Systematic characterization of methods for inducing human naïve pluripotency [Registered Report Stage 1 Protocol]

ABSTRACT Since their derivation, human pluripotent stem cells (hPSCs) have been maintained in a “primed” pluripotent state in vitro, corresponding to embryonic cells of the post-implantation blastocyst. To mimic cells of the pre-implantation blastocyst, the field has devised protocols to revert primed hPSCs to an earlier embryonic, “naïve”, state that can be used to derive in vitro blastocyst-like structures, “blastoids”, providing an interesting model of human pre-implantation embryos. Despite their utility in understanding fundamental cell biology and early embryology, in vitro naïve hPSCs are prone to karyotypic abnormalities and the efficacy of their derivation varies across protocols and cell lines. To promote their reproducibility and reliability in the field, we here apply two widely adopted methods for naïve induction on several hPSC lines varying initial culture conditions while systematically assessing the quality of resulted cells by transcriptional profiling, karyotyping, and blastoid formation ability.</p

Regionalisation of the mouse visceral endoderm as the blastocyst transforms into the egg cylinder-1

<p><b>Copyright information:</b></p><p>Taken from "Regionalisation of the mouse visceral endoderm as the blastocyst transforms into the egg cylinder"</p><p>http://www.biomedcentral.com/1471-213X/7/96</p><p>BMC Developmental Biology 2007;7():96-96.</p><p>Published online 16 Aug 2007</p><p>PMCID:PMC1978209.</p><p></p>the ICM at the blastocyst stage. They are shown as a fluorescent projection of a confocal z series merged with a transmitted light section, at the early egg cylinder (EEC) stage (A, C, F), E5.5 (B, D, G) and E6.5 (E, H). For each stage, the number of labelled conceptuses considered (n) and the percentage of those with colonisation of the embryonic region only (Emb, A-B), the extra-embryonic region only (Xemb, C-E) or both (Xemb+Emb, F-H) is indicated. Arrowheads point to the embryonic/extra-embryonic junction. Conceptuses are oriented with the anterior pole on the left, whenever it can be identified. Scale bars 20 μm

Basal delamination during mouse gastrulation primes pluripotent cells for differentiation.

The blueprint of the mammalian body plan is laid out during gastrulation, when a trilaminar embryo is formed. This process entails a burst of proliferation, the ingression of embryonic epiblast cells at the primitive streak, and their priming toward primitive streak fates. How these different events are coordinated remains unknown. Here, we developed and characterized a 3D culture of self-renewing mouse embryonic cells that captures the main transcriptional and architectural features of the early gastrulating mouse epiblast. Using this system in combination with microfabrication and in vivo experiments, we found that proliferation-induced crowding triggers delamination of cells that express high levels of the apical polarity protein aPKC. Upon delamination, cells become more sensitive to Wnt signaling and upregulate the expression of primitive streak markers such as Brachyury. This mechanistic coupling between ingression and differentiation ensures that the right cell types become specified at the right place during embryonic development