June 1, 2012

Paralyzed Rats Encouraged To Walk And Run In Lab Study

Swiss scientists on Thursday said they have given paralyzed rats the ability to walk again through a combination of spinal cord stimulation and robotic therapy.

The team of researchers, led by Gregoire Courtine at Ecole Polytechnique Federale de Lausanne, were able to get severely paralyzed rats walking and even running again within a couple of weeks following therapy. They effectively engaged the rats in participating in their own rehabilitation.

Publishing the research findings from a five-year study in the journal Science, Courtine said: “Our rats are not only voluntarily initiating a walking gait, but they are soon sprinting, climbing up stairs and avoiding obstacles.”
Courtine and colleagues found a massive three-fold increase in the connections between the brain and spinal cord after training exercises.

“The motor cortex developed new pathways to regain control of the area below the injury. This was really fascinating to see,” Courtine told AFP. “What we observed was this extensive reorganization of the central nervous system not only at the level of the injury but throughout the brain, brain stem and spinal cord.”

The therapy combined an electrical-chemical stimulation of the spinal cord, mimicking the signals the brain would normally send to limbs to produce movement, and a robotic device that allowed the rats to remain upright.

The robotic device kept the rats in a two-legged standing position and stabilized them from teetering sideways, but did not aid in forward movement.

The team used a chocolate reward as incentive for the specimens to become motivated and try to reach the edible goal. Soon, the animals succeeded in making a few steps. Within five to six weeks, as their skills improved, the rats were climbing stairs, dodging obstacles, and even running without any treat in view.

“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. He noted that some show more improvement than others.

Courtine pointed out that while the research is significant, it remains unclear whether similar techniques could help people with spinal cord damage, but he added that the technique does hint a new ways of treating paralysis.

Elizabeth Bradbury, a Medical Research Council senior fellow at King´s College London, agrees.

“This is ground-breaking research and offers great hope for the future of restoring function to spinal injured patients,” said Bradbury.

However, she noted that very few human spinal cord injuries are the result of a direct cut through the cord, as seen in the rat experiments. Human injuries are most often the result of bruising or compression and its unclear whether the technique would work in these type of injuries. It is also unclear if this type of therapy could help a patient who has had a long-term spinal cord injury, as scar tissue, holes and dead and degenerated nerve cells and fibers have occurred.

Nevertheless, Courtine´s study is an encouraging step in the right direction, demonstrating the ability of the spinal cord to repair itself, something known as neuroplasticity.

Other attempts have also been made to repair spinal cords, including the use of stem cell therapy. However, Geron, the world´s leading embryonic stem cell company, which pioneered work in that field, halted its operations last year.

Courtine and others at EPFL are in the beginning stages of developing an $11.1 million project, called NeuWalk, aiming to design a fully operative spinal neuroprosthetics system for humans.

“We are not thinking this will cure spinal cord injury. We need to be very clear on this. This is not a cure,” Courtine said. “What we observed in rats -- the plasticity and the extent of the recovery is very surprising -- so now we need to optimize all these systems for humans and do our best to at least improve functional recovery.”

Norman Saunders, a neuroscientist at the University of Melbourne in Australia, told Reuters in an emailed statement that although it remains to be seen whether the technique can be translated to people, “it looks more promising than previously proposed treatments for spinal cord injury.”

This study “suggests we are on the edge of a truly profound advance in modern medicine: the prospect of repairing the spinal cord after injury,” added Bryce Vissel, head of the Neurodegenerative Diseases Research Laboratory at the Garvan Institute of Medical Research in Sydney.

Courtine hopes to begin human trials within a year or two at Balgrist University Hospital Spinal Cord Injury Center in Zurich.