Intranasal Delivery of Compacted Plasmid-DNA Nanoparticles Achieves Transfection and Expression in Rat Brain

Abstract

Glial cell line-derived neurotrophic factor (GDNF) has potential as treatment for various CNS disorders. However, GDNF gene therapy has been limited to direct intracranial injection of viral vectors, posing a safety risk due to immunogenicity of the vector and invasiveness of surgical injection. To circumvent this, we are investigating intranasal administration of non-viral vectors as a non-invasive pathway to the brain. Copernicus Therapeutics, Inc. has developed a non-immunogenic PEGylated polylysine (PEG-CK30) nanoparticle vector that compacts single expression plasmids. We have previously shown that intranasal administration of PEG-CK30 nanoparticles complexed with an enhanced green fluorescent protein (eGFP)-expressing plasmid transfects cells throughout the rat brain. The goal of this study was to assess in vivo transfection by compacted eGFP-GDNF plasmid (pUGG) nanoparticles in which GFP acts as a reporter protein to monitor GDNF expression. We first assessed transfection 7 and 14 days after direct injection of pUGG into rat striatum. Fluorescence microscopy, GFP-immunohistochemistry, and GFP-ELISA all confirmed similar levels of transfection by pUGG along the needle tract at both time-points. In addition, GDNF bioactivity was demonstrated by an increase in tyrosine hydroxylase (TH) staining along the needle tract. Finally, we assessed whether pUGG could achieve transfection in the brain after intranasal delivery. Expression was determined 7 days post-administration by GFP-ELISA. Significant GFP expression was observed primarily in the frontal cortex, but also along the entire rostral-caudal axis of the brain. These results show that intranasal delivery of compacted plasmid-DNA nanoparticles can serve as a viable method of gene therapy for CNS disorders.