Study of the Metabolomics of Equine Preovulatory Follicular Fluid: A Way to Improve Current In Vitro Maturation Media.
Authors: Fernández-Hernández Pablo, Sánchez-Calabuig María Jesús, García-Marín Luis Jesús, Bragado María J, Gutiérrez-Adán Alfonso, Millet Óscar, Bruzzone Chiara, González-Fernández Lauro, Macías-García Beatriz
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Follicular fluid provides the natural developmental environment for oocytes destined for ovulation, yet current in vitro maturation (IVM) media used in equine embryo production poorly replicate this composition—a potential explanation for the disappointingly low 10% success rate from oocyte retrieval to live foal. Researchers used proton nuclear magnetic resonance spectroscopy to characterise 22 metabolites present in preovulatory follicular fluid collected from postmortem mares, then compared these against the chemical profiles of the two most widely used IVM media: TCM-199 and DMEM/F-12. Nine metabolites identified in natural follicular fluid—including carnitine (0.09 mM), creatine phosphate (0.36 mM), citrate (0.4 mM), and notably lactate at 27.3 mM—are currently absent from commercial maturation media, whilst several core constituents like glucose showed substantial concentration discrepancies between follicular fluid (4.3 mM), TCM-199 (5.55 mM) and DMEM/F-12 (17.5 mM). These findings provide a biochemical roadmap for reformulating equine IVM media to better support oocyte nuclear and cytoplasmic maturation, potentially improving embryo competence and pregnancy outcomes in assisted reproduction programmes. For practitioners involved in embryo collection and transfer, this work underscores the importance of emerging research into media optimisation and suggests that refinements based on natural follicular chemistry may offer significant gains in reproductive efficiency.
Read the full abstract on PubMed
Practical Takeaways
- •Current commercial equine IVM media may be suboptimal; refinement of media composition based on follicular fluid metabolite profiles could improve the ~10% success rate in embryo production and foaling
- •Supplementation of standard IVM media with identified missing metabolites (particularly lactate and energy-related compounds) warrants investigation to enhance oocyte developmental competence
- •Laboratories performing equine embryo production via IVF/ICSI should consider media reformulation trials incorporating the nine identified absent metabolites to improve clinical outcomes
Key Findings
- •Twenty-two metabolites were identified in equine preovulatory follicular fluid using 1H-NMR spectroscopy
- •Nine metabolites present in follicular fluid are absent from standard IVM media (TCM-199 and DMEM/F-12), including lactate (27.3 mM), glucose-1-phosphate (6.9 mM), and acetylcarnitine (0.37 mM)
- •Glucose concentration differs significantly between follicular fluid (4.3 mM) and commonly used IVM media (5.55 mM in TCM-199 and 17.5 mM in DMEM/F-12)
- •Current equine oocyte IVM media composition does not fully replicate the biochemical environment of preovulatory follicular fluid, suggesting optimization potential