Large-scale production of human blastoids amenable to modeling blastocyst development and maternal-fetal cross talk

Recent advances in human blastoids have opened new avenues for modeling early human development and implantation. One limitation of our first protocol for human blastoid generation was relatively low efficiency. We now report an optimized protocol for the efficient generation of large quantities of high-fidelity human blastoids from naive pluripotent stem cells. This enabled proteomics analysis that identified phosphosite-specific signatures potentially involved in the derivation and/or maintenance of the signaling states in human blastoids. Additionally, we uncovered endometrial stromal effects in promoting trophoblast cell survival, proliferation, and syncytialization during co-culture with blastoids and blastocysts. Side-by-side single-cell RNA sequencing revealed similarities and differences in transcriptome profiles between pre-implantation blastoids and blastocysts, as well as post-implantation cultures, and uncovered a population resembling early migratory trophoblasts during co-culture with endometrial stromal cells. Our optimized protocol will facilitate broader use of human blastoids as an accessible, perturbable, scalable, and tractable model for human blastocysts.

Automated summary

Recent advances in human blastoids have provided a new approach for modeling early human development and implantation. An optimized protocol for efficient generation of high-fidelity human blastoids has been reported, allowing for proteomics analysis and identification of specific signatures involved in blastoid signaling states. Additionally, the effects of endometrial stromal cells on trophoblast cell survival, proliferation, and syncytialization have been uncovered. Single-cell RNA sequencing revealed similarities and differences between blastoids and blastocysts, as well as a population resembling early migratory trophoblasts during co-culture with endometrial stromal cells. This optimized protocol will facilitate broader use of human blastoids as a reliable model for human blastocysts.