Microfabricated Physical Spatial Gradients for Investigating Cell Migration and Invasion Dynamics

Abstract

We devise a novel assay that introduces micro-architectures into highly confining microchannels to probe the decision making processes of migrating cells. The conditions are meant to mimic the tight spaces in the physiological environment that cancer cells encounter during metastasis within the matrix dense stroma and during intravasation and extravasation through the vascular wall. In this study we use the assay to investigate the relative probabilities of a cell 1) permeating and 2) repolarizing (turning around) when it migrates into a spatially confining region. We observe the existence of both states even within a single cell line, indicating phenotypic heterogeneity in cell migration invasiveness and persistence. We also show that varying the spatial gradient of the taper can induce behavioral changes in cells, and different cell types respond differently to spatial changes. Particularly, for bovine aortic endothelial cells (BAECs), higher spatial gradients induce more cells to permeate (60%) than lower gradients (12%). Furthermore, highly metastatic breast cancer cells (MDA-MB-231) demonstrate a more invasive and permeative nature (87%) than non-metastatic breast epithelial cells (MCF-10A) (25%). We examine the migration dynamics of cells in the tapered region and derive characteristic constants that quantify this transition process. Our data indicate that cell response to physical spatial gradients is both cell-type specific and heterogeneous within a cell population, analogous to the behaviors reported to occur during tumor progression. Incorporation of micro-architectures in confined channels enables the probing of migration behaviors specific to defined geometries that mimic in vivo microenvironments.

Focal adhesion kinase is involved in the migration of human osteosarcoma cells

“…In 1977, Fidler and Kripke (9) put forward the concept of heterogeneity as the basis of tumor migration. From then on, it was realized that primary malignant tumor cells exhibit heterogeneity (10). Within a tumor, the biological characteristics and metastatic behaviors of various subgroups are not identical.…”

“…FAK is a widely-expressed, non-receptor protein tyrosine kinase located in the cytoplasm. Phosphorylation of FAK mediates signaling events, is widely involved in various biological processes within cells, and contributes to tumor progression, including invasion, metastasis and angiogenesis (8)(9)(10)(11). FAK is closely associated with the migration of malignant cells.…”

The Migration of Cancer Cells in Gradually Varying Chemical Gradients and Mechanical Constraints

“…The advantages of such devices include the use of smaller amounts of reagents, time-lapsed observation of cell migration and quantitative assessment of cell migration. Mak et al [58] demonstrated that a physical gradient with increasing mechano-stress device produced a difference in the migratory behaviors of breast cancer cells, because of the tapered channels.…”

“…The result is shown in Figure 6. The outcomes provided by Mak et al [58] indicated that physical gradients led to distinctive migration patterns among normal and malignant cells. However, our results indicated that chemical gradients generated by EGF in the channels led to the migration of the normal, as well as malignant cells into the tapered channels.…”

“…However, the effects of physical stress signaling in cell migration patterns still remain largely unclear. The most recent study by Mak et al [58] took into consideration the effect of physical spatial gradients. Their study provided direct evidence that physical stresses could lead to changes in migration patterns of MCF10A, a normal breast cell line, and MDAMB231, a malignant breast cancer cell line.…”