FRIDAY, April 30, 2004 (HealthDayNews) -- It appears that after a bone marrow transplant, some of the transplanted blood stem cells can become brain cells, researchers report.
This finding suggests a patient's own bone marrow might be used as a source of stem cells to regenerate lost nerve cells.
Stem cells are cells that have not yet become a specific type of cell; the potential exists for them to become any kind of body cell.
If a way can be perfected to deliver these cells directly to the brain, transplanted blood stem cells might provide treatments for neurodegenerative diseases and traumatic brain injury.
"Blood can make brain," said lead researcher Dr. Christopher R. Cogle, a postdoctoral associate from the University of Florida. "The brain is not a static organ. It does have some regenerative capacity."
"We wanted to see if the transplanted bone marrow cells contributed to the production of new neurons," said co-researcher Dr. Eric D. Laywell, an associate professor of anatomy and cell biology at the University of Florida.
The research team looked at brain tissue from three women who had received bone marrow from male relatives to help treat leukemia. They found male Y chromosomes in the brain tissue of all three women.
But the woman who survived the longest had three different types of male brain cells, including microglia, neurons and astrocytes.
"In this woman, we found neurons that had both X and Y chromosomes, which means that they came from the transplanted male bone marrow," Laywell said.
The male neurons made up 1 percent of the neurons in her hippocampus, according to the report in the May 1 issue of The Lancet.
"It appears that adult blood stem cells have the capacity to make other cell types," Cogle said. He noted these new cells were not male stem cells that were fused to female cells, but were newly created brain cells.
"If it is possible for bone marrow to turn into nervous tissue, then everybody is walking around with a potential replacement source of nervous system cells," Laywell said.
The next step in the research is to try to find ways to make adult blood stem cells repair the brain in a much more robust way. "We need to find what signals blood cells to go into the brain and make brain cells," Cogle said.
"Our findings imply that blood stem cells may be a source for repairing an injured brain in patients with Alzheimer's or Parkinson's or brain trauma," he added.
"Every time I spend time with my grandmother, who has a neurodegenerative disease, all I can hope is that our center and other centers work as hard and as fast as we can to help find a cure," Cogle said.
Dr. Neeta S. Roy, an assistant professor of neurology from Weill Medical College of Cornell University, said this finding is "amazing." It is the first demonstration that confirms that blood stem cells can become neurons, she added.
However, "even though these cells look like neurons, it doesn't mean that they are functioning neurons -- neurons that can actually do something, like heal brain damage," Roy cautioned.