Generation of Blastocyst-like Structures from Mouse Embryonic and Adult Cell Cultures

Abstract

Highlights d A method that enables the generation of blastocyst-like structures from EPS cells d EPS-blastoids resemble blastocysts in morphology and celllineage allocation d EPS-blastoid formation recapitulates early developmental events in vitro d EPS-blastoids are able to implant in utero

Defining totipotency using criteria of increasing stringency

“…The ultimate proof of totipotency is the ability of a single cell type, or more stringently a single cell, to give rise to an entire blastocyst and subsequently a viable and fertile animal. Recently, blastocyst-like structures, termed blastoids, have been generated in vitro from different stem cell types 43,44,35,36 . These protocols use different combinations of growth factors and inhibitors to generate blastoids, which in multiple aspects resemble real blastocyst stage embryos, although until now none have been able to generate viable animals.…”

“…These protocols use different combinations of growth factors and inhibitors to generate blastoids, which in multiple aspects resemble real blastocyst stage embryos, although until now none have been able to generate viable animals. Most notably, two recent reports used D-EPSCs, either as a sole stem cell source (Belmonte group, B-blastoid) 35 or in combination with TSCs (Zernicka-Goetz group, ZG-blastoid) 36 to generate blastoids. Importantly, a large proportion of the blastoid cells generated with only D-EPSCs showed expression of genes previously associated with post-implantation stage lineages and not cells of the blastocyst.…”

“…Both cell types showed molecular and functional features that suggested expanded pluripotency, such as totipotency-associated marker gene expression and contribution to the EPI, PE as well as TE lineages using chimeric assays. Additionally, recent studies reported the ability of EPSCs, alone or in combination with TSCs, to self-assemble into blastocyst-like structures, termed blastoids, that contain cells with features of all three embryonic lineages 35,36 . These studies suggested that stem cells with the potential to give rise to both ICM and TE lineages, properties that define totipotent stem cells, can be isolated and expanded in vitro.…”

“…Notably, the B-blastoid method employs Bmp4 and inhibits Activin/Nodal signaling 35 , conditions which were also used in another blastoid protocol by the Tomoda lab 44 . The Tomoda group used EpiSCs as starting cells and were also able to produce blastoids with certain TE-like marker expression in the surface layer.…”

A New Microengineered Platform for 4D Tracking of Single Cells in a Stem‐Cell‐Based In Vitro Morphogenesis Model

“…[ 31 ] We believe that the application of such microthermoforming‐based technologies will aid future stem‐cell‐based morphogenesis models. Unleashing the full potential of P19‐based elongation model, gastruloids and other newly developed morphogenetic models of embryonic development [ 26,27,70,71 ] will require the development of more sophisticated microengineered platforms specifically designed to address the unanswered questions, a convergence that will make “morphogenetic micro engineering” [ 8 ] a reality in the near future.…”