Systematic evaluation of blastoid models of early human development

Recent generation of stem cell-derived blastoids that recapitulate the architecture and cellular constitution of the human blastocyst offers an experimental model for the elucidation of the biology of early human development. To evaluate the fidelity of the blastoids for modelling human blastocysts, we first established a reference map of cell identity and lineage differentiation of the human blastocysts through the integration and curation of single-cell transcriptome data of ex vivo blastocysts profiled at a range of developmental timepoints in culture. We next use this reference map to assess the coverage and the authenticity of cell lineages and the progression of lineage differentiation of various blastoid models generated with different cellular sources and protocols. This reference map generated from this study enables the benchmarking of blastoids that may guide the optimization of the protocol for the generation of high-fidelity blastoid models that faithfully recapitulate the natural human blastocyst.