(1)H NMR based metabolic profiling of day 2 spent embryo media correlates with implantation potential

Development of a Novel Non-invasive Metabolomics Assay to Predict Implantation Potential of Human Embryos

Can a set of metabolites present in embryo culture media correlate with embryo implantation? Case-control study in two phases: discovery phase (101 samples) and validation phase (169 samples), collected between 2018 and 2022, with a total of 218 participants. Culture media samples with known implantation outcomes were collected after blastocyst embryo transfer (including both PGT and non-PGT cycles) and were analyzed using chromatography followed by mass spectrometry. The spectra were processed and analyzed using statistical and machine learning techniques to identify biomarkers associated with embryo implantation, and to develop a predictive model. In the discovery phase, 148 embryo implantation biomarkers were identified using high resolution equipment, and 47 of them were characterized. Our results indicate a significant enrichment of tryptophan metabolism, arginine and proline metabolism, and lysine degradation biochemical pathways. After transferring the method to a lower resolution equipment, a model able to assign a Metabolite Pregnancy Index (MPI) to each embryo culture media was developed, taking the concentration of 36 biomarkers as input. Applying this model to 20% of the validation samples (N=34) used as the test set, an accuracy of 85.29% was achieved, with a PPV (Positive Predictive Value) of 88% and a NPV (Negative Predictive Value) of 77.78%. Additionally, informative results were obtained for all the analyzed samples. Metabolite concentration in the media after in vitro culture shows correlation with embryo implantation potential. Furthermore, the mathematical combination of biomarker concentrations using Artificial Intelligence techniques can be used to predict embryo implantation outcome with an accuracy of around 85%.

Differential sperm histone retention in normozoospermic ejaculates of infertile men negatively affects sperm functional competence and embryo quality

BACKGROUND

The unique epigenetic architecture that sperm cells acquire during spermiogenesis by retaining <15% of either canonical or variant histone proteins in their genome is essential for normal embryogenesis. Whilst heterogeneous levels of retained histones are found in morphologically normal spermatozoa, their effect on reproductive outcomes is not fully understood.

METHODS

Processed spermatozoa (n = 62) were tested for DNA integrity by sperm chromatin dispersion assay, and retained histones were extracted and subjected to dot-blot analysis. The impact of retained histone modifications in normozoospermic patients on sperm functional characteristics, embryo quality, metabolic signature in embryo spent culture medium and pregnancy outcome was studied.

RESULTS

Dot-blot analysis showed heterogeneous levels of retained histones in the genome of normozoospermic ejaculates. Post-wash sperm yield was affected by an increase in H3K27Me3 and H4K20Me3 levels in the sperm chromatin (p < 0.05). Also, spermatozoa with higher histone H3 retention had increased DNA damage (p < 0.05). Spermatozoa from these cohorts, when injected into donor oocytes, correlated to a significant decrease in the fertilisation rate with an increase in sperm histone H3 (p < 0.05) and H3K27Me3 (p < 0.01). An increase in histone H3 negatively affected embryo quality (p < 0.01) and clinical pregnancy outcome post-embryo transfer (p < 0.05). On the other hand, spent culture medium metabolites assessed by high-resolution (800 MHz) nuclear magnetic resonance showed an increased intensity of the amino acid methionine in the non-pregnant group than in the pregnant group (p < 0.05) and a negative correlation with sperm histone H3 in the pregnant group (p < 0.05).

DISCUSSION AND CONCLUSION

Histone retention in spermatozoa can be one of the factors behind the development of idiopathic male infertility. Such spermatozoa may influence embryonic behaviour and thereby affect the success rate of assisted reproductive technology procedures. These results, although descriptive in nature, warrant further research to address the underlying mechanisms behind these clinically important observations.

Metabolomics Integration in Assisted Reproductive Technologies for Enhanced Embryo Selection beyond Morphokinetic Analysis

Embryo quality evaluation during in vitro development is a crucial factor for the success of assisted reproductive technologies (ARTs). However, the subjectivity inherent in the morphological evaluation by embryologists can introduce inconsistencies that impact the optimal embryo choice for transfer. To provide a more comprehensive evaluation of embryo quality, we undertook the integration of embryo metabolomics alongside standardized morphokinetic classification. The culture medium of 55 embryos (derived from 21 couples undergoing ICSI) was collected at two timepoints (days 3 and 5). Samples were split into Good (n = 29), Lagging (n = 19), and Bad (n = 10) according to embryo morphokinetic evaluation. Embryo metabolic performance was assessed by monitoring the variation in specific metabolites (pyruvate, lactate, alanine, glutamine, acetate, formate) using 1H-NMR. Adjusted metabolite differentials were observed during the first 3 days of culture and found to be discriminative of embryo quality at the end of day 5. Pyruvate, alanine, glutamine, and acetate were major contributors to this discrimination. Good and Lagging embryos were found to export and accumulate pyruvate and glutamine in the first 3 days of culture, while Bad embryos consumed them. This suggests that Bad embryos have less active metabolic activity than Good and Lagging embryos, and these two metabolites are putative biomarkers for embryo quality. This study provides a more comprehensive evaluation of embryo quality and can lead to improvements in ARTs by enabling the selection of the best embryos. By combining morphological assessment and metabolomics, the selection of high-quality embryos with the potential to result in successful pregnancies may become more accurate and consistent.

Prediction model for day 3 embryo implantation potential based on metabolites in spent embryo culture medium

BACKGROUND

Metabolites in spent embryo culture medium correlate with the embryo's viability. However, there is no widely accepted method using metabolite dada to predict successful implantation. We sought to combine metabolomic profiling of spent embryo culture medium and clinical variables to create an implantation prediction model as an adjunct to morphological screening of day 3 embryos.

METHODS

This investigation was a prospective, nested case-control study. Forty-two day 3 embryos from 34 patients were transferred, and the spent embryo culture medium was collected. Twenty-two embryos implanted successfully, and the others failed. Metabolites in the medium relevant to implantation were detected and measured by Liquid Chromatography-Mass Spectrometry. Clinical signatures relevant to embryo implantation were subjected to univariate analysis to select candidates for a prediction model. Multivariate logistical regression of the clinical and metabolomic candidates was used to construct a prediction model for embryo implantation potential.

RESULTS

The levels of 13 metabolites were significantly different between the successful and failed groups, among which five were most relevant and interpretable selected by Least Absolute Shrinkage and Selection Operator regression analysis. None of the clinical variables significantly affected day 3 embryo implantation. The most relevant and interpretable set of metabolites was used to construct a prediction model for day 3 embryo implantation potential with an accuracy of 0.88.

CONCLUSIONS

Day 3 embryos'implantation potential could be noninvasively predicted by the spent embryo culture medium's metabolites measured by LC-MS. This approach may become a useful adjunct to morphological evaluation of day 3 embryos.

Combining Machine Learning with Metabolomic and Embryologic Data Improves Embryo Implantation Prediction

This study investigated whether combining metabolomic and embryologic data with machine learning (ML) models improve the prediction of embryo implantation potential. In this prospective cohort study, infertile couples (n=56) undergoing day-5 single blastocyst transfer between February 2019 and August 2021 were included. After day-5 single blastocyst transfer, spent culture medium (SCM) was subjected to metabolite analysis using nuclear magnetic resonance (NMR) spectroscopy. Derived metabolite levels and embryologic parameters between successfully implanted and failed groups were incorporated into ML models to explore their predictive potential regarding embryo implantation. The SCM of blastocysts that resulted in successful embryo implantation had significantly lower pyruvate (p<0.05) and threonine (p<0.05) levels compared to medium control but not compared to SCM related to embryos that failed to implant. Notably, the prediction accuracy increased when classical ML algorithms were combined with metabolomic and embryologic data. Specifically, the custom artificial neural network (ANN) model with regularized parameters for metabolomic data provided 100% accuracy, indicating the efficiency in predicting implantation potential. Hence, combining ML models (specifically, custom ANN) with metabolomic and embryologic data improves the prediction of embryo implantation potential. The approach could potentially be used to derive clinical benefits for patients in real-time.

NMR-based metabonomics reveals the dynamic effect of electro-acupuncture on central nervous system in gastric mucosal lesions (GML) rats

BACKGROUND

Gastric mucosal lesions (GML) are common in gastric diseases and seriously affect the quality of life. There are inevitable side effects in drug therapy. Acupuncture is an important part of traditional Chinese medicine. Electro-acupuncture (EA) has unique curative effect in treatment of GML. However, there are still few reports on the central mechanism of electro-acupuncture in treatment of GML. In this study, NMR metabonomics was used to explore the central metabolic change mechanism of electro-acupuncture in treatment of GML.

METHODS

SD rats were randomly divided into Control, GML and EA groups. According to different intervention time, each group was further divided into 3 subgroups. This study mainly established GML model rats by 75% ethanol. Dynamic expressions of metabolites in cerebral cortex and medulla were observed by 1D ¹H Nuclear Magnetic Resonance (NMR) metabolomics, combined with gastric mucosal histopathological examination to evaluate the time-effect relationship of electro-acupuncture at Zusanli (ST36) and Liangmen (ST21) points for 1 day, 4 days and 7 days treatment of GML.

RESULTS

The results showed that the repair effect of electro-acupuncture on gastric mucosal injury was the most obvious in 4 days and stable in 7 days, and 4 days electro-acupuncture can effectively inhibit GML gastric mucosal inflammation and the expression of inflammatory cells. Meanwhile, the NMR spectrum results of medulla and cerebral cortex showed that, 21 potential metabolites were identified to participate in the mechanism of pathogenesis of GML and the regulation of electro-acupuncture, including 15 in medulla and 10 in cerebral cortex. Metabolic pathway analysis showed that the differential metabolites involved 19 metabolic pathways, which could be divided into energy, neurotransmitters, cells and cell membrane and antioxidation according to their functions. The correlation analysis of stomach, medulla and cerebral cortex shows that the stimulation signal of GML may reach the cerebral cortex from the stomach through medulla, and electro-acupuncture can treat GML by regulating the central nervous system (CNS).

CONCLUSIONS

4 days electro-acupuncture treatment can significantly improve gastric mucosal injury, and the curative effect tends to be stable in 7 days treatment. Meanwhile, the pathogenesis of GML and the efficacy of electro-acupuncture involve metabolic pathways such as energy, neurotransmitters, cells and antioxidation, and electro-acupuncture can treat GML by regulating CNS.

LC-MS Analysis Revealed the Significantly Different Metabolic Profiles in Spent Culture Media of Human Embryos with Distinct Morphology, Karyotype and Implantation Outcomes

In this study we evaluated possible differences in metabolomic profiles of spent embryo culture media (SECM) of human embryos with distinct morphology, karyotype, and implantation outcomes. A total of 153 samples from embryos of patients undergoing in vitro fertilization (IVF) programs were collected and analyzed by HPLC-MS. Metabolomic profiling and statistical analysis revealed clear clustering of day five SECM from embryos with different morphological classes and karyotype. Profiling of day five SECM from embryos with different implantation outcomes showed 241 significantly changed molecular ions in SECM of successfully implanted embryos. Separate analysis of paired SECM samples on days three and five revealed 46 and 29 molecular signatures respectively, significantly differing in culture media of embryos with a successful outcome. Pathway enrichment analysis suggests certain amino acids, vitamins, and lipid metabolic pathways to be crucial for embryo implantation. Differences between embryos with distinct implantation potential are detectable on the third and fifth day of cultivation that may allow the application of culture medium analysis in different transfer protocols for both fresh and cryopreserved embryos. A combination of traditional morphological criteria with metabolic profiling of SECM may increase implantation rates in assisted reproductive technology programs as well as improve our knowledge of the human embryo metabolism in the early stages of development.

Solution NMR in human embryo culture media as an option for assessment of embryo implantation potential

NMR offers the potential to holistically screen hundreds of metabolites and has already proved to be a powerful technique able to provide a global picture of metabolic changes in a wide range of biological systems underlying complex and multifactorial matrixes. This review covers the literature until May 2020 centered on the early prediction of the viability of in vitro developed embryos using several analytical techniques, including NMR. Nowadays, the predominant non-invasive technique for selecting viable embryos is based on morphology, where variables associated with the rate of cleavage and blastocyst formation are evaluated by the embryologist following standardized criteria that are somewhat subjective. This morphological approach is therefore inadequate for the prediction of embryo quality, and several studies have focused on developing new non-invasive methods using molecular approaches based particularly on metabolomics. This review outlines the potential of NMR as one of these non-invasive in vitro methods based on the analysis of spent embryo culture media.

Metabolomics analysis of follicular fluid coupled with oocyte aspiration reveals importance of glucocorticoids in primate periovulatory follicle competency

Gonadotropin administration during infertility treatment stimulates the growth and development of multiple ovarian follicles, yielding heterogeneous oocytes with variable capacity for fertilization, cleavage, and blastocyst formation. To determine how the intrafollicular environment affects oocyte competency, 74 individual rhesus macaque follicles were aspirated and the corresponding oocytes classified as failed to cleave, cleaved but arrested prior to blastulation, or those that formed blastocysts following in vitro fertilization. Metabolomics analysis of the follicular fluid (FF) identified 60 unique metabolites that were significantly different between embryo classifications, of which a notable increase in the intrafollicular ratio of cortisol to cortisone was observed in the blastocyst group. Immunolocalization of the glucocorticoid receptor (GR, NR3C1) revealed translocation from the cytoplasm to nucleus with oocyte maturation in vitro and, correlation to intrafollicular expression of the 11-hydroxy steroid dehydrogenases that interconvert these glucocorticoids was detected upon an ovulatory stimulus in vivo. While NR3C1 knockdown in oocytes had no effect on their maturation or fertilization, expansion of the associated cumulus granulosa cells was inhibited. Our findings indicate an important role for NR3C1 in the regulation of follicular processes via paracrine signaling. Further studies are required to define the means through which the FF cortisol:cortisone ratio determines oocyte competency.

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.

The utility of nuclear magnetic resonance spectroscopy in assisted reproduction

Infertility affects approximately 15-20% of individuals of reproductive age worldwide. Over the last 40 years, assisted reproductive technology (ART) has helped millions of childless couples. However, ART is limited by a low success rate and risk of multiple gestations. Devising methods for selecting the best gamete or embryo that increases the ART success rate and prevention of multiple gestation has become one of the key goals in ART today. Special emphasis has been placed on the development of non-invasive approaches, which do not require perturbing the embryonic cells, as the current morphology-based embryo selection approach has shortcomings in predicting the implantation potential of embryos. An observed association between embryo metabolism and viability has prompted researchers to develop metabolomics-based biomarkers. Nuclear magnetic resonance (NMR) spectroscopy provides a non-invasive approach for the metabolic profiling of tissues, gametes and embryos, with the key advantage of having a minimal sample preparation procedure. Using NMR spectroscopy, biologically important molecules can be identified and quantified in intact cells, extracts or secretomes. This, in turn, helps to map out the active metabolic pathways in a system. The present review covers the contribution of NMR spectroscopy in assisted reproduction at various stages of the process.

Reducing time to pregnancy and facilitating the birth of healthy children through functional analysis of embryo physiology†

An ever-increasing number of couples rely on assisted reproductive technologies (ART) in order to conceive a child. Although advances in embryo culture have led to increases in the success rates of clinical ART, it often takes more than one treatment cycle to conceive a child. Ensuring patients conceive as soon as possible with a healthy embryo is a priority for reproductive medicine. Currently, selection of embryos for transfer relies predominantly on the morphological assessment of the preimplantation embryo; however, morphology is not an absolute link to embryo physiology, nor the health of the resulting child. Non-invasive quantitation of individual embryo physiology, a key regulator of both embryo viability and health, could provide valuable information to assist in the selection of the most viable embryo for transfer, hence reducing the time to pregnancy. Further, according to the Barker Hypothesis, the environment to which a fetus is exposed to during gestation affects subsequent offspring health. If the environment of the preimplantation period is capable of affecting metabolism, which in turn will affect gene expression through the metaboloepigenetic link, then assessment of embryo metabolism should represent an indirect measure of future offspring health. Previously, the term viable embryo has been used in association with the potential of an embryo to establish a pregnancy. Here, we propose the term healthy embryo to reflect the capacity of that embryo to lead to a healthy child and adult.

Comparison between embryos transferred with self-spent and fresh medium on reproductive outcomes: a prospective randomized trial

As the final and critical step in in vitro fertilization (IVF), embryo transfer has always received much attention and deserves continuous optimization. In the present study, to explore the role of autocrine factors in embryo self-spent culture media, we prospectively compared embryo transfer with self-spent culture medium and fresh medium on clinical pregnancy outcomes. A total of 318 fresh IVF/intracytoplasmic sperm injection (ICSI) cycles were randomly allocated into two subgroups based on their transfer media (using a self-spent culture medium or new pre-equilibrated culture media), and the clinical outcomes were compared between groups. The implantation rates, clinical pregnancy rates and live birth rates for transfer using self-spent medium instead of new pre-equilibrated culture medium were slightly improved without statistical significance. Interestingly, however, biochemical pregnancy rate was found to be significantly decreased after transfer using self-spent medium for Day 3 embryos compared with new pre-equilibrated culture media. In short, embryo transfer with self-spent culture medium has shown some advantages, and large sample size studies are still needed to confirm these observations.

ABBREVIATIONS

ART: assisted reproductive technologies; ICSI: intracytoplasmic sperm injection; IVF: in vitro fertilization; ET: embryo transfer.

Dynamic observation and analysis of metabolic response to moxibustion stimulation on ethanol-induced gastric mucosal lesions (GML) rats

Background

Gastric mucosal lesion (GML) is the initiating pathological process in many refractory gastric diseases. And moxibustion is an increasingly popular alternative therapy that prevents and treats diseases. However, there are few published reports about developing pathology of GML and therapeutic mechanism of moxibustion treatment on GML. In this study, we investigated pathology of GML and therapeutic mechanism of moxibustion treatment on GML.

Methods

The male Sprague-Dawley (SD) rats were induced by intragastric administration of 75% ethanol after fasting for 24 h and treated by moxibustion at Zusanli (ST36) and Liangmen (ST21) for 1 day, 4 days or 7 days. Then we applied ¹H NMR-based metabolomics to dynamic analysis of metabolic profiles in biological samples (stomach, cerebral cortex and medulla). And the conventional histopathological examinations as well as metabolic pathways assays were also performed.

Results

Moxibustion intervention showed a beneficial effect on GML by modulating comprehensive metabolic alterations caused by GML, including energy metabolism, membrane metabolism, cellular active and neurotransmitters function.

Conclusions

Moxibustion can effectively treat gastric mucosal damage and effectively regulate the concentration of some related differential metabolites to maintain the stability of the metabolic pathway.

Non-invasive nuclear magnetic resonance analysis of male and female embryo metabolites during in vitro embryo culture

INTRODUCTION

In the past 20+ years, several studies of bovine embryo production showed how the ratio of male to female embryos changes if embryos are made in vivo or in vitro. It is known that in in vitro systems, the sex ratio is in favor of males when there are high levels of glucose, and favors females when the principal energetic substrate is one other than glucose, like citrate.

OBJECTIVES

The aim of this study was to evaluate the embryo metabolism during three important periods of in vitro development: the early development (from day 1 until day 3), the middle of culture (day 3 until day 5), and later development (day 5 until day 7).

METHODS

To obtain this information we evaluated the spent medium from each time period by ¹H NMR.

RESULTS

Our results confirm that embryo metabolism is different between sexes. The new information obtained by identifies markers that we can use to predict the embryo sex.

CONCLUSION

These results open a new, non-invasive method to evaluate sex of the embryos before the transfer. In the first period of embryo culture, valine concentration is good indicator (66.7% accurate), while in the last phase of culture, pyruvate depletion is the best marker (64% accurate) to evaluate the sex of the embryo.

[Metabolomic profiling in culture media of day-5 human embryos]

The aim of this study was to determine the changes of metabolomic profiles in embryonic culture media (ECM) for the evaluation of quality and implantation potential of human embryos. ECM (n=163) were collected on day 5 before transfer or cryopreservation. Some embryos were used in preimplantation genetic screening for detection of aneuploidy karyotypes. Samples were subdivided into groups according to embryo morphological classification (by Gardner), genetic analysis and implantation data. ECM were extracted with methanol, precipitates were separated by centrifugation and metabolite production of individual embryo was analysed by LC-MS (the positive ion mode). After peak detection and retention time alignment, data were analysed using the PCA algorithm. MS fingerprinting analysis of embryo culture medium showed significant differences between morphologically divided groups. Intragroup comparisons did not reveal differences between subclasses. Genetic screening of embryos revealed 33 aneuploid karyotypes. It was shown that chromosome number did not affect the metabolite profiles comparing with the normal group. The culture media of embryos that were positive or negative for successful implantation showed specific signatures that allowed to distinguish embryos with different outcomes.The characterization of ECMs by LC-MS may facilitate more accurate selection of the best embryo for the implantation, improving single-embryo transfer and thus eliminating the risk and undesirable effects of multiple pregnancies.

Non-invasive assessment of culture media from goat cloned embryos associated with subjective morphology by gas chromatography - mass spectroscopy-based metabolomic analysis

Pre-implantation embryo metabolism demonstrates distinctive characteristics associated with the development potential of embryos. We aim to determine if metabolic differences correlate with embryo morphology. In this study, gas chromatography - mass spectroscopy (GC-MS)-based metabolomics was used to assess the culture media of goat cloned embryos collected from high-quality (HQ) and low-quality (LQ) groups based on morphology. Expression levels of amino acid transport genes were further examined by quantitative real-time PCR. Results showed that the HQ group presented higher percentages of blastocysts compared with the LQ counterparts (P < 0.05). Metabolic differences were also present between HQ and LQ groups. The culture media of the HQ group showed lower levels of valin, lysine, glutamine, mannose and acetol, and higher levels of glucose, phytosphingosine and phosphate than those of the LQ group. Additionally, expression levels of amino acid transport genes SLC1A5 and SLC3A2 were significantly lower in the HQ group than the LQ group (P < 0.05, respectively). To our knowledge, this is the first report which uses GC-MS to detect metabolic differences in goat cloned embryo culture media. The biochemical profiles may help to select the most in vitro viable embryos.

Rapid and noninvasive technique to assess the metabolomics profile of bovine embryos produced in vitro by Raman spectroscopy

Morphological assessments are used to select embryos with the highest implantation potential, however it is still very limited. The development of new technologies, such as Raman spectroscopy have improved quantitative and qualitative analysis, and consequently led to a better characterization of embryos and improvements on the prediction of their potential. Therefore, we propose a method based on the conventional in vitro culture system of bovine embryos, and the subsequent analysis of the culture media drops by Raman spectroscopy. Our results obtained by PCA analysis clearly showed a separation of the spectral profiles from culture media drops with and without embryos.

Prediction of pregnancy viability in bovine in vitro-produced embryos and recipient plasma with Fourier transform infrared spectroscopy

We analyzed embryo culture medium (CM) and recipient blood plasma using Fourier transform infrared (FTIR) metabolomics to predict pregnancy outcome. Individually cultured, in vitro-produced (IVP) blastocysts were transferred to recipients as fresh and vitrified-warmed. Spent CM and plasma samples were evaluated using FTIR. The discrimination capability of the classifiers was assessed for accuracy, sensitivity (pregnancy), specificity (nonpregnancy), and area under the receiver operator characteristic curve (AUC). Within all IVP fresh embryos (birth rate=52%), high AUC were obtained at birth, especially with expanded blastocysts (CM: 0.80±0.053; plasma: 0.89±0.034). The AUC of vitrified IVP embryos (birth rate = 31%) were 0.607±0.038 (CM, expanded blastocysts) and 0.672±0.023 (plasma, all stages). Recipient plasma generally predicted pregnancy outcome better than did embryo CM. Embryos and recipients with improved pregnancy viability were identified, which could increase the economic benefit to the breeding industry.