Abstract
Purpose:
Neovascular retinopathies collectively comprise the most common cause of blindness and affect millions of people from infants to the elderly. Our previous study has demonstrated that a novel deca-peptide, TKII-10, effectively inhibits angiogenesis in chick chorioallantoic membrane and corneal neovascularization. The purpose of this study is to investigate the inhibitory efficacy and mechanism of TKII-10 on retinal neovascularization, in an effort to develop a small peptide for clinical application in neovascular retinopathies.
Methods:
(1) In vitro, MTS asssy, cell migration assay with tranwell chamber, and tube formation assay on Matrigel were carried out to evaluate the inhibitory effect of TKII-10 on VEGF induced retinal endothelial cell proliferation, migration, and tube formation. Bevacizumab (Avastin) was set as positive control, and a scramble peptide, TKII-10S, was set as negative control. (2) The antiangiogenic effect of TKII-10 was further confirmed in retinal neovascularization in oxygen-induced retinopathy in vivo. (3) In oxygen-induced retinopathy model, real time PCR and western blot assays were used to explore the influence of TKII-10 on the mRNA and protein expression of VEGF and PEDF in mouse retina.
Results:
(1) TKII-10 inhibited VEGF-induced endothelial cell migration and tube formation dose-dependently. TKII-10 did no inhibit endothelial VEGF-induced cell proliferation. (2) In OIR assay, the TKII-10 group demonstrated obviously reduced nonperfused area, less neovascular tuft at the junction, and improved vessel dilation compared with the PBS group. There was a significant reduction in the number of vascular cell nuclei extending from the retinal surface into the vitreous in TKII-10 group compared with the PBS group (p<0.01). (3) In oxygen-induced retinopathy, intravitreous injection of TKII-10 resulted in down-regulation of VEGF mRNA and protein expression, concomitant up-regulation of PEDF mRNA and protein expression in the oxygen plus TKII-10 group compared with the oxygen plus PBS group (p<0.01).
Conclusions:
TKII-10 potently inhibits VEGF-induced endothelial cell migration and tube formation in vitro while it is inactive in inhibiting endothelial cell proliferation. TKII-10 effectively inhibits pathological retinal neovascularization by down-regulation of VEGF mRNA and protein expression and concominent up-regulation of PEDF mRNA and protein.
Keywords: 700 retinal neovascularization