Assessment of epithelial restoration using limbal allograft transplantation in rabbit model with persistent corneal epithelial defect

Abstract

Purpose : Defects in corneal limbal epithelium can lead to persistent corneal epithelial defects (PECD), marked by chronic inflammation, neovascularization, scarring and conjunctivalization. A simple, reproducible and sustainable method for generation of animal models with PECD is necessary for assessing the new therapeutic modalities. The purpose of the study is to develop an animal model with PECD and to study epithelial regeneration potential of allogeneic simple limbal epithelial transplantation (allo-SLET) and conjunctival limbal allograft (CLAL).

Methods : Complete corneal and limbal epithelium of the New Zealand White Rabbit (n=10) was mechanically debrided using the Alger brush-II 1.0-mm round-ended burr after 360° Limbal peritomy. Rabbits were observed for corneal haziness, vascularization and epithelial defect using clinical photograph, slit lamp, fluorescein staining and anterior segment optical coherence tomography (AS-OCT) post debridement. At 4-8 week post debridement, allo-SLET without human amniotic membrane (n=5) and CLAL (n=5) was performed in the rabbit eyes with a donor graft obtained from the Dutch-Belted rabbit. The extent of epithelialization was assessed by change in the central corneal epithelial thickness (CCET) using AS-OCT.

Results : All eyes showed epithelial defect up to 4 weeks as evident by the fluorescein staining. In 70% (7/10) of the eyes superficial neovascularization was observed after 4 weeks of which 42% reached the central cornea. Epithelial defect was observed even after 5 weeks of debridement in 70% (7/10) of the eyes. Epithelial migration was observed from the transplanted grafts for up to 3 weeks in both the cases and graft were stable up to 3 months with no sign of epithelial rejection. Allo-SLET treated eye showed significant increase in CCET (P= 0.0255, n=5) as compared to CLAL (P > 0.5, n=5) at 3 month of transplantation.

Conclusions : Mechanical debridement using alger brush-II 1.0-mm round-ended burr is an effective method for the establishment of persistent corneal epithelial defect in New Zealand white rabbits. Limbal allograft transplantation lead to significant corneal epithelialization in PECD especially in allo-SLET.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.