Unconditioned commercial embryo culture media contain a large variety of non-declared proteins: a comprehensive proteomics analysis.
BACKGROUND New approaches for non-invasive embryo-quality assessment are among the major goals in Reproductive Medicine. We hypothesize that the detection of changes in the protein profile of the culture media in which blastocysts are cultured could be a potential indicator of the viability of the embryo and, thus, a useful tool for selecting the more appropriate blastocysts to be transferred. METHODS Using protein-array technology, we analysed the protein profile corresponding to 24 h conditioned media of blastocysts that implanted versus those that did not implant. A statistical approach was followed to compare each of these media versus a medium in the absence of blastocysts (control medium). In addition, a gene ontology functional analysis-including those proteins showing a statistical difference among conditions-was performed, and a network with the predicted functional partners and corresponding relationships was obtained. RESULTS The soluble TNF receptor 1 and IL-10 increased significantly and MSP-alpha, SCF, CXCL13, TRAILR3 and MIP-1beta decreased significantly when the protein profile of the blastocyst culture medium was compared with the control medium. CXCL13 (BLC) and granulocyte-macrophage colony-stimulating factor was also decreased significantly in the implanted blastocyst media compared with that in media from the non-implanted counterparts with a similar morphology. None of the proteins included in the array was increased significantly in the implanted blastocyst-conditioned media. CONCLUSIONS The differences identified in the protein profile of the culture media in the presence of implanted versus non-implanted blastocysts can be considered a new non-invasive approach in the search for new tools to diagnose blastocyst viability.