Micro- and Nano-Scopic Biomechanics of Articular Cartilage Focusing Chondrocytes and Surrounding Tissue

随着老年人口的发展，特别是在日本，由于骨关节炎、类风湿性关节炎或自然滑膜关节损伤而导致行走能力残疾的老年人预计会增加。在天然滑膜关节中，关节软骨在承载机制和润滑机制中起着重要作用。骨关节炎的发生被认为是由于滑膜关节润滑能力不足和关节软骨承载能力丧失所致。关节软骨由细胞外基质（ECM）和软骨细胞组成。本研究旨在从宏观、微观和纳米三个角度阐明关节软骨（包括软骨细胞）的应力-应变行为和自然滑膜关节的适应性多模式润滑机制，以预防骨关节炎的进展和改善再生软骨的功能。 ...更多信息 LSM）通过观察染色软骨细胞的荧光图像来估计关节软骨在压缩下的局部应变。采用激光共聚焦扫描电镜研究了关节软骨的应变行为随时间和深度的变化。这些力学行为进行了评估，通过双相有限元法（FEM）。这些应力-应变行为对由软骨细胞控制的代谢具有影响，预期软骨细胞产生周围ECM，包括蛋白聚糖和胶原。采用弹性模量随深度变化的双相有限元方法，模拟了半圆柱形软骨试件随深度变化的剖面变形和随时间变化的应变行为。通过考虑弹性模量的一阶增长或在两相模型中引入胶原纤维等弹性元件，得到了高应变率下压缩后峰值压缩应力与随后的应力松弛的对应关系。此外，软骨细胞-琼脂糖构建体的弹性模量增加表明循环压缩刺激对培养的软骨细胞的影响。少

The increase of elder persons disabled with walking ability due to osteoarthritis, rheumatoid arthritis or damages of natural synovial joints is anticipated with progress of population of aged people particularly in Japan. In natural synovial joint, the articular cartilage plays important roles in load-carrying mechanism and lubrication mechanism. The initiation of osteoarthritis is considered to be brought about by the deficiency of lubricating ability in synovial joints and loss of load-carrying capacity of articular cartilage. The articular cartilage is composed of extracellular matrix (ECM) and chondrocyte. The object of this research is to elucidate the stress-strain behaviors of articular cartilage including chondrocytes and the adaptive multimode lubrication mechanism in natural synovial joints from the macro-, micro- and nanoscopic viewpoints, to prevent the progress of osteoarthritis and to improve the function in regenerated cartilage.The confocal laser scanning microscopy (C … More LSM) was used to estimate the local strain of articular cartilage under compression by observing the fluorescent images of stained chondrocytes. The time-dependent and depth-dependent strain behaviors of articular cartilage were investigated by CLSM. These mechanical behaviors were evaluated by the biphasic finite element method (FEM). These stress-strain behaviors have an influence on metabolism controlled by chondrocytes which is expected to produce surrounding ECM including proteoglycan and collagen. The depth-dependent profile deformation and time-dependent strain behavior of semi-cylindrical cartilage specimen was simulated by biphasic finite element analyses considering depth-depending elastic modulus. The correspondence to the peak compressive stress and following stress relaxation immediately after compression at high strain rate was attained by consideration of one order raising of elastic modulus or by introducing of spring element like collagen fiber to biphasic model. Furthermore, the effect of cyclic compressive stimulation on cultured chondrocytes was indicated by an increase in elastic modulus of chondrocyte-agarose construct. Less