Purpose. Vascular endothelial growth factor (VEGF) antagonists are the therapy of choice for age-related macular degeneration. Ranibizumab and pegaptanib have been approved by the United States Food and Drug Administration, whereas bevacizumab is used off label. In this study, the authors compare these VEGF inhibitors directly regarding their efficiency to neutralize VEGF in a quantifiable in vitro system. methods. Porcine retina–retinal pigment epithelium–choroid organ culture and RPE cell culture were prepared from fresh eyes, cultivated in a perfusion chamber, and treated with clinically relevant concentrations of bevacizumab, ranibizumab and pegaptanib. VEGF content of the supernatant was analyzed with ELISA. Additionally, the influence of bevacizumab and ranibizumab on intracellular VEGF was analyzed with Western blot. results. At clinically significant doses, bevacizumab (0.25 mg/mL) and ranibizumab (0.125 mg/mL) neutralized VEGF completely for 6 hours, whereas pegaptanib (0.08 mg/mL) showed no effect. Bevacizumab and ranibizumab neutralized VEGF significantly up to 16 hours. When diluted, bevacizumab lost its inhibiting properties at a concentration of 975 ng/mL, and ranibizumab neutralized VEGF up to a concentration of 120 ng/mL. Both substances significantly diminished VEGF expression in Western blot. conclusions. At clinical doses, bevacizumab and ranibizumab are equally potent in neutralizing VEGF. To neutralize VEGF completely in this system, a fraction of the clinical dose is needed. Ranibizumab is more efficient at neutralizing VEGF when diluted. Pegaptanib showed no effect in this system, which might help explain the clinical experience regarding this drug. A direct effect of ranibizumab and bevacizumab on VEGF protein expression indicates additional pathways of VEGF inhibitors.

Fucoidan is a polysaccharide isolated from brown algae which is of current interest for anti-tumor therapy. In this study, we investigated the effect of fucoidan on the retinal pigment epithelium (RPE), looking at physiology, vascular endothelial growth factor (VEGF) secretion, and angiogenesis, thus investigating a potential use of fucoidan for the treatment of exudative age-related macular degeneration. For this study, human RPE cell line ARPE-19 and primary porcine RPE cells were used, as well as RPE/choroid perfusion organ cultures. The effect of fucoidan on RPE cells was investigated with methyl thiazolyl tetrazolium – assay, trypan blue exclusion assay, phagocytosis assay and a wound healing assay. VEGF expression was evaluated in immunocytochemistry and Western blot, VEGF secretion was evaluated in ELISA. The effect of fucoidan on angiogenesis was tested in a Matrigel assay using calcein-AM vital staining, evaluated by confocal laser scanning microcopy and quantitative image analysis. Fucoidan displays no toxicity and does not diminish proliferation or phagocytosis, but reduces wound healing in RPE cells. Fucoidan decreases VEGF secretion in RPE/choroid explants and RPE cells. Furthermore, it diminishes VEGF expression in RPE cells even when co-applied with bevacizumab. Furthermore, fucoidan reduces RPE-supernatant- and VEGF-induced angiogenesis of peripheral endothelial cells. In conclusion, fucoidan is a non-toxic agent that reduces VEGF expression and angiogenesis in vitro and may be of interest for further studies as a potential therapy against exudative age-related macular degeneration.

Background: Fucoidans are interesting for potential usage in ophthalmology, and especially age-related macular degeneration. However, fucoidans from different species may vary in their effects. Here, we compare fucoidans from five algal species in terms of oxidative stress protection and vascular endothelial growth factor (VEGF) interference in ocular cells. Methods: Brown algae (Fucus vesiculosus, Fucus distichus subsp. evanescens, Fucus serratus, Laminaria digitata, Saccharina latissima) were harvested and fucoidans isolated by hot-water extraction. Fucoidans were tested in several concentrations (1, 10, 50, and 100 µg/mL). Effects were measured on a uveal melanoma cell line (OMM-1) (oxidative stress), retinal pigment epithelium (RPE) cell line ARPE19 (oxidative stress and VEGF), and primary RPE cells (VEGF). Oxidative stress was induced by H₂O₂ or tert-Butyl hydroperoxide (TBHP). Cell viability was investigated with methyl thiazolyl tetrazolium (MTT or MTS) assay, and VEGF secretion with ELISA. Affinity to VEGF was determined by a competitive binding assay. Results: All fucoidans protected OMM-1 from oxidative stress. However, in ARPE19, only fucoidan from Saccharina latissima was protective. The affinity to VEGF of all fucoidans was stronger than that of heparin, and all reduced VEGF secretion in ARPE19. In primary RPE, only the fucoidan from Saccharina latissima was effective. Conclusion: Among the fucoidans from five different species, Saccharina latissima displayed the most promising results concerning oxidative stress protection and reduction of VEGF secretion.