To investigate the protective effect of a blue-light filtering intraocular lens (yellow IOL) (YA60BB, Hoya) and an ultraviolet (UV)-absorbing IOL (VA60BB, Hoya) on light-induced phototoxicity to retinal pigment epithelial (RPE) cells laden with the lipofuscin fluorophore A2E and on the production of vascular endothelial growth factor (VEGF) after light exposure.University of Tokyo, Tokyo, Japan.The A2E-laden ARPE-19 cells were exposed to white light and a UV-absorbing IOL or a blue-light filtering IOL was placed over the light beam. After 48 hours of irradiation, the viability of the cells was determined with WST-1 (a sodium salt of 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate) assay, and the secreted protein level of VEGF was determined by enzyme-linked immunosorbent assay.Without an IOL, the white-light exposure decreased cell viability to 28% of the nonirradiated control. Although the UV-absorbing IOL tended to reduce light-induced cell death, the decrease was not significant. However, the presence of the blue-light filtering IOL significantly attenuated light-induced cell damage, increasing cell viability to 42%. The secreted VEGF protein level increased 3.2-fold after the A2E-laden RPE cells were exposed to white light. In the presence of the UV-absorbing IOL, the VEGF protein level decreased, but not significantly. The presence of the blue-light filtering IOL significantly attenuated the upregulated VEGF expression compared to upregulation without an IOL.This study supports the theory that a blue-light filtering IOL may be more protective against A2E-induced photochemical damage and inhibit more light-induced VEGF production than a conventional UV-absorbing IOL.
The efficacy of gene therapy using nonviral vector based on polyplex micelle has been studied against corneal neovascularization in mice.A block copolymer, poly(ethylene glycol) (PEG)-block-polycation carrying ethylenediamine units in the side chain (PEG-b-P[Asp(DET)]), was prepared. PEG-b-P[Asp(DET)] formed a polyplex micelle through the polyion complex formation with plasmid DNA. To evaluate in vivo gene transfer efficiency, PEG-b-P[Asp(DET)] micelle was injected into the subconjunctival space of mice, and the expression of the reporter gene was assessed. Furthermore, mouse corneal neovascularization models were treated with the PEG-b-P[Asp(DET)] polyplex micelle containing expression plasmid vector of soluble vascular endothelial growth factor receptor 1 (sflt-1).Subconjunctival injection of the PEG-b-P[Asp(DET)] polyplex micelle containing a reporter gene showed prolonged gene expression with low cytotoxicity. Also, gene transfer into subconjunctival space by the polyplex micelle containing sflt-1 plasmid showed significant inhibition of corneal neovascularization in mice.Nonviral gene therapy using PEG-b-P[Asp(DET)] polyplex micelle may have potential for safe and effective therapeutic treatment of corneal neovascularization.
Purpose: To select a novel orally administered VEGFR-2 (KDR/flk-1) specific tyrosine kinase inhibitor in a murine model of choroidal neovascularization (CNV). Methods: From a compound library, potent VEGFR2 inhibitors were selected by VEGF-induced phosphorylation of VEGFR-2 and RAF kinases and the proliferation analysis by HUVEC cultures and in vitro tube formation assay. CNV was induced in C57/BL6 mice using diode laser photocoagulation. The antiangiogenic effect of selected compounds was assessed by angiographic examination, in which extent of fluorescein leakage was scored and histological analysis, allowing for measurement of CNV membrane under light microscope. In addition, C57/BL6 mice were treated with daily oral administration of selected compounds for 14 days and body weights were measured. Results: Six compounds that potently inhibited VEGFR-2 were selected for further investigation. Selected compounds-treated conditions showed a dose-dependent inhibition of phosphorylation of VEGFR-2 tyrosine kinase with an IC50 of 0.0022 to 0.098 μm. Selected compounds did not inhibit the HCT116 proliferation but did demonstrate a strong inhibition effect for VEGFR-2 dependant HUVEC (IC50 = 0.0018 to 0.058 μm). Selected compounds treatment also resulted in a dose-dependent attenuation of in vitro tube formation. In the murine CNV model, #0451 is the most effective compound. The intensity of fluorescein leakage was significantly lower in doses of 12.5, 25, 50, and 100 mg/kg #0451-treated eyes compared to controls. Histologically, CNV membrane volumes were significantly reduced in #0451-treated eyes in a dose-dependent manner. At therapeutic doses of 100 mg/kg or less, there was no significant weight loss between the treated and untreated groups. Conclusion: Oral administration of #0451, a novel VEGFR-2 (KDR/flk-1)-specific tyrosine kinase inhibitor, demonstrates anti-angiogenic effects in our murine model of CNV. #0451 may be useful to treat the choroidal neovascularization associated with AMD.
A recent study in vitro demonstrated that a major lipofuscin component, A2E, serves as a retinoic acid receptor ligand. The current study investigated the effects of A2E on retinal pigment epithelial (RPE) cells in vivo and was performed to extend the understanding of the effects of A2E. Firstly, subretinal injection of A2E was performed and 3 weeks after the injection, and it was demonstrated that subretinal injection of A2E induced RPE cell death, and concomitant upregulation of vascular endothelial growth factor (VEGF) in the RPE and choroid. The upregulation of VEGF was attenuated by an RARalpha antagonist. Next we performed laser photocoagulation in mice that accumulated A2E either after subretinal injection, by Ccl2 gene knockout or by aging demonstrated that mice that accumulated A2E in the RPE, which showed higher rates of choroidal neobascularization (CNV) formation after weak laser injury than the controls and the formation of CNV was inhibited by an RARalpha antagonist in all models tested. The data suggest that A2E accumulation induces RPE cell death, and concomitant increase of VEGF. Accumulation of A2E alone is not sufficient to induce CNV in vivo, but induces the expression of VEGF in RPE and choroid. The mice that accumulated A2E in RPE cells are vulnerable to CNV development via RAR activation, at least in part.
