A facile nonviral method for delivering genes and siRNAs to skeletal muscle of mammalian limbs

Delivery is increasingly being recognized as the critical hurdle holding back the tremendous promise of nucleic acid-based therapies that include gene therapy and more recently siRNA-based therapeutics. While numerous candidate genes (and siRNA sequences) with therapeutic potential have been identified, their utility has not yet been realized because of inefficient and/ or unsafe delivery technologies. We now describe an intravascular, nonviral methodology that enables efficient and repeatable delivery of nucleic acids to muscle cells (myofibers) throughout the limb muscles of mammals. The procedure involves the injection of naked plasmid DNA or siRNA into a distal vein of a limb that is transiently isolated by a tourniquet or blood pressure cuff. Nucleic acid delivery to myofibers is facilitated by its rapid injection in sufficient volume to enable extravasation of the nucleic acid solution into muscle tissue. High levels of transgene expression in skeletal muscle were achieved in both small and large animals with minimal toxicity. Evidence of siRNA delivery to limb muscle was also obtained. The simplicity, effectiveness, and safety of the procedure make this methodology well suited to limb muscle gene therapy applications.