Serial administration of rhBMP‐2 and alendronate enhances the differentiation of osteoblasts

The incorporation of growth factors is an effective strategy to accelerate bone induction. Bone morphogenetic protein-2 (BMP-2) promotes osteoblast differentiation and induces bone formation. Alendronate (ALN) is an osteoclast deactivation drug. We investigated the effect of serial administration of recombinant human BMP-2 (rhBMP-2) and ALN on osteoblast differentiation.The effect of serial administration of rhBMP-2 (0-150 ng/mL) and ALN (0-15 µmol/L) on the viability and differentiation of a clonal murine calvarial cell line, MC3T3-E1, was evaluated at various concentrations and for different periods. The Cell Counting Kit-8 assay was used to assess cell viability. The alkaline phosphatase activity was evaluated as an indicator of osteogenic differentiation. The expression levels of runt domain-containing transcription factor 2 (Runx2) and osteopontin (OPN) were analyzed by real-time polymerase chain reaction and western blotting. Statistical analyses were performed using Student's t test.The serial treatment with rhBMP-2 and ALN increased the expression of the differentiation-related factors Runx2 and OPN, as well as the differentiation ability of osteoblasts compared with individual or simultaneous treatment. The osteoblasts treated with rhBMP-2 followed by ALN showed the highest differentiation. The degree of differentiation in the group treated with rhBMP-2 for 7 days followed by ALN for 3 days was increased by 1.5 times compared with that of the group treated with rhBMP-2 alone (P < .01).These findings indicate that the serial administration of rhBMP-2 and ALN may exert osteogenic effects on osteoblastic cells via the upregulation of Runx2 and OPN.