Selection based on morphological assessment of oocytes and embryos at different stages of preimplantation development: a review

Ex ovo omnia-why don't we know more about egg quality via imaging?

Determining egg quality is the foremost challenge in assisted reproductive technology (ART). Although extensive advances have been made in multiple areas of ART over the last 40 years, oocyte quality assessment tools have not much evolved beyond standard morphological observation. The oocyte not only delivers half of the nuclear genetic material and all of the mitochondrial DNA to an embryo but also provides complete developmental support during embryonic growth. Oocyte mitochondrial numbers far exceed those of any somatic cell, yet little work has been done to evaluate the mitochondrial bioenergetics of an oocyte. Current standard oocyte assessment in in vitro fertilization (IVF) centers include the observation of oocytes and their surrounding cell complex (cumulus cells) via stereomicroscope or inverted microscope, which is largely primitive. Additional oocyte assessments include polar body grading and polarized light meiotic spindle imaging. However, the evidence regarding the aforementioned methods of oocyte quality assessment and IVF outcomes is contradictory and non-reproducible. High-resolution microscopy techniques have also been implemented in animal and human models with promising outcomes. The current era of oocyte imaging continues to evolve with discoveries in artificial intelligence models of oocyte morphology selection albeit at a slow rate. In this review, the past, current, and future oocyte imaging techniques will be examined with the goal of drawing attention to the gap which limits our ability to assess oocytes in real time. The implications of improved oocyte imaging techniques on patients undergoing IVF will be discussed as well as the need to develop point of care oocyte assessment testing in IVF labs.

BlastAssist: a deep learning pipeline to measure interpretable features of human embryos

STUDY QUESTION

Can the BlastAssist deep learning pipeline perform comparably to or outperform human experts and embryologists at measuring interpretable, clinically relevant features of human embryos in IVF?

SUMMARY ANSWER

The BlastAssist pipeline can measure a comprehensive set of interpretable features of human embryos and either outperform or perform comparably to embryologists and human experts in measuring these features.

WHAT IS KNOWN ALREADY

Some studies have applied deep learning and developed 'black-box' algorithms to predict embryo viability directly from microscope images and videos but these lack interpretability and generalizability. Other studies have developed deep learning networks to measure individual features of embryos but fail to conduct careful comparisons to embryologists' performance, which are fundamental to demonstrate the network's effectiveness.

STUDY DESIGN, SIZE, DURATION

We applied the BlastAssist pipeline to 67 043 973 images (32 939 embryos) recorded in the IVF lab from 2012 to 2017 in Tel Aviv Sourasky Medical Center. We first compared the pipeline measurements of individual images/embryos to manual measurements by human experts for sets of features, including: (i) fertilization status (n = 207 embryos), (ii) cell symmetry (n = 109 embryos), (iii) degree of fragmentation (n = 6664 images), and (iv) developmental timing (n = 21 036 images). We then conducted detailed comparisons between pipeline outputs and annotations made by embryologists during routine treatments for features, including: (i) fertilization status (n = 18 922 embryos), (ii) pronuclei (PN) fade time (n = 13 781 embryos), (iii) degree of fragmentation on Day 2 (n = 11 582 embryos), and (iv) time of blastulation (n = 3266 embryos). In addition, we compared the pipeline outputs to the implantation results of 723 single embryo transfer (SET) cycles, and to the live birth results of 3421 embryos transferred in 1801 cycles.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In addition to EmbryoScope™ image data, manual embryo grading and annotations, and electronic health record (EHR) data on treatment outcomes were also included. We integrated the deep learning networks we developed for individual features to construct the BlastAssist pipeline. Pearson's χ2 test was used to evaluate the statistical independence of individual features and implantation success. Bayesian statistics was used to evaluate the association of the probability of an embryo resulting in live birth to BlastAssist inputs.

MAIN RESULTS AND THE ROLE OF CHANCE

The BlastAssist pipeline integrates five deep learning networks and measures comprehensive, interpretable, and quantitative features in clinical IVF. The pipeline performs similarly or better than manual measurements. For fertilization status, the network performs with very good parameters of specificity and sensitivity (area under the receiver operating characteristics (AUROC) 0.84-0.94). For symmetry score, the pipeline performs comparably to the human expert at both 2-cell (r = 0.71 ± 0.06) and 4-cell stages (r = 0.77 ± 0.07). For degree of fragmentation, the pipeline (acc = 69.4%) slightly under-performs compared to human experts (acc = 73.8%). For developmental timing, the pipeline (acc = 90.0%) performs similarly to human experts (acc = 91.4%). There is also strong agreement between pipeline outputs and annotations made by embryologists during routine treatments. For fertilization status, the pipeline and embryologists strongly agree (acc = 79.6%), and there is strong correlation between the two measurements (r = 0.683). For degree of fragmentation, the pipeline and embryologists mostly agree (acc = 55.4%), and there is also strong correlation between the two measurements (r = 0.648). For both PN fade time (r = 0.787) and time of blastulation (r = 0.887), there's strong correlation between the pipeline and embryologists. For SET cycles, 2-cell time (P < 0.01) and 2-cell symmetry (P < 0.03) are significantly correlated with implantation success rate, while other features showed correlations with implantation success without statistical significance. In addition, 2-cell time (P < 5 × 10-11), PN fade time (P < 5 × 10-10), degree of fragmentation on Day 3 (P < 5 × 10-4), and 2-cell symmetry (P < 5 × 10-3) showed statistically significant correlation with the probability of the transferred embryo resulting in live birth.

LIMITATIONS, REASONS FOR CAUTION

We have not tested the BlastAssist pipeline on data from other clinics or other time-lapse microscopy (TLM) systems. The association study we conducted with live birth results do not take into account confounding variables, which will be necessary to construct an embryo selection algorithm. Randomized controlled trials (RCT) will be necessary to determine whether the pipeline can improve success rates in clinical IVF.

WIDER IMPLICATIONS OF THE FINDINGS

BlastAssist provides a comprehensive and holistic means of evaluating human embryos. Instead of using a black-box algorithm, BlastAssist outputs meaningful measurements of embryos that can be interpreted and corroborated by embryologists, which is crucial in clinical decision making. Furthermore, the unprecedentedly large dataset generated by BlastAssist measurements can be used as a powerful resource for further research in human embryology and IVF.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Harvard Quantitative Biology Initiative, the NSF-Simons Center for Mathematical and Statistical Analysis of Biology at Harvard (award number 1764269), the National Institute of Heath (award number R01HD104969), the Perelson Fund, and the Sagol fund for embryos and stem cells as part of the Sagol Network. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

Not applicable.

Detection of Interleukin-1 β (IL-1β) in Single Human Blastocyst-Conditioned Medium Using Ultrasensitive Bead-Based Digital Microfluidic Chip and Its Relationship with Embryonic Implantation Potential

The implantation of human embryos is a complex process involving various cytokines and receptors expressed by both endometrium and embryos. However, the role of cytokines produced by a single embryo in successful implantation is largely unknown. This study aimed to investigate the role of IL-1β expressed in a single-embryo-conditioned medium (ECM) in embryo implantation. Seventy samples of single ECM were analyzed by a specially designed magnetic-beads-based microfluidic chip from 15 women. We discovered that IL-1β level increased as the embryo developed, and the difference was significant. In addition, receiver operator characteristic (ROC) curves analysis showed a higher chance of pregnancy when the IL-1β level on day 5 ECM was below 79.37 pg/mL and the difference between day 5 and day 3 was below 24.90 pg/mL. Our study discovered a possible association between embryonic proteomic expression and successful implantation, which might facilitate single-embryo transfer in the future by helping clinicians identify the embryo with the greatest implantation potential.

The number of nuclei in compacted embryos, assessed by optical coherence microscopy, is a non-invasive and robust marker of mouse embryo quality

Optical coherence microscopy (OCM) visualizes nuclei in live, unlabeled cells. As most cells are uninucleated, the number of nuclei in embryos may serve as a proxy of the cell number, providing important information on developmental status of the embryo. Importantly, no other non-invasive method currently allows for the cell number count in compacted embryos. We addressed the question of whether OCM, by providing the number of nuclei in compacted mouse embryos, may help evaluate embryo quality. We subjected compacted embryonic Day 3 (E3.0: 72 h after onset of insemination) mouse embryos to OCM scanning and correlated nuclei number and developmental potential. Implantation was assessed using an outgrowth assay (in vitro model meant to reflect embryonic ability to implant in vivo). Embryos with more cells at E3.0 (>18 cells) were more likely to reach the blastocyst stage by E4.0 and E5.0 (P ≪ 0.001) and initiate hatching by E5.0 (P < 0.05) than those with fewer cells (<12 cells). Moreover, the number of cells at E3.0 strongly correlated with the total number of cells in E4.0 and E5.0 embryos (ρ = 0.71, P ≪ 0.001 and ρ = 0.61, P ≪ 0.001, respectively), also when only E4.0 and E5.0 blastocysts were considered (ρ = 0.58, P ≪ 0.001 and ρ = 0.56, P ≪ 0.001, respectively). Additionally, we observed a strong correlation between the number of cells at E3.0 and the number of trophectoderm cells in E4.0 and E5.0 blastocysts (ρ = 0.59, P ≪ 0.001 and ρ = 0.57, P ≪ 0.001, respectively). Importantly, embryos that had more cells at E3.0 (>18 cells) were also more likely to implant in vitro than their counterparts with fewer cells (<12 cells; P ≪ 0.001). Finally, we tested the safety of OCM imaging, demonstrating that OCM scanning affected neither the amount of reactive oxygen species nor mitochondrial activity in the embryos. OCM also did not hinder their preimplantation development, ability to implant in vitro, or to develop to term after transfer to recipient females. Our data indicate that OCM imaging provides important information on embryo quality. As the method seems to be safe for embryos, it could be a valuable addition to the current repertoire of embryo evaluation methods. However, our study was conducted only on mouse embryos, so the proposed protocol would require optimization in order to be applied in other species.

The mosaic embryo: what it means for the doctor and the patient

INTRODUCTION

Mosaic embryos are embryos that on preimplantation genetic analysis are found to be composed of euploid and aneuploid cells. Although most of these embryos do not implant when transferred into the uterus following IVF treatment, some may implant and are capable of giving rise to babies.

EVIDENCE ACQUISITION

There is currently an increasing number of reports of live births following the transfer of mosaic embryos. Compared to euploid, mosaic embryos have lower implantation rates and higher rates of miscarriage, and occasionally aneuploid component persists. However, their outcome is better than that obtained after the transfer of embryos consisting entirely of aneuploid cells. After implantation, the ability to develop into a full-term pregnancy is influenced by the amount and type of chromosomal mosaicism present in a mosaic embryo. Nowadays many experts in the reproductive field consider mosaic transfers as an option when no euploid embryos are available. Genetic counseling is an important part of educating patients about the likelihood of having a pregnancy with healthy baby but also on the risk that mosaicism could persist and result in liveborn with chromosomal abnormality. Each situation needs to be assessed on a case-by-case basis and counseled accordingly.

EVIDENCE SYNTHESIS

So far, the transfers of 2155 mosaic embryos have been documented and 440 live births resulting in healthy babies have been reported. In addition, in the literature to date, there are 6 cases in which embryonic mosaicism persisted.

CONCLUSIONS

In conclusion, the available data indicate that mosaic embryos have the potential to implant and develop into healthy babies, albeit with lower success rates than euploids. Further clinical outcomes should be collected to better establish a refined ranking of embryos to transfer.

Association of early cleavage, morula compaction and blastocysts ploidy of IVF embryos cultured in a time-lapse system and biopsied for genetic test for aneuploidy

IVF embryos have historically been evaluated by morphological characteristics. The time-lapse system (TLS) has become a promising tool, providing an uninterrupted evaluation of morphological and dynamic parameters of embryo development. Furthermore, TLS sheds light on unknown phenomena such as direct cleavage and incomplete morula compaction. We retrospectively analyzed the morphology (Gardner Score) and morphokinetics (KIDScore) of 835 blastocysts grown in a TLS incubator (Embryoscope+), which were biopsied for preimplantation genetic testing for aneuploidy (PGT-A). Only the embryos that reached the blastocyst stage were included in this study and time-lapse videos were retrospectively reanalysed. According to the pattern of initial cleavages and morula compaction, the embryos were classified as: normal (NC) or abnormal (AC) cleavage, and fully (FCM) or partially compacted (PCM) morulae. No difference was found in early cleavage types or morula compaction patterns between female age groups (< 38, 38-40 and > 40 yo). Most of NC embryos resulted in FCM (≅ 60%), while no embryos with AC resulted in FCM. Aneuploidy rate of AC-PCM group did not differ from that of NC-FCM group in women < 38 yo, but aneuploidy was significantly higher in AC-PCM compared to NC-FCM of women > 40 yo. However, the quality of embryos was lower in AC-PCM blastocysts in women of all age ranges. Morphological and morphokinetic scores declined with increasing age, in the NC-PCM and AC-PCM groups, compared to the NC-FCM. Similar aneuploidy rates among NC-FCM and AC-PCM groups support the hypothesis that PCM in anomalous-cleaved embryos can represent a potential correction mechanism, even though lower morphological/morphokinetic scores are seen on AC-PCM. Therefore, both morphological and morphokinetic assessment should consider these embryonic development phenomena.

Simultaneous transfer of one good-quality and one poor-quality cleavage stage embryo does not improve pregnancy outcomes

Embryo quality and quantity are key factors that determine the success of IVF-ET. Yet it is still unclear if, for those patients with only one good-quality embryo in an IVF cycle, the inclusion of a poor-quality embryo increases the procedure's success rate. This is a common question for both clinicians and patients in determining their course of treatment. The purpose of this work was to answer this intriguing question in the context of prognosis of patients undergoing fresh cycles with only one good-quality and more than one poor-quality cleavage-stage embryos. To control for confounding effects, we only included patients at similar age, body mass index (BMI), level of basal follicle stimulating hormone (FSH) and endometrial thickness from January 2015 to June 2021. A propensity score-matched analysis was performed to extract the matched pairs. Then we evaluated pregnancy outcome, including the rate of clinical pregnancy, live birth, embryo implantation, early miscarriage, and ectopic pregnancy. We found that the clinical pregnancy rate (34.8 vs. 38.0%, p = 0.553), live birth rate (27.1 vs. 29.9%, p = 0.598), early miscarriage rate (18.1 vs. 9.5%, p = 0.171) and ectopic pregnancy rate (1.3 vs. 1.2%, p = 1.000) did not significantly differ between those two groups, notwithstanding significant difference of the implantation rate (34.8 vs. 21.3%, p <0.001). Our work indicates that, for prognosis patients at approximately 34 years old with only one good-quality embryo, having additional poor-quality embryos does not seem to help to improve ART success rates per intended embryo transfer. In conclusion, we found that simultaneous transfer of one good-quality and one poor-quality cleavage stage embryo does not improve pregnancy outcomes.

Novel image analyser-assisted morphometric methodology offer unique opportunity for selection of embryos with potential for implantation

BACKGROUND

Previous studies looked into the connections between pregnancy and the Zona Pellucida (ZP) thickness and Zona Pellucida Thickness Variation (ZPTV), as well as the embryo's radius, circumference, perimeter and global symmetry. However, no research has linked embryo implantation and pregnancy to the percentage of ZP thinning, the reduction in ooplasm volume, and the increase in perivitelline space (PVS) volume. Our objective is to correlate the percentage of ZP thinning, the percentage of ooplasm volume shrinkage and the percentage of PVS increase to the implantation. These data will be used for embryo selection as well as it can be put into a software that will assist embryo selection.

MATERIALS AND METHODS

Retrospective study included 281 patients, all of them had 2 embryos transferred, 149 patients got pregnant with two gestation sacs and 132 patients did not get pregnant. All of the transferred embryos had the ZP thickness measured several times from time of ICSI till Embryo Transfer (ET), the ooplasm volume was calculated from time of ICSI till two Pronuclei (2PN) fading and the PVS was calculated from the ICSI time till the 2PN fading.

RESULTS

The first characteristic is the change in the average ZP thickness that decreased by 32.7% + 5.3% at 70 h for the implanted embryos (Group 1) versus 23.6% + 4.8% for non-implanted embryos (Group 2) p = 0.000. The second characteristic is the average reduction in the volume of the ooplasm which is 20.5% + 4.3% in Group 1 versus 15.1% + 5.2% in Group 2, p = 0.000. The third characteristic is the increase in the volume of the PVS which was 38.1% + 7.6% in Group 1 versus 31.6% + 9.7% in Group 2 p = 0.000.

CONCLUSION

The implanted embryos showed higher percent of ZP thinning, higher percent of ooplasm reduction and higher percent of PVS increase.

Chromatin Configuration in Diplotene Mouse and Human Oocytes during the Period of Transcriptional Activity Extinction

In the oocyte nucleus, called the germinal vesicle (GV) at the prolonged diplotene stage of the meiotic prophase, chromatin undergoes a global rearrangement, which is often accompanied by the cessation of its transcriptional activity. In many mammals, including mice and humans, chromatin condenses around a special nuclear organelle called the atypical nucleolus or formerly nucleolus-like body. Chromatin configuration is an important indicator of the quality of GV oocytes and largely predicts their ability to resume meiosis and successful embryonic development. In mice, GV oocytes are traditionally divided into the NSN (non-surrounded nucleolus) and SN (surrounded nucleolus) based on the specific chromatin configuration. The NSN-SN transition is a key event in mouse oogenesis and the main prerequisite for the normal development of the embryo. As for humans, there is no single nomenclature for the chromatin configuration at the GV stage. This often leads to discrepancies and misunderstandings, the overcoming of which should expand the scope of the application of mouse oocytes as a model for developing new methods for assessing and improving the quality of human oocytes. As a first approximation and with a certain proviso, the mouse NSN/SN classification can be used for the primary characterization of human GV oocytes. The task of this review is to analyze and discuss the existing classifications of chromatin configuration in mouse and human GV oocytes with an emphasis on transcriptional activity extinction at the end of oocyte growth.

All that glitters is not gold: a stereological study of human donor oocytes

Here we report a quantitative analysis of human metaphase II (MII) oocytes from a 22-year-old oocyte donor, retrieved after ovarian-controlled hyperstimulation. Five surplus donor oocytes were processed for transmission electron microscopy (TEM), and a stereological analysis was used to quantify the distribution of organelles, using the point-counting technique with an adequate stereological grid. Comparisons between means of the relative volumes (Vv) occupied by organelles in the three oocyte regions, cortex (C), subcortex (SC) and inner cytoplasm (IC), followed the Kruskal-Wallis test and Mann-Whitney U-test with Bonferroni correction. Life cell imaging and TEM analysis confirmed donor oocyte nuclear maturity. Results showed that the most abundant organelles were smooth endoplasmic reticulum (SER) elements (26.8%) and mitochondria (5.49%). Significant differences between oocyte regions were found for lysosomes (P = 0.003), cortical vesicles (P = 0.002) and large SER vesicles (P = 0.009). These results were quantitatively compared with previous results using prophase I (GV) and metaphase I (MI) immature oocytes. In donor MII oocytes there was a normal presence of cortical vesicles, SER tubules, SER small, medium and large vesicles, lysosomes and mitochondria. However, donor MII oocytes displayed signs of cytoplasmic immaturity, namely the presence of dictyosomes, present in GV oocytes and rare in MI oocytes, of SER very large vesicles, characteristic of GV oocytes, and the rarity of SER tubular aggregates. Results therefore indicate that the criterion of nuclear maturity used for donor oocyte selection does not always correspond to cytoplasmic maturity, which can partially explain implantation failures with the use of donor oocytes.

Non-invasive assessment of oocyte developmental competence

Oocyte quality is a key factor influencing IVF success. The oocyte and surrounding cumulus cells, known collectively as the cumulus oocyte complex (COC), communicate bi-directionally and regulate each other's metabolic function to support oocyte growth and maturation. Many studies have attempted to associate metabolic markers with oocyte quality, including metabolites in follicular fluid or 'spent medium' following maturation, gene expression of cumulus cells and measuring oxygen consumption in medium surrounding COCs. However, these methods fail to provide spatial metabolic information on the separate oocyte and cumulus cell compartments. Optical imaging of the autofluorescent cofactors - reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] and flavin adenine dinucleotide (FAD) - has been put forward as an approach to generate spatially resolved measurements of metabolism within individual cells of the COC. The optical redox ratio (FAD/[NAD(P)H+FAD]), calculated from these cofactors, can act as an indicator of overall metabolic activity in the oocyte and cumulus cell compartments. Confocal microscopy, fluorescence lifetime imaging microscopy (FLIM) and hyperspectral microscopy may be used for this purpose. This review provides an overview of current optical imaging techniques that capture the inner biochemistry within cells of the COC and discusses the potential for such imaging to assess oocyte developmental competence.

Exogenous L-Glutathione Improves Vitrification Outcomes in Murine Preimplantation Embryos

Vitrification is an important tool to store surplus embryos in assisted reproductive technology (ART). However, vitrification increases oxidative damage and results in decreased viability. Studies have reported that L-glutathione (GSH) supplementation improves the preimplantation development of murine embryos. Glutathione constitutes the major non-protein sulphydryl compound in mammalian cells, which confers protection against oxidative damage. However, the effect of GSH supplementation on embryonic vitrification outcomes has yet to be reported. This study aims to determine whether GSH supplementation in culture media improves in vitro culture and vitrification outcomes, as observed through embryo morphology and preimplantation development. Female BALB/c mice aged 6−8 weeks were superovulated through an intraperitoneal injection of 10 IU of pregnant mare serum gonadotrophin (PMSG), followed by 10 IU of human chorionic gonadotrophin (hCG) 48 h later. The mated mice were euthanized by cervical dislocation 48 h after hCG to harvest embryos. Two-cell embryos were randomly assigned to be cultured in either Group 1 (GSH-free medium), Group 2 (GSH-free medium with vitrification), Group 3 (0.01 mM GSH-supplemented medium), or Group 4 (0.01 mM GSH-supplemented medium with vitrification). Non-vitrified (Groups 1 and 3) and vitrified (Groups 2 and 4) embryos were observed for morphological quality and preimplantation development at 24, 48, 72, and 96 h. In the non-vitrified groups, there were significant increases in the number of Grade-1 blastocysts in GSH cultures (p < 0.05). Similarly, in the vitrified groups, GSH supplementation was also seen to significantly increase blastocyst formation. Exogenous GSH supplementation resulted in a significant increase in intracellular GSH, a release of cytochrome c from mitochondria, and a parallel decrease in intracellular reactive oxygen species (ROS) levels in vitrified eight-cell embryos (p < 0.05). GSH supplementation was shown to upregulate Bcl2 expression and downregulate Bax expression in the vitrified preimplantation embryo group. The action of exogenous GSH was concomitant with an increase in the relative abundance of Gpx1 and Sod1. In conclusion, our study demonstrated the novel use and practical applicability of GSH supplementation for improving embryonic cryotolerance via a decrease in ROS levels and the inhibition of apoptotic events by improvement in oxidative status.

Optical coherence microscopy allows for quality assessment of immature mouse oocytes

In brief

Optical coherence microscopy is a label-free and non-invasive imaging technique capable of 3D subcellular structure visualization. Here we show that this method allows for quality assessment of immature mouse oocytes based on their chromatin conformation and can be a valuable addition to the toolkit used in assisted reproduction procedures.

Abstract

The success of assisted reproductive technologies, and particularly in vitro maturation, is tightly linked to the quality of oocytes. Therefore, there is a need for robust, reliable, and easy-to-assess biomarkers of oocyte developmental competence. Microscopy techniques visualizing oocyte intracellular structure could provide such biomarkers. However, fluorescence imaging methods, applied frequently in biology and allowing for detailed structural and dynamic studies of single cells, require fluorescent tags to visualize cellular architecture and may cause short- and long-term photo-damage. On the other hand, traditional light microscopy, although relatively non-invasive, does not provide detailed structural information. Optical coherence microscopy (OCM) is a promising alternative, as it does not require sample pre-processing or labelling and can provide 3D images of intracellular structures. Here we applied OCM to assess the chromatin conformation of immature mouse oocytes, a feature that corresponds with their transcriptional status and developmental competence and cannot be examined by traditional light microscopy. We showed that OCM distinguished oocytes with so-called non-surrounded nucleoli (NSN) and surrounded nucleoli (SN) chromatin conformation with very high sensitivity and specificity and that OCM scanning did not decrease the quality of oocytes. Finally, we cross-referenced OCM data with the oocyte ability to undergo normal nuclear and cytoplasmic maturation and proven that indeed oocytes scored with OCM as NSN mature less effectively than oocytes scored as SN. Our results suggest that OCM may be a valuable addition to the imaging toolkit used in assisted reproduction procedures.

Association between cumulus cells—mRNA levels of AMHR2 and FSHR with oocyte maturity

Background

The gene expression of anti-Mullerian hormone receptor type 2 (AMHR2) and follicle stimulating hormone receptor (FSHR) in cumulus cells (CCs) isolated from mature and immature oocytes was studied as a possible non-invasive approach for determining oocyte maturity and quality. The CCs of 100 infertile women with different etiologic factors were subdivided into control (CCs from MII) and case (CCs from GV) group. Q-PCR was used to evaluate FSHR and AMHR2 mRNA expression levels in CCs from mature and immature oocytes.

Results

AMHR2 and FSHR genes are significantly overexpressed (4–6 fold) in CCs from immature relative to mature oocyte. The expression level of AMHR2 gene in terms of etiologic subgroups is significantly different (P value 0.000). FSHR mRNA expression levels in CCs show no significant difference regarding etiologic subgroups (P value 0.575).

Conclusion

It seems that determining the expression level of AMHR2 and FSHR genes in CCs could help to understanding molecular mechanism of oocyte maturation process.

Embryos derived from delayed mature oocyte should be cryopreserved and are favourable to transfer in a following endometrium synchronize frozen-thawed cycle

Oocytes eligible for intracytoplasmic sperm injection (ICSI) are those that have progressed through meiosis to metaphase 2 (MII). The remaining delayed mature oocytes can be injected, aiming to achieve more embryos and a better chance to conceive. We aimed to assess the outcome of delayed matured oocytes, derived from either germinal vesicles or metaphase 1 (MI), that reached maturity (MII) 24 h following retrieval. The study population consisted of 362 women who underwent 476 IVF cycles. While fertilization rates were comparable between the sibling delayed mature oocyte group compared with injection on day 0 group (58.4% vs 62%, respectively, P = 0.07), the top-quality embryo rate per injected MII day 0 oocyte was significantly higher compared with day 1 injected oocyte (57.5% vs 43.9% respectively, P < 0.001). Moreover, following fresh transfer of embryos derived from delayed mature oocytes, implantation rate and the clinical pregnancy (CPR) and live-birth rates (LBR) per transfer were 3.9%, 3.3% and 1.6% respectively. When considering the following thawed embryo transfer cycles, implantation, pregnancy and LBR were non-significantly higher (10%, 8.3% and 8.3%, respectively). Although clinical outcomes are significantly lower when using embryos derived from delayed mature oocyte to mature day 0 oocytes, the additional embryos derived from delayed mature oocytes might contribute to the embryo cohort and increase the cumulative live-birth rate per retrieval. Moreover, the embryos derived from delayed mature oocyte favour a transfer in a frozen-thawed cycle rather than in a fresh cycle.

Characterization of Uterine Peristaltic Waves by Ultrasound Strain Analysis

Uterine peristalsis (UP) is a wavelike uterine motion that plays an important role in the generation of intrauterine streams for menstrual emptying and to support embryo implantation. Our understanding of uterine mechanical behavior is hampered by a lack of quantitative analysis. Here, we propose a spatiotemporal analysis of UP by ultrasound speckle tracking and dedicated strain analysis. We aim at characterizing UP propagating around the endometrial cavity through the anterior and posterior walls of the uterus. To this end, velocity and coordination features are proposed in this study. We investigated a total of 11 healthy volunteers during their natural menstrual cycle and 81 patients undergoing in vitro fertilization (IVF) treatment. They all received multiple 4-min 2-D transvaginal ultrasound scans. Significant differences in propagation velocity were found among different phases of the menstrual cycle, which are in line with the expected uterine behavior. A significant difference in coordination was found between the group of women with successful (pregnancy at 11 weeks) and unsuccessful IVF. This result suggests that the ability to generate coordinated UP represents an important factor for IVF success. The proposed UP quantification may represent a valuable clinical tool for improved understanding of UP and improved decision-making in the context of IVF procedures.

Transcriptional profile of cumulus associated GJA1, PTX3, PRSS35, and SERPINE2 genes with oocytes and embryonic development in water buffalo

BACKGROUND

In the present study, the potential of different groups of cumulus-oocyte complexes (COC's) for in vitro maturation (IVM) and embryonic development was assessed in two groups of COC's of water buffalo. Further, the expression pattern of cumulus-associated GJA1, PTX3, PRSS35, and SERPINE2 genes and their effects on embryonic development was analyzed. Slaughterhouse-derived buffalo COC's were graded into groups A and B. An equal number of 410 COC's were taken in both groups. IVM was carried out using Slaughterhouse-derived buffalo epididymis. A remarkable degree of cumulus expansion was noticed in group A (92.68%) as compared to group B (81.25%) oocytes. On in vitro fertilization (IVF) and embryo culture, group A produced a significantly higher rate of cleavage and blastocyst (92.682 ± 0.7179% and 42.682 ± 0.9683%) as compared to group B (85.365 ± 0.7608% and 31.707 ± 0.9688%). Also, the transcriptional analysis of cumulus-associated genes revealed significantly higher expression in group A as compared to group B.

RESULTS

It was revealed that oocytes having good cumulus mass had a higher developmental potential. Based on differential gene expression of cumulus-associated genes, different quality of COC's, and the resultant embryos after IVF, it was concluded that these genes could be used as a marker for predicting the developmental competence of the oocytes.

CONCLUSION

We concluded that morphologically good quality of COC's had a higher developmental competence, and also the differential expressions of cumulus-associated genes in cumulus cells and embryos. So, we can conclude that these genes could be used as marker genes for predicting the developmental competence of buffalo's oocytes.

Oocyte quality and aging

It is well known that female reproduction ability decreases during the forth decade of life due to age-related changes in oocyte quality and quantity; although the number of women trying to conceive has today increased remarkably between the ages of 36 to 44. The causes of reproductive aging and physiological aspects of this phenomenon are still elusive. With increase in the women's age, during Assisted Reproductive Technologies (ART) we have perceived a significant decline in the number and quality of retrieved oocytes, as well as in ovarian follicle reserves. This is because of increased aneuploidy due to factors such as spindle apparatus disruption; oxidative stress and mitochondrial damage. The aim of this review paper is to study data on the potential role of the aging process impacting oocyte quality and female reproductive ability. We present the current evidence that show the decreased oocyte quality with age, related to reductions in female reproductive outcome. The aging process is complicated and it is caused by many factors that control cellular and organism life span. Although the factors responsible for reduced oocyte quality remain unknown, the present review focuses on the potential role of ovarian follicle environment, oocyte structure and its organelles. To find a way to optimize oocyte quality and ameliorate clinical outcomes for women with aging-related causes of infertility.

GDF9 concentration in embryo culture medium is linked to human embryo quality and viability

PURPOSE

We aimed to evaluate the link between the GDF9 concentration in day 3 human embryo culture medium and embryo quality and viability.

METHODS

Two independent, prospective, observational studies were conducted. In study 1, a total of 280 embryos from 70 patients who obtained at least 4 embryos with 6-10 blastomeres (2 transferable and 2 non-transferable embryos) at day 3 were enrolled. In study 2, a total of 119 embryos from 61 patients (29 fully implanted and 32 non-implanted patients) were enrolled. The corresponding GDF9 concentrations in spent culture medium of embryos were quantified by ELISA assay. The expression pattern of GDF9 in human embryos was investigated using Q-PCR and immunofluorescence.

RESULTS

GDF9 mRNA and protein were detected from human oocytes to eight-cell embryos and displayed a slow decreasing trend. In study 1, GDF9 concentration in culture medium is lower for transferable embryos compared with non-transferable embryos (331 pg/mL (quartiles: 442, 664 pg/mL) vs. 518 pg/mL (quartiles: 328, 1086 pg/mL), P < 0.001), and increased commensurate with the diminution of the embryo quality (P < 0.001). In study 2, significantly lower GDF9 concentration was detected for implanted embryos than non-implanted embryos (331 pg/mL (quartiles: 156, 665 pg/mL) vs. 518 pg/mL (quartiles: 328, 1086 pg/mL), P < 0.001). The same trend was found between the embryos that led to live birth and those that failed.

CONCLUSION

The GDF9 concentration in culture medium is linked to embryo quality and viability, and exhibited the potential to be a non-invasive biomarker for embryo selection.

Oocyte Morphometric Assessment and Gene Expression Profiling of Oocytes and Cumulus Cells as Biomarkers of Oocyte Competence in Sheep

Oocyte quality is crucial for subsequent embryo development and so it is a major challenge in assisted reproductive technologies. The aim of the present work was to evaluate the morphometric parameters of oocytes (experiment 1) and the relative gene expression of oocytes and cumulus cells (CCs) (experiment 2) as biomarkers of oocyte quality after individually culturing them (one oocyte or embryo/drop). In experiment 1, individually matured oocytes were measured and classified into small, intermediate, and large oocytes after a cluster analysis, based on total diameter (with zona pellucida, ZP), oocyte diameter (without ZP), and ZP thickness. These oocytes were individually fertilized in vitro and cultured. The embryo development was evaluated up to the blastocyst stage. According to the total diameter, oocyte diameter, and ZP thickness, the blastocyst rate decreased in the small oocytes group (3.1 ± 3.1, 14.1 ± 9.4, and 26.7 ± 3.9, respectively) compared to the intermediate (29.4 ± 5.2, 30.5 ± 10.1, and 28.6 ± 9.6, respectively) and large oocytes groups (54.2 ± 13.5, 44.4 ± 3.9, and 67.6 ± 12.4, respectively). In addition, the probability of reaching the blastocyst stage was positively related to the total diameter (p < 0.001), oocyte diameter (p < 0.05), and ZP thickness (p < 0.001). Furthermore, the relative gene expression of BAX, BCL2, GDF9, and GJA1 was lower in oocytes classified as large. In experiment 2, the mRNA transcript relative abundance pattern of genes in CCs was evaluated according to oocyte total diameter and developmental stage reached. CCs from oocytes classified as large and oocytes capable of developing to the blastocyst stage had a lower relative expression of BAX, STAR, and PTGS2, while a higher expression of HAS2 and SDC2 transcript was observed for those oocytes. In conclusion, oocyte morphometric parameters and gene expression analysis in oocytes and CCs provide methods for the identification of the most competent oocytes for assisted reproductive technologies in sheep.

Probing morphological, genetic and metabolomic changes of in vitro embryo development in a microfluidic device

Assisted reproduction technologies for clinical and research purposes rely on a brief in vitro embryo culture which, despite decades of progress, remain suboptimal in comparison to the physiological environment. One promising tool to improve this technique is the development of bespoke microfluidic chambers. Here we present and validate a new microfluidic device in polydimethylsiloxane (PDMS) for the culture of early mouse embryos. Device material and design resulted embryo compatible and elicit minimal stress. Blastocyst formation, hatching, attachment and outgrowth formation on fibronectin-coated devices were similar to traditional microdrop methods. Total blastocyst cell number and allocation to the trophectoderm and inner cell mass lineages were unaffected. The devices were designed for culture of 10-12 embryos. Development rates, mitochondrial polarization and metabolic turnover of key energy substrates glucose, pyruvate and lactate were consistent with groups of 10 embryos in microdrop controls. Increasing group size to 40 embryos per device was associated with increased variation in development rates and altered metabolism. Device culture did not perturb blastocyst gene expression but did elicit changes in embryo metabolome, which can be ascribed to substrate leaching from PDMS and warrant further investigation.

Laser Microtomography for IVF Oocyte of Human

For in vitro fertilization technology, the quality of oocytes has a direct impact on the egg fertilization and developmental competence of early embryo. The morphological criteria are used for the estimation of oocyte quality before its fertilization in vitro. To date, only one method is known to determine the maturity of oocyte. This is the routine observation with a light microscope. The aim of this article was to adapt the noninvasive quantitative laser scanning microtomography (QLSM) for the investigation of morphological features of a human oocyte in vitro. This approach was used to accumulate the Z-stack gallery of optical sections of IVF oocyte. The layer-by-layer acquisition allows the fine cytoplasmic structure imaging. Applying the QLSM Z-stack of optical sections, the cellular volume was calculated with quantitative 3D reconstruction of a human oocyte. The volume value and intracellular structure were used as novel criteria to assess the oocyte state after the stress evoked by cryopreservation procedure.

The Impact of Endometriosis on Embryo Quality in in-vitro Fertilization/Intracytoplasmic Sperm Injection: A Systematic Review and Meta-Analysis

Background: The association between endometriosis and embryological outcomes remains uncertain. The meta-analysis aimed to evaluate the impact of endometriosis on embryo quality.

Methods: A systematic review and meta-analysis was conducted to investigate the association between the endometriosis and embryo quality. Searches were performed on the three electronic databases: PubMed, EMBASE, and Web of Science. The detailed characteristics and data of the included studies were extracted. The risk ratio with 95% confidence intervals were calculated using the random and fixed effects model. The main outcome measures were high-quality embryo rate, cleavage rate, and embryo formation rate.

Results: A total of 22 studies included were analyzed. Compared with the control group, women with endometriosis had a similar high-quality embryo rate (RR = 1.00; 95% CI, 0.94–1.06), a comparable cleavage rate (RR = 1.00; 95% CI, 0.97–1.02), and a similar embryo formation rate (RR = 1.10; 95% CI, 0.97–1.24). In women with stage III-IV endometriosis, there was no statistically significantly difference in high-quality embryo rate (RR = 1.02; 95% CI, 0.94–1.10), cleavage rate (RR = 1.00; 95% CI, 0.98–1.02), and embryo formation rate (RR = 1.05; 95% CI, 0.97–1.14), compared with those without endometriosis. For women with unilateral endometrioma, pooling of results from the affected ovaries did not show a statistically significantly difference in high-quality embryo rate (RR = 0.99; 95% CI, 0.60–1.63) in comparison to the normal contralateral ovaries.

Conclusions: Our results seem to indicate that endometriosis does not compromise embryo quality from the perspective of morphology.

Noninvasive Laser Microtomography of a Human Isolated Oocyte

Using a non-invasive approach, quantitative laser scanning microtomography (QLSM), the morphology of human oocyte was studied layer-by-layer. Then, the cell volume was computed based on 3D reconstruction of a stack of optical sections obtained by QLSM. The integrity of oocyte membrane after cryopreservation was assessed by measuring the changes in oocyte volume in response to hypotonic shock.

The methylome of a human polar body reflects that of its sibling oocyte and its aberrance may indicate poor embryo development

STUDY QUESTION

Is it possible to evaluate the methylome of individual oocytes to investigate the DNA methylome alterations in metaphase II (MII) oocytes with reduced embryo developmental potential?

SUMMARY ANSWER

The DNA methylome of each human first polar body (PB1) closely mirrored that of its sibling MII oocyte; hypermethylated long interspersed nuclear element (LINE) and long terminal repeats (LTRs) and methylation aberrations in PB1 promoter regions may indicate poor embryo development.

WHAT IS KNOWN ALREADY

The developmental potential of an embryo is determined by the oocyte's developmental competence, and the PB1 is a good substitute to examine the chromosomal status of the corresponding oocyte. However, DNA methylation, a key epigenetic modification, also regulates gene expression and embryo development.

STUDY DESIGN, SIZE, DURATION

Twelve pairs of PB1s and sibling MII oocytes were biopsied and sequenced to compare their methylomes. To further investigate the methylome of PB1s and the potential epigenetic factors that may affect oocyte quality, MII oocytes (n = 74) were fertilized through ICSI, while PB1s were biopsied and profiled to measure DNA methylation. The corresponding embryos were further cultured to track their development potential. The oocytes and sperm samples used in this study were donated by healthy volunteers with signed informed consent.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Single-cell methylome sequencing was applied to obtain the DNA methylation profiles of PB1s and oocytes. The DNA methylome of PB1s was compared between the respective group of oocytes that progressed to blastocysts and the group of oocytes that failed to develop. DNA methylation levels of corresponding regions and differentially methylated regions were calculated using customized Perl and R scripts. RNA-seq data were downloaded from a previously published paper and reanalysed.

MAIN RESULTS AND THE ROLE OF CHANCE

The results from PB1-MII oocyte pair validated that PB1 contains nearly the same methylome (average Pearson correlation is 0.92) with sibling MII oocyte. LINE and LTR expression increased markedly after fertilization. Moreover, the DNA methylation levels in LINE (including LINE1 and LINE2) and LTR were significantly higher in the PB1s of embryos that could not reach the blastocyst stage (Wilcoxon-Matt-Whitney test, P < 0.05). DNA methylation in PB1 promoters correlated negatively with gene expression of MII oocyte. Regarding the methylation status of the promoter regions, 66 genes were hypermethylated in the developmental arrested group, with their related functions (significantly enriched in several Gene Ontology terms) including transcription, positive regulation of adenylate cyclase activity, mitogen-activated protein kinase (MAPK) cascade and intracellular oestrogen receptor signalling pathway.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Data analysis performed in this study focused on the competence of human oocytes and compared them with maternal genetic and epigenetic profiles. Therefore, data regarding the potential regulatory roles of paternal genomes in embryo development are lacking.

WIDER IMPLICATIONS OF THE FINDINGS

The results from PB1-oocyte pairs demonstrated that PB1s shared similar methylomes with their sibling oocytes. The selection of the good embryos for transfer should not only rely on morphology but also consider the DNA methylation of the corresponding PB1 and therefore MII oocyte. The application of early-stage analysis of PB1 offers an option for high-quality oocyte and embryo selection, which provides an additional tool for elective single embryo transfer in assisted reproduction.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Key Research and Development Program of China (2018YFC1004003, 2017YFA0103801), the National Natural Science Foundation of China (81730038, 3187144, 81521002) and the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA16020703). The authors have no conflicts of interest to declare.

Pronuclear score improves prediction of embryo implantation success in ICSI cycles

BACKGROUND

In assisted reproduction technology embryo competence is routinely evaluated on morphological criteria but efficacy remains relatively low. Additional information could be obtained by evaluating pronuclear (PN) morphology. Up to now controversial results have been reported about the prognostic value of PN score. One of the main limitations of literature data is the use of different PN classification methods. In this regard, in 2011 the ESHRE and Alpha Scientists in Reproductive Medicine defined three PN categories to standardize zygote assessment. In this study we evaluated whether the consensus ESHRE-Alpha system for the pronuclear scoring could be an useful additional criterion to improve prediction of embryo implantation potential.

METHODS

This is a retrospective, longitudinal, observational, cohort study. We included 3004 zygotes from 555 women who underwent ICSI treatment at our Center between January 2014 and June 2019. The PN were categorized as score 1: symmetrical, 2: non-symmetrical, 3: abnormal. A subset of 110 zygotes did not cleaved. On day 2-3 1163 embryos were transferred, 232 arrested, and 9 were cryopreserved. Among the 1490 embryos cultured up to day 5-7, 516 became blastocysts: 123 were transferred on day 5 and 393 were cryopreserved. Comparisons of age, cleavage and blastocyst rate, quality of embryos, implantation success among PN score groups were evaluated by chi-square test or Kruskal-Wallis test as appropriate. Potential predictors of embryo implantation were first tested in univariable analysis using generalized estimating equations taking into account correlation between embryos originated from the same patient. Then, variables potentially associated with implantation success (P<0.05) were included in a multivariable analysis for calculating the adjusted odds ratio (OR) and 95% confidence interval (CI).

RESULTS

There was no significant difference in patients'age, cleavage and blastulation rates, and embryo morphology among the three PNscore groups. The PN score 1-embryos had a greater implantation success respect to score 2-3-ones (OR 1.83; 95% CI 1.34-2.50, P=0.0001). Consistently, the pronuclear score remained predictive of implantation in top quality embryos (OR 1.68; 95%CI 1.17-2.42, P= 0.005).

CONCLUSIONS

The consensus pronuclear score may be routinely included among criteria for embryo evaluation to increase patients' chance of becoming pregnant.

The Recurrent Mutation in PATL2 Inhibits Its Degradation Thus Causing Female Infertility Characterized by Oocyte Maturation Defect Through Regulation of the Mos-MAPK Pathway

PAT1 homolog 2 (PATL2), encoding an RNA-binding protein, is a repressor involved in the translational regulation of maternal mRNAs during oocyte maturation. Previous studies have reported mutations in PATL2 those led to female infertility with oocyte maturation arrest; however, the mechanisms by which mutations affected meiotic maturation remained unclear. Here, we identified several novel and recurrent mutations of PATL2 in patients with similar phenotype, and chose the missense mutation c.649 T>A p.Tyr217Asn in PATL2 (PATL2^Y217N) as a typical to investigate the underlying mechanisms. We confirmed that this mutation disturbed oocyte maturation and observed morphological defects of large polar body, symmetrical division and abnormal spindle after microinjection of corresponding mutated mRNA. We further evaluated the effect of the PATL2^Y217N mutation in 293T cells, and found this mutation decreased the ubiquitination level and degradation of PATL2. Then, abnormally increased PATL2 bound mRNAs of Mos, an upstream activator of mitogen activated protein kinase (MAPK), to regulate its translational activity and subsequently impaired MAPK signaling pathway and oocyte meiosis. These results dissented from the previous view that PATL2 mutations reduced their expression and highlight the role of PATL2 in translational regulation of Mos and its association with MAPK signaling pathway during oocyte meiotic maturation.

Oocyte Selection for In Vitro Embryo Production in Bovine Species: Noninvasive Approaches for New Challenges of Oocyte Competence

Simple Summary

The efficiency of producing embryos using in vitro technologies in cattle species remains lower when compared to mice, indicating that the proportion of female gametes that fail to develop after in vitro manipulation is considerably large. Considering that the intrinsic quality of the oocyte is one of the main factors affecting embryo production, the precise identification of noninvasive markers that predict oocyte competence is of major interest. The aim of this review was to explore the current literature on different noninvasive markers associated with oocyte quality in the bovine model. Apart from some controversial findings, the presence of cycle-related structures in ovaries, a follicle size between 6 and 10 mm, a large slightly expanded investment without dark areas, large oocyte diameter (>120 microns), dark cytoplasm, and the presence of a round and smooth first polar body have been associated with better embryonic development. In addition, the combination of oocyte and zygote selection, spindle imaging, and the anti-Stokes Raman scattering microscopy together with studies decoding molecular cues in oocyte maturation have the potential to further optimize the identification of oocytes with better developmental competence for in vitro technologies in livestock species.

Abstract

The efficiency of producing embryos using in vitro technologies in livestock species rarely exceeds the 30–40% threshold, indicating that the proportion of oocytes that fail to develop after in vitro fertilization and culture is considerably large. Considering that the intrinsic quality of the oocyte is one of the main factors affecting blastocyst yield, the precise identification of noninvasive cellular or molecular markers that predict oocyte competence is of major interest to research and practical applications. The aim of this review was to explore the current literature on different noninvasive markers associated with oocyte quality in the bovine model. Apart from some controversial findings, the presence of cycle-related structures in ovaries, a follicle size between 6 and 10 mm, large number of surrounding cumulus cells, slightly expanded investment without dark areas, large oocyte diameter (>120 microns), dark cytoplasm, and the presence of a round and smooth first polar body have been associated with better competence. In addition, the combination of oocyte and zygote selection via brilliant cresyl blue (BCB) test, spindle imaging, and the anti-Stokes Raman scattering microscopy together with studies decoding molecular cues in oocyte maturation have the potential to further optimize the identification of oocytes with better developmental competence for in-vitro-derived technologies in livestock species.

The hare and the tortoise: extreme mitotic rates and how these affect live birth

RESEARCH QUESTION

Is live birth of patients with excessive slow (no blastocyst on day 5) and fast mitotic rate (full blastocyst development on day 4) comparable to a matched control standard (blastocyst formation on day 5)?

DESIGN

In this retrospective matched (age and anti-Müllerian hormone [AMH]) case-control study rates of fertilization, blastulation, implantation, clinical pregnancy and live birth were compared in couples with male factor indication, prolonged embryo culture and fresh single morula and blastocyst transfer.

RESULTS

The rates of implantation, clinical pregnancy and live birth in the slow-developing group were significantly (P < 0.001) lower (17.6%, 13.7%, and 11.8%, respectively) compared with the fast (58.5%, 52.5%, 47.5%) and normal growing counterparts (51.5%, 42.6%, 39.6%). No differences in neonatal outcome could be observed between the three groups. Sex ratio in the fast-growing group was not different from the other cohorts.

CONCLUSIONS

Extremely slow development, as assessed by the absence of blastulation on day 5, is a negative predictor of pregnancy and live birth. In contrast, the fear that extremely fast-growing embryos may represent an aneuploid cohort of embryos is unsubstantiated. Day-4 full blastocysts can preferentially be considered for transfer.

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.

High-quality human preimplantation embryos stimulate endometrial stromal cell migration via secretion of microRNA hsa-miR-320a

STUDY QUESTION

How do high-quality human preimplantation embryos influence the endometrium to promote their own implantation?

SUMMARY ANSWER

High-quality human preimplantation embryos secrete a specific microRNA (miRNA), hsa-miR-320a, which promotes migration of human endometrial stromal cells (hESCs).

WHAT IS KNOWN ALREADY

We have previously shown that high-quality human preimplantation embryos excrete unknown factors that influence migration of hESCs.

STUDY DESIGN, SIZE, DURATION

Embryo excreted miRNAs, specifically those excreted by high-quality embryos, were identified and their effect on hESCs was determined by measuring the migration capacity and gene expression patterns of primary isolated hESCs.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Embryo conditioned medium (ECM) from routine ICSI procedures was used to identify embryo excreted miRNAs. miRNome analyses were performed on ECM from individually cultured embryos with high morphological quality, with low morphological quality or empty control medium. MiRNA mimics and inhibitors were then used to further study the effect of miRNAs of interest on migration and gene expression of hESCs. Migration assays were performed using hESCs that were obtained from endometrial biopsies performed on hysterectomy specimens from women that received surgery for spotting due to a niche in a cesarean section scar.

MAIN RESULTS AND THE ROLE OF CHANCE

By using miRNA mimics and inhibitors, we showed that hsa-miR-320a alone can stimulate migration of decidualized hESCs, accurately resembling the response typically triggered only by high-quality embryos. Transcriptome analysis further demonstrated that this effect is very likely mediated via altered expression of genes involved in cell adhesion and cytoskeleton organization.

LIMITATIONS, REASONS FOR CAUTION

The effect of hsa-miR-320a on hESCs was measured in vitro. Further studies on the in vivo effect of hsa-miR-320a are warranted.

WIDER IMPLICATIONS OF THE FINDINGS

Implantation failure is one of the major success limiting factors in human reproduction. By secreting hsa-miR-320a, high-quality human preimplantation embryos directly influence hESCs, most likely to prime the endometrium at the implantation site for successful implantation. Together, our results indicate that hsa-miR-320a may be a promising target to further increase success rates in assisted reproduction.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Amsterdam University Medical Centers and the Amsterdam Reproduction & Development Research Institute. R.P.B., G.H. and S.M. have a patent on the use of hsa-miR-320a in assisted reproduction treatments pending.

TRIAL REGISTRATION NUMBER

N/A.

LIF in embryo culture medium is a predictive marker for clinical pregnancy following IVF-ET of patients with fallopian tube obstruction

Leukemia inhibitory factor (LIF) has played a vital role in a series of reproductive events, including follicle growth, embryo growth and differentiation. However, it is unclear whether the level of LIF in embryo culture medium can be used as a marker for clinical pregnancy. In this study, we aimed to investigate whether LIF level in embryo culture medium can act as a predictive marker for pregnancy outcome of in vitro fertilization-embryo transfer (IVF-ET) in infertile women due to tubal problems. A total of 208 infertile women due to tubal problems underwent IVF-ET treatment. The women were divided into two groups according to whether they were clinically pregnant. The level of LIF in the embryo culture medium was measured, and the correlation between LIF level and embryo quality and clinical pregnancy outcome was analyzed. The embryo culture medium was collected on the day of blastocyst transplantation. Compared to non-pregnant group, LIF level in the embryo culture medium on the day of blastocyst transplantation was significantly higher in the pregnant group. LIF level in the embryo culture medium may be used as a non-invasive auxiliary biomarker for predictive clinical pregnancy in infertile women with tubal problems that using single blastocyst transfer method.

Does Endometriosis Influence the Embryo Quality and/or Development? Insights from a Large Retrospective Matched Cohort Study

In vitro fertilization can be an effective tool to manage the endometriosis-associated infertility, which accounts for 10% of the strategy indications. Nevertheless, a negative effect of endometriosis on IVF outcomes has been suggested. The aim of this study was to evaluate the potential effect of endometriosis in the development of embryos at cleavege stage in assisted reproduction treatment cycles. A total of 429 cycles from women previously operated for moderate/severe endometriosis were compared with 851 cycles from non-affected women. Patients were matched by age, number of oocyte retrieved and study period. A total of 3818 embryos in cleavage stage have been analyzed retrospectively. Overall, no difference was found between women with and without endometriosis regarding the number of cleavage stage embryos obtained as well as the percentage of good/fair quality embryos. Excluding cycles in which no transfers were performed or where embryos were frozen in day three, no difference was observed for blastulation rate or the percentage of good/fair blastocysts obtained. Despite similar fertilization rate and number/quality of embryos, a reduction in ongoing pregnancy rate was observed in patients affected, possibly due to an altered endometrial receptivity or to the limited value of the conventional morphological evaluation of the embryo.

Live Birth Rate After Transfer of Fresh or Frozen Poor Quality Day-3 Embryos Only

Background: Embryo quality is an important predictor of successful outcome in in vitro fertilization (IVF). However, current knowledge on the live birth rate after transfer of poor quality embryos is limited. This study investigated the live birth rate after transfer of only poor quality day-3 embryos in women undergoing IVF.

Methods: This retrospective study included 153 couples who underwent IVF at IVFMD, My Duc Hospital, Ho Chi Minh City, Vietnam between June 2014 and January 2017 and had only poor quality day-3 embryos available for fresh (n [Formula: see text] 102) or frozen (n [Formula: see text] 51) transfer. The control group included patients who had transfer of one good embryo (n [Formula: see text] 64). Embryos were rated using the Istanbul criteria.

Results: In the poor quality embryo group, the mean number of oocytes retrieved and number of embryos were 7.5 ± 4.4 and 1.8 ± 0.9, respectively. Mean number of embryos transferred was 1.6 ± 0.5 in the fresh transfer group and 2.0 ± 0.2 in the freeze-only group. Live births did occur after transfer of poor quality embryos, but the implantation, clinical pregnancy and live birth rates were significantly lower than after fresh or frozen transfer of a single good quality embryo (9.5 vs. 26.6%, p < 0.001; 13.7 vs. 26.6%, p < 0.001; and 7.2 vs. 18.8%, p [Formula: see text] 0.02, respectively).

Conclusions: Live birth was achieved after transfer of only poor quality embryos in women undergoing IVF. This suggests that transfer of poor quality embryos could be an option when higher grade embryos are not available, after the chances of live birth have been discussed with the patient.

Time-lapse imaging of cytoplasmic strings at the blastocyst stage suggests their association with spontaneous blastocoel collapse

RESEARCH QUESTION

To study the origin and temporal behaviour of cytoplasmic strings spanning the blastocoel (main objective) and their influence on treatment outcome (secondary objective).

DESIGN

This retrospective analysis of prospectively collected data was set up in a university medical centre. Patients who either underwent fresh (n = 95) or vitrified-warmed (n = 55) single blastocyst transfer were included. Time-lapse sequences of in-vitro developed blastocysts were screened for the presence of cytoplasmic strings. Pregnancies in string-positive and string-negative transfers were followed up to live birth.

RESULTS

A total of 387 blastocysts were obtained in the fresh cycles of 100 patients, corresponding to a blastocyst formation rate of 62.4%. Cytoplasmic strings were first detected around full stage (108.5 ± 6.4 h) in 170 blastocysts (43.9%). The number of strings varied (range: 1-7) and the duration of visibility was 5.2 ± 3.5 h. The occurrence of cytoplasmic strings was significantly associated with the presence of blastocoelic collapses (P < 0.001) but not with any of the annotated morphokinetic parameters. Live birth and neonatal outcome were the same for both string-positive and string-negative pregnancies. Moreover, collapses did not affect treatment outcome.

CONCLUSION

Time-lapse analysis of cytoplasmic strings at the blastocyst stage revealed that this morphological feature was not a negative predictor as previously reported. Although physiologically normal, at least some of the cytoplasmic strings are an artefact, possibly associated with blastocoelic collapses.

Caffeine consumption during early pregnancy impairs oviductal embryo transport, embryonic development and uterine receptivity in mice

Caffeine consumption has been widely used as a central nervous system stimulant. Epidemiological studies, however, have suggested that maternal caffeine exposure during pregnancy is associated with increased abnormalities, including decreased fertility, delayed conception, early spontaneous abortions, and low birth weight. The mechanisms underlying the negative outcomes of caffeine consumption, particularly during early pregnancy, remain unclear. In present study, we found that pregnant mice treated with moderate (5 mg/kg) or high (30 mg/kg) dosage of caffeine (intraperitoneally or orally) during preimplantation resulted in retention of early embryos in the oviduct, defective embryonic development, and impaired embryo implantation. Transferring normal blastocysts into the uteri of caffeine-treated pseudopregnant females also showed abnormal embryo implantation, thus indicating impaired uterine receptivity by caffeine administration. The remaining embryos that managed to implant after caffeine treatment also showed increased embryo resorption rate and abnormal development at mid-term stage, and decreased weight at birth. In addition to a dose-dependent effect, significant variations between individual mice under the same caffeine dosage were also observed, suggesting different sensitivities to caffeine, similar to that observed in human populations. Collectively, our data revealed that caffeine exposure during early pregnancy impaired oviductal embryo transport, embryonic development, and uterine receptivity, which are responsible for abnormal implantation and pregnancy loss. The study raises the concern of caffeine consumption during early stages of pregnancy.

Expression of miR-Let-7a, miR-15a, miR-16-1, and their target genes in fresh and vitrified embryos and its surrounding culture media for noninvasive embryo assessment

microRNAs (miRNAs) play a critical role in implantation and development of mouse embryos. In this study, we aim to evaluate the possibility of miRNAs as potential biomarkers in the blastocyst culture to assess embryo quality. We also intend to investigate whether improved clinical outcomes of vitrified embryos agree with altered miRNA expressions. Mouse embryos from in vitro fertilization were vitrified at the two-cell stage. After thawing, the embryos were individually cultured and developed to the blastocyst stage. We used quantitative real-time polymerase chain reaction to evaluate miRNA expression levels in both vitrified and fresh groups, and culture medium (CM). The fibronectin binding assay was performed to examine for blastocyst attachment. The findings showed reduced expressions of miR-16-1 (0.2 ± 0.06) and miR-Let-7a (0.65 ± 0.1) after vitrification compared to fresh embryos. We observed significant upregulation of the target genes Vav3 (4.33 ± 0.25), integrin β-3 (Itg β3; 4.73 ± 0.2), and Bcl2 (2.29 ± 0.16) in the vitrified embryos compared to the fresh groups. Evaluation of blastocyst CM showed upregulation of miR-Let-7a (15.68 ± 0.89), miR-16-1 (16.18 ± 0.75), and miR-15a (13.36 ± 0.73) in the vitrified group in comparison to the fresh blastocysts (P < .05). The expression levels of miR-16-1 (3.28 ± 0.63), miR-15a (5.91 ± 0.38), and miR-Let-7a (9.07 ± 0.6) in CM of the vitrified blastocysts conducted on fibronectin were significantly higher than the fresh group (P < .05).This study showed that vitrification of embryos changes implantation and proliferation biomarkers. In addition, upregulated miRNAs in CM could be potentially used for noninvasive early assessment of embryo quality.

Effect of cumulus cells of cumulus-oocyte complexes on in vitro maturation, embryonic developmental and expression pattern of apoptotic genes after in vitro fertilization in water buffalo (Bubalus bubalis)

In the present study, the potential of different grades of cumulus-oocyte complexes (COCs) for in vitro maturation (IVM) and embryonic development was assessed. Further, the association of the expression pattern of anti-apoptotic Mcl-1 and pro-apoptotic Bax genes in embryonic development was analyzed. Abattoir derived oocytes were graded into grade A and B based on surrounding cumulus rings. Out of 1050 ovaries, a total number of 770 and 1360, were of grade A and B COCs, respectively, were aspirated. After IVM, grade A COCs had a significantly higher number of polar bodies (92.04 ± 0.60%) as compared to grade B (85.88 ± 0.46%). On IVF and embryo culture, grade A COCs produced the significantly higher rate of cleavage and blastocyst (90.44 ± 0.71% and 41.55 ± 0.96%) as compared to grade B COCs (79.77 ± 0.76% and 30.44 ± 0.96%). The transcriptional analysis of apoptotic genes expression by Real-time PCR revealed a significantly higher expression of Mcl-1 gene in embryos of grade A as compared to grade B, whereas, the relative expression of Bax gene was down-regulated in grade A than grade B embryos. Thus it was concluded that the pattern of apoptotic genes expression in early-stage embryos can be used as a marker gene to predict the developmental competence of COCs.

Sperm DNA fragmentation index influences assisted reproductive technology outcome: A systematic review and meta-analysis combined with a retrospective cohort study

Studies have explored the influence of DNA damage in assisted reproductive technology (ART), but the outcome remains controversial. To determine whether sperm DNA fragmentation index (DFI) has any effect on ART outcomes, we collected detailed data regarding 1,333 IVF cycles performed at our centre, and the data of our retrospective cohort study were extracted for this meta-analysis. We searched PubMed, Web of Science, EMBASE and Google Scholar and performed a systemic review and meta-analysis. Primary meta-analysis of 10 studies comprising 1,785 couples showed that live birth rate was no significantly different between low-DFI group and high-DFI group (p > 0.05). Secondary meta-analysis of 25 studies comprising 3,992 couples showed a higher miscarriage rate in high-DFI group than in low-DFI group (RR=1.57 [1.18, 2.09], p < 0.01). Meta-analysis of eight studies comprising 17,879 embryos revealed a lower good-quality embryo rate (RR=0.65 [0.62, 0.68], p < 0.01). Meta-analysis of 23 studies comprising 6,771 cycles showed that the high-DFI group had a lower clinical pregnancy rate than low-DFI group (RR=0.85 [0.75, 0.96], p < 0.01). Heterogeneity of included studies weakened our conclusions. Our study showed that DFI has adverse effects on ART outcome. More well-designed studies exploring the association between DFI and ART outcome are desired.

Single embryo transfer: Why and how to identify the embryo with the best developmental potential

Multiple pregnancies with higher risk of preterm birth and the associated higher morbidity have been a major obstacle from the early days of in vitro fertilization. A good strategy to avoid multiple pregnancies is elective single embryo transfer and cryopreservation of spare embryos. Important factors in adopting this strategy are good counselling of the patients and the selection of embryos with high implantation potential. Technical advances in embryo selection have been described during recent years, time lapse monitoring and genetic assessment of the embryos being the most important achievements. With these studies we have gained new information on early embryos. However, at present, there is insufficient evidence to recommend the routine use of these new techniques. The ultimate goal of infertility treatment is a healthy baby.

Incidence and origin of meiotic whole and segmental chromosomal aneuploidies detected by karyomapping

RESEARCH QUESTION

What is the incidence and origin of meiotic whole and segmental aneuploidies detected by karyomapping at a blastocyst stage in human-derived IVF embryos? What is the distribution of various types of errors, including rare chromosomal abnormalities?

DESIGN

The incidence of chromosomal aneuploidies was assessed in 967 trophectoderm biopsies from 180 couples who underwent 215 cycles of IVF with preimplantation genetic testing for monogenetic disease with a known causal mutation with a mean maternal age of 32.7 years. DNA from both parents and a reference sample was genotyped together with the analysed trophectoderm samples by karyomapping (single-nucleotide-polymorphism-based array).

RESULTS

Chromosomal abnormalities were detected in 31% of the analysed samples. At least one whole chromosomal aneuploidy was detected in 27.1% of the trophectoderm biopsies, whereas a segmental aneuploidy was detected in 5.1% of the trophectoderm biopsies. Our results reveal that segmental aneuploidies predominantly affect paternally derived chromosomes (70.4%; P < 0.01) compared with whole chromosomal aneuploidies that more frequently affect maternally derived chromosomes (90.1%; P < 0.0001). Also, the frequency of meiosis I (MI) and meiosis II (MII) errors was established in meiotic trisomies; MI errors were observed to be more frequent (n = 102/147 [69.4%]) than MII errors (n = 45/147 [30.6%]).

CONCLUSIONS

Karyomapping is a robust method that is suitable for preimplantation genetic testing for monogenetic disease and for detecting meiotic aneuploidies, including meiotic segmental aneuploidies, and provides complex information about their parental origin. Our results revealed that segmental aneuploidy more frequently affects paternal chromosomes compared with whole chromosomal aneuploidy in human IVF embryos at the blastocyst stage.

Is perivitelline space morphology of the oocyte associated with pregnancy outcome in intracytoplasmic sperm injection cycles?

OBJECTIVE(S)

To investigate the effect of perivitelline space (PVS) abnormalities on the outcomes of intracytoplasmic sperm injection (ICSI) cycles in which the entire cohort was affected.

STUDY DESIGN

Data from 9752 oocytes obtained from 1151 ICSI cycles performed from June/2010 to August/2016 in a private university-affiliated IVF centre. Cycles were divided into four groups according to the presence or absence of PVS abnormalities: PVS-L group (cycles with the entire oocyte cohort affected by large PVS, n = 265), PVS-G group (cycles with the entire oocyte cohort affected by PVS granularity, n = 280), PVS-L + PVS-G group (cycles with the entire oocyte cohort affected by PVS-L and PVS-G, n = 204), and control group (cycles with the entire oocyte cohort free of PVS abnormalities, n = 402). The effect of PVS abnormalities on ICSI outcomes was assessed by GLM adjusted for potential confounders.

RESULTS

Groups with PVS abnormalities presented substantially higher FSH/follicle (p < 0.001) and FSH/oocyte (p < 0.001) ratios, and lower numbers of follicles (p < 0.001), oocytes (p < 0.001) and embryos (p = 0.002) compared to the control group. PVS-L + PVS-G implantation (p = 0.044) and pregnancy (p = 0.004) rates were significantly lower than in cycles with isolated PVS abnormalities and controls.

CONCLUSION(S)

Cycles in which the entire oocyte cohort is affected by both large PVS and PVS granularity have compromised implantation and pregnancy rates.

Assessment of Prostaglandin-Endoperoxide Synthase 2 and Versican gene expression profile from the cumulus cells: association with better in vitro fertilization outcomes

BACKGROUND

Current methods for determining superior embryo quality (morphological assessment) are unable to compensate for poor pregnancy outcomes. Due to the importance of the cumulus-oocyte complex and the value of cumulus cells (CCs) as markers of embryo health, we determined the association between the CCs gene expression of the Prostaglandin-Endoperoxide Synthase 2 (PTGS2) and Versican (VCAN) with pregnancy.

METHODS

One hundred forty-nine women, suffering from infertility and undergoing IVF, were included in this study (age: 29-46 years; BMI = 25.5 ± 5.0 kg/m²). Patients underwent a standard IVF protocol. CCs were isolated during oocyte retrieval, and their RNA was isolated using Trizol. The mRNA expression of PTGS2, VCAN, and L19 was measured by qPCR. The PVL index, (PTGS2 + VCAN)*L19_normalized, was determined for each oocyte. Clinical pregnancy was confirmed by β-hCG and the presence of a fetal heartbeat. Associations were determined by ROC curves or logistic regression.

RESULTS

There was no correlation between the PVL index and morphological scores. Using only single embryo transfers (SETs), we determined that the PVL index was associated with pregnancy (β-hCG: AUC = 0.87, 95%CI: 0.74-1.00) with an optimal cutoff value of 58.2. Using the complete cohort (consisting of SETs, and patients with 2, 3, or 4 embryos transferred), the presence of at least one embryo with a PVL index score ≥ 58.2 was associated with a greater probability of achieving pregnancy (β-hCG: odds ratio = 17.15, 95%CI: 6.82-43.18, p < 0.001).

CONCLUSION

Transferring at least one embryo with a PVL index score ≥ 58.2, generates a higher chance of achieving pregnancy.

A multi-sensor system for measuring bovine embryo metabolism

This paper presents the development of a multi-sensor platform capable of simultaneous measurement of dissolved oxygen (DO) concentration, glucose and lactate concentrations in a micro-chamber for real-time evaluation of metabolic flux in bovine embryos. A micro-chamber containing all three sensors (DO, glucose, and lactate) was made to evaluate metabolic flux of single oocytes or embryos at different stages of development in ≤ 120 µL of respiration buffer. The ability of the sensor to detect a metabolic shift from oxidative phosphorylation (OXPHOS) to glycolysis was demonstrated in embryos by an ablation of oxygen consumption and an increase in lactate production following addition of oligomycin, an inhibitor of mitochondrial adenosine triphosphate (ATP) synthesis. An increased reliance upon glycolysis relative to OXPHOS was demonstrated in embryos as they developed from morula to hatched blastocysts by a progressive increase in the lactate/oxygen flux ratio, consistent with isolated metabolic assessments reported previously. These studies highlight the utility of a metabolic multi-sensor for integrative real-time monitoring of aerobic and anaerobic energy metabolism in bovine embryos, with potential applications in the study of metabolic processes in oocyte and early embryonic development.

Next Generation Sequencing (NGS) in chromosome translocation 46, XX, t (9; X) (q22; q28) - a case report

This paper reports the case of a patient who sought assisted reproductive technology (ART) treatment and was referred to pre-implantation genetic diagnosis (PGD) on account of a chromosomal translocation presented with secondary infertility. The patient underwent a highly complex ART treatment and had 14 metaphase II oocytes collected on the day of follicular aspiration. The embryos were taken to extended culture and five were biopsied and vitrified. The embryo genetic report showed aneuploidy in four of the blastocysts, while the other resulted in 46, XX. In conclusion, chromosome translocations involving the X chromosome might result in the deregulation of gene expression and defective ovarian formation. Therefore, the genes present in the X chromosome are believed to be essential in normal ovarian function.

Making IVF more effective through the evolution of prediction models: is prognosis the missing piece of the puzzle?

Assisted reproductive technology has evolved tremendously since the emergence of in vitro fertilization (IVF). In the course of the recent decade, there have been significant efforts in order to minimize multiple gestations, while improving percentages of singleton pregnancies and offering individualized services in IVF, in line with the trend of personalized medicine. Patients as well as clinicians and the entire IVF team benefit majorly from 'knowing what to expect' from an IVF cycle. Hereby, the question that has emerged is to what extent prognosis could facilitate toward the achievement of the above goal. In the current review, we present prediction models based on patients' characteristics and IVF data, as well as models based on embryo morphology and biomarkers during culture shaping a complication free and cost-effective personalized treatment. The starting point for the implementation of prediction models was initiated by the aspiration of moving toward optimal practice. Thus, prediction models could serve as useful tools that could safely set the expectations involved during this journey guiding and making IVF treatment more effective. The aim and scope of this review is to thoroughly present the evolution and contribution of prediction models toward an efficient IVF treatment.

ABBREVIATIONS

IVF: In vitro fertilization; ART: assisted reproduction techniques; BMI: body mass index; OHSS: ovarian hyperstimulation syndrome; eSET: elective single embryo transfer; ESHRE: European Society of Human Reproduction and Embryology; mtDNA: mitochondrial DNA; nDNA: nuclear DNA; ICSI: intracytoplasmic sperm injection; MBR: multiple birth rates; LBR: live birth rates; SART: Society for Assisted Reproductive Technology Clinic Outcome Reporting System; AFC: antral follicle count; GnRH: gonadotrophin releasing hormone; FSH: follicle stimulating hormone; LH: luteinizing hormone; AMH: anti-Müllerian hormone; DHEA: dehydroepiandrosterone; PCOS: polycystic ovarian syndrome; NPCOS: non-polycystic ovarian syndrome; CE: cost-effectiveness; CC: clomiphene citrate; ORT: ovarian reserve test; EU: embryo-uterus; DET: double embryo transfer; CES: Cumulative Embryo Score; GES: Graduated Embryo Score; CSS: Combined Scoring System; MSEQ: Mean Score of Embryo Quality; IMC: integrated morphology cleavage; EFNB2: ephrin-B2; CAMK1D: calcium/calmodulin-dependent protein kinase 1D; GSTA4: glutathione S-transferase alpha 4; GSR: glutathione reductase; PGR: progesterone receptor; AMHR2: anti-Müllerian hormone receptor 2; LIF: leukemia inhibitory factor; sHLA-G: soluble human leukocyte antigen G.

Can trophectoderm morphology act as a predictor for euploidy?

Objective

Euploid embryo transfers yield better implantation rates. In Brazil, morphological evaluation is performed to select the best embryos, since genetic analysis is still an expensive procedure. This study aimed to evaluate whether there is an association between trophectoderm morphology and ploidy status.

Methods

The study included 113 blastocysts formed in D5/D6 from 58 in vitro fertilization cycles held from January/2016 to May/2017. All patients with indication for PGD/PGS were included in the study. The mean age of the female patients was 37.04±5.65years. Biopsied blastocysts were categorized for morphology. Cells were sent for genetic analysis using the CGH array, SNP array or NGS techniques. Statistical analysis was performed using the chi square test, and statistical significance was assigned to differences with p≤0.05.

Results

Chromosome analysis revealed that 44 (38.9%) blastocysts were euploid. Blastocysts with trophectoderm grades A, B, and C had euploidy rates of 71.43%, 60% and 19.67%, respectively (p≤0.05).

Conclusion

Although the best trophectoderm morphology grades had higher euploidy rates, this indicator alone is not enough to warrant embryo genetic viability.

Clinical analysis of the patients with single fair cleavage-stage embryo on day 3

OBJECTIVE

This study aimed to explore an appropriate selection for the patients with single fair cleavage-stage embryo on day 3.

METHODS

This study included 469 fresh transfers and 220 frozen-thawed transfers from January 2014 to June 2016. Furthermore, in 72 patients who have only 4-6 fair embryos (4-5 blastomeres) on day 3, the blastocysts were cultured to day 5 for transfer.

RESULTS

In the fresh transfers, the clinical pregnancy rate of 4-5 blastomeres group was significantly lower than 6-7 and 8-10 blastomeres group (5.88 vs. 30.13%, p<.001and 5.88 vs. 26.09%, p < .001). In the frozen-thawed transfers, the clinical pregnancy rate of 4-5 blastomeres group was also significantly lower than 6-7 and 8-10 blastomeres group (10.00 vs. 28.57%, p = .040 and 10.00 vs. 33.33%, p = .005). For the blastocyst transfers derived from fair embryos with 4-5 blastomeres, the clinical pregnancy rate was significantly higher than single and double fair embryo transfers of similar quality (44.44 vs. 7.04%, p < .001 and 44.44 vs. 28.09%, p = .013).

CONCLUSIONS

For the patients with single fair embryo (6-7 blastomeres or 8-10 blastomeres), transfer at the cleavage stage is feasible. For the patients with single fair embryo (4-5 blastomeres), transfer of single fair embryo at the blastocyst stage or accumulating two fair embryos might be worthy of consideration.