December 19, 2001
By HELEN BRANSWELL -- Canadian Press
TORONTO (CP) -- Is multiple sclerosis reversible? Can the body be prompted to regenerate myelin and repair the damage the disease inflicts on the central nervous system?
Those are some of the questions a team of researchers from Canada and the United States are attempting to answer in a three-year, $3.5-million research project being led out of Montreal's McGill University.
At the core of the project is the idea that there may be ways to prompt stem cells in the brain to turn into cells that produce myelin, which would then encase anew the nerve cells left exposed by the ravages of multiple sclerosis.
"At one point they were clever enough to make myelin. Why aren't they clever enough now?" explained Dr. Jack Antel, who is co-ordinating the research program that involves top MS scientists at McGill, the universities of Calgary and Toronto, the Mayo Clinic and the University of Rochester in New York.
Among the questions the researchers will have to answer is why isn't the body doing this regeneration itself, if cells with this potential already exist in the brain.
"Is it that as the body has developed, that the environment is such that it is holding back that process? And there may be reasons why it wants to hold back that process. So if the environment is keeping the system under control, change the environment and boost the process," said Antel, a clinical neurologist who is co-ordinator of the MS program at the Montreal Neurologic Institute, one of McGill's teaching hospitals.
Multiple sclerosis is the most common disease of the central nervous system to strike young adults in Canada, affecting an estimated 50,000 people in this country. Women are slightly more likely to develop the disease than men.
The degenerative disease causes a wide range of unpredictable symptoms that may include vision disturbances, extreme fatigue, balance and speech problems, even paralysis.
MS is believed to be caused by a malfunction of the body's immune system, which when working properly protects one from invading germs and bugs.
In people with MS, the immune system mistakenly attacks one's own myelin, the substance that coats and protects nerves in the brain and spinal cord. The result is that messages between nerve cells -- "Pick up the fork" for instance -- slows down and becomes irregular.
Much research has been done to try to find ways to shut down the destructive process. But until recently, little effort was aimed at trying to find ways to help repair the damage the disease causes.
Antel said the thinking was that until science could stop the destruction of the myelin sheath, there was no point trying to create new myelin.
But that time has come, he believes. He and his colleagues are betting that stem cells provide the answer and they've persuaded the Multiple Sclerosis Scientific Research Foundation -- an offshoot of the MS Society of Canada -- to fund their quest.
Also known as progenitor cells, these are primitive cells that have the potential to develop into any type of cell in the body -- brain cells, heart cells, or liver cells, for instance.
"You can think of them at the level of cells that haven't decided what they want to become," Antel explained.
Because of their huge potential, stem cells are the subject of a vast amount of research into a wide range of ailments.
There are two basic approaches to stem cell research. One involves transplanting stem cells from an external source into a recipient -- a controversial line of research as the stem cells are taken from fetuses. The second involves tapping the potential of the body's own stem cells.
Antel and his colleagues have opted for the latter, side-stepping both controversy and the tricky problem of getting the cells to the site of the injury.
But they must figure out ways to trigger differentiation -- the process by which a stem cell chooses to become a distinct type of adult cell.
Researchers at the University of Toronto and the University of Rochester are trying to figure out whether there are growth factors that could be used to encourage the stem cells to become myelin-producing cells.
Other members of the team are trying to figure out why some stem cells begin the process of differentiation into myelin-producing cells but stop at an immature level. (There is evidence that some remyelination happens naturally, but the body appears unable to keep pace with the destruction wreaked by the disease.)
They also want to find out whether the partially differentiated cells are a more promising target than the totally undifferentiated stem cells.
Still another, at the Mayo Clinic, is trying to figure out if there are ways to significantly increase the numbers of these types of cells, which appear to be in limited supply in the brain.
If the research proves fruitful, it will be a key compliment to existing therapies aimed at shutting down the disease process. That's because considerable damage to the central nervous system is already done by the time doctors realize someone has multiple sclerosis.
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