Effects of tribological stimulation on chondrocyte metabolism and development of functional cartilage tissue structure for joint lubrication

关节软骨是一种独特而有趣的软组织，它覆盖着腹股沟关节的关节表面，在实现关节平稳运动中起着重要的“承重”作用。然而，调控软骨表面复杂摩擦学功能建立过程的详细机制尚不清楚，本研究的目的是通过软骨细胞对关节运动过程中所经历的机械负荷的代谢反应，来研究关节润滑的功能性软骨组织结构的发展过程。众所周知，嵌入软骨组织中的软骨细胞可以感知施加在组织上的机械应力和应变。软骨细胞随后通过机械转导途径调节自己的新陈代谢，并维持软骨组织的功能结构。在本研究中，我们开发了一种滚动-滑动摩擦加载机，该加载机采用…更多的h可以在实验上再现摩擦学刺激，如压缩应变、剪切应变和流体剪切，这些刺激是关节连接过程中摩擦力施加在软骨表面的。将加载机安装在CO2培养箱中，在琼脂糖凝胶中对三维培养的软骨细胞施加摩擦学刺激，检测摩擦学刺激对软骨细胞生物合成细胞外基质和组织结构发育的影响。然后，用PYREX玻璃辊对试件表面进行纯滑动，持续2小时，每天2次，连续5天。结果表明，纯滑动能增加糖胺多聚糖(GAG)释放到培养基中的量。此外，在加载的试件的最上部区域积累了大量的GAG。这些结果可能表明，纯滑动负荷上调了培养标本最上部细胞外基质的生物合成，并可能阐明了在自然关节软骨表面区发现的富含蛋白多糖的层，它将在关节润滑中发挥重要作用。此外，还对培养软骨细胞-琼脂糖凝胶标本的材料转运特性进行了实验评价，以了解支架材料对培养软骨细胞的营养供应和细胞外基质分子在标本内的扩散的影响。在摩擦试验中还检测了蛋白质分子的润滑能力，以判断天然和再生软骨组织的边界润滑机制。较少

Articular cartilage is one of the unique and interesting soft tissues since it covers articulating surfaces of diarthrodial joints and plays an important role as "bearing" to achieve smooth joint movements. However, the detailed mechanism which governs the establishing process of the sophisticated tribological functions on the cartilage surface has not been clarified yet The purpose of this research project has been to investigate the developing process of functional cartilage tissue structure for the joint lubrication by the metabolic response of chondrocytes to the mechanical loadings experienced during the joint movement.It is well recognized that chondrocytes embedded in cartilage tissue can sense the mechanical stress and strain applied to the tissue. The chondrocytes subsequently regulate their metabolism through the mechanotransduction pathways and maintain the functional cartilage tissue structure. In this study, we have developed a rolling-sliding friction loading machine whic … More h can experimentally reproduce tribological stimulations, such as compressive strain, shear strain and fluid shear, exerted on the cartilage surface by frictional force during joint articulation. The loading machine was installed in CO_2 incubator and used to apply the tribological stimulation to chondrocytes being cultured three dimensionally within agarose gel Then, the effects of the tribological stimulations on the biosynthesis of extracellular matrix by chondrocytes and development of tissue structure were examined.Chondrocytes-agarose specimens were first culture under static condition for three days. Then, pure sliding was applied to the specimen surfaces by Pyrex glass rollers during 2 hours, twice a day for 5 days. Results indicated that the amount of glycosaminoglycan (GAG) released to the culture medium was increased by applying the pure sliding. Moreover, significant amount of GAG was accumulated within the uppermost region of the loaded specimens. These results might be indicating that the loading of pure sliding up-regulated the biosynthesis of extracellular matrix within the uppermost region of cultured specimens and might elaborate the proteoglycan-rich layer which had been identified within the surface region of natural articular cartilage and would be playing the important role in the joint lubrication. In addition, characteristics of the material transport within the cultured chondrocytes-agarose specimen was evaluated experimentally to understand the effect of scaffold materials on the nutrient supply to cultured chondrocytes and the diffusion of extracellular matrix molecules within the specimens. The lubrication ability of protein molecules was also examined in the friction test to estimate the boundary lubrication mechanism of natural and re-generated cartilage tissue. Less