Group of Ionic Mechanisms of Cell Signaling, Institute of Cytology of the Russian Academy of Sciences, St-Petersburg, Russia.
Higher School of Software Engineering, Institute of Computer Science and Technology, Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia.
PLoS One. 2021 Nov 30;16(11):e0260727. doi: 10.1371/journal.pone.0260727. eCollection 2021.
The actin cytoskeleton is indispensable for the motility and migration of all types of cells; therefore, it plays a crucial role in the ability of the tissues to repair. Mesenchymal stem cells are intensively used in regenerative medicine, but usually relatively low percent of transplanted cells reaches the injury. To overcome this evident limitation, researchers try to enhance the motility and migration rate of the cells. As one of the approaches, co-cultivation and preconditioning of stem cells with biologically active compounds, which can cause actin cytoskeleton rearrangements followed by an increase of migratory properties of the cells, could be applied. The observed changes in F-actin structure induced by the compounds require quantitative estimation, and measurement of fluorescence intensity of the F-actin image captured by various microscopic techniques is commonly used nowadays. However, this approach could not always accurately detect the observed changes in the shape and structure of actin cytoskeleton. At this time, the image of F-actin has an irregular geometric pattern, and thus could be considered and characterized as a fractal object. To quantify the re-organization of cellular F-actin in terms of fractal geometry Minkovsky's box-counting method is suitable, but it is not widely used nowadays. We modified and improved the previously described method for fractal dimension measurement, and successfully applied it for the quantification of the F-actin structures of human mesenchymal stem cells.
细胞骨架对于所有类型细胞的运动和迁移都是必不可少的；因此，它在组织修复能力中起着至关重要的作用。间充质干细胞在再生医学中被广泛应用，但通常只有相对较低比例的移植细胞到达损伤部位。为了克服这一明显的局限性，研究人员试图提高细胞的运动和迁移率。作为一种方法，可以应用共培养和用具有生物活性的化合物预处理干细胞，这些化合物可以引起细胞骨架肌动蛋白的重排，从而增加细胞的迁移特性。观察到的化合物诱导的 F-肌动蛋白结构的变化需要定量估计，并且目前常用各种显微镜技术捕获的 F-肌动蛋白图像的荧光强度测量来进行定量估计。然而，这种方法并不总是能够准确地检测到肌动蛋白细胞骨架的形状和结构的观察到的变化。此时，F-肌动蛋白的图像具有不规则的几何图案，因此可以被视为分形物体。为了从分形几何的角度量化细胞 F-肌动蛋白的重排，Minkowski 的盒子计数法是合适的，但目前它并不广泛使用。我们对以前描述的分形维数测量方法进行了修改和改进，并成功地将其应用于人骨髓间充质干细胞的 F-肌动蛋白结构的定量。
