Development of vibration mechanical stimuli loading device for live cell fluorescence microscopy

Bone metabolism is regulated by mechanical stimuli such as gravity and exercise. If bone formation can be promoted by artificial mechanical stimulation, the quality of life of the aging society can be improved, such as by reducing the progression of osteoporosis and preventing patients from being bedridden. Micro-vibration stimulation with frequencies of 15 Hz to 90 Hz and acceleration amplitudes of 0.1 g to 0.3 g is effectively promotes bone formation in animal models. However, the mechanism of how these weak vibrations are sensed by bone cells and are used to regulate bone metabolism is unknown. In this study, we developed a device to apply micro-vibration stimuli to osteoblasts cultured on a glass bottom dish and observed the cell response to the stimuli using a confocal laser scanning fluorescence microscope. The device performance was confirmed using driving tests, and the calcium signaling response of osteoblasts to micro-vibration stimuli was observed in real time and in situ. The calcium signaling response characteristics of the cells differed when the cells were subjected to 45 Hz and 90 Hz micro-vibration stimuli, even under a constant acceleration amplitude of 0.2 g