Non-invasive assessment of embryo viability by metabolomic profiling of culture media (‘metabolomics’)

Noninvasive amino acid turnover predicts human embryo aneuploidy

Assisted reproduction technology has two significant problems: low success rates and multiple pregnancies. Because of these problems, the priority in IVF clinics is to develop a potential diagnostic test that can be used to select the embryos with the ultimate developmental competence. Aneuploidy screening as embryo selection criteria will ensure that the transferred embryos are euploid and high implantation rate. We hypothesize that aneuploidy in human preimplantation embryos could be discriminated by their amino acid metabolism profile in the spent culture media. Preimplantation genetic testing for aneuploidy results and spent embryo culture medium amino acid content were analyzed for 58 couples. The next-generation sequencing technique was used and coupled with TE biopsy. Forty euploid and 71 aneuploid blastocysts were evaluated. Embryos were cultured individually until day 5 or 6 of embryo development. Spent culture medium was collected after finishing the culture. There was no statistical difference between D3 and D5 embryo morphology between euploid and aneuploid embryos (p > .05). Eight amino acids, including SER, GLY, HIS, ARG, THR, ALA, PRO, and TYR, were detected in the culture medium from the blank control group, euploid group, and aneuploid group. Only TYR amino acid concentration was found significantly higher in the aneuploid group compared to the euploid group (p < .003). Tyrosine amino acid levels equal to and above 76.38 µmol/L could be considered aneuploid. Aneuploid embryos demonstrate altered amino acid turnover in vitro relative to euploid counterparts. A noninvasive method of amino acid profiling will be of value as a tool for routine preimplantation embryo selection among all patient groups.

Necessity is the mother of invention and the evolutionary force driving the success of in vitro fertilization

During the last few decades, millions of healthy children have been born with the aid of in vitro fertilization (IVF). This success belies the fact that IVF treatment is comprised of a complex series of interventions starting with a customized control ovarian stimulation protocol. This is followed by the induction of oocyte maturation, the retrieval of mature oocytes and in vitro fertilization, which often involves the microinjection of a single sperm into the oocyte. After fertilization, the resulting embryos are cultured for up to 7 days. The best embryos are transferred into the uterus where the embryo implants and hopefully develops into a healthy child. However, frequently the best embryos are biopsied and frozen. The biopsied cells are analyzed to identify those embryos without chromosomal abnormalities. These embryos are eventually thawed and transferred with pregnancy rates as good if not better than embryos that are not biopsied and transferred in a fresh cycle. Thus, IVF treatment requires the coordinated efforts of physicians, nurses, molecular biologists and embryologists to conduct each of these multifaceted phases in a seamless and flawless manner. Even though complex, IVF treatment may seem routine today, but it was not always the case. In this review the evolution of human IVF is presented as a series of innovations that resolved a technical hurdle in one component of IVF while creating challenges that eventually lead to the next major advancement. This step-by-step evolution in the treatment of human infertility is recounted in this review.

Alpha-1 chain of human haptoglobin as viability marker of in vitro fertilized human embryos: information beyond morphology

Only one third of the in vitro fertilization treatments result in successful delivery following morphological viability assessment worldwide. A paper by Montskó et al. (2015) describes the identification of the alpha-1 chain of human haptoglobin as a potential marker of embryo viability. Using mass spectrometry, the concentration of the haptoglobin alpha-1 chain was determined in spent culture media samples of in vitro fertilized embryos and correlation was found with the outcome of the respective transfer. In the present study we investigated, whether the concentration of haptoglobin alpha-1 chain shows any correlation with morphological scores to clarify whether levels of the alpha-1 chain provide additional information on embryo viability unnoticed by the morphological assessment. In the study, pregnancy and live birth rates were examined in 143 transferred samples of 86 patients, retrospectively. Two sample groups were created. The control group contained embryos classified as 'good' or 'fair' based on the Istanbul Consensus Criteria System, while the double-assay group contained embryos assessed as 'good' or 'fair' by the morphological evaluation and as 'viable' by the haptoglobin assay. Clinical pregnancy rate was 30.2% in the control group, while 47.6% in the group scored parallel with morphological criteria and proteomic analysis (p < 0.05). The increased clinical pregnancy rate observed in the double-assayed group can be attributed to decreased false-positivity of the double assay. Abbreviations: IVF: in vitro fertilization; SEC: spent embryo culture medium; HSA: human serum albumin; Hpt: haptoglobin; HptA1: haptoglobin alpha-1 chain; ICCS: Istanbul Consensus Criteria System; BMI: body mass index; ICSI: intracytoplasmic sperm injection.

NGS Analysis of Human Embryo Culture Media Reveals miRNAs of Extra Embryonic Origin

Our objective in this work was to isolate, identify, and compare micro-RNAs (miRNAs) found in spent culture media of euploid and aneuploid in vitro fertilization (IVF) embryos. Seventy-two embryos from 62 patients were collected, and their spent media were retained. A total of 108 spent conditioned media samples were analyzed (n = 36 day 3 euploid embryos, n = 36 day 3 aneuploid embryos, and n = 36 matched control media). Fifty hed-control media embryos were analyzed using next-generation sequencing (NGS) technology. We detected 53 known human miRNAs present in the spent conditioned media of euploid and aneuploid IVF embryos. miR-181b-5p and miR-191-5p were found the most represented. We validated our results by quantitative polymerase chain reaction (qPCR), but no significant results were obtained between the groups. In conclusion, we obtained the list of miRNAs present in the spent conditioned media from euploid and aneuploid IVF embryos, but our data suggest that these miRNAs could have a nonembryonic origin.

Metabolomics for improving pregnancy outcomes in women undergoing assisted reproductive technologies

BACKGROUND

In order to overcome the low effectiveness of assisted reproductive technologies (ART) and the high incidence of multiple births, metabolomics is proposed as a non-invasive method to assess oocyte quality, embryo viability, and endometrial receptivity, and facilitate a targeted subfertility treatment.

OBJECTIVES

To evaluate the effectiveness and safety of metabolomic assessment of oocyte quality, embryo viability, and endometrial receptivity for improving live birth or ongoing pregnancy rates in women undergoing ART, compared to conventional methods of assessment.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Trials Register, CENTRAL, MEDLINE, Embase, CINAHL and two trial registers (Feburary 2018). We also examined the reference lists of primary studies and review articles, citation lists of relevant publications, and abstracts of major scientific meetings.

SELECTION CRITERIA

Randomised controlled trials (RCTs) on metabolomic assessment of oocyte quality, embryo viability, and endometrial receptivity in women undergoing ART.

DATA COLLECTION AND ANALYSIS

Pairs of review authors independently assessed trial eligibility and risk of bias, and extracted the data. The primary outcomes were rates of live birth or ongoing pregnancy (composite outcome) and miscarriage. Secondary outcomes were clinical pregnancy, multiple and ectopic pregnancy, cycle cancellation, and foetal abnormalities. We combined data to calculate odds ratios (ORs) for dichotomous data and 95% confidence intervals (CIs). Statistical heterogeneity was assessed using the I² statistic. We assessed the overall quality of the evidence for the main comparisons using GRADE methods.

MAIN RESULTS

We included four trials with a total of 924 women, with a mean age of 33 years. All assessed the role of metabolomic investigation of embryo viability. We found no RCTs that addressed the metabolomic assessment of oocyte quality or endometrial receptivity.We found low-quality evidence of little or no difference between metabolomic and non-metabolomic assessment of embryos for rates of live birth or ongoing pregnancy (OR 1.02, 95% CI 0.77 to 1.35, I² = 0%; four RCTs; N = 924), live birth alone (OR 0.99, 95% CI 0.69 to 1.44, I² = 0%; three RCTs; N = 597), or miscarriage (OR 1.18, 95% CI 0.77 to 1.82; I² = 0%; three RCTs; N = 869). A sensitivity analysis excluding studies at high risk of bias did not change the interpretation of the results for live birth or ongoing pregnancy (OR 0.90, 95% CI 0.66 to 1.25, I² = 0%; two RCTs; N = 744). Our findings suggested that if the rate of live birth or ongoing pregnancy was 36% in the non-metabolomic group, it would be between 32% and 45% with the use of metabolomics.We found low-quality evidence of little or no difference between groups in rates of clinical pregnancy (OR 1.11, 95% CI 0.85 to 1.45; I²= 44%; four trials; N = 924) or multiple pregnancy (OR 1.50, 95% CI 0.70 to 3.19; I² = 0%; two RCTs, N = 180). Rates of cycle cancellation were higher in the metabolomics group (OR 1.78, 95% CI 1.18 to 2.69; I² = 51%; two RCTs; N = 744, low quality evidence). There was very low-quality evidence of little or no difference between groups in rates of ectopic pregnancy rates (OR 3.00, 95% CI 0.12 to 74.07; one RCT; N = 417), and foetal abnormality (no events; one RCT; N = 125). Data were lacking on other adverse effects. A sensitivity analysis excluding studies at high risk of bias did not change the interpretation of the results for clinical pregnancy (OR 1.03, 95% CI 0.76 to 1.38; I² = 40%; two RCTs; N = 744).The overall quality of the evidence ranged from very low to low. Limitations included serious risk of bias (associated with poor reporting of methods, attrition bias, selective reporting, and other biases), imprecision, and inconsistency across trials.

AUTHORS' CONCLUSIONS

According to current trials in women undergoing ART, there is no evidence to show that metabolomic assessment of embryos before implantation has any meaningful effect on rates of live birth, ongoing pregnancy, miscarriage, multiple pregnancy, ectopic pregnancy or foetal abnormalities. The existing evidence varied from very low to low-quality. Data on other adverse events were sparse, so we could not reach conclusions on these. At the moment, there is no evidence to support or refute the use of this technique for subfertile women undergoing ART. Robust evidence is needed from further RCTs, which study the effects on live birth and miscarriage rates for the metabolomic assessment of embryo viability. Well designed and executed trials are also needed to study the effects on oocyte quality and endometrial receptivity, since none are currently available.

Metabolomics for improving pregnancy outcomes in women undergoing assisted reproductive technologies

BACKGROUND

In order to overcome the low effectiveness of assisted reproductive technologies (ART) and the high incidence of multiple births, metabolomics is proposed as a non-invasive method to assess oocyte quality, embryo viability, and endometrial receptivity, and facilitate a targeted subfertility treatment.

OBJECTIVES

To evaluate the effectiveness and safety of metabolomic assessment of oocyte quality, embryo viability, and endometrial receptivity for improving live birth or ongoing pregnancy rates in women undergoing ART, compared to conventional methods of assessment.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Trials Register, CENTRAL, MEDLINE, Embase, CINAHL and two trial registers (November 2016). We also examined the reference lists of primary studies and review articles, citation lists of relevant publications, and abstracts of major scientific meetings.

SELECTION CRITERIA

Randomised controlled trials (RCTs) on metabolomic assessment of oocyte quality, embryo viability, and endometrial receptivity in women undergoing ART.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and risk of bias, and extracted the data. The primary outcomes were rates of live birth or ongoing pregnancy (composite outcome) and miscarriage. Secondary outcomes were clinical pregnancy, multiple and ectopic pregnancy, cycle cancellation, and foetal abnormalities. We combined data to calculate odds ratios (ORs) for dichotomous data and 95% confidence intervals (CIs). Statistical heterogeneity was assessed using the I² statistic. We assessed the overall quality of the evidence for the main comparisons using GRADE methods.

MAIN RESULTS

We included four trials with a total of 802 women, with a mean age of 33 years. All assessed the role of metabolomic investigation of embryo viability. We found no RCTs that addressed the metabolomic assessment of oocyte quality or endometrial receptivity.We found low-quality evidence of little or no difference between metabolomic and non-metabolomic assessment of embryos for rates of live birth or ongoing pregnancy (OR 1.11, 95% CI 0.83 to 1.48; I² = 0%; four RCTs; N = 802), or miscarriage (OR 0.96, 95% CI 0.52 to 1.78; I² = 0%; two RCTs; N = 434). A sensitivity analysis excluding studies at high risk of bias did not change the interpretation of the results for live birth or ongoing pregnancy (OR 0.99, 95% CI 0.71 to 1.38; I² = 0%; two RCTs; N = 621). Our findings suggested that if the rate of live birth or ongoing pregnancy was 36% in the non-metabolomic group, it would be between 32% and 45% with the use of metabolomics.We found low-quality evidence of little or no difference between groups in rates of clinical pregnancy (OR 1.22, 95% CI 0.92 to 1.62; I²= 26%; four trials; N = 802), or multiple pregnancy (OR 1.52, 95% CI 0.71 to 3.23; I² = 0%; two RCTs, N = 181). There was very low-quality evidence of little or no difference between groups in ectopic pregnancy rates (OR 3.37, 95% CI 0.14 to 83.40; one RCT; N = 309), and foetal abnormalities (no events; one RCT; N = 125), and very low-quality evidence of higher rates of cycle cancellation in the metabolomics group (OR 1.78, 95% CI 1.18 to 2.69; I² = 51%; two RCTs; N = 744). Data were lacking on other adverse effects. A sensitivity analysis excluding studies at high risk of bias did not change the interpretation of the results for clinical pregnancy (OR 1.14, 95% CI 0.83 to 1.57; I² = 0%; two RCTs; N = 621).The overall quality of the evidence ranged from very low to low. Limitations included serious risk of bias (associated with poor reporting of methods, attrition bias, selective reporting, and other biases), imprecision, and inconsistency across trials.

AUTHORS' CONCLUSIONS

According to current trials in women undergoing ART, there is insufficient evidence to show that metabolomic assessment of embryos before implantation has any meaningful effect on rates of live birth, ongoing pregnancy, or miscarriage rates. The existing evidence varied from very low to low-quality. Data on adverse events were sparse, so we could not reach conclusions on these. At the moment, there is no evidence to support or refute the use of this technique for subfertile women undergoing ART. Robust evidence is needed from further RCTs, which study the effects on live birth and miscarriage rates for the metabolomic assessment of embryo viability. Well designed and executed trials are also needed to study the effects on oocyte quality and endometrial receptivity, since none are currently available.

Applying metabolomic analyses to the practice of embryology: physiology, development and assisted reproductive technology

The advent of metabolomics technology and its application to small samples has allowed us to non-invasively monitor the metabolic activity of embryos in a complex culture environment. The aim of this study was to apply metabolomics technology to the analysis of individual embryos from several species during in vitro development to gain an insight into the metabolomics pathways used by embryos and their relationship with embryo quality. Alanine is produced by both in vivo- and in vitro-derived human, murine, bovine and porcine embryos. Glutamine is also produced by the embryos of these four species, but only those produced in vitro. Across species, blastocysts significantly consumed amino acids from the culture medium, whereas glucose was not significantly taken up. There are significant differences in the metabolic profile of in vivo- compared with in vitro-produced embryos at the blastocyst stage. For example, in vitro-produced murine embryos consume arginine, asparagine, glutamate and proline, whereas in vivo-produced embryos do not. Human embryos produce more alanine, glutamate and glutamine, and consume less pyruvate, at the blastocyst compared with cleavage stages. Glucose was consumed by human blastocysts, but not at a high enough level to reach significance. Consumption of tyrosine by cleavage stage human embryos is indicative of blastocyst development, although tyrosine consumption is not predictive of blastocyst quality. Similarly, although in vivo-produced murine blastocysts consumed less aspartate, lactate, taurine and tyrosine than those produced in vitro, consumption of these four amino acids by in vitro-derived embryos with high octamer-binding transcription factor 4 (Oct4) expression, indicative of high quality, did not differ from those with low Oct4 expression. Further application of metabolomic technologies to studies of the consumption and/or production of metabolites from individual embryos in a complete culture medium could transform our understanding of embryo physiology and improve our ability to produce developmentally competent embryos in vitro.

Can Comprehensive Chromosome Screening Technology Improve IVF/ICSI Outcomes? A Meta-Analysis

Objective

To examine whether comprehensive chromosome screening (CCS) for preimplantation genetic screening (PGS) has an effect on improving in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) outcomes compared to traditional morphological methods.

Methods

A literature search was conducted in PubMed, EMBASE, CNKI and ClinicalTrials.gov up to May 2015. Two reviewers independently evaluated titles and abstracts, extracted data and assessed quality. We included studies that compared the IVF/ICSI outcomes of CCS-based embryo selection with those of the traditional morphological method. Relative risk (RR) values with corresponding 95% confidence intervals (CIs) were calculated in RevMan 5.3, and subgroup analysis and Begg’s test were used to assess heterogeneity and potential publication bias, respectively.

Results

Four RCTs and seven cohort studies were included. A meta-analysis of the outcomes showed that compared to morphological criteria, euploid embryos identified by CCS were more likely to be successfully implanted (RCT RR 1.32, 95% CI 1.18–1.47; cohort study RR 1.74, 95% CI 1.35–2.24). CCS-based PGS was also related to an increased clinical pregnancy rate (RCT RR 1.26, 95% CI 0.83–1.93; cohort study RR 1.48, 95% CI 1.20–1.83), an increased ongoing pregnancy rate (RCT RR 1.31, 95% CI 0.64–2.66; cohort study RR 1.61, 95% CI 1.30–2.00), and an increased live birth rate (RCT RR 1.26, 95% CI 1.05–1.50; cohort study RR 1.35, 95% CI 0.85–2.13) as well as a decreased miscarriage rate (RCT RR 0.53, 95% CI 0.24–1.15; cohort study RR 0.31, 95% CI 0.21–0.46) and a decreased multiple pregnancy rate (RCT RR 0.02, 95% CI 0.00–0.26; cohort study RR 0.19, 95% CI 0.07–0.51). The results of the subgroup analysis also showed a significantly increased implantation rate in the CCS group.

Conclusions

The effectiveness of CCS-based PGS is comparable to that of traditional morphological methods, with better outcomes for women receiving IVF/ICSI technology. The transfer of both trophectoderm-biopsied and blastomere-biopsied CCS-euploid embryos can improve the implantation rate.

Non-invasive metabolomic profiling of embryo culture media and morphology grading to predict implantation outcome in frozen-thawed embryo transfer cycles

PURPOSE

Assessment of embryo viability is a crucial component of in vitro fertilization and currently relies largely on embryo morphology and cleavage rate. Because morphological assessment remains highly subjective, it can be unreliable in predicting embryo viability. This study investigated the metabolomic profiling of embryo culture media using near-infrared (NIR) spectroscopy for predicting the implantation potential of human embryos in frozen-thawed embryo transfer (FET) cycles.

METHODS

Spent embryo culture media was collected on day 4 after thawed embryo transfer (n = 621) and analysed using NIR spectroscopy. Viability scores were calculated using a predictive multivariate algorithm of fresh embryos with known pregnancy outcomes.

RESULTS

The mean viability indices of embryos resulting in clinical pregnancy following FET were significantly higher than those of non-implanted embryos and differed between the 0, 50, and 100 % implantation groups. Notably, the 0 % group index was significantly lower than the 100 % implantation group index (-0.787 ± 0.382 vs. 1.064 ± 0.331, P < 0.01). To predict implantation outcomes, we examined the area under the ROC curve (AUCROC), which was significantly higher for the viability than for the morphology score (0.94 vs. 0.55; P < 0.01); however, the AUCROCs for the composite and viability scores did not differ significantly (0.92 vs. 0.94; P > 0.05).

CONCLUSIONS

NIR metabolomic profiling of thawed embryo culture media is independent of morphology and correlates with embryo implantation potential in FET cycles. The viability score alone or in conjunction with morphologic grading is a more objective marker for implantation outcome in FET cycles than morphology alone.

Omics as a window to view embryo viability

The advent of advanced omics technologies and the application of these techniques to the analysis of extremely limited material have opened the door to the investigation of embryo physiology in a focused, in-depth approach never before possible. The application of noninvasive metabolomic and proteomic platforms to understanding embryo viability permits the characterization of individual embryos in culture. Initial clinical data have highlighted the promise of these technologies for the development of noninvasive embryo selection criteria. In this way, a complex view of embryo function can be compiled and related to embryo development, quality, and outcome. Application of knowledge gained from omics will transform both our understanding of embryo physiology as well as our ability to select viable embryos for transfer in assisted reproductive technology.

Noninvasive embryo viability assessment by quantitation of human haptoglobin alpha-1 fragment in the in vitro fertilization culture medium: an additional tool to increase success rate

OBJECTIVE

To find new candidate molecules to assess embryo viability in a noninvasive manner.

DESIGN

Prospective, blinded study with randomized sample collection.

SETTING

University research center.

PATIENTS(S)

Ninety embryos implanted in 53 randomly selected patients (mean ± SD age, 32.3 ± 5.1 years) were analyzed.

INTERVENTION(S)

Superovulation treatment was initiated by the administration of the GnRh agonist triptorelin and individual dosages of recombinant FSH. Ovulation was induced by the injection of hCG. Oocytes were fertilized by intracytoplasmic sperm injection.

MAIN OUTCOME MEASURE(S)

Liquid chromatography coupled mass spectrometric quantification of the α-1 fragment of human haptoglobin in the culture medium.

RESULT(S)

A novel polypeptide marker was found that might be helpful to differentiate between potentially viable and nonviable embryos. This molecule was identified with tandem mass spectrometry as the α-1 fragment of human haptoglobin. Significant correlation was found in the amount of the peptide fragment and the outcome of pregnancy. In the culture media of embryos that were assigned in the biochemical assay as nonviable (according to the amount of the haptoglobin fragment), there were no pregnancies detected; this assay revealed a 100% successful selection of the nonviable embryos. In the group assigned as viable, the rate of pregnancy was 54.7%.

CONCLUSION(S)

Viability of the embryo during the IVF process is assessed by microscopic inspection, resulting in a pregnancy rate of 25%-30%. Detection and quantitation of the α-1 haptoglobin fragment of the culture medium proved to be a useful additional method for identifying nonviable embryos, increasing the success rate to 50%.

Biomedical applications of ovarian transvaginal ultrasonography in cattle

Ovarian transvaginal ultrasonography (OTU) has been used world-wide for commercial ovum pick-up programs for in vitro embryo production in elite herds, providing an excellent model for the elucidation of factors controlling bovine oocyte developmental competence. Noninvasive sampling and treatment of ovarian structures is easily accomplished with bovine OTU techniques providing a promising system for in vivo delivery of transgenes directly into the ovary. The current review summarizes existing bovine OTU models and provides prospective applications of bovine OTU to undertake research in reproductive topics of biomedical relevance, with special emphasis on the development of in vivo gene transfer strategies.

An economic assessment of embryo diagnostics (Dx) - the costs of introducing non-invasive embryo diagnostics into IVF standard treatment practices

Background

New techniques in assessing oocytes and embryo quality are currently explored to improve pregnancy and delivery rates per embryo transfer. While a better understanding of embryo quality could help optimize the existing “in vitro fertilization” (IVF) therapy schemes, it is essential to address the economic viability of such technologies in the healthcare setting.

Methods

An Embryo-Dx economic model was constructed to assess the cost-effectiveness of 3 different IVF strategies from a payer’s perspective; it compares Embryo-Dx with single embryo transfer (SET) to elective single embryo transfer (eSET) and to double embryo transfer (DET) treatment practices.

Results

The introduction of a new non-invasive embryo technology (Embryo-Dx) associated with a cost up to €460 is cost-effective compared to eSET and DET based on the cost per live birth. The model assumed that Embryo-Dx will improve ongoing pregnancy rate/realize an absolute improvement in live births of 9% in this case.

Conclusions

This study shows that improved embryo diagnosis combined with SET may have the potential to reduce the cost per live birth per couple treated in IVF treatment practices. The results of this study are likely more sensitive to changes in the ongoing pregnancy rate and consequently the live birth rate than the diagnosis costs. The introduction of a validated Embryo-Dx technology will further support a move towards increased eSET procedures in IVF clinical practice and vice versa.

OMICS: Current and future perspectives in reproductive medicine and technology

Many couples present fertility problems at their reproductive age, and although in the last years, the efficiency of assisted reproduction techniques has increased, these are still far from being 100% effective. A key issue in this field is the proper assessment of germ cells, embryos and endometrium quality, in order to determine the actual likelihood to succeed. Currently available analysis is mainly based on morphological features of oocytes, sperm and embryos and although these strategies have improved the results, there is an urgent need of new diagnostic and therapeutic tools. The emergence of the - OMICS technologies (epigenomics, genomics, transcriptomics, proteomics and metabolomics) permitted the improvement on the knowledge in this field, by providing with a huge amount of information regarding the biological processes involved in reproductive success, thereby getting a broader view of complex biological systems with a relatively low cost and effort.

Metabolomic prediction of pregnancy viability in superovulated cattle embryos and recipients with fourier transform infrared spectroscopy

We analyzed embryo culture medium (CM) and recipient blood plasma using Fourier transform infrared spectroscopy (FTIR) metabolomics to identify spectral models predictive of pregnancy outcome. Embryos collected on Day 6 from superovulated cows in 2 countries were individually cultured in synthetic oviduct fluid medium with BSA for 24 h before embryo transfer. Spent CM, blank controls, and plasma samples (Day 0 and Day 7) were evaluated using FTIR. The spectra obtained were analyzed. The discrimination capability of the classifiers was assessed for accuracy, sensitivity (pregnancy), specificity (nonpregnancy), and area under the ROC curve (AUC). Endpoints considered were Day 60 pregnancy and birth. High AUC was obtained for Day 60 pregnancy in CM within individual laboratories (France AUC = 0.751 ± 0.039, Spain AUC = 0.718 ± 0.024), while cumulative data decreased the AUC (AUC = 0.604  ±  0.029). Predictions for CM at birth were lower than Day 60 pregnancy. Predictions with plasma at birth improved cumulative over individual results (Day 0: France AUC = 0.690 ± 0.044; Spain AUC < 0.55; cumulative AUC = 0.747 ± 0.032). Plasma generally predicted pregnancy and birth better than CM. These first results show that FTIR metabolomics could allow the identification of embryos and recipients with improved pregnancy viability, which may contribute to increasing the efficiency of selection schemes based on ET.

No evidence that embryo selection by near-infrared spectroscopy in addition to morphology is able to improve live birth rates: results from an individual patient data meta-analysis

STUDY QUESTION

What is the value of embryo selection by metabolomic profiling of culture medium with near-infrared (NIR) spectroscopy as an adjunct to morphology, compared with embryo selection by morphology alone, based on an individual patient data meta-analysis (IPD MA)?

SUMMARY ANSWER

The IPD MA indicates that the live birth rate after embryo selection by NIR spectroscopy and morphology is not significantly different compared with the live birth rate after embryo selection by morphology alone.

WHAT IS KNOWN ALREADY

Retrospective proof of principle studies has consistently shown that high NIR viability scores are correlated with a high implantation potential of embryos. However, randomized controlled trials (RCTs) have generally shown no benefit of the NIR technology over embryo morphology, although there have been some conflicting results between pregnancy outcomes on different days of embryo transfer.

STUDY DESIGN, SIZE, DURATION

This IPD MA included all existing RCTs (n = 4) in which embryo selection by morphology was compared with embryo selection by morphology and the use of NIR spectroscopy of spent embryo culture medium by the Viametrics-E(™).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Searches of PubMed, the Cochrane Library and the WHO International Clinical Trials Registry were conducted and the sole manufacturer of the Viametrics-E(™) was consulted to identify clinics where an RCT comparing embryo selection by morphology to embryo selection by morphology and the use of the Viametrics-E(™) (NIR viability score) was performed. A total of 20 citations were potentially eligible for inclusion, two of which met the inclusion criteria. The manufacturer of the Viametrics-E(™) provided two additional clinical sites of use. In total, four RCTs were identified as eligible for inclusion. The IPD MA was based on a fixed effect model due to the lack of heterogeneity between included studies. Differences between study groups were tested and reported using logistic regression models adjusted for significant confounders. The pooled analysis of the primary outcome led to a total sample size of 924 patients: 484 patients in the control group (embryo selection by morphology alone) and 440 patients in the treatment group (embryo selection by morphology plus NIR spectroscopy).

MAIN RESULTS AND THE ROLE OF CHANCE

The live birth rates in the control group and the NIR group were 34.7% (168 of 484) and 33.2% (146 of 440), respectively. The pooled odds ratio (OR) was 0.98 [95% confidence interval (CI) 0.74-1.29], indicating no difference in live birth rates between the two study groups. The data of the four studies showed no significant heterogeneity (I(2) = 26.2% P = 0.26). The multivariate regression analysis including all confounders show that maternal age (OR 0.90, 95% CI 0.87-0.94) and the number of previous IVF cycles (OR 0.83, 95% CI 0.71-0.96) were significantly related to live birth. The study group (i.e. embryo selection by morphology or embryo selection by morphology plus NIR) was not related to live birth (OR 0.97, 95% CI 0.73-1.29).

LIMITATIONS AND REASONS FOR CAUTION

The availability of at least two similar best quality embryos as an inclusion criterion prior to transfer in the two largest RCTs might have caused a selection bias towards a better prognosis patient group.

WIDER IMPLICATIONS OF THE FINDINGS

There is at present no evidence that NIR spectroscopy of spent embryo culture media in its current form can be used in daily practice to improve live birth rates.

Assisted reproductive techniques

Assisted reproductive technologies (ART) encompass fertility treatments, which involve manipulations of both oocyte and sperm in vitro. This chapter provides a brief overview of ART, including indications for treatment, ovarian reserve testing, selection of controlled ovarian hyperstimulation (COH) protocols, laboratory techniques of ART including in vitro fertilization (IVF), and intracytoplasmic sperm injection (ICSI), embryo transfer techniques, and luteal phase support. This chapter also discusses potential complications of ART, namely ovarian hyperstimulation syndrome (OHSS) and multiple gestations, and the perinatal outcomes of ART.

Non-invasive metabolomic analysis using a commercial NIR instrument for embryo selection

CONTEXT:

Metabolomics was introduced in human in vitro fertilization (IVF) for noninvasive identification of viable embryos with the highest developmental competence.

AIMS:

To determine whether embryo selection using a commercial version of metabolomic analysis leads to increased implantation rates (IRs) with fetal cardiac activity (FCA) compared with morphology evaluation alone.

SETTING AND DESIGN:

Randomized controlled trial from April to December 2010 at a private IVF unit. The study was terminated prematurely due to the market withdrawal of the instrument.

MATERIALS AND METHODS:

IVF patients ≥18 and ≤43 years with ≥4 × 2PN were randomly allocated to metabolomic analysis combined with embryo morphology (ViaMetrics-E; metabolomics + morphology group) or embryo morphology alone (morphology group). Cycles with frozen embryos, oocyte donations, or testicular biopsy were excluded.

STATISTICAL ANALYSIS:

Categorical and continuous data were analyzed for statistical significance using 2-tailed Fisher's exact test and t-test, respectively. Statistical significance was accepted when P > 0.05.

RESULTS:

A total of 125 patients were included in the study; 39 patients were allocated to metabolomics + morphology group and 86 patients to morphology group. Patients were stratified according to the day of embryo transfer (Days 2, 3, or 5). IRs with FCA were similar for Days 2 and 3 transfers in both groups. For Day 5 transfers, IRs with FCA were significantly higher in the metabolomics + morphology group (46.8% vs. 28.9%; P = 0.041; 95% confidence intervalp [CI]: 1.09-34.18). Pregnancy and live births rates were similar for Days 2, 3, and 5 in both groups. The study was terminated early following the voluntary market withdrawal of ViaMetrics-E in December 2010.

CONCLUSIONS:

Metabolomic analysis using the commercial near-infrared (NIR) instrument does not appear to have a beneficial effect on pregnancy and live births, with improvement in IR with FCA for Day 5 transfers. However, no solid conclusions can be reached due to the lack of adequate study power.ClinicalTrials.gov Identifier: NCT01490515

Metabolic profiling of human follicular fluid identifies potential biomarkers of oocyte developmental competence

The use of metabolomic based techniques to aid oocyte and embryo selection has gained attention in recent years. Previous work from our laboratory has demonstrated that the (1)H NMR-based metabolic profile of follicular fluid correlates with oocyte developmental potential. Patients undergoing IVF at the Merrion Fertility Clinic had follicular fluid collected at the time of oocyte retrieval. The fatty acid composition of follicular fluid from follicles where oocytes fertilised and developed into multi-cell embryos (n=15) and from oocytes that fertilised normally but failed to cleave (n=9) (cleaved vs non-cleaved) was compared. Statistical analysis was performed on the data using univariate and multivariate techniques. Analysis of the fatty acid composition revealed that there were nine fatty acids significantly different between follicular fluid from the cleaved and the non-cleaved sample groups. Of particular interest were the higher concentration of total saturated (P=0.03) and the lower concentration of total polyunsaturated fatty acids in the non-cleaved sample group (P=0.001). Random forest classification models were used to predict successful cleavage in follicular fluid samples producing models with errors rates of <10%. Receiver operating characteristic analysis demonstrated that the model had good predictability with an area under the curve of 0.96. The panel of fatty acid biomarkers identified in this study indicates that the fatty acid composition of follicular fluid may be more predictive in comparison to other previously identified biomarkers. Following validation in a larger cohort, these biomarkers may have the potential to be used in fertility clinics to aid the selection of oocytes in the future.

New approaches to embryo selection

Embryo selection has been an important topic since the introduction of assisted reproduction, with embryo morphology being the most obvious criterion. Although morphology serves as indicator for overall IVF laboratory quality, its statistical assessment limits the possibility to identify the most implantation-competent embryos. In order to reach a direct picture of the developing embryo, invasive procedures such as preimplantation genetic screening or transcriptome and proteome analysis of biopsied embryonic tissue were initially prioritized and are still under investigation. More recently, focus has shifted towards noninvasive techniques that maintain the integrity of the embryo. Metabolomic profiling of culture medium from growing embryos attracted much research. Although successful in a pilot study, that approach failed in a randomized controlled trial. Other metabolomics studies are on their way but not yet available for routine clinical use. The most promising strategy at present is the combined evaluation of morphology and developmental kinetics using time-lapse imaging. This has brought new insights into certain characteristics that enable deselection of embryos at an early stage of development and to identify others with high potential for successful implantation. However, there is still considerable room for improvement. Further strategies will most likely involve the combination of several different approaches.

Prediction of embryo implantation potential by mass spectrometry fingerprinting of the culture medium

This study has evaluated the performance of a multivariate statistical model to predict embryo implantation potential by processing data from the chemical fingerprinting of culture medium samples used for human embryo culture. The culture medium for 113 embryos from 55 patients undergoing ICSI was collected after embryo transfer. The samples were split into positive (n=29) and negative (n=84) implantation groups according their implantation outcomes (100% or 0% implantation). The samples were individually diluted and analyzed by electrospray ionization mass spectrometry (ESI-MS). The m/z ratios and relative abundances of the major ions in each spectrum were considered for partial least square discriminant analysis. Data were divided into two subsets (calibration and validation), and the models were evaluated and applied to the validation set. A total of 5987 ions were observed in the groups. The multivariate statistical model described more than 82% of the data variability. Samples of the positive group were correctly identified with 100% probability and negative samples with 70%. The culture media used for embryos that were positive or negative for successful implantation showed specific biochemical signatures that could be detected in a fast, simple, and noninvasive way by ESI-MS. To our knowledge, this is the first report that uses MS fingerprinting to predict human embryo implantation potential. This biochemical profile could help the selection of the most viable embryo, improving single-embryo transfer and thus eliminating the risk and undesirable outcomes of multiple pregnancies.

In vitro fertilisation treatment and factors affecting success

The efficacy of assisted reproductive technologies has improved significantly over the past decades. The main indications for in vitro fertilisation include tubal obstruction, severe male-factor infertility, severe endometriosis, ovulatory dysfunction, diminished ovarian reserve, and infertility of unexplained cause. In vitro fertilisation has also become an effective treatment option for couples wishing to undergo pre-implantation genetic diagnosis or screening, and for those wishing to cryopreserve their oocytes or embryos for preservation of fertility. The management of women in late reproductive age poses a major challenge; the optimum in vitro fertilisation treatment for poor responders remains elusive. The success of in vitro fertilisation treatment can be optimised by taking an individualised, patient-centered approach to controlled ovarian hyperstimulation. Key components involve selection of an appropriate controlled ovarian protocol, close-cycle monitoring, adjustment of gonadotropin dosage to avoid hyper-response, and individualised timing of human chorionic gonadotropin injection. Future directions of assisted reproductive technologies include development of non-invasive embryo selection methods, use of transcriptomics, proteomics, metabolomics, and time-lapse imaging technologies.

Time-dependent O2 consumption patterns determined optimal time ranges for selecting viable human embryos

OBJECTIVE

To evaluate correlations between metabolic activity and implantation potential of transferred embryos in a study based on oxygen (O(2)) consumption (OC) measurements, because O(2) uptake is directly related to the capacity of an embryo to produce energy via adenosine triphosphate.

DESIGN

Retrospective cohort study.

SETTING

Infertility institute.

PATIENT(S)

Five hundred seventy-five injected oocytes in 56 first oocyte donation cycles with embryo transfer on day 3.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

We analyzed embryo destination viability and implantation depending on the embryo OC rate obtained from 47,741 measurements (up to 85 measurements per embryo, 2-3 measurements per hour). OC patterns were analyzed in relation to the time elapsed from sperm microinjection, to the final destination of the embryos (transferred, frozen, or discarded), to ongoing pregnancy, and by successful implantation.

RESULT(S)

OC was found to decrease during embryonic development. OC patterns from 52 hours onward showed the strongest correlation with implantation success. Regarding embryo destination, the same patterns were observed.

CONCLUSION(S)

OC from individual embryos revealed significant differences, mainly close to the time of transfer, when OC pattern was associated with successful implantation. Therefore, measuring the OC pattern of human embryos culture up to 72 hours could be used to select the embryo with best developmental potential.

Culture systems: embryo density

Embryo density is defined as the embryo-to-volume ratio achieved during in vitro culture; in other words, it is the number of embryos in a defined volume of culture medium. The same density can be achieved by manipulating either the number of embryos in a given volume of medium, or manipulating the volume of the medium for a given number of embryos: for example, a microdrop with five embryos in a 50 μl volume under oil has the same embryo-to-volume ratio (1:10 μl) as a microdrop with one embryo in a 10 μl volume under oil (1:10 μl). Increased embryo density can improve mammalian embryo development in vitro; however, the mechanism(s) responsible for this effect may be different with respect to which method is used to increase embryo density.Standard, flat sterile plastic petri dishes are the most common, traditional platform for embryo culture. Microdrops under a mineral oil overlay can be prepared to control embryo density, but it is critical that dish preparation is consistent, where appropriate techniques are applied to prevent microdrop dehydration during preparation, and results of any data collection are reliable, and repeatable. There are newer dishes available from several manufacturers that are specifically designed for embryo culture; most are readily available for use with human embryos. The concept behind these newer dishes relies on fabrication of conical and smaller volume wells into the dish design, so that embryos rest at the lowest point in the wells, and where putative embryotrophic factors may concentrate.Embryo density is not usually considered by the embryologist as a technique in and of itself; rather, the decision to culture embryos in groups or individually is protocol-driven, and is based more on convenience or the need to collect data on individual embryos. Embryo density can be controlled, and as such, it can be utilized as a simple, yet effective tool to improve in vitro development of human embryos.

Oxidative parameters of embryo culture media may predict treatment outcome in in vitro fertilization: a novel applicable tool for improving embryo selection

OBJECTIVE

To examine whether the oxidative status of an individual embryo before transfer may predict chances of implantation.

DESIGN

A prospective laboratory study.

SETTING

An IVF unit in a university-affiliated hospital.

PATIENT(S)

One hundred thirty-three women undergoing IVF-ET treatment cycles.

INTERVENTION(S)

Before ET, 10 μL of embryo culture medium was retrieved individually from each embryo and the oxidative status assessed by the thermochemiluminescence (TCL) analyzer.

MAIN OUTCOME MEASURE(S)

The occurrence of pregnancy. Two parameters were recorded: the TCL amplitude after 50 seconds (H1) and the TCL ratio. These were compared with demographic, clinical, and laboratory parameters and treatment outcome. All data underwent statistical analysis.

RESULT(S)

Altogether 284 embryos were transferred in 133 ET cycles. Forty-one pregnancies occurred (31%). For embryos transferred after 72 hours (77 transfers), the highest H1 levels in each group of transferred embryos correlated with the occurrence of pregnancy. The combination of maximal intracohort H1 level <210 counts per second with a TCL ratio of ≤ 80% had a positive predictive value of 70.6% for the occurrence of pregnancy.

CONCLUSION(S)

The oxidative status of the early embryo in IVF is associated with the chances of implantation. Assessment of the oxidative status of embryos in culture media before transfer may serve as an applicable tool for improving embryo selection in light of the legal limitations of the number of transferred embryos allowed.

Association between amino acid turnover and chromosome aneuploidy during human preimplantation embryo development in vitro

This study investigated the relationship between human preimplantation embryo metabolism and aneuploidy rates during development in vitro. One hundred and eighty-eight fresh and cryopreserved embryos from 59 patients (33.9 +/- 0.6 years) were cultured for 2-5 days. The turnover of 18 amino acids was measured in spent media by high-performance liquid chromatography. Embryos were either fixed for interphase fluorescent in situ hybridization analysis of chromosomes 13, 18, 19, 21, X or Y, or were assayed for mitochondrial activity. Amino acid turnover was different (P < 0.05) between stage-matched fresh and cryopreserved embryos due to blastomere loss following warming. The proportion of embryos with aneuploid cells increased as cell division progressed from pronucleate- (23%) to late cleavage stages (50-70%). Asparagine, glycine and valine turnover was significantly different between uniformly genetically normal and uniformly abnormal embryos on Days 2-3 of culture. By Days 3-4, the profiles of serine, leucine and lysine differed between uniformly euploid versus aneuploid embryos. Gender significantly (P < 0.05) affected the metabolism of tryptophan, leucine and asparagine by cleavage-stage embryos. Pronucleate zygotes had a significantly higher proportion of active:inactive mitochondria compared with cleavage-stage embryos. Furthermore, mitochondrial activity was correlated (P < 0.05) with altered aspartate and glutamine turnover. These results demonstrate the association between the metabolism, cytogenetic composition and health of human embryos in vitro.

Preimplantation mouse embryo selection guided by light-induced dielectrophoresis

Selection of optimal quality embryos for in vitro fertilization (IVF) transfer is critical to successful live birth outcomes. Currently, embryos are chosen based on subjective assessment of morphologic developmental maturity. A non-invasive means to quantitatively measure an embryo's developmental maturity would reduce the variability introduced by the current standard. We present a method that exploits the scaling electrical properties of pre-transfer embryos to quantitatively discern embryo developmental maturity using light-induced dielectrophoresis (DEP). We show that an embryo's DEP response is highly correlated with its developmental stage. Uniquely, this technique allows one to select, in sequence and under blinded conditions, the most developmentally mature embryos among a mixed cohort of morphologically indistinguishable embryos cultured in optimized and sub-optimal culture media. Following assay, embryos continue to develop normally in vitro. Light-induced dielectrophoresis provides a non-invasive, quantitative, and reproducible means to select embryos for applications including IVF transfer and embryonic stem cell harvest.

Follicular fluid content and oocyte quality: from single biochemical markers to metabolomics

The assessment of oocyte quality in human in vitro fertilization (IVF) is getting increasing attention from embryologists. Oocyte selection and the identification of the best oocytes, in fact, would help to limit embryo overproduction and to improve the results of oocyte cryostorage programs. Follicular fluid (FF) is easily available during oocyte pick-up and theorically represents an optimal source on non-invasive biochemical predictors of oocyte quality. Unfortunately, however, the studies aiming to find a good molecular predictor of oocyte quality in FF were not able to identify substances that could be used as reliable markers of oocyte competence to fertilization, embryo development and pregnancy. In the last years, a well definite trend toward passing from the research of single molecular markers to more complex techniques that study all metabolites of FF has been observed. The metabolomic approach is a powerful tool to study biochemical predictors of oocyte quality in FF, but its application in this area is still at the beginning. This review provides an overview of the current knowledge about the biochemical predictors of oocyte quality in FF, describing both the results coming from studies on single biochemical markers and those deriving from the most recent studies of metabolomics.

Metabolomic assessment of oocyte viability

The aim of the current study was to evaluate whether near-infrared (NIR) spectroscopy-generated metabolomic data obtained from oocyte culture samples would correlate with nuclear maturity status and derived embryo development. A total of 412 oocyte culture samples were collected from 43 patient cycles. Metabolomic profiles of metaphase I and II oocytes were obtained by NIR spectroscopy and were significantly different from each other and from profiles of prophase I (germinal vesicle) oocytes (P +/- 0.001 at the 95% confidence interval). Additionally, NIR spectroscopic analysis of culture medium of oocytes that developed to grade A embryos on day 3 demonstrated significantly higher viability indices (0.62 +/- 0.23) than those that developed to grades C/D (0.42 +/- 0.26; P < 0.006); and on day 5 grade A (0.37 +/- 0.20) was also higher than grades C/D (0.14 +/- 0.21; P < 0.02). Metabolomic profiles of oocytes that resulted in pregnancy had higher viability indices (0.87 +/- 0.27) than those that did not (0.44 +/- 0.17; P < 0.0001). The results of the current study demonstrate that metabolomic profiling from spent culture medium of the oocyte is related to nuclear maturity, is able to predict embryo development at day 3 and day 5 stages, and relates to embryo viability.