Effects of transforming growth factor β on corneal epithelial and stromal cell function in a rat wound healing model after excimer laser keratectomy

Abstract 

· Background: Transforming growth factor β (TGF-β) regulates extracellular matrix deposition, cell proliferation, and migration, and is expressed in cornea. TGF-β is thought to be involved in the corneal wound healing process. · Methods: The central corneal area (3 mm in diameter) of Lewis rats was ablated using PTK mode excimer laser and the wound healing process was observed at 12 and 24 h and 2, 5, 10, and 30 days after treatment. The expression of TGF-β1, -β2 and -β3, TGF-β type I and type II receptors, α3, α5, β4 integrin subunits, laminin and fibronectin was studied immunohistochemically. Antibody neutralizing TGF-β1, -β2 and -β3 was administered intraperitoneally, 50 µg daily, for 5 days after the laser treatment to investigate the effects of TGF-β function blockade. · Results: At the leading edge of the regenerating epithelium, no TGF-β type I and type II receptors and β4 integrin subunits were expressed after 24 h. Regenerating epithelium covered the ablated area after 2 days. An abnormal fibrotic layer was formed in the subepithelial area. This layer contained round-shaped cells in the stroma in the early stage (2–5 days after laser ablation) and spindle-shaped fibroblast-like keratocytes after 10 days. Laminin and fibronectin expression increased in the fibrotic layer. The increased stromal cells expressed TGF-β isoforms and TGF-β receptors. Neutralizing TGF-β inhibited the stromal cell increase in the laser ablated area after 5 days. · Conclusion: TGF-β may be involved in epithelial cell migration and stromal cell reaction during the corneal wound healing process after excimer laser ablation in rat models.