Symposium

Cell Migration and Pattern Formation Guided by Dynamic Microenvironments
Melody Ann Swartz
Swiss Federal Institute Of Technology, Lausanne (Epfl)
http://lmbm.epfl.ch/

Summary
We are interested in growth, trafficking and organization of cells, both in times of need, and when we first develop from the fertilized egg. Cells perceive the need to grow, and the direction of growth by sensing a gradient of chemical signals. If it is a signal that encourages growth, or migration, the cells sample their space and move towards higher and higher levels of that signal. Rather than the current model of an external source creating a chemical gradient, we now have proposed, and experimentally and computationally supported, a novel general model that suggests how the cells themselves generate these chemical gradients.

Blood circulates to all parts of the body in thinner and thinner capillaries. In the capillaries, fluid filters out to the tissue due to the pressure gradient between the inside and outside of the vessel walls. The lymphatic vessels take away fluids from the extremities back into the blood circulation. So in all tissues at all times, there is a very slow flow of fluids derived from pressure differentials generally between blood to lymphatic capillaries.

In our model, the cells generate a uniform distribution of signals in its immediate surroundings. These signals are directionally biased by virtue of the cells being situated in this slow flow environment. In other words, cells, while being the source of cues, at the same time “see” a gradient of directional cues. In this way, for example, lymphatic vessel precursor cells subtly “self-guide” themselves to where new vessels are needed, immune cells "find” their way into the circulation by "going with the flow”, and tumor cells use the same mechanism to metastasize. The story of this presentation is how cells respond to the very slow flow and generate the necessary directionality in chemical signals by remodeling their immediate environment.

Biography
Melody Swartz is an Assistant Professor of Bioengineering at the Swiss Federal Institute of Technology in Lausanne. She obtained her PhD in Chemical Engineering from MIT and conducted postdoctoral work at Harvard Medical School. She is interested in how cells integrate microenvironmental cues – both molecular and biomechanical - to signal, organize, and form functional patterns. Her lab has demonstrated a role for interstitial flow in lymphatic capillary organization, cell organization in tissue culture, and directed chemotaxis of cells towards lymphatics, which has implications in cancer metastasis and immune function.