New insights into the proliferative capacities of rabbit corneal endothelial cells
Abstract
Purpose
Rabbits are known to have highly proliferative corneal endothelial cells (CECs) with excellent wound healing properties. Yet, little evidence of these capacities is available, except for 2 papers dating back to 1977 (PMID: 873721) and 1984 (PMID: 6511225).
Aim
To better characterize the proliferative capacity of rabbit CECs using labelling of mitosis and DNA synthesis and to search for potential stem cells.
Methods
Central corneal freezing (CF) was used on the right eye of young rabbits (4 weeks) with a brass bar soaked in liquid nitrogen. The thymidine analogue, 5-ethynyl-2′-deoxyuridine (EdU) was injected intraperitonealy at 0, 24 and 48 hours after CF. The corneal opacity was monitored using a slit lamp and corneal thickness using an AS-OCT. Rabbits were euthanatized 5 or 40 days after CF to label proliferating and slow cycling cells (presumed stem cells) using a Click-It EdU kit combined with Ki67 labeling. Both analyses were performed on flat mounted whole corneas to observe all CECs.
Results
Corneal opacity and thickness increased within 24 h after the CF. Both parameters returned to normal after 5 days. At 5 and 40 days the central endothelial cell density was normal. 266 ± 17 (1.7%) EdU positive CECs and/or 1532 ± 34 (5%) Ki67 positives CECs were observed, often grouped by pairs, in the endothelial periphery of the right eye as well as in the control eye. 14 ± 4 Ki67 positive cells (0.3%) were observed grouped by pairs in the central endothelium of the right eye.
Conclusions
In rabbit cornea, a few CECs are continuously spontaneously cycling at the periphery of the endothelium and all CECs may have the capacity to proliferate in response to injury, even in the centre.
