Pictured here are active neural connections in a rat spinal cord. (Photo courtesy of King’s College London.)

Pictured here are active neural connections in a rat spinal cord. (Photo courtesy of King’s College London.)

Spinal cord-injured rats treated with gene therapy can relearn skilled hand movements, suggest researchers from King’s College London in a study published recently in Brain.

In the study, researchers tested a new gene therapy for regenerating damaged tissue in the spinal cord that could be switched on and off using a common antibiotic.

“What is exciting about our approach is that we can precisely control how long the therapy is delivered by using a gene ‘switch’, says Professor Elizabeth Bradbury from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN), in a media release.

“This means we can hone in on the optimal amount of time needed for recovery. Gene therapy provides a way of treating large areas of the spinal cord with only one injection, and with the switch we can now turn the gene off when it is no longer needed.”

After a traumatic spinal injury, dense scar tissue forms that prevents new connections being made between nerve cells. The gene therapy causes cells to produce an enzyme called chondroitinase, which can break down the scar tissue and allow networks of nerve cells to regenerate.

Most human spinal cord injuries occur at the neck level and affect all four limbs. The researchers gave the gene therapy to rats with spinal injuries that closely mimicked the kind of human spinal injuries that occur after traumatic impacts such as car crashes or falls, explains the release, from King’s College London.

“Rats and humans use a similar sequence of coordinated movements when reaching and grasping for objects. We found that when the gene therapy was switched on for 2 months the rats were able to accurately reach and grasp sugar pellets. 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,” states Dr Emily Burnside from the IoPPN, per the release.

The researchers had to overcome a problem with the immune system recognizing and removing the gene switch mechanism. To get around this, the researchers worked with colleagues in the Netherlands to add a “stealth gene,” which hides the gene switch from the immune system.

“The use of a stealth gene switch provides an important safeguard and is an encouraging step toward an effective gene therapy for spinal cord injury,” shares Professor Joost Verhaagen at the Netherlands Institute for Neuroscience.

The gene therapy is not yet ready for human trials. While the ability to switch a therapeutic gene off provides a safeguard, the researchers found a small amount of the gene remained active even when switched off. They are now working on shutting the gene down completely and moving towards trials in larger species, the release concludes.

[Source(s): King’s College London, Science Daily]