Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, 48109, USA.
Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI, 48109, USA.
Sci Rep. 2018 Aug 28;8(1):12977. doi: 10.1038/s41598-018-30939-z.
Mechanical forces play critical roles in influencing human embryonic stem cell (hESC) fate. However, it remains largely uncharacterized how local mechanical forces influence hESC behavior in vitro. Here, we used an ultrasound (US) technique, acoustic tweezing cytometry (ATC), to apply targeted cyclic subcellular forces to hESCs via integrin-bound microbubbles (MBs). We found that ATC-mediated cyclic forces applied for 30 min to hESCs near the edge of a colony induced immediate global responses throughout the colony, suggesting the importance of cell-cell connection in the mechanoresponsiveness of hESCs to ATC-applied forces. ATC application generated increased contractile force, enhanced calcium activity, as well as decreased expression of pluripotency transcription factors Oct4 and Nanog, leading to rapid initiation of hESC differentiation and characteristic epithelial-mesenchymal transition (EMT) events that depend on focal adhesion kinase (FAK) activation and cytoskeleton (CSK) tension. These results reveal a unique, rapid mechanoresponsiveness and community behavior of hESCs to integrin-targeted cyclic forces.
机械力在影响人类胚胎干细胞（hESC）命运方面起着至关重要的作用。然而，局部机械力如何影响体外 hESC 的行为在很大程度上仍未得到描述。在这里，我们使用超声（US）技术，即声镊细胞术（ATC），通过整合素结合的微泡（MB）将靶向循环亚细胞力施加到 hESC 上。我们发现，ATC 介导的循环力施加到菌落边缘附近的 hESC 30 分钟，会立即引起整个菌落的全局反应，这表明细胞-细胞连接在 hESC 对 ATC 施加力的机械响应中的重要性。ATC 的应用会产生更大的收缩力，增强钙活性，并降低多能性转录因子 Oct4 和 Nanog 的表达，从而迅速启动 hESC 分化，并出现特征性的上皮-间充质转化（EMT）事件，这依赖于粘着斑激酶（FAK）的激活和细胞骨架（CSK）张力。这些结果揭示了 hESC 对整合素靶向循环力的独特、快速的机械响应和群体行为。
