Rats with spinal cord injuries regained the use of their limbs after receiving a new gene therapy which helps mend damaged nerves in the spine.
The new therapy works by inducing cells to produce an enzyme called chondroitinase which breaks down the thick scar tissue surrounding the site of injury, thereby allowing nerve cells to reconnect.
After two months on the therapy, mice regained enough control of their paws to be able to grab little sugar pellets from a raised platform.
“The gene therapy has enabled us to treat large areas of the spinal cord with only one injection,” said lead researcher on the study Elizabeth Bradbury from King’s College London.
“This is important because the spinal cord is long and the pathology spreads down its whole length after injury”, meaning that ambulatory control tends to decrease over time.
At this point, the therapy is still in its preliminary stages and will require quite a bit more testing in animal models before it can be rolled out to hospitals and health clinics.
The end goal of the research team behind the new discovery is to apply the gene therapy to people who had lost control of their upper limbs due to injury, preventing them from performing simple tasks.
“Recovering the use of the hands is the top priority for the majority of individuals living with spinal cord injuries. It would enable them to do everyday tasks such as washing and dressing independently, picking up a coffee cup, and would be life changing,” explained Bradbury.
In order to move on to clinical trials in humans, the researchers will have to prove the efficacy of the new therapy in larger animals, and develop a mechanism to completely shut it down once the desired effect has been achieved.
Although the expression of the gene is controlled by a ‘stealth gene switch’ triggered by a common antibiotic and invisible to the immune system, a small amount of chondroitinase was still being pumped out after the treatment was terminated.
“While we are hopeful, we know there is a long way to go to add further safety elements to the gene therapy before it can be used in humans,” concluded Bradbury.
The study was published in the journal Brain on 14 June 2018.