A novel gene therapy to the graft organ by a rapid injection of naked DNA I: Long-lasting gene expression a rat model of limb transplantation

Background. It is important to develop a nontoxic gene transfer method for immunosuppressed patients. In this study, the authors applied a nonviral gene transfer method using rapid injection of naked DNA into the graft limb in rats. Methods. Naked DNA (beta-galactosidase, luciferase, or green fluorescent protein expressing plasmid) was used to test an intravascular gene transfer approach in various conditions on the Lewis rat limb. Then, in a rat limb transplantation model, these marker genes were administered preoperatively (day -2) or perioperatively (day 0) to the graft limb by the authors' "venous protocol." The expression level of luciferase was observed over a long period using a noninvasive living image acquisition IVIS system. Results. Effective intravascular delivery of gene to the rat limb was achieved by a rapid bolus injection of naked DNA through the femoral caudal epigastric vein. Using this procedure, the limb graft with the marker gene perioperatively in place was safely transplanted. After limb transplantation, sustained marker gene expression was observed for more than 2 months. Conclusions. This is the first report showing that the method of rapid injection of naked DNA into the limb can be applied to gene modification for organ transplantation.