Menisci of the rabbit knee require mechanical loading to maintain homeostasis: cyclic hydrostatic compression in vitro prevents derepression of catabolic genes
Menisci of the rabbit knee require mechanical loading to maintain homeostasis: cyclic hydrostatic compression in vitro prevents derepression of catabolic genes
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DOI：
10.1007/s00776-005-0912-x
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发表时间：
2005-07-01
影响因子：
1.7
通讯作者：
Hart, DA
中科院分区：
文献类型：
--
作者：
Natsu-Ume, T;Majima, T;Hart, DA
本研究的目的是研究将半月板从体内负荷环境中移除对基因表达模式的影响，并确定体外负荷是否能维持组织的体内表型。体外培养兔单腿外侧和内侧半月板外植体，在1 MPa、0.5 Hz的间歇循环静水压力（CHP）下培养1分钟，休息时间14分钟（培养4小时）。对侧半月板在大气压下孵育4小时。另一组兔的双腿半月板立即冷冻，产生反映体内mRNA水平的时间零值。从所有组中分离总RNA，并对相关基因子集（基质分子、细胞因子、蛋白酶和抑制剂、酶）进行逆转录聚合酶链反应分析。发现MMP-1， MMP-3的mRNA水平。与零时间对照组相比，在非负荷条件下培养的组织中，半月板两侧的TIMPs、iNOS、COX-2、白细胞介素-1 β和内侧半月板的白细胞介素-6显著升高。半月板注射CHP可显著阻止几乎所有指示分子mRNA水平的增加。相比之下，胶原、biglycan、MMP-13和TIMP-4的mRNA水平在时间零值与非加载或加载条件下均无显著差异。这些研究表明，将兔半月板从其正常的体内机械环境中移除，会导致一组可能介导分解代谢活动的有效效应分子的明显上调，而体外CHP可以在很大程度上阻止这种明显的上调。
Background The purpose of this study was to examine the influence of removing menisci from their in vivo loading environment on gene expression patterns and to determine whether in vitro loading can maintain the tissues in their in vivo phenotype.Methods. Lateral and medial rabbit meniscal explants from one leg were cultured in vitro and subjected to intermittent cyclic hydrostatic pressure (CHP) of 1 MPa at 0.5 Hz for 1 min and a rest period of 14 min (4 h of culture). The contralateral menisci were incubated at atmospheric pressure for 4 h. Menisci from both legs of another set of rabbits were frozen immediately to yield time zero values reflective of in vivo mRNA levels. Total RNA was isolated from all groups and processed for reverse transcription-polymerase chain reaction analysis for a subset of relevant genes (matrix molecules, cytokines, proteinases and inhibitors, enzymes).Results. It was found that mRNA levels for MMP-1, MMP-3. TIMPs, iNOS, COX-2, interleukin-1 beta in both menisci, and interleukin-6 in medial menisci were significantly elevated in tissues cultured under nonloading conditions compared to the time zero controls. Subjecting menisci to CHP significantly prevented these increases in mRNA levels for nearly all of the indicated molecules. In contrast, there were no significant differences in mRNA levels for collagens, biglycan, MMP-13, or TIMP-4 between the time zero values and those cultured under either nonloading or loading conditions.Conclusions. These studies demonstrate that removing rabbit menisci from their normal in vivo mechanical environment leads to an apparent up-regulation of a subset of potent effector molecules that could mediate catabolic activities, and that in vitro CHP can largely prevent this apparent up-regulation.