Expression of Wnt and MMP in epithelial cells during corneal wound healing

To study the expression of Wnt during corneal wound healing and to understand the signaling mechanism involved.

Rat cornea was demarcated on the central area by 4-mm trepine, and the epithelium within this area was removed by scalpel. The epithelium was scraped and isolated to extract RNA. To determine the proliferation of corneal epithelial cells, corneoscleral rims from human donors were treated with dispase II for 15 minutes, and epithelial cells were isolated. Cells were plated on a 3T3 feeder cells layer. The proliferation of corneal epithelial cells was evaluated by colony-forming efficiency.

Wnt 5b and 7a were rapidly induced in wounded cornea, and Wnt 7a promoted proliferation of corneal epithelial cells. In addition, matrix metalloproteinase (MMP)-12 was expressed in wounded rat corneal epithelium. Transcription of MMP-12 was responsive to Wnt/beta-catenin signaling. Function blockade of MMP-12 delayed Wnt 7a-induced cell proliferation.

These results indicate that Wnt proteins and MMP-12 regulate the proliferation of corneal epithelial cells and that Wnt signaling contributes to the resurfacing of defective areas during corneal wound healing.