Abstract
Purpose: :
Choroidal neovascularization (CNV) in age-related macular degeneration (AMD) is strongly associated with hypoxia and chronic inflammation. These events typically precede CNV, and are thought to play an underlying role in the induction of the neovascular process. HIF-1 is a transcription factor that is vital in regulating cellular responses to hypoxic and inflammatory conditions. In order to inhibit CNV, we have engineered a viral vector that uses HIF-1 regulation to exploit the pathological conditions in the AMD retina in order to stimulate local production of an angiostatic protein. The purpose of this study was to investigate the effects of a HIF-1 regulated, RPE-specific gene therapy platform in a mouse-model of CNV.
Methods: :
1uL of our HIF-1 regulated, RPE-specific self-complimentary vector (scAAV2-HRSE-HRE-RPE65-hrEndostatin), scAAV2-CMV-Endostatin, or vehicle control was injected subretinally in 6-9 month old C57BL/6 mice. approximately one week post-injection a 532nm diode laser was used to induce CNV (100uM spot size, 150mW power, & 0.1s duration). Three spots per eye were lasered; two weeks post-laser injury the mice were perfused with a FITC-conjugated tomato lectin. The eyes were then enucleated and RPE/Choroid/Sclera flatmounts were made and coverslipped. Confocal microscope images of fluorescent vessels and CNV areas within the lesions were quantified using Image J.
Results: :
CNV area was 80% smaller (P<0.0001) in eyes treated with the HIF-1 regulated, RPE-specific endostatin vector than in the vehicle injected eyes. CNV was also significantly reduced in eyes treated with the CMV-endostatin vector.
Conclusions: :
Although both scAAV2-CMV-Endostatin and scAAV2-HRES-HRE-RPE-Endostatin significantly reduce CNV, it is unknown whether broad and constitutive endostatin expression will have damaging effects within the retina. Our results indicate that a local, regulated expression can effectively inhibit CNV, and offers the further possibility of a prophylactic treatment for neovascular AMD.
Keywords: gene transfer/gene therapy • retina • neovascularization