by Kimberly French, USTA Web Newsroom Senior Correspondent

Williamsport, PA — As long as horses populate the earth, they will combat osteoarthritis. Veterinary science has made significant progress in treating the disease but cannot eradicate or prevent it. This could change with the arrival of gene therapy treatments such as IRAP.

IRAP (interleukin-1 receptor antagonist protein) is the best known of a relatively recent group of anti-arthritis gene therapy treatments. It is a naturally occurring cytokine, or messenger protein, that accelerates tissue destruction by beginning the inflammation process.

If a joint becomes damaged, a messenger protein alerts the body to respond. Its reaction is inflammation which causes pain, synovitis, (inflammation of the fluid joint) and cartilage damage. If an antagonistic protein intercepts the messenger protein, the affected area does not produce pain.

IRAP therapy is a gene sequence that recreates a horse’s natural antagonistic protein. This protein is transformed into a harmless virus and injected into the affected equine joints. The virus takes over the joint’s cells and uses the horse’s own body to produce more IRAP.

Dr. David Frisbee, D.V.M., Ph.D., is an associate professor of clinical sciences at Colorado State University and a leading researcher on this form of treatment. In his report to the Symposium on Gene Therapy in 2000, Frisbee found IRAP to be highly successful.

“Following a single injection of adenoviral vector (the virus containing IRAP), we demonstrated a decrease in lameness, synovitis and osteoarthritis,” Dr. Frisbee said.

An equine IRAP therapy patient would have 50 to 60 milliliters of blood drawn from the jugular vein through an Orthokine syringe. This specially constructed instrument contains glass beads that stimulate the white blood cells to produce IRAP. The incubation process takes place in the syringe over 24 hours.

The amount and duration of treatment varies. The amount of IRAP used depends on the size of the joint. The typical amount injected is from two to four milliliters up to six to eight milliliters. In most cases, two to three treatments are given eight to 14 days apart.

At this time, IRAP has no known side effects except those common to all joint injections — the risks of infection and the development of scar tissue from the needle entering the joint. However, it does have several advantages; it doesn’t have a negative effect on cartilage, it’s beneficial in high motion joints and since no drugs are involved, it’s highly applicable when drug tests are performed.

IRAP represents the latest innovation in the treatment and prevention of joint disease but relies on an ancient process that may be essential to its success — allowing the body to heal itself.