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Zsolt Ablonczy, Christopher Schillo, David A Hollander, Andy Whitlock; Quantitation of fibrosis in a rat model of laser-induced CNV. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1256.
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© ARVO (1962-2015); The Authors (2016-present)
Choroidal neovascularization (CNV), secondary to age-related macular degeneration (AMD), is a common cause of severe vision loss. The laser-induced rodent model of CNV recapitulates fibrovascular manifestations of the disease well enough to be valuable for screening clinically beneficial compounds. Based on this model, the purpose of this study was to develop a robust tool for testing the efficacy of anti-fibrotic agents in the treatment of wet AMD.
Brown-Norway rats received either oral vehicle or pazopanib for 17 days. On day 3, four lesions (200 µm, 100 ms, 200mW) were burned within two discs from the right optic nerve head in each rat using a 532 nm laser attached to a Micron III camera. Fundus imaging and OCT verified the lesions. On days 10 and 17, FA and OCT assessed leakage and lesion volume. Enucleated eyes were prepared for histology and sections were cut from the right of the most temporal lesion to the left of the most nasal lesion. With 3 consecutive 8 μm sections per row and then skipping 7 before the next row, 30 rows of sections per eye were collected, and trichrome stained. The two central sections of each lesion were digitized. The same size area around lesions was analyzed for the presence of fibrosis (as % area) using a custom ImageJ macro, adapted from (Hypertension. 2006;47:488-495).
Compared to vehicle, pazopanib induced a highly significant decrease in both lesion leakage and volume (p<0.001 and p<0.0001, respectively) on both day 10 and day 17. On day 17, the fibrotic area around vehicle-treated lesions was significantly higher (p<0.003) compared to lesions in pazopanib-treated animals or same size non-lasered areas. Repetition of the procedure resulted in similar results in terms of the significance, amplitude, and numerical values of the differences between these two groups.
These data provided evidence that pan-tyrosine kinase inhibition was beneficial for ameliorating laser induced CNV in this rat model, as seen in reduction of leakage, size of lesion, and fibrotic activity. A strong, quantitative agreement of results from repeated experiments underlined the robustness of this tool for reliably assessing fibrosis. These data pave the way to screening anti-fibrotic medications for the treatment of angiogentic eye disorders.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
A, Images of CNV lesions (top row) and corresponding fibrotic areas (bottom row) in vehicle- and pazopanib treated rats. B, Fibrosis quantitation.
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