Periosteal bone formation elicited by partially purified bone morphogenetic protein

A small amount of partially purified, water-soluble murine osteosarcoma-derived bone morphogenetic protein (BMP) was implanted into the dorsal muscles of mice in combination with calf skin gelatin or collagen as carriers. Changes in the ribs adjacent to the implants were then chronologically observed. On implantation of BMP with gelatin, the gelatin was rapidly absorbed and no ectopic bone formation was observed, but periosteal cellular proliferation with subsequent formation of periosteal cartilage and bone was seen in ribs adjacent to the implant. Implantation of the same amount of BMP fraction or gelatin alone as controls did not result in either any ectopic bone formation in situ or any periosteal bone formation in adjacent ribs. Implantation of BMP with collagen resulted consistently in both ectopic bone formation in situ and periosteal bone formation in adjacent ribs. These results suggest that BMP is diffusible in vivo and is capable of eliciting a response from periosteum to stimulate periosteal bone formation.