中文摘要：

将内皮细胞生长因子（VEGF）置于甲基纤维素碟中形成VEGF的浓度梯度分布,并将人脐带间充质干细胞（Mesenchymal stem cells,MSCs）于此浓度梯度中培养,观察VEGF能否诱导MSCs定向迁移。应用近场扫描光学显微术（Near-field scanning optical microscopy,NSOM）同时获取了VEGF诱导前后的MSCs的形貌和光学信息。结果表明,近场光学图观测到形貌图上所没有的黑色斑点,分析认为这些黑斑为细胞的黏着斑。近场光学图显示经过VEGF诱导后细胞的黏着斑数量明显增加。同时,对诱导前后干细胞的骨架蛋白进行免疫荧光标记并用共聚焦显微镜进行观察,结果表明细胞骨架由诱导前的无序状态转变为诱导后的有序状态,说明诱导后的干细胞处于迁移状态。光学超微结构图则显示了诱导后干细胞表面的光学细节比诱导前细胞大量增加,出现了大量直径约200 nm的光斑,这是由于细胞表面大量分泌黏附分子等蛋白分子引起的,这些结果为VEGF能够诱导MSCs进行定向迁移提供了实验依据和可视化证明。也表明NSOM不但能提供高分辨的光学分辨率,还可提供生物细胞精细结构的更深层次的光学信息。

英文摘要：

To investigate whether vascular endothelial growth factor（VEGF） could induce human mesenchymal stem cells（MSCs） to migrate directionally,methyl cellulose discs imbued with VEGF were placed in a dish to generate a concentration gradient of VEGF.MSCs were then placed in a given area with a defined distance from the methyl cellulose discs.Near-field scanning optical microscopy（NSOM） was used to obtain simultaneously the morphological and optical informations of MSCs before and after VEGF induction.Results showed that black spots were observed from the near-field images,but not from the morphological images.Analysis based on the imaging principles of near-filed optics demonstrated that these spots should be cell adhesion plaques.Near-field optical images also showed that the cell adhesion plaques increased markedly and optical details on the cell surface increased tremendously after induction.Immuno-fluorescent labeling technique was used to observe the transformation of cytoskeleton of MSCs from disordered to ordered arrangement after induced by VEGF.The result indicated that the cells migrated directionally.The data obtained demonstrate that NSOM can provide not only higher optical resolution,but also more detailed optical information for the fine structure of biological cells.