Ray Arja, Slama Zachary M, Morford Rachel K, Madden Samantha A, Provenzano Paolo P
Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota; University of Minnesota Physical Sciences in Oncology Center, University of Minnesota, Minneapolis, Minnesota.
Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota.
Biophys J. 2017 Mar 14;112(5):1023-1036. doi: 10.1016/j.bpj.2017.01.007.
Directed cell migration by contact guidance in aligned collagenous extracellular matrix (ECM) is a critical enabler of breast cancer dissemination. The mechanisms of this process are poorly understood, particularly in 3D, in part because of the lack of efficient methods to generate aligned collagen matrices. To address this technological gap, we propose a simple method to align collagen gels using guided cellular compaction. Our method yields highly aligned, acellular collagen constructs with predictable microstructural features, thus providing a controlled microenvironment for in vitro experiments. Quantifying cell behavior in these anisotropic constructs, we find that breast carcinoma cells are acutely sensitive to the direction and extent of collagen alignment. Further, live cell imaging and analysis of 3D cell migration reveals that alignment of collagen does not alter the total motility of breast cancer cells, but simply redirects their migration to produce largely one-dimensional movement. However, a profoundly enhanced motility in aligned collagen matrices is observed for the subpopulation of carcinoma cells with high tumor initiating and metastatic capacity, termed cancer stem cells (CSCs). Analysis of the biophysical determinants of cell migration show that nuclear deformation is not a critical factor associated with the observed increases in motility for CSCs. Rather, smaller cell size, a high degree of phenotypic plasticity, and increased protrusive activity emerge as vital facilitators of rapid, contact-guided migration of CSCs in aligned 3D collagen matrices.
在排列整齐的胶原细胞外基质（ECM）中，通过接触导向实现的细胞定向迁移是乳腺癌扩散的关键因素。这一过程的机制尚不清楚，尤其是在三维环境中，部分原因是缺乏生成排列整齐的胶原基质的有效方法。为了弥补这一技术差距，我们提出了一种利用引导性细胞压实来排列胶原凝胶的简单方法。我们的方法可产生具有可预测微观结构特征的高度排列整齐的无细胞胶原构建体，从而为体外实验提供可控的微环境。通过量化这些各向异性构建体中的细胞行为，我们发现乳腺癌细胞对胶原排列的方向和程度极为敏感。此外，对三维细胞迁移的活细胞成像和分析表明，胶原的排列不会改变乳腺癌细胞的总运动性，而只是将其迁移重新定向，使其主要产生一维运动。然而，对于具有高肿瘤起始和转移能力的癌细胞亚群，即癌症干细胞（CSCs），在排列整齐的胶原基质中观察到其运动性显著增强。对细胞迁移的生物物理决定因素的分析表明，核变形并非与观察到的CSCs运动性增加相关的关键因素。相反，较小的细胞尺寸、高度的表型可塑性以及增加的突出活性，成为CSCs在排列整齐的三维胶原基质中快速、接触导向迁移的重要促进因素。
