Nanocapsules with HIF-1-alpha Inhibitor for Treatment of Choroidal Neovascularization in a Rat Model

Abstract

Purpose : Choroidal neovascularization (CNV) is a vision-threatening complication of many retinal diseases, including age-related macular degeneration. Currently, the mainstay of CNV treatment is intravitreal delivery of antibodies that bind VEGF. However, there remains a great need for alternative therapies with longer duration and better treatment effect. This study describes the development of nanocapsule-based formulations toward sustained drug delivery of acriflavine (anti-angiogenic agent that inhibits hypoxia inducible factor [HIF]-1-alpha) and assesses its impact on CNV formation in a rat model.

Methods : Polyurethane nanocapsules were synthesized by an interfacial condensation polymerization reaction in a nanoemulsion. Acriflavine was mixed with isophorone diisocyanate in water and then applied in drop-wise fashion to the solution before lyophilization to form drug capsules. Wild type Brown Norway rats were treated with laser photocoagulation to induce CNV. Eyes were injected intravitreally on the same day with 10 ul of either acriflavine nanocapsules (5 ug total dose of acriflavine) or blank nanocapsules as controls. Animals were assessed at 14-days post-injection with fundus photography, fluorescein angiography, and OCT (Figure). Eyes were enucleated for immunohistochemical analysis. CNV formation was compared between eyes treated with acriflavine versus blank nanocapsules.

Results : Synthesis of acriflavine nanocapsules was reliable (Z-average diameter 197+/-39 nm) with a drug loading efficiency of 41 ug acriflavine/mg of nanocapsules. Following intravitreal injection, both nanocapsule formulations were well-tolerated, without signs of clinical inflammation or retinal toxicity. Visible intravitreal aggregates of nanocapsules were seen at 14-days post-injection. Preliminary qualitative analysis demonstrated markedly decreased sizes of CNV in acriflavine nanocapsules relative to fellow eye controls treated with blank nanocapsules (Figure).

Conclusions : Nanocapsule formulations with acriflavine can be reliably manufactured with consistent drug dosing. Acriflavine nanocapsules are well-tolerated after intravitreal injection in an in vivo rat model and shows promise for inhibiting CNV formation. Studies are ongoing to quantify the effect of CNV inhibition at different dosages as well as various time points to evaluate drug duration.