Gene therapy of Duchenne myodystrophy is safe
The first chimeric virus to be used in gene therapyNanonews Network http://www.nanonewsnet.ru / based on UNC materials:
Clinical trial for muscular dystrophy demonstrates safety of customized gene therapy
During the phase 1 clinical trials of a chimeric virus to deliver a gene of one of the key muscle proteins to the cells of patients with muscular dystrophy, scientists did not find any side effects.
"This study shows that the possibilities of gene therapy are no longer limited to viruses that exist in nature, and the next generation of viral delivery systems for human genes is on the scene," comments R. Jude Samulski, PhD, Professor of Pharmacology at the University of North Carolina at Chapel Hill, senior author of an article published in the journal Molecular Therapy (Bowles et al., Phase 1 Gene Therapy for Duchenne Muscular Dystrophy Using a Translational Optimized AAV Vector).
Gene therapy makes it possible to treat diseases by correcting the defective genes of the patient. In most cases, the gene therapy approach involves the use of natural systems, such as viruses, to infect cells and embed new genes into their genome. And although many relatively harmless viruses are suitable for this purpose, none of them is ideal.
Without relying on nature, Professor Samulski and his colleagues decided to create a virus of "their dreams" in the laboratory. As a basis, they chose the adenoassociated virus, or AAV, a small non–pathogenic virus that most people encounter repeatedly throughout their lives.
A new chimeric viral vector, named AAV2.5, was created from a type 2 AAV capsid with five mutations from AAV type 1. It combines the good ability to penetrate muscle cells characteristic of AAV1 with reduced cross-antigenic reactivity towards both parent serotypes, while maintaining the binding characteristic of AAV2 to cell receptors.
During the first trial, the new virus was injected into six boys with Duchenne muscular dystrophy. Duchenne muscular dystrophy is an X–linked hereditary disease that affects one in 4,000 newborn boys.
The virus carries the dystrophin protein gene, which is absent in patients with this disease, which is the cause of progressive muscle weakness. Viruses containing this gene were injected into the biceps of one arm, and a placebo was injected into the other arm of each of the patients.
Scientists were able to detect new genes in all patients who received such therapy, and did not observe any immune response.
However, higher doses of the virus may be required to obtain a therapeutic effect, which may cause an undesirable reaction from the immune system. Therefore, now, preparing for the next phase of trials, Professor Samulski and his colleagues are carefully studying a number of different options for the introduction of viruses to patients, including a new technique of intravenous injection under high pressure, developed by UNC Professor of neurology William J. William J. Powers, which allows genes to be delivered to muscles using lower doses of the virus.
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13.12.2011