Steinmeyer J, Ackermann B, Raiss R X
Department of Pharmacology and Toxicology, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany.
Osteoarthritis Cartilage. 1997 Sep;5(5):331-41. doi: 10.1016/s1063-4584(97)80037-4.
The aim of this study was to evaluate systematically the effect of tissue load, its amplitude, time of intermittence and duration of loading on the biosynthesis and release of fibronectin by intermittently loaded mature bovine articular cartilage explants.
Cyclic compressive pressure was introduced using a sinusoidal waveform of 0.5 Hz-frequency with a peak stress of 0.1, 0.5 or 1.0 MPa for a period of 10 s followed by an unloaded period lasting 10, 100 or 1000 s. Fibronectin and total proteins were radiolabeled with 10 microCi/ml [3H]-phenylalanine during the final 18 h of the 1, 3 or 6 day experiments. The content of endogenous fibronectin was determined using enzyme-linked immunosorbant assay (ELISA), whereas the viability of explants was measured using sections of cartilage explants stained with fluorescein diacetate and propidium iodide. The deformation of loaded explants was determined using a load-displacement transducer system.
The mechanical factor time of intermittence significantly altered the synthesis and release of fibronectin by cartilage explants, whereas the tested range of load magnitudes, as well as the duration of loading, seemed to be of subordinate importance. Loading affected the viability of the superficial zone in the cartilage, whereas the chondrocytes of the intermediate and deep zone remained viable. The compression of loaded explants was dependent on the magnitude of stress, as well as on the duration of unloading between each loading cycle. Synthesis of fibronectin, the retention of newly synthesized fibronectin within the extracellular matrix, and the portion of newly synthesized proteins that were fibronectin was significantly increased in cartilage explants which were cyclically compressed with 0.5 MPa for 10 s followed by a period of unloading lasting 100 s.
Previous studies reporting that cartilage explants of human and animal osteoarthritic joints synthesize and retain elevated amounts of fibronectin imply that in our experiments mechanical stimuli can induce a fibronectin metabolism in vitro which mimics some of the osteoarthritic characteristics.
本研究旨在系统评估组织负荷、其幅度、间歇时间和加载持续时间对间歇性加载的成熟牛关节软骨外植体中纤连蛋白生物合成和释放的影响。
使用频率为0.5Hz的正弦波形引入循环压缩压力，峰值应力为0.1、0.5或1.0MPa，持续10秒，随后是持续10、100或1000秒的无负荷期。在1、3或6天实验的最后18小时内，用10微居里/毫升[3H]-苯丙氨酸对纤连蛋白和总蛋白进行放射性标记。使用酶联免疫吸附测定（ELISA）测定内源性纤连蛋白的含量，而使用用荧光素二乙酸酯和碘化丙啶染色的软骨外植体切片测量外植体的活力。使用负荷-位移传感器系统测定加载外植体的变形。
机械因素间歇时间显著改变软骨外植体中纤连蛋白的合成和释放，而测试的负荷幅度范围以及加载持续时间似乎次要。加载影响软骨表层区域的活力，而中层和深层区域的软骨细胞保持活力。加载外植体的压缩取决于应力大小以及每个加载周期之间的卸载持续时间。在用0.5MPa循环压缩10秒然后持续100秒的卸载期的软骨外植体中，纤连蛋白的合成、新合成的纤连蛋白在细胞外基质中的保留以及新合成蛋白质中纤连蛋白的比例显著增加。
先前的研究报告称，人类和动物骨关节炎关节的软骨外植体合成并保留了大量的纤连蛋白，这意味着在我们的实验中，机械刺激可以在体外诱导一种模仿某些骨关节炎特征的纤连蛋白代谢。
