Multilineage communication regulates human liver bud self-organization from pluripotency I

Conventional 2-D differentiation from pluripotency fails to recapitulate cell interactions occurring during organogenesis. 3-D organoids generate complex organ-like tissues, however it is unclear how heterotypic interactions impact lineage identity. Here we use single-cell RNA-seq to reconstruct hepatocyte-like lineage progression from pluripotency in 2-D culture. We then derive 3-D liver bud (LB) organoids by reconstituting hepatic, stromal, and endothelial interactions, and deconstruct heterogeneity during LB self-organization. We find that LB hepatoblasts differentiate towards hepatocyte fate, and in addition express epithelial migration signatures characteristic of organ budding. We identify hypoxia and inflammation signatures in endothelial and mesenchymal cells, which we suggest induce LB vasculogenesis. We use network analysis to predict autocrine and paracrine signaling in LBs, and show that VEGF crosstalk potentiates endothelial network formation and hepatoblast differentiation. Our molecular dissection reveals inter-lineage communication that is required for self-organization, and illuminates previously inaccessible aspects of human organ development and regeneration.