Collective chemotaxis in a vertex model for confluent clusters

Many cell types exhibit chemotaxis, where they sense and climb biochemical signaling gradients in their microenvironments. Other cell types, like neural crest cells in lymphocytes and border cells in drosophila melanogaster, cannot climb gradients individually, but are able to chemotax in small clusters. Previous attempts at modeling collective chemotaxis have focused on particle-based models for cells, which may miss important interactions between cells in a confluent cluster, where there are no gaps or overlaps between cells. Therefore, we construct a 2D Voronoi model for a confluent tissue that incorporates feedback between individual cell properties and a biochemical signaling gradient. In our model, cells can sense the local concentration and adapt their individual surface tensions in response. This simple coupling of signaling and cell properties allows a cluster of cells to climb a gradient, while an individual cell is unable to do so.