UC San Diego

Cell migration is an important cellular process in many physiological events such as embryogenesis, wound healing, cancer metastasis, and inflammation. Chemotaxis is a process in which cells migrate in the direction of a chemical gradient. This process can be observed in the immune response, in which leukocytes will migrate from the vasculature into inflamed tissue. Advancements in fabrication technologies have lead to the development of many devices for studying in vitro chemotaxis. This thesis presents a hydrogel device that establishes a chemical gradient to study chemotaxis. The device creates the gradient using diffusion and maintains the stable, linear gradient using flow. The gradient profile was characterized by monitoring the diffusion of rhodamine to determine that a stable gradient can be established in 40 minutes. Differentiated HL-60 (dHL-60) cells were used as a model cell type to interrogate the capabilities of the device. These cells migrated in a directed manner when exposed to an fMLP gradient for 60 minutes with a mean CI of 0.6479. Several biochemical and mechanical experimental parameters, such as pre-activation of the dHL-60 cells and collagen gel concentration, can be further optimized to increase the chemotaxis response of the cells. This device enables the study of cells in 2D and 3D environments and was fabricated with readily available manufacturing tools – allowing for prototyping for new applications.