Novel Microfabricated Systems to Elucidate the Role of Anisotropic Stiffness in the Tumor Microenvironment

Cancer is the second leading cause of death in women and late stage (metastatic) cancers have abysmal survival rates compared to early stage regional cases (27% vs 86%). As a tumor grows, the surrounding extracellular matrix (ECM) is reorganized into a dense, collagen rich matrix. The new matrix of aligned collagen fibers provides unique mechanical cues such as anisotropic stiffness and contact guidance. Matrix turnover also constricts local vasculature and restricts delivery of key nutrients and signaling molecules to malignant cells to outside the tumor creating a chemotactic gradient from outside to inside. In this work, we developed a novel substrate composed of circular and oval cross section PDMS micropillars to study the effect of anisotropic mechanical cues on cell behavior. To prove that cells sense the mechanical properties of their surroundings through force, we downregulated (Y-27632 and blebbistatin) and upregulated (MDA-MB-231 conditioned media) traction force and observed that fibroblasts (NIH-3T3 and adipose derived stem cells (ASC)) feel the mechanical properties of their surroundings by applying force; and downregulating force disrupts mechanosensing. Second, we developed a novel multi-cue microfluidic assay to simulate both biomechanical and biochemical cues of the tumor microenvironment concurrently. NIH-3T3s were used to demonstrate that migration is primarily influenced by TACS mimicking mechanical cues and chemotactic gradients failed to alter migration characteristics significantly. We conclude that mechanical cues dominate chemotactic cues in directed migration