GC-MS/MS analysis of metabolites derived from a single human blastocyst

Steady morphokinetic progression is an independent predictor of live birth: a descriptive reference for euploid embryos

STUDY QUESTION

Can modelling the longitudinal morphokinetic pattern of euploid embryos during time-lapse monitoring (TLM) be helpful for selecting embryos with the highest live birth potential?

SUMMARY ANSWER

Longitudinal reference ranges of morphokinetic development of euploid embryos have been identified, and embryos with steadier progression during TLM are associated with higher chances of live birth.

WHAT IS KNOWN ALREADY

TLM imaging is increasingly adopted by fertility clinics as an attempt to improve the ability of selecting embryos with the highest potential for implantation. Many markers of embryonic morphokinetics have been incorporated into decision algorithms for embryo (de)selection. However, longitudinal changes during this temporal process, and the impact of such changes on embryonic competence remain unknown. Aiming to model the reference ranges of morphokinetic development of euploid embryos and using it as a single longitudinal trajectory might provide an additive value to the blastocyst morphological grade in identifying highly competent embryos.

STUDY DESIGN SIZE DURATION

This observational, retrospective cohort study was performed in a single IVF clinic between October 2017 and June 2021 and included only autologous single euploid frozen embryo transfers (seFET).

PARTICIPANTS/MATERIALS SETTING METHODS

Reference ranges were developed from [hours post-insemination (hpi)] of the standard morphokinetic parameters of euploid embryos assessed as tPB2, tPNa, tPNf, t2-t9, tSC, tM, tSB, and tB. Variance in morphokinetic patterns was measured and reported as morphokinetic variance score (MVS). Nuclear errors (micronucleation, binucleation, and multinucleation) were annotated when present in at least one blastomere at the two- or four-cell stages. The blastocyst grade of expansion, trophectoderm (TE), and inner cell mass (ICM) were assessed immediately before biopsy using Gardner's criteria. Pre-implantation genetic diagnosis for aneuploidy (PGT-A) was performed by next-generation sequencing. All euploid embryos were singly transferred in a frozen transferred cycle and outcomes were assessed as live birth, pregnancy loss, or not pregnant. Association of MVS with live birth was investigated with regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

TLM data from 340 seFET blastocysts were included in the study, of which 189 (55.6%) resulted in a live birth. The median time for euploid embryos to reach blastulation was 109.9 hpi (95% CI: 98.8-121.0 hpi). The MVS was calculated from the variance in time taken for the embryo to reach all morphokinetic points and reflects the total morphokinetic variability it exhibits during its development. Embryos with more erratic kinetics, i.e. higher morphokinetic variance, had higher rates of pregnancy loss (P = 0.004) and no pregnancy (P < 0.001) compared to embryos with steadier morphokinetic patterns. In the multivariable analysis adjusting for ICM, TE grade, presence of nuclear errors, and time of blastulation, MVS was independently associated with live birth (odds ratio [OR]: 0.62, 95% CI: 0.46-0.84, P = 0.002) along with ICM quality. Live birth rate of embryos with the same ICM grading but different morphokinetic variance patterns differed significantly. Live birth rates of embryos exhibiting low MVS with ICM grades A, B, and C were 85%, 76%, and 67%, respectively. However, ICM grades A, B, and C embryos with high MVS had live birth rates of 65%, 48%, and 21% (P < 0.001). The addition of the MVS to embryo morphology score (ICM and TE grading) significantly improved the model's AUC value (0.67 vs 0.62, P = 0.015) and this finding persisted through repeat cross-validation (0.64 ± 0.08 vs 0.60 ± 0.07, P < 0.001).

LIMITATIONS REASONS FOR CAUTION

The exclusion of IVF cases limits, for now, the utility of the model to only ICSI-derived embryos. The utility of these reference ranges and the association of MVS with various clinical outcomes should be further investigated.

WIDER IMPLICATIONS OF THE FINDINGS

We have developed reference ranges for morphokinetic development of euploid embryos and a marker for measuring total morphokinetic variability exhibited by developed blastocysts. Longitudinal assessment of embryonic morphokinetics rather than static time points may provide more insight about which embryos have higher live birth potential. The developed reference ranges and MVS show an association with live birth that is independent of known morphological factors and could emerge as a valuable tool in prioritizing embryos for transfer.

STUDY FUNDING/COMPETING INTERESTS

This study received no external funding. The authors declare no conflicting interests.

TRIAL REGISTRATION NUMBER

N/A.

Quantitative Proteomics and Metabolomics of Culture Medium from Single Human Embryo Reveal Embryo Quality-Related Multiomics Biomarkers

An effective tool to assess embryo quality in the assisted reproduction clinical practice will enhance successful implantation rates and mitigate high risks of multiple pregnancies. Potential biomarkers secreted into culture medium (CM) during embryo development enable rapid and noninvasive methods of assessing embryo quality. However, small volumes, low biomolecule concentrations, and impurity interference collectively preclude the identification of quality-related biomarkers in single blastocyst CM. Here, we developed a noninvasive trace multiomics approach to screen for potential markers in individual human blastocyst CM. We collected 84 CM samples and divided them into high-quality (HQ) and low-quality (LQ) groups. We evaluated the differentially expressed proteins (DEPs) and metabolites (DEMs) in HQ and LQ CM. A total of 504 proteins and 189 metabolites were detected in individual blastocyst CM. Moreover, 9 DEPs and 32 DEMs were identified in different quality embryo CM. We also categorized HQ embryos into positive implantation (PI) and negative implantation (NI) groups based on ultrasound findings on day 28. We identified 41 DEPs and 4 DEMs associated with clinical implantation outcomes in morphologically HQ embryos using a multiomics analysis approach. This study provides a noninvasive multiomics analysis technique and identifies potential biomarkers for clinical embryo developmental quality assessment.

The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature

One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.

Rapid and non-invasive diagnostic techniques for embryonic developmental potential: a metabolomic analysis based on Raman spectroscopy to identify the pregnancy outcomes of IVF-ET

The non-invasive and rapid assessment of the developmental potential of embryos is of great clinical importance in assisted reproductive technology (ART). In this retrospective study, we analyzed the metabolomics of 107 samples provided by volunteers and utilized Raman spectroscopy to detect the substance composition in the discarded culture medium of 53 embryos resulting in successful pregnancies and 54 embryos that did not result in pregnancy after implantation. The culture medium from D3 cleavage-stage embryos was collected after transplantation and a total of 535 (107 × 5) original Raman spectra were obtained. By combining several machine learning methods, we predicted the developmental potential of embryos, and the principal component analysis-convolutional neural network (PCA-CNN) model achieved an accuracy rate of 71.5%. Furthermore, the chemometric algorithm was used to analyze seven amino acid metabolites in the culture medium, and the data showed significant differences in tyrosine, tryptophan, and serine between the pregnancy and non-pregnancy groups. The results suggest that Raman spectroscopy, as a non-invasive and rapid molecular fingerprint detection technology, shows potential for clinical application in assisted reproduction.

Does conventional morphological evaluation still play a role in predicting blastocyst formation?

BACKGROUND

Advanced models including time-lapse imaging and artificial intelligence technologies have been used to predict blastocyst formation. However, the conventional morphological evaluation of embryos is still widely used. The purpose of the present study was to evaluate the predictive power of conventional morphological evaluation regarding blastocyst formation.

METHODS

Retrospective evaluation of data from 15,613 patients receiving blastocyst culture from January 2013 through December 2020 in our institution were reviewed. Generalized estimating equations (GEE) were used to establish the morphology-based model. To estimate whether including more features regarding patient characteristics and cycle parameters improve the predicting power, we also establish models including 27 more features with either LASSO regression or XGbosst. The predicted number of blastocyst were associated with the observed number of the blastocyst and were used to predict the blastocyst transfer cancellation either in fresh or frozen cycles.

RESULTS

Based on early cleavage and routine observed morphological parameters (cell number, fragmentation, and symmetry), the GEE model predicted blastocyst formation with an AUC of 0.779(95%CI: 0.77-0.787) and an accuracy of 74.7%(95%CI: 73.9%-75.5%) in the validation set. LASSO regression model and XGboost model based on the combination of cycle characteristics and embryo morphology yielded similar predicting power with AUCs of 0.78(95%CI: 0.771-0.789) and 0.754(95%CI: 0.745-0.763), respectively. For per-cycle blastocyst yield, the predicted number of blastocysts using morphological parameters alone strongly correlated with observed blastocyst number (r = 0.897, P < 0.0001) and predicted blastocyst transfer cancel with an AUC of 0.926((95%CI: 0.911-0.94).

CONCLUSION

The data suggested that routine morphology observation remained a feasible tool to support an informed decision regarding the day of transfer. However, models based on the combination of cycle characteristics and embryo morphology do not increase the predicting power significantly.

Why Has Metabolomics So Far Not Managed to Efficiently Contribute to the Improvement of Assisted Reproduction Outcomes? The Answer through a Review of the Best Available Current Evidence

Metabolomics emerged to give clinicians the necessary information on the competence, in terms of physiology and function, of gametes, embryos, and the endometrium towards a targeted infertility treatment, namely, assisted reproduction techniques (ART). Our minireview aims to investigate the current status of the use of metabolomics in assisted reproduction, the potential flaws in its use, and to propose specific solutions towards the improvement of ART outcomes through the use of the intervention. We used published reports assessing the role of metabolomic investigation of the endometrium, oocytes, and embryos in improving clinical outcomes in women undergoing ART. We initially found that there is no evidence to support that fertility outcomes can be improved through metabolomics profiling. In contrast, it may be helpful for understanding and appraising the nutritional environment of oocytes and embryos. The causes include the different infertility populations, the difference between animals and humans, technical limitations, and the great heterogeneity in the variables employed. Suggested steps include the standardization of variables of the method itself, the universal creation of a panel where all biomarkers are stored concerning specific infertile populations with different phenotypes or etiologies, specific bioinformatics contribution, significant computing power for data processing, and importantly, properly conducted trials.

Current Advancements in Noninvasive Profiling of the Embryo Culture Media Secretome

There have been over 8 million babies born through in vitro fertilization (IVF) and this number continues to grow. There is a global trend to perform elective single embryo transfers, avoiding risks associated with multiple pregnancies. It is therefore important to understand where current research of noninvasive testing for embryos stands, and what are the most promising techniques currently used. Furthermore, it is important to identify the potential to translate research and development into clinically applicable methods that ultimately improve live birth and reduce time to pregnancy. The current focus in the field of human reproductive medicine is to develop a more rapid, quantitative, and noninvasive test. Some of the most promising fields of research for noninvasive assays comprise cell-free DNA analysis, microscopy techniques coupled with artificial intelligence (AI) and omics analysis of the spent blastocyst media. High-throughput proteomics and metabolomics technologies are valuable tools for noninvasive embryo analysis. The biggest advantages of such technology are that it can differentiate between the embryos that appear morphologically identical and has the potential to identify the ploidy status noninvasively prior to transfer in a fresh cycle or before vitrification for a later frozen embryo transfer.