Major Advances in Spinal Cord Repair Reported
Major advances in healing damaged spines, the most important cause of paralysis, were reported Wednesday by two independent research groups.
One group used fetal cell transplants to restore near-normal function in the rear legs of cats that had suffered paralyzing spinal damage, apparently the first report of such success in any mammal. In a less successful experiment, the second group used a new surgical technique, along with growth-promoting chemicals, to restore partial function in two such cats.
The fetal cell results come at a particularly compelling time in Washington because Congress is again trying to overturn or modify the Bush Administration’s ban on the use of human fetal cells in government-funded research. The report is likely to provide fresh ammunition for opponents of the ban.
Although the new techniques and growth-promoting chemicals did not work in all the animals treated, one of the groups, at Boston University School of Medicine, has already attempted a simplified form of the surgical procedure in six human patients. The researchers said it is too early to report the human results.
About 10,000 cases of severe spinal cord injuries occur each year in the United States and 250,000 Americans suffer from paralysis as a result of such injuries.
While the studies obviously need to be repeated and confirmed, “both studies are very promising,” said Dr. Michael Walker, a neuroscientist at the National Institute of Neurological Disorders and Stroke.
“I think the major message from these studies is that regeneration of the spinal cord is possible. It’s no longer a matter of ‘if,’ but simply a matter of time and effort,” added Dr. Wise Young, a neuroscientist at the New York University Medical Center.
The researchers cautioned against excessive optimism.
“People studying spinal cord injuries in the past have gotten very optimistic and made (unjustified) predictions, when the fact is nobody has a crystal ball,” said Dr. Paul J. Reier, a neuroscientist at the Veterans Affairs Medical Center in Cincinnati, co-author of one of the reports. “But we’re working on the same types of models where people have said there was no hope and we’re seeing hints that maybe something can be done to improve function.”
Dr. Douglas K. Anderson, a neuroscientist at the University of Florida College of Medicine, added: “We have some very interesting preliminary data that correlates with improvement of function in these grafts. There are certain experiments that would prove it more conclusively. We’re doing them now.”
The Boston University study is reported in the September issue of the journal Brain Research, while Reier and Anderson presented their results Wednesday at a meeting of the American Paralysis Assn. in New Jersey.
Reier and Anderson compressed the spinal cords of 15 adult cats, leaving them partially or completely paralyzed. Two to 10 weeks later they treated the animals by implanting cats’ fetal brain or spinal cord cells next to the spinal cords.
Eight of the animals regained “near-normal” walking ability after the operations, Reier said. In one of the most dramatic cases, a totally paralyzed cat’s activity after the surgery was “almost acrobatic,” he said. It could climb stairs and change gaits with only minor hesitation and wobbling. And when he squeezes the affected area, the cats look around and try to pull away, Reier said, indicating some recovery of sensory function as well.
“I went out to the university to examine the cats,” Young said, “and they are actually walking, there is no mistake about that.”
Three of the other cats showed no recovery of function, however, and two showed only minimal recovery. The fetal tissue was rejected in the last two. These failures suggest that there is much to be learned. “We’re a long way from having a method that can be applied in human medicine,” Reier said.
In contrast, Dr. Harry S. Goldsmith, a surgeon at Boston University, and Dr. Jack C. de la Torre, a neurosurgeon at the University of Ottawa, severed the spinal cords of 10 cats, two of whom were not treated.
They treated the eight remaining cats with a surgical procedure in which a “scaffolding” of cartilage was inserted into the gap in the spinal cord and the entire damaged area enfolded in a flap of abdominal tissue called the omentum, which normally separates the stomach from the colon. The precise role of the omentum in human physiology is unknown, Goldsmith said, but it is a rich source of biological factors that promote growth of blood vessels and neural tissues. They also administered growth-promoting chemicals to the spinal cords.
Two of the eight animals recovered partial function--they could walk if the researchers held them up by their tails. The two cats that responded were the only ones that received either of two chemicals, a natural growth promoter called laminin, or a synthetic chemical called 4-aminopyridine. The other six received other chemicals and did not respond.
Even though only two of eight showed improvement--and only modest improvement at that--Goldsmith said the results were important because before the two new reports no one had ever reported any improvement in experiments with mammals.
Outside observers were less optimistic about the results than Goldsmith is. “I frankly don’t think the neurological recovery was very impressive,” Young said. “Many injured cats can learn to walk with their tails held. But the results are exciting and should be pursued.”
Although Young said he thinks it is premature to test the procedure on humans, Goldstein reported that he and several investigators outside the United States have already performed a simplified version of the technique in humans. In these cases, the omentum is simply wrapped around the spinal cord in the hope that the omentum’s stimulating chemicals can provoke some regeneration.
At meetings, Goldsmith has reported improvement in some of the patients, although even he concedes that those reports are only anecdotal.
“That’s why we need a good, controlled trial of the technique in this country, and that’s what we are doing now,” he said. “The patients are very carefully studied before and after the procedure so that we can document any improvement.” He hopes to present preliminary results from the study after the first of the year.
But Young and Walker cautioned that the omentum transplant is a major operation in which the patient’s abdominal cavity must be opened in both the front and rear to complete it.
