Zona-pellucida-inspired cellular microenvironment induces the formation of human blastoids from primed human pluripotent stem cells

Human blastoids provide an in vitro, embryo-free model for human implantation; however, current protocols depend on genetically unstable naïve human pluripotent stem cells (hPSCs). Here, instead of using naïve hPSCs, we report a hydrogel-based strategy that directly generates human blastoids from standard primed hPSCs. A 10% w/v poly(N-isopropyl-acrylamide)–PEG matrix mimics the zona pellucida by providing negligible adhesion and gentle confinement. Within nine days, aggregates cavitate and form epiblast, primitive endoderm, and trophectoderm—including a CCR7⁺ polar subset—attach to the extracellular matrix, secrete hCG, and initiate extravillous differentiation. Single-cell RNA-seq and RNA velocity analyses reveal early pruning of paracrine networks, preservation of an FGF2 core, and later lineage-specific reconnection. Comparative interactomics place hydrogel blastoids closest to day-5–7 embryos and show marked suppression of VEGF, PDGF, and CXCL inflammatory cues typical of naïve-cell models. This minimal, feeder-free niche enables scalable production of blastoids containing EPI, PrE, and TE-like cells from primed hPSCs.