In one patient, the brain tissue showed new growth, which was a first, according to a study published in yesterday's edition of the journal Nature Medicine.
''It won't cure the disease," said the lead researcher, Dr. Mark Tuszynski of the University of California, San Diego. That is because Alzheimer's destroys different types of cells in different areas of the brain; the new gene therapy targets just one of those.
The preliminary success indicates that similar approaches might help other neurodegenerative diseases, such as Parkinson's, Tuszynski said. ''This is, in a sense, proof of principle for the potential use of growth factors," he said.
Doctors at Rush University Medical Center in Chicago have begun a second small study of the approach in Alzheimer's patients. Tuszynski, who cofounded a biotechnology company funding the Chicago work, hopes larger studies will begin within another year.
Tuszynski and colleagues took skin cells from eight patients in the early stages of Alzheimer's and modified the genes to secrete a protein found in healthy brains called nerve-growth factor, or NGF.
Earlier studies had shown that injecting NGF-producing tissue into the brains of aging monkeys could reverse deterioration, but injecting NGF into people would not work. If it goes into the wrong part of the brain, it can cause serious side effects.
So, doctors drilled holes into the patients' skulls and implanted the NGF-producing skin cells directly onto Alzheimer's-injured spots.
Six patients were tracked for almost two years. Tests involving memory and other skills found their rate of cognitive decline slowed by 36 percent to 51 percent, better than is usually seen with medication, Tuszynski reported.
The researchers said the therapy posed some risks for patients undergoing tests. The first two patients were awake and moved during the cell implantation, causing bleeding in their brains; one patient died five weeks later.
The remaining patients received the implants under general anesthesia to keep them still, and the researchers reported no further problems. The team said that approach would be tried in tests on a larger group of patients.
