Figure 3: Adaptive osteoblastic differentiation to compressive stress.
From: Magnitude-dependent response of osteoblasts regulated by compressive stress
In MC3T3-E1 cells, Runx2, and Ocn mRNA increased significantly only when the compressive stress of 2 g/cm2 was applied (a,c). Alp mRNA increased significantly in all stress-loaded groups and the cells exposed to 2 g/cm2 and showed the highest average value (b). In POBs, Runx2, and Ocn mRNA expression also increased significantly in the group exposed to 2 g/cm2 (d,f). Alp mRNA expression increased significantly in all stress-loaded groups except 5 g/cm2, as well as showed the highest average value in the group exposed to 2 g/cm2, similar to MC3T3-E1 cells (e). The protein expression levels of RUNX2, ALP, and OCN in MC3T3-E1 cells were examined by Western blot. RUNX2, ALP, and OCN all increased significantly when a compressive stress of 2 g/cm2 was applied (g–i). Representative immunoblotting images are shown (j). With 14 days of continuous osteogenic induction, ALP activity increased significantly in MC3T3-E1 cells (k) and POBs (l) exposed to stress of any magnitude. The cells under compressive stress of 2 g/cm2 exhibited peak average values. Data are displayed as the mean ± SD from one representative of two (for Western blot) or three (for PCR and ALP activity) independent experiments (n = 5 per group). “p” denotes the significance level compared with the group exposed to 0 g/cm2 (control). *p < 0.05.
