Search

Physical and mechanical properties of extracellular matrix (ECM) have been proved to be crucial in the metastatic process. However, currently available studies on the interplay between ECM stiffness and cancer cell invasive behaviour are performed on planar assays, while the in vivo interaction takes place in three-dimensions. To take into consideration the ECM structural and mechanical complexity in the cell/structure interactions, we fabricated 3D microscaffolds through two-photon lithography (2PL) and tested how they are invaded by human colorectal adenocarcinoma (LS-174T) tumor cells, showing that it is possible to detect significant differences in cells/structure interaction when structural parameters are modified. In particular, both scaffold geometry and 2PL fabrication parameters were optimized to obtain 3D polymeric cylindrical structures with controlled Young's modulus and with linear stiffness gradients. The ability of LS-174T to migrate in the scaffolds was tested in different experimental conditions, including scaffolds functionalization and under β-catenin downregulation. It was observed that high Young's modulus scaffolds are always less invaded than softer ones, confirming the role of the 3D micro-environmental stiffness in mediating cells migration, including when specific functionalization or pharmacological treatments are performed.

Cells are highly dynamic elements, continuously interacting with the extracellular environment. Mechanical forces sensed and applied by cells are responsible for cellular adhesion, motility, and deformation, and are heavily involved in determining cancer spreading and metastasis formation. Cell/extracellular matrix interactions are commonly analyzed with the use of hydrogels and 3D microfabricated scaffolds. However, currently available techniques have a limited control over the stiffness of microscaffolds and do not allow for separating environmental properties from biological processes in driving cell mechanical behavior, including nuclear deformability and cell invasiveness. Herein, a new approach is presented to study tumor cell invasiveness by exploiting an innovative class of polymeric scaffolds based on two-photon lithography to control the stiffness of deterministic microenvironments in 3D. This is obtained by fine-tuning of the laser power during the lithography, thus locally modifying both structural and mechanical properties in the same fabrication process. Cage-like structures and cylindric stent-like microscaffolds are fabricated with different Young's modulus and stiffness gradients, allowing obtaining new insights on the mechanical interplay between tumor cells and the surrounding environments. In particular, cell invasion is mostly driven by softer architectures, and the introduction of 3D stiffness “weak spots” is shown to boost the rate at which cancer cells invade the scaffolds. The possibility to modulate structural compliance also allowed estimating the force distribution exerted by a single cell on the scaffold, revealing that both pushing and pulling forces are involved in the cell–structure interaction. Overall, exploiting this method to obtain a wide range of 3D architectures with locally engineered stiffness can pave the way for unique applications to study tumor cell dynamics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Cancer cell motility is one of the major events involved in metastatic process. Tumor cells that disseminate from a primary tumor can migrate into the vascular system and, being carried by the bloodstream, transmigrate across the endothelium, giving rise to a new tumor site. However, during the invasive process, tumor cells must pass through the extracellular matrix, whose structural and mechanical properties define the parameters of the migration process. Here, we propose 3D-complex cage-like microstructures, realized by two-photon (TP) direct laser writing (DLW), to analyze cell migration through pores significantly smaller than the cell nucleus. We found that the ability to traverse differently sized pores depends on the metastatic potential and on the invasiveness of the cell lines, allowing to establish a pore-area threshold value able to discriminate between non-tumorigenic and tumorigenic human breast cells.