Viral vectors are a commonly used method for gene therapy because of their highly efficient transduction of cells. However, many vectors have a small genetic capacity, and their potential for immunogenicity can limit their usefulness. Moreover, for disorders of the central nervous system (CNS), the need for invasive surgical delivery of viruses to the brain also detracts from their clinical applicability. Here, we show that intranasal delivery of unimolecularly compacted DNA nanoparticles (DNA NPs), which consist of single molecules of plasmid DNA encoding enhanced green fluorescent protein (eGFP) compacted with 10 kDa polyethylene glycol (PEG)-substituted lysine 30-mers (CK30PEG10k), successfully transfect cells in the rat brain. Direct eGFP fluorescence microscopy, eGFP-immunohistochemistry (IHC) and eGFP-ELISA all demonstrated eGFP protein expression 2 days after intranasal delivery. eGFP-positive cells were found throughout the rostral-caudal axis of the brain, most often adjacent to capillary endothelial cells. This localization provides evidence for distribution of the nasally administered DNA NPs via perivascular flow. These results are the first report that intranasal delivery of DNA NPs can bypass the blood-brain barrier and transfect and express the encoded protein in the rat brain, affording a non-invasive approach for gene therapy of CNS disorders.

and Loqus23. All honoraria for these engagements were paid through the offices of UCL Consultants Ltd., a wholly owned subsidiary of University College, London. MRH currently serves on the public boards of Ionis Pharmaceuticals, Xenon Pharmaceuticals, Aurinia Pharmaceuticals and 89bio.

Glial cell line-derived neurotrophic factor (GDNF) gene therapy could offer a disease-modifying treatment for Parkinson's disease (PD). Here, we report that plasmid DNA nanoparticles (NPs) encoding human GDNF administered intranasally to rats induce transgene expression in the brain and protect dopamine neurons in a model of PD. To first test whether intranasal administration could transfect cells in the brain, rats were sacrificed 1 week after intranasal pGDNF NPs or the naked plasmid. GDNF ELISA revealed significant increases in GDNF expression throughout the brain for both treatments. To assess whether expression was sufficient to protect dopamine neurons, naked pGDNF and pGDNF DNA NPs were given intranasally 1 week before a unilateral 6-hydroxydopamine lesion in a rat model of PD. Three to four weeks after the lesion, amphetamine-induced rotational behavior was reduced, and dopaminergic fiber density and cell counts in the lesioned substantia nigra and nerve terminal density in the lesioned striatum were significantly preserved in rats given intranasal pGDNF. The NPs afforded a greater level of neuroprotection than the naked plasmid. These results provide proof-of-principle that intranasal administration of pGDNF DNA NPs can offer a non-invasive, non-viral gene therapy approach for early-stage PD.