First gene therapy experiment for Alzheimer's
SAN DIEGO, California (CNN) -- In what is being called a medical first, doctors at the University of California, San Diego, announced Tuesday they performed gene therapy treatment surgery on an Alzheimer's patient.
The surgery was performed days ago on a patient with mild Alzheimer's disease. The therapy is not intended to be a cure, but it may protect or even restore brain cells and alleviate some symptoms such as short-term memory loss.
"Ideally we want to intervene as early as possible in this disease, before nerve cells degenerate," said Dr. Mark Tuszynski, the study's lead researcher at the University of California, San Diego.
The patient is a 60-year-old woman who is a former teacher from Oregon. She was diagnosed with Alzheimer's three years ago, and asked to remain anonymous.
Seven other patients will be involved in the initial study designed to assess the safety of the procedure. Researchers say if the gene therapy works, they may see memory or cognitive changes in the next several months.
"This is very interesting work since a lot of people have talked about doing gene therapy for Alzheimer's disease, but so far, no one's been able to work it out," said Bill Thies, Ph.D., with the Alzheimer's Association.
"However, we don't want to raise expectations that patients or family members will be able to get this treatment in the near future."
Skin cells taken from the patient were genetically engineered in the laboratory to produce and secrete human growth factor. In the surgical procedure, the genetically modified cells were implanted in the brain's frontal lobe, the area responsible for memory, thinking and reasoning. This area of the brain is referred to as the cholinergic system, which includes neurons that produce neurotransmitters, the chemical messengers used by the brain to process information. In Alzheimer's patients, the nerve cells in this system waste away and stop producing the neurotransmitters needed for normal functioning.
"In our study we need to answer two questions. First, whether preventing degeneration of this system is enough to improve cognition in Alzheimer's patients," said Tuszynski. "And second, will the nerve growth factor prevent death of cells from whatever is causing it."
Controversy remains over the exact cause of Alzheimer's disease. The leading theory is that the build-up of amyloid plaques in the brain begins the process of mental decline. The plaques consist of clusters of dead and dying nerve cells.
The rationale for beginning studies of this gene therapy in humans is based on 12 years of studies in rats and monkeys. Those studies showed the nerve growth factor gene therapy prevented the death of cholinergic cells and reversed aging cells.
"The functioning of these aging cells returned to normal," said Tuszynski. "We did see improvements in memory in old rats and young rats with brain injury."
The Alzheimer's Association said a major question to be answered is whether the implants will "take" in humans and remain "stable."
"It's possible the implants could start to divide and create a tumor setting," said Thies. "So there are certainly safety questions that will need to be answered."
A major challenge in treating Alzheimer's has been to find drugs that can cross the blood-brain barrier and reach the area of the brain that's affected by the disease.
"If this experiment works, it opens the possibility of delivering a number of drugs directly into the brain," said Thies. "The patient won't reject the genetically modified tissue since it's coming from the patient."
The UCSD researchers say they've selected the second patient who will undergo the procedure in the next three months. So far the team has received more than 500 inquiries from individuals interested in participating. To be eligible, patients must meet strict criteria including:
-- a neurologist-certified diagnosis of 'probably Alzheimer's disease'
-- early stage of the disease (generally within 2 years of diagnosis)
-- completely normal speaking ability and completely normal ability to understand what others are saying
-- ability to understand the potential risks of participation in the study
-- ability to travel to and from San Diego up to nine times in first year of study
-- willingness to discontinue use of FDA approved drugs Cognex or Aricept for the first 18 months of study.
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