Ricard Alert

Biological tissues spread like active liquids

 

When biological tissues such as your skin spread to heal a wound, the wound edge often becomes very undulated, forming finger-shaped cell streams. In our paper, we show that these ‘tissue fingers’ result from the fact that tissues spread like active liquids. Specifically, the tissue behaves like a liquid layer that is being pulled by the cells at the tissue edge, which actively crawl towards the wound. As a result of these pulling forces, the edge accelerates as the tissue spreads. As a consequence, more advanced regions of the tissue edge move faster than trailing regions, which gives rise to the finger-shaped streams. Thus, our findings show that the formation of tissue fingers needs not rely on a complex biological regulation of cell behavior. Rather, it may have a simple physical explanation; tissue fingers can emerge as an unavoidable consequence of making a fluid layer spread by pulling from its edge.