Scientists have found a way to use gene therapy to treat rats with spinal cord injuries. Researchers are hopeful that their work could help people with paralysis resulting from a spinal injury to regain the ability to perform daily tasks.
In a new study, a team of scientists at Kings College London used rats with spinal injuries closely resembling human spinal injuries caused by traumatic impact, which can occur during events like car crashes or falls. These injuries typically occur around the neck and impact both the arms and legs.
After a traumatic spinal injury, dense scar tissue develops and prevents the formation of new connections between nerve cells. As a result, people who have suffered a spinal cord injury often lose the ability to perform everyday tasks including brushing their teeth, writing or holding a drink.
Scientists used a type of gene therapy that makes cells produce chondroitinase, an enzyme that is capable of breaking down scar tissue. As the scar tissue breaks down, nerve cell networks are able to grow again and muscle movement begins to be restored.
The team injected rats’ spinal cords with a gene that causes cells to make the chondroitinase enzyme and that can be switched on and off using a common antibiotic. A few weeks after the gene was switched on, the rats began to regain use of their front paws, with more skilled movements returning after about two months.
“The rats were able to accurately reach and grasp sugar pellets,” Dr Emily Burnside, a researcher from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at Kings College, told BBC News. “We also found a dramatic increase in activity in the spinal cord of the rats, suggesting that new connections had been made in the networks of nerve cells.”
Although the approach is not yet ready for trials in humans, researchers are hopeful that the technique could one day be used to help people with spinal cord injuries.
“We find this really exciting, recovery of this type of function, because for spinal injured patients their highest priority is to get their hand function back,” Professor Elizabeth Bradbury, also from IoPPN, told BBC News. “Being able to pick up a coffee cup, hold a toothbrush, these types of things will have a dramatic increase on their quality of life and their independence,” Bradbury explained.
In a press release, Bradbury said that the gene switch allows scientists to “precisely control how long the therapy is delivered. This means we can hone in on the optimal amount of time needed for recovery.”
The team encountered some difficulties with the immune system removing the gene switch and had to develop a way to effectively “hide” the switch.
Professor Joost Verhaagen, a scientist at the Netherlands Institute for Neuroscience who helped develop the stealth gene switch, said it “provides an important safeguard and is an encouraging step toward an effective gene therapy for spinal cord injury. This is the first time a gene therapy with a stealth on/off switch has been shown to work in animals.”
The researchers published their findings on Thursday in the journal Brain.