Department of Anatomy and Cell Biology, RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany.
Institute of Biological Information Processing: IBI-2, Forschungszentrum Jülich, 52425 Jülich, Germany.
Int J Mol Sci. 2020 Feb 6;21(3):1082. doi: 10.3390/ijms21031082.
Tenocytes are mechanosensitive cells intimately adapting their expression profile and hence, their phenotype to their respective mechanomilieu. The immunolocalization and expression intensity of tenogenic, anabolic and catabolic markers in tenocytes in response to in vitro mechanical loading have not been monitored by immunohistochemical staining (IHC). Thus, we investigated the association between IHC intensities, different stimulation frequencies, and tenogenic metabolism using a versatile mechanical stretcher. Primary tenocytes obtained from murine Achilles tendons were transferred to poly(dimethylsiloxane) (PDMS) elastomeric chamber. Chambers were cyclically stretched by 5% in uniaxial direction at a variation of tensile frequency (1 or 2 Hz) for 3 h. After stretching, cell physiology, IHC intensities of tendon-related markers, and protein level of the angiogenesis marker vascular endothelial growth factor (VEGF) were evaluated. Cell proliferation in tenocytes stimulated with 1 Hz stretch was significantly higher than with 2 Hz or without stretch, while 2 Hz stretch induced significantly reduced cell viability and proliferation with microscopically detectable apoptotic cell changes. The amount of scleraxis translocated into the nuclei and tenomodulin immunoreactivity of tenocytes treated with stretch were significantly higher than of non-stretched cells. The collagen type-1 expression level in tenocytes stretched at 1 Hz was significantly higher than in those cultivated with 2 Hz or without stretching, whereas the matrix metalloproteinase (MMP)-1 and MMP-13 immunoreactivities of cells stretched at 2 Hz were significantly higher than in those stimulated with 1 Hz or without stretching. The secreted VEGF-protein level of tenocytes stretched at 2 Hz was significantly higher than without stretching. Our IHC findings consistent with cell physiology suggest that appropriate stretching can reproduce in vitro short-term tenogenic anabolic/catabolic conditions and allow us to identify an anabolic stretching profile.
肌腱细胞是一种机械敏感性细胞,能够根据其所处的机械微环境来调整其表达谱和表型。目前尚未通过免疫组织化学染色(IHC)来监测体外机械加载对肌腱细胞中成肌腱、合成代谢和分解代谢标志物的免疫定位和表达强度。因此,我们使用一种多功能机械拉伸器研究了 IHC 强度、不同刺激频率与肌腱细胞合成代谢之间的关系。从小鼠跟腱中分离出原代肌腱细胞,转移到聚二甲基硅氧烷(PDMS)弹性室中。通过在单轴方向上以 5%的幅度循环拉伸,在 1 或 2 Hz 的不同拉伸频率下,将弹性室拉伸 3 小时。拉伸后,评估细胞生理学、肌腱相关标志物的 IHC 强度和血管生成标志物血管内皮生长因子(VEGF)的蛋白水平。1 Hz 拉伸刺激的肌腱细胞增殖明显高于 2 Hz 或无拉伸,而 2 Hz 拉伸诱导的细胞活力和增殖明显降低,显微镜下可见凋亡细胞变化。与未拉伸的细胞相比,经拉伸处理的肌腱细胞中硬蛋白向核内转移和肌腱调蛋白的免疫反应性明显更高。1 Hz 拉伸的肌腱细胞中胶原 I 型的表达水平明显高于 2 Hz 培养或无拉伸的细胞,而在 2 Hz 拉伸刺激下,细胞中基质金属蛋白酶(MMP)-1 和 MMP-13 的免疫反应性明显高于 1 Hz 刺激或无拉伸的细胞。2 Hz 拉伸的肌腱细胞分泌的 VEGF 蛋白水平明显高于无拉伸。我们的 IHC 发现与细胞生理学一致,表明适当的拉伸可以在体外再现短期的肌腱细胞合成代谢/分解代谢条件,并使我们能够确定一种合成代谢的拉伸特征。
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