Cells of ROS 17/2.8, a typical osteoblastic cell line, were cultured with or without continuous compressive force (0.5–2.0 g/cm2). Expression of mRNA encoding the osteogenesis-related transcription factors Runx2, Osterix, Msx2, Dlx5 and AJ18 was measured using real-time polymerase chain reaction. Protein expression of these transcription factors was determined by Western blotting.
A compressive force of 1.0 g/cm2 significantly increased mRNA and protein expression of Runx2, Osterix, Msx2 and Dlx5, which are critical for osteoblast differentiation. In contrast, mRNA and protein expression of AJ18, which downregulates osteoblast differentiation, were decreased with 1.0 g/cm2 of compressive force.
A compressive force of 1.0 g/cm2, which was considered optimal for bone formation under the present experimental conditions, stimulates osteoblastic differentiation via the modulation of osteogenesis-related transcription factors.