Intravitreal AAV2.COMP-Ang1 Attenuates Deep Capillary Plexus Expansion in the Aged Diabetic Mouse Retina

Abstract

PURPOSE. We determine whether intravitreal angiopoietin-1 combined with the short coiledcoil domain of cartilage oligomeric matrix protein by adeno-associated viral serotype 2 (AAV2.COMP-Ang1) delivery following the onset of vascular damage could rescue or repair damaged vascular beds and attenuate neuronal atrophy and dysfunction in the retinas of aged diabetic mice. METHODS. AAV2.COMP-Ang1 was bilaterally injected into the vitreous of 6-month-old male Ins2 Akita mice. Age-matched controls consisted of uninjected C57BL/6J and Ins2 Akita males, and of Ins2 Akita males injected with PBS or AAV2.REPORTER (AcGFP or LacZ). Retinal thickness and visual acuity were measured in vivo at baseline and at the 10.5-month endpoint. Ex vivo vascular parameters were measured from retinal flat mounts, and Western blot was used to detect protein expression. RESULTS. All three Ins2 Akita control groups showed significantly increased deep vascular density at 10.5 months compared to uninjected C57BL/6J retinas (as measured by vessel area, length, lacunarity, and number of junctions). In contrast, deep microvascular density of Ins2 Akita retinas treated with AAV2.COMP-Ang1 was more similar to uninjected C57BL/6J retinas for all parameters. However, no significant improvement in retinal thinning or diabetic retinopathy-associated visual loss was found in treated diabetic retinas. CONCLUSIONS. Deep retinal microvasculature of diabetic Ins2 Akita eyes shows late stage changes consistent with disorganized vascular proliferation. We show that intravitreally injected AAV2.COMP-Ang1 blocks this increase in deep microvascularity, even when administered subsequent to development of the first detectable vascular defects. However, improving vascular normalization did not attenuate neuroretinal degeneration or loss of visual acuity. Therefore, additional interventions are required to address neurodegenerative changes that are already underway.

Dual-Acting Antiangiogenic Gene Therapy Reduces Inflammation and Regresses Neovascularization in Diabetic Mouse Retina

“…These results are similar to those described by Carroll et al. 54 in a study with 10.5-month-old Ins2 Akita mice. The contradictory results could be because of the discrepancy in the age of the animals analyzed, because most reports do not go beyond 6 months of hyperglycemia, the time at which the first signs of vascular damage are visible.…”

“…These results are in accordance with studies performed in 9- and 10.5-month-old animals. 54 , 55 Therefore, in this work, we aimed to restore the retinal network physiopathology by restoring the balance between players of angiogenesis, through the upregulation of PEDF and silencing of PlGF. The potent anti-angiogenic action of PEDF in combination with its anti-inflammatory and neuroprotective effects has been shown to have protective effects against retinal cell death.…”

Intracameral Injection of AAV-DJ.COMP-ANG1 Reduces the IOP of Mice by Reshaping the Trabecular Outflow Pathway

“…Intravitreal injection of AAV2.COMP-ANG1 could attenuate retinal neovascularization and strengthen vascular barrier function in a diabetic mouse model. 48 , 49 In quiescent vasculature, however, systemic administration of Ad.COMP-ANG1 induces long-lasting vessel enlargement and increased blood flow by promoting endothelial proliferation. 50 Consistent with former reports, we observed significant SC enlargement and amplified aqueous outflow in AAV-DJ.COMP-ANG1–treated eyes reflecting the vascular/lymphatic hybrid nature of SC.…”

AAV-Based Strategies for Treatment of Retinal and Choroidal Vascular Diseases: Advances in Age-Related Macular Degeneration and Diabetic Retinopathy Therapies

“…A single intravitreal injection of this therapy at 2E9 vg was administered to diabetic Ins2Akita mice at an early stage of DR and improved vascular structure, visual function, and BRB integrity [ 127 ]. The same group later injected this therapy in animals with vascular damage resulting from the same disease model but at a more advanced stage [ 129 ]. Despite preventing proliferative vascular retinopathy, this therapy could not ameliorate neuroretina degeneration and visual function, suggesting the involvement of other processes, besides vascularity, in neuronal cell loss.…”