Nov. 30 (CBSHealthWatch)--Bone marrow cells could migrate to other parts of the body--such as the brain--and become new brain cells, according to two new research studies performed by two separate groups.

Both studies found that in mice, cells that were formerly bone marrow cells had moved into the brain and began working as brain cells. The two articles on the studies are both published in the December 1 issue of the journal Science.

Although both groups stress that their studies were only done in mice, they note that if they apply to humans as well, the findings could one day be useful for treating injuries or diseases affecting brain cells.

One set of researchers was led by a Mezey, MD, PhD, of the National Institutes of Health's National Institute of Neurological Disorders and Stroke, while the other group came up with their findings at Stanford University, in the lab of Helen Blau, PhD, professor and chair of the university's department of molecular pharmacology.

"It was totally unexpected that cells from the bone marrow--that are destined to make the blood of the body--could change and give rise to cells that have neuronal characteristics in the brain. Nobody ever expected that--especially us," says Blau.

Blau says she has long been interested in whether cells have a certain fate, or if they can change and become other kinds of cells. Earlier, she found that cells can be manipulated to become other kinds of cells, but this new research shows something else. "This goes further in that it says that it happens normally," Blau says.

They transplanted bone marrow from mice with green fluorescent protein in all of their marrow--"they glow in the dark," Blau explains--into mice without any of their own bone marrow. Then, they tracked where the donor cells traveled in the body.

Initially, they had planned to follow up on previous research involving bone marrow cells that had moved into bone tissue. One day, Blau says, the graduate student doing much of the research--Timothy R. Brazelton, the lead author of the Science article--discovered that it looked like the marrow cells had moved into the brain.

"We went through the most rigorous process determining if this was really the case," Blau says. "They had really changed."

Mezey's team of researchers used a different method to transplant and monitor donor bone marrow, but they also found that marrow cells had moved into the brain and began working as brain cells.

They used special mice that are born without their own bone marrow, but will lead a normal life if they receive a bone marrow transplant at birth. To track the marrow cells throughout the mice's bodies, Mezey's group only used female mice, and only used bone marrow taken from male mice for the transplantation.

"Since the Y chromosome is specific for males, any cell that bears the Y chromosome in the recipient animal must have come from the bone marrow," Mezey explains. "Then at different time points after the transplantation, we went into the brain and looked for Y chromosome-containing cells. Then when we found them, we ?tried to identify what kinds of cells they are."

This method could prove more useful than stem cell projects using fetal cells or embryonic cells, both researchers note. "If this works more effectively, it has several advantages in that you use a person's own cells, so there's no immune response, and also, if you could do it via the blood you don't have to poke holes in the brain. But these are all 'ifs,'" Blau says. More research by different groups is needed to study the matter further and determine just how the process works, and if it can work in humans.

Both Blau and Mezey agree, however, that it is vital that embryonic stem cell research continues, since that knowledge will also be important.

The new findings could hold real promise for the future, Blau says. "The fact that they can do it is very exciting because if we can learn what the signals are that make them go to certain regions of the brain and make them change once they get there, then we could harness that and repair damage, treat disease--and that's what we want to do," she says.

But Mezey cautions that that day will probably not come soon. "I do think that it will be useful in the future, it just will not be tomorrow," she says.

(From CBSHealthWatch)