Ibec Seminar. Amin Doostmohammadi
Multiscale dynamics and mechanics of the basement membrane in epithelial morphogenesis
Amin Doostmohammadi, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen, Denmark
Tissues must renew themselves throughout life. Cells divide to replace lost cells, while damaged or unfit cells must be removed without breaking the tissue. Here we show that mechanics builds a landscape that guides both processes.
We first look at how cells flow in a growing layer. Using Lagrangian coherent structures, we find attracting and repelling regions in the cell flow. These regions follow the stress hotspots in the tissue and predict where cells will be pushed out later. Cell motion alone can therefore reveal the mechanical state of the tissue.
Stress also decides where cells divide. In dense epithelia, cell division follows the direction of greatest stress. This replaces the classic long axis rule, which links division to cell shape. Each division relieves the stress that triggered it, which creates a feedback loop that keeps the tissue in balance. We call this the principal stress rule.
Mechanics also decides which cells survive. When two cell types meet, differences in force transmission decide the winner. Changing force transmission across cell junctions blocks the removal of dying cells, and some extruded cells survive and invade soft gels.
Together, these results show that a multicellular tissue steers its own renewal and removal through forces. The same landscape that places a cell also helps decide its fate. This view links active matter physics with tissue biology, and it suggests new ways to control tissue growth, repair, and the spread of cancer cells.
