Metabolic Signature of Energy Metabolism Alterations and Excess Nitric Oxide Production in Culture Media Correlate with Low Human Embryo Quality and Unsuccessful Pregnancy

Metabolomic Biomarkers in Bovine Embryo Culture Media and Their Relationship with the Developmental Potential of In Vitro-Produced Embryos

Recent studies have shown that the metabolome of single embryo culture media is linked to successful pregnancy. In this study, the analysis was expanded to compare the metabolomes of viable and non-viable early-stage embryos and to examine metabolomic markers associated with hatching in viable embryos. The authors hypothesized that the metabolomic profiles of high-quality early blastocysts differ from those of non-viable embryos that reach the blastocyst stage but undergo developmental arrest at later stages. The metabolic profile of 43 spent bovine embryo culture medium samples were analyzed using liquid chromatography-mass spectrometry, covering 189 metabolites, including 40 acylcarnitines, 42 amino acids/biogenic amines, 91 phospholipids, 15 sphingolipids, and the sum of hexoses. Embryos were produced from abattoir-derived oocytes, and the culture medium samples were derived from Grade 1 early blastocysts that progressed to hatching (VBL; n = 10), non-viable early blastocysts that developed to the blastocyst stage but failed to hatch (DBL; n = 12), Grade 1 hatched blastocysts (HBL; n = 16), and plain growth media for control (CM; n = 5). It was observed that methionine sulfoxide (Met-SO) and lysophosphatidylcholine (lysoPC) C24:0 concentrations were significantly lower in the culture media from viable blastocysts compared to those from non-viable blastocysts (p < 0.001). Additionally, blastocysts that resulted in successful hatching had significantly lower levels of phospholipid, arginine (Arg), and methionine-related metabolites that significantly differentiated the control and viable blastocyst culture media from the media containing non-viable embryos. Building on previous studies, there appears to be an overlap in metabolites released during hatching that are also associated with successful pregnancy. The identified biomarkers can aid in assessing an embryo's developmental potential and enhance embryo selection for transfer or cryopreservation.

Associations of the Single Bovine Embryo Growth Media Metabolome with Successful Pregnancy

This study investigated whether metabolomic fingerprints of bovine embryo growth media improve the prediction of successful embryo implantation. In this prospective cohort study, the metabolome from in vitro-produced day 7 blastocysts with successful implantation (n = 11), blastocysts with failed implantation (n = 10), and plain culture media without embryos (n = 5) were included. Samples were analyzed using an AbsoluteIDQ® p180 Targeted Metabolomics Kit with LC-MS/MS, and a total of 189 metabolites were analyzed from each sample. Blastocysts that resulted in successful embryo implantation had significantly higher levels of methionine sulfoxide (p < 0.001), DOPA (p < 0.05), spermidine (p < 0.001), acetylcarnitine-to-free-carnitine ratio (p < 0.05), C2 + C3-to-free-carnitine ratio (p < 0.05), and lower levels of threonine (nep < 0.001) and phosphatidylcholine PC ae C30:0 (p < 0.001) compared to control media. However, when compared to embryos that failed to implant, only DOPA, spermidine, C2/C0, (C2 + C3)/C0, and PC ae C30:0 levels differentiated significantly. In summary, our study identifies a panel of differential metabolites in the culture media of bovine blastocysts that could act as potential biomarkers for the selection of viable blastocysts before embryo transfer.