Study on the Dynamic Properties of Living-Cells from the viewpoint of Intelligent Vibration-Reducible Structure

生物基本上是由细胞组成的，细胞可以适应环境；他们聚在一起寻找相同类型的细胞，排除对它们不利的刺激，并保持最佳状态以保存生命。虽然这些细胞已经在生物学、医学、生物化学等领域得到了广泛的研究，但当它们被视为微型机器的雏形时，可能会引起机械工程师的注意。但是，几乎没有人研究过细胞的力学特性。这个项目集中于揭示活细胞的力学特性，并将其应用于建造更智能的结构。作为活细胞，骨相关细胞被用于本研究。骨细胞对周围的力学条件具有适应性。据报道，负责骨形成的成骨细胞对机械振动有反应，并改变细胞增殖和骨量的产生。为了更好地研究成骨，有必要从机械工程的角度了解细胞的弹性或黏性等力学特性。就骨细胞而言，由于它们附着在骨基质表面，因此了解其在粘附条件下的力学性能是很重要的。在本研究中，我采用正弦变形法测量了培养成骨细胞MC3T3-E1在粘附条件下的动态粘弹性。利用这些实验结果，我们推导了粘弹性的Voigt模型，并确定了各个参数的值。其次，评估机械刺激的效果。对骨骼的机械刺激影响成骨，如宇航员在零重力下骨量的减少和用超声设备修复骨折。骨细胞在形态学和代谢水平上感知和响应机械刺激。从机械振动的角度来看，骨细胞根据机械刺激及其力学特性发生变形。据报道，使用拉伸和蠕变试验测量了细胞的粘弹性，并且在结构动力学意义上可能存在细胞的固有频率和非线性。提示骨细胞对成骨的机械刺激存在有效的频率和幅度。本研究通过对培养成骨细胞MC3T3-E1施加正弦惯性力，研究机械振动频率和加速度幅值对细胞增殖、骨基质生成和碱性磷酸酶（ALP）基因表达的影响。少

Living creatures are fundamentally composed of cells, which may adapt to their environment; they get together finding the same kind of cells, exclude inconvenient stimulus to them, and keep the best condition for life conservation. Though the cells have been treated in biology, medical science, or bio-chemistry, they may be paid attention by mechanical engineers when they are regarded as a prototype of micro-machine. But, almost nothing has been studied as for the mechanical properties of cells. This project is concentrated to reveal mechanical properties of living cells and they are applied to construct more intelligent structures. As living cells, a bone related cell are used in this study.Bone cells have adaptability to the surrounding mechanical condition. Osteoblasts, which are responsible for bone formation, were reported that they responded to mechanical vibration and changed the cell proliferation and the amount of generated bone mass. In order to find the effective stimulation … More on osteogenesis, it is necessary to understand the mechanical properties such as elasticity or viscosity of the cells in the view of mechanical engineering. In the case of bone cells, it is important to understand the mechanical properties under adhesive condition because they attach on surfaces of bone matrices. In this study, I measured dynamic viscoelasticity of a cultured osteoblast, MC3T3-E1, under adhesive condition by applying sinusoidal deformation. Using these experimental results, we derived Voigt model for viscoelasticity and identified the value of each parameter.Next, the effect of mechanical stimulation was evaluated. Mechanical stimulation to bones affects osteogenesis such as decrease of bone mass of astronauts under zero gravity and fracture repair with ultrasound devices. Bone cells have been reported to sense and response to mechanical stimulation at cellular level morphologically and metabolically. In the view of mechanical vibrations, bone cells are deformed according to mechanical stimulation and their mechanical characteristics. It was reported that viscoelasticity of cells was measured using tensile and creep tests and that there was likely natural frequency and nonlinearity of cells in the sense of structural dynamics. It suggests that there is effective frequency and amplitude of mechanical stimulation on osteogenesis by bone cells. In this study, sinusoidal inertia force was applied to cultured osteoblasts, MC3T3-E1, and effects of frequency and acceleration amplitude of mechanical vibration on the cells were investigated in respect of the cell proliferation, bone matrix generation and alkaline phosphatase (ALP) gene expression. Less