Gene therapy can bring dead bone back to life, researchers now say. The breakthrough could help thousands of individuals whose injuries or diseases necessitate bone transplants.
Doctors treat severe bone damage and cancer by replacing the affected bone with sections of bone from a cadaver. But this dead bone accumulates microfractures and breaks over time, requiring complicated reconstructive surgery or even amputation. That's because dead bone does not constantly repair itself like normal bone does. And unlike living bone, dead bone cannot help the body maintain proper calcium levels. It also forms scar tissue, cutting it off from the body's blood supply. Edward Schwarz, a molecular immunologist at the University of Rochester, New York, wondered if the key to converting dead bones into living ones was restoring this blood supply and calcium regulation.
To investigate, Schwarz and colleagues observed mice implanted with healthy and dead bone implants. They found two genes involved in blood vessel growth and calcium regulation that were turned on near the living bones but not near the dead ones. The team then incorporated these genes into a freeze-dried virus and painted it on dead bone before implanting it. The technique worked. The virus-coated bone tricked the body into infusing it with blood vessels and allowing it to regulate calcium release. This effectively turned the dead bone into living bone, says Schwarz. The team reported its results this week in Washington, D.C., at the annual meeting of the Orthopaedic Research Society and will publish its findings next month in Nature Medicine.
The work has important implications for certain types of cancer, says Arthur Gertzman, executive vice-president for research and development at the Musculoskeletal Transplant Foundation in Edison, New Jersey. "Schwarz's technique revitalizes the bone along its length and thickness" and will offer those with bone cancer an alternative to amputation, he says.