Gene replacement therapy for muscular dystrophy

Abstract

Disclosed is a method for treating a patient suffering from the disease sarcoglycan-deficient limb-girdle muscular dystrophy by gene replacement therapy. Sarcoglycan gene replacement therapy produces extensive long-term expression of the sarcoglycan species which restores the entire sarcoglycan complex, results in the stable association of alph&agr;-dystroglycan with the sarcolemma, and eliminates the morphological markers of limb-girdle muscular dystrophy. In another aspect, the invention relates to a method for determining a specific defective sarcoglycan species in the tissue of a patient. The method involves culture of muscle cells obtained from the patient, and the independent introduction of expression vectors encoding each of the sarcoglycan species, &agr;, &bgr;, &ggr;, and &dgr;, into the cultured cells with subsequent assaying for restoration of the dystrophin-glycoprotein complex. In another aspect, the invention relates to a mouse, and cells derived therefrom, homozygous for a disrupted &agr;-sarcoglycan gene. The disruption prevents the synthesis of functional &agr;-sarcoglycan in cells of the mouse and results in the mutant mouse having no detectable sarcospan, &bgr;-, &ggr;-, &dgr;-sarcoglycan, and reduced &agr;-dystroglycan in the sarcolemma of skeletal and cardiac muscles, and a reduction of dystrophin in skeletal muscle, when compared to tissue of a mouse lacking a disrupted &agr;-sarcoglycan gene. In another aspect, the invention relates to methods for screening for therapeutic agents useful in the treatment of sarcoglycan-deficient limb-girdle muscular dystrophy. The methods involve administering a candidate therapeutic agent to a mouse, or cells derived therefrom, and assaying for therapeutic effects on the mouse or cells, with the determination of therapeutic effects being a reduction or reversal in disease progression, or a restoration of the dystroglycan complex.