Abstract
Purpose :
A principal obstacle preventing successful whole eye transplantation (WET) is the preservation of retinal neurons, particularly retinal ganglion cells (RGCs). Preservation of other organs used in a majority of transplants has been achieved using University of Wisconsin cold storage solution (UWS). The efficacy of UW solution in preserving CNS tissue, including retina, has not been evaluated.
Methods :
Whole eyes were enucleated from mice and injected with either PBS or UWS. Some eyes were injected with UWS modified with BaCl2 and valproic acid, in order to counter early changes in RGCs caused by axotomy. Globes were then immersed in PBS or UWS and stored for up to 24 hrs at 4°C. Globes were evaluated by H&E staining, NFκB reporter transgene expression as an indicator of ischemia, and TUNEL. Retinal cell types were evaluated for abundance of cell-specific transcripts by qPCR. Whole retina electrophysiology experiments are planned.
Results :
Injection of both solutions prior to storage was critical to enhanced retinal preservation. PBS eyes exhibited edematous changes to all ocular compartments within 6 hrs, but particularly photoreceptor outer segments and the nerve fiber layer. Limbal scleral fibroblasts also exhibited NFκB activation. UWS eyes exhibited nearly pristine histology of all ocular compartments, including the retina, as late as 24 hrs. Neither solution elicited TUNEL staining or a change in lens opacity. Gross total RNA appeared intact in both PBS and UWS retinas (24 hrs), but PBS eyes exhibited a decrease in RNA amount as a function of wet tissue weight. Transcript abundance, relative to freshly prepared retina, showed an overall decrease in levels in eyes stored in both solutions, although UWS levels were statistically higher across the board. Amacrine cells faired the best in storage, while bipolar cells appeared most adversely affected. Some RGC-select genes (Sncg and Gap43) were the same or greater than levels in fresh retinal tissue.
Conclusions :
Baseline studies using UWS to preserve mouse eyes in preparation for WET prevented edema of ocular tissues. Molecular studies of retina, as a function of transcript levels, indicate significant beneficial effects on multiple cell types, including RGCs. This latter finding may facilitate increased regenerative potential of these cells. Functional testing is currently ongoing.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.