A Microfluidic Device to Characterize the Effect of Orthogonal Chemical Gradients on 3D Cancer Cell Migration

Once a primary tumor has metastasized to another location in a cancer patient, there is approximately a 20% chance of survival. In order to prevent cancer metastasis in the future, it is necessary to understand how cancer cells migrate from a primary tumor to the circulatory system and from the circulatory system to a secondary metastatic site. Within the tumor environment, cancer cells are subjected to competing gradients including chemicals (chemotaxis), extracellular matrix proteins (hapotaxis), and variations in matrix stiffness (durotaxis) which results in the directed migration of cells. Highly metastatic strains of breast cancer, such as the triple negative cell line MDA-MB-231, will chemotax towards certain chemoattractants such as SDF-1α and EGF. To explore this phenomenon, we have fabricated a microfluidic device that creates a “flow-free” chemical gradient within a chamber of cells seeded in a 3D collagen matrix. The chemical gradient is formed by the diffusion of chemoattractant within an agarose hydrogel using a three-channel microfluidic device composed of PDMS imprinted with three parallel channels including a source channel, a middle flow-free cell channel, and a sink channel. While the chemotactic response of MDA-MB-231 cells to gradients of either SDF-1α or EGF have been characterized, there is little known about how these cells respond to competing gradients or combinations of these chemoattractants. To create an environment with multiple gradients that better replicates in vivo conditions, we designed a second microfluidic device capable of inducing parallel or orthogonal chemical gradients by modifying the initial design to include two source channels, two sink channels, and a middle flow-free cell channel in the shape of a square. This device has the capability to study how cancer cells respond to multiple gradients as opposed to singular gradients. The gradients produced by the device have been simulated using COMSOL, and preliminary results will show MDA-MB-231 cells migrating within the orthogonal device.