Abstract
Purpose::
To investigate the long-term feasibility of cultivated corneal endothelial cell transplantation in monkeys, whose corneal endothelial cells have low proliferative capacity in vivo.
Methods::
The experimental protocol was approved by the animal research committee of Shiga University of Medical Science, and animals were handled in accordance with ARVO guidelines. Monkey corneal endothelial cells (MCECs) from cynomolgous monkeys were cultivated on collagen type I carriers for 3 weeks, and used for transplantation. Under general anesthesia, the corneal endothelia of five eyes of five cynomolgous monkeys were scraped intensively. A 6-mm diameter disc of a cultivated MCEC sheet was then brought into the anterior chamber in three eyes of three monkeys and attached to Descemet’s membrane by air. As controls, a collagen sheet without MCECs was transplanted in one eye of one animal, and a suspension of cultivated MCECs was injected into the anterior chamber in one eye of one animal. Long-term observation by slit-lamp and specular microscopy was performed up to 18 moths post surgery. In two surgical eyes, microstructure of regenerated corneal endothelium was examined by electron microscopy at 6 months.
Results::
In all three surgical eyes, corneas became clear in two weeks and kept their clarity throughout the observation period. Control eyes, on the other hand, demonstrated irreversible bullous keratopathy. By electron microscopy, the endothelial surface was covered with a well-formed confluent layer of polygonal cells that ranged in size from 15-30 µm. Adjacent cells were closely attached with interdigitating junctions similar to normal corneal endothelium. By specular microscopy, we observed hexagonal cells at a density of 2200-2500 cells/mm2 2-4 months after surgery. Cell number steadily reduced thereafter, but stabilized at 1600 cells/mm2 (CV 0.35. hexagonality 57%) up to 18 months post-operatively.
Conclusions::
We have established a model of cultivated corneal endothelial transplantation using primates whose corneal endothelial cells, as in humans, do not proliferate in vivo. This is a useful model for long-term observation in advance of the future clinical application of cultivated corneal endothelial transplantation.
Keywords: cornea: endothelium • transplantation • wound healing