Adenovirus-mediated gene therapy using human p21WAF-1/Cip-1 to prevent wound healing in a rabbit model of glaucoma filtration surgery.

OBJECTIVE: To determine if adenovirus-mediated p21(WAF-1/Cip-1) (p21) gene therapy can prevent fibroproliferation and wound healing in a rabbit model of glaucoma filtration surgery. METHODS: In vitro studies were performed using rabbit Tenon fibroblasts harvested from fresh tissue. In vivo studies were conducted in New Zealand white rabbits. A full-thickness sclerotomy was performed under a limbal-based conjunctival flap. Reagents tested included a replication-deficient recombinant adenovirus containing the human p21 gene (rAd.p21); the nonspecific marker gene for green fluorescent protein or beta-galactosidase; mitomycin, 0.5 mg/mL; and balanced saline solution. Each treatment was applied episclerally for 5 minutes before the sclerotomy using a soaked cellulose sponge placed under the surgically created conjunctival flap. Independent experiments were conducted to (1) monitor changes in intraocular pressure during a 30-day period after treatment and examine surgical site histological features, (2) examine changes in bleb morphologic features over 30 days, (3) determine outflow facility 14 days after treatment, and (4) examine the localization and persistence of rAd.p21 expression between 3 and 60 days after treatment. RESULTS: Treatment of Tenon fibroblasts with rAd.p21 resulted in a dose-dependent inhibition of DNA synthesis and cell growth in vitro. In vivo, rAd.p21 inhibited wound healing and fibroproliferation after filtration surgery, comparably to mitomycin. Mitomycin caused notable thinning of the bleb wall. In addition, 2 of the 5 mitomycin-treated eyes exhibited an abscess with hypopyon and hyalitis 30 days after surgery, which was not observed in any of the rAd.p21-treated eyes. None of the treatments resulted in a significantly sustained decrease in intraocular pressure during the 30-day period, although mitomycin treatment resulted in a significant (P =.02) increase in outflow facility 2 weeks after surgery in separate animals. Mitomycin- and rAd.p21-treated eyes had functioning blebs at the end of the experiment based on slitlamp examination. CONCLUSIONS: Mitomycin and rAd.p21 were effective in preventing fibroproliferation and wound healing in a rabbit model of glaucoma surgery. Mitomycin treatment increased outflow facility in normal-pressure eyes. CLINICAL RELEVANCE: Gene therapy with rAd.p21 may provide an effective antiproliferative for glaucoma filtration surgery, without the complications associated with mitomycin.

Matching complementing functions of transformed cells with stable expression of selected viral genes for production of E1-deleted adenovirus vectors.

Production of E1-deleted adenovirus (rAd) vectors requires complementation by E1A and E1B functions provided by the production cell line. The two cell lines most commonly used for production of rAd vectors, 293 and Per.C6, were derived from human primary cells and contain contiguous E1A and E1B sequences from the Ad genome. As an alternative system, we tested complementation of rAd vectors using sequential transfection of individual E1A and E1B expression cassettes into A549 human lung tumor cells, which support highly efficient replication of wild type adenovirus. We found that E1A function could be complemented in A549 cells by the mutant E1Adl01/07, and that E1B function could be provided in such cells using only the 55K E1B gene. Production yields in the resulting producer cell line, designated SL0003, were similar to those obtained from 293 cells without generation of detectable recombinant replication competent adenovirus.