Sun Tao, Yan Zedong, Cai Jing, Shao Xi, Wang Dan, Ding Yuanjun, Feng Ying, Yang Jingyue, Luo Erping, Feng Xue, Jing Da
Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
Department of Diagnosis, College of Basic Medicine, Shaanxi University of Chinese Medicine, Xianyang, China.
Cell Biol Int. 2020 Jan;44(1):216-228. doi: 10.1002/cbin.11221. Epub 2019 Sep 4.
Diabetic patients exhibit significant bone deterioration. Our recent findings demonstrate that mechanical vibration is capable of resisting diabetic bone loss, whereas the relevant mechanism remains unclear. We herein examined the effects of mechanical vibration on the activities and functions of osteocytes (the most abundant and well-recognized mechanosensitive cells in the bone) exposed to high glucose (HG). The osteocytic MLO-Y4 cells were incubated with 50 mM HG for 24 h, and then stimulated with 1 h/day mechanical vibration (0.5 g, 45 Hz) for 3 days. We found that mechanical vibration significantly increased the proliferation and viability of MLO-Y4 cells under the HG environment via the MTT, BrdU, and Cell Viability Analyzer assays. The apoptosis detection showed that HG-induced apoptosis in MLO-Y4 cells was inhibited by mechanical vibration. Moreover, increased cellular area, microfilament density, and anisotropy in HG-incubated MLO-Y4 cells were observed after mechanical vibration via the F-actin fluorescence staining. The real-time polymerase chain reaction and western blotting results demonstrated that mechanical vibration significantly upregulated the gene and protein expression of Wnt3a, β-catenin, and osteoprotegerin (OPG) and decreased the sclerostin, DKK1, and receptor activator for nuclear factor-κB ligand (RANKL) expression in osteocytes exposed to HG. The enzyme-linked immunosorbent assay assays showed that mechanical vibration promoted the secretion of prostaglandin E and OPG, and inhibited the secretion of tumor necrosis factor-α and RANKL in the supernatant of HG-treated MLO-Y4 cells. Together, this study demonstrates that mechanical vibration improves osteocytic architecture and viability, and regulates cytokine expression and secretion in the HG environment, and implies the potential great contribution of the modulation of osteocytic activities in resisting diabetic osteopenia/osteoporosis by mechanical vibration.
糖尿病患者表现出明显的骨质恶化。我们最近的研究结果表明，机械振动能够抵抗糖尿病性骨质流失，但其相关机制仍不清楚。我们在此研究了机械振动对暴露于高糖（HG）环境下的骨细胞（骨中最丰富且公认的机械敏感细胞）的活性和功能的影响。将骨细胞系MLO-Y4细胞与50 mM HG孵育24小时，然后每天用1小时的机械振动（0.5 g，45 Hz）刺激3天。我们发现，通过MTT、BrdU和细胞活力分析仪检测，机械振动在HG环境下显著提高了MLO-Y4细胞的增殖和活力。凋亡检测表明，机械振动抑制了HG诱导的MLO-Y4细胞凋亡。此外，通过F-肌动蛋白荧光染色观察到，机械振动后HG孵育的MLO-Y4细胞的细胞面积、微丝密度和各向异性增加。实时聚合酶链反应和蛋白质印迹结果表明，机械振动显著上调了暴露于HG的骨细胞中Wnt3a、β-连环蛋白和骨保护素（OPG）的基因和蛋白表达，并降低了硬化蛋白、DKK1和核因子κB受体激活剂配体（RANKL）的表达。酶联免疫吸附测定表明，机械振动促进了前列腺素E和OPG的分泌，并抑制了HG处理的MLO-Y4细胞上清液中肿瘤坏死因子-α和RANKL的分泌。总之，本研究表明机械振动改善了骨细胞结构和活力，并在HG环境中调节细胞因子的表达和分泌，这意味着通过机械振动调节骨细胞活性在抵抗糖尿病性骨质减少/骨质疏松方面可能具有巨大贡献。
