Embryological strategies for overcoming recurrent assisted reproductive technology treatment failure

Placental trophoblast cell-derived exosomal microRNA-1290 promotes the interaction between endometrium and embryo by targeting LHX6

Communication between the maternal uterus and the embryo is vital for a successful pregnancy. Exosomes, subtypes of extracellular vesicles comprising many bioactive factors, regulate the early stages of pregnancy, specifically during embryo implantation. Nevertheless, the mechanism by which exosomal microRNAs (miRNAs) derived from placental trophoblasts regulate embryo implantation remains elusive. We isolated and identified exosomes derived from placental trophoblast cells (HTR8/SVneo). Subsequently, we evaluated the loading miRNA in exosomes by small RNA sequencing. Consequently, we showed that trophoblast cell-derived exosomes could transfer to endometrial epithelial cells. Besides, these exosomes promoted the epithelial-mesenchymal transition (EMT) as well as migration of endometrial cells and were implicated in the regulation of inflammation. Further, the specific miRNAs were screened in exosomes, and as a result, miRNA (miR)-1290 was enriched specifically in exosomes. miR-1290 promoted the expression of inflammatory factors (interleukin [IL]-6 and IL-8) and migration of endometrial epithelial cells. In addition, exosomal miR-1290 promoted angiogenesis in vitro. More importantly, by targeting LHX6, trophoblast HTR8/SVneo cell-derived exosomal miR-1290 promoted the EMT process of endometrial epithelial cell HEC-1-A. Altogether, our findings provide novel insights into the mechanism of trophoblast cell-derived exosomes during embryo implantation.

Microvesicles provide a mechanism for intercellular communication by embryonic stem cells during embryo implantation

Communication between the inner cell mass (ICM) and the trophoblast layer of the blastocyst is known to occur, but its functional consequences on early developmental events is unclear. Here we demonstrate that embryonic stem (ES) cells derived from the ICM generate and shed microvesicles (MVs), a major class of extracellular vesicles (EVs), which influence trophoblast behaviour during the implantation process. The MV cargo proteins laminin and fibronectin interact with integrins along the surfaces of the trophoblasts, triggering the activation of two signalling kinases, JNK and FAK, and stimulating trophoblast migration. We further show that injecting MVs isolated from ES cells into blastocysts results in an increase in their implantation efficiency. Thus, these findings highlight a unique mechanism by which ES cells communicate with trophoblasts within the blastocyst to increase their ability to migrate into the uterus, thereby promoting one of the earliest and most important steps during pregnancy.

It is unclear how embryonic stem cells (ESC) communicate with surrounding cells during implantation. Here, the authors show that microvesicles (MV) are shed from ESCs, activating integrin and JNK/FAK kinases in trophoblasts, stimulating migration in vitro, and injecting MVs enhances blastocyst implantation.

Diminished ovarian reserve in the United States assisted reproductive technology population: diagnostic trends among 181,536 cycles from the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System

OBJECTIVE

To evaluate trends in diminished ovarian reserve (DOR) assignment in the Society for Assisted Reproductive Technology (SART) Clinic Outcomes Reporting System database and to evaluate its accuracy in predicting poor ovarian response (POR) as defined in European Society of Human Reproduction and Embryology's Bologna criteria (2011).

DESIGN

Retrospective cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 181,536 fresh, autologous ART cycles reported to SART by U.S. clinics in 2004 and 2011 (earliest and most recent available reporting years).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

DOR assignment was the primary exposure. POR, defined as cycle cancellation for poor response or less than 4 oocytes retrieved after conventional gonadotropin stimulation (>149 IU FSH daily), was the primary outcome. Secondary outcomes were live birth and number of oocytes retrieved. DOR prevalence, power of DOR and FSH (</≥12 mIU/mL) to predict POR, and live birth in POR cycles were also calculated.

RESULT(S)

DOR prevalence increased from 19% to 26% from 2004 to 2011. Among cycles clinically assigned as DOR, incidence of POR decreased from 32% to 30%, and live birth improved from 15% to 17%. Comparing basal FSH ≥12 versus clinical assignment of DOR, basal FSH had a higher specificity (92.2% vs. 81.6%) and positive predictive value (38.3% vs. 30.9%) for predicting POR. Live birth among POR cycles was 4%.

CONCLUSION(S)

DOR diagnosis is increasing, and accuracy remains poor, despite the availability of additional diagnostic parameters such as antral follicle count and antimüllerian hormone. POR entailed poor outcomes, but the majority of patients clinically assigned as DOR did not experience POR. Development and use of more accurate predictors of POR are needed to minimize patient distress resulting from overdiagnosis.

A minimally invasive methodology based on morphometric parameters for day 2 embryo quality assessment

The risk of multiple pregnancy to maternal-fetal health can be minimized by reducing the number of embryos transferred. New tools for selecting embryos with the highest implantation potential should be developed. The aim of this study was to evaluate the ability of morphological and morphometric variables to predict implantation by analysing images of embryos. This was a retrospective study of 135 embryo photographs from 112 IVF-ICSI cycles carried out between January and March 2011. The embryos were photographed immediately before transfer using Cronus 3 software. Their images were analysed using the public program ImageJ. Significant effects (P < 0.05), and higher discriminant power to predict implantation were observed for the morphometric embryo variables compared with morphological ones. The features for successfully implanted embryos were as follows: four cells on day 2 of development; all blastomeres with circular shape (roundness factor greater than 0.9), an average zona pellucida thickness of 13 µm and an average of 17695.1 µm² for the embryo area. Embryo size, which is described by its area and the average roundness factor for each cell, provides two objective variables to consider when predicting implantation. This approach should be further investigated for its potential ability to improve embryo scoring.

Embryo culture and selection: morphological criteria

In this chapter, we have outlined the various morphological criteria for selection of the best embryo at each important milestone encountered in the progress from the oocyte to the blastocyst. As Gerris et al. stated, a combination of one, two, or even three selection points should lead to a more accurate selection of the best embryo, as no one criterion is better than the other. An embryo that fails to meet the entire set of selection criteria must be avoided as culture cannot correct an impaired embryo.

Is pronuclear scoring a really good predictor for ICSI cycles?

BACKGROUND/AIMS

Since the assessments of the morphology of oocytes, zygotes and/or embryos are of crucial importance to select the best candidate for pregnancy, many morphological evaluation tools have been proposed. Although embryo scoring, particularly cleavage and blastocyst stages, is more convincing due to successful results, zygote scoring still have a bias as different outcomes. In the current study, we designed a prospective study to test the reliability of zygote scoring by focusing on zygote evaluation techniques and its relation with embryo development and embryo selection for transfer.

METHODS

A total of 1215 mature oocytes from 139 couples were evaluated for the study.

RESULTS

There is no correlation between published zygote scoring technique and embryo development.

CONCLUSIONS

We conclude that the inconsistency of data obtained from zygote scoring might be caused by the static nature of pronuclear stage embryos and thus pronuclear scoring seems to be unreliable evaluation technique for embryo selection.

Rhythmic actomyosin-driven contractions induced by sperm entry predict mammalian embryo viability

Fertilization-induced cytoplasmic flows are a conserved feature of eggs in many species. However, until now the importance of cytoplasmic flows for the development of mammalian embryos has been unknown. Here, by combining a rapid imaging of the freshly fertilized mouse egg with advanced image analysis based on particle image velocimetry, we show that fertilization induces rhythmical cytoplasmic movements that coincide with pulsations of the protrusion forming above the sperm head. We find that these movements are caused by contractions of the actomyosin cytoskeleton triggered by Ca²⁺ oscillations induced by fertilization. Most importantly, the relationship between the movements and the events of egg activation makes it possible to use the movements alone to predict developmental potential of the zygote. In conclusion, this method offers, thus far, the earliest and fastest, non-invasive way to predict the viability of eggs fertilized in vitro and therefore can potentially improve greatly the prospects for IVF treatment.

Cytoplasmic flows—the movement of cytoplasmic material—can be detected following the fertilization of an egg by a sperm in many species. In this study, rhythmic cytoplasmic flows are shown to be induced in mice by calcium-induced cytoskeleton contractions which could be used to predict the successful outcome of fertilization.

Improvement of pregnancy rate by modification of embryo transfer technique: a randomized clinical trial

In this randomized trial study, two groups of infertile women (n=55) aged≤40 years underwent in vitro fertilization or intracytoplasmic sperm injection treatment cycles with or without 0.2 mL of air pushed into the catheter after embryo transfer. The implantation and clinical pregnancy rates were statistically significantly higher in the study group than in the controls. This improvement on standard ET technique may advance clinical pregnancy rates.

Morphologic parameters of early cleavage-stage embryos that correlate with fetal development and delivery: prospective and applied data for increased pregnancy rates

BACKGROUND

Many different embryo selection criteria have been used in assisted reproductive technologies (ART), but there are no published prospective studies to ascertain their usefulness in predicting implantation.

METHODS

In a prospective trial, 20 early scoring parameters previously reported to influence clinical outcome were collected, but embryos were selected for transfer by current laboratory protocols; day 1 pronuclear (PN) (Z) score combined with day 3 or 5 morphology. Data points for each oocyte/embryo were scored independently and tracked individually. Data were analysed retrospectively for parameters most likely to result in a positive pregnancy test, fetal heartbeat (FHB) and delivery.

RESULTS

Results indicated that day 1 PN morphology and nucleolar precursor body (NPB) ratio, day 2 cell number, blastomere symmetry and nucleation and the ability to cleave from day 2 to day 3 were the six most significant factors in fetal development. This outcome was then applied prospectively over 8 months. The implantation rate (IR) and clinical pregnancy rate (CPR) increased in each age group, and the number of embryos used decreased.

CONCLUSION

In conclusion, early parameters that include PN morphology, number and ratio of NPBs per nucleus and the day 2 morphology of cleaving embryos are stronger positive predictors of implantation than day 3 morphology or the ability to achieve the blastocyst stage of development. Parameters that were most consistently correlated with no delivery were lack of PN symmetry, day 2 multinucleation and uneven cell size. Day 3 and day 5 parameters were not significant compared with the combination of early parameters.

The limited importance of pronuclear scoring of human zygotes

BACKGROUND

Several studies have shown a correlation between the pronuclear morphology score (PNMS) and subsequent embryo development and implantation. Embryos with poor pronuclear score, elsewhere referred to as Z3 and Z4, are often not transferred or cryopreserved because it is believed that they have poor pregnancy potential. The objective of this study is to report our data on the use of the pronuclear score and its effect on pregnancy outcome.

METHODS

Retrospective analysis of IVF/ICSI-embryo transfer cycles completed over the course of 1 year (n = 334). Comparisons were made only in those groups of patients in whom cohorts of similarly scored PNMS embryos were transferred. The proportion of such homologous cohorts was 104/334 (31%). All other replacements were excluded from final analysis as they were dissimilar as far as PNMS is concerned. Pregnancy outcomes were evaluated.

RESULTS

The incidence of live birth resulting from the transfer of single pronuclear score homologous embryo types was 56 (14/25), 41 (13/32), 54 (23/43) and 0% (0/4) for PNMS scores 1, 2, 3 and 4, respectively. There was no correlation between PNMS category of the embryos transferred and live birth rates (P = 0.139).

CONCLUSIONS

PNMSs of 1, 2 or 3 do not correlate with live birth rates when assessing unique PNMS embryo transfers. In particular, previously considered poor (type 3) embryos can result in pregnancy with normal live birth rates. Whether type 4 embryos are compatible with normal development remains to be shown.

Relationship between pre-embryo pronuclear morphology (zygote score) and standard day 2 or 3 embryo morphology with regard to assisted reproductive technique outcomes

OBJECTIVE

To test the hypothesis that pregnancy rates are low if grade Z1 pre-embryos are not available for transfer and to determine if pronuclear morphology is a better predictor of pregnancy than traditional embryo morphology.

DESIGN

Prospective clinical study.

SETTING

Academic human reproduction laboratory.

PATIENT(S)

One hundred couples undergoing IVF with conventional insemination or ICSI.

INTERVENTION(S)

Embryo quality was assessed using both pre-embryo pronuclear morphology (zygote scoring or Z-scoring) at the time of fertilization evaluation and standard day 2 and day 3 embryo morphology (number of blastomeres and grading based on degree of fragmentation and blastomere size).

MAIN OUTCOME MEASURE(S)

We tested two decision models, one based on Z-scores and another on morphology, to determine which grading system better predicted pregnancy outcomes in assisted reproductive technique. Zygote score and embryo morphology were measured for all embryos and the transferred embryo pool. Implantation and pregnancy rates resulting from the embryo transfers of all cycles were calculated.

RESULT(S)

The Z-score distribution of 552 embryos was 27% Z1, 8% Z2, 50% Z3, and 15% Z4. Z1 and Z3 embryos had significantly (P approximately .03) higher quality over Z2 and Z4 embryos. Using the Z-score decision model with Z1 embryos having highest priority for transfer, pregnancy rates were similar between Z1 and Z3 embryos. Using embryo morphology as a decision model, pregnancy rates were highest in transfers containing one or two "best"-quality embryos.

CONCLUSION(S)

Z1 and Z3 embryos had similar morphology and pregnancy rates. The decision model based on the Z-score model was not better than standard embryo morphology in predicting pregnancy outcome.

Investigation and current management of recurrent IVF treatment failure in the UK

OBJECTIVE

To determine current practice in the management of recurrent in vitro fertilisation (IVF) treatment failure in licensed UK infertility centres.

DESIGN

National postal questionnaire study and literature review.

SETTING

University Hospital, Centre for Reproductive Medicine, Coventry, UK.

SAMPLE

Human Fertilisation and Embryology Authority licensed centres providing IVF/intracytoplasmic sperm injection (ICSI) in the UK (n = 79).

METHODS

A survey was designed that sought to determine how recurrent treatment failure was defined and which, if any, investigations were initiated. Furthermore, we asked which therapeutic options were subsequently recommended.

MAIN OUTCOME MEASURES

Definition of recurrent treatment failure. Investigations undertaken. Clinical or embryology changes recommended following recurrent treatment failure.

RESULTS

The response rate was 82%. The most common definition was three unsuccessful IVF cycles (range 2-6). Nineteen percent included frozen embryo replacements (FERs) in this figure. Anticardiolipin antibodies and lupus anticoagulant were the most frequent investigations suggested, followed by hysteroscopy and karyotype. A majority of centres would use a different treatment strategy in a subsequent cycle with blastocyst culture and assisted hatching being most popular.

CONCLUSIONS

The results of this survey suggest that there is considerable variation in the approach to investigation and management of recurrent IVF treatment failure in the UK, although in some areas (e.g. the definition) there was broad concordance. Not all of these approaches are evidence based.

Impact of assisted hatching on ART outcome in women with endometriosis

BACKGROUND

Assisted hatching can improve the implantation rate in cycles with poor outcome. The impact of assisted hatching in embryos from women with endometriosis is not known. Therefore, the hypothesis that the implantation potential of embryos obtained from women with endometriosis can be improved with assisted hatching was tested.

METHODS

In a prospective randomized study, transfer embryos obtained from 60 women with endometriosis were hatched using a laser system and compared to embryos obtained from patients with the same diagnosis which were left intact (n = 30).

RESULTS

The characteristics of cycles were similar between groups. The pregnancy (40% zona intact, 28.3% assisted hatching), and implantation rates (19.4% zona intact, 17.8% assisted hatching) did not differ in endometriosis cycles regardless of assisted hatching.

CONCLUSION

Assisted hatching does not improve outcome in women with endometriosis undergoing assisted reproduction.

Embryo afterloading: a refinement in embryo transfer technique that may increase clinical pregnancy

OBJECTIVE

Given the importance of ET technique during assisted reproductive technology cycles, we evaluated the effect of embryo afterloading subsequent to placement of the ET catheter on pregnancy rates vs. a standard direct ET.

DESIGN

Retrospective cohort analysis.

SETTING

University-based assisted reproductive technology program.

PATIENT(S)

Patients undergoing a fresh nondonor day 3 ET by a single provider over a 1-year period.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy.

RESULT(S)

One hundred twenty-seven patients met inclusion criteria, and the overall pregnancy rate was 46.5%. There was no difference between the two groups with respect to age, basal FSH, or number of embryos transferred. The ET method used was at the discretion of the provider. There was no difference between the two groups in the presence of blood on the transfer catheter. However, there were significantly more transfer catheters with mucus contamination in the direct transfer group (25.58% vs. 5.95%). The clinical pregnancy rate in the group with ET using the afterloading technique was higher than in the direct ET group (52.4% vs. 34.9%).

CONCLUSION(S)

There was a trend toward an increase in pregnancy rate when an embryo afterloading technique was used. A prospective randomized trial is needed to examine this issue.

Pronuclear scoring as a predictor of embryo development

Many strategies have been proposed for the selection of viable embryos for transfer in human assisted reproduction. These have included morphological scoring criteria for day 1, 2, 3 and 5 embryos or combinations of these. Other strategies have used predictors such as timing of certain key events, as with early cleavage to the 2-cell, development to the 8-cell stage or patterns of fragmentation. All have shown some correlations with implantation. However, the overall success of these methods is still limited, with over 50% of all transferred embryos failing to implant. The use of pronuclear oocyte morphology has shown correlations with implantation and development to the blastocyst stage. The key aspects of pronuclear scoring, namely the presence of a cytoplasmic halo, the orientation of the nuclei in relation to the polar bodies and the size, number and pattern of distribution of nucleolar precursor bodies (NPB) in the nuclei were related to day 2,3 and 5 development, rate of development and day 3 and 5 morphology in a retrospective study. The pattern of the NPB or Z-score and the presence/absence of a halo had a significant effect on the rate of development on day 3 and day 5 and on the overall embryo morphology score. Low Z-score resulted in slow development, poor blastocyst formation and low morphology scores. The absence of a halo also resulted in slow and poor development, poor morphology, increased fragmentation and increased numbers of poor Z-scored embryos. The use of PN scoring can help predict embryos that have poor developmental potential, aid in early selection and may indicate the health of the oocyte.