Abstract
Abstract: :
Purpose:The failure of glaucoma filtering surgery (GFS) is generally caused by excessive conjunctival scarring and contraction of the "bleb" site. Previous studies have demonstrated that Transforming Growth Factor–Beta (TGF–ß) and Connective Tissue Growth Factor (CTGF) are important in mediating this process. The purpose of this study was to identify other factors, which may play a role in clinical bleb failure following GFS. Methods:GFS was performed in one eye of 27 adult Sprague–Dawley rats, by creating a limbal–based conjunctival flap, inserting a 30G, cannula through a scleral (needle) tunnel into the anterior chamber and suturing the conjunctiva closed to create a filtering bleb. Nine blebs were harvested at each time point, at days; 2, 5 and 12 days respectively following surgery. All blebs had failed by day 12. For each time point 3 blebs from each treatment were pooled yielding 3 replicates. In a similar manner, conjunctival and Tenons tissue were harvested from 9 further normal (unoperated) rats and pooled to yield 3 control replicates. For each of the pooled samples, total RNA was extracted, labeled and used to hybridize an Affmetrix 230A rat genome microarray. Results:Based on ANOVA results, 1542 genes were differentially expressed (p=0.01). The greatest number of changes in gene expression occurred between day 0 and day 2. Many of these genes had returned to control levels by day 12. The differentially expressed genes were sorted by Gene Ontology number and also placed into GenMapp pathways. Approximately 750 genes had no functional annotation. The most heavily populated molecular function categories included cell adhesion, apoptosis regulators and structural molecules. The most heavily populated pathways included G–protein signaling, cell cycle, apoptosis, glycolysis & gluconeogensis/ TCA cycle and matrix metalloproteinases. Conclusions:To our knowledge this study represents the first large–scale gene expression analysis of GFS bleb failure in a model in which aqueous is shunted to the sub–conjunctival tissues. Studying the functional relations of differentially expressed genes will facilitate the identification of factors which play a significant role in this process may lead to new and specific treatments which prolong bleb survival following GFS.Funded in part by an unrestricted departmental grant from Research to Prevent Blindness