Early research in spinal cord injuries in mice treated with gene therapies suggests that doctors may one day be able to reverse some paralysis in human beings.
A breakthrough in how mice recover from spinal injuries has been made by scientists at the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland who looked at how neurons – the body's message-sending nerve cells – respond during recovery.
Researchers studied partially damaged spinal cords of mice to learn more about the spontaneous recovery of motor function that follows an initial paralysis, because the reasons why some nerve fibres recover better than others are still not fully understood.
Experts looked at how single-cell nuclear RNA sequencing could promote regeneration of nerve fibres to identify which neurons were involved in natural spinal-cord repair.
"Five years ago, we demonstrated that nerve fibres can be regenerated across anatomically complete spinal cord injuries," said Mark Anderson, a senior author of the study, and director of Central Nervous System Regeneration at the Wyss Centre for Bio and Neuroengineering.
"But we also realised this wasn't enough to restore motor function, because the new fibres failed to connect to the right places on the other side of the lesion.”
By activating growth programmes in the neutrons identified as most likely to fuel regeneration, scientists were able to develop a gene therapy to stimulate recovery.
Regaining the ability to walk
The therapy allowed mice with anatomically complete spinal cord injuries to regain a walking ability, albeit with a restricted gait similar to mice with partial injuries.
When combined with existing therapies such as electrical stimulation of the spinal cord, it is hoped a wider range of movement could develop.
The team of Swiss researchers shared their findings with experts from UCLA and Harvard Medical School in the US to see how this kind of gene therapy could one day be applied to spinal injuries in humans.
While there is no cure to reverse every type of paralysis, some therapies have recorded success in regaining feeling and movement in some body parts.
Brain implants paired with a spinal receiver were recently successful in allowing those with paralysis from an injury to regain movement.
According to the World Health Organisation, about 250,000 to 500,000 spinal cord injuries occur globally each year.
Researchers at EPFL said more work was needed to see how the gene therapies could be effective in humans.
"We believe a complete solution for treating spinal cord injury will require both approaches – gene therapy to regrow relevant nerve fibres, and spinal stimulation to maximise the ability of both these fibres and the spinal cord below the injury to produce movement,” said Gregoire Courtine, a senior author of the study.