Embryonic soluble HLA-G as a marker of developmental potential in embryos

BACKGROUND: In human reproduction, embryo implantation is complex and poorly understood. At present, no single markers are used in routine treatment to assay biochemical functions of the human embryo. Soluble human leukocyte antigen-G (sHLA-G) could be considered a possible marker of embryo developmental potential. It is localized primarily on the extravillous trophoblast, making this antigen a potential mediator of immune interaction at the maternal-fetal interface during gestation. METHODS: Soluble-HLA-G levels were evaluated by an enzyme-linked immunosorbent assay (ELISA) employing monoclonal antibody MEM-G9. It was evaluated in 318 media of single embryo cultures. We correlated the presence of sHLA-G with embryo morphology and the pregnancy obtained in that treatment cycle. RESULTS: No correlation was found between embryo morphology and sHLA-G levels. Pregnancy was observed only when the medium of at least one transferred embryo contained sHLA-G. In 26 out of 66 patients, none of the obtained embryos showed any detectable sHLA-G molecules and no pregnancy occurred. CONCLUSIONS: From our results, we propose sHLA-G as a potential marker of embryo development: the sHLA-G ELISA can be a useful biochemical assay in addition to embryo morphology in embryo selection for transfer in IVF treatment if there are other embryos with the same morphology.