A bone regeneration study: transforming growth factor-beta 1 and its delivery

Critical-sized defects (CSDs) were prepared in 60 rabbit skulls, divided evenly among five treatments and two time periods. The treatments consisted of rabbit demineralized bone matrix (DBM) and four different doses of transforming growth factor-beta 1 (TGF-beta 1) (0, 0.4, 4, and 40 micrograms) delivered in 3% carboxymethyl cellulose and Gelfilm. Quantitative assessments of bone formation in the CSDs were accomplished with computerized radiomorphometry and histomorphometry. Results indicated that rabbit DBM and 40 micrograms TGF-beta 1 promoted more new bone formation at 4 weeks than the other treatments. By 8 weeks, bone formation in the CSDs was equivalent for all but the 0-microgram dose of TGF-beta 1. The results from the study suggest a single therapeutic dose of TGF-beta 1 delivered in an appropriate carrier to a critical-sized intraosseous wound should promote bone formation.