title: The use of CpG-free plasmids to mediate persistent gene expression following repeated aerosol delivery of pDNA/PEI complexes.
abstract: Aerosol gene therapy offers great potential for treating acquired and inherited lung diseases. For treatment of chronic lung diseases such as cystic fibrosis, asthma and emphysema, non-viral gene therapy will likely require repeated administration to maintain transgene expression in slowly dividing, or terminally differentiated, lung epithelial cells. When complexed with plasmid DNA (pDNA), the synthetic polymer, 25 kDa branched Polyethylenimine (PEI), can be formulated for aerosol delivery to the lungs. We show that pDNA/PEI aerosol formulations can be repeatedly administered to airways of mice on at least 10 occasions with no detectable toxicity. Interestingly, peak reporter gene activity upon repeated delivery was significantly reduced by up to 75% compared with a single administration, despite similar pDNA lung deposition at each subsequent aerosol exposure. Although the precise mechanism of inhibition is unknown, it is independent of mouse strain, does not involve an immune response, and is mediated by PEI. Importantly, using a dosing interval of 56 days, delivery of a fourth-generation, CpG-free plasmid generated high-level, sustained transgene expression, which was further boosted at subsequent administrations. Together these data indicate that pDNA/PEI aerosol formulations offer a versatile platform for gene delivery to the lung resulting in sustained transgene expression suitable for treatment of chronic lung diseases.
authors.affiliation: Gene Medicine Research Group, Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, University of Oxford, Oxford, UK.
authors.forename: Lee A
authors.initials: LA
authors.lastname: Davies
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Hyde
authors.forename: Graciela
authors.initials: G
authors.lastname: Nunez-Alonso
authors.forename: Reto P
authors.initials: RP
authors.lastname: Bazzani
authors.forename: Rebekka
authors.initials: R
authors.lastname: Harding-Smith
authors.forename: Ian A
authors.initials: IA
authors.lastname: Pringle
authors.forename: Anna E
authors.initials: AE
authors.lastname: Lawton
authors.forename: Syahril
authors.initials: S
authors.lastname: Abdullah
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Roberts
authors.forename: Dominique
authors.initials: D
authors.lastname: McCormick
authors.forename: Stephanie G
authors.initials: SG
authors.lastname: Sumner-Jones
authors.forename: Deborah R
authors.initials: DR
authors.lastname: Gill
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols / Q000008:administration & dosage; D000818:Animals; D018899:CpG Islands / Q000235:genetics*; D004337:Drug Carriers / Q000737:chemistry*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics*; D007097:Imines / Q000737:chemistry*; D008168:Lung / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010957:Plasmids / Q000008:administration & dosage* / Q000235:genetics*; D011095:Polyethylenes / Q000737:chemistry*; D014018:Tissue Distribution
chemical_list: D000336:Aerosols; D004337:Drug Carriers; D007097:Imines; D011095:Polyethylenes; C505405:poly(ethylene imine)