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.
Bibliographical noteFunding Information:
P.P.P. was supported by a Research Scholar Grant, RSG-14-171-01-CSM from the American Cancer Society. This work was also supported by the NIH (R01CA181385, U54CA210190 University of Minnesota Physical Sciences in Oncology Center to P.P.P.), the UMN College of Science and Engineering, the Masonic Cancer Center, the UMN Institute for Engineering in Medicine, and the Randy Shaver Research and Community Fund (P.P.P.). A.R. is supported by a UMN Doctoral Dissertation Fellowship. The content of this work is solely the responsibility of the authors and does not necessarily represent the official views of the NIH or other funding agencies.
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