Stem Cell Treatments for Paralysis

One of the first stem cell treatments to be investigated was for victims of paralysis due to spinal cord injury. The late Christopher Reeve raised awareness of the potential of stem cells to treat paralysis. According to the Christopher and Dana Reeve Foundation, up to 400,000 Americans have some degree of paralysis due to spinal cord injury; many more people suffer from paralysis around the world. Both embryonic stem cells and adult stem cells have been studied for paralysis treatment.

Researchers at the University of California at Irvine developed a successful method of using embryonic stem cells to treat paralyzed rats. The researchers were able to inject the stem cells into the spinal cords of rats that were paralyzed by spinal cord injury. The stem cells then developed into neurons called oligodendrites that produce a substance called myelin. Myelin is stripped away in certain spinal cord injuries, but the new oligodendrites replaced the missed myelin. As a result, nerve impulses could once again travel through the damaged area, and the rats regained the ability to walk.

In January 2009, the U.S. Food & Drug Administration approved a clinical trial of this treatment on humans. Geron Corporation, based in Menlo Park, California, will conduct the trial.

In Spain, researchers were recently successful in achieving a similar success in rats using adult stem cells. The rats had paralysis due to severe spinal cord injury. The stem cells were obtained not from embryos, but from the lining of the rats' own spinal cords. One week after injection of these stem cells into the injured area, the rats regained a significant amount of motor function. Researchers found that the injured spinal tissue "recruited" the stem cells. The stem cells multiplied 10 times faster in the rats with spinal injuries than in healthy, uninjured control rats.

Unlike human embryonic stem cell treatment for paralysis, adult stem cell treatment is not yet available for clinical trials in humans.

The research boils down to a few facts:

• There is still no currently available treatment to regenerate damaged spinal cord tissue.
• The Geron trial may result in the first such treatment.
• The Geron treatment is controversial in the stem cell debate because it uses embryonic stem cells.
• Adult stem cells may eventually be used to treat paralysis, but no trials are underway.
• An adult stem cell treatment for paralysis, if it existed, would not be controversial in the stem cell debate.

• "UCI behind world's first embryonic stem cell study in humans." University of California at Irvine Press Release.
• "Study: Stem Cells Reverse Paralysis in Rats." LiveScience.com.