Gene delivery via polymeric microneedles : the use of a novel amphipathic peptide

• Main Author: McCaffrey, J.
• Published: Queen's University Belfast 2014
• Subjects: 615.3
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.679228

The focus of this thesis was to develop a two-tier delivery system suitable for DNA delivery in vivo. Firstly, 4 peptides were investigated to determine their ability to overcome the intracellular and extracellular barriers which inhibit the expression of 'naked' DNA when administered in vivo. The RALA peptide was identified as the most efficient DNA delivery vehicle, eliciting greater gene expression in vitro and in vivo following intradermal injection compared to the delivery of 'naked' DNA. The RALA delivery vehicle was also significantly less toxic than the current commercially available gold-standard transfection agent. Subsequently, a microneedle platform for delivery of these RALA/DNA complexes w.as investigated. Three polymer matrices were examinee, PMVE/MA, PVA and PVP and scrutinised for suitability as the structural polymer for the fabrication of the microneedle arrays through analysis of their compatibility with the bioactive RALAIDNA complexes, cellular toxicity and mechanical strength. It was determined that the PVP polymer was the most suitable for microneedle fabrication and as such, research then focused on the determination of the stability of PVP microneedle arrays loaded with RALAIDNA nanoparticles, optimising cargo loading and utilising them in vivo for the delivery of RALAIDNA nanoparticles. The combination of these two technologies proved to be a successful method of eliciting gene expression in vivo. Microneedle administration of RALAIDNA nanoparticles encoding the luciferase protein generated levels of gene expression superior to that observed with the delivery of 'naked' DNA. Moreover, it was proven that the delivery of an antigen-encoding DNA via this method was capable of generating an antigen-specific CD8+ T-cell response. Thus, the nanoparticle/microneedle delivery system developed in this research has the vast potential to revolutionise the field of DNA vaccination.