Spinal cord injuries often mean the loss of ability to perform everyday actions that require coordinated hand movements. Regaining hand function is top priority for patients as it would improve quality of life and independence. Currently there are no regenerative treatments available. A new gene therapy is being tested for regenerating damaged tissue in the spinal cord that can be switched on or off using antibiotics, making it possible to treat large areas with one injection and switch the gene off when no longer needed, optimizing recovery time.
Dense scar tissue forms after traumatic spinal injury that prevents new connections from being made between nerve cells. Gene therapy causes cells to produce chondroitinase enzymes that can break down scar tissue allowing networks of nerve cells to regenerate. Most spinal cord injuries occur at neck level affecting all four limbs. Gene therapy was given to model rats of human spinal injury, as rats and humans use similar sequences of movements to reach and grasp objects.
After overcoming the problem of immune system removing the gene by developing a stealth gene to add to the switch gene to hide it from the immune system, is was administered to the model animals. When given gene therapy for two months with the gene turned on the animals were able to reach and grasp sugar pellets. Dramatic increase of activity was observed in their spinal cords, suggesting new connections had been made with networks of nerve cells. The stealth gene provides an important safeguard which effectively aids gene therapy, this was the first time of such a gene therapy with stealth on/off switch to be shown to work effectively in animals, according to the researchers.
Although not yet ready for human trials, the ability to switch a therapeutic gene off is an important additional safeguard and encouraging development in spinal cord gene therapy. A small amount of the gene was found to remain active after being turned off, researchers are now working to shut the gene down completely and moving on to trial with larger models.
