Fucoidan Reduces Secretion and Expression of Vascular Endothelial Growth Factor in the Retinal Pigment Epithelium and Reduces Angiogenesis In Vitro

Michaela Dithmer,Elisabeth Richert,Johann Roider,Alexa Klettner,Harald Schmidt,Yang Shi,Sabine Fuchs,Ted S Acott

doi:10.1371/journal.pone.0089150

Abstract

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.

Highlights

Age-related macular degeneration (AMD) is the leading cause for legal blindness in the industrialized countries and, due to demographic developments, the burden of AMD will increase both as a clinical and as a socio-economical problem [1]
We investigated the effects of fucoidan on retinal pigment epithelium (RPE) cells physiology, RPE- derived vascular endothelial growth factor (VEGF) and RPE-induced angiogenesis
Similar results were obtained after 7 days, with no toxicity detected in ARPE-19 cells (99.72% (61.36)) and in primary porcine RPE cells (99.38% (6 0.93)) (Fig. 1C)

Summary

Introduction

Age-related macular degeneration (AMD) is the leading cause for legal blindness in the industrialized countries and, due to demographic developments, the burden of AMD will increase both as a clinical and as a socio-economical problem [1]. Wet, AMD, which is responsible for the majority of vision loss in AMD, choroidal neovascularizations (CNV) occur, in which vessels grow from the choroid into the subretinal and retinal space. These immature vessels leak into the retina, leading to vision loss or blindness [5]. Intravitreal injections are a considerable burden for the patient and the executive clinics [9]

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Results

Conclusion