Original title: Active wetting transition in cell aggregates
MJ Franco-Oñate, Hanno I. Hennighausen, Ricard Alert · August 2026
In the body, groups of cells often spread across surfaces like liquid droplets. Yet older models failed to explain partial wettingHow a liquid spreads on a surface, ranging from beading up to flattening into a thin film., where a tissue stops spreading and stays at an angle instead of flattening completely. To solve this, researchers modeled cell clusters as active liquid droplets that generate their own forces. In this model, tissue surface tension pulls the droplet together, while active pulling forces drag it outward across the surface. The authors found a sharp transition between partial and complete wetting, with conditions where both outcomes can happen. Unlike regular liquids, this shift depends on cell viscosity and surface friction. Adding internal contracting forces pulls the tissue in further, causing higher contact angles or complete detachment.
You are spreading frosting across a cake, trying to make an even layer. Usually how flat it spreads depends on how runny it is, and you can predict that from the recipe. Imagine the frosting instead pulls on the knife and the cake by itself, so the same frosting can end up flat, stay in a thick mound, or roll back together depending on how it is handled. In this paper, a clump of living cells is the frosting: the cells pull on the surface they sit on, and that self-generated pulling competes with the clump's own stickiness to decide whether it flattens, stops, or pulls back.
Knowing when a clump of living cells will spread out or stay put matters for biology, because tissues move this way in many natural processes. This work predicts the switch can be abrupt, and that under some conditions the same tissue could either spread completely or stop partway. It also explains why some tissues may pull together and detach entirely.
The abstract reports a theoretical prediction, not experiments. It does not test the model against measured contact angles or show which real tissues actually cross the transition. It also does not prove that the bistable region exists in actual aggregates, only that the model allows it.
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Active wetting transition in cell aggregates — MJ Franco-Oñate, Hanno I. Hennighausen, Ricard Alert
Abstract licence: CC0
Explanation generated by Synthesis from the abstract — it is not the original paper. This is a preprint, so it hasn't necessarily been peer reviewed.