Angiogenesis according to Expressive Change of Angiogenic Related Factor in Human RPE under Oxidative Stress

ABSTRACT

PURPOSE: To elucidate the mechanism of neoangiogenesis in human retinal pigment epithelium under oxidative stress. METHODS: Paraquat was added to cultured human retinal pigment epithelium (HRPE) for 72 hours to induce oxidative stress milieu. Expression and production of angiogenic factors, including vascular endothelial growth factor (VEGF) and pigment epithelial derived factor (PEDF), was checked by RT-PCR and Western blot, respectively. The induction of neoangiogenesis was monitored by both tube formation in ECV 304 cell and migration assay of human fetal dermal microvascular endothelial cells. RESULTS: Competitive RT-PCR showed that PEDF gene in paraquat-treated HRPE was expressed at a significantly lower level than in non-treated HRPE. However, Western blot showed a significant increase of VEGF production (p<0.05) and a decrease of PEDF production (p<0.05). Moreover, angiogenesis was dose-dependently increased when the various concentrations of paraquat were added to HRPE. CONCLUSIONS: Taken together, oxidative stress by addition of paraquat caused HRPE to produce more VEGF and less PEDF, thereby leading to neoangiogenesis, and suggesting that the neovascularization in age-related macular degeneration (AMD) is caused by destroying the balance of angiogenic factors in HRPE such as VEGF and PEDF; that is, in oxidative stressed HRPE, more VEGF is released and less PEDF, as compared to normal HRPE.