Oct 30 1998
WESTPORT, Oct 30 (Reuters Health) - Contrary to long-held beliefs, neurons in the human brain do replicate in adulthood, according to a report in Nature Medicine for November. The finding has long-term implications for treatment of Alzheimer's disease and other neurodegenerative disorders, a multinational team says.
Researchers have shown that neurogenesis occurs in the brains of mature rodents, particularly in the dentate gyrus region of the hippocampus. Dr. Fred H. Gage, of The Salk Institute for Biological Studies, La Jolla, California, and colleagues in Sweden investigated whether neurons also regenerated in the adult human hippocampus.
Dr. Gage and colleagues took postmortem brain tissue from five cancer patients who had been treated with bromodeoxyuridine, a thymidine analogue that is sometimes used to check for tumor cell proliferation. Bromodeoxyuridine is incorporated into the DNA of dividing cells and is detectable in tissue using standard immunohistochemical techniques.
"Using immunofluorescent labeling for [bromodeoxyuridine] and for one of the neuronal markers, NeuN, calbindin or neuron specific enolase (NSE), we demonstrated that new neurons, as defined by these markers, are generated from dividing progenitor cells in the dentate gyrus of adult humans," they write.
The researchers note that the biological significance of cell genesis in the brain is not clear. They suggest that the presence of progenitor cells in the human dentate gyrus opens avenues of research that could lead to new therapeutic approaches.
Dr. Zaven Khachaturian, director of the US Alzheimer's Association's Ronald and Nancy Reagan Research Institute called the finding "extremely exciting."
"The study begins to shatter some long-held myths about the brain, that it is not capable of repairing itself," he told Reuters Health. "I think that is very important because it indicates that it will be possible one day to restore lost functions of the nervous system, whether lost due to Alzheimer's disease or some other degenerative process. The finding has great implications far beyond Alzheimer's disease."
Although he noted that "...we are a few steps removed from practical application," Dr. Khachaturian speculated that "...one scenario might be finding a way to reactivate the genes that were active during development and start the whole process of cell division over again. Another might be to transplant cells or deliver the cells somehow."
Nature Medicine 1998;11:1313-1317.
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