Abstract
Purpose: :
Glaucoma filtration surgery (GFS) commonly fails due to scarring at the surgical site. Bevacizumab has been shown to enhance bleb survival in rabbit models of glaucoma filtration surgery. However, the mechanisms by which bevacizumab exerts its positive effects are unknown. We therefore used the mouse model of GFS to determine if the effect of this drug can be reproduced in the mouse as well as to analyse the biological changes in the subconjunctiva as a result of bevacizumab application.
Methods: :
Bevacizumab was injected into the subconjunctiva of the mouse eye post-surgery using the mouse model of GFS. Surgery was performed on the left eyes and 5 μl of human IgG (25 mg/ml) or bevacizumab (25 mg/ml) were injected into the subconjunctiva of the operated eye at day 0 and day 2 of surgery. The blebs were imaged by slit lamp microscopy, anterior segment-coherence tomography, and confocal microscopy at day 2, day 7 and thereafter until the blebs could no longer be detected. Bleb survival was evaluated by the Kaplan-Meier survival analysis with log rank significance test (SPSS Statistics 17.0). Blebs at day 2 and day 7 were also harvested to quantify the mRNA expression of a plethora of genes including extracellular matrix (ECM), ECM-modifying, VEGF and cytokine genes. The tissues were pooled together in 3 groups of 5 animals each for quantitative PCR (qPCR) analysis.
Results: :
Bleb survival was significantly improved with bevacizumab application (log rank, P=0.004). qPCR analysis of the bleb tissues indicated that transcripts of MMP-1, MMP-9, TGF-β2, VEGFR-2, COX-2 as well as IL-6 were significantly reduced at day 2 after surgery. The levels of these transcripts were not signficantly different from IgG controls by day 7 post-surgery even though bevacizumab appeared to prolong bleb survival long past day 7. Blebs could be detected at up to day 56 post-surgery with the application of bevacizumab.
Conclusions: :
Our data suggests that bevacizumab is effective in prolonging bleb survival by reducing the expression of critical pro-fibrotic and inflammatory genes in vivo. Moreover, our study indicates that intervening at the earliest stages of the wound healing process post-surgery is sufficient to bring about a long term beneficial effect.
Keywords: wound healing • extracellular matrix • gene/expression