42. Uniform Scale-Independent Gene Transfer to Striated Muscle after Transvenular Extravasation of Vector

Top of pageAbstract The muscular dystrophies exemplify a class of systemic disorders for which widespread protein replacement in situ is essential for full complementation of the underlying genetic disorder. As a direct approach to this clinical challenge, somatic gene transfer will require efficient, scale-independent transport of DNA-containing macromolecular complexes too large to cross the continuous endothelia under physiological conditions. Previous studies in large animal models have revealed a trade-off between the efficiency of gene transfer and the inherent safety of the required surgical and pharmacological interventions. We tested the hypothesis that rapid, mechanical distention of the post-capillary venular endothelium by afferent infusion from a distal site would safely facilitate macromolecular transport from the vascular space to the striated muscle interstitium. We show that pressurized infusion through a large-bore catheters in either peripheral, superficial veins or the coronary sinus results in uniform, scale-and vector-independent transduction of myofibers in anatomic domains isolated from the remainder of the circulation. This approach is rapid, minimally invasive as applied to the isolated limb, and avoids pharmacological interference with cardiovascular homeostasis. We provide the first demonstration of uniform gene transfer to virtually 100% of the muscle fibers of an entire extremity in the dog, providing a firm foundation for studies of efficacy in canine models for human diseases. Additional data from a combination of angiographic, tracer dye, and marker gene studies suggests that this approach can be modified to meet the requirements for cardiac-specific or systemic gene delivery as appropriate in a variety of inherited and acquired diseases including hemophilia, muscular dystrophy, and cardiomyopathy. Figure 1 |[ndash]| |[beta]|-galactosidase levels of rat limb, rat cardiac and dog limb muscles after no treatment, vector delivery without afferent transvenular retrograde extravasation (ATVRX) and vector delivery with ATVRX. Figure 2 |[ndash]| LacZ expression after rat quadriceps (left), rat heart (middle), and dog vastus medialis (right) stained with x-galactosidase.