Background/purpose: Wharton’s jelly mesenchymal stem cells (WJMSCs) are well-known for use in nontissue-specific stem cell therapy. However, they can be a challenge for orthopedic used because they have low osteogenic differentiation ability. Several studies have found that static magnetic fields (SMFs) have positive effects on the osteogenesis of different stem cells. Nevertheless, whether SMFs have similar effects on WJMSC differentiation is unknown. Matrix vesicles are the critical characteristic of osteogenesis. Matrix vesicles serve as the initial site for physiological mineralization. Thus, the purpose of this study was to evaluate the effectiveness of a 0.4-T SMF on osteogenic differentiation and matrix vesicle secretion of WJMSCs.

Methods

In methodology, WJMSCs were treated with a 0.4-T SMF. The cell viability was tested using the MTT assay. For the osteogenic analysis, the alkaline phosphatase activity assay and alizarin red S staining were performed. The osteogenic-related gene expression of ALP, BMP-2, and Runx2 was examined using real-time polymerase chain reaction. Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy was used to analyze matrix vesicle secretion.

Results

The cell viability showed no significant difference between the SMF-treated group and the sham-exposed cells. However, the SMF-treated group exhibited significantly more mineralized nodule formation and higher ALP activity than their control counterparts (p < .05). The expressions of osteogenic-related markers, ALP, BMP-2, and Runx2, were also significantly higher in the SMF-treated WJMSCs. The scanning electron microscopy results showed much more matrix vesicle secretion in the SMF-treated cells than in the sham-treated cells. A mineralized sheath was noted in the SMF-treated cells, along with a sporadic accumulation of spherical mineralized deposits on the cell surface.

Conclusions

The results suggest that 0.4-T SMF treatment enhances the osteogenesis of WJMSCs at the early-to-middle stage of osteogenic differentiation by increasing the matrix vesicle secretion and mineralization.

中文翻译：

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静磁场增强了人脐带间充质干细胞通过基质囊泡分泌的成骨分化。

背景/目的：沃顿商学院的果冻间充质干细胞（WJMSC）用于非组织特异性干细胞疗法是众所周知的。但是，由于它们具有低的成骨分化能力，因此对于整形外科来说可能是一个挑战。多项研究发现，静磁场（SMF）对不同干细胞的成骨作用具有积极作用。然而，尚不清楚SMF是否对WJMSC分化具有相似的作用。基质囊泡是成骨的关键特征。基质囊泡是生理矿化的初始位置。因此，本研究的目的是评估0.4-T SMF对WJMSCs成骨分化和基质囊泡分泌的有效性。

方法

在方法上，WJMSC用0.4-T SMF处理。使用MTT测定法测试细胞活力。为了进行成骨分析，进行了碱性磷酸酶活性测定和茜素红S染色。使用实时聚合酶链反应检测ALP，BMP-2和Runx2的成骨相关基因表达。扫描电子显微镜结合能量色散X射线光谱法分析基质囊泡的分泌。

结果

SMF处理组和假手术暴露细胞之间的细胞活力没有显示出显着差异。然而，与对照组相比，经SMF处理的组表现出明显更多的矿化结节形成和更高的ALP活性（p  <.05）。在SMF处理的WJMSC中，成骨相关标志物ALP，BMP-2和Runx2的表达也明显更高。扫描电子显微镜结果显示，与经假手术处理的细胞相比，经SMF处理的细胞的基质囊泡分泌更多。在SMF处理过的细胞中发现了矿化的鞘，并且在细胞表面上散布了球形矿化的沉积物。

结论

结果表明0.4-T SMF处理通过增加基质囊泡的分泌和矿化作用，在成骨分化的早期至中期增强了WJMSCs的成骨性。