Stem cells continue to reveal new tricks. Researchers now report that they have coaxed these multitalented cells to repair a certain type of nerve damage in rats. If the technique is honed and works in humans, a similar strategy might eventually help people with multiple sclerosis or spinal cord damage.
Embryonic stem (ES) cells are derived from early embryos and can become any tissue in the body. In the past few years, researchers have seen tantalizing glimpses of potential applications for treating liver disease, amyotropic lateral sclerosis, and diabetes. But perhaps the most promising work has involved spinal cord injuries. Last year, neuroscientists John McDonald and Dennis Choi of Washington University in St. Louis and their colleagues showed that when they injected cells derived from mouse ES cells into rats with damaged spinal cords, the rats regained some mobility (ScienceNOW, 30 November 1999 ).
The scientists suspected that the injected cells had developed into a type of cell called an oligodendrocyte, which produces a myelin sheath that covers nerves and helps them to transmit signals. New evidence suggests that this explanation is correct, McDonald and his colleagues report in the 23 May issue of the Proceedings of the National Academy of Sciences. In one experiment, cells were injected into rats that had been treated with a chemical that destroyed spinal cord myelin. When the researchers examined the spinal cords a week later, they found that the injected cells had turned into oligodendrocytes. In another experiment, the team injected ES cell derivatives into adult rats that lacked myelin in their spinal cords. After two weeks, it appeared that some myelin had grown.
The work suggests that ES cells may indeed become a useful treatment for patients with myelin damage, including those with spinal cord injuries and multiple sclerosis, McDonald says. Although others have shown that ES cells can become myelin-producing oligodendrocytes in fetal animals, it's useful to show that it works in adults too, notes neurobiologist Ron McKay of the National Institute of Neurological Disorders and Stroke in Bethesda, Maryland.