A new study has identified a subset of neurons that is activated and remodelled by spinal cord electrical stimulation, allowing paralysed patients to stand up, walk, and rebuild their muscles through therapy. This discovery may lead to better therapy methods which can improve the quality of life of such patients, reported the ScienceAlert.
This discovery, made in nine patients, is a significant clinical breakthrough. The study was published on November 9 in the journal, Nature. The study was carried out by researchers of the Swiss research group NeuroRestore, who used mice as a starting point to identify the exact nerve groups stimulated by the therapy.
What is spinal cord electrical stimulation?
Paralysis happens when the circuitry that allows people to control various parts of their body is cut off. However, some connections remain. These connections are then zapped with electricity — via surgical implants of a bundle of electrodes placed into the lower spinal cord. This method is called epidural electrical stimulation. This along with therapy helped people regain control of their body parts.
While neither doctors nor scientists were clear on why or how the approach works, the new study claims to have answered the question.
How does it work?
In the study, neuroscientists at the Swiss Federal Institute of Technology tracked nine spinal paralysis patients through a five-month programme of electrical stimulation, exercise, and rehab. It was found that with electrical stimulation, all nine patients eventually regained their ability to walk unassisted.
The team then obtained images depicting nerve cell activity in the spinal cord of the patients while walking, both before and after undergoing treatment. It was found that the spinal cords of these individuals showed less activity than before, which indicated that perhaps only a subset of neurons was being activated during electrical stimulation, which helped the patients recover.
Thus, to understand this better, the team repeated the study on mice whose spinal cords had been injured. At different points of therapy, as those mice walked on a treadmill with support and electrical stimulation, the researchers determined which genes are activated in specific populations of nerve cells across the spinal cord.
A diagram was created based on these cells’ locations. The team then used a computer program to determine which nerve cell populations were activated during the recovery process. It was found that a specific subpopulation of neurons in the mouse spinal cord, which express two markers called Vsx2 and Hoxa10, was activated after electrical stimulation, which helped the mice recover.
To verify the results, researchers selectively manipulated the activity of these neurons in mice. They found that when these neurons were activated, the mice recovered their ability to walk; when they were blocked, the mice did not recover. Thus suggesting that these cells are crucial for recovery after spinal cord injury.
However, this study is just the first step and many questions still need to be answered before epidural electrical stimulation can be labelled as a go-to therapy for spinal cord patients, science.org reported.
