SERCA2a overexpression improves muscle function in a canine Duchenne muscular dystrophy model

Area of Science:

• Biomedical Science
• Gene Therapy
• Muscle Physiology

Background:

• Duchenne muscular dystrophy (DMD) involves muscle degeneration due to excessive cytosolic calcium.
• Sarco/endoplasmic reticulum calcium ATPase (SERCA) pumps calcium into the sarcoplasmic reticulum (SR), counteracting overload.
• Previous studies demonstrated AAV-SERCA2a efficacy in a mouse model of DMD.

Purpose of the Study:

• To evaluate the efficacy of AAV-SERCA2a gene therapy in ameliorating muscle disease in a large animal model of DMD (canine).
• To assess the safety of AAV-SERCA2a gene therapy in normal canine muscle.

Main Methods:

• Injection of AAV vector carrying SERCA2a into the extensor carpi ulnaris (ECU) muscles of juvenile affected dogs.
• Analysis of transgene expression, SERCA2a levels, SR calcium uptake, calpain activity, and muscle contractile properties three months post-injection.
• Evaluation of AAV-SERCA2a safety by injecting the vector into ECU muscles of adult normal dogs.

Main Results:

• Widespread transgene expression and significantly increased SERCA2a levels were observed in AAV-injected muscles of affected dogs.
• Treatment improved SR calcium uptake, reduced calpain activity, enhanced contractile kinetics, and increased resistance to eccentric contraction-induced force loss.
• Muscle histology did not show improvement, but AAV-SERCA2a therapy was safe in normal dogs, with strong transgene expression and no adverse effects on muscle histology or function.

Conclusions:

• AAV-SERCA2a gene therapy demonstrates potential for improving muscle performance in a large mammal model of DMD.
• The therapy effectively enhanced key aspects of muscle function and calcium handling.
• Further investigation is warranted to explore its therapeutic potential for DMD patients.