[Feasibility of quantified fluid shear stress loading on osteoblasts through rocking system]

To study the biomechanical behaviors of the cells, reliable fluid shear stress loading system is needed. Compared to the traditional parallel plate flow chamber (PPFC) system, a rocking system presented by Zhou offers some advantages such as easier operation, lower cost and higher quantity of pocessing. But the feasibility of it has not been practically studied. To investigate the feasibility whether the rocking system can be used to apply quantified fluid shear stress loading, primary osteoblasts of mouse were loaded with fluid shear stress based on rocking system and traditional PPFC system, respectively. Another group of cells was unloaded as control. The cytoskeleton was observed with laser scanning confocal microscope (LSM) and average fluorescence of F-actin was recorded. Cell cycle was also measured by flow cytometry and percentage of S-phase cells was recorded. The result showed that average fluorescence of F-actin was enhanced after rocking system loading (46.8 +/- 4.5) compared to the control (20.4 +/- 1 8) and the percentage of S-phase cells was increased (10.6 +/- 1.04) after rocking system loading as well (which was 4.1 +/- 0.54 in control group). Furthermore, the fluid shear stress generated by rocking system could induce more significant biological effects compared to PPFC system. This study demonstrated that fluid shear stress generated by rocking system could induce biological effects of osteoblasts, and it could simulate the micro environment of cells in vioe better than PPFC. Rocking system is a convenient and feasible method for fluid shear stress loading.