Montreal researchers ready for spinal cord injury clinical trials

Montreal researchers at the forefront of work in the field have developed an interface that enables an animal with paralyzed hind legs to walk again by alternately stimulating the two hemispheres of its brain.

These pre-clinical trials were conducted on what the researchers call a "large animal model" that is much more human-like than mice. Their results are so conclusive that they are now ready to move on to clinical trials in a few years' time.

"We're going to stimulate the left and right cortex alternately so as to recover movement in both legs," explained Marina Martinez, who is a regular researcher at the Hôpital du Sacré-Cœur-de-Montréal and a professor in the neuroscience department at the Université de Montréal.

"As soon as we start alternating stimulation in the brain, the animal will immediately start walking again."

Martinez's team is the only one in the world to be working on such a strategy, with the potential of one day enabling paraplegics to walk again. Their most recent work was published by ScienceDirect.

The researchers previously tested the same approach on mice with injuries less similar to those found in humans.

This time, they used larger animals and wounds very similar to human ones.

In the first study, a single cortex was stimulated with electrodes to relieve paralysis in just one of the mice's legs. This time, both cortices were stimulated alternately to restore movement to the two paralyzed legs of a larger animal, which is similar to a human paraplegic.

"When you walk, you alternate the movements of your two legs, and that's what we wanted to do with this technique, and that's what we succeeded in doing in this animal model," explained Martinez.

The technologies used are also much more similar to what could eventually be implemented in humans, which should facilitate the transfer of knowledge.

"We've really reached a higher stage," said Martinez. "With the rat, we had a proof of concept. Now we're at a very clinical stage."

The technology that she and her colleagues are working on applies only to incomplete spinal cord injuries.

They are trying to reproduce normal brain activity to give the spinal cord back the instructions it should naturally receive during walking, which implies that certain nerve fibres still connect the brain to the lower body.

"While this technology will never be able to be applied to complete spinal cord injuries," Martinez said, "each step gives us this opportunity to get a little closer to humans.

"The ultimate goal of our team is really to help patients and those in need. That's why we work, it's really for them, that's our main motivation," she said.

This report by The Canadian Press was first published in French on July 16, 2023.