Plasmid-Mediated Gene Therapy in Mouse Models of Limb Girdle Muscular Dystrophy

Abstract

We delivered plasmid DNA encoding therapeutic genes to the muscles of mouse models of limb girdle muscular dystrophy (LGMD) 2A, 2B, and 2D, deficient in calpain3, dysferlin, and alpha-sarcoglycan, respectively. We also delivered the human follistatin gene, which has the potential to increase therapeutic benefit. After intramuscular injection of DNA, electroporation was applied to enhance delivery to muscle fibers. When plasmids encoding the human calpain3 or dysferlin cDNA sequences were injected into quadriceps muscles of LGMD2A and LGMD2B mouse models, respectively, in 3-month studies, robust levels of calpain3 and dysferlin proteins were detected. We observed a statistically significant decrease in Evans blue dye penetration in LGMD2B mouse muscles after delivery of the dysferlin gene, consistent with repair of the muscle membrane defect in these mice. The therapeutic value of delivery of the genes for alpha-sarcoglycan and follistatin was documented by significant drops in Evans blue dye penetration in gastrocnemius muscles of LGMD2D mice. These results indicated for the first time that a combined gene therapy involving both alpha-sarcoglycan and follistatin would be valuable for LGMD2D patients. We suggest that this non-viral gene delivery method should be explored for its translational potential in patients. Keywords: electroporation, alpha-sarcoglycan, calpain3, dysferlin, limb girdle muscular dystrophy, non-viral gene therapy, plasmid DNA, follistatin