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Stem cells help heal paralyzed rats

From Elizabeth Cohen
CNN Medical Unit

ATLANTA, Georgia (CNN) -- A paraplegic rat may be the key to helping Dr. John McDonald get his patient, Christopher Reeve, walking again.

The actor was paralyzed from the neck down when he was thrown from a horse in 1995.

McDonald, director of the Spinal Cord Injury Unit at Washington University School of Medicine in St. Louis, Missouri, gave rats a similar injury, then injected some with stem cells. Six weeks later, their hind legs functioned again.

So when can Reeve get this treatment?

Learn more about stem cells from the National Institutes of Health  

It hasn't made it past the rat stage, because to get these stem cells from human beings, you have to destroy a human embryo. And some people are vehemently fighting the research.

That infuriates Reeve, who has seen what stem cells can do for rats.

"Never before has there been such a powerful tool, such a resource that can give so much hope. And to have it just sitting here right in front of us, ready to go while all this debate rages on, is really, really frustrating," he said.

Human embryos destroyed

Christopher Reeve
Christopher Reeve hopes embryonic stem cell research will allow him to walk again  

When Reeve fell, he injured the area around the top two vertebrae in his spine. The injury caused a cyst to grow inside the spinal cord, and as the cyst grew, it damaged what's called the myelin coating around part of the nerve cells in his spine.

Without that coating, the nerves can't work properly, and Reeve can't move.

"If you can imagine a wire with a rubber coating around it, that rubber coating allows conductivity, and if you take it away, the wire doesn't work," he said.

That's where the embryonic stem cells come in. They're blank cells that can be turned into basically any type of tissue.

In the case of the rats, doctors turned the stem cells into myelin coating cells and injected them into the rats. The coating grew back where it was needed, and the rats could move their hind legs again.

For this to work in people, scientists would have to destroy a human embryo to get the stem cells. There are about 100,000 embryos stored in freezers in infertility clinics nationwide that parents don't want to use anymore.

People opposed to destroying embryos want to find some other way of finding stem cells. But Reeve says that could take years -- years that he'll spend in a wheelchair. And since his injury is causing premature aging, they're years he says he might not have.

• Washington University School of Medicine
• Stem Cells: The International Journal of Cell Differentiation and Proliferation

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