NIST AIDS development of new bone graft materials. (News Briefs).

Scientists from NIST and research associates from the American Dental Association Health Foundation have demonstrated a new approach to bone regeneration. More than 100 000 bone grafts are performed each year in the United States, but the amount of available autologous bone is limited and available material is difficult to shape. Furthermore, the number of bone grafts will likely increase as the population ages. Thus, the development of a synthetic, moldable bone graft is the primary goal of tissue engineered products industry.

The new approach extends previous work by the American Dental Association Health Foundation at NIST on a self-setting calcium phosphate cement that can be sculpted to fit the contours of a wound. This cement was improved in recent work by making it macroporous and osteoinductive through inclusion of polymer microspheres and a bone growth factor, respectively. The polymer microspheres, called porogens are made of a biodegradable polymer that initially stabilizes the graft, but then can degrade gradually, leaving pores of the appropriate size for colonization by osteoblasts. The calcium phosphate cement matrix would slowly dissolve and be replaced by new bone. The NIST research has shown that in cell media the polymer-modified cement undergoes complete degradation of the porogens, leaving a porous structure. Osteoblast-like cells were shown to adhere, attain a normal morphology, proliferate and remain viable when cultured on the new composite graft. The calcium phosphate cement is further improved by providing controlled release of an osteoinductive protein that facilitates growth of new bone. Studies have shown that adjusting the amount of porogens could modulate the protein release kinetics.

The NIST work has attracted the interest of biotechnology companies that focus on the development of synthetic bone grafts.

CONTACT: Francis Wang, [phone]; francis. [e-mail].