The first patient in a gene therapy trial for Alzheimer's disease, 63-year-old Ron Shellady, was treated recently at Rush University Medical Centre in Chicago, US. The two-year study will assess the safety of the technique, on 6-12 participants with a mild to moderate form of the disease. The scientists are aiming to deliver the nerve growth factor (NGF) gene to the patients' brains, in the hope that it will trigger cell growth, and repair some of the damage caused by the disease.
Alzheimer's disease is the most common cause of dementia, affecting one in twenty people over 65, and more than one in ten of those over 85. The disease symptoms are caused by the gradual death of certain brain cells, especially in the areas involved in memory. The gene therapy treatment involves injecting a harmless virus carrying the NGF gene directly into the brain, particularly a region called the basal forebrain. Cells in this area produce most of the brain's supply of a crucial memory chemical called acetylcholine, levels of which fall in people with Alzheimer's disease. The scientists hope that by targeting this region, they can raise the levels of acteylcholine throughout the brain, alleviating the effects of the condition.
The study builds on earlier work by a team at the University of California, San Diego, who took skin cells from patients and grew them in the laboratory. They then modified these cells with the NGF gene, before injecting them into the brain. Although their results were encouraging, the Rush scientists say in a press release that they should be interpreted with caution, since it was a small study and did not include any controls.
Meanwhile, scientists based at the Children's Hospital in Boston and Harvard Medical School say they have developed a new method of controlling therapeutic genes delivered to the body. The system, outlined in the latest issue of Nature, involves adding a piece of DNA to the gene that can potentially disable the resulting mRNA (messenger RNA) - the intermediate between a gene and the protein it codes for. The scientists say that in this way, it should be possible to switch genes on and off, using drugs that stop this process. 'With recent concerns about the development of leukaemia in several children treated with gene therapy, this method adds an important new safety feature to the gene therapy toolbox', said team leader Richard Mulligan.
Sources and References
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Rush uses gene therapy in Alzheimer's battle
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New gene therapy technique may help treat Alzheimer's disease
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Safer route to gene therapy found
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A novel, safer strategy for regulating gene expression
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Trial gives hope to Alzheimer's sufferers
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