DNA-Mediated Gene Therapy in a Mouse Model of Limb Girdle Muscular Dystrophy 2B

Mutations in the gene for dysferlin cause a degenerative disorder of skeletal muscle known as limb girdle muscular dystrophy 2B. To achieve gene delivery of plasmids encoding dysferlin to hind limb muscles of dysferlin knockout mice, we used a vascular injection method that perfused naked plasmid DNA into all major muscle groups of the hind limb. We monitored delivery by luciferase live imaging and western blot, confirming strong dysferlin expression that persisted over the 3-month time course of the experiment. Co-delivery of the follistatin gene, which may promote muscle growth, was monitored by ELISA. Immunohistochemistry documented the presence of dysferlin in muscle fibers in treated limbs, and PCR confirmed the presence of plasmid DNA. Because dysferlin is involved in repair of the sarcolemmal membrane, dysferlin loss leads to fragile sarcolemmal membranes that can be detected by permeability to Evan's blue dye. We showed that after gene therapy with a plasmid encoding both dysferlin and follistatin, statistically significant reduction in Evan's blue dye permeability was present in hamstring muscles. These results suggest that vascular delivery of plasmids carrying these therapeutic genes may lead to simple and effective approaches for improving the clinical condition of limb girdle muscular dystrophy 2B.