Research Article Zeaxanthin Inhibits Hypoxia-Induced VEGF Secretion by RPE Cells through Decreased Protein Levels of Hypoxia-Inducible Factors-1 Richard Rosen, 1,2 Tommaso Vagaggini, 3 Yueqin Chen, 3 and Dan-Ning Hu 1,2,3,4 1 Department of Ophthalmology, he New York Eye and Ear Inirmary of Mount Sinai Health System, 310 E. 14th Street, New York, NY 10003, USA 2 Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA 3 Tissue Culture Center, he New York Eye and Ear Inirmary of Mount Sinai Health System, 310 E. 14th Street, New York, NY 10003, USA 4 Department of Pathology, he New York Eye and Ear Inirmary of Mount Sinai Health System, 310 E. 14th Street, New York, NY 10003, USA Correspondence should be addressed to Dan-Ning Hu; hu2095@yahoo.com Received 3 September 2014; Accepted 15 December 2014 Academic Editor: Takashi Saku Copyright © 2015 Richard Rosen et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Hypoxia is the most important stimulus leading to upregulation of VEGF in the retina and this is caused by accumulation of hypoxia-inducible factors-1 (HIF-1) protein. he efects of zeaxanthin, a natural phytochemical, on the VEGF and HIF-1 expression in the primary culture of human retinal pigment epithelial (RPE) cells were studied. An in vitro RPE cell hypoxia model was established by placing cells under 1% oxygen pressure or by adding cobalt chloride (CoCl 2 ) to the culture medium. RPE cells and conditioned media were collected from cultures treated with and without zeaxanthin under normoxic and hypoxic conditions. VEGF and HIF-1 protein and RNA levels were measured by ELISA kits and RT-PCR, respectively. Hypoxia caused a signiicant increase of VEGF expression and accumulation of HIF-1 in RPE cells. Zeaxanthin at 50–150 M signiicantly inhibited the expression of VEGF and accumulation of HIF-1 protein caused by hypoxia but did not afect expression of VEGF and HIF-1 under normoxic conditions. his is the irst report on the efect of zeaxanthin on VEGF and HIF-1 levels in cultured RPE cells and suggests that zeaxanthin may have potential value in the prevention and treatment of various retinal diseases associated with vascular leakage and neovascularization. 1. Introduction Vascular endothelial growth factor (VEGF) is a growth factor that stimulates the proliferation and migration of vascular endothelial cells and increases vascular permeability [1, 2]. VEGF is the most powerful angiogenesis promoter and plays a signiicant role in the pathogenesis of ocular neovascular- ization diseases, such as diabetic retinopathy and exudative type of age-related macular degeneration (AMD) [3–9]. he most important pathophysiological stimulus leading to high levels of VEGF expression in the retina is hypoxia [3, 4, 7, 9]. Hypoxia causes the increase of VEGF by the accumu- lation of a transcription factor, hypoxia-inducible factor-1 (HIF-1), which promotes the production and secretion of VEGF by various cells including retinal pigment epithelial (RPE) cells [10–26]. Hypoxia is closely related to the develop- ment of neovascularization in the eye. Any drug that inhibits this process may have a therapeutic efect on various retinal diseases related to neovascularization. Zeaxanthin, a natural phytochemical, is a carotenoid pigment of the xanthophyll subclass with a chemical formula C 40 H 56 O 2 . Zeaxanthin is present in various tissues and, in particular, is highly concentrated in the central retina (macula) of the eye [27–32]. Various observational and inter- ventional studies have indicated that zeaxanthin might help reduce the risk of age-related macular degeneration (AMD) [33–41]. In vitro studies have demonstrated that zeaxanthin protected RPE cells and various retinal neurons against Hindawi Publishing Corporation BioMed Research International Volume 2015, Article ID 687386, 11 pages http://dx.doi.org/10.1155/2015/687386