It's called neuropathic pain, and it's a common complication of many diseases and medical conditions, especially diabetes. Drugs have little effect on this type of pain, which is caused by damage to sensory neurons that transmit pain, temperature and touch signals to and from the brain.
Now, scientists at the VA Ann Arbor Healthcare System and the University of Michigan Medical School have developed a way to block the signals responsible for neuropathic pain. The secret to their success is based on a virus called herpes simplex or HSV ?the same virus that causes cold sores and genital herpes. The scientists use a disabled form of the virus, called a vector, to deliver genes to the nucleus of neural cells.
A study published today in the June, 2005 of the Annals of Neurology describes how laboratory rats with nerve damage showed much less pain-related behavior after receiving injections of the HSV-based vector, which contained a gene called GAD, or glutamic acid decarboxylase. The treatment's pain-killing effect lasted up to six weeks, and even longer in rats that received additional injections.
The study is the first to demonstrate the successful use of gene transfer technology, using a herpes viral vector, to treat peripheral neuropathic pain in animals. Based on their success in related studies with research animals, the scientists hope to conduct the first clinical study in human patients soon.
"We use the vector to provide targeted gene delivery to the nervous system," says David J. Fink, M.D., the Robert W. Brear Professor of Neurology in the U-M Medical School and staff neurologist at the VA Ann Arbor Healthcare System, who co-directed the research study. "In this case, we're not trying to correct a genetic defec
Source:University of Michigan Health Systems