Using engineered skin and gingiva cells, researchers at the University of Michigan School of Dentistry say they have produced complete bones that have the same hard outer coating, spongy interior and marrow core as naturally produced bone.
Researchers used a developmental method to replace large areas of missing bone in living rats. They say this method could lead to less painful bone grafts in humans. Current bone grafting methods involve harvesting a patient’s bone marrow using a long needle or surgically removing a piece of bone, typically from the hip. The Michigan team’s research appeared in the May 20 issue of Human Gene Therapy.
In the developmental method, a tiny bit of skin or gingiva is removed, cut into even smaller pieces and placed in a culture dish. The cultured cells then are engineered to secrete BMP-7, a protein that induces bone formation. The cells are seeded onto collagen sponges that are placed in the area where bone repair is needed.
Researchers tested the method on rats that had large sections of bone missing from their skulls. New bone was produced from the rats’ own skin cells. The skulls were almost fully healed within four weeks, say researchers.
They say the new bone looks like naturally produced bone, and they are planning to conduct more experiments to find out whether it functions like natural bone.
They also are experimenting with using a hydrogel instead of collagen sponges. Hydrogel is a material that changes from liquid to gel under certain conditions. The particular hydrogel they use is like a "reverse Jell-O," which remains liquid when cool and firms up when warm, says study researcher Dr. R. Bruce Rutherford.
"Using a patient’s own cells from easily accessed tissues that heal quickly is a major step toward an alternative to conventional bone grafts," continued Dr. Rutherford. "If the implanted cells form bone directly, in addition to secreting BMP-7, these autografts would be useful in regenerating bone in many cases where few cells capable of forming new bone remain in the injured bone. Such lesions are difficult to treat by conventional treatment."
