Hypoxia Regulated Gene Therapy for Neovascularization

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DESCRIPTION (provided by applicant): Our hypothesis is that the hypoxia that elicits neovascularization (NV) forms a mechanistic basis for a novel therapeutic approach to arrest new vessel growth and associated vascular permeability. This approach could radically alter the clinical management of diabetic retinopathy and AMD. The innovative aspects of our proposal are: a) the development of a new gene therapy stategy using recombinant AAV (rAAV) vectors with hypoxia-responsive elements (HRE) to deliver anti-angiogenic molecules exclusively to either RPE cells or Muller cells within the hypoxic regions of retina where new vessels begin to grow, b) the evaluation of whether gene expression in the Muller cells or RPE cells is the more appropriate target for preretinal neovascularization, and which cell type is the more appropriate target for choroidal NV; and c) test a novel idea for laser-activated gene expression for precise delivery to specific pathologies. To accomplish these goals we will: 1 ) Construct AAV-HRE-vectors and characterize their specificity and oxygen response in vitro and in vivo. 2) Using the murine ROP model, identify whether angiostatin, endostatin, or tubedown-1 (a novel regulator of blood vessel growth) offers the best inhibiton in Muller-cell specific vectors (with a GFAP promoter). 3) Using the ROP model, determine whether the inhibition of NV is dependent on the cell location (RPE or Muller cell) in which the therapeutic gene (identified in 2) is expressed. 4) Similarly, using the CNV model, determine whether inhibition of NV is dependent on the cell in which the gene is expressed. (The location of gene expression is controlled by cell-specific promoters.) 5) Since laser treatment upregulates GFAP, we will determine whether it also activates expression of a reporter gene (GFP) in mice treated with Muller-cell specific vectors (GFAP promoters) (rAAV-GFAP-GFP).