Department of Physical Medicine and Rehabilitation, University of Pittsburgh, 3471 5th Avenue, Suite 201, Pittsburgh, Pennsylvania 15213, USA.
J Orthop Res. 2011 Aug;29(8):1275-83. doi: 10.1002/jor.21388. Epub 2011 Feb 24.
As clinical evidence suggests that mechanical forces can have both reparative and traumatic effects on the spine, we investigated responses to different magnitudes, frequencies, and durations of applied tensile strain in an in vitro system. We examined the interactions of inflammatory and mechanical stimuli on cells isolated from the annulus fibrosus. Rabbit annulus fibrosus fibrochondrocytes were cultured in the presence or absence of an inflammatory stimulus. Cells were exposed to various magnitudes and frequencies of tensile strain for 4 or 24 h, and mRNA expression of catabolic mediators of inflammation and matrix degradation was measured by quantitative real time PCR and compared to control cells. Conditioned media were analyzed for matrix metalloprotease activity and production of prostaglandin E(2) . Application of low magnitudes and frequencies of tensile strain resulted in down-regulation of catabolic mediators, particularly under inflammatory stress. However, loss of this protective effect was observed at higher frequency and magnitude, and after prolonged duration. These in vitro data confirm the existence of magnitude, frequency, and duration based effects, which determine biochemical response of disc tissue resulting in either anti- or pro-catabolic outcomes. This may help to explain the beneficial effects of motion-based therapies as well as the destructive effect of traumatic levels of applied strain.
由于临床证据表明机械力对脊柱既有修复作用，也有创伤作用，我们在体外系统中研究了不同大小、频率和持续时间的拉伸应变的反应。我们研究了炎症和机械刺激对从纤维环分离的细胞的相互作用。在存在或不存在炎症刺激的情况下，将兔纤维环纤维软骨细胞进行培养。将细胞暴露于不同大小和频率的拉伸应变 4 或 24 小时，并通过实时定量 PCR 测量炎症和基质降解的分解代谢介质的 mRNA 表达，并与对照细胞进行比较。分析条件培养基中基质金属蛋白酶活性和前列腺素 E2 的产生。应用低大小和频率的拉伸应变导致分解代谢介质的下调，特别是在炎症应激下。然而，在更高的频率和幅度下，以及在更长的持续时间后，这种保护作用会丧失。这些体外数据证实了大小、频率和持续时间的影响的存在，这些影响决定了椎间盘组织的生化反应，从而导致抗或促分解代谢的结果。这可能有助于解释基于运动的治疗的有益效果，以及应用应变的创伤水平的破坏性影响。
