Exosomes derived from hypoxic mesenchymal stem cells restore ovarian function by enhancing angiogenesis

hucMSC-exosomes can be engineered to strengthen their therapeutic potential, and the present study aimed to explore whether hypoxic preconditioning can enhance the angiogenic potential of hucMSC-exosomes in an experimental model of POF. Primary hucMSCs and ROMECs were isolated from fresh tissue samples and assessed through a series of experiments. Exosomes were isolated from hucMSCs under normoxic or hypoxic conditions (norm-Exos and hypo-Exos, respectively) and then characterized using classic experimental methods. Based on a series of angiogenesis-related assays, we found that hypo-Exos significantly promoted ROMEC proliferation, migration, and tube formation and increased angiogenesis-promoting molecules in vitro. Histology, immunohistochemistry, and immunofluorescence experiments in a rat model of POF demonstrated that hypoxia pretreatment strengthens the therapeutic angiogenic effect of hucMSC-exosomes in vivo. Subsequently, high-throughput miRNA sequencing, qRT‑PCR analysis, and western blotting were employed to identify the potential molecular mechanism. We found that hypo-Exos enhance endothelial function and angiogenesis via the transfer of miR-205-5p in vitro and in vivo. Finally, based on the results of bioinformatics analysis, dual luciferase reporter assays, and gain- and loss-of-function studies, we found evidence indicating that exosomal miR-205-5p enhances angiogenesis by targeting the PTEN/PI3K/AKT/mTOR signalling pathway. These results indicated for the first time that exosomes derived from hypoxia-conditioned hucMSCs strongly enhance angiogenesis via the transfer of miR-205-5p by targeting the PTEN/PI3K/AKT/mTOR signalling pathway. Our findings provide a theoretical basis and demonstrate the potential application of a novel cell-free approach with stem cell-derived products in the treatment of POF.