Inhibition of Choroidal Neovascularization by Intravenous Injection of Adenoviral Vectors Expressing Secretable Endostatin

Abstract

Endostatin is a cleavage product of collagen XVIII that inhibits tumor angiogenesis and growth. Interferon alpha2a blocks tumor angiogenesis and causes regression of hemangiomas, but has no effect on choroidal neovascularization (CNV). Therefore, inhibitors of tumor angiogenesis do not necessarily inhibit ocular neovascularization. In this study, we used an intravenous injection of adenoviral vectors containing a sig-mEndo transgene consisting of murine immunoglobulin kappa-chain leader sequence coupled to sequence coding for murine endostatin to investigate the effect of high serum levels of endostatin on CNV in mice. Mice injected with a construct in which sig-mEndo expression was driven by the Rous sarcoma virus promoter had moderately high serum levels of endostatin and significantly smaller CNV lesions at sites of laser-induced rupture of Bruch's membrane than mice injected with null vector. Mice injected with a construct in which sig-mEndo was driven by the simian cytomegalovirus promoter had approximately 10-fold higher endostatin serum levels and had nearly complete prevention of CNV. There was a strong inverse correlation between endostatin serum level and area of CNV. This study provides proof of principle that gene therapy to increase levels of endostatin can prevent the development of CNV and may provide a new treatment for the leading cause of severe loss of vision in patients with age-related macular degeneration.

EIAV vector-mediated delivery of endostatin or angiostatin inhibits angiogenesis and vascular hyperpermeability in experimental CNV

“…The results using EIAV.endostatin are similar to a previous study using intravenously delivered recombinant adenoviral (rAd) vectors expressing endostatin which resulted in a 53% reduction in CNV area compared with null vector controls. 37 Recombinant adeno-associated vectors (rAAV) delivering endostatin inhibit experimental retinopathy of prematurity. 38 Overexpression of endostatin using rAd and bovine immunodeficiency vectors also inhibits retinal neovascularisation, vasopermeability and retinal detachment in transgenic mice overexpressing VEGF in photoreceptors.…”

Endostatin modulates VEGF-mediated barrier dysfunction in the retinal microvascular endothelium

“…The effects of endostatin on VEGF mediated permeability, and the increase in the levels of expression of occludin by endostatin treatment, may serve to regulate the tight junction at the blood retinal barrier. As a 20 kDa fragment of collagen XVIII, endostatin is a normal component of the basement membranes that surround the vascular tubes and acts as a potent angiogenesis inhibitor in the eye (Mori et al, 2001), possibly acting through a number of cell surface molecules that may serve as endostatin receptors (Dixelius et al, 2002). Endostatin has been shown to affect several endothelial cell functions including migration, survival, proteinase activity and vessel stabilisation (Dixelius et al, 2002).…”

“…This peptide can prevent tumour angiogenesis (O'Reilly et al, 1997) and has also been shown to be efficacious in the eye by preventing retinal and choroidal neovascularisation (Mori et al, 2001, Auricchio et al, 2002and Le Gat et al, 2003. Endostatin may also prevent vasopermeability responses by growth factors and recent studies have suggested that endostatin can reduce VEGF-induced retinal vascular permeability in double transgenic mice with inducible expression of VEGF 165 in the retina (Takahashi et al, 2003).…”

Receptor tyrosine kinase inhibitors AG013764 and AG013711 reduce choroidal neovascularization in rat eye

“…A noteworthy aspect of the present model is that it allows us to generate relatively large areas of CNV (50-100 times the area of a laser-induced CNV; ˜ 0.03 -0.08 mm 2 (Edelman and Castro 2000;Hangai et al, 2001;Mori et al, 2001;Dejneka et al, 2004) ). In the present study, the intervention started six weeks after the initial injection of AAV-VEGF and at least 1-2 weeks after the development of CNV.…”