Rats paralyzed by spinal cord injuries walked and ran after nerve-stimulating chemicals combined with electricity helped restore movement, according to a study that may provide clues to rehabilitating injured humans.
The therapy helped stimulate new connections in the spinal cord and brain, allowing nerve signals to reroute around the site of the injury, said study author Gregoire Courtine, an associate professor at Ecole Polytechnique Federale de Lausanne in Switzerland. The study was published yesterday in the journal Science.
The research demonstrates that new connections can be formed to the brain and it’s possible to do this through rehabilitation therapy, said V. Reggie Edgerton, a specialist in spinal control at the University of California, Los Angeles, who last year helped a paraplegic man named Rob Summers stand for the first time with the aid of an electronic stimulus device.
“I know there’s some controversy about whether rehabilitation even helps, but this shows very clearly that without rehab, you’re not going to get recovery,” Edgerton said in a telephone interview.
The caveat is that the lesion that caused the paralysis in the rats isn’t a common spinal cord injury in humans, Edgerton said. The trauma to the rats was less severe, he said.
The researchers injected the animals with chemicals that the body uses to spur nerve growth and simulated neurons firing with electrical stimulation, priming the cells to make new connections, according to the paper. Then the scientists attached the rats to a robot system that held them on their hind legs to help them regain walking ability. After a few weeks of training, they began to step on their own toward chocolate treats.
The system was meant to simulate balance, Courtine said. The device required the rats to push forward to move. After a few more weeks, the rats were able to support their full body weight on the hind legs, stepping up stairs to chase the chocolate.
“This isn’t a cure for spinal cord injury,” Courtine said. “It’s not a full recovery, and it only works when we provide stimulation.”
Another set of rats, similarly paralyzed and treated, were put on treadmills without the special robot. Those rats moved their hind legs automatically when the forelegs moved on the treadmill. They weren’t able to move on solid ground, as the other animals did, the paper said.
Summers, the man who stood with the aid of a Medtronic Inc. (MDT:US) device developed to control pain, was paralyzed from the chest down, though he had feeling in his legs. Like the mice, he was supported by a harness as he took steps on a treadmill. Courtine believes new nerve connections grew to enable voluntary movement.
Courtine plans to begin human trials with his method in Zurich in the next two years, he said.
“There is so much despair in spinal cord injured people, you don’t want to raise exaggerated hopes,” he said. “But we hope to test this as best we can.”
The work was funded by the European Research Council, the International Paraplegic Foundation, the Swiss National Science Foundation, and others.
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