Regulation of amnion induction during the human formative pluripotency transition

Human pluripotent stem cell(hPSC) represents a powerful tool to model early lineage decisions due to their capacity to differentiate to all somatic lineages and primordial germ cells. hPSC exists in distinct phases—naïve, formative, and primed—each with differing developmental potential. Naïve hPSC resembles the pre-implantation epiblast, retain trophectoderm (TE) potential, but are resistant to somatic lineages induction. Primed hPSC is related to post-implantation epiblast and readily form germ layers but lack TE potential. The formative transition, corresponding to the peri-implantation phase, represents a critical stage in acquiring multi-lineage competence. Capacitation, initiated by MEK/ERK inhibition withdrawal, drives naïve hPSC into a formative like phase in vitro. Amnion is an extraembryonic membrane that supports the embryo by providing protection, nutrient exchange, and signalling cues. Unlike rodent models, in humans, the amnion segregates from the epiblast shortly after implantation; however, this process remains unclear due to limited access to peri-implantation embryos. In this thesis, I establish a naïve hPSC-based model to study amniotic ectoderm (AME) segregation and explore pluripotency transitions modulate AME competency. Single cell RNA-sequencing reveals AME specification and confirms that the in vitro derived AME cells closely resemble embryo AME rather than TE. Unexpectedly, TE potential persists during early capacitation but gradually extinguishes as cells transition toward the primed state. Short-term TGF-β inhibition is sufficient to induce formative like cells into AME, paralleling events likely occurring in embryo. TGF-β inhibition downregulates SMAD7, facilitating increased BMP signalling which drives AME induction—a mechanism distinct from AME differentiation from primed hPSCs. Notably, the core pluripotency factor NANOG is suppressed by TGF-β/Nodal inhibition in capacitating cells but remains stable in naïve cells, indicating stage-specific signalling responses. Overall, this work provides insight into how dynamic shifts in pluripotency states regulate AME competence and uncovers the stage and mechanism underlying AME formation during the transition through formative pluripotency.<p></p>

Author dc:creator

• Zhi Zhang (21042092)

• Stem cell
• Amnion
• TGF-β

Statement dc:rights

• All rights reserved
• Open Access after 2027-10-03

Identifier

10779/exe.31931436.v1

OAI identifier oai:identifier

oai:figshare.com:article/31931436