Limb girdle muscular dystrophy (LGMD) describes a group of inherited diseases resulting from mutations in genes encoding proteins involved in maintaining skeletal muscle membrane stability. LGMD type-2D is caused by mutations in alpha-sarcoglycan (sgca). Here we describe muscle-specific gene delivery of the human sgca gene into dystrophic muscle using an adeno-associated virus 1 (AAV1) capsid and creatine kinase promoter. Delivery of this construct to adult sgca-/- mice resulted in localization of the sarcoglycan complex to the sarcolemma and a reduction in muscle fiber damage. Sgca expression prevented disease progression as observed in vivo by T2- weighted magnetic resonance imaging (MRI) and confirmed in vitro by decreased Evan's blue dye accumulation. The ability of recombinant AAV-mediated gene delivery to restore normal muscle mechanical properties in sgca-/- mice was verified by in vitro force mechanics on isolated extensor digitorum longus (EDL) muscles, with a decrease in passive resistance to stretch as compared with untreated controls. In summary, AAV/AAV-sgca gene transfer provides long-term muscle protection from LGMD and can be non-invasively evaluated using magnetic resonance imaging.
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We would like to thank the University of Florida Viral Vector Core for making the virus preparations used in these experiments. Also we would like to acknowledge the University of Florida Advanced Magnetic Resonance Imaging and Spectroscopy Facility for their assistance in the MRI described in this work and the Molecular Pathology and Immunology Core for tissue section preparations. This work was supported by grants from the National Institutes of Health (NHLBI PO1 HL59412, NIDDK PO1 DK58327, AT-NHLBI-U01 HL69748, AR47292 and Glenn A. Walter was supported by RO1 HL78670), the Muscular Dystrophy Association, and the American Heart Association (AHA) Florida and Puerto Rico Affiliate (C.A.P.) and the National Center of the AHA (C.S.M.). B.J.B., the Johns Hopkins University, and the University of Florida could be entitled to patent royalties for inventions described in this manuscript.