A Study of a Cell Mechanosensing System Under Mechanical Vibration Considering its Modes of Vibration and Calcium Ion Response

Abstract

It was reported that osteoblastic cells respond to mechanical vibration and generate the bone mass with a peak at a specific frequency like a resonance curve [1]. There seems to be an analogy between its cell response and the resonance of a cell as a mechanical system. This paper describes a novel method to measure the cellular modes of vibration of a cell and its calcium ion response under mechanical vibration, and the evaluation of the obtained results to clarify the mechanism of the cell mechanosensing. Nuclei and calcium ion in osteoblastic cells were visualized with fluorescent labelling. Mechanical vibration was applied to cells in a dish in the horizontal direction under a confocal laser scanning microscope by an exciter. Since the fluorescent intensity was very weak due to high frame rate to capture moving cells under Mechanical vibration, we used a high-speed and high-sensitive camera adjusting various conditions such as exposure time. We realized the spatial resolution of approximately 2 μm in the captured micrographs even under mechanical vibration using the experimental setup. As a result, the modes of vibration of nuclei was not obtained in this resolution. We found that the intracellular calcium ion concentration began to increase in a few seconds after mechanical vibration was applied. This experimental result indicates that applying mechanical vibration to cells can produce calcium signals as a second messenger by causing the entry of the ion.