Blocking the Burn of Neuropathy

Constant burning pain in the hands and feet is a common complication of many diseases, especially diabetes. Drugs have little effect on this type of neuropathic pain, which is caused by damage to sensory neurons that transmit pain, temperature and touch signals to and from the brain.

David Fink, with study collaborators Marina Mata, M.D. (Residency 1981), and Shuanglin Hao, M.D., Ph.D. Photo: Martin Vloet

Now, scientists at the VA Ann Arbor Healthcare System and the University of Michigan Medical School have found a way to block the signals responsible for neuropathic pain. They use a genetically altered, non-infectious form of herpes simplex virus to deliver genes to the nucleus of neural cells near the spine.

“Patients with neuropathic pain suffer tremendously and the treatments available to us have limited effectiveness,” says David J. Fink, M.D., the Robert W. Brear Professor of Neurology in the U-M Medical School. “Using the herpes vector to provide targeted gene delivery to the nervous system is a novel approach that shows tremendous promise for the treatment of neuropathic pain.”

The herpes simplex virus has a natural ability to travel long distances along nerve fibers from the skin to the neural cell’s nucleus next to the spinal cord. This makes it the perfect gene delivery vehicle for use in the nervous system.

In a study published in the June 2005 issue of the Annals of Neurology, Fink and his research colleagues described how laboratory rats with nerve damage showed much less pain-related behavior after receiving injections of the herpes simplex virus-based vector containing a gene that triggers production of an inhibitory neurotransmitter, which blocks the transmission of pain signals. The treatment’s pain-killing effect lasted up to six weeks, and even longer in rats that received additional injections.

In future research, the scientists plan to conduct the first phase I safety trial of a related vector in patients with pain caused by terminal metastatic cancer.

—SFP

For an expanded version of the story:
www.med.umich.edu/opm/newspage/2005/neuropathicpain.htm

For patient information on neuropathy:
www.med.umich.edu/1libr/aha/aha_perineur_crs.htm