Soluble HLA-G in IVF/ICSI embryo culture supernatants does not always predict implantation success: a multicentre study.

Several reports have described an association between the presence of soluble human leukocyte antigen G (sHLA-G) in human embryo culture supernatants (ES) and implantation success. However, not all studies agree with these findings. To further document this debate, a multicentre blinded study was performed to investigate, on a large number of IVF ES and ICSI ES, whether sHLA-G is a useful criterion for embryo selection before transfer. A total of 1405 ES from 355 patients were collected from three assisted reproductive technique (ART) centres and evaluated for their sHLA-G content in a single laboratory, using a chemiluminescence enzyme-linked immunosorbent assay. In only one centre was a significant association between sHLA-G-positive ES and successful implantation established (P = 0.0379), whereas no such association was observed in the other centres. It was found that the percentages and concentrations of sHLA-G-positive ES varied between centres, depending on culture media and ART conditions. The percentage of sHLA-G-positive ES was significantly higher in IVF ES than ICSI ES (P < 0.001 and P < 0.01 for two centres). These data demonstrate that substantial variations of sHLA-G content in ES occur between different ART centres, highlighting the influence of several technical parameters that differ from one centre to another.

Follicular growth and oocyte competence in the in vitro cultured mouse follicle: effects of gonadotrophins and steroids.

Although there have been extensive studies on the effects of gonadotrophins and steroids on follicular development, less is known as to the effects these hormones have on the acquisition of oocyte developmental competence. This study investigates the effect of altering the gonadotrophin or steroidal environment on follicular development and on oocyte viability and DNA methylation. Oocytes were obtained from pre-ovulatory follicles after individual follicle culture from the pre-antral stage; gonadotrophin or steroid levels were manipulated during the culture period. Oocytes obtained from follicles grown in gonadotrophin free conditions were able to fertilize and develop to the blastocyst stage despite their impaired follicle development. There was no effect of luteinizing hormone or steroids on follicular growth. Altering the steroidal environment did, however, affect oocyte development. The oocytes of follicles exposed to high estrogen levels had lower fertilization rates, regardless of the presence or absence of high androgen levels. The combined presence of high levels of both steroids altered the level of global methylation. This study demonstrates that gonadotrophins and steroids influence the acquisition of developmental competence of the oocyte and suggests that optimal steroid exposure during follicle development is required for the oocyte to mature correctly.

sHLA-G production by human IVF embryos: can it be measured reliably?

A number of reports have demonstrated that sHLA-G can be detected in the culture medium of human IVF embryos and that levels correlate with the potential of an embryo to implant. This has aroused considerable interest in the IVF field. If sHLA-G can be used as a non-invasive marker of embryo quality, it will facilitate selection of the best embryos to transfer to the mother and thereby increase IVF pregnancy rates. However, there have been concerns about some aspects of these studies, including the sensitivity of the sHLA-G ELISAs used, the IVF culture conditions and the levels of sHLA-G which have been reported. A recent study by Sageshima et al. [J. Reprod. Immunol. 75, 11-22, 2007] attempts to address some of these concerns. However, despite using a sensitive ELISA, they were unable to detect sHLA-G in 111 embryo culture supernatants, or sHLA-G secretion by less than 10,000 sHLA-G transfected cells. They concluded that it is not possible to measure sHLA-G production by human embryos. This study has highlighted technical differences between IVF culture techniques and sHLA-G ELISAs that are currently confounding the system. Further collaboration between the research groups involved is required to establish robust reproducible systems that function identically in all laboratories.