Growing Nerve Cells

Plan on wearing green this St. Patrick's Day? Bet you can't top a mouse with green skin. As this ScienCentral News video explains, this mouse is green for a very serious reason. It's invaluable to researchers learning how to grow nerve cells.

Glowing Green Mice

Even for scientists, it's not every day you see a hairless mouse glowing bright green under a fluorescent light. And for scientists searching for stem cells that could grow into nerve or brain cells, seeing such a mouse meant finding a possible whole new source of such cells.

The scientists had given the mouse a gene so that areas would glow green where such stem cells might be found. They expected part of the mouse around the head to glow green. Instead, the entire mouse was aglow. "I'll never forget the minute that we made that observation," says Robert Hoffman, president of AntiCancer, Inc., where the finding took place.

Because of that moment, which Hoffman says was, in fact, a "lucky discovery," company scientists have been working on what could be a new source of adult stem cells.

Their most recent research, published in Proceedings of the National Academy of Sciences (PNAS), shows that they've been able to use stem cells taken from a mouse hair follicle to help regenerate damaged nerves in mice. In previous research, also published in PNAS, they showed the stem cells could become special brain cells called neurons.

Hoffman says this trail of discovery began when they were trying to locate the source of adult stem cells for the brain. They were using a genetic modification technique that makes only the specific cells they're looking for glow green under fluorescent light. They expected to find appropriate cells somewhere around the brain. But when the entire mouse glowed, they knew there might be a promising source of stem cells elsewhere.
"So, we took a look at the skin under the microscope" says Hoffman, "and we immediately guessed, and we guessed right that these hair follicle stem cells are very similar to the brain stem cells."

Researchers have been looking at stem cells as a way help the body repair itself, even with injuries that are now often considered permanent, such as brain, spinal cord or nerve injuries. Embryonic stem cells have been shown to be very useful, but many object to their use on ethical grounds.

Research such as that done by Hoffman and his team is looking into adult stem cells. Hoffman says, "Perhaps we don't have to worry about embryonic stem cells or invasive procedures to get stem cells." Adding that only the hairs and the follicle would have to be removed. "Dermatologists can do this in seconds," he explains.

In their first experiments, they tried to, according to Hoffman, "convert the hair follicle stem cells into brain cells in the laboratory." When that worked, he says, "Then we knew there was a real relationship between the hair follicle stem cells and the brain stem cells." They then put them in mice, and found they still formed neurons.

From there they worked with mice with injured nerves. "We injected these hair follicle stem cells into the area where the nerve or the spinal cord is severed… [and] found that the nerve or spinal cord could be regenerated because we injected these hair follicle stem cells," says Hoffman.

He says they must still do a lot of testing, over several years, with mice before they'll be ready to see how this might apply to people.

This work was published in the December 6, 2005 issue of Proceedings of the National Academy of Sciences, and was funded by the National Institutes of Health.

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