Raising hopes of a treatment for multiple sclerosis, researchers have found that stem cells injected into mice can repair damage and sharply reduce symptoms from an experimental form of MS.

Seven of 26 mice recovered completely from hind-leg paralysis and others showed substantial improvement after the stem cells were injected into their spinal cords or blood.

The study’s authors, from the San Raffaele Scientific Institute in Milan, Italy, say they now plan to try the procedure on monkeys using human stem cells, but caution that a treatment for human patients, if possible, is years away.

Multiple sclerosis occurs because the body mistakenly attacks the fatty substance that surrounds nerve fibers, interfering with signals sent by the brain. Symptoms can include slurred speech, numbness, blurred vision and muscle weakness, spasticity or paralysis.

About 400,000 Americans, mostly women, have MS, and most are diagnosed between the ages of 20 and 50, according the National Multiple Sclerosis Society. Current therapies help slow the disease by quieting the immune system attack on nerves, but no cure is known.

In the mouse experiment, researchers used stem cells that had been removed from the brains of adult mice and grown into larger quantities in a laboratory.

Once injected, the cells traveled to damaged nerve areas and changed into cells needed to make repairs, according to the study published in Thursday’s issue of the journal Nature.

Research on monkeys is expected to begin in the next few months, and the results are expected by the end of 2004, said Gianvito Martino, one of the study’s authors.

“This opens new hope for patients, but the way is very long and very hard,” Martino said.

The research raises the hope of reversing the damage caused by the disease, but does not address the cause, said Stephen Reingold, the MS society’s vice president for research.

One impressive aspect of the approach is that the cells seem to seek out the damaged areas themselves, which is important because MS affects the entire central nervous system, Reingold said.

“This doesn’t tell us it’s going to work in humans, but at least it’s a step forward,” Reingold said.

If the work does eventually proceed to experiments with people, human fetal cells are most likely to be used, said Angelo Vescovi, one of the study’s authors. Such cells will be used in the monkey study.

Vescovi said laboratory populations of such cells can be established with tissue from spontaneous miscarriages. Tissue matching will probably keep the recipient’s body from rejecting them as foreign, Vescovi said.

Dr. Lawrence Steinman, a Stanford University neurologist, said overcoming rejection might not be easy because MS is an autoimmune disorder in which the body is already attacking its own tissue.

“I think a huge amount of research has to be done to figure out the conditions to do this in humans, to grow the types of cells that work so splendidly in mice,” Steinman said.

“You have to have a way of shutting off the autoimmune disease if the process is ever going to work,” he said. “On top of that, if they (the injected cells) are recognized as foreign, the immune system will also attack.”

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On the Net:

Nature: http://www.nature.com/nature

MS Society: http://www.nmss.org

AP-ES-04-16-03 1423EDT

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