Adult rabbit retinal transplants

PURPOSE. To study the survival of adult retinal grafts prepared in a physio logically optimized way. METHODS. Twenty-three rabbits received an adult full-thickness rabbit retin al transplant positioned under the host retina, using a vitrectomy techniqu e. The transplants were prepared using a procedure based on a previously de scribed in vitro model used for physiological experiments on the adult reti na. Five rabbits received a fragmented graft. All grafts were prelabeled wi th 4', 6-diaminidin-2-phenylindoldihydrochloride (DAPI) to allow identifica tion. The eyes were examined by light and fluorescence microscopy 6 to 174 days after surgery. To assess the amount of cell death in the graft before actual transplantation, in vitro experiments were performed. The extent of cell death in retinas prepared by the optimized protocol was examined and c ompared with a simpler preparation previously used successfully for embryon ic grafts. The amount of cell death in the in vitro experiments was evaluat ed using a fluorescent green nucleic acid stain that penetrates dying cells . RESULTS. In 21 of the 23 animals that received full-thickness grafts prepar ed in an optimized way, the transplant survived. Sixteen grafts, including all four with a 174-day survival time, displayed normal morphology, with al l retinal layers preserved. The fragmented grafts survived poorly. The in v itro experiments showed minimal cell death in retinas prepared according to the optimized protocol, whereas control retinas displayed extensive cell d eath after 5 hours. CONCLUSIONS. The results showed that it is possible to transplant adult ret ina in the rabbit and that the grafts survive wen if they are prepared unde r physiologically optimized conditions and the integrity of the grafted tis sue is kept intact.