Gene therapy reduces neuropathic pain from spinal injuries

neuropathic pain
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A new Gene therapy investigation may offer hope for spinal cord injury patients who experience neuropathic pain, discovering that the treatment effectively reduces the debilitating symptom.

A University of California San Diego School of Medicine-led team of international researchers has identified a gene therapy that directly combats neuropathic pain. The novel treatment expertly targets nerve cell signalling and has demonstrated efficacy in mice with peripheral nerve or spinal cord injuries with no observable side effects.

Estimates suggest that there are between 249,000 and 363,000 people currently living with a spinal cord injury in the US alone, with the average age or the condition occurring being 43 years. Of these people, more than 50% suffer neuropathic pain, meaning this gene therapy breakthrough could enhance the lives of hundreds of thousands of people globally.

The results of the investigation are published in Molecular Therapy.

Impacts of neuropathic pain

Neuropathic pain is caused when nerves become damaged or stop functioning correctly, causing severe or debilitating numbness, muscle weakness, and pain. Currently, there are no wholly effective single treatments for the condition.

For example, pharmaceutical remedies usually consist of a complicated and consistent administering of drugs that often produce adverse side effects, including sedation and reduced motor function. Additionally, despite opioids being a practical solution, their use can also lead to increased tolerance, and there is a risk of the patient either misusing or abusing the drugs.

In patients with spinal cord injuries, physicians and researchers can accurately locate the exact origin of neuropathic pain. This has led to increased effort to design treatments that can selectively target impaired or damaged neurons in the affected spinal segments.

Pioneering gene therapy treatments

Gene therapy has arisen as an exciting avenue for alleviating neuropathic pain in recent years. For their study, the researchers injected a harmless adeno-associated virus that contained a pair of transgenes that encode for gamma-aminobutyric acid (GABA) into mice that had neuropathic pain caused by sciatic nerve injuries. GABA is a neurotransmitter that inhibits impulses between nerve cells and, in this case, pain signals.

The results showed that the gene therapy mitigated the expression of the GAD65 and VGAT transgenes, restricting them to the area of sciatic nerve damage in the mice. This resulted in no detectable side effects, such as motor weakness or loss of normal sensation. Furthermore, GABA production by the transgenes caused a measurable blocking of pain-signalling neurons that lasted for at least 2.5 months following the treatment.

Martin Marsala, MD, the senior author of the study and a professor in the Department of Anesthesiology at the UC San Diego School of Medicine, concluded: “One of the prerequisites of a clinically acceptable antinociceptive (pain-blocking) therapy is minimal or no side effects like muscle weakness, general sedation or development of tolerance for the treatment. A single treatment invention that provides a long-lasting therapeutic effect is also highly desirable. These findings suggest a path forward on both.”

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