Monday, October 14, 2002
By Clementine Wallace
Two new studies in mice strengthen hopes that stem cells may one day be used to treat brain injuries and brain degeneration in humans, according to researchers at Harvard Medical School.
Stem cells are immature cells capable of developing into different types of body tissue. In the study, researchers treated mice with neural stem cells, a type of cell found in the fetus and embryo that gives rise to all types of brain cells during brain development. Such neural stem cells can also be found in the central nervous system at all ages, although it's not clear if the cells play a role in brain repair.
When the researchers injected mouse-derived neural stem cells into injured or degenerated brain tissue in mice, they appeared to interact with the host cells and one another, according to Dr. Evan Snyder, professor of neurology at Harvard Medical School.
"The brain and the stem cells cross-talk and send messages to each other," he explained in an interview with Reuters Health.
In the first study, the researchers injected neural stem cells into the skulls of mice with severe damage to large areas of their brains. A similar type of damage occurs in people with severe cerebral palsy.
While stem cells on their own were unable to restore brain tissue, the researchers found that stem cells contained in a special "scaffold" of biodegradable material formed many interconnections with the host tissue. And as the scaffold broke down, new brain tissue supplied with blood vessels formed to take its place.
"In this case, the brain tells the cells to send out their connections and at the same time, the stem cells make the brain send connections to themselves and to the rest of the brain," Snyder explained.
In the second study, the team introduced neural stem cells into the brains of mice treated with chemicals to mimic the process of aging or Parkinson's disease in humans. In this case, the cells were found to "rescue" the dysfunctional neurons, which were reactivated.
"What these findings show is that stem cells and injured organs talk together in a way that allows reconstruction," said Snyder, "and we think that this process is not only applicable to the brain but also to the heart, the lungs or the gut."
These applications could one day be tested humans, according to Snyder, and would not require overly invasive procedures. "It would be an operation, but not a difficult operation," he said.
SOURCE: Nature Biotechnology 15 October 2002 doi:10.1038/nbt751; nbt750.
Copyright 2002 Reuters