Characterization and miRNA profiling of extracellular vesicles from rabbit oviduct and uterine fluids

The oviduct and uterus provide a supportive environment for early embryonic development, where effective embryo-maternal communication is essential for pregnancy success. Extracellular vesicles (EVs) from oviductal (OF) and uterine fluids (UF) are key mediators of this communication, transporting bioactive molecules such as proteins, lipids, DNA, and regulatory RNAs. Among these, microRNAs (miRNAs) are particularly interesting due to their role in modulating reproductive processes. Although underrepresented in EVs research, the rabbit offers a robust model owing to its inducible ovulation, controlled reproductive physiology, and similarities to human implantation dynamics. This study aims to uncover, in does, how EVs could influence key reproductive processes by isolating, characterizing, and analyzing the miRNA cargo from OF- and UF-EVs. We identified 388 miRNAs in both OF-EVs and UF-EVs, 18 miRNAs were significantly more abundant in UF-EVs, while 5 were less abundant compared to OF-EVs group, suggesting distinct roles in embryo-maternal communication. The most abundant miRNAs, included ocu-miR-148a-3p, ocu-let-7i-5p, and ocu-miR-10b-5p, related to embryo development and implantation. Target gene prediction analysis revealed that OF-EVs miRNAs are linked to MAPK, Hippo, TGF-β, Ras, PI3K-Akt, and mTOR pathways, while UF-EVs are associated with Hippo, PI3K-Akt, FoxO, endocytosis, and mTOR pathways, essential for cell proliferation, differentiation, immune regulation, and embryo-maternal interactions. Our findings suggest that EVs in rabbit reproductive fluids could play a fundamental role in early embryonic development. Future research should focus on the functional validation of these key candidate miRNAs, particularly those involved in reproductive physiology, offering promising insights for reproductive biotechnology and veterinary medicine.