Recombinant Adeno-Associated Virus Type 8-Mediated Extensive Therapeutic Gene Delivery into Skeletal Muscle ofα-Sarcoglycan-Deficient Mice

Abstract

Autosomal recessive limb-girdle muscular dystrophy type 2D (LGMD 2D) is caused by mutations in the alpha-sarcoglycan gene (alpha-SG). The absence of alpha-SG results in the loss of the SG complex at the sarcolemma and compromises the integrity of the sarcolemma. To establish a method for recombinant adeno-associated virus (rAAV)-mediated alpha-SG gene therapy into alpha-SG-deficient muscle, we constructed rAAV serotypes 2 and 8 expressing the human alpha-SG gene under the control of the ubiquitous cytomegalovirus promoter (rAAV2-alpha-SG and rAAV8-alpha-SG). We compared the transduction profiles and evaluated the therapeutic effects of a single intramuscular injection of rAAVs into alpha-SG-deficient (Sgca(-/-)) mice. Four weeks after rAAV2 injection into the tibialis anterior (TA) muscle of 10-day-old Sgca(-/-) mice, transduction of the alpha-SG gene was localized to a limited area of the TA muscle. On the other hand, rAAV8-mediated alpha-SG expression was widely distributed in the hind limb muscle, and persisted for 7 months without inducing cytotoxic and immunological reactions, with a reversal of the muscle pathology and improvement in the contractile force of the Sgca(-/-) muscle. This extensive rAAV8-mediated alpha-SG transduction in LGMD 2D model animals paves the way for future clinical application.

Systemic delivery of adeno-associated viral vectors

“…Today, impressive results have been reported in neonatal, adult and even aged animals. Some of these examples include AAV-1 mediated gene therapy for Pompe disease, limb-girdle muscular dystrophy (LGMD) and myotonic dystrophy [33-35], AAV-6 mediated gene therapy for DMD and facioscapulohumeral muscular dystrophy [25,36-38], AAV-8-mediated gene therapy for DMD, LGMD and atherosclerosis [26,39-41], and AAV-9 mediated gene therapy for cardiomyopathy, lysosomal storage disorders and neuronal diseases [42-51]. …”

Current Challenges and Future Directions in Recombinant AAV-Mediated Gene Therapy of Duchenne Muscular Dystrophy

“…Furthermore, this protein supplementation therapy by rAAV1-mediated muscle transduction was quite effective to prevent vascular remodeling and end-organ damage in the stroke-prone spontaneously hypertensive rat [50]. Interestingly, α-sarcoglycan expression with single intramuscular injection of rAAV8 was widely distributed in the hind limb muscle as well as cardiac muscle, and persisted for 7 months with a reversal of the muscle pathology and improvement in the contractile force in the alpha-sarcoglycan-deficient mice [34]. Intravenous administration of rAAV8 into the hind limb in dogs resulted in improved transgene expression in the skeletal muscles lasting over a period of eight weeks [51].…”

“…Although recent studies suggest that vectors based on AAV are capable of body-wide transduction in rodents [34], translating the characteristics into large animals with advanced immune system remains a lot of challenges. Intravascular delivery can be performed as a form of limb perfusion, which might bypass the immune activation of DCs in the injected muscle [90].…”

Efficient AAV Vector Production System: Towards Gene Therapy For Duchenne Muscular Dystrophy

“…[20] Interestingly, alpha-sarcoglycan expression with single intramuscular injection of rAAV8 was widely distributed in the hind limb muscle as well as cardiac muscle, and persisted for 7 months with a reversal of the muscle pathology and improvement in the contractile force in the alpha-sarcoglycan-deficient mice. [21] Intravenous administration of rAAV8 into the hind limb in dogs resulted in improved transgene expression in the skeletal muscles lasting over a period of 8 weeks. [22] Moreover, rAAV9 would be administered systemically with excellent cardiac tropism.…”