Stem Cells Regenerate Nerves in Rats

WASHINGTON (AP) — Scientists know that injecting paralyzed rats with human stem cells can help the animals regain some motion. Now they know why: The injection helped many of the rats’ dying nerve cells to survive.

That’s not what the researchers had expected to discover.

Stem cells are master cells found in human embryos that give rise to all human tissue. Scientists hope to one day harness stem cells for revolutionary therapies, such as regrowing damaged spinal-cord cells to treat paralysis.

In one such experiment, scientists at Johns Hopkins School of Medicine injected rats with a virus to paralyze them, simulating Lou Gehrig’s disease. Then the rats were injected with human stem cells. The treated rats regained some ability to move their feet, an experiment that made headlines several years ago.

The question was why.

The stem cells did grow some new nerve cells, but too few to explain the animals’ motion, said lead researcher Dr. Douglas Kerr, who reports what really happened Friday in the Journal of Neuroscience.

It turns out that the stem cells traveled toward the worst-injured spots of the spinal cord, something cells won’t normally do. Once in place, they churned out chemicals that helped original neurons teetering on the brink of death to survive and to re-form the connections between them necessary for muscle movement.

That’s good news – because saving existing nerve circuits should be easier to accomplish than rewiring the whole spinal cord, Kerr said.

But human studies of stem cells for such complex diseases as Lou Gehrig’s likely are still five years away, Kerr cautioned.

—–

On the Net:

Johns Hopkins School of Medicine

More science, space, and technology from RedNova

Copyright © 2003 The Associated Press. All rights reserved. The information contained in the AP News report may not be published, broadcast, rewritten or redistributed without the prior written authority of The Associated Press.