Traditionally, physicians have believed that spinal cord injuries are irreversible. Paralysis will never go away and the best patients can hope for is to learn new ways of coping with the world. Now, advances in neuroscience are changing that view. Although researchers say tangible results are still years away, there is evidence that recovery from spinal cord injuries is possible.
“Ten years ago I would not have used the word ‘cure’,” said Stephen G. Waxman, M.D., Ph.D., professor and chair of the department of neurology at the medical school. “Now it is a realistic objective.” Research has found that some viable nerve fibers may survive accidents that appear to sever the spinal cord. “We are taking several approaches to repairing those fibers,” Waxman said, “including transplantation of myelin-forming cells.”
Two initiatives involving Yale researchers are pursuing that goal. One is the PVA/EPVA Neuroscience and Regeneration Research Center at the Veterans Affairs Connecticut Healthcare System in West Haven, which Waxman directs. In September the center celebrated the opening of six new research labs. The Phil N. Allen and Mayreta V. Allen Laboratories for Multiple Sclerosis Research will seek new therapies and cures for spinal cord injuries, multiple sclerosis and related disorders through studies of molecular biology, electrophysiology, pharmacology, computer modeling and image analysis. Construction of the laboratories was supported by gifts from the Eastern Paralyzed Veterans Association and the Phil N. Allen Charitable Trust.
In addition, the National Institutes of Health awarded Yale researchers a $4.5-million grant to continue their studies of olfactory ensheathing cells, which may regenerate nerves when implanted in the spinal cord.
Experiments in vitro and in vivo have shown that olfactory ensheathing cells implanted at the site of spinal cord injuries stimulate the regrowth of myelin, the spinal cord’s insulation, and axons, long bundles of nerves that transmit information. “In many cases spinal cord injuries are so devastating that the patients have nothing to lose,” said Charles A. Greer, Ph.D., professor of neurosurgery and principal investigator on the project. “They are not going to get better without some sort of dramatic intervention. This is a dramatic intervention.”
Unlike other cells in the nervous system, olfactory ensheathing cells can regenerate. Part of the pathway that transmits information about odor to the brain, they are the only nervous system cells exposed to the environment, and their ability to regenerate serves as a protective mechanism against everyday toxins and irritants such as cigarette smoke. Greer and his colleagues found that implanting these cells helps axons overcome an “impenetrable brick wall” of glial scar tissue that forms when spinal cords are injured. “We think that the ensheathing cells form a supportive network, in some way that as yet we don’t understand, that helps the axons get through that brick wall,” he said.
His co-investigators are Jeffery D. Kocsis, Ph.D., professor of neurology and a senior investigator of the PVA/EPVA Research Center, and Anthony N. van den Pol, Ph.D., professor of research neurosurgery.