Associate Professor of Physics
University of California, San Diego
Abstract: Directed migration in response to spatial non-uniformity of various external cues takes a variety of forms, such as chemo-, photo-, thermo-, aero-, and mechano-taxis. It is vital in the bacterial search for nutrients and energy and in the sporulation of social amoebae. In multicellular organisms, it is essential for development, inflammation, wound healing, and cancer metastasis. To study directed cell migration quantitatively, cells need to be presented with well-defined spatial distributions (gradients) of the cues and cellular responses need to be monitored at both behavioral and biochemical levels. I will discuss several projects, illustrating how these experimental challenges are addressed using microfluidics. We studied bacterial (E. coli) aero-taxis in various gradients of oxygen tension. Studies of chemo-taxis of social amoebae (D. discoideum) revealed the limits of their sensitivity and the roles of spatial and temporal cues in their gradient sensing. Experiments on primary human endothelial cells showed their migration responses to uniform and non-uniform hydrodynamic shear stress.