Embryonic Stem Cell-Derived Extracellular Vesicles Maintain ESC Stemness by Activating FAK.

It is critical that epiblast cells within blastocyst-stage embryos receive the necessary regulatory cues to remain pluripotent until the appropriate time when they are stimulated to undergo differentiation, ultimately to give rise to an entire organism. Here, we show that exposure of embryonic stem cells (ESCs), which are the in vitro equivalents of epiblasts, to ESC-derived extracellular vesicles (EVs) helps to maintain their stem cell properties even under culture conditions that would otherwise induce differentiation. EV-treated ESCs continued to express stemness genes, preserving their pluripotency and ability to generate chimeric mice. These effects were triggered by fibronectin bound to the surfaces of EVs, enabling them to interact with ESC-associated integrins and activate FAK more effectively than fibronectin alone. Overall, these findings highlight a potential regulatory mechanism whereby epiblast cells, via their shed EVs, create an environment within the blastocyst that prevents their premature differentiation and maintains their pluripotent state.