Statistical mechanics of proliferation

Cell division is one of the most fundamental activities of life, yet the collective physics it generates has received far less attention than motility-driven active matter. Our main focus is to establish a rigorous statistical-physics description of proliferating multicellular systems as a distinct class of active matter. Growth and division break number and volume conservation, correlate cells that share a lineage, and generate anisotropic stresses — leading to genuinely new phenomena.

In growing three-dimensional spheroids we found a sharp motility-induced mixing transition: Below a threshold, growth-driven pressure confines cell lineages; above it, cells disperse and mix. We have also uncovered growth-driven phase separation between motile and proliferating cells, a mechanical fitness metric that decides competition in homeostatic tissue, and self-similar trajectory statistics in isovolumetric (embryo-like) division.

Understanding whether a tissue is mixed or confined has direct implications for tumor invasion, therapeutic access, and the design of cell therapies.