Fig. 3.

In vivo effect of BMP2 and -7 on bone, periosteum and muscle compartment. (a) At the endosteal surface BMP2 affects both osteoclasts and osteoblasts with a net outcome of downregulation of Runx2, collagen I and Wnt signaling [75]; at the periosteum BMPs stimulate differentiation of precursor cells (green) into osteoblasts (orange); and in surrounding muscle cells (myoblasts, pericytes and vascular satellite cells) BMPs upregulate Id genes and form new osteoblasts and prechondrocytes to form cartilage and new bone around the cortical layer from which the new bone spreads into the medullar cavity. (b) As shown in patients with high tibial osteotomy and a fibular defect, BMP7 (Osigraft) stimulates bone formation from periosteum (P) and surrounding muscles (M) spreading endostealy at six and ten weeks to rebuild the cortical bone (CB) at one year following implantation (modified from [109])