Chondroosteogenetic response to crude bone matrix proteins bound to hydroxyapatite.

For the development of a new implantable biomaterial that possesses osteogenetic ability, bone matrix morphogenetic proteins were bound to hydroxyapatite (BMP-HAP). A crude protein extract including the bone morphogenetic protein (BMP) fraction was precipitated in the pores of hydroxyapatite (HAP) inside of a dialysis sac. In tissue culture, BMP-HAP or HAP was used as substratum for rat mesenchymal muscle cell explants. The BMP-HAP and HAP controls were also implanted in the muscle pouches of mice. New cartilage and/or new bone formation was observed on the exterior surface of BMP-HAP but not of HAP controls. Implantation of this HAP into bone marrow cavities of rabbit femoral and tibial condyle produced new bone formation. The deposits extended further inside BMP-HAP than HAP pores. The pore diameters of 90-200 microns produced earlier ingrowth than into larger pore sizes. BMP-HAP should be tested for clinical application as osteogenetic biomaterial for augmentation of bone regeneration.