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Joseph Hanna, Neeru Gupta, Xun Zhou, Emily Mathieu, Luz America Paczka-Giorgi, Yeni H Yucel; In Vivo Imaging of Blood Vessel Regression in Retinal Degeneration. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4440.
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© ARVO (1962-2015); The Authors (2016-present)
To non-invasively evaluate the retinal vessels of the Tie2-GFP mouse strain in vivo.
Homozygous (hm) Tie2-GFP mice retinas (JAX, USA) expressing green fluorescent protein (GFP) in their vascular endothelium with known retinal degeneration, were studied. Hm mice were crossed with CD1 mice (Charles River Laboratories, Canada) generating control heterozygous (ht) Tie2-GFP mice. Retinas of 12 (6M, 6F) hm Tie2-GFP were evaluated at 2 weeks (n=4), 3 months (n=4) and 8 months (n=4), and compared to control ht Tie2-GFP mice at the same time points (6M, 6F, n=12). Under isofluorane anesthesia, mouse retinas were imaged using blue Autofluorescence funduscopy (3 and 8 months) and 3D Optical Coherence Tomography (Spectralis, Heidelberg Engineering, Germany). 3D OCT was used to compare retinal thicknesses of hm and control mice. Histopathological validation was performed with isolectin/DAPI stained sections (Invitrogen, USA), imaged by confocal microscopy. Retinal thickness measured using OCT was compared between groups using t-test.
At 3 months, in vivo blue autofluorescent fundoscopy of hm Tie2-GFP mice showed fewer branching vessels compared to ht controls. (Fig. 1A-B). At 8 months, Tie2-GFP signal was not observed in main or branching vessels, compared to controls. At all-time points, retinal thicknesses of hm mice were significantly reduced compared to ht controls, with mean thicknesses of (163±6.6μm vs. 250.1±16μm), (94.3±8μm vs. 207.4±7.3μm) and (85.4±7.3μm vs. 208.75±7.8μm) (p<0.001) at 2 weeks, 3 and 8 months, respectively.At 2 weeks, Isolectin sections showed normal inner retinal vasculature in both hm mice and controls. At 3 months, hm mice retinas showed loss of deep vascular plexus, with degeneration of the photoreceptor and outer nuclear layers compared to age-matched ht controls. By 8 months, decreased isolectin staining had extended from the deep vascular plexus to intermediate and superficial plexuses compared to age-matched controls.
Non-invasive retinal imaging of a widely used hm Tie2-GFP mouse model showed blood vessel regression extending from deep to superficial plexuses. Further studies are needed to explore pathways and potential therapies to target angio-regression in retinal degenerations.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Figure 1. Fundus scans of homozygous (hm) Tie2-GFP mouse at 3 months shows reduced signal in main (arrows) and branching (arrowheads) vessels (A) compared to heterozygous (ht) control mouse (B).
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