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Eric Huy-Dang Nguyen, Min Jae Song, Russell Quinn, Tea Soon Park, Kapil Bharti; Hypoxia-induced Neovascularization in 3D Bioprinted Model of Outer Blood-Retinal Barrier. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4193.
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© ARVO (1962-2015); The Authors (2016-present)
Disrupted interactions between the retinal pigment epithelium (RPE) and underlying choroidal vasculature (CV) in the outer blood-retinal barrier (oBRB) is a driving force of macular degeneration. Hypoxia has been suggested as a dominant factor in stimulating exudative Age-related Macular Degeneration (wet AMD) via increased proangiogenic cytokine secretion from the basolateral region of RPE. This induces choroidal neovascularization and subsequent excessive angiogenic expansion of CV into the subretinal space. Currently, mechanisms of RPE/choroid interactions during wet AMD require clarification. We have developed a bioprinted 3D oBRB model to characterize RPE/choroid interactions in hypoxia-induced wet AMD and used Avastin, a known inhibitor of CNV to validate our wet AMD model.
The oBRB model consists of three layers: 1) a 3D bioprinted “choroid” consisting of endothelial cells, pericytes, and fibroblasts that self-assemble into microvasculature; 2) an electrospun sheet of poly(lactide-co-glycolide) nanofibers that provides mechanical support to the tissue; 3) a RPE monolayer that is formed on top of the nanofiber sheet. Hypoxia was induced in the engineered tissue model by apically treating RPE cells with ML228, an iron chelator. ML228 treatments were performed on either the bioprinted oBRB model and RPE monocultures on transwell inserts for 2 days followed by 12 days of ML228, Avastin, a DMSO vehicle control, or combined ML228/Avastin treatment.
ML228 treatment increased nuclear localization of Hypoxia-inhibitory Factor 1α (HIF-1α) and Vascular Endothelial Growth Factor (VEGF) secretion from the basolateral region of RPE. ML228 treatment drove angiogenic expansion of CV toward the RPE and decreased transepithelial resistance (TER) of RPE in the bioprinted oBRB model, suggesting RPE barrier disruption. ML228 treatment decreased TER in the RPE monoculture as well. Avastin, an anti-VEGF antibody, reduced CV expansion and partially rescued TER in the oBRB model. However, in RPE monocultures, Avastin did not rescue TER.
These results demonstrated that the oBRB model provides critical insights into RPE-choroid interactions that are expected to uncover target molecules for treating wetAMD. Avastin treatments in oBRB models and RPE monocultures highlight the need to better understand RPE/choroid interactions in the context of improving the effectiveness of AMD therapeutics.
This is a 2020 ARVO Annual Meeting abstract.
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