New sources and uses for stem cells.

Neural stem cells stole the show in New Orleans. In talks and other presentations, dozens of neuroscientists suggested new ways to obtain and use these immature cells that can give rise to neurons and the brain's other cells.

Scientists once thought that neural stem cells exist only in young, developing brains, but compelling evidence has emerged that adult brains also harbor such cells. Researchers even have found that human bone-marrow cells can give rise to neurons (SN: 9/2/00, p. 155).

A research group led by Freda Miller of McGill University in Montreal now reports than human skin and scalp tissue may provide a source of neural stem cells. The investigators report they induced skin- and scalp-derived cells to form neurons and other brain cells in laboratory dishes.

"It's absolutely fascinating. There are stem cells in a variety of places in the body that have the capability of giving rise to neurons," says Ira Black of the Robert Wood Johnson Medical School in Piscataway, N.J., who led the bone-marrow work.

Both Miller's and Black's findings suggest that physicians could use a person's own tissue to grow replacement brain cells, which the patient's immune system would tolerate instead of rejecting. Both research groups continue to test whether the neurons derived from the bone marrow and skin cells behave normally. It remains unclear which tissue offers a better stem cell source. "The more potential sources we have, the greater probability we'll be able to help people," says Black.

According to work presented in New Orleans, people who may benefit from neural stem cells include those with strokes, spinal cord injuries, brain trauma, and Alzheimer's disease. For example, Tracy McIntosh, director of the head injury center at the University of Pennsylvania in Philadelphia, reported that brain-derived stem cell transplants improved movement in mice with brain damage similar to that suffered by people in car crashes.

Using a similar transplant strategy, Evan Y. Snyder of Harvard Medical School in Boston has had some success treating stroke-induced brain damage in rats. Rodents receiving neural stem cells recover more mobility than do untreated animals. "The cells seem to home in on areas of injuries," says Snyder.

Snyder's group even found that neural stem cells in rodent brains migrate to abnormal protein deposits that resemble the ones in the brains of Alzheimer's patients, suggesting that the cells could replace neurons killed by the disease. Several research teams also reported animal studies showing that neural-stem cell transplants help injured spinal cords regrow new nerve connections or repair existing ones.

-- J. T.