Mouse neural tube organoids self-organize floorplate through BMP-mediated cluster competition

Organoids can undergo pattern formation by spontaneously forming spatially-localised signaling centers called organisers. Understanding how molecular pathways participate in this regulative process is a central challenge in biology. Here, we investigated self-organisation of a SHH-expressing floorplate in clonal neural tube organoids (NTOs). In NTOs, a pulse of retinoic acid (RA) applied at Day 2 triggers self-organisation of a FOXA2+ floorplate by Day 6. FOXA2 expression was initially spatially scattered before resolving into multiple clusters. These FOXA2+ clusters underwent competition and physical sorting, resulting in a stable “winning” floorplate. We identified BMP signalling as a key governor of long-range cluster competition.