In vitro osteogenic response of rat bone marrow cells to bFGF and BMP-2 treatments.

Basic fibroblast growth factor (bFGF) and bone morphogenetic protein-2 (BMP-2) are actively pursued for stimulation of bone formation. To assess their promise for systemic therapy of osteoporosis, we ascertained the effects of bFGF and BMP-2 on bone marrow cells in vitro. Bone marrow cells were obtained from young (8 weeks) and adult (32 weeks) rats by femoral aspiration and were exposed to osteogenic medium (ie, basal medium with 10 mM beta-glycerolphosphate and 100 nM dexamethasone) containing the growth factors. The cell viability in osteogenic medium was reduced after 3 weeks but not if the concentration of beta-glycerolphosphate/dexamethasone was reduced to 3 mM/30 nM. Unlike BMP-2, bFGF at 2-50 ng/mL was capable of enhancing long-term cell viability. Continuous treatment of bone marrow cells for 3 weeks resulted in dose-dependent stimulation of mineralization by BMP-2, but not by bFGF, whose activity was optimal at 2-10 ng/mL. To explore the effect of short-term exposure, bone marrow cells were treated with growth factors for 1 week and subsequent mineralization was investigated. BMP-2 exposure increased the extent of mineralization, but bFGF was not effective after the short exposure. We concluded bFGF was more potent (ie, required lower concentration) for stimulating osteogenic parameters, but BMP-2 effects were lasting on the bone marrow cells.