Introduction

Mechanical stimulation is important for maintaining cartilage function. We used a loading device to exert rolling-sliding mechanical stimulation on cartilage preserved in vitro to investigate cartilage viability and the involved mechanisms.

Methods

Osteochondral grafts from pig knees were randomly classified into loading and control groups. The loading group cartilage was subjected to cycles of mechanical stimulation with specified frequency/time/pressure combinations every 3 days; Then the DMEM was refreshed, and the cartilage was preserved in vitro. The control group cartilage was preserved in DMEM throughout the process and was changed every 3 days. On days 14 and 28, the chondrocyte survival rate, histology, and Young’s modulus of the cartilage were measured. Western blots were performed after 2 h of loading to evaluate the protein expression.

Results

The loading group showed a significantly higher chondrocyte survival rate, proteoglycan and type II collagen content, and Young’s modulus than did the control group on day 14, but no statistically significant differences were found on day 28. After two hours of the loading, the phosphorylation levels of MEK and ERK1/2 increased, and the expression of caspase-3, cleaved caspase-3 and bax decreased.

Conclusion

These results suggest that periodic rolling-sliding mechanical stimulation can increase cartilage vitality in 2 weeks; a possible mechanism is that mechanical stimulation activates the MEK/ERK signalling pathway, thus inhibiting apoptotic protein expression. This loading preservation scheme could be used by cartilage tissue banks to improve cartilage preservation in vitro and enhance the quality of cartilage repair.

中文翻译：

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滚动滑动机械刺激对体外保存软骨的影响。

介绍

机械刺激对于维持软骨功能很重要。我们使用加载装置对体外保存的软骨施加滚动滑动机械刺激，以研究软骨活力和相关机制。

方法

来自猪膝的骨软骨移植物被随机分为负荷组和对照组。负荷组软骨每 3 天以指定的频率/时间/压力组合进行机械刺激循环；然后刷新DMEM，体外保存软骨。对照组软骨全程保存在DMEM中，每3天更换一次。在第 14 天和第 28 天，测量软骨的软骨细胞存活率、组织学和杨氏模量。加载 2 小时后进行蛋白质印迹以评估蛋白质表达。

结果

加载组在第 14 天的软骨细胞存活率、蛋白多糖和 II 型胶原含量、杨氏模量均显着高于对照组，但在第 28 天差异无统计学意义。加载两小时后，磷酸化MEK和ERK1/2水平升高，caspase-3、cleaved caspase-3和bax的表达降低。

结论

这些结果表明，周期性滚动滑动机械刺激可以在 2 周内增加软骨活力；一个可能的机制是机械刺激激活 MEK/ERK 信号通路，从而抑制凋亡蛋白的表达。这种加载保存方案可用于软骨组织库，以改善体外软骨保存并提高软骨修复质量。