Nine patients paralyzed by a spinal cord injury that underwent selective epidural electrical stimulation of the area that controls the movement of the legs regained some motor function, which made it possible to identify the neurons that get back on track.
The study that publishes Nature conducted by the Swiss research center NeuroRestore improves understanding of How can mobility be restored after paralysis?
The team led by Gregorie Corutine and Jocelyne Bloch not only demonstrated the efficacy of this therapy, but also that the improvement in motor function was maintained in the patients once the treatment process was completed. neurorehabilitation and when electrical stimulation was turned off.
Electrical stimulation of the spinal cord has been effective in improving gait recovery in people with paralysis, but the underlying mechanism of this treatment remains unclear.
In this studio, nine individuals with severe or complete paralysis caused by spinal cord injury were enrolled in a clinical trial and received epidural electrical stimulation (EES) treatment.
All immediately recovered or improved their ability to walk during treatment and showed improvements in mobility after five months of treatment and rehabilitation with EES.
New research has identified the type of neuron that is activated and remodeled by stimulation of the spinal cord, allowing patients to stand up, walk and rebuild their muscles, thus improving their quality of life, a discovery that represents a fundamental clinical advance, NeuroRestore noted.
The results suggested that the nerve fibers used for walking had been rearranged and scientists felt it was crucial to understand exactly how this neuronal reorganization occurs in order to develop more effective treatments and improve the lives of as many patients as possible.
The team first studied the underlying mechanisms in mice, revealing a surprising property in a family of neurons that express the gene Vsx2.
While these neurons were not necessary for walking in healthy mice, they were essential for recovery of motor function after a spinal cord injury.
Scientists were able, for the first time, to see the activity of a patient’s spinal cord while he was walking, leading to an unexpected finding: during the process of spinal cord stimulation, neuronal activity decreased during walking.
Thus, they hypothesized that it was because neuronal activity was selectively directed at recovery of motor function.
To test their hypothesis, they developed advanced molecular technology to establish the first 3D molecular mapping of the spinal cordwhich allowed them to observe the recovery process at the level of neurons, Corutine explained.
The discovery was that stimulation of the spinal cord activates Vsx2 neurons, which become increasingly important as the child develops. the reorganization process.
The team validated their findings with epidural implants that were retrofitted by adding light-emitting diodes, which allowed the system to not only stimulate the spinal cord, but also turn off Vsx2 neurons on their own by an optogenetic process.
When the system was used on mice with spinal cord injury, they immediately stopped walking as a result of neuron deactivation, but there was no effect on mice. healthy mice.
This implies, according to the team, that Vsx2 neurons are necessary and sufficient for spinal cord stimulation therapies to be effective and lead to neuronal reorganization.
“It is essential for neuroscientists to be able to understand the specific role that each neuronal subpopulation plays in a complex activity such as walking”Bloch said.
“Our new study, in which nine patients from clinical trials were able to recover a certain degree of motor function thanks to our implants, is providing us with valuable information on the process of reorganization of neurons in the spinal cord.”