Stem cells regrow damaged nerves in rats: study

Stem cells taken from mouse embryos have helped paralyzed rats move again, researchers said on Monday.

The study was the best evidence so far that controversial embryonic stem cells might be used to treat people with spinal cord and other traumatic injuries, the researchers said.

"This study provides a 'recipe' for using stem cells to reconnect the nervous system," Dr. Douglas Kerr of The Johns Hopkins University School of Medicine said in a statement.

"It raises the notion that we can eventually achieve this in humans, although we have a long way to go ... We found that we needed a combination of all of the treatments in order to restore function."

Kerr and colleagues used a soup of compounds called growth factors to cause stem cells from the mouse embryos to develop into a type of nerve cell called a motor neuron.

Writing in the Annals of Neurology, they said the transplanted cells, combined with the right mix of compounds, helped paralyzed rats regrow some of their nerve cells and use their hind legs.

"This work is a remarkable advance that can help us understand how stem cells might be used to treat injuries and disease and begin to fulfill their great promise," said Dr. Elias Zerhouni, director of the National Institutes of Health, which funded the study.

Stem cells are the body's master cells and can be found circulating in the blood and in tissues. Scientists hope to learn to use them to regenerate cells, organs and tissues.

A controversial source of the stem cells comes from days-old embryos. These stem cells have the ability to change into any type of cell or tissue in the body.

Opponents of their use say experimenting on human embryos is morally wrong, and U.S. law prevents the use of federal funds to create or work with all but a few batches of human embryonic stem cells.