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Neuroscience research

Designer genes target serious diseases

 

No pain, big gain

Every semester, Sarah Sweitzer tries to bring in at least one person who suffers with chronic neuropathic pain to speak to her medical students. Some can't work anymore, and most get no relief from traditional drug therapies. "They come to class and tell the students, ‘Doctors think I'm a drug addict,'" Sweitzer said. "They can't get any break from the pain."

Seventy-five million Americans suffer from chronic pain (lasting at least three to six months), expending billions on medications that often don't work, can become addictive, or have unpleasant side effects.

Neuropathic pain has many causes -- spinal cord injury, amputations, tumors pressing against nerves, and the aftermath of shingles (herpes zoster) infections, to name a few.

"With our system, you can turn on the body's own pain-reducing chemicals, so you would need fewer prescription drugs -- maybe none at all -- for pain control."

Sweitzer is using an altered form of the herpes simplex virus, which normally causes cold sores, to target neuropathic pain. The herpes virus naturally infects and resides in peripheral neurons that signal pain, and Sweitzer's customized virus does something more: it carries a genetic signal that activates the body's natural opioid-producing system.

"With our system, you can turn on the body's own pain-reducing chemicals, so you would need fewer prescription drugs -- maybe none at all -- for pain control," Sweitzer said. "If you think of pain as a loss of balance between excitatory pain causing activity and inhibitory pain suppressing activity, we're using these viruses to both decrease excitatory pain activity and increase pain suppressing activity."

A research group in Michigan is using similar strategies to address pain issues with terminally ill cancer patients. If that work shows results, it could open the door for more gene-therapy clinical trials for chronic pain sufferers using the unique viruses made at the School of Medicine.

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