Design and Optimization of Clinical Gene Gun for Delivery of Nucleic Acid Vaccines

Gene gun delivery of DNA vaccinesalso known as particle mediated epidermal delivery or PMEDdelivers DNA vaccines coated ontomicron sized gold particles directly into cells of the epidermisIt achieves pain free deliveryis considerably more efficient than electroporation or other DNA vaccine delivery approachesrequiresfold lower dosesand induces both systemic and mucosal responsesThe gene gun stands out as the only DNA vaccine technology to date that has consistently induced T cell responses and protective levels of antibody inof vaccinated subjects in human clinical trialsIn additionin preclinical studiesthe research grade gene gun effectively induces mucosal responses that correlate with enhanced protection micenonhuman primates and swine models of influenzaHSV and HIV infectionsHoweverwhen transitioned into the clinicthe immunogenicity of PMED DNA vaccines in humans using a newly designed clinical gene gun resulted in lower immune responses than what was achieved with the research device in preclinical animal modelsOur preliminary studies show that these earlier clinical devices fell short of optimal engineeringIn particularthe first clinical gene guns delivered the particles into a smaller area and fewer particles penetrated the skin when compared to the research deviceThis is likely due to the use of a polystyrene nozzle in the clinical device that generated an electrostatic charge and restricted gold particle accelerationIn additionfor both the research and clinical devicesthe density distribution of the particles fell in a bell curve with the center of the target having a much higher density of particles and lower viability than the outer areaThis decreased viability of the cells in the center of the target caused reduced DNA vaccine expression due to a andquot dead centerandquotAnother obstacle to more robust vaccine expression in the use of DNA coated particles is that DNA must enter the nucleuswhile the majority of delivered particles now reach only the cytoplasm and fall short of the nucleusHerewe propose to address these limitations by incorporating novel engineering modifications to the research and clinical gene gunsaspinnerapparatus that will increase the target size and particle distribution and a hybrid aluminum plastic disposable clinical gene gun barrel to reduce electrostatic restriction of the gold particlesWe will alsoin collaboration with GE Global Researchinvestigate novel nucleic acid formulations for better nuclear localization and vaccine expression by employing a Rolling Circle AmplifiedRCADNA and stable RNA and RNA DNA compositions as strategies to increase the number of cells expressing the gene and the amount of protein expressed per cellWe hypothesize these modifications will result in generation of a newmore effective research and clinical gene guns with enhanced immunogenicity in vivo We propose to engineer two novel modifications into a needle free delivery device or gene gun and optimize RNA and DNA gold particle formulationsWe hypothesize these modifications will increase target sizecell viability and greater gene expression resulting in greater immunogenicity of nucleic acid vaccinesIf successfulthis work could overcome previous limits in DNA vaccine immunogenicity in humans