Utilizing targeted gene therapy with nanoparticles binding alpha v beta 3 for imaging and treating choroidal neovascularization

Purpose

The integrin αvβ3 is differentially expressed on neovascularendothelial cells. We investigated whether a novel intravenously injectableαvβ3 integrin-ligand coupled nanoparticle (NP) can target choroidalneovascular membranes (CNV) for imaging and targeted gene therapy.

Methods

CNV lesions were induced in rats using laser photocoagulation. The utility ofNP for in vivo imaging and gene delivery was evaluated bycoupling 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 thetreatment arm, rats received NP containing a dominant negative Raf mutantgene (NP-ATPμ-Raf) on days 1, 3, and 5. The change in CNV size andleakage, and TUNEL positive cells were quantified.

Results

GFP plasmid expression was seen in vivo up to 3 days afterinjection of Rd-NP-GFPg. Choroidal flatmounts confirmed the localization ofthe NP and the expression of GFP plasmid in the CNV. Treating the CNV withNP-ATPμ-Raf decreased the CNV size by 42% (P<0.001). OCTanalysis revealed that the reduction of CNV size started on day 5 andreached statistical significance by day 7. Fluorescein angiography gradingshowed significantly less leakage in the treated CNV (P<0.001). Therewere significantly more apoptotic (TUNEL-positive) nuclei in the treatedCNV.

Conclusion

Systemic administration of αvβ3 targeted NP can be used to label theabnormal blood vessels of CNV for imaging. Targeted gene delivery withNP-ATPμ-Raf leads to a reduction in size and leakage of the CNV byinduction of apoptosis in the CNV.