Development of Magnetic Force-Assisted New Gene Transfer System Using Biopolymer-Coated Ferromagnetic Nanoparticles

Development of a simple method for converting the lipid envelope of an inactivated virus to a gene transfer vector was achieved a couple years ago in the medical school of Osaka University. Hemagglutinating virus of Japan (HVJ; Sendai virus) envelope (HVJ-E) vector was constructed by incorporating plasmid DNA into inactivated HVJ particles. This HVJ envelope vector introduced plasmid DNA efficiently and rapidly into various cell lines, including cancer cells and several types of primary cell culture. In the present study, efficiency of gene transfer was found to be greatly enhanced by application of a magnetic field. Therefore, we developed a new type of magnet for magnetically enhancing and targeting gene transfection system by using vectors associated with ferromagnetic particles coated with positively/negatively charged biopolymers, which can help to enhance and target gene delivery with higher efficiency. For the transfection experiment in vitro, the HVJ-E vector was mixed with ferromagnetic particles coated with biopolymer and this mixture was added to cultured cells which were set up under the permanent magnet. The effect of the dose of the ferromagnetic particles on the transfection efficiency was discussed. In order to clarify the effect of magnetic field gradient on the accumulation possibility of the magnetic particles and the accuracy of the targeted site in the blood vessels, calculation of the applied magnetic force for the ferromagnetic particles inside the blood vessel was also performed.