Quercetin-Loaded Mesenchymal Stem Cell Derived Extracellular Vesicles Enhance Ovarian Function in a Cyclophosphamide Induced Ovarian Damage

Background To investigate whether intraovarian administration of quercetin-loaded extracellular vesicles derived from Wharton’s jelly mesenchymal stem cells (EVs-QUE) improves ovarian function in a cyclophosphamide (CTX)-induced premature ovarian insufficiency (POI) rat model. Methods Human Wharton’s jelly-derived mesenchymal stem cells (MSCs) were cultured, and extracellular vesicles (EVs) were isolated and characterized by flow cytometry and electron microscopy. Quercetin was loaded onto EVs using ultrasonic incubation to generate EVs-QUE. A rat model of CTX-induced POI was established, and the subjects received intraovarian injections of either EVs or EVs-QUE. Ovarian function was assessed through histological evaluation, immunofluorescence staining, and gene expression analysis. Results Treatment with EVs-QUE significantly improved ovarian morphology and folliculogenesis, reduced the number of atretic follicles, and decreased Casp3 expression. Proliferation markers (Ki67, Pcna) and antioxidant genes (Nrf2, Sod1) were upregulated. Additionally, steroidogenesis- and oocyte-related genes (Star, Gdf9, Bmp15) showed increased expression. Although systemic hormonal alterations were limited, local tissue analysis confirmed a regenerative effect in the EVs-QUE group. Conclusions Quercetin-loaded EVs derived from Wharton’s jelly MSCs enhanced ovarian recovery in a CTX-induced POI model through anti-apoptotic, pro-proliferative, and antioxidant pathways. These findings suggest that intraovarian administration of EVs-QUE may represent a promising strategy for fertility preservation and warrant further investigation in long-term and translational studies.