Application of CRISPR-Based Epigenome Editing Tools for Engineering Programmable Embryo Models.

Stem cell-based embryo models (SEMs) have the potential to transform our understanding of early human embryogenesis. A critical step in engineering SEMs is the generation of the major cell types that compose preimplantation embryos including two primary extraembryonic lineages: (i) trophoblast cells, which are crucial for implantation and the establishment of maternal-fetal exchange, and (ii) hypoblast cells, which contribute to yolk sac formation. In addition, both cell types provide key signaling cues necessary for embryonic development. CRISPR-based epigenome editors are programmable devices that allow for efficient and precise activation (CRISPRa) or repression (CRISPRi) of cell fate-determining factors by modulating endogenous regulatory elements. Here, we present a step-by-step method to implement CRISPRa for controlling cell fate in embryonic stem cells based on our work in generation of CRISPR-programmed mouse embryo models.