Embryonic stem cell-derived extracellular vesicles alleviate ovarian dysfunction.

<h4>Background</h4>Premature ovarian insufficiency (POI) causes irreversible follicular depletion and infertility, and current treatments do not reliably preserve fertility after gonadotoxic chemotherapy. Recent work suggests extracellular vesicles from embryonic stem cells (ESC-EVs) can promote tissue regeneration, but it is unknown whether ESC-EVs can prevent or reverse POI, and which cellular programs they engage to restore ovarian function.<h4>Methods</h4>Here we tested ESC-EVs in a cyclophosphamide (Cy)-induced POI mouse model. We evaluated ovarian function by monitoring estrous cyclicity, follicle quantification, fertility, histology, fibrosis, and cellular senescence(definition). We isolated granulosa cells for transcriptomic profiling to define ESC-EV-driven molecular changes.<h4>Results</h4>ESC-EV treatment restored estrous cyclicity and improved fertility in Cy-induced mice, recovered follicle numbers, reduced stromal fibrosis and senescence marker expression, and activated estrogen‑responsive and gametogenesis gene programs. Granulosa cell transcriptomes showed reversal of Cy‑induced dysregulation of POI‑related genes (Figla, Nobox, Gdf9, Bmp15, Bcl2, Nfe2l2) and modulation of Nrf2 and DNA damage-response pathways.<h4>Conclusions</h4>ESC‑EVs rejuvenate the granulosa-oocyte niche by attenuating fibrosis and senescence and reactivating folliculogenic and estrogen‑responsive programs, thereby restoring ovarian function in a chemotherapy‑induced POI model. These results identify ESC‑EVs as a promising cell‑free regenerative approach for fertility preservation and ovarian rejuvenation.