Fibril curvature is bioinstructive to attached cells. Similar to natural healthy tissues, an engineered extracellular matrix can be designed to stimulate cells to adopt desired phenotypes. To take full advantage of the curvature control in biomaterial fabrication methodologies, an understanding of the response to fibril subcellular curvature is required. In this work, we examined morphology, signaling, and function of human cells attached to electrospun nanofibers. We controlled curvature across an order of magnitude using nondegradable poly(methyl methacrylate) (PMMA) attached to a stiff substrate with flat PMMA as a control. Focal adhesion length and the distance of maximum intensity from the geographic center of the vinculin positive focal adhesion both peaked at a fiber curvature of 2.5 μm-1 (both ∼2× the flat surface control). Vinculin experienced slightly less tension when attached to nanofiber substrates. Vinculin expression was also more affected by a subcellular curvature than structural proteins α-tubulin or α-actinin. Among the phosphorylation sites we examined (FAK397, 576/577, 925, and Src416), FAK925 exhibited the most dependance on the nanofiber curvature. A RhoA/ROCK dependance of migration velocity across curvatures combined with an observation of cell membrane wrapping around nanofibers suggested a hybrid of migration modes for cells attached to fibers as has been observed in 3D matrices. Careful selection of nanofiber curvature for regenerative engineering scaffolds and substrates used to study cell biology is required to maximize the potential of these techniques for scientific exploration and ultimately improvement of human health.

中文翻译：

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评估粘着斑介导的亚细胞曲率传感对工程细胞外基质的反应。

原纤维曲率对附着细胞具有生物指导作用。与天然健康组织类似，工程细胞外基质可以被设计来刺激细胞采取所需的表型。为了充分利用生物材料制造方法中的曲率控制，需要了解对原纤维亚细胞曲率的响应。在这项工作中，我们检查了附着在电纺纳米纤维上的人体细胞的形态、信号传导和功能。我们将不可降解的聚甲基丙烯酸甲酯 (PMMA) 附着在硬质基材上，并以平坦的 PMMA 作为对照，将曲率控制在一个数量级上。粘着斑长度和距纽蛋白正粘着斑地理中心的最大强度距离均在纤维曲率为 2.5 μm-1 时达到峰值（均为平面对照的 ∼2 倍）。当连接到纳米纤维基材上时，纽蛋白所承受的张力稍小。与结构蛋白 α-微管蛋白或 α-肌动蛋白相比，纽蛋白表达更容易受到亚细胞曲率的影响。在我们检查的磷酸化位点（FAK397、576/577、925 和 Src416）中，FAK925 对纳米纤维曲率的依赖性最大。跨曲率迁移速度的 RhoA/ROCK 依赖性与对纳米纤维周围细胞膜包裹的观察相结合，表明了附着在纤维上的细胞的迁移模式的混合，正如在 3D 矩阵中观察到的那样。需要仔细选择用于研究细胞生物学的再生工程支架和基底的纳米纤维曲率，以最大限度地发挥这些技术在科学探索和最终改善人类健康方面的潜力。