Abstract
Age-related macular degeneration (AMD) is the major cause of blindness for people over 60. In the "wet" form of AMD compounds targeting growth factor signaling pathways such as VEGF have been a major focus for therapeutic interventions. In a previously developed rat model of CNV, we utilized two receptor tyrosine kinase inhibitors (RTKi) to block VEGFR-1, VEGFR-2 and PDGFR signaling following the establishment of CNV. AAV-VEGF(165) was injected into the subretinal space of rats at postnatal days 15-17. Six weeks later, a suspension of RTK inhibitors, AG013764 or AG013711, was injected intraperitoneally (IP, twice daily) or intravitreally (every five days) over a two week period. FITC-dextran whole-mounts of RPE-choroid-sclera were prepared after the animals were sacrificed. CNV area was quantified using Neurolucida to measure the hyperfluorescence on FITC-dextran whole-mounts. Histology and immunohistochemistry were performed as described previously. VEGF expression in control and treated eyes was confirmed by immunohistochemistry and histological sections indicated recovery of retinal morphology and CNV reduction in treated eyes. In the animals IP injected with AG013764 or AG013711 the mean CNV level was reduced by 25 to 33% compared to control, but this effect did not achieve statistical significance. Intravitreal injections of AG013764 or AG013711 reduced the level of CNV by approximately 60% compared to control (p<0.005 or p<0.05, respectively). These data show that two RTK inhibitors, AG013764 or AG013711, delivered intravitreally, significantly reduce blood vessel proliferation in this AAV-VEGF(165) model of CNV.