Sauerland K, Steinmeyer J
Orthopaedic Research Laboratories, Department of Orthopaedic Surgery, University Clinics Giessen and Marburg GmbH, Paul-Meimberg-Strasse 3, 35385 Giessen, Germany.
Osteoarthritis Cartilage. 2007 Dec;15(12):1403-9. doi: 10.1016/j.joca.2007.05.004. Epub 2007 Jun 18.
Alterations in the sulfation pattern of chondroitin sulfate (CS) chains of proteoglycans have been associated with aging and degeneration of articular cartilage. The purpose of the present study was to investigate systematically the effect of load amplitudes, frequencies and load durations of intermittently applied mechanical pressure on the sulfation of CS chains of cultured bovine articular cartilage explants.
Using a sinusoidal waveform of 0.5 Hz frequency, cyclic compressive pressure of 0.1-1.0 MPa was applied for 10s followed by a period of unloading lasting 10-1000 s. These intermittent loading protocols were repeated for a total duration of 1-6 days. Newly synthesized as well as endogenous CS chains were isolated, depolymerized and subsequently quantitated after fractionation by high-performance anion-exchange chromatography.
Increasing the mechanical demands on cartilage explants by elevating either the duration or the frequency of loading can significantly alter the fine structure of newly synthesized CS in that less chains terminate on galNAc4,6S and, in that simultaneously the ratio of the internal disaccharides DeltaDi6S to DeltaDi4S is increased. Similar results were obtained with explants being slightly mechanically challenged by low magnitudes of loads.
Our data show for the first time that intermittent loading of articular cartilage explants can significantly alter the sulfation pattern of the terminal CS residues as well as of the internal disaccharides. Furthermore, our results indicate that explants possess a physiological window of stress in which they are able to produce also a normal extracellular matrix.
蛋白聚糖硫酸软骨素（CS）链硫酸化模式的改变与关节软骨的衰老和退变有关。本研究的目的是系统研究间歇性施加机械压力的负荷幅度、频率和负荷持续时间对培养的牛关节软骨外植体CS链硫酸化的影响。
使用频率为0.5Hz的正弦波形，施加0.1 - 1.0MPa的循环压缩压力10秒，随后是持续10 - 1000秒的卸载期。这些间歇性加载方案重复进行1 - 6天的总时长。新合成的以及内源性CS链被分离、解聚，随后通过高效阴离子交换色谱分离后进行定量。
通过增加加载的持续时间或频率来提高对软骨外植体的机械需求，可显著改变新合成CS的精细结构，即较少的链在GalNAc4,6S处终止，同时内部二糖DeltaDi6S与DeltaDi4S的比例增加。对于受到低强度负荷轻微机械刺激的外植体，也获得了类似结果。
我们的数据首次表明，关节软骨外植体的间歇性加载可显著改变末端CS残基以及内部二糖的硫酸化模式。此外，我们的结果表明外植体具有一个生理应激窗口，在此窗口内它们也能够产生正常的细胞外基质。
