Proteomic analysis of proprietary single-step preimplantation embryo culture media widely used in the United Kingdom.

OBJECTIVE

To study commercially available proprietary media used for human embryo culture to determine protein composition in a real-world clinic setting in United Kingdom.

DESIGN

Clinical and university-based laboratory study.

SUBJECTS: Unconditioned embryo culture media were assessed and did not involve any patients.

EXPOSURE: Unconditioned embryo culture media from four manufacturers were collected. All media were presupplemented with manufacturer protein source (typically human serum albumin or serum substitute supplement) to avoid any contamination. Different batches of 1-Step media (Sage) were also examined; these were collected directly from the bottle (Baseline) and kept in the Embryoscope culture system as a "sham culture" undisturbed. Sensitive data-independent acquisition liquid chromatography-mass spectrometry was used in this study to record protein composition in four brands of proprietary embryo culture media using international guidelines for protein identification from Human Proteome Organisation standards.

MAIN OUTCOME MEASURES: The number, identity, and relative abundance of proteins detected in proprietary embryo culture media across brands and sham-culture conditions using data-independent acquisition liquid chromatography-mass spectrometry.

RESULTS

The composition of proteins and their abundance were also studied after sham culture in conditions closely resembling those during clinical embryo culture. Across the media brands, we identified many additional proteins alongside human albumin. The proteomic dataset was annotated to proteins with known biological functions, including transcription regulators and cytoskeletal proteins. In a separate sham culture of an exemplar embryo culture medium (Sage 1-Step), proteomic analysis revealed the persistence of highly abundant proteins alongside albumin across multiple batches, including samples analyzed directly from the bottle and after several days in culture. Sham-culture experiments revealed persistence of detectable abundant proteins in unconditioned media.

CONCLUSION

Proteomic analysis of commercially available unconditioned human embryo culture media identified numerous proteins alongside albumin, providing a reference atlas for interpretation of future omics-based biomarker studies. We detected proteins reliably but did not establish any biological activity in the embryo culture environment. The detected proteins may derive from the base medium, protein supplements, or manufacturing background material, and their functional relevance to embryo development remains to be determined. Greater transparency from manufacturers regarding media constituents is warranted.