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Kevin Emmerich, Liyun Zhang, Tim Mulligan, Meera Saxena, Jeff S Mumm; A Novel Model of Retinal Ganglion Cell Death and Regeneration in Zebrafish. Invest. Ophthalmol. Vis. Sci. 2020;61(7):2735.
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© ARVO (1962-2015); The Authors (2016-present)
Glaucoma is the second leading cause of blindness worldwide with 70 million people expected to be diagnosed by 2020. Degeneration of Retinal Ganglion Cells (RGCs), which send visual signals to the brain, is the hallmark feature underlying glaucoma along with optic nerve damage. We hypothesize that studying the cell death and regeneration of RGCs will lead to more understanding of glaucoma and facilitate discovery of therapeutic compounds to slow down cell death or enhance regeneration.
We have developed a transgenic zebrafish model that allows inducible and selective RGC death. This enables high through-put drug screening and high-resolution imaging in vivo and because zebrafish exhibit robust regeneration of RGCs, also allows interrogation of mechanisms regulating retinal regenerative potential. Our model is based on a newly improved NTR/prodrug cell ablation system that allows us to directly observe and quantify RGC loss and regeneration kinetics. Additionally, we have developed assays to measure vision in larval zebrafish to determine the effects of ablation and drug treatment.
Following a 24 hr treatment with a low dose of the prodrug metronidazole ~99.8% of RGCs are ablated. Four days following RGC loss, ~30% of RGCs have regenerated, providing a window to identify factors that either protect RGCs from induced cell death or modulate RGC regeneration rates. In a pilot compound screen, we have identified several neuroprotective compounds. Confocal time series microscopy confirms tectal innervation of regenerating RGCs and is being used to investigate interactions between dying RGCs, Müller glia (the resident stem cells of the zebrafish retina) and microglia (the resident macrophages of the retina). NTR-mediated ablation of RGCs also has a significant impact on visual function. Preliminary results suggest that RGC ablated fish show a marked deficit in adapting to a lighter background, suggesting profound visual deficits bordering on blindness.
We have developed a novel research model for study of RGCs that has potential therapeutic value in study of glaucoma. Our inducible model leads to selective cell death and visual deficits, that is followed by significant regeneration in zebrafish. This is readily amenable to high through-put compound testing and in vivo imaging.
This is a 2020 ARVO Annual Meeting abstract.
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