Page 97 - Physico-Chemical Niche Conditions for Bone Cells

oscillating between 0 and 212 Pa at each pulse, which was similar to the average fluid pressure on the cell at all time-points measured (Fig. 2H).
The distribution of fluid shear stress over the pre-osteoblast was non-uniform (Fig. 2I). The average fluid shear stress over time reached the highest value (1.17 Pa) at 0.25 sec and every sec thereafter, while the lowest average fluid shear stress magnitude (0 Pa) was observed at 0.75 sec and every sec thereafter (Fig. 2J). The average fluid shear stress on the cell was oscillating between 0 and 1.17 Pa at each pulse (Fig. 2J). The fluid shear stress on the apex of the cell was oscillating between 0 and 0.79 Pa at each pulse (Fig. 2K). The magnitude of the average fluid shear stress on the cell was ~1.5-fold higher than the magnitude of fluid shear stress on the apex of the cell all time points measured. These results show that the fluid velocity, and fluid shear stress magnitude varied at different regions of the pre-osteoblast over time as a result of PFF, while fluid pressure magnitude was constant at different regions of the pre-osteoblast and changed over time as a result of PFF.
Initial down-stream impact of PFF (minutes)
NO production
The absolute amount of NO production by MC3T3-E1 pre-osteoblasts in response to PFF was significantly increased after 60 min (5.3-fold), but not after 10 min (6.0-fold) and 30 min (4.0- fold; Fig. 3A). Two-way ANOVA revealed a significant interaction effect between the different post-incubation times (0, 1, 3, and 6 h; p=0.0014).
Cell F-actin fluorescence
MC3T3-E1 pre-osteoblasts without and with PFF were spread well on glass slides. The morphology of the cells, without and with PFF, was oval-shaped to more polygonal-shaped (Fig. 3B, D). F-actin fluorescence (green, static control) intensity was 88.14±46.22 arbitrary units (a.u.; mean±SD; Fig. 3C). PFF-stimulated F-actin fluorescence intensity was 105.16±34.21 a.u. (mean±SD; Fig. 3E).
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