|Abracadabra: Bone Marrow Cells Turn into Brain Cells|
|By Ellen Kuwana |
Neuroscience for Kids Staff Writer
January 23, 2001
You may have seen the famous performer David Copperfield appear to change a car into an elephant. Neuroscientists appeared no less magical when they transformed blood cells into brain cells. Two research groups reported in the December 1 issue of Science that bone marrow cells can travel to the brain and turn into nerve cells.
Bone marrow, the soft material inside your bones, is composed of at least
two types of
In order to trace what happens to the transplanted cells, scientist need a marker, something that identifies the transplanted cells from the cells that were already there. Think of it this way: if you released some ants into an antpile and wanted see where they would go, you would need a way to trace their route. For example, if you put red ants into an antpile that housed black ants, it would be easy to see where your red ants went.
The first team of scientists, led by Helen Blau at Stanford University, used adult bone marrow cells that contained a green protein that glows in the dark: green flourescent protein or GFP. The host mouse's own bone marrow cells were destroyed by radiation, so the mouse needed donor bone marrow in order to make the cells that make up blood (similar to people who undergo radiation therapy for cancer, and then need a bone marrow transplant). Adult donor cells were injected into the tail vein of the adult host. One to six months later, when the researchers examined the brains of the mice, they were surprised to find GFP inside brain cells, meaning that these cells had originated from the bone marrow. What's more, these cells in the brain looked like nerve cells and were making proteins that nerve cells make. In other words, the transplanted cells were able to respond to signals in the brain that told them to change into brain cells. Abracadabra...from bone marrow cells to brain cells!
The second team of scientists, led by Eva Mezey of the National Institute of Neurological Disorders and Stroke (NINDS), used a different method to trace the bone marrow cells. They exploited the difference between males and females: males have XY chromosomes and females have XX. The researchers used donor bone marrow cells from adult male mice (XY) and injected the cells into newborn female mice (XX). When examining the brains of the female mice, any cells containing a Y chromosome had to be from the donor cells. Indeed, cells containing Y chromosomes were found in the brain. Although it had been observed before that bone marrow cells could become astrocytes and glial cells ("support"cells in the brain), no one expected a change to nerve cells.
|Much more work needs to be done. The bone marrow cells seem to
changed into nerve cells, but are these cells truly nerve cells? They
appear to be making proteins that nerve cells make, but this is not
definite proof that these cells are acting as nerve cells. Here are some
questions that still need answers:
|One advantage of this approach as a treatment for disease is that
cells would come from a patient's own body. In other words, a patient's
bone marrow cells would be used to make his or her brain cells. Thus,
there would be no donor-host incompatibility, such as that sometimes seen
in organ transplants where the host's body rejects the foreign tissue.
This means that there would be no need for immunosuppression, where drugs
are used to quiet the immune system, thus leaving the patient vulnerable
to life-endangering infections.|
Any step forward in understanding the complicated mechanisms underlying cell differentiation, cell migration, and the various signals that guide these processes is a step towards treatment for diseases characterized by loss of nerve cells. This includes therapies for disorders such as Parkinson's disease, Huntington's disease, and stroke.
References and further information:|
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