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Bai Alamusi, Toshihiko Matsuo, Osamu Hosoya, Kimiko M Tsutsui, Tetsuya Uchida; Vision recovery and retinal apoptosis reduction in RCS rats with Okayama University-type retinal prosthesis. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1800.
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© ARVO (1962-2015); The Authors (2016-present)
We are developing photoelectric dye-based retinal prosthesis (Okayama University type). We previously demonstrated that RCS rats with subretinal implantation with dye-coupled polyethylene film showed visual recovery on behavior tests in 8-week period after the implantation at 6 weeks of the age, compared with rats with plain film implantation. Furthermore, we discovered that neuronal apoptosis was reduced in the retina, apposed to the dye-coupled film, compared with the neighboring retina after 8 weeks of the implantation. In this study, we assessed the vision by behavior tests of RCS rats with the implantation at the elder age of 14 weeks and also analyzed apoptosis in the retina 5 months after the implantation.
Behavior tests were done in 10 RCS rats with no treatment at the age of 6, 8, 10, 12, and 14 weeks. At 14 weeks, 5 rats underwent subretinal implantation with dye-coupled films in both eyes while 5 rats underwent plain film implantation. Behavior tests were done in the 10 rats at the age of 16, 18, 20, and 22 weeks. After behavior tests at 22 weeks, the rats’ eyes were enucleated to confirm the film location. On the behavior test, a black-and-white-striped drum was rotated around a rat at 2 rpm, first clockwise for 3 min and then anticlockwise for 3min after 3-min rest. The head turn, consistent with the direction of drum rotation, was counted. As another series of experiments, apoptosis was detected in frozen sections of the eyes, enucleated 5 months after dye-film implantation at the age of 6 weeks in 2 RCS rats, and also after plain film implantation at 6 weeks in 2 rats.
By the histological evaluation, 3 rats were confirmed to have subretinal implantation of dye-coupled films and 3 rats to have subretinal implantation of plain films. The total number of head turn, in clockwise and anticlockwise drum rotation, increased significantly in 3 rats with dye-coupled films, compared with 3 rats with plain film implantation (repeat-measure ANOVA). In 2 rats with dye-coupled film implantation, the number of apoptotic cells was significantly reduced in the retina, apposed to the film, compared with the neighboring retina.
The vision of RCS rats was recovered by the dye-coupled film implantation even at the old age of 14 weeks. The apoptosis was reduced in the retina, apposed to the dye-coupled film, suggesting neuroprotection by the dye-coupled film.
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