Human Fallopian Tube EVs Enhance IVF Embryo Development and Deliver YWHAZ to Combat Oxidative Stress

In vitro fertilization (IVF) success rates are often limited by the suboptimal developmental quality of embryos, largely due to the oxidative stress inherent in standard culture conditions. The natural maternal environment, particularly the oviduct, provides crucial support for early embryogenesis, maintaining redox balance through mechanisms that are not fully replicated in vitro. Extracellular vesicles (EVs) from the oviduct are known to play a regulatory role, yet their specific molecular cargo and precise functional impact on human embryo development have remained poorly characterized, representing a significant gap in optimizing IVF outcomes.

Researchers isolated human Fallopian tube-derived extracellular vesicles (oEVs) and assessed their internalization by human preimplantation embryos. They then cultured human embryos with or without oEVs, monitoring developmental quality. A label-free proteomics approach identified 6505 oEV proteins, with functional validation focusing on YWHAZ. To confirm YWHAZ's role, Ywhaz-deficient mouse embryos were generated and analyzed for oxidative and apoptotic stress. Finally, engineered YWHAZ-loaded EVs were created and tested for their ability to be internalized by intact embryos and reduce intracellular ROS and apoptosis.

Human Fallopian tube-derived oEVs were rapidly internalized by human preimplantation embryos, significantly improving developmental quality in vitro. This led to an increase in high-quality Day 3 embryo formation and enhanced blastocyst development. Proteomic analysis of oEVs revealed 6505 proteins, with strong enrichment in metabolic, antioxidant, and stress-response pathways. YWHAZ was identified as a key conserved protein, abundant in oEVs and present across multiple embryo-related datasets. > Ywhaz-deficient mouse embryos exhibited elevated oxidative and apoptotic stress, transcriptional signatures of impaired glutathione metabolism, and failed to survive to birth despite normal blastocyst morphology. Recombinant YWHAZ protein alone could not enter intact embryos, but engineered YWHAZ-loaded EVs were efficiently internalized. These engineered EVs significantly reduced intracellular ROS and apoptosis, restoring redox status towards in vivo levels without compromising implantation or fetal growth.