PITTSBURGH, Nov. 27 Using sophisticated techniques, University of Pittsburgh scientists have engineered perhaps the best gene therapy to date for Duchenne Muscular Dystrophy (DMD), the catastrophic muscle wasting disease that strikes thousands of boys in the United States each year.
The research, conducted in animals and reported in the Nov. 28 issue of the Proceedings of the National Academy of Sciences, is remarkable on several fronts. The Pittsburgh team managed to whittle down the largest gene ever found (14 kilobases) and packaged its most important components (less than 4.2 kilobases) into the smallest and arguably the safest viral vector ever used for gene therapy.
With this work, the investigators demonstrated, for the first time, the minimal amount of the dystrophin gene needed to achieve functional muscle. The gene vector used was a genetically engineered form of adeno-associated virus, or AAV.
When injected into the calf muscles of mice unable to naturally produce the dystrophin protein, the mini-gene construct resulted in the expression of functional dystrophin protein in almost 90 percent of the muscle tissue treated. The dystrophin expression lasted at least one year the duration of the experiments.
Our research showed that we could introduce functional dystrophin into muscle tissue with AAV. This gives us great hope that we can use this gene therapy strategy in a larger animal model of DMD and eventually treat patients within several years, said Xiao Xiao, Ph.D., assistant professor in the department of molecular genetics and biochemistry at the University of Pittsburgh. We were excited to see that mice treated with the mini-dystrophin gene did not show evidence of muscle breakdown many months after treatment, and even after the treated mice exercised, as was seen in untreated mice that lack dystrophin.
With this work, Dr. Xiao and his laboratory have really taken the AAV vector to a new level in its application to the treat
Contact: Lauren Ward
University of Pittsburgh Medical Center