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Background Neovascular glaucoma (NVG) is rare, comprising only 3.9% of all glaucoma cases. The most common cause of NVG is ischaemic central retinal vein occlusion (iCRVO). NVG frequently results in blindness and painful end-stage glaucomatous damage leading to the need for enucleation. Currently, there is no preventive therapy for NVG following iCRVO. Rescue treatments have severe drawbacks. Accordingly, there is a great need for preventing the often visually devastating outcomes of NVG. The STRONG study is designed to test whether the topically active anti-angiogenic agent aganirsen is able to inhibit the formation of neovascularisation leading to the development of secondary NVG in eyes with iCRVO. At the same time, STRONG will provide important information on the natural course of iCRVO and NVG in a large and well-characterised cohort of such patients. Methods/design This protocol describes a phase II/III, prospective, randomised, placebo-controlled, double-masked, three-armed multicentre study for the investigation of aganirsen, a new topical treatment for iCRVO in order to prevent NVG. The study will evaluate the efficacy of two different doses of this newly developed antisense oligonucleotide formulated in an eye emulsion to avoid new vessel formation by blocking insulin receptor substrate-1 (IRS)-1. This leads to subsequent down-regulation of both angiogenic as well as proinflammatory growth factors such as vascular endothelial growth factor (VEGF) and tumour necrosis factor (TNF). Eligible patients ( n  = 333) will be treated with topical aganirsen or placebo for a period of 24 weeks. They will also be invited to participate in substudies involving analysis of gonioscopic images, detection of biomarkers for NVG and risk factors for iCRVO. Discussion The STRONG study has the potential to offer a new treatment modality for patients suffering from iCRVO with a high risk of developing NVG. The topical administration can reduce patients’ burden and risk related to rescue treatment, such as destructive laser treatment or enucleation, but requires a high level of patient compliance. Trial registration EudraCT: 2014-000239-18; ClinicalTrials.gov, ID: NCT02947867 . (Registered on 15 October 2016); see also http://strong-nvg.com .

Angiogenesis, in which vascular endothelial growth factor receptor (VEGFR) 2 plays an essential role, is associated with a variety of human diseases including proliferative diabetic retinopathy and wet age-related macular degeneration. Here we report that a system of adeno-associated virus (AAV)-mediated clustered regularly interspaced short palindromic repeats (CRISPR)-associated endonuclease (Cas)9 from Streptococcus pyogenes (SpCas9) is used to deplete VEGFR2 in vascular endothelial cells (ECs), whereby the expression of SpCas9 is driven by an endothelial-specific promoter of intercellular adhesion molecule 2. We further show that recombinant AAV serotype 1 (rAAV1) transduces ECs of pathologic vessels, and that editing of genomic VEGFR2 locus using rAAV1-mediated CRISPR/Cas9 abrogates angiogenesis in the mouse models of oxygen-induced retinopathy and laser-induced choroid neovascularization. This work establishes a strong foundation for genome editing as a strategy to treat angiogenesis-associated diseases. Abnormal angiogenesis causes many ocular diseases. Here the authors employ CRISPR/Cas9 gene editing technology to silence VEGFR2, a major regulator of angiogenesis, in retinal endothelium and abrogate angiogenesis in the mouse models of oxygen-induced retinopathy and laser-induced choroid neovascularization.

Pathological angiogenesis (PA) contributes to various ocular diseases, including age-related macular degeneration, diabetic retinopathy, and retinopathy of prematurity, which are major causes of blindness over the world. Current treatments focus on anti-vascular endothelial growth factor (VEGF) therapy, but persistent avascular retina, recurrent intravitreal neovascularization, and general adverse effects are reported. We have previously found that recombinant thrombomodulin domain 1 (rTMD1) can suppress vascular inflammation. However, the function of rTMD1 in VEGF-induced PA remains unknown. In this study, we found that rTMD1 inhibited VEGF-induced angiogenesis in vitro. In an oxygen induced retinopathy (OIR) animal model, rTMD1 treatment significantly decreased retinal neovascularization but spared normal physiological vessel growth. Furthermore, loss of TMD1 significantly promoted PA in OIR. Meanwhile, hypoxia-inducible factor-1α, the transcription factor that upregulates VEGF, was suppressed after rTMD1 treatment. The levels of interleukin-6, and intercellular adhesion molecule-1 were also significantly suppressed. In conclusion, our results indicate that rTMD1 not only has dual effects to suppress PA and inflammation in OIR, but also can be a potential HIF-1α inhibitor for clinical use. These data bring forth the possibility of rTMD1 as a novel therapeutic agent for PA.

Angiogenesis is central to both normal and pathologic processes. Endothelial cells (ECs) express O-glycoproteins that are believed to play important roles in vascular development and stability. Endomucin-1 (EMCN) is a type I O-glycosylated, sialic-rich glycoprotein, specifically expressed by venous and capillary endothelium. Evidence has pointed to a potential role for EMCN in angiogenesis but it had not been directly investigated. In this study, we examined the role of EMCN in angiogenesis by modulating EMCN levels both in vivo and in vitro . Reduction of EMCN in vivo led to the impairment of angiogenesis during normal retinal development in vivo . To determine the cellular basis of this inhibition, gain- and loss-of-function studies were performed in human retinal EC (HREC) in vitro by EMCN over-expression using adenovirus or EMCN gene knockdown by siRNA. We show that EMCN knockdown reduced migration, inhibited cell growth without compromising cell survival, and suppressed tube morphogenesis of ECs, whereas over-expression of EMCN led to increased migration, proliferation and tube formation. Furthermore, knockdown of EMCN suppressed VEGF-induced signaling as measured by decreased phospho-VEGFR2, phospho-ERK1/2 and phospho-p38-MAPK levels. These results suggest a novel role for EMCN as a potent regulator of angiogenesis and point to its potential as a new therapeutic target for angiogenesis-related diseases.

Aim: To evaluate the safety and efficacy of surgical induction of chorioretinal venous anastomosis in the management of ischaemic central retinal vein occlusion (CRVO). Methods: In a comparative clinical trial, 28 patients with ischaemic CRVO were included, of whom 18 who declined surgery were considered as controls. The 10 surgical cases underwent standard vitrectomy with incisions into the choroids adjacent to the partially cut major retinal veins. Mersilene suture insertion was done to induce chorioretinal venous shunt. Mild endolaser was applied. Patients were followed up for 6–18 (mean 10) months. Results: Clinical success in shunt development was 90%. Surgical cases had a significantly better visual acuity improvement compared with controls (mean difference: 1.5 logMAR, p = 0.001) with 80% of them showing improvement (compared with 28% of the controls, p = 0.016). Neovascularisation developed in 39% of the control group compared with 0% of the surgical cases (p = 0.03). In multivariate analysis, surgery remained the sole significant predictor of visual improvement. There were three re-operations for vitreous cavity haemorrhage, cataract, and retinal detachment. Conclusions: Surgical induction of chorioretinal venous anastomosis may result in visual acuity improvement and prevent neovascularisation in ischaemic CRVO. Randomised studies are needed to compare the current study modality with the natural course of CRVO and emerging procedures, such as optic neurotomy, in the management of ischaemic CRVO.

Yuji Okuno et al . find that pathological angiogenesis in mice requires dampening of oxidative stress. In the absence of the ATM protein kinase, increased oxidative stress leads to activation of the p38α protein kinase and inhibition of new blood vessel growth. These findings run counter to the commonly held concept that decreasing oxidative stress would inhibit pathological angiogenesis and suggest new targets for treating diseases involving abnormal blood vessel growth. The ataxia telangiectasia mutated (ATM) kinase, a master regulator of the DNA damage response (DDR), acts as a barrier to cellular senescence and tumorigenesis. Aside from DDR signaling, ATM also functions in oxidative defense. Here we show that Atm in mice is activated specifically in immature vessels in response to the accumulation of reactive oxygen species (ROS). Global or endothelial-specific Atm deficiency in mice blocked pathological neoangiogenesis in the retina. This block resulted from increased amounts of ROS and excessive activation of the mitogen activated kinase p38α rather than from defects in the canonical DDR pathway. Atm deficiency also lowered tumor angiogenesis and enhanced the antiangiogenic action of vascular endothelial growth factor (Vegf) blockade. These data suggest that pathological neoangiogenesis requires ATM-mediated oxidative defense and that agents that promote excessive ROS generation may have beneficial effects in the treatment of neovascular disease.

Central retinal artery occlusion (CRAO) is an ophthalmic emergency and the ocular analogue of cerebral stroke. Best evidence reflects that over three-quarters of patients suffer profound acute visual loss with a visual acuity of 20/400 or worse. This results in a reduced functional capacity and quality of life. There is also an increased risk of subsequent cerebral stroke and ischaemic heart disease. There are no current guideline-endorsed therapies, although the use of tissue plasminogen activator (tPA) has been investigated in two randomized controlled trials. This review will describe the pathophysiology, epidemiology, and clinical features of CRAO, and discuss current and future treatments, including the use of tPA in further clinical trials.

: Pathological retinal angiogenesis with irregular and fragile vessels (also termed neovascularization, a response to hypoxia and dysmetabolism) is a leading cause of vision loss in all age groups. This process is driven in part through the energy deficiency in retinal neurons. Sustaining neural retinal metabolism with adequate nutrient supply may help prevent vision-threatening neovascularization. Low circulating serine levels are associated with neovascularization in macular telangiectasia and altered serine/glycine metabolism has been suggested in retinopathy of prematurity. We here explored the role of serine metabolism in suppressing hypoxia-driven retinal neovascularization using oxygen-induced retinopathy (OIR) mouse model. : We administered wild-type C57BL/6J OIR pups with systemic serine or provided the nursing dam with a serine/glycine-deficient diet during the relative hypoxic phase, followed by analysis of retinal vasculature at postnatal (P) 17, the time of peak neovascularization. Retinas from P17 OIR pups with either systemic serine supplementation or vehicle control were subjected to metabolomics, lipidomics, proteomics, and single-cell RNA sequencing. To validate the role of mitochondrial fatty acid oxidation (FAO) and oxidative phosphorylation (OXPHOS) in mediating serine protection against OIR, we treated OIR pups with inhibitors to block FAO or OXPHOS along with either serine or vehicle. The potential transcriptional mediator and pro-angiogenic signals were validated by western blotting. : Systemic serine supplementation reduced retinal neovascularization, while maternal dietary serine/glycine deficiency exacerbated it. FAO was essential in mediating serine protective effects, and serine supplementation increased levels of phosphatidylcholine, the most abundant phospholipids in the retina. Serine treatment a) increased the abundance of proteins involved in OXPHOS in retinas, b) increased the expression of mitochondrial respiration-related genes, and c) decreased the expression of pro-angiogenic genes in rod photoreceptor cluster. Serine suppression of retinal neovascularization was dependent on mitochondrial energy production. High mobility group box 1 protein (HMGB1) was identified as a potential key mediator of serine suppression of pro-angiogenic signals in hypoxic retinas. : Our findings suggest that serine supplementation may serve as a potential therapeutic approach for neovascular eye diseases by enhancing retinal mitochondrial metabolism and lipid utilization, suppressing the key drivers of uncontrolled angiogenesis.

Vascular networks develop from a growing vascular front that responds to VEGF and other guidance cues. Angiogenesis is required for normal tissue function, but, under conditions of stress, inappropriate vascularization can lead to disease. Therefore, inhibition of angiogenic sprouting may prevent neovascularization in patients with blinding neovascular eye diseases, including macular degeneration. VEGF antagonists have therapeutic benefits but also can elicit off-target effects. Here, we found that the Ras pathway, which functions downstream of a wide range of cytokines including VEGF, is active in the growing vascular front of developing and pathological vascular networks. The endogenous Ras inhibitor p120RasGAP was expressed predominately in quiescent VEGF-insensitive endothelial cells and was ectopically downregulated in multiple neovascular models. MicroRNA-132 negatively regulated p120RasGAP expression. Experimental delivery of α-miR-132 to developing mouse eyes disrupted tip cell Ras activity and prevented angiogenic sprouting. This strategy prevented ocular neovascularization in multiple rodent models even more potently than the VEGF antagonist, VEGF-trap. Targeting microRNA-132 as a therapeutic strategy may prove useful for treating multiple neovascular diseases of the eye and for preventing vision loss regardless of the neovascular stimulus.

Many neurodegenerative diseases are known to occur and progress because of oxidative stress, the presence of reactive oxygen species (ROS) in excess of the cellular defensive capabilities. Age related macular degeneration (AMD), diabetic retinopathy (DR) and inherited retinal degeneration share oxidative stress as a common node upstream of the blinding effects of these diseases. Knockout of the Vldlr gene results in a mouse that develops intraretinal and subretinal neovascular lesions within the first month of age and is an excellent model for a form of AMD called retinal angiomatous proliferation (RAP). Cerium oxide nanoparticles (nanoceria) catalytically scavenge ROS by mimicking the activities of superoxide dismutase and catalase. A single intravitreal injection of nanoceria into the Vldlr-/- eye was shown to inhibit: the rise in ROS in the Vldlr-/- retina, increases in vascular endothelial growth factor (VEGF) in the photoreceptor layer, and the formation of intraretinal and subretinal neovascular lesions. Of more therapeutic interest, injection of nanoceria into older mice (postnatal day 28) resulted in the regression of existing vascular lesions indicating that the pathologic neovessels require the continual production of excessive ROS. Our data demonstrate the unique ability of nanoceria to prevent downstream effects of oxidative stress in vivo and support their therapeutic potential for treatment of neurodegenerative diseases such as AMD and DR.