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

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.

Homocysteine serum levels correlate with the number of failed IVF cycles even when within normal range

INTRODUCTION

Repeated implantation failure is a common challenge in daily practice. Homocysteine and vitamin B12 have been associated with reproductive processes among patients undergoing in vitro fertilization; however, their involvement in repeated implantation failure has not been assessed. We explored possible associations of serum homocysteine and vitamin B12 with repeated implantation failure.

MATERIAL AND METHODS

A retrospective analysis of 127 women who underwent ≥ 3 unsuccessful embryo transfers during 2005-2016, at the Fertility and In Vitro Fertilization Unit at Carmel Medical Center. After at least 3 IVF failures serum levels of homocysteine and vitamin B12 were measured.

RESULTS

The mean patient age was 33.5 ± 5.2 years. The mean number of embryo transfers was 4.6 ± 1.5. The mean total cumulative number of embryos transferred was 10.4 ± 5.2. Mean serum levels of homocysteine were 8.6 ± 3.7 µM/L, and of vitamin B12 were 302.5 ± 155.3 pg/ml. Homocysteine levels were within the normal range (< 14 µM/L) in 95.8% of the patients. Yet, the levels of homocysteine correlated with both the number of failed embryo transfers (r = 0.34, p = 0.004) and the total cumulative number of transferred embryos (r = 0.36, p = 0.002).

CONCLUSIONS

Our findings suggest an association between serum homocysteine levels and the occurrence of repeated implantation failure, even when homocystein levels were within the normal range. It should be studied whether nutritional supplementation to modulate serum homocysteine levels may improve treatment outcome.

OXIDATIVE STRESS AND REPRODUCTIVE FUNCTION: Reactive oxygen species in the mammalian pre-implantation embryo

In brief

Reactive oxygen species are generated throughout the pre-implantation period and are necessary for normal embryo formation. However, at pathological levels, they result in reduced embryo viability which can be mediated through factors delivered by sperm and eggs at conception or from the external environment.

Abstract

Reactive oxygen species (ROS) occur naturally in pre-implantation embryos as a by-product of ATP generation through oxidative phosphorylation and enzymes such as NADPH oxidase and xanthine oxidase. Biological concentrations of ROS are required for crucial embryonic events such as pronuclear formation, first cleavage and cell proliferation. However, high concentrations of ROS are detrimental to embryo development, resulting in embryo arrest, increased DNA damage and modification of gene expression leading to aberrant fetal growth and health. In vivo embryos are protected against oxidative stress by oxygen scavengers present in follicular and oviductal fluids, while in vitro, embryos rely on their own antioxidant defence mechanisms to protect against oxidative damage, including superoxide dismutase, catalase, glutathione and glutamylcysteine synthestase. Pre-implantation embryonic ROS originate from eggs, sperm and embryos themselves or from the external environment (i.e. in vitro culture system, obesity and ageing). This review examines the biological and pathological roles of ROS in the pre-implantation embryo, maternal and paternal origins of embryonic ROS, and from a clinical perspective, we comment on the growing interest in combating increased oxidative damage in the pre-implantation embryo through the addition of antioxidants.

Should Intra Cytoplasmic Sperm Injection (ICSI) be the primary insemination method in women undergoing IVF cycles with donor sperm?

PURPOSE

To compare efficacy of Intra Cytoplasmic Sperm Injection (ICSI) with conventional in vitro fertilization (IVF) on treatment outcome in women undergoing in vitro fertilization with donor sperm.

METHODS

We examined retrospectively the outcome data from 203 patients undergoing fresh cycles of conventional IVF (cIVF) or ICSI and an additional 77 frozen-thawed embryo transfer (FET) cycles during 2003-2014, all using donor sperm. Fertilization, cleavage, pregnancy and live birth rates and number of high-quality embryos were compared between cIVF and ICSI.

RESULTS

Altogether 185 women underwent 479 transfer cycles of fresh embryos (237 cIVF vs. 224 ICSI and 18 "rescue ICSI" cycles). In addition, 77 FET cycles were compared (24 cIVF vs. 53 ICSI cycles). No differences were found between cIVF and ICSI in fertilization, cleavage, pregnancy and live birth rates (92.6% vs 92.2%, 73.4% vs 72.4%, 25.3% vs 27.2% and 13.1% vs 14.7%, respectively). Pregnancy and life birth rates remained similar even when FET cycles were included (25.8% vs 26.2% and 13.1% vs 13.7%, respectively). The use of ICSI was associated with lower rates of high-quality embryos (52.7% vs. 63.3%, P < 0.0001). A multivariate logistic regression analysis found that patients' age, number of transferred embryos and smoking were independently associated with the chance to conceive. Patient age correlated inversely with fertilization rate (r = - 0.13, P < 0.006).Non-smokers were more likely to become pregnant (OR = 2.23, P < 0.012).

CONCLUSIONS

Our results show that ICSI does not bypass the age-related decrease in oocyte quality in patients using donor sperm for IVF. Use of ICSI was associated with lower rates of high-quality embryos. The findings imply that ICSI should not be the primary method of insemination in patients undergoing IVF with donor sperm.

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.

Novel noninvasive embryo selection algorithm combining time-lapse morphokinetics and oxidative status of the spent embryo culture medium

OBJECTIVE

To develop a noninvasive embryo selection algorithm consisting of time-lapse morphokinetics and the oxidative status of the spent embryo culture medium determined using the Thermochemiluminescence (TCL) Analyzer.

DESIGN

Retrospective cohort.

SETTING

Not applicable.

PATIENT(S)

From women participating in the oocyte donation program, data from 505 samples of spent embryo culture media samples from 292 intracytoplasmic sperm injection cycles.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Morphokinetic parameters assessed during incubation in the time-lapse system Embryoscope. Oxidative parameters (H1_sm, H2_sm, and H3_sm) from the spent culture medium on day 5 of incubation measured using the TCL assay; and a combined assessment algorithm, including morphology, morphokinetics, and the embryo's culture medium oxidative status, developed as a tool for embryo selection, based on implantation success and confirmed ongoing pregnancy.

RESULT(S)

The levels of the oxidative parameters H1_sm, H2_sm, and H3_sm on day 5 of incubation were statistically significantly higher in transferred and vitrified embryos compared with discarded embryos and in successfully implanted embryos compared with those that did not result in pregnancy. The assessment algorithm resulted in a hierarchical classification with six embryo quality categories (A to F), associated with implantation rates of between 76.5% and 29.2%.

CONCLUSION(S)

An assessment algorithm combining morphology, morphokinetics and the embryo's culture medium oxidative status may help to improve current embryo selection methods criteria and in vitro fertilization success.

Oxidative markers in cryopreservation medium from frozen-thawed embryos: a possible tool for improved embryo selection in in vitro fertilization?

PURPOSE

The present study evaluated the association between oxidative parameters in embryo cryopreservation medium and laboratory and clinical outcomes.

METHODS

This prospective laboratory study was conducted in an IVF unit in a university-affiliated hospital with 91 IVF patients undergoing a frozen-thawed embryo transfer cycle. Following thawing, 50 μL of embryo cryopreservation medium was retrieved from each cryotube and tested by the thermochemiluminescence (TCL) assay. TCL amplitudes after 50 (H1), 150 (H2), and 280 s (H3) were recorded in counts per second (CPS) and the TCL ratio determined for comparison with implantation and pregnancy rates.

RESULTS

A total of 194 embryos were transferred in 85 frozen-thaw cycles. Twenty-one pregnancies (24.7 %) occurred. Implantation and overall and clinical pregnancy rates were higher when the median TCL H1 amplitude was <32 CPS compared to ≥32 CPS (14.6 vs. 5.3 %, 37.5 vs. 17 %, 28.1 vs. 9.4 %, respectively). No pregnancies occurred when the H1 amplitude was ≥40 CPS. Logistic regression multivariate analysis found that only the median TCL H1 amplitude was associated with the occurrence of pregnancy (OR = 2.93, 95 % CI 1.065-8.08). The TCL ratio inversely correlated with the duration of embryo cryopreservation (r = -0.37).

CONCLUSIONS

The results indicate that thawed embryos may express oxidative processes in the cryopreservation medium, and higher oxidative levels are associated with lower implantation rates. These findings may aid in the improved selection of frozen-thawed embryos for IVF.

Noninvasive metabolomic profiling of human embryo culture media using a simple spectroscopy adjunct to morphology for embryo assessment in in vitro fertilization (IVF)

Embryo quality is crucial to the outcome of in vitro fertilization (IVF); however, the ability to precisely distinguish the embryos with higher reproductive potential from others is poor. Morphologic evaluation used to play an important role in assessing embryo quality, but it is somewhat subjective. The culture medium is the immediate environment of the embryos in vitro, and a change of the substances in the culture medium is possibly related to the embryo quality. Thus, the present study aims to determine whether metabolomic profiling of the culture medium using Raman spectroscopy adjunct to morphology correlates with the reproductive potential of embryos in IVF and, thus, to look for a new method of assessing embryo quality. Fifty seven spent media samples were detected by Raman spectroscopy. Combined with embryo morphology scores, we found that embryos in culture media with less than 0.012 of sodium pyruvate and more than −0.00085 phenylalanine have a high reproductive potential, with up to 85.7% accuracy compared with clinical pregnancy. So, sodium pyruvate and phenylalanine in culture medium play an important role in the development of the embryo. Raman spectroscopy is an important tool that provides a new and accurate assessment of higher quality embryos.

Release of superoxide dismutase-1 by day 3 embryos of varying quality and implantation potential

PURPOSE

To determine if the antioxidant superoxide dismutase-1 (SOD1 or Cu,Zn-SOD) is released by cultured human cleavage-stage embryos and to assess any link between SOD1 and implantation potential.

METHODS

Women (n = 91; ≤40 years old) undergoing IVF treatment with transfer of one or two 8-cell embryos that resulted in 0 or 100% implantation were included. Following individual embryo culture, spent medium samples (n = 122) were collected and levels of SOD1 protein were measured by an enzyme-linked immunosorbent assay. SOD1 detection and concentration in embryo spent medium were analyzed in relation to embryo fragmentation and symmetry scores, and implantation (viable fetus at >12 weeks).

RESULTS

Cleavage-stage embryos release SOD1 protein into the spent culture medium. Neither detection nor concentration of SOD1 was related to implantation. There was a positive relationship between increased embryo fragmentation scores and SOD1 release, with no apparent association with symmetry. In non-pregnant cycles, the release of SOD1 decreased with increasing maternal age.

CONCLUSIONS

While SOD1 does not predict implantation potential of select good-quality embryos, our data support the need to evaluate the biological significance of released SOD1 by embryos of varying quality and from patients of varying age.