Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA.
Acta Biomater. 2013 May;9(5):6381-92. doi: 10.1016/j.actbio.2013.01.026. Epub 2013 Feb 1.
Human mesenchymal stem cell (hMSC) migration and recruitment play a critical role during bone fracture healing. Within the complex three-dimensional (3-D) in vivo microenvironment, hMSC migration is regulated through a myriad of extracellular cues. Here, we use a thiol-ene photopolymerized hydrogel to recapitulate structural and bioactive inputs in a tunable manner to understand their role in regulating 3-D hMSC migration. Specifically, peptide-functionalized poly(ethylene glycol) hydrogels were used to encapsulate hMSC while varying the crosslinking density, from 0.18±0.02 to 1.60±0.04 mM, and the adhesive ligand density, from 0.001 to 1.0 mM. Using live-cell videomicroscopy, migratory cell paths were tracked and fitted to a Persistent Random Walk model. It was shown that hMSC migrating through the lowest crosslinking density and highest adhesivity had more sustained polarization, higher migrating speeds (17.6±0.9 μm h(-1)) and higher cell spreading (elliptical form factor=3.9±0.2). However, manipulation of these material properties did not significantly affect migration persistence. Further, there was a monotonic increase in cell speed and spreading with increasing adhesivity that showed a lack of the biphasic trend seen in 2-D cell migration. Immunohistochemistry showed well-formed actin fibers and β1 integrin staining at the ends of stress fibers. This thiol-ene platform provides a highly tunable substrate to characterize 3-D hMSC migration that can be applied as an implantable cell carrier platform or for the recruitment of endogenous hMSC in vivo.
人骨髓间充质干细胞（hMSC）的迁移和募集在骨折愈合过程中起着关键作用。在复杂的三维（3-D）体内微环境中，hMSC 的迁移受到多种细胞外信号的调节。在这里，我们使用硫醇-烯光聚合水凝胶以可调节的方式再现结构和生物活性输入，以了解它们在调节 3-D hMSC 迁移中的作用。具体来说，使用肽功能化聚乙二醇水凝胶来包封 hMSC，同时改变交联密度，从 0.18±0.02 到 1.60±0.04 mM，以及粘附配体密度，从 0.001 到 1.0 mM。使用活细胞视频显微镜，跟踪迁移细胞路径并拟合到持续随机漫步模型。结果表明，通过最低交联密度和最高粘附性迁移的 hMSC 具有更持续的极化、更高的迁移速度（17.6±0.9 μm h(-1)）和更高的细胞扩展（椭圆形状因子=3.9±0.2）。然而，这些材料特性的操纵并没有显著影响迁移的持久性。此外，细胞速度和扩展随粘附性的增加呈单调增加，这表明在 2-D 细胞迁移中未见的双相趋势。免疫组织化学显示在应力纤维末端形成了良好的肌动蛋白纤维和 β1 整合素染色。这种硫醇-烯平台提供了一个高度可调的底物，用于表征 3-D hMSC 迁移，可作为可植入细胞载体平台或用于体内招募内源性 hMSC。
