Abstract
Purpose: :
Although corneal transplantation is one of the most successful organ transplants in humans, a significant number donor corneas reject every year; neovascularization within the transplant is an important risk factor. We evaluated the success in preventing neovascularization and rejection in a rabbit model when corneal donor tissue is pretreated with an EIAV lentiviral vector that mediates the expression of angiostatic proteins (EncorStat®).
Methods: :
Equine Infectious Anaemia Virus (EIAV) vectors harboring the angiostatic genes endostatin XVIII and either angiostatin (EncorStat®) or angiostatin kringle-5 (EIAV-Endo:K5) were evaluated. Eighteen New Zealand White rabbits underwent allogenic penetrating keratoplasty in one eye. Corneas were transplanted after overnight incubation with either EncorStat®, EIAV-Endo:K5 or media alone. The area of neovascularizasion from the limbus into the graft was measured by corneal fluorescein angiography, digital photo image assessment and the presence and persistence of opacification was assessed by slit-lamp microscopy. At sacrifice (day 35) the cornea was fixed for histological analysis to assess neovascularization, inflammation, and rejection. Aqueous fluid, vitreous and serum were also collected to determine endostatin and angiostatin levels by ELISA.
Results: :
Corneal rejection was significantly delayed and neovascularization was significantly inhibited by EncorStat® and EIAV- Endo:K5 compared to control group (day 9 onwards, p = 0.009 or less). All corneas in the control group showed new blood vessel formation, severe opacification, dense neovascularization and immune infiltrates, whereas all the EncorStat®-treated group exhibited minimal neovascularization and generally presented with ≤ 1 opacification at each time point studied. Higher levels of angiostatin were observed in aqueous of treated eyes compared with controls.
Conclusions: :
: Presurgical treatment of donor corneas with either angiostatic vector, EncorStat® or EIAV-Endo-K5, was associated with a significant reduction of neovascularization and improved clarity. These vectors may be useful to prevent graft neovascularization and rejection in high-risk human corneal transplant cases.
Keywords: neovascularization • gene transfer/gene therapy • anterior segment