Therapeutic Effects of a Novel HIF-1 Inhibitor CLT003 on Diabetic Macular Edema

Abstract

Purpose: : To develop CLT-003, a small molecule inhibitor of HIF-1, for the treatment of diabetic macular edema (DME).

Methods: : CLT003 nanoparticles (CLT003-NPs) were formulated using a water-in-oil-emulsion solvent evaporation method. In vitro assays were used to determine the viability, migration and tube formation of endothelial cells. Chicken chorioallantoic membrane assaywas used to quantify in vivo blood vessel formation. The expression level of angiogenic and inflammatory factors were detected by immuno-labeling, ELISA and Western blotting. CLT-003 and CLT003-NPs were administered by intravitreal injection. The effect of CLT-003 on retinal vascular leakage was evaluated in the animal models of oxygen induced retinopathy (OIR) and streptozotocin (STZ)-induced diabetes and AMD. Retinal vascular leakage was measured using the FITC-albumin or Evans blue extravasation method. Histopathology was observed under microscope.

Results: : In vitro assays demonstrated that CLT003 potently inhibited the growth, migration, and tube formation of endothelial cells. CLT003 also suppressed in vivo blood vessel formation, attenuated the activation of HIF-1 and down-regulated the expression of VEGF and proinflammtion factor ICAM-1. CLT003 reduced retinal vascular leakage in the rat models of OIR and STZ-diabetes. CLT003-NPs potently have sustained effects on the inhibitory growth of endothelial cells. A single intravitreal injection of CLT003-NPs has displayed prolonged efficacy on reduction of retinal vascular leakage for at least 6 weeks in STZ-diabetic rats. Histological analysis did not detect any ocular and systemic toxicity of CLT003 and CLT003-NPs, even at doses much higher than that for therapeutic efficacy.

Conclusions: : CLT003 is a novel HIF-1 inhibitor with therapeutic potential to treat retinal vascular leakage in DME. The nanoparticle-mediated CLT003 delivery can produce sustained reduction of retinal vascular leakage.

Keywords: diabetic retinopathy • drug toxicity/drug effects • hypoxia