Enzyme Promotes Nerve Regrowth in Rats

NEW YORK (Reuters Health) - British researchers may have found a way to help damaged nerves in the brain and spinal cord grow back to their original state, a finding that helps lay the groundwork for treating human spinal cord injuries.

After injury to the brain or spinal cord, scar tissue develops that prevents nerves from growing back. Researchers already knew that the scar tissue contained proteins that prevented regrowth. Now researchers led by Dr. James Fawcett of the University of Cambridge, UK, have found that inhibiting the action of these proteins can encourage nerves to grow back.

According to Fawcett, there are three main reasons that nerves have a difficult time growing back: the nerves themselves do not grow well; the cells that insulate the nerves make molecules that prevent the regrowth of nerves; and scar tissue, which forms after injury, also contains molecules that block regrowth.

"Treatments that address the first two reasons have been developed,'' Fawcett told Reuters Health. "Our experiments demonstrate a treatment that addresses the third reason, the inhibitory molecules in scar tissue.''

Reporting in the May issue of Nature Neuroscience, Fawcett's team conducted the experiments in anesthetized rats by damaging nerves within the brain. They then gave the rats an enzyme that blocked the formation of the inhibitory scar tissue molecules and looked to see whether the damaged nerves would grow back.

The nerves did grow back. Not only that, but they grew back along the course of their original location, which could mean that the nerves' original function might be restored.

"Although there is still no treatment for spinal cord injury, there are now several methods to promote nerve fiber regeneration that have been successful in animal models,'' Fawcett said. "The amount of regeneration in these various experiments--up to four centimeters--is sufficient to bring a useful return of function to a patient with a spinal cord injury, although not complete recovery,'' he added.

"Efforts to apply these techniques to human patients are starting, but the clinical assessment methods that will have to be in place before a trial begins will take another four years to put in place,'' Fawcett said.

But he added that "the basic science of nerve fiber regeneration is making rapid progress, and a partial cure for spinal injury is now a real possibility.''

SOURCE: Nature Neuroscience 2001;4:465-466.