Brain Cells Found to Regenerate

Medical science has always presumed that brain cells killed by physical trauma, stroke or other disease cannot regenerate. Victims of such brain injuries faced no hope of growing new cells to fulfill the function of dead cells, leaving their brains permanently impaired.
However, a landmark study in late 1998 by researchers from Sweden and the Salk Institute in La Jolla, Calif., showed for the first time that brain cells in mature humans can regenerate. The research was reported in the November issue of Nature Medicine.
Brain cell regeneration had been observed before in some lower mammals, but not in humans, monkeys or apes. More complex brains, it was thought, would be severely disrupted by new cell growth.
Working with terminal cancer patients ranging in age from 50s to 70s, researchers used a diagnostic agent that labels actively dividing cells. After the patients died, their brains were examined for the presence of the agent, which attaches itself to the DNA of new cells.
New cells were found. Though few in number, the new cells formed in an important part of the brain, the hippocampus, which is involved in learning and memory. The discovery raises hopes for even victims of Alzheimer's and Parkinson's diseases. And it is possible that new cell growth is substantially greater in younger, healthy adults.
Another issue to be resolved is whether the new brain cells will form networks, said Dennis Maiman, MD, professor of neurosurgery at the Medical College of Wisconsin who practices at Froedtert Hospital. For example, could the new brain cells establish networks through the scar tissue that forms following a stroke? And can other parts of the brain regenerate cells, too?
"I think this is very valuable research," Dr. Maiman said. "This is a huge piece of information. The discovery opens the door for the possibilities of future therapies for those who have experienced brain injuries."
One day, the mechanism to regenerate cells may be understood so that the brain can be directed to repair itself with new cells whenever and wherever it suffers trauma.