Cell Migration and Breast Cancer Metastasis in Biomimetic Extracellular Matrices with Independently Tunable Stiffness

The mechanics of the extracellular matrix (ECM) have long been known to have important implications for cancer metastasis and cell migration. An atypical increase in tumor ECM stiffness occurs because of the heightened deposition of ECM proteins and increased crosslinking density of fibrillar collagen. This tissue stiffening is an essential contributor to disease progression; however, its precise role remains mostly unidentified. Recent advances in synthetic ECM analogs have enabled the concurrent exploration of the effects of crosslinking density, ligand concentrations, matrix stiffness, and pore sizes on tumor cell invasion. However, this convolution of parameters prevents an understanding of the independent contribution of each separate parameter to tumorigenesis. Here, the use of a precisely adjusted degree of methacryloyl substitution in gelatin-based hydrogel to capture the heterogeneity in cancer cell behavior in response to matrix stiffness is characterized and demonstrated. The proposed ECM model and biomimetic stiffening mechanism are used to produce complex 3D environments with physiological characteristics and independently tunable stiffness. Two populations of invasive and noninvasive human breast adenocarcinoma are embedded in these matrices and monitored by computer vision, enabling the reproduction and characterization of distinct cell migratory patterns as a result of differences in matrix stiffness and cell metastatic potential.