Use of an osteoinductive biomaterial as a bone morphogenetic protein carrier

A porous calcium phosphate ceramic, which induced bone formation in soft tissues of dogs, was termed as osteoinductive biomaterial and studied as a carrier of bone morphogenetic protein (rhBMP-2). Cylinder implants (empty set 4x5 mm) impregnated with 0, 1, 10 and 40 mug rhBMP-2 were implanted in dorsal muscles of rabbits for five weeks. Histological observation and histomorphometric analysis were performed on thin un-decalcified sections. No bone formation was detected in the implants without rhBMP-2, while mature lamellar bone was found inside the implants with 1 mug rhBMP-2, both on the outer surface and inside the implants with 10 mug and 40 mug rhBMP-2. Little difference in formed bone was found between 1 mug and 10 mug rhBMP-2, but no difference was found between 10 mug and 40 mug rhBMP-2. A significant difference in bone marrow formation was found among 1, 10 and 40 mug rhBMP-2. The more rhBMP-2, the more bone marrow formed. The present results indicate that osteoinductive biomaterial is a good carrier of BMP and high dose of BMP is not necessary for bone formation in clinic. (C) 2001 Kluwer Academic Publishers.