Gold Nanoparticles as Potential Vectors for Gene Transfer in the Cornea

Abstract

Purpose: : Gold nanoparticles (GNPs) can transport various bimolecules such as plasmid DNA, nucleotides or peptides and are attractive candidates for gene delivery. We evaluated uptake, toxicity and gene delivery efficiency of gold nanoparticles conjugated to polyethyleneimine (PEI-GNP) or gum arabic (GA-AuNP) in normal and neovascularized rabbit corneas, in vivo.

Methods: : New Zealand White rabbits were used. Neovascularization in the cornea was induced by VEGF implanted in the cornea using micropocket assay. PEI-GNP (2-12nm) or GA-AuNP (6-30nm) or transfection solution (PEI-GNP+Plasmid expressing EGFP under control of CMV+chicken beta actin promoter; N/P 180) was topically applied on the naïve or neovascularized corneas using custom-designed cloning cylinder. Fluorescent microscopy, transmission electron microscopy (TEM), neutron activation atomic absorption spectrometry (NAA), silver staining, TUNEL, immunohistochemistry, stereomicroscopy, slit-lamp biomicroscopy techniques were used to evaluate toxicity, GNP uptake and clearance and health of the cornea.

Results: : Both, normal and neovascularized rabbit corneas showed high levels of GNP uptake. PEI-GNP treated corneas showed higher GNP levels compared to the GA-AuNP corneas. Decrease in GNP levels at 72 hours suggests that GNPs do not accumulate in the cornea and are probably getting cleared after unloading the DNA in the cells. TEM studies confirmed the presence of GNPs in cytosol and nucleus. Varied levels of TUNEL+, CD11b+ and F4/80+ cells were detected in the PEI-GNP or GA-AuNP treated corneas at two tested time points. Transfection solution applied corneas showed significant GFP expression in stroma.

Conclusions: : The tested GNPs can be used to deliver genes in the cornea. More studies are required to define GNPs' toxicity profile, in vivo uptake and clearance for the cornea.

Keywords: gene transfer/gene therapy • cornea: stroma and keratocytes • neovascularization