Hydrodynamics-based transfection in animals by systemic administration of plasmid DNA

Development of methods that allow an efficient expression of exogenous gene s in animals would provide tools for gene function studies, treatment of di seases and for obtaining gene products. Therefore, we have developed a hydr odynamics-based procedure for expressing transgenes in mice by systemic adm inistration of plasmid DNA. Using cDNA of luciferase and beta-galactosidase as a reporter gene, we demonstrated that an efficient gene transfer and ex pression can be achieved by a rapid injection of a large volume of DMA solu tion into animals via the fail vein. Among the organs expressing the transg ene, the liver showed the highest level of gene expression. AS high as 45 m u g of luciferase protein per gram of liver can be achieved by a single tai l vein injection of 5 mu g of plasmid DNA into a mouse. Histochemical analy sis using beta-galactosidase gene as a reporter reveals that approximately 40% of hepatocytes express the transgene. The time-response curve shows tha t the level of transgene expression in the liver reaches the peak level in approximately 8 h after injection and decreases thereafter. The peak level of gene expression can be regained by repeated injection of plasmid DNA. Th ese results suggest that a simple, convenient and efficient method has been developed and which can be used as an effective means for studying gene fu nction, gene regulation and molecular pathophysiology through gene-transfer , as well as for expressing proteins in animals.