November 6, 2000
Web posted at: 11:10 AM EST (1610 GMT)
NEW ORLEANS, Louisiana (AP) -- Mice paralyzed by a virus were able to move their feet -- and a few were even able to stand again -- after versatile stem cells were injected into the fluid around their spinal cords in a medical study.
Any studies in people are years away, but the work offers some hope for spinal motor atrophy -- the most common inherited cause of infant death -- and for Lou Gehrig's disease.
The study was the first time researchers had restored some function when the entire spinal cord was damaged, said Dr. Douglas Kerr, an assistant professor of neurology and lead researcher for the project at Johns Hopkins in Baltimore, Maryland.
A few mice that had been injected with Sinbis virus, which kills some nerves that control motion and creates permanent paralysis in the hind legs, were able to step after receiving the versatile stem cells injection, but most had more limited movement, he said.
Twelve of the 18 animals injected with the stem cells were able to at least twitch their hind legs.
Even small movements would mean a lot to people who had no movement before, said Dr. Jeffrey Rothstein, also of Johns Hopkins, who discussed the research Sunday at the annual meeting of the Society for Neuroscience.
Other scientists discussed stem cell experiments on rats with induced strokes, traumatic brain injuries, spinal cord injuries, and monkeys with damage to the myelin coating around nerves in the spinal cord.
"If you're thinking that any of these models means patients can get up and run again, you're in fantasy land," Rothstein cautioned.
Still, enough muscle control to get someone off a ventilator and breathing without mechanical help would be "very, very pleasing," said Jeffery Kocsis of Yale.
Stem cells are immature cells which can duplicate themselves and grow into different kinds of mature cells.
Kocsis described the myelin work, which might someday help people with spinal injury or multiple sclerosis, in which the immune system goes wrong and attacks the myelin insulation protecting nerves.
Without myelin, messages traveling down nerve cells may be blocked entirely, or their timing may be wrong. In multiple sclerosis, the damage builds up over years, causing muscle weakness or paralysis, fatigue, dim or blurred vision and memory loss.
Kocsis used a chemical to remove myelin from a nerve location which he said caused abnormal -- but not painful -- sensations in marmosets. After stem cells were injected at that spot, new myelin formed on the nerves. The study shows that the technique is feasible in primates, he said.
In another area, Kocsis said Yale is working toward human safety studies of related cell therapy -- taking Schwann cells, which create myelin, from a patient, growing large numbers of them in the lab, and then transplanting them back to the same patient.
Kerr, interviewed before the conference, said there are a number of major steps before any human tests begin on stem cell therapy for Gehrig's disease, or ALS, which affects about 20,000 people, and spinal motor atrophy, which may affect as many as one in 6,000 babies.
"I think the most important thing we need to do is make sure the cells don't potentially hurt people. ... Make sure they don't become tumorous, for example, or differentiate into tissue we don't want," he said.
Copyright 2000 The Associated Press.