Promising results in mice need to be repeated in humans, experts say
WEDNESDAY, Oct. 10 (HealthDay News) -- Researchers say they've made new strides in harnessing the body's natural ability to reverse nerve damage wrought by multiple sclerosis.
According to the U.S. team, a single low dose of a human antibody administered to laboratory mice repaired myelin, the protective sheath that covers nerves. Multiple sclerosis wreaks havoc with the nervous system by stripping away this outer covering.
"This is an exciting first step in increasing our knowledge of repair in multiple sclerosis using a unique approach," said Patricia O'Looney, vice president of biomedical research programs at the National Multiple Sclerosis Society (NMSS) in New York City, which helped fund the research.
The findings were presented Tuesday at the annual meeting of the American Neurological Association, in Washington, D.C.
In healthy individuals, damage to myelin repairs itself naturally. But in people with MS and other disorders of the central nervous system, myelin repair occurs either slowly or not at all. As a result, the flow of information between the brain and the rest of the body is impaired, resulting in movement problems.
Some 400,000 people in the United States and 2.5 million people globally have been diagnosed with MS, most of them between the ages of 20 and 50, according to the NMSS.
"The challenge for researchers in trying to get a cure is, how do we repair myelin and restore function?" O'Looney said.
There is some evidence that cells that produce myelin are still present around damaged areas. As O'Looney put it, "The cells are already there, so how do you stimulate them to do what they're supposed to be doing?"
For this study, researchers at the Mayo Clinic in Rochester, Minn., genetically engineered a special antibody, called rHIgM22. This antibody binds to myelin and the surface of cells in the brain and spinal cord, prompting those cells to begin the process of remyelination.
The antibody is the first known compound to spur repair by acting within the central nervous system.
Laboratory mice that received a single dose of the antibody experienced remyelination that plateaued within five weeks.
When combined with a steroid (often prescribed for patients with MS), the antibody continued to promote remyelination, the research team said. Most human patients who might receive the antibody one day in the future will have already been treated with this steroid, they noted.
The antibodies did not appear to have any side effects, even at 4,000 times the minimal effective dose.
The Mayo team will eventually have to replicate the findings in humans before the concept can become an effective therapy, experts say.
"This approach is trying to use a naturally occurring molecule in our body in such a way that it binds to the cell and triggers signals within the cell to begin the repair process," O'Looney said. "This is a very exciting area of research in MS. How do you stimulate natural repair? How do you stimulate cells already there to repair the damage that's done? This is a unique, different way of approaching that, and it seems to be very successful in one of the animal models of MS."
For more on multiple sclerosis, visit the National Multiple Sclerosis Society.
SOURCES: Patricia O'Looney, Ph.D., vice president, biomedical research programs, National Multiple Sclerosis Society, New York City; Oct. 9, 2007, presentation, American Neurological Association annual meeting, Washington, D.C.
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