Recovery of Corneal Sensitivity, Calcitonin Gene-Related Peptide–Positive Nerves, and Increased Wound Healing Induced by Pigment Epithelial–Derived Factor Plus Docosahexaenoic Acid After Experimental Surgery

OBJECTIVE: To assess function of regenerated corneal nerves in correlation with epithelial wound healing after experimental nerve damage in rabbits treated with pigment epithelial-derived factor (PEDF) plus docosahexaenoic acid (DHA). METHODS: An 8-mm stromal dissection was performed in the right eyes of adult New Zealand rabbits. Treatment with PEDF+DHA was for 6 weeks. Corneal sensation was measured weekly by Cochet-Bonnet esthesiometer. After 8 weeks, immunofluorescence with βIII-tubulin, calcitonin gene-related peptide, and substance P antibodies was performed to quantify nerves. Also, rabbits were treated with PEDF+DHA for 4 weeks after lamellar keratectomy, followed by 8-mm epithelial debridement and epithelial defect assessment. One week after surgery, corneas were stained with anti-Ki67 antibody to assess cell proliferation. RESULTS: Eight weeks after surgery, calcitonin gene-related peptide-positive nerve fibers in the PEDF+DHA group were similar to normal rabbit corneas but were decreased in the vehicle. Substance P was localized in the subepithelial plexus but appeared in epithelial cells after nerve injury regardless of treatment. Five weeks after surgery, an increase in corneal sensitivity occurred in the PEDF+DHA group and reached normal values by 8 weeks. Pigment epithelial-derived factor plus DHA increased epithelial wound healing after lamellar keratectomy. One week after epithelial injury, Ki67-positive cells increased in the limbal area. CONCLUSION: Pigment epithelial-derived factor plus DHA promotes regeneration of calcitonin gene-related peptide-positive corneal nerves, accelerating wound healing and return of corneal sensitivity. CLINICAL RELEVANCE: Pigment epithelial-derived factor plus DHA represents a new approach to regenerate nerves and a potential treatment for prevention of severe dry eye after surgery or diseases of the ocular surface.