In this study, we demonstrate that physics describing how a droplet actively moves and wets a surface can also explain how clusters of cancer cells migrate from soft to stiffer environments. This discovery could help us understand how cancer cells spread throughout the body.
Cells move through the body for different purposes: to create new organs during embryonic development, to chase pathogens, and also to spread tumors during metastasis. It is known that, to orient themselves, cells can detect mechanical signals, such as the stiffness of their environment, and also that certain cells migrate from softer to stiffer environments, in a process known as durotaxis.
We found that, as the group of cancer cells migrated to stiffer surfaces, the cells first accelerated, but then slowed down, concluding that there is optimal rigidity at which cells migrate faster. We also observed that the cell groups adopted different shapes depending on the rigidity of the surface.
Most theories to understand this behavior do not take into account the three-dimensional shape of the group of cells. To address this limitation, we developed a new 3D model. Given the similarities i
n shape and behavior between cell groups and living droplets, we developed a theory of cell clusters as living droplets that can propagate and move over surfaces. Using the physics of surface tension, which is the force that makes water droplets spherical, we were able to explain the shapes and movement of groups of cells.
This finding shows that the physics of wetting, when generalized to living liquids, provides a way to understand cell migration without needing to consider the complexities of cell-cell communication.
The results of this study have the potential to lead to new treatments and therapies for cancer patients, by providing a better understanding of how cancer cells migrate and spread.
