

PURPOSE To study the roles played by stem cell factor (SCF) and SCF receptor c-kit in wound healing of corneal epithelial cells. METHODS A 2 mm corneal epithelial wound was made in control (WBB6F1(+/+)), SCF (Sl/Sl(d))-, and c-kit (W/W(v)) mutant mice, and the speed of wound healing, 5-bromo-2'-deoxyuridine (BrdU) incorporation, and scanning electron microscopic (SEM) morphology of the corneas were examined. The incorporation of BrdU and the degree of cell attachment in cultured mouse corneal epithelial cells (MCECs) isolated from WBB6F1(+/+), Sl/Sl(d), and W/W(v) mice were examined. Cultured immortalized human corneal epithelial cells (HCECs) were examined by a cell attachment assay after their exposure to anti-SCF antibodies, tyrosine kinase inhibitor (genistein), and competitive Arg-Gly-Asp (RGD) peptide, as well as on cultures treated with extracellular matrix. RESULTS The speed of corneal wound healing was slower in Sl/Sl(d) and W/W(v) mice than in controls (p<0.01) and the speed of healing in Sl/Sl(d) mice recovered after topical application of SCF (8 ng/ml). No significant difference was found in the BrdU incorporation assay either in vivo or in vitro. Loosened epithelial cells were detected at wound margins in W/W(v) mice by SEM. The cell attachment rate was increased by 157% in cells from WBB6F1(+/+) and 252% in Sl/Sl(d) MCECs by recombinant mouse SCF; however, no significant difference was found in W/W(v) MCECs. Anti-SCF antibodies (Ab), genistein, and RGD peptide reduced the percentage of attached HCECs. Anti-SCF Ab inhibited the attachment of HCECs on fibronectin, laminin, or type IV collagen coated dishes. CONCLUSIONS These findings indicate that the SCF/c-kit system may play a role in corneal wound healing through epithelial cell attachment.