Purdue News

June 9, 1986 Spinal Nerves Regenerate Around Cut in Cord West Lafayette, Ind. – Purdue University researchers have induced damaged spinal-cord nerves of guinea pigs to regenerate and bridge the severed portions of their spines. In research to be reported in August in the Journal of Comparative Neurology, a team led by Professor Richard Borgens used electrodes implanted in the guinea pigs to cause the damaged neurons not only to regenerate but also to return to their normal location on the other side of the spinal injury. Dr. Charles Carson of Fergus Falls, Minn., president of the Spinal Cord Society and himself a paraplegic, termed the accomplishment "an extraordinary achievement...the first time this method has been successfully applied to the adult mammalian spinal cord." "It's remarkable," Carson said, "because we have perhaps hit on a way to solve at least part of the (paralysis) problem and, better yet, to do it non-invasively." He noted that nearly one-half million Americans are either paraplegics or quadriplegics and that an additional one million or so have spinal problems with less severe paralysis. He said there are between 10,000 and 20,000 new cases a year, mostly from auto accidents. In Borgens' approach, the spinal cord itself is not disturbed. Borgens explained that by placing a weak electric field across the cut cord, severed fibers in the cord begin to regenerate and grow, detouring around obstacles such as small blood vessels and scar tissue. "The crowning feature of this," he said, "is that the fibers induced to grow by this method regenerate around the damaged area and return to a nearly normal configuration." Borgens added that in his experiments, the guinea pigs' damaged neurons continued to grow in this manner even after the electric field was removed. He pointed out that while several other techniques have been developed which demonstrate that fibers of the brain and spinal cord can be induced to regenerate fairly long distances, none has been shown to induce regeneration over sufficiently long spans or in the fibers' normal arrangement. He observed that one of the other techniques, implantation of what's called a peripheral nerve bridge, requires surgical manipulation of the cord itself and "has failed to show that fibers that grow into these 'bridges' ever re-enter the normal environment of the spinal cord or the brain." Borgens, an associate professor of developmental anatomy in the Purdue veterinary medical school, said that although the neurons of the guinea pigs used in the Purdue experiments had regenerated across the damaged spinal areas, no testing had yet been carried out to determine whether function itself had returned. Experiments designed to test whether function will accompany the nerve regeneration are under way, he said. "The significance of achieving this nerve regeneration in guinea pigs," said Borgens, "is that it's another step up on the mammalian spinal-cord ladder." Borgens earlier showed that spinal-cord nerve regeneration in larval lampreys--one of the few vertebrates which can naturally regenerate neural function across a severed spinal cord--occurred about three times faster when an electric field was imposed across the cut. The next step prior to clinical testing in humans, Borgens said, would be to use the procedure on dogs. "We believe," Borgens remarked, "that these findings bear great promise for eventual use in medical therapy dealing with traumatic injury to the human spinal cord--perhaps the brain as well. Our continuing efforts will be geared to test if this can lead to functional recovery not only in recent injuries but also in chronic or long-standing injuries to the spinal cord." Pioneering spinal-cord work by Borgens was seeded by the Spinal Cord Society. Current studies by Borgens and his collaborator, Dr. Andrew Blight of the New York University Medical Center in Manhattan, are funded by the society as well as by the Department of Defense and the U.S. Public Health Service. Purdue News Service: (765) 494-2096; purduenews@purdue.edu To the Purdue News and Photos Page