Intramuscular SP1017-formulated DNA electrotransfer enhances transgene expression and distributes hHGF to different rat tissues

Background. The systemic administration of a therapeutic protein is a common approach for the treatment of multiple disorders. Intramuscular (i.m.) injection of plasmids, followed by electroporation, has been shown to facilitate naked DNA gene transfer in skeletal muscle allowing proteins to be produced and secreted at therapeutically relevant levels. Methods. Plasmid DNA, unformulated or formulated with the non-ionic carrier SP1017, was injected at the rat tibialis anterior muscle followed by the application of electric pulses. Follow-up of protein expression was measured. Results. In our study we report that the non-ionic carrier SP1017 significantly increases transgene expression in rat muscle after the i.m. injection of a formulated-pCMVβ plasmid followed by electroporation. Such increased expression was observed after delivering square-wave unipolar electric pulses at two different field strengths: low (110 V/cm) and high (175 V/cm). Moreover, elevated secreted placental alkaline phosphatase (SEAP) plasma levels were achieved with low-voltage (110 V/cm) electroporation. Our results also show that human hepatocyte growth factor (hHGF) can be produced from rat muscle and delivered to blood circulation at a biologically active level after a single i.m. injection of an SP1017-formulated plasmid (pCMV/hHGF) followed by electroporation. Tissue distribution studies mostly identified hHGF in the liver, but it was also found in the kidneys and lungs suggesting that here too the HGF could be of therapeutic benefit. Conclusions. Our results indicate that SP1017 enhances the expression of electrotransferred genes. Such a delivery approach could prove an efficient method for the systemic production of therapeutic proteins. Copyright © 2003 John Wiley & Sons, Ltd.