A drug-tunable Flt23k gene therapy for controlled intervention in retinal neovascularization

AbstractGene therapies that chronically suppress vascular endothelial growth factor (VEGF) represent a new approach for managing retinal vascular leakage and neovascularization. However, constitutive suppression of VEGF in the eye may have deleterious side effects. Here, we developed a novel strategy to introduce Flt23k, a decoy receptor that binds intracellular VEGF, fused to the destabilizing domain (DD) ofEscherichia coli dihydrofolate reductase (DHFR) into the retina. The expressed DHFR(DD)-Flt23k fusion protein is degraded unless “switched on” by administering a stabilizer; in this case, the antibiotic trimethoprim (TMP). Cells transfected with the DHFR(DD)-Flt23k construct expressed the fusion protein at levels correlated with the TMP dose. Stabilization of the DHFR(DD)-Flt23k fusion protein by TMP was able to inhibit i ntracellular VEGF in hypoxic cells. Intravitreal injection of self-complementary adeno-associated viral vector (scAAV)-DHFR(DD)-Flt23k and subsequent administration of TMP resulted in tunable suppression of ischemia-induced retinal neovascularization in a rat model of oxygen-induced retinopathy (OIR ). Hence, our study suggests a promising novel approach for the treatment of retinal neovascularization.Graphic abstractSchematic diagram of the tunable system utilizing the DHFR(DD)-Flt23k approach to reduce VEGF secretion.a The schematic shows normal VEGF secretion.b Without the ligand TMP, the DHFR(DD)-Flt23k protein is destabilized and degraded by the...
Source: Angiogenesis - Category: Molecular Biology Source Type: research