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AH Bruun, R Bragadottir, J Wasselius, K Narfstrom; Morphological Evidence for Successful Neuroretinal Transplantation in Abyssinian Cat Hereditary Retinal Degeneration . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3439.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To develop methods for allogenic retinal transplantation in the Abyssinian cat mutant, an animal model for human RP, using sheets of full-thickness neuroretina prepared in a physiologically optimized way. Methods: Ten 1-4 year old Abyssinian cats were used as recipients: 2 normal and 8 affected cats, the latter at an early stage of disease. Donor tissue was obtained from unrelated normal kittens, 4-18 days old, under dark adaptation. For preparation and storage of the tissue Ames´medium bubbled with 95% O2 and 5% CO2 was used. At the time of surgery donor neuroretina was dissected into a 2x4 mm piece and drawn into a glass micropipette. The surgical method used was as described for rabbit, but further developed for cat. Five of 10 transplanted eyes were studied morphologically at post-operative times: 1 mo (2 eyes), 3 mo (2 eyes) and 7 mo (1 eye). The eyes were transected at the ora, immersed into 4% formaldehyde at pH 7.4 in 0.1 M phosphate buffer, and rinsed in buffer with added sucrose of increasing concentrations (5-20%). Tissue specimens, including the transplant area, were prepared for cryostat sectioning and processed for hematoxylin-eosin and immunohistochemical staining. The following antibodies were obtained for immunohistochemistry studies, performed using methods previously described: synaptofysin, GFAP, NOS, recoverin, calbindin, PKC, parvalbumin, chat, GAD and Rho. Results: Nine of ten cats received transplants, visualized by ophthalmoscopy. One cat was euthanised due to massive intraocular hemorrhage during surgery. Using morphology all recipients showed viable transplants. Photoreceptor outer and inner segments had developed, in places donor outer segments were correctly positioned against the recipient RPE but in some areas there was also rosette formation. There were no signs of rejection but no definite signs of integration between recipient inner retina and donor tissue. Immunohistochemistry showed that the studied proteins were expressed normally in the donor tissue. Conclusion: Retinal transplantation in cat is technically difficult, but feasible. Normal young donor neuroretinal tissue in sheets develops, survive up to 7 months and become positioned against the RPE. It is at this time not clear if integration and neural contacts also occur between the transplant and the inner retina of the host, a prerequisite for visual function.
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