Suh J K, Baek G H, Arøen A, Malin C M, Niyibizi C, Evans C H, Westerhausen-Larson A
Department of Orthopaedic Surgery, University of Pittsburgh, PA 15213, USA.
Osteoarthritis Cartilage. 1999 Jan;7(1):71-80. doi: 10.1053/joca.1998.0163.
Experimental findings have suggested that the metabolic activities of articular cartilage can be influenced by mechanical stimuli. Our mathematical analysis predicted that cyclic compressive loading may create periods of intermittent sub-ambient hydrostatic pressure within the cartilage extracellular matrix. Based on this mathematical analysis, the present study was aimed to investigate whether the intermittent sub-ambient hydrostatic pressure, created in the cartilage extracellular matrix during cyclic compression, has a stimulative effect on the biosynthesis of chondrocytes.
In order to test this hypothesis, the present study developed a custom-designed sub-ambient pressure generator to subject a monolayer culture of chondrocytes to an intermittent sub-ambient pressure. Using this pressure generator, the monolayer chondrocyte culture system was analyzed for 35S-sulfate and 3H-proline incorporation rates for biosynthesis of proteoglycan and collagenous/noncollagenous protein molecules, respectively. Northern analyses for aggrecan and type II collagen mRNAs were also performed.
It was found that the intermittent sub-ambient pressure produced a 40% increase in proteoglycan and a 17% increase in non-collagenous protein synthesis during the pressurization period (P < 0.05). The collagenous protein synthesis was not affected by the intermittent sub-ambient pressure regimen used in this study. After the intermittent sub-ambient pressurization, the metabolic activities of the chondrocytes returned to normal (control level). The intermittent sub-ambient pressure also produced an increase in the mRNA signals for aggrecan. Therefore, we conclude that intermittent sub-ambient pressure may be one of the potential mechanical stimulators of chondrocytes in articular cartilage during dynamic compression.
实验结果表明，机械刺激可影响关节软骨的代谢活动。我们的数学分析预测，周期性压缩载荷可能会在软骨细胞外基质内产生间歇性低于环境静水压的时期。基于此数学分析，本研究旨在探讨在周期性压缩过程中软骨细胞外基质内产生的间歇性低于环境静水压是否对软骨细胞的生物合成具有刺激作用。
为了验证这一假设，本研究开发了一种定制设计的低于环境压力发生器，以使软骨细胞单层培养物受到间歇性低于环境压力的作用。使用该压力发生器，分别分析单层软骨细胞培养系统中用于蛋白聚糖生物合成的35S-硫酸盐掺入率和用于胶原/非胶原蛋白质分子生物合成的3H-脯氨酸掺入率。还进行了聚集蛋白聚糖和II型胶原mRNA的Northern分析。
发现间歇性低于环境压力在加压期间使蛋白聚糖合成增加了40%，非胶原蛋白质合成增加了17%（P<0.05）。本研究中使用的间歇性低于环境压力方案未影响胶原蛋白质合成。间歇性低于环境压力处理后，软骨细胞的代谢活动恢复正常（对照水平）。间歇性低于环境压力还使聚集蛋白聚糖的mRNA信号增加。因此，我们得出结论，间歇性低于环境压力可能是动态压缩过程中关节软骨软骨细胞的潜在机械刺激因素之一。
