Solid Lipid Nanoparticle Carrier Platform Containing Synthetic TLR4 Agonist Mediates Non-Viral DNA Vaccine Delivery

There is a growing demand for better delivery systems to improve the stability and efficacy of DNA vaccines. Here we report the synthesis of a non-viral DNA vaccine delivery system using a novel adjuvanted solid lipid nanoparticle (SLN-A) platform as a carrier for a DNA vaccine candidate encoding the Urease alpha (UreA) antigen from Helicobacter pylori. Cationic SLN-A particles containing monophosphoryl lipid A (adjuvant) were synthesised by a modified solvent-emulsification method and were investigated for their morphology, zeta potential and in vitro transfection capacity. Particles were found to bind plasmid DNA to form lipoplexes, which were characterised by electron microscopy, dynamic light scattering and fluorescence microscopy. Cellular uptake studies confirmed particle uptake within 3 h, and intracellular localisation within endosomal compartments. In vitro studies further confirmed the ability of SLN-A particles to stimulate expression of pro-inflammatory cytokine tumor necrosis factor alpha (TNF-α) in human macrophage-like Tohoku Hospital Pediatrics-1 (THP-1) cells. Lipoplexes were found to be biocompatible and could be efficiently transfected in murine immune cells for expression of recombinant H. pylori antigen Urease A, demonstrating their potential as a DNA vaccine delivery system.