Pharmacy Daily | Walking after spinal injury

SWISS researchers are giving hope to the sufferers of spinal cord injury, following their breakthrough in “waking-up” the “spinal brain” of rats with spinal cord injuries. Published in Science, the study involved rats with spinal cord injuries and severe paralysis and found that a severed section of the spinal cord is able to make a comeback when its own innate intelligence and regenerative capacity, or what study lead author Grégoire Courtine calls the “spinal brain”, is awakened. “After a couple of weeks of neurorehabilitation with a combination of a robotic harness and electricalchemical stimulation, our rats are not only voluntarily initiating a walking gait, but they are soon sprinting, climbing up stairs and avoiding obstacles,” Courtine said. During the research the rats were injected with a chemical solution of monoamine agonists to trigger cell responses by binding to specific dopamine, adrenaline, and serotonin receptors on the spinal neurons. This chemical mix replaced neurotransmitters released by brainstem pathways in healthy subjects, and excited neurons readying them to coordinate lower body movement. Shortly after the injection, the rats’ spinal cords were stimulated electronically. “This localised epidural stimulation sent continuous electrical signals through nerve fibers to the chemically excited neurons that control leg movement,” said researcher Rubia van den Brand. “All that is left was to initiate that movement,” Brand added. The research found that the stimulated spinal column, physically isolated from the brain from the lesion down, started taking over the task of modulating leg movement, allowing previously paralyzed rats to walk involuntarily over treadmills. According to the researchers, these experiments revealed that the movement of the treadmill created sensory feedback that initiated walking: the spinal brain took over, and walking essentially occurred without any input from the rat’s actual brain. From here, researchers replaced the treadmill with a robotic device that supported the subjects and only came into play when they lost balance, giving them the impression of having a healthy and working spinal column, which in turn encouraged them to will themselves toward a chocolate reward on the other end of the platform. “What they deemed will powerbased training translated into a fourfold increase in nerve fibers throughout the brain and spine—a regrowth that proves the tremendous potential for neuroplasticity even after severe central nervous system injury,” said researcher Janine Heutschi. The researchers then found that the newly formed fibers bypassed the original spinal lesion and allowed signals from the brain to reach the spine, and that the signal was sufficiently strong to initiate movement over ground, without the treadmill, meaning the rats began to walk voluntarily towards the reward, entirely supporting their own weight. “This is the world-cup of neurorehabilitation,” said Courtine. “Our rats have become athletes when just weeks before they were completely paralyzed. “I am talking about 100% recuperation of voluntary movement,” he added.

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