Utilizing Targeted Gene Therapy with Nanoparticles Binding Alpha v Beta 3 for Imaging and Treating Choroidal Neovascularization

Purpose: The integrin avb3 is differentially expressed on neovascular endothelial cells. We investigated whether a novel intravenously injectable avb3 integrin-ligand coupled nanoparticle (NP) can target choroidal neovascular membranes (CNV) for imaging and targeted gene therapy. Methods: CNV lesions were induced in rats using laser photocoagulation. The utility of NP for in vivo imaging and gene delivery was evaluated by coupling the NP with a green fluorescing protein plasmid (NP-GFPg). Rhodamine labeling (Rd-NP) was used to localize NP in choroidal flatmounts. Rd-NP-GFPg particles were injected intravenously on weeks 1, 2, or 3. In the treatment arm, rats received NP containing a dominant negative Raf mutant gene (NP-ATP mu-Raf) on days 1, 3, and 5. The change in CNV size and leakage, and TUNEL positive cells were quantified. Results: GFP plasmid expression was seen in vivo up to 3 days after injection of Rd-NP-GFPg. Choroidal flatmounts confirmed the localization of the NP and the expression of GFP plasmid in the CNV. Treating the CNV with NP-ATP mu-Raf decreased the CNV size by 42% (P < 0.001). OCT analysis revealed that the reduction of CNV size started on day 5 and reached statistical significance by day 7. Fluorescein angiography grading showed significantly less leakage in the treated CNV (P < 0.001). There were significantly more apoptotic (TUNEL-positive) nuclei in the treated CNV. Conclusion: Systemic administration of avb3 targeted NP can be used to label the abnormal blood vessels of CNV for imaging. Targeted gene delivery with NP-ATP mu-Raf leads to a reduction in size and leakage of the CNV by induction of apoptosis in the CNV.