Abstract
Purpose: :
Decorin gene therapy has been shown to prevent angiogenesis in many non-ocular tissues. This study tested the hypothesis that tissue-selective controlled decorin gene delivery into stroma with AAV5 or cationic lipids retards VEGF-induced neovascularization in rabbit cornea in vivo.
Methods: :
New Zealand White rabbits were used. Neovascularization in the cornea was induced by the implantation of a sucralfate-hydron pellet containing 650ng of vascular endothelial growth factor (VEGF) using micro-pocket assay. Decorin gene was delivered in the rabbit stroma via topical application of 25µl AAV5 (5x10e9 vg/µl) or 50µl transfection sol (50µg DNA mixed with 50nM of DDAB+DOPE lipids). The health of the cornea was monitored with visual eye exam, slit-lamp microscopy and optical coherence tomography. Differential change in corneal neovascularization was measured with steremicropsope, immunocytochemistry, western blotting and real-time PCR techniques. The NIH Image J 1.38X and Adobe Photoshop software were used to quantify vasculature.
Results: :
AAV5 or plasmid-mediated targeted decorin gene delivery in the stroma showed remarkable decrease in blood vessel area, length, and diameter compared to the control corneas in a time-dependent manner from day-3 to day-14. Analysis of stereo- and slit-lamp microscopy data detected substantial reduction in corneal neovascularization (9.8-37.3%) in rabbit eye in vivo with decorin gene therapy. The highest decrease in corneal neovascularization was noted on day-10 (up to 37.3%). Furthermore, decorin-overexpressing rabbit corneas showed delayed appearance of blood vessels, sizable shortening, thinning and retarded migration of blood vessels towards clear cornea compared to control corneas. Preliminary lectin, CD31 and type IV collagen immunochemistry, western blotting and real-time PCR data support these observations. Slit-lamp examination did not detect any clinically significant inflammation, opacity or redness in decorin-delivered or control corneas. The results of optical coherence tomography experiments are still pending.
Conclusions: :
Decorin gene therapy effectively reduces corneal neovascularization in vivo. Studies are underway to define safety, toxicity and doses of tested vectors.
Keywords: gene transfer/gene therapy • cornea: stroma and keratocytes • cornea: basic science