A rabbit model for corneal endothelial dysfunction

Abstract

Purpose: The endothelium is a monolayer on the inner cornea to maintain transparency. Loss of function due to dystrophy, trauma or genetic disease leads to edema, pain and loss of vision. While the current treatment is limited to endothelial or penetrating keratoplasty, cell therapy approaches are being studied and there is a clear need for an animal model of corneal edema for pre-clinical studies. Here we describe a rabbit model for surgically-induced corneal edema and the dynamics of endothelial recovery after injury and after injection of human corneal endothelial cells (HCECs).

Methods: 22 New Zealand White female rabbits underwent 3 mm corneal endothelium/Descemet’s membrane debridement followed by HCEC or vehicle injection. HCECs (200,000 cells) or control vehicle (BSS+) were injected into the anterior chamber immediately. To improve HCEC’s integration to the host endothelium, HCECs were loaded with magnetic nanoparticles prior to injection, and pulled towards the front of the eye with an external magnet. Central corneal thickness and intraocular pressure were measured daily for the first 3 postoperative (PO) days and weekly thereafter. Animals were euthanized at 7 and 28 PO days, and eyes examined with hematoxylin-eosin. Immunohistochemistry using anti-human antigen antibodies was performed to distinguish HCEC integration from host endothelial cells.

Results: Immediately after endothelial debridement, central corneal thickness increased in all animals. Eyes treated with HCECs recovered faster than controls without changes in the intraocular pressure. Decrease in corneal thickness observed by pachymetry was confirmed by subsequent histological analysis. At 28 days, the thickness of HCEC-injected corneas was comparable to that of the intact contralateral eye; control BSS+-treated corneas remained thicker. Histologically and with immunofluorescence, we found clumps of donor cells re-populating the stripped endothelial regions. No acute or early inflammatory response was observed in any of the treated corneas.

Conclusions: This pilot study revealed that injection of magnetic HCECs may be a safe therapy for the treatment of corneal endothelial dysfunction. Future studies will focus on the optimal dose and delivery method to enhance integration of the injected HCECs into the host endothelium, and address long-term toxicity. Overall, these preliminary results encourage further efforts on using magnetic HCECs as an approach to treat corneal edema.

Keywords: 481 cornea: endothelium • 505 edema • 620 ocular irritancy/toxicity testing