Physics has a long tradition of learning about fundamental interactions by making particles collide against each other. Could a similar approach be applied to biological systems? Work by Ricard Alert of the Max Planck Institute for the Physics of Complex Systems and collaborators shows what can be learnt about the mechanics of living tissues by making them collide against each other. In experiments, the researchers placed cell monolayers on a substrate and allowed them to expand and collide. The work first characterised how two tissues change shape upon collision. The researchers discovered that denser tissues, with more cells per unit area, can mechanically displace less dense tissues. Based on their calculations, the team proposes that this displacement arises because denser tissues have a higher pressure, which allows them to push on other tissues. This theory enables measurements of the elastic properties of the tissues just from their displacements upon collision. The researchers then analyzed collisions between three tissues. Surprisingly, they found that these three-tissue events are not simply a superposition of two-tissue collisions. Instead, some cells speed up as if trying to squeeze between the two other tissues. Finally, they used all these collision principles to design and assemble specific tissue patterns, similar to tile patterns, like the diamond pattern in the image. Ultimately, these results might help engineering tissue composites for implants, as well as understanding and controlling tissue interactions during embryonic development or wound healing. In all these situations, tissues grow and collide, either merging into a single tissue or establishing clear boundaries between different tissues and organs.
Original Publication:
Heinrich, M.A., Alert, R., Wolf, A.E. et al. Self-assembly of tessellated tissue sheets by expansion and collision. Nat Commun 13, 4026 (2022). doi.org/10.1038/s41467-022-31459-1
Originally published by the Max Planck Institute for the Physics of Complex Systems on 2nd May 2023 – original article can be found here: https://www.pks.mpg.de/research/highlights