X-Message-Number: 11838 Date: Thu, 27 May 1999 21:29:47 -0400 From: Jan Coetzee <> Subject: re-growing spinal cord Researchers Regrow Severed Spinal Cords In Rats By Maggie Fox, Health and Science Correspondent WASHINGTON (Reuters) - Researchers said Thursday they had coaxed the severed spinal cords of rats into re-growing and said it may soon be possible to do the same in humans. The researchers, at Massachusetts General Hospital, said they still were not sure just how the cells were told to start growing. But when they damaged one branch of a nerve, it somehow signaled another branch to re-grow. ``We have actually tricked nerve cells into growing beyond the area of a spinal cord injury by switching them into an actively growing state,'' Dr. Clifford Woolf, who led the study, said in a statement. ``While the particular approach we used cannot be applied in humans, it points us in a promising new direction. The question is no longer whether spinal cord regeneration is possible but how it will be achieved.'' Most nerve cells re-grow when cut, but those in the spinal column are more stubborn. Researchers do not know why -- whether it is because a scar stops them from regenerating, or the chemicals that signal growth just cannot get through. Many teams of scientists have had varying success with physical bridges that bring severed spinal cord cells back together, or chemicals that instruct cells to grow. Others have tried immune cells injected into the injured area. Woolf's team took a different tack. Nerves, which are bundles of nerve cells, have two branches. The peripheral branch goes out into the body -- to the skin, the muscles, the joints and so on. Another branch consists of bundles of axons -- the long, thin strands that connect nerve cells -- stretching up the spinal cord and into the brain. The peripheral branches usually heal just fine, while the central branch often does not. Woolf's team worked with rats to see if the peripheral branch gets some kind of signal that the central branch does not. ``One possibility may be that when a peripheral neuron is damaged, it can still switch on the growth program but the central neuron may not be able to,'' he said in a telephone interview. In their rats they damaged the peripheral branch of the sciatic nerve, which is the main sensory nerve to the leg. At the same time they damaged the spinal cord. Writing in the journal Neuron, they said the results were striking, with numerous new axons growing around the damaged area of the spinal cord. They did not completely heal the break, however, so Woolf's team thought perhaps ``priming'' the nerve might help. They first damaged the peripheral branch, waited a week, and then cut the spinal cord. This really worked. ``It primed the cell into a growth state, so that at the time it was injured it was ready to grow. We got growth that spanned the injured site,'' Woolf said. ``We have shown that if we can switch these cells into a state where they can grow, they will grow -- even the central branch.'' Obviously such a thing could not be tested in humans as it would be unethical to deliberately injure a human's spinal cord. But if the signaling chemicals involved could be identified, it might be possible to use them to treat a spinal cord injury. ``Once we figure it out we should be apply to apply this to humans,'' Woolf said. Woolf thinks there might be a window of opportunity of about a week during which growth could be induced. ``The trigger might be a growth factor that switches on a whole broad range of proteins that allow the cell to grow,'' he said. The Spinal Cord Injury Association says between 10,000 and 12,000 people in the United States suffer from traumatic spinal cord injuries every year. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11838