Several growth factors speed the healing of muscle injuries in animal models, according to a report at this year's Orthopaedic Research Society meeting in Anaheim, Calif., by a research team from the University of Pittsburgh's Musculoskeletal Research Center and the Growth and Development Laboratory at Children's Hospital of Pittsburgh. This work paves the way for these compounds to be used one day in people with similar injuries, according to investigators there.
"Specific growth factors we used not only improved muscle regeneration; they quickened healing. These results open new horizons for the treatment of all types of muscle injuries," noted Johnny Huard, Ph.D., principal investigator on the study, assistant professor of orthopaedic surgery and of molecular genetics and biochemistry at the University of Pittsburgh and director of the Growth and Development Laboratory.
Muscle healing after an injury often is slow and incomplete because dense scar tissue forms at the site of an injury. "By injecting growth factors into a patient's muscle right after it suffers an injury, we might be able to stimulate the growth of functional muscle fibers, rather than see scar tissue develop. In this way, patients could expect to regain more muscle use than if they were simply treated with immobilization, rest or range of motion exercises," added Dr. Huard.
Many people suffer costly and disabling muscle injuries. For athletes, muscle injuries may end their careers because they cannot compete the same as before injury.
In their experiments, the investigators created an injury in both gastrocnemius (calf) muscles of 42 mice. The mice were then divided into three sets of 14 apiece. Each set received a different growth factor, either insulin growth factor type (IGF-1), basic fibroblast growth factor (b-FGF) or nerve growth factor (NGF). One gastrocnemius muscle in each mouse served as a control, receiving an injection of fluid alone.
After one month, the researchers tested the function of the muscles and looked at their composition. Injured muscles that had received IGF-1 or b-FGF were stronger than the control muscles. These muscles also had advanced muscle regeneration throughout the injured area, as well as reduced scar tissue when compared with control muscles. NGF produced no significant benefit.