The Inhibitory Effect of Connective Tissue Growth Factor Antibody on Postoperative Fibrosis in a Rabbit Model of Trabeculectomy

Abstract

Purpose: To compare the efficacy of subconjunctival injection of an anti-connective tissue growth factor antibody (anti-CTGF) versus mitomycin-C (MMC) and placebo in reducing scar formation in a rabbit model of trabeculectomy. Methods: A total of 14 rabbits were included. Nine rabbits underwent trabeculectomy with subconjunctival injections of either anti-CTGF antibody, MMC, or balanced salt solution (BSS), each administered in three eyes, before peritomy. The anti-CTGF group received a repeated dose of the antibody five days after surgery. All nine rabbits were euthanized on day 14; the globes were stained with hematoxylin & eosin, Masson’s Trichrome, and immunohistochemistry for detecting alpha-smooth muscle (α-SMA) actin. RNA extraction was performed on five eyes of the remaining rabbits which included one eye without any surgery, one eye 5 hr after trabeculectomy without any injection, one eye five days after trabeculectomy without any injection, and two eyes five days after trabeculectomy with administration of MMC and BSS, respectively. Results: The mean bleb area in the anti-CTGF, MMC, and control groups was 3.8 ± 1.45, 5.9 ± 1.4, and 3.5 ± 1.9 mm2, respectively. Collagenous tissue was found to occupy the bleb area by 13.7%, 13.5%, and 18.5%, respectively. This ratio was significantly higher in the BSS group (P = 0.04). The expression of CTGF mRNA after 5 hr and five days in eyes undergoing trabeculectomy were significantly more pronounced as compared to the unoperated eye. The mean H-SCORE of α-SMA-immune reactive cells calculated as the grade of staining multiplied by the percentage of immune stained cells was 14.6, 10.22, and 140.58 in the anti-CTGF, MMC, and control groups, respectively. While the control eyes had a significantly higher score (Ps < 0.001), the anti-CTGF and MMC groups were comparable (P = 0.87). Conclusion: Based on the results of this animal study, the anti-CTGF antibody injection resulted in a significant reduction in collagenous tissue and myofibroblast cells after trabeculectomy.