Background Ranibizumab — a recombinant, humanized, monoclonal antibody Fab that neutralizes all active forms of vascular endothelial growth factor A — has been evaluated for the treatment of neovascular age-related macular degeneration. Methods In this multicenter, 2-year, double-blind, sham-controlled study, we randomly assigned patients with age-related macular degeneration with either minimally classic or occult (with no classic lesions) choroidal neovascularization to receive 24 monthly intravitreal injections of ranibizumab (either 0.3 mg or 0.5 mg) or sham injections. The primary end point was the proportion of patients losing fewer than 15 letters from baseline visual acuity at 12 months. Results We enrolled 716 patients in the study. At 12 months, 94.5% of the group given 0.3 mg of ranibizumab and 94.6% of those given 0.5 mg lost fewer than 15 letters, as compared with 62.2% of patients receiving sham injections (P<0.001 for both comparisons). Visual acuity improved by 15 or more letters in 24.8% of the 0.3-mg group and 33.8% of the 0.5-mg group, as compared with 5.0% of the sham-injection group (P<0.001 for both doses). Mean increases in visual acuity were 6.5 letters in the 0.3-mg group and 7.2 letters in the 0.5-mg group, as compared with a decrease of 10.4 letters in the sham-injection group (P<0.001 for both comparisons). The benefit in visual acuity was maintained at 24 months. During 24 months, presumed endophthalmitis was identified in five patients (1.0%) and serious uveitis in six patients (1.3%) given ranibizumab. Conclusions Intravitreal administration of ranibizumab for 2 years prevented vision loss and improved mean visual acuity, with low rates of serious adverse events, in patients with minimally classic or occult (with no classic lesions) choroidal neovascularization secondary to age-related macular degeneration. (ClinicalTrials.gov number, NCT00056836.)

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Ranibizumab for Neovascular Age-Related Macular Degeneration

The establishment of a vascular supply is required for organ development and differentiation as well as for tissue repair and reproductive functions in the adult1 Neovascularization (angiogenesis) is also implicated in the pathogenesis of a number of disorders These include: proliferative retinopathies, age-related macular degeneration, tumors, rheumatoid arthritis, and psoriasis1,2 A strong correlation has been noted between density of microvessels in primary breast cancers and their nodal metastases and patient survival3 Similarly, a correlation has been reported between vascularity and invasive behavior in several other tumors4–6

The biology of vascular endothelial growth factor

https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(12)60028-2.pdf

Embryonic stem cell trials for macular degeneration: a preliminary report

Vascular endothelial growth factor (VEGF) is a fundamental regulator of normal and abnormal angiogenesis. Recent evidence indicates that VEGF is essential for embryonic vasculogenesis and angiogenesis. Furthermore, VEGF is required for the cyclical blood vessel proliferation in the female reproductive tract and for longitudinal bone growth and endochondral bone formation. Substantial experimental evidence also implicates VEGF in pathological angiogenesis. Anti-VEGF monoclonal antibodies or other VEGF inhibitors block the growth of many tumor cell lines in nude mice. Furthermore, the concentrations of VEGF are elevated in the aqueous and vitreous humors of patients with proliferative retinopathies such as the diabetic retinopathy. In addition, VEGF-induced angiogenesis results in a therapeutic benefit in several animal models of myocardial or limb ischemia. Currently, both therapeutic angiogenesis using recombinant VEGF or VEGF gene transfer and inhibition of VEGF-mediated pathological angiogenesis are being pursued.

Molecular and biological properties of vascular endothelial growth factor.

Evidence accumulating over the last decade has established the fundamental role of vascular endothelial growth factor (VEGF) as a key regulator of normal and abnormal angiogenesis. The biological effects of VEGF are mediated by two tyrosine kinase receptors, Flt-1 (VEGFR-1) and KDR (VEGFR-2). The signaling and biological properties of these two receptors are strikingly different. VEGF is essential for early development of the vasculature to the extent that inactivation of even a single allele of the VEGF gene results in embryonic lethality. VEGF is also required for female reproductive functions and endochondral bone formation. Substantial evidence also implicates VEGF as an angiogenic mediator in tumors and intraocular neovascular syndromes, and numerous clinical trials are presently testing the hypothesis that inhibition of VEGF may have therapeutic value.

https://www.physiology.org/doi/pdf/10.1152/ajpcell.2001.280.6.C1358

Role of vascular endothelial growth factor in regulation of physiological angiogenesis

Subfoveal fibrovascular membranes in age-related macular degeneration express vascular endothelial growth factor

Purpose. Vascular endothelial growth factor (VEGF) is a potent and specific angiogenic growth factor, in vitro and in vivo, that may be associated with the development of intraocular neovascularization. In the current study, the authors analyze the expression of VEGF in subfoveal fibrovascular membranes from patients with age-related macular degeneration. Methods. Surgically removed subfoveal fibrovascular membranes from 18 eyes were analyzed for the expression of VEGF mRNA and protein using in situ hybridization and immunohistochemistry, respectively. Results. Most specimens expressed both VEGF mRNA and protein. The VEGF mRNA expression was particularly high in areas with a marked inflammatory response, in which the expression was concentrated to cells resembling fibroblasts and to surrounding inflammatory cells. VEGF protein expression was seen in fibrovascular parts of the membranes and was predominantly localized to the cytoplasm of fibroblastlike cells. In some of these membranes, strong VEGF protein immunoreactivity also was concentrated to extracellular matrix foci within the fibrovascular stroma. Conclusions. Results indicate that VEGF may be of pathogenetic importance for the development of the choroidal neovascularization (age-related macular degeneration) and also may implicate a role of fibroblasts of presumable choroidal origin in this process.

Subfoveal fibrovascular membranes in age-related macular degeneration express vascular endothelial growth factor.

Photochemical damage of the retina.

The pathogenesis of age-related maculopathy (ARM), the most common cause of visual loss after the age of 60 years, is indeed a complicated scenario that involves a variety of hereditary and environmental factors The pathological cellular and molecular events underlying retinal photochemical light damage, including photoreceptor apoptosis, have been analysed in experimental animal models Studies of age-related alterations of the retina and photoreceptors, the accumulation of lipofuscin in retinal pigment epithelium (RPE) cells, and the formation of drusen have greatly contributed to our knowledge A new concept of an inflammatory response to drusen has emerged, suggesting immunogenic and systemic reactions in Bruch's membrane and the subretinal space Oxidative stress and free radical damage also impact on the photoreceptors and RPE cells in the ageing eye Based on the photoelectric effect, a fundamental concept in quantum physics, the consequences of high-energy irradiation have been analysed in animal models and cell culture Short-wavelength radiation (rhodopsin spectrum), and the blue light hazard (excitation peak 440 nm), have been shown to have a major impact on photoreceptor and RPE function, inducing photochemical damage and apoptotic cell death Following cataract surgery, there is a dramatic change in ocular transmittance In aphakic or pseudophakic eyes (with clear intraocular lenses), high-energy (blue) and ultraviolet-A radiation strikes the retina Epidemiological data indicate a significantly increased 5-year incidence of late ARM in non-phakic eyes compared with phakic eyes In recent years, putative prophylactic measures against ARM have emerged The implantation of 'yellow' intraocular lenses (IOLs) that absorb high-energy blue radiation is, from a theoretical point of view, the most rational approach, and, from a practical point of view, is easy to accomplish With increasing age, RPE cells accumulate lipofuscin (chromophore A2E) It is noteworthy that the yellow IOL not only protects A2E-laden human RPE cells from blue light (peak 430 nm) damage, but also alleviates the detrimental effects of green (peak 550 nm) and white light A prophylactic treatment using antioxidants is aimed at counteracting oxidative stress and free radical cellular damage The Age-Related Eye Disease Study (AREDS), a randomized clinical trial, showed a significantly lower incidence of late ARM in a cohort of patients with drusen maculopathy treated with high doses of antioxidants than in a placebo group In recent years, considerable progress in retinal research has been achieved, creating a platform for the search for new prophylactic and therapeutic measures to alleviate or prevent photoreceptor and RPE degeneration in ARM

/pdf/age-related-maculopathy-and-the-impact-of-blue-light-hazard-1et3mhrmru.pdf

Age-related maculopathy and the impact of blue light hazard.

Background: Age-related macular degeneration (ARMD) is caused by abnormal retinal pigment epithelium (RPE) and may be complicated by choroidal neovascularization. The object of treatment would be to replace the diseased RPE with normal human RPE. • Method: Five patients with ARMD (preoperative visual acuity 0.08–0.2) underwent removal of subretinal fibrovascular membranes using pars plana vitrectomy techniques. Human fetal RPE (15–17 weeks gestational age) was cultured and transplanted as a monolayer patch into the subretinal space. Transplants were followed by funduscopy and fluorescein angiography. Macular function was assessed using scanning laser ophthalmoscopic (SLO) microperimetry. • Results: Three RPE transplants were placed in the fovea; two were placed parafoveally. All transplants have survived for 3 months. They have grown and increased in size covering part of the epithelial defect caused by removal of the fibrovascular membrane. SLO microperimetry indicated that visual function was present in four of the transplants at 1 month but in only two at 3 months after surgery. Function over the transplants, especially those in the fovea, was compromised by cystoidlike macular edema. • Conclusions: Human fetal RPE transplants survive well in the macula for as long as 3 months. They are capable of growing to cover epithelial defects caused by removal of subretinal neovascular membranes. The causes for development of macular edema in transplants directly in the fovea warrant further evaluation.

Peep V. Algvere

Papers

Subfoveal fibrovascular membranes in age-related macular degeneration express vascular endothelial growth factor

Subfoveal fibrovascular membranes in age-related macular degeneration express vascular endothelial growth factor.

Photochemical damage of the retina.

Age-related maculopathy and the impact of blue light hazard.

Transplantation of fetal retinal pigment epithelium in age-related macular degeneration with subfoveal neovascularization.