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Active matter is matter driven out of equilibrium by its microscopic constituents. Common examples include the cytoskeleton of the cell, bacteria swimming in a fluid, or herds of wildebeest on the African planes. In these systems, the constituents create forces and motion driving the system out of equilibrium. But now imagine cells dividing or a tumor growing. Then activity does not enter the dynamics via the forces, but by material conservation. The material generates itself. In order to grow, cells must exert mechanical pressure on the neighboring tissue. In turn, mechanical stress influences growth and may play a role in cell competition. This insight has led to the notion of homeostatic pressure – the pressure exerted by a tissue in homeostasis. We use particle based computer simulations to model growing tissues. Surprisingly, we find that when cross interactions are taken into account tissues with different homeostatic pressure can coexist and the evolution can favor the weaker tissue, or even results in tumor heterogeneity.

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Jens Elgeti, FZ Jülich
Seminar Room 0.03, ETP
Contact: Joachim Krug