For the first time, Yale scientists have transplanted stem cells from an adult primate brain to repair the insulating sheath surrounding spinal cord axons in the same animal. These results, reported at the annual meeting of the Society for Neuroscience in November, raise hopes that patients’ own stem cells might one day be used to help them recover from spinal cord injuries or multiple sclerosis.

For the experiment, which was directed by Jeffery D. Kocsis, Ph.D., professor of neurology and neurobiology, a small quantity of cells was removed from the subventrical zone in the frontal lobe. The neural precursor, or stem, cells were then cloned and expanded in the laboratory before being transplanted into a region of the spinal cord from which myelin, the protective coating around the nerve fibers that increases impulse conduction speed, had been removed. The stem cells formed new myelin to cover the nerve cells.

The use of a subject’s own stem cells could circumvent the ethical and practical issues surrounding the use of fetal tissue, from which stem cells can readily be derived, and the problems associated with immune suppression that arise when transplanting foreign tissue. In the January issue of Experimental Neurology the investigators further reported that similar cells derived from the adult human brain can repair axons in a rodent model of demyelination and improve impulse conduction.

“The concept is not ready for application in patients, but the fact that it can be achieved in a primate and that the stem cells can be developed from adult human brain is significant. There’s a lot of excitement here about the potential of putting cells to work to repair the injured nervous system,” said Kocsis. But, he warned, “There are so many cell types and so many safety issues. This is the very first step in a long process for developing new clinical treatments.”