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John Mazzilli, Joshua Snook, Ken Simmons, Aleksey Domozhirov, Charles A Garcia, Rick Wetsel, Eva Zsigmond, Peter Westenskow; Preclinical Animal Safety Study with CR4-RPE Cells. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2446.
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There is an unmet need for treatments to halt progression of retinal degeneration in diseases such as age-related macular degeneration (AMD). One encouraging approach being tested is transplantation of exogenous RPE. Many independent groups, including ours, have shown that RPE can be derived efficiently from pluripotent stem cells. In this study, we derived retinal pigment epithelial (RPE) cells from a cell line we developed (CR-4), and are characterizing the cells and performing pharmacology trials in wild-type mice and in mice with inherited retinal degeneration. These studies are being performed in preparation for filing an investigative new drug (IND) application.
This study was conducted in accordance with the ARVO Statement for the Use of Animals in Ophthalmic and Vision Research. CR4-RPE cells were examined using ICC, gene-profiling to quantify expression of pluripotency and RPE specific markers, phagocytosis assays, and ELISA to quantify VEGF and PEDF expression. Mature CR4-RPE cells were subretinally injected in suspension in wild-type B6, MerTK-/-, and Elovl4-/- mice and examined at 5, 14, and 60 days post-injection (n=4—2males, 2 females) to evaluate survival and persistence of the cells in the subretinal space compared with sham injected and uninjected eyes. Animals were immunosuppressed with Cyclosporine A in the drinking water (210 mg/l) and observed daily for evidence of tumorigenesis, cataract formation, and behavioral changes. Optical Coherence Tomography (OCT) and histology were used to assess retinal integrity and evidence of inflammation and/or graft rejection. Ongoing analyses include functional rescue exams and necropsies on select tissues. Several animals were also injected to serve as open timepoints without immunosuppressive therapy.
OCT examinations show that the retinas reattach, CR4-RPE do not induce detrimental inflammatory effects, and do not generate neoplasms. No animals were lost during the study, and no incidence of uveitis or cataract formation was noted clinically during the study period. Non-native cells in the subretinal space at the retinal injection site were identified in histological examinations in all animals.
The preliminary results observed during this study show that CR4-RPE anatomically and functionally represent primary RPE and do not induce obvious detrimental effects in mice, we are now focused on performing remaining experiments necessary for IND approval.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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