| Abstract |
Bone formation is subject in vivo to mechanical stimulation. Though many researches for bone cells of osteoblastic lineage sensing and responding to mechanical stimulation have been reported mainly in the biochemical field, the effects of mechanical stimulation are not so understood. In this study, in order to clarify the effects of mechanical vibration on osteoblast-like cells on the basis of the dynamic properties of the cells in the sense of vibration engineering, sinusoidal excitation was applied to the cells, and their cell proliferation and bone matrix generation were investigated as their frequency response. We developed an electromagnetic exciter of culture plates of the cells, which was designed with high stiffness to excite the whole area of the plates uniformly. We seeded MC3T3-E1, which is a mouse calvaria osteoblast-like cell line, and applied sinusoidal excitation for 24 hours a day for 28 days at the frequency of 12.5 or 100 Hz, setting the acceleration amplitude of 0.5 G to fix the inertia force to the cells. As the experimental results of counting the number of the cells using a hemocytometer, the cell density of all the vibrating groups was higher than that of the non-vibrating group after 14-day cultivation. In the most effective case of the frequency of 12.5 Hz and the cultured period of 25 days, the cell density of the vibrating group was higher than that of the non-vibrating group by about 26 %. That was also morphologically shown by the microscopic observation of the cells. By staining the cells with alizarin red S solution, the amount of the generated calcium salts as one of the bone matrices was measured. The amount of the calcium salts of the vibrating groups was higher than that of the non-vibrating group on 28-day cultivation. The number and the size of the nodules of the calcium salts were different depending on the excited frequency. These results of this study suggest that the mechanical vibration promotes the cell proliferation and the bone matrix generation, and that the effects of the mechanical vibration depend on the frequency.
|
