The collaboration aimed to understand how the movement of each cell of a group determines mass migration, a mechanism intrinsic to processes such as tissue regeneration and cancer metastasis. “We had long suspected that each cell exerts force not only upon its extracellular matrix but also upon neighbouring cells,” explains IBEC group leader Xavier Trepat. Plithotaxis, which comes from the Greek plithos, meaning throng or swarm, describes what the scientists discovered when they devised a way to measure the forces that push and pull each cell alongside its neighbours in a chaotic ‘dance’, yet with the cell sheet moving along cooperatively in the desired direction. “When we think of collective processes in biology, we often imagine that the movement of each cell is perfectly synchronized with that of its neighbours, as if dancing a minuet,” adds Xavier. “By contrast, we found that this ‘dance’ is more like moshing: messy and violent.”
The image shows the cytoskeleton or ‘scaffold’ of a group of migrating epithelial cells (the epithelium is a membrane of one or more layers of cells that covers most of the surfaces in the body, including the organs). Some of the cells are highlighted using colour-coding to depict how differences in forces can exist within the sheet.
As cell migration, where groups of cells move long distances without losing their cohesiveness, is critical for tissues to be able to regenerate and, on the other hand, a major factor in the spread of cancer, the researchers’ work could lead to important insights into predicting the movement of cancer cells.
Image © Xavier Serra/IBEC. Source article: Trepat, X and Fredberg, J.J. (2011). Plithotaxis and emergent dynamics in collective cellular migration. Trends in Cell Biology, 21(11), 638-646