Comparison of the Effects of Discodermolide and Mitomycin C on Proliferation of Cultured Human Tenon and Conjunctival Fibroblasts and on Wound Healing After Glaucoma Filtration Surgery in Rabbits

Abstract

Purpose: : Mitomycin C (MMC) is used to reduce postoperative wound fibrosis increasing the success of glaucoma filtration surgery. The use of MMC is associated with an increased risk of postoperative complications. Discodermolide (DC) is a natural compound isolated from the marine sponge, Discodermia dissoluta. DC hyperstabilizes microtubules leading to mitotic arrest. We compared the efficacy of DC and MMC to: 1) inhibit proliferation of cultured human tenon and conjunctival fibroblasts, and 2) prevent fibrosis after filtration surgery in rabbits.

Methods: : Immunofluorescence of microtubules, and the XTT cell proliferation assay were used to investigate the mechanism of action and antiproliferative effects of DC and MMC on cultured human tenon and conjunctival fibroblasts. In a pilot study to examine wound healing, six albino rabbits underwent bilateral posterior lip sclerectomies. The eyes were divided into three groups: (1) MMC (1.2 mM (0.4 mg/ml) applied on a sponge for 3 minutes; n=3); (2) DC10 (0.2 ml of 10 µM DC injected in the subtenon space intraoperatively; n=3); (3) DC100 (0.2 ml of 100 µM DC injected in the subtenon space intraoperatively; n=6). Intraocular pressures and adverse effects were followed for 21 days at which point the animals were sacrificed.

Results: : Immunofluorescence labeling confirmed microtubule bundling in DC-treated cultured tenon and conjunctival fibroblasts (0.1-1.0 µM). Proliferation studies demonstrated that a 48 hr DC exposure inhibited fibroblasts proliferation (EC50= 73.0 nM) with a greater potency than MMC (EC50= 8.68 µM). However, the maximum anti-proliferative effect of DC was smaller compared to MMC. Postoperative intraocular pressures in DC and MMC-treated eyes were not significantly different and there were no adverse effects associated with DC use.

Conclusions: : The results suggest that DC inhibits ocular fibroblast proliferation and may be a safe alternative drug to MMC for fibrosis suppression after trabeculectomy.

Keywords: wound healing