This year, San Antonio was the place to be when participating in the annual meeting of ASRM. Similar to previous years, professionals from all over the world gathered to present or listen to the latest scientific developments in the field of assisted reproduction. We have collected our thoughts and reflections of the scientific content of the meeting in this blog post.
Closed vitrification system just as effective as an open device
Pujo et al presented a poster (P-181) demonstrating that the closed vitrification device Rapid-i is as effective as an open device for vitrification of human oocytes. The oocytes from 83 egg donors were split between the two devices. The survival rate with Rapid-i was significantly higher at 97%. Clinical outcomes, including live birth rate, were comparable between the two devices. This study provides further indication that although the cooling rate with closed devices are slower, it is the warming rate that determines success.
Enhancing implantation and determining genetic normality
Interleukin-6 (IL-6) is a modulator of the immune response, which is required for embryo implantation. In mouse embryos Galal et al (O-5) tested the hypothesis that adding IL-6 to the culture medium would enhance subsequent implantation. The results showed that IL-6 increased implantation from 55 to 76%.
Being able to take the culture medium and determine the genetic normality of the embryo that was individually cultured in that drop could dramatically change the way the DNA sample used in PGT (Pre-implantation genetic testing) is sourced. Lane et al., presented (O-146) a study investigating the concordance of the PGT result from the medium and corresponding embryo biopsy. By taking a sample of 10µl G-2 PLUS culture drop on Day 4 the embryo ploidy concordance was >95%.
New method to potentially determine metabolic efficiency and mitochondrial function
Fluorescence lifetime imaging microscopy was used to detect mitochondrial dysfunction in mouse oocytes by Wang et al (O-125). Autofluoresence of NADH and FAD+ reflects the oxidative phosphorylation occurring in the mitochondria. Differences could be detected between oocytes collected from wild type mice and those with compromised mitochondrial metabolism. This suggests that such imaging techniques could offer a non-invasive method to determine metabolic efficiency and mitochondrial function.
Time-lapse continues to provide more knowledge about embryo development
More and more clinics are using time-lapse technology as a tool to investigate the effect of procedures, conditions or parental traits or to learn more about embryo development. This was exemplified at this year's ASRM in several presentations including Arvizu et al. who utilised the continuous monitoring of embryos to determine potential differences in embryo developmenatal pace for advanced paternal age. For such embryos the time to reach blastocyst stage was longer. As the usable blastocyst rate was not affected by paternal age it is possible that results like these can be used to classify embryos for specific patient groups.
As time-lapse technology is becoming increasingly common in clinical application, continuously more data beyond implantation becomes available for clinics or clinic chains to analyse. Basile et al. from the IVI group of clinics in Spain presented data comparing delivery rates between cycles incubated and evaluated with EmbryoScope to those treated by traditional methods (P-135). This data-analysis showed significantly higher delivery rates for cycles done in the time-lapse setting and particularly for those involving double embryo transfers, although there were no differences in delivery rates between the two systems for cycles that had reached an ongoing pregnancy. For neonatal rates this study also showed improvements with the implementation of time-lapse technology, significantly for embryos transferred at blastocyst stage. This supports the data published earlier this year by the same group demonstrating the safety of culture in the EmbryoScope by obstetric and neonatal measures (Insua, Cobo et al. 2017).
One of the important aspects of implementing a comprehensive time-lapse system clinically is the shown improvement of the clinical workflow. At this year's ASRM one example of such improvements was presented by Watanabe et al. from Kanagawa Ladies Clinic in Japan (P-134). By incubating all ICSI-inseminated oocytes (n=3187) in the EmbryoScope time-lapse system they were able to better determine the correct status of fertilisation of an embryo and avoid compromising work schedules.
Time-lapse in combination with genetic testing
Genetic testing continues to be one of the hottest topics at ASRM. Previously published studies have shown an uplift in outcome rates by combining PGT and time-lapse technologies in embryology. One example from this years conference was the indication that applying time-lapse evaluation to euploid embryos can help differentiating embryos leading to live-birth from those leading to spontaneous abortion and that dynamic development patterns of the latter group were closer to that of euploid embryos not leading to a pregnancy after transfer (Rydze et al. (P-609)).
Do conditions in the IVF laboratories explain variation in mosaicism between clinics?
Mosaicism and its possible causes were discussed numerous times during the conference. It has been reported that the prevalence of mosaicism varies widely clinic to clinic. Katz-Jaffe et al reported (O-214) that of the >16,000 blastocysts analysed across 6 US clinics, which use similar optimised laboratory procedures, the prevalence of mosaic embryos was <3% (with no significant difference between the clinics). This percentage closely resembles mosaic rates observed in natural or IVF derived pregnancies. This raises the question if conditions in the IVF and/or the genetic laboratories can explain variation in mosaicism between clinics. One method that appears to not affect the PGT result is laser assisted biopsy. Kelk et al (O-215) used single cells from a cell line to determine if the exposure time to the laser and number of exposures could induce aneuploidy. No induction of aneuploidy was observed. Further investigations are needed, but it appears that other laboratory conditions could lead to the varying prevalence of mosaic embryos.
Find more information on ASRM's website or download our Selection of Abstracts below.