Abstract
Abstract: :
Purpose: To study the development and survival of cultured full–thickness neuroretina after transplantation. Methods: Five E50 fetuses from a normal pig were taken out by caesarian section. Eight eyes were enuceated and immersed in CO2–independent medium. The anterior segment was removed and the neuroretina dissected free. One neuroretina was fixed directly as control. The remaining 7 neuroretinas were explanted on Millicell'–PCF 0,4mm culture plate inserts with the photoreceptor layer facing the membrane. The retinas were kept in vitro under standard culture conditions. The cultured explants were divided into 2 groups. The first group (n=4) of neuroretinas was kept in culture 1 day, and the second (n=3) for 3 days. After culturing, the retinas were transplanted to the subretinal space of 7 normal adult pig by means of a vitrectomy and retinotomy. After a survival of 3 months (84 – 86 days) the eyes were enucleated and processed for routine and and immunohistochemistry. Antibodies against transducin (cones), recoverin (cones and rods), and PKC (rod bipolar cells) were used. Results: The immediately fixed E50 fetal neuroretina consisted of a ganglion cell layer, an inner plexiform layer and two nuclear layers separated by the outer plexiform layer. Transplanted cultured retinas, after 3 months, displayed the normal retinal lamination, except for in two transplants consisting mostly of rosettes and degenerating tissue. The 5 laminated transplants had developed all retinal layers including well developed photoreceptors with inner segments. One of these grafts was found upside–down with inner layers facing the host retinal pigment epithelium (RPE). The remaining 4 transplants displayed normal polarity, and contained short outer segments facing the host RPE. Immunolabeling with transducin, recoverin and PKC showed labeling of photoreceptors and bipolar cells in the transplants comparable to the normal porcine retina. Conclusion: To our knowledge, this is the first study describing transplantation of cultured neuroretinal tissue. The majority of grafts retained their normal laminated structure with well developed layers including photoreceptor outer segments even after 3 days in vitro prior to transplantation. This indicates a possibility to safely store donor tissue between harvest and actual transplantation. The culture system may also in the future be used as a tool for manipulating retinal donor tissue prior to transplantation.
Keywords: transplantation • retinal culture • retinal development