European researchers said Thursday they have found a way to help paralyzed rats learn to walk again through a combination of spinal cord stimulation and robotic-aided therapy.
The rats also showed massive four-fold increase in the connections between the brain and spinal cord after training, according to the research by scientists in Switzerland, published in the U.S journal Science.
The key to the success of the therapy was how it engaged the rats to participate in their own rehabilitation, said lead author Gregoire Courtine, chair of the International Paraplegic Foundation in Spinal Cord Repair at the Ecole Polytechnique Federale de Lausanne.
"In the beginning... the animal is struggling and it is really difficult," he told AFP.
"Then the first time it happens, the animal is surprised. It looks at you like, 'Wow. I walked!'"
The therapy combines an electrical-chemical stimulation of the spinal cord, mimicking the signals the brain would normally send to initiate movement in the limbs, and a rehabilitation device that helps the rats stand upright.
The rats were hoisted into a two-legged standing position with a robotic harness that did not propel them forward but stabilized them if they tottered sideways, so they could try to walk without falling.
A chocolate reward was placed in front of the rats. Soon, the animals succeeded in making a few steps. And within two to three weeks, as their skills improved, the rats were voluntarily climbing stairs, dodging obstacle courses and even sprinting.
"We had a very high percentage of success with these animals. We always observed, in all of the animals we treated, recovery of voluntary movement," said Courtine, adding that more than 100 lab rats were tested.
"In some animals it was weak, in some animals it was spectacular."
A similar therapy has been tried in one human subject, an American in his 20s named Rob Summers who was paralyzed from the chest down in a car wreck, and was described in an article in British journal The Lancet last year.
That case study provided first proof that such therapies may help restore voluntary movement in humans.
Courtine said he hopes to begin trials in humans using his team's technique in the next couple of years.