Synergistic effects of fibroblast growth factor-2 and bone morphogenetic protein-2 on bone induction

The present study investigated the synergistic effect of co-administering fibroblast growth factor-2 (FGF-2) and bone morphogenetic protein-2 (BMP-2) on osteoblastic differentiation in C2C12 cells and in rats. C2C12 murine myoblast cells represent a well-accepted in vitro model system to study the ability of BMP-2 to alter cell lineage from the myogenic to the osteogenic phenotype. The osteoblastic differentiation potency was determined by alkaline phosphatase (ALP) and Alizarin red S staining. ALP activity and calcium concentrations were colorimetrically measured. Simultaneous administration of 4 mu g/ml recombinant human BMP-2 with 2 ng/ml FGF-2 markedly enhanced ALP activity (an early marker of osteogenesis) of C2C12 cells. This combination also increased extracellular signal-regulated kinase1/2 mitogen activated protein kinase signaling that is involved in the promoting effect of FGF-2 on BMP-2-induced osteoblastic differentiation in C2C12 cells. Calcium deposition (a late marker of osteogenesis) and the expression of CD34 (a marker of new vessels) were promoted optimally by simultaneous local sustained administration of FGF-2 and BMP-2 using collagen and chitosan-coated antigen-extracted porcine cancellous implants in a rat ectopic implantation model. The synergistic effects of a combination of BMP-2 and FGF-2 may have potential for bone regenerative therapeutics.