O-061 Single cell atlas of small RNAs in the human preimplantation embryo reveals the miRNA dynamics of lineage segregation

Abstract Study question How does the small non-coding RNA (sncRNA) expression profile of human embryo change from day three (E3) to seven (E7) preimplantation development? Summary answer From E3 E7, micro-RNA becomes more dynamic, targeting genes important for lineage segregation. What is known already The drivers specification [SP1] in remain unknown. SncRNAs regulate gene most biological systems studied date, with critical roles cell development, differentiation, and disease. well-studied class sncRNA, micro-RNAs (miRNAs), are required development peri-implantation stage animal models, their regulates embryonic stem differentiation vitro. design, size, duration Eighty-seven E3-E5 embryos donated research CReATe Fertility Centre (Veritas IRB#16580) between 2002 2021 were thawed cultured E3-E7. A total 1279 cells profiled sncRNAs. Of these, 463 had gender 189 co-sequenced mRNA complement. Participants/materials, setting, methods Good-quality by morphology enzymatically mechanically dissociated into single subjected large sequencing, as outlined Petropoulos et al. 2016 Hagemann-Jensen 2018. Gene was analyzed ‘Seurat’ package. MiRNA pathway analysis performed Mienturnet. Main results role chance We identified complete complement RNAs present embryo, piRNAs being abundant miRNAs increasing diversity abundance E7. Uniform Manifold Approximation Projection (UMAP) revealed progression developmental lineage. Split-cell co-sequencing canonical transcriptional markers allowing classification profiles 16-cell, early blast, inner mass (ICM), mural TE, polar TE populations. Enriched E5 ICM included miR-302b-5p miR-302c-3p, which have functions programming. Conversely, enriched miR-519b-3p, miR-519c-3p, miR-516a-5p, all members imprinted primate-specific microRNA cluster (C19MC), placenta formation. Targeting miRNA-gene networks involving Hedgehog, Hippo, FoxO signalling pathways, developmentally significant. Limitations, reasons caution This study on a center – handling culture conditions may influence sncRNA expression. Furthermore, ability these implant unknown, therefore we likely some non-viable embryos. Wider implications findings epigenomic changes drive segregation poorly understood, there vast differences conventional model humans. report first providing resource further exploration development. Trial registration number not applicable