Gene therapy helps arthritis pain, damage in mice

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - A gene therapy treatment that helped make cells more sensitive to the body's own painkillers not only helped ease arthritis pain in mice but also reduced other symptoms, researchers said on Friday.

The researchers are now trying to get permission to try the treatment in people.

"This therapy can simply be injected anywhere in an injured joint, and the treatment will find the nerve endings," said Dr. Stephanos Kyrkanides of the University of Rochester Medical Center in New York, who led the study.

The researchers used a well-tested method of gene therapy, employing a virus called an adeno-associated virus to carry a new gene into the body. In this case, the new gene was one called the human mu-opioid receptor -- a kind of molecular doorway that the body's natural painkillers use to get into cells.

The more of them a cell has, the more sensitive it is to these painkilling chemicals.

The Kyrkanides team had mice genetically engineered to develop osteoarthritis in the same way that people do. They injected their gene-engineered virus into various joints.

"That strategy not only significantly reduced the pain behavior in the mice with arthritis, but it also helped to minimize the arthritis pathology itself," Kyrkanides said.

This suggests that the pain receptors play a role not only in the pain but also in the joint damage caused by arthritis, he said.