Dual-patterned pluripotent stem cells self-organize into a human embryo model with extended anterior-posterior patterning

Human gastruloids are a powerful class of stem cell-derived models that recapitulate key features of early embryonic development, including symmetry breaking and the emergence of three germ layers. However, they lack anterior embryonic structures and coordinated axial organization. To address this limitation, we pre-patterned human pluripotent stem cells (hPSCs) by exposing them to either anterior (FGF2) or posterior (CHIR99021 [CHIR] & retinoic acid [RA]) cues. Upon mixing, these dual-patterned hPSCs interacted and self-organized into elongated structures with both anterior and posterior features—which we term anterior-posterior (AP) human gastruloids. Anteriorly pre-treated cells robustly intercalated into posteriorly pre-treated cells, collectively giving rise to a continuum of neural tissues—including a brain-like domain, a neural tube-like structure, and neuro-mesodermal progenitors (NMPs)—with segmented somites arrayed bilaterally. Single cell RNA sequencing (scRNA-seq) revealed that human AP gastruloids contain cell types resembling the midbrain-hindbrain boundary (MHB), regionalized hindbrain structures (i.e. rhombomeres 1–8), regionalized neural crest (i.e. cranial, vagal, trunk) and head mesoderm. Transcriptomic comparisons to primate embryos revealed that human AP gastruloids most closely resemble Carnegie stage 11 (CS11) embryos. While they lack a notochord and full dorsal-ventral polarity, human AP gastruloids recapitulate key spatial and temporal features of early neurulation and somitogenesis. Perturbation of folic acid metabolism or rho-associated kinase (ROCK) signaling induced spinal cord defects, phenocopying aspects of spina bifida and other neural tube defects, highlighting this model's potential for studying congenital disorders. AP gastruloids may serve as a simple, robust, scalable platform for modeling coordinated human AP body axis development. More broadly, our results suggest that controlled interactions between differentially prepatterned progenitors can initiate self-organization of complex body axis features. The “pattern-and-mix” strategy may serve as a generalizable framework for assembling spatially organized stem cell models of mammalian development. Overall design: In this study, we generated anterior-posterior (AP) human gastruloids from pre-patterned human pluripotent stem cells (hPSCs). Briefly, hPSCs were treated with either anterior cues (FGF2) or posterior cues (CHIR99021 and retinoic acid). After pre-patterning, the two populations were mixed, enabling them to interact and self-organize into elongated structures with coordinated anterior-posterior features. At 120 hours, AP gastruloids were collected and pooled for single-cell profiling using 10X Genomics technology.