Abstract
Purpose :
Diabetes damages corneal nerves, leading to diabetic keratopathy ( He J, and Bazan HEP. Ophthalmology 2012;119:956-964). Studies done in our laboratory have shown that in rabbits, PEDF in combination with DHA, stimulates corneal nerve regeneration, restores sensitivity and increases epithelial wound healing after experimental refractive surgery (Cortina MS, et al. Arch Ophthalmol. 2012; 130: 76-83). In the current study, we tested the effect of this treatment on corneal nerve regeneration in diabetic and non-diabetic mice after corneal injury.
Methods :
Normal and streptozomycin-induced diabetic mice (C57/B6) were anesthetized and the right eye was injured by removing the epithelium and 1/3 of the anterior stroma of a central area of 2mm diameter, using a corneal rust ring remover. Afterwards, both the diabetic and non-diabetic mice were randomly divided into two groups: Treatment groups received PEDF (0.4ng/10µl) + DHA (80ng/10µl) eyedrops topically 3 times a day for 2 weeks, while the control groups received the vehicle in the same way. Mice were euthanized and the whole corneas were immediately fixed and stained with rabbit monoclonal anti-PGP9.5 antibody. Whole-mount images were acquired to build an entire view of the corneal nerve architecture. The nerve fiber densities within the injured area (about 3.14 mm2 per cornea) were assessed on the basis of whole mount images by computer-assisted analysis.
Results :
Streptozomycin-treated mice showed a loss of corneal sensitivity when measured with a Cochet-Bonnet esthesiometer. Immediately after injury, immunofluorescence showed that all the subbasal nerve bundles, together with the anterior stromal nerve branches, were ablated. After two weeks, the nerve densities were 12.54±1.32% in the treatment group and 4.47±0.39% in the vehicle group. In non-diabetic mice, the nerve densities were 14.5±3.5% in the treatment group and 5.2±2.1% in the vehicle group.
Conclusions :
PEDF+DHA treatment promotes corneal nerve regeneration in both non-diabetic and diabetic mice. The mouse is an excellent model to study the mechanism of regeneration of corneal nerves affected by diabetes.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.