Wed April 16, 2003 05:32 PM ET
By Rossella Lorenzi
Injecting adult stem cells into mice repairs damage similar to that seen in multiple sclerosis, according to Italian researchers who say their work could one day offer hope for treating the disease in humans.
Investigators at the San Raffaele Scientific Institute in Milan report in Thursday's issue of the journal Nature that brain stem cells injected into the brains or veins of mice with an experimental form of the disease repaired nerve damage and, in many cases, improved symptoms.
In multiple sclerosis, nerves in large parts of the brain and spinal cord lose their insulating myelin sheaths due to an abnormal immune system assault, which damages the conduction of electrical nerve impulses.
The resulting symptoms include muscle weakness, visual disturbances, lack of coordination, and abnormal skin sensations. About 1 million people worldwide have the disease, which occurs in twice as many women as men.
Dr. Gianvito Martino and Dr. Angelo L. Vescovi injected neural stem cells from adult mice into mice with an experimental form of multiple sclerosis. Stem cells are immature cells that have the capacity to develop into a variety of mature cell types. Brain stem cells are now known to be present in adult brains, and in the study, the researchers used neural precursor cells collected from adult mice.
"Thirty percent of mice recovered, 70 percent improved significantly," Martino said at a press conference on Wednesday.
"The novelty of this study is the possibility to induce myelin repair in multiple areas of the brain and spinal cord by transplanting brain stem cells not only directly within the central nervous system, but also into the blood circulation."
Within 30 days of injection, the stem cells homed in on the damaged area and proceeded to mature into myelin-producing cells.
The researchers said that the stem cells reached damaged areas thanks to specific "adhesion molecules" on their surface, which allow them to sense danger signals, pass through the protective blood-brain barrier and repair damaged areas.
"We realized that the donated cells have a key to pass through the blood brain barrier and enter into the central nervous system. This was the first step to other amazing discoveries," Martino told Reuters Health.
"But there is more," he said. The results show that stem cells not only repair damaged areas themselves. They also trigger naturally occurring myelin-producing cells to repair the lesions.
The researchers stressed that the work is at an early stage, but within
two months, Martino and Vescovi plan to begin non-human primate studies.
Potential therapeutic applications for humans might take five to 10 years,
© Reuters 2003