Purpose
The purpose of this study was to determine whether there are post-mortem changes in the structure of the limbal palisades in tissue preserved for corneal donation.
Methods
Four samples were obtained and 360 degree OCT volumes (Bioptigen) were acquired of the limbus daily. Volumes containing palisades were reconstructed and palisades were counted on enface volume projections and measured on axial slices taken from anterior, middle and posterior palisade regions.
Results
There are post-mortem changes in the structure of the palisades of Vogt in preserved tissue. The palisades diminish in number and size over time with changes beginning within 48 hours after death and continuing over the course of twelve days. By day 12 there are fewer palisades and their boundaries are less distinct. The length of the palisades diminishes over time and some disappear completely.
Conclusions
Post-mortem changes occur in the palisades of Vogt even when tissue is promptly harvested and maintained in nutrient-rich media. These changes may also reflect changes in the environment of the palisades and the cells therein which may have an influence on cadaveric limbal transplant success and may explain the rapid failure of the epithelium in preserved tissue.<br /> Tissue banking guidelines have been developed to optimize conditions for corneal buttons and endothelium, but not for stem cells or epithelium. Time is of the essence when epithelium is a concern, and this study indicates that palisades are also time dependent. In culture, most epithelial cells are lost by day four except those found on the basal layer, and further work is necessary to see if palisades and stem cells are most viable during that same window. The tissue preservation method, supported tissue versus submerged, organ culture vs optisol, or an alternate preservation media may also have bearing on the viability of the epitheilium and the palisades. It is also possible that biomechanical factors play a role in maintaining the niche.These findings may have significant implications for the timing of harvesting tissue for limbal transplantation as well as the use of cadaver tissue in laboratory studies.