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C. A. Mamalis, L. Luo, S. A. Molokhia, K. Jackman, M. Romanowski, B. K. Ambati; Ocular Bioimaging of a Murine Model of Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6145.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if anti-Vascular Endothelial Growth Factor antibody fragments (fabs) conjugated with Indocyanine Green (ICG) and gold nanorods reveal the presence of subretinal injection -induced choroidal neovascularization (CNV) in a murine model.
Using the Thermo Scientific Fab Preparation kit (#44885), anti- mouse VEGF IgG underwent papain digestion into Fab fragments which were isolated from the remaining IgG and Fc particles. Purified Fab fragments were lyophilized and conjugated to ICG and aminated gold nanorods in separate aliquots. The prepared bioconjugates were combined and injected systemically into the tail vein of Balb/C mice which had previously been injected with AAV.siRNA.sFlt to induce CNV. The posterior segment was evaluated using Ocular Coherence Tomography (OCT) and ICG imaging capabilities of the Heidelberg Spectralis. Images were obtained immediately, 2 hours, 4 hours, 24 hours, and 2 weeks post injection, for evidence of contrast indicating focally elevated concentrations of VEGF.
The bioconjugation of ICG and gold nanorods as contrast agents to anti-VEGF Fab fragments successfully identified regions of CNV (a model of exudative macular degeneration) induced via subretinal injection in Balb/C mice. The ICG images revealed a localized signal 2 and 4 hours post injection highlighting areas of suspected CNV. OCT images were then obtained immediately in the same location in order to confirm that areas highlighted by the ICG bioconjugate were in fact areas of CNV. The OCT images confirmed that the anti-VEGF-Fab-ICG bioconjugate was in areas of induced CNV. ICG became visible in the vasculature 2 hours post injection and remained until 4 hours post-injection. The localized ICG signal faded within 24 hours after injection.
ICG-anti-VEGF-fab and anti-VEGF-fab-nanorod bioconjugates highlighted regions of CNV in a murine model. Using novel bio-conjugated markers with SLO technology could provide convenient detection of VEGF elevation, a key pathogenic event in age-related macular degeneration, perhaps before neovascularization has caused clinical damage.
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