Effect of nerve growth factor on nerve regeneration in the rabbit cornea after lamellar keratoplasty

Abstract

Objective To discuss the effect of recombinant human type Ⅲ collagen (RHC-Ⅲ)with nerve growth factor (NGF) on nerve regeneration after transplanting it into the rabbit cornea.Methods This was an experimental study. Sixteen rabbits were randomly divided into group A and group B, 8 rabbits in each group. The right eyes were the experimental eyes. RHC-Ⅲ with 5 ng/mg NGF and RHC-Ⅲ without NGF were implanted into the anterior lamella of the rabbit corneas in each group. One cornea was randomly selected at the 2nd week, 1st month, 3nl month and 6th month after surgery. Photochemical gold chloride impregnations were performed and the regeneration of corneal nerves was observed under light microscopy. The number of the nerve fibers in the corneal epithelium and anterior lamellar layer were calculated at all the time points. Independent samples t test was used to compare the number of fibers for the two groups. Results Nerve staining showed that nerve regeneration was already taking place in the corneal epithelium and anterior lamellar layer in both groups at the 2nd week. At the 1st month, some regenerated nerve fibers in the superficial stroma had formed a network. At the 3rd month, the number of regenerated nerve fibers had noticeably increased in both groups and more networks and lateral branches had formed.Six months later, there were a greater number of regenerated nerve fibers in group A compared to group B, and the structures in group A were more normal. However, some nerve fibers did not regenerate in either group. The numbers of regenerated nerve fibers at the four time points were (6.80±0.84), (11.80±1.10), (25.20±1.30), (42.40±1.82) per 100 times the microscopic field in group A; and (3.00±0.71), (5.80±0.84), (13.20±0.84), (26.60±1.14) per 100 times the microscopic field in group B. There were significant differences in the number of nerve fibers between group A and group B at all the observation points (t=7.76, 9.73, 17.32, 16.47, P＜0.01 for all).Conclusion NGF can improve nerve regeneration in the rabbit cornea after lamellar keratoplasty. Key words: Nerve growth factor; Collagen, recombinant human type Ⅲ; Corneal transplantation; Nerve regeneration