Spatial heterogeneities shape the collective behavior of signaling amoeboid cells

In its natural habitat in the forest soil, the cellular slime mold Dictyostelium discoideum is exposed to obstacles. Starving Dictyostelium cells secrete cAMP, which is the key extracellular signaling molecule that promotes the aggregation process required for their long-term survival. Here, we investigated the influence of environmental inhomogeneities on the signaling and pattern formation of Dictyostelium cells. We present experimental data and numerical simulations on the pattern formation of signaling Dictyostelium cells in the presence of periodic arrays of millimeter-sized pillars. We observed concentric cAMP waves that initiated almost synchronously at the pillars and propagated outward. In response to these circular waves, the Dictyostelium cells streamed toward the pillars, forming aggregates arranged in patterns that reflected the periodicity of the lattice of pillars. Our results suggest that, in nature, the excitability threshold and synchronization level of the cells are two key parameters that control the nature of the interaction between cells and spatial heterogeneities in their environment.