Intravitreal Injection of Novel Combretastatin Analog MV-5-40

Abstract

Abstract: : Purpose: To evaluate the ocular toxicity of intravitreally administered combretastatin analog MV-5-40, a potent angiogenic inhibitor. Methods: Twenty-four New Zealand albino rabbits were divided into 6 groups of 4 animals. The animals were anesthetized and treated according to the ARVO resolution. Three animals in each group underwent intravitreal injection of combretastatin (in one eye only) in these concentrations: Group 1, 10 ^–5M; Group 2, 10 ^-6M; Group 3, 10 ^-7M; Group 4, 10^-8M; Group 5, 10 ^–4M; and Group 6, 10 ^-3M. Controls (1 animal per group) were injected intravitreally with 0.17 ml of sterile water. All injections were made through the pars plana using a 25-gauge needle positioned behind the lens. An anterior chamber paracentesis was performed to reduce the intraocular pressure. All animals were examined before and after injection with indirect ophthalmoscopy and slit-lamp biomicroscopy. Baseline and postinjection electroretinography was performed. After 14 days’ follow up, the animals were euthanized and the eyes were enucleated. The eyes were fixed in 2% paraformaldehyde, 3% glutaraldehyde for 48 hours; the globes were cut and placed in phosphate buffer solution. Various concentrations of ethanol were used for tissue dehydration. For pre-infiltration, ethanol and Technovit 7100 were used and the eyes were infiltrated overnight using Technovit 7100. The tissue was embedded in methacrylate overnight and cut at 3 µm, then stained with 1% Toluidine blue. Results: Groups 5 and 6 (10^-4M and 10^-3M) developed cataract, vitreous reaction, and retinal necrosis; the retinal necrosis was more intense in Group 6. Electroretinography showed decreasing b-wave amplitude in Groups 5 and 6; the results were normal in the other groups. Histological examination showed areas of retinal necrosis and disorganization in Groups 5 and 6; Groups 1-4 demonstrated normal-appearing retina. Conclusions: Combretastatin analog MV-5-40 injected intravitreally appeared safe at dosages of 10^-5M or less. All ocular structures were normal in eyes injected with a concentration of 10^-5 M of combretastatin or less.

Keywords: choroid: neovascularization • retinal neovascularization