Dogs with muscular dystrophy were able to function normally after scientists treated them with an experimental gene therapy, a new study shows.
Researchers at the National Institute of Arthritis and Musculoskeletal and Skin Diseases tested the method using golden retrievers that scientists bred to have Duchenne muscular dystrophy, the most common childhood form of MD.
The research was directed by Dr. Richard Bartlett of the NIAMS and was published in this week's issue of Nature Biotechnology.
The gene that is mutated in MD patients is so large that it makes gene therapy difficult. To get a gene into the human body, scientists often use a vector, or carrier such as an altered virus, to deliver the healthy gene. The larger the gene, the more difficult it is to send into the body, and the more likely it is to cause an adverse immune response.
The NIAMS researchers used a gene therapy technique called gene repair. Instead of replacing an entire faulty gene with a healthy one, researchers created a small molecule called an oligomer, which is identical to the section of the gene containing the mutation, and corrected only the error.
Muscular dystrophy is a disease caused by a gene defect that results in the wasting away of muscle tissue.
Duchenne MD is caused by a defect in the gene that codes for dystrophin, a protein that attaches to other proteins in muscle cells and helps anchor them to connective tissues. The genetic mutation causes the dystrophin protein to die prematurely.
Bartlett and his colleagues created an oligomer that was able to activate repair enzymes and incorporate a corrected gene sequence into the dog model.
The experiment succeeded in restoring the normal function of the dystrophin protein.
Much work has been done on treating the mouse model for MD using direct injection of DNA, delivering gene therapy via viral vectors, and transplantation of muscle cells, but researchers have seen only modest, short-term results.
Researchers say the latest results are impressive, but note that the technique has a long way to go before it can be used in humans.
