Non-invasive imaging of human embryos before embryonic genome activation predicts development to the blastocyst stage

Genomic insights into chromatin reprogramming to totipotency in embryos

Ladstätter and Tachibana discuss changes in DNA methylation, chromatin accessibility, and topological architecture occurring during the reprogramming to totipotency in the early embryo.

The early embryo is the natural prototype for the acquisition of totipotency, which is the potential of a cell to produce a whole organism. Generation of a totipotent embryo involves chromatin reorganization and epigenetic reprogramming that alter DNA and histone modifications. Understanding embryonic chromatin architecture and how this is related to the epigenome and transcriptome will provide invaluable insights into cell fate decisions. Recently emerging low-input genomic assays allow the exploration of regulatory networks in the sparsely available mammalian embryo. Thus, the field of developmental biology is transitioning from microscopy to genome-wide chromatin descriptions. Ultimately, the prototype becomes a unique model for studying fundamental principles of development, epigenetic reprogramming, and cellular plasticity. In this review, we discuss chromatin reprogramming in the early mouse embryo, focusing on DNA methylation, chromatin accessibility, and higher-order chromatin structure.

High sperm DNA fragmentation delays human embryo kinetics when oocytes from young and healthy donors are microinjected

BACKGROUND

Time-lapse monitoring (TLM) technology has been implemented in the clinical setting for the culture and selection of human embryos. Many studies have assessed the association between sperm DNA fragmentation (sDNAf) and clinical outcomes after ART, but little is known about the influence of sDNA on embryo morphokinetics.

OBJECTIVES

The objective of this retrospective study, which includes 971 embryos from 135 consecutive ICSI cycles (56 cases with own oocytes, 79 with oocytes from young and healthy donors), was to assess if sDNAf has an impact on embryo morphokinetics.

MATERIALS AND METHODS

Samples used to perform ICSI were analyzed by the flow cytometry TUNEL assay, and embryo development was assessed through an EmbyoScope^® system. The association between sDNAf and the timings of cell cleavage was analyzed by categorizing the first variable into quartiles: ≤6.50%; 6.51-10.70%; 10.71-20.15%; >20.15%.

RESULTS

In cases where sDNAf was above 20.15% (the upper quartile), embryos derived from donated oocytes (n = 644) showed significantly slower divisions. Such association was not observed in embryos obtained from the patients' own oocytes (n = 327). The embryo cleavage pattern (either normal, direct from 1 to 3 blastomeres, direct from 1 to 4 blastomeres, incomplete, reversed or asynchronous) was independent of the sDNAf level. Blastocyst arrival rate was 63.0% and the rate of good quality embryos (transferred and frozen embryos divided by the number of zygotes) was 45.49%. Neither parameter was related to the levels of sDNAf.

DISCUSSION

According to our results, the association between high sDNAf and donated oocytes led to delayed cell division. To our knowledge, this is the first study suggesting that sDNAf can delay human embryo cleavage timings when oocytes from donors are inseminated.

CONCLUSIONS

This finding may indicate that, in the presence of increased DNA damage, time is needed before the first embryonic cell division for the activation of the optimal DNA repairing machinery in higher quality oocytes.

Inverted pyramid of prenatal care - is it enough? Should it be - extended inverted pyramid of prenatal care?

In recent years, the idea of the inverted pyramid of prenatal care and monitoring has emerged, for the purpose of prediction and prevention, early detection and treatment of health disorders of the fetus. Is this enough? If we analyze the period behind us, progress has been made in the field of detection of multiple pregnancies, dating of pregnancy and prenatal detection of chromosomal and structural fetal disorders, as well as a small amount of progress in terms of prediction and prevention of preeclampsia. If these disorders are the consequence of the disturbed or dysfunctional placentation, they are rooted at the time of implantation. This means that the changes that lead to the dysfunctional implantation should be sought in the pre-implantation period, in relation between the embryo and the endometrium. An extended inverted pyramid is necessary to find better results in perinatal medicine. This means that the interventions should be focused on the preconception and peri-implantation periods. The therapy should be on the subcellular and genetic level by applying the latest biotechnological procedures. It is possible that the time is approaching when the listed disorders of a pregnancy will be the indications for the application of a non stimulated in-vitro fertilization (IVF) (without ovary stimulating medication) with the use of new biotechnological achievements.

Effect of morphokinetics and morphological dynamics of cleavage stage on embryo developmental potential: A time-lapse study

OBJECTIVE

Using a non-invasive method to select the most competent embryo is essential in in vitro fertilization (IVF). Since the beginning of clinical application of time-lapse technology, several studies have proposed models using the time-lapse imaging system for predicting the IVF outcome. This study used both morphokinetic and morphological dynamic parameters to select embryos with the highest developmental potential.

MATERIALS AND METHODS

A total of 23 intracytoplasmic sperm injection treatment cycles with 138 fertilized oocytes were included in this study. All embryos were cultured to the blastocyst stage, and embryo development was recorded every 10 min by using a time-lapse imaging system. Morphokinetic parameters and eight major abnormal division behaviors were studied to determine their effects on blastocyst formation. The most influential variables were used in hierarchical classification for blastocyst formation prediction.

RESULTS

Several parameters were significantly related to the developmental potential. Embryos with the timing of pronuclear fading (tPNF) of >26.4 h post insemination (hpi), the timing of division to two cells (t2) of >29.1 hpi, and the timing of division to four cells (t4) of >41.3 hpi showed the lowest blastocyst formation rate. The abnormal division behaviors of fragmentation >50%, direct cleavage, reverse cleavage, and delayed division or developmental arrest were found to be detrimental to blastocyst formation. On the basis of these results, we propose a hierarchical model classification, in which embryos are classified into groups A-D according to their developmental potential. The blastocyst formation rates of groups A, B, C, and D were 80.0%, 77.8%, 53.7%, and 22.2% (p < 0.001). The good blastocyst rates of groups A, B, C, and D were 60.0%, 44.4%, 14.6%, and 11.1% (p = 0.007).

CONCLUSION

We propose a hierarchical classification system for blastocyst formation prediction, which provides information for embryo selection by using a time-lapse imaging system.

Hydrogel-Based Bioprocess for Scalable Manufacturing of Human Pluripotent Stem Cell-Derived Neural Stem Cells

Neural stem cells derived from human pluripotent stem cells (hPSC-NSCs) are of great value for modeling diseases, developing drugs, and treating neurological disorders. However, manufacturing high-quantity and -quality hPSC-NSCs, especially for clinical applications, remains a challenge. Here, we report a chemically defined, high-yield, and scalable bioprocess for manufacturing hPSC-NSCs. hPSCs are expanded and differentiated into NSCs in microscale tubes made with alginate hydrogels. The tubes are used to isolate cells from the hydrodynamic stresses in the culture vessel and limit the radial diameter of the cell mass to less than 400 μm to ensure efficient mass transport during the culture. The hydrogel tubes provide uniform, reproducible, and cell-friendly microspaces and microenvironments for cells. With this new technology, we showed that hPSC-NSCs could be produced in 12 days with high viability (∼95%), high purity (>90%), and high yield (∼5 × 10⁸ cells/mL of microspace). The volumetric yield is about 250 times more than the current state-of-the-art. Whole transcriptome analysis and quantitative real-time polymerase chain reaction showed that hPSC-NSCs made by this process had a similar gene expression to hPSC-NSCs made by the conventional culture technology. The produced hPSC-NSCs could mature into both neurons and glial cells in vitro and in vivo. The process developed in this paper can be used to produce large numbers of hPSC-NSCs for various biomedical applications in the future.

External validation of a time-lapse model; a retrospective study comparing embryo evaluation using a morphokinetic model to standard morphology with live birth as endpoint

Objective

To validate a morphokinetic implantation model developed for EmbryoScope on embryos with known outcome, compared to standard morphology in a retrospective single center study.

Methods

Morphokinetic annotation of 768 embryos with known outcome between 2013 -2015; corresponding to 116 D3 fresh embryos, 80 D6 frozen blastocysts, and 572 D5 blastocysts, fresh or frozen. The embryos were ranked by the KIDScore into five classes, KID1-5, and grouped into four classes based on standard morphology. Pregnancy rates, clinical pregnancy rates and live birth rates were compared. Combinations of morphology and morphokinetics were evaluated for implantation rates and live births.

Results

Live birth rate increased with increasing KIDScore, from 19% for KID1 to 42% for KID5. Of all live births, KID5 contributed with 71%, KID4 with 20%, KID3 with 4%, KID2 with 4%, and KID1 with 2%. For morphology, the corresponding figure was 43% for Top Quality, 47% for Good Quality, 4% for Poor Quality, and 5% for Slow embryos. For day 3 embryos, KID5 embryos had the highest live birth rates, and contributed to 83% of the live births; whereas the second best morphological class had the highest live birth rate and contributed to most of the live births. For blastocysts, the KIDScore and morphology performed equally well. Combining morphology and morphokinetics indicated stronger predictive power for morphokinetics.

Conclusions

Overall, the KIDScore correlates with both implantation and live birth in our clinical setting. Compared to morphology, the KIDScore was superior for day 3 embryos, and equally good for blastocysts at predicting live births.

Morphology vs morphokinetics: a retrospective comparison of inter-observer and intra-observer agreement between embryologists on blastocysts with known implantation outcome

Objective

Our primary aim was to compare the morphology and morphokinetics on inter- and intra-observer agreement for blastocyst with known implantation outcome. Our secondary aim was to validate the morphokinetic parameters' ability to predict pregnancy using a previous published selection algorithm, and to compare this to standard morphology assessments.

Methods

Two embryologists made independent blinded annotations on two occasions using time-lapse images and morphology evaluations using the Gardner Schoolcraft criteria of 99 blastocysts with known implantation outcome. Inter- and intra-observer agreement was calculated and compared using the two methods. The embryos were grouped based on their morphological score, and on their morphokinetic class using a previous published selection algorithm. The implantation rates for each group was calculated and compared.

Results

There was moderate agreement for morphology, with agreement on the same embryo score in 55 of 99 cases. The highest agreement rate was found for expansion grade, followed by trophectoderm and inner cell mass. Correlation with pregnancy was inconclusive. For morphokinetics, almost perfect agreement was found for early and late embryo development events, and strong agreement for day-2 and day-3 events. When applying the selection algorithm, the embryo distributions were uneven, and correlation to pregnancy was inconclusive.

Conclusions

Time-lapse annotation is consistent and accurate, but our external validation of a previously published selection algorithm was unsuccessful.

Euploid embryos selected by an automated time-lapse system have superior SET outcomes than selected solely by conventional morphology assessment

PURPOSE

We investigated if automated TLI selection may be a valuable strategy to identify those euploid embryos with the best chances of success.

METHODS

This is a unicentric and retrospective study involving 244 patients undergoing preimplantational genetic screening (PGS) cycles with autologous oocytes or oocyte donation (OD) with single euploid embryo transferred. We examined euploid embryos selected for transfer based on morphology evaluation alone (PGS-only; control group) or by assessment using an automated TLI system (Eeva™; PGS-TLI group).

RESULTS

In both, autologous oocytes and OD patients, significantly better implantation and clinical and ongoing pregnancy rates were obtained in the PGS-TLI group when euploid embryos with high implantation potential as predicted by the automated TLI System (Eeva™) were transferred compared with the PGS-only group. This improvement was also observed when only transfers of good morphological quality embryos were compared. TLI categories showed significant differences on blastocyst formation and euploidy rate.

CONCLUSIONS

Automated TLI combined with PGS is a useful prognostic tool to identify euploid embryos with the highest potential for implantation and pregnancy. Further, these results provide evidence that a healthy pregnancy does not only depend upon normal chromosomal status.

A Scalable and Efficient Bioprocess for Manufacturing Human Pluripotent Stem Cell-Derived Endothelial Cells

Endothelial cells (ECs) are of great value for cell therapy, tissue engineering, and drug discovery. Obtaining high-quantity and -quality ECs remains very challenging. Here, we report a method for the scalable manufacturing of ECs from human pluripotent stem cells (hPSCs). hPSCs are expanded and differentiated into ECs in a 3D thermoreversible PNIPAAm-PEG hydrogel. The hydrogel protects cells from hydrodynamic stresses in the culture vessel and prevents cells from excessive agglomeration, leading to high-culture efficiency including high-viability (>90%), high-purity (>80%), and high-volumetric yield (2.0 × 10⁷ cells/mL). These ECs (i.e., 3D-ECs) had similar properties as ECs made using 2D culture systems (i.e., 2D-ECs). Genome-wide gene expression analysis showed that 3D-ECs had higher expression of genes related to vasculature development, extracellular matrix, and glycolysis, while 2D-ECs had higher expression of genes related to cell proliferation.

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hPSCs can be differentiated into endothelial cells in 3D thermoreversible hydrogels

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The differentiation efficiency is similar to this in 2D cultures

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The global gene expression and phenotypes are similar to ECs made in 2D cultures

Are computational applications the "crystal ball" in the IVF laboratory? The evolution from mathematics to artificial intelligence

Mathematics rules the world of science. Innovative technologies based on mathematics have paved the way for implementation of novel strategies in assisted reproduction. Ascertaining efficient embryo selection in order to secure optimal pregnancy rates remains the focus of the in vitro fertilization scientific community and the strongest driver behind innovative approaches. This scoping review aims to describe and analyze complex models based on mathematics for embryo selection, devices, and software most widely employed in the IVF laboratory and algorithms in the service of the cutting-edge technology of artificial intelligence. Despite their promising nature, the practicing embryologist is the one ultimately responsible for the success of the IVF laboratory and thus the one to approve embracing pioneering technologies in routine practice. Applied mathematics and computational biology have already provided significant insight into the selection of the most competent preimplantation embryo. This review describes the leap of evolution from basic mathematics to bioinformatics and investigates the possibility that computational applications may be the means to foretell a promising future for the IVF clinical practice.

Combinatorial Contact Cues Specify Cell Division Orientation by Directing Cortical Myosin Flows

Cell division axes during development are specified in different orientations to establish multicellular assemblies, but the mechanisms that generate division axis diversity remain unclear. We show here that patterns of cell contact provide cues that diversify cell division orientation by modulating cortical non-muscle myosin flow. We reconstituted in vivo contact patterns using beads or isolated cells to show two findings. First, we identified three contact-dependent cues that pattern cell division orientation and myosin flow: physical contact, contact asymmetry, and a Wnt signal. Second, we experimentally demonstrated that myosin flow generates forces that trigger plasma membrane movements and propose that their anisotropy drives cell division orientation. Our data suggest that contact-dependent control of myosin specifies the division axes of Caenorhabditis elegans AB, ABa, EMS cells, and the mouse AB cell. The contact pattern-dependent generation of myosin flows, in concert with known microtubule/dynein pathways, may greatly expand division axis diversity during development.

Single cell expression analysis of primate-specific retroviruses-derived HPAT lincRNAs in viable human blastocysts identifies embryonic cells co-expressing genetic markers of multiple lineages

Chromosome instability and aneuploidies occur very frequently in human embryos, impairing proper embryogenesis and leading to cell cycle arrest, loss of cell viability, and developmental failures in 50–80% of cleavage-stage embryos. This high frequency of cellular extinction events represents a significant experimental obstacle challenging analyses of individual cells isolated from human preimplantation embryos. We carried out single cell expression profiling of 241 individual cells recovered from 32 human embryos during the early and late stages of viable human blastocyst (VHB) differentiation. Classification of embryonic cells was performed solely based on expression patterns of human pluripotency-associated transcripts (HPAT), which represent a family of primate-specific transposable element-derived lincRNAs highly expressed in human embryonic stem cells and regulating nuclear reprogramming and pluripotency induction. We then validated our findings by analyzing transcriptomes of 1,708 individual cells recovered from more than 100 human embryos and 259 mouse cells from more than 40 mouse embryos at different stages of preimplantation embryogenesis. HPAT's expression-guided spatiotemporal reconstruction of human embryonic development inferred from single-cell expression analysis of VHB differentiation enabled identification of telomerase-positive embryonic cells co-expressing key pluripotency regulatory genes and genetic markers of three major lineages. Follow-up validation analyses confirmed the emergence in human embryos prior to lineage segregation of telomerase-positive cells co-expressing genetic markers of multiple lineages. Observations reported in this contribution support the hypothesis of a developmental pathway of creation embryonic lineages and extraembryonic tissues from telomerase-positive pre-lineage cells manifesting multi-lineage precursor phenotype.

High reliability of morphokinetic annotations among embryologists

STUDY QUESTION

Are morphokinetic measurements of time lapse-videos of human embryos comparable among operators?

SUMMARY ANSWER

There is little variation among morphokinetic measurements taken by different operators when analyzing the same time lapse-videos of human embryos.

WHAT IS KNOWN ALREADY

Morphokinetic analysis of preimplantation embryo development is a complementary method of embryo assessment increasingly used in IVF laboratories. Time-lapse videos of embryo development are normally viewed by trained embryologists and annotated with the times when specific developmental events occur. Such annotations form the basis of embryo selection algorithms, used to rank the embryos for transfer. It is unknown whether the reliability of morphokinetic annotations is related to the morphological characteristics of the analyzed embryo or to the ability of the embryologists performing the annotation. One study so far reported the reliability of morphokinetic annotations among three embryologists using the time-lapse system (TLS), but larger studies with different setups are needed to address this issue further.

STUDY DESIGN SIZE DURATION

A prospective study was carried out between October 2015 and June 2016. Six embryologists with various degrees of experience in static, morphology-based evaluation, individually annotated the same 93 videos of preimplantation development, corresponding to 18 IVF/ICSI cycles, recorded with a TLS.

PARTICIPANTS/MATERIALS SETTING METHODS

Times of second polar body extrusion, appearance and disappearance of pronuclei, and embryo cleavages (times from 2-cell to 5-cell stage: t2, t3, t4, t5) were annotated. Each embryologist was blinded to the annotations of the others. Intra- and inter-observer agreement was evaluated by computing intra-class correlation coefficients (ICCs).

MAIN RESULTS AND THE ROLE OF CHANCE

In the inter-observer analysis, most ICCs obtained were higher than 0.80, indicating a high level of agreement: t2: 0.93; t3: 0.80; t4: 0.89; t5: 0.89; disappearance of two pronuclei: 0.98. However, the ICCs obtained for second polar body extrusion and the appearance of two pronuclei annotations was lower: 0.51 and 0.63, respectively, indicating an average level of agreement. The ICCs obtained from the intra-observer analysis were also higher than 0.80 (t2: 0.96; t3: 0.89; t4: 0.88; t5: 0.86; disappearance of two pronuclei: 0.96). The ICCs obtained from second polar body extrusion and the appearance of two pronuclei annotations were 0.77 and 0.66, respectively. These results indicate that developmental timings, annotated in time-lapse videos, are highly reliable both within and among observers.

LIMITATIONS REASONS FOR CAUTION

The events at the developmental stages from 6-cells to blastocyst were not evaluated; since some morphokinetic algorithms use times past the 6-cell stage in their calculations, further studies should be carried out to understand the variations among observers in these cases.

WIDER IMPLICATIONS OF THE FINDINGS

Time-lapse measurement should be as objective as possible, especially for the first embryo cleavages, because they are often measured to define algorithms to assess the embryonic implantation potential. Our results show that measurements using this particular TLS are consistent and reliable both within and among operators.

STUDY FUNDING/COMPETING INTERESTS

None.

TRIAL REGISTRATION NUMBER

Not applicable.

Prospective study of automated versus manual annotation of early time-lapse markers in the human preimplantation embryo

STUDY QUESTION

How does automated time-lapse annotation (Eeva™) compare to manual annotation of the same video images performed by embryologists certified in measuring durations of the 2-cell (P2; time to the 3-cell minus time to the 2-cell, or t3-t2) and 3-cell (P3; time to 4-cell minus time to the 3-cell, or t4-t3) stages?

SUMMARY ANSWER

Manual annotation was superior to the automated annotation provided by Eeva™ version 2.2, because manual annotation assigned a rating to a higher proportion of embryos and yielded a greater sensitivity for blastocyst prediction than automated annotation.

WHAT IS KNOWN ALREADY

While use of the Eeva™ test has been shown to improve an embryologist's ability to predict blastocyst formation compared to Day 3 morphology alone, the accuracy of the automated image analysis employed by the Eeva™ system has never been compared to manual annotation of the same time-lapse markers by a trained embryologist.

STUDY DESIGN, SIZE, DURATION

We conducted a prospective cohort study of embryos (n = 1477) cultured in the Eeva™ system (n = 8 microscopes) at our institution from August 2014 to February 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Embryos were assigned a blastocyst prediction rating of High (H), Medium (M), Low (L), or Not Rated (NR) by Eeva™ version 2.2 according to P2 and P3. An embryologist from a team of 10, then manually annotated each embryo and if the automated and manual ratings differed, a second embryologist independently annotated the embryo. If both embryologists disagreed with the automated Eeva™ rating, then the rating was classified as discordant. If the second embryologist agreed with the automated Eeva™ score, the rating was not considered discordant. Spearman's correlation (ρ), weighted kappa statistics and the intra-class correlation (ICC) coefficients with 95% confidence intervals (CI) between Eeva™ and manual annotation were calculated, as were the proportions of discordant embryos, and the sensitivity, specificity, positive predictive value (PPV) and NPV of each method for blastocyst prediction.

MAIN RESULTS AND THE ROLE OF CHANCE

The distribution of H, M and L ratings differed by annotation method (P < 0.0001). The correlation between Eeva™ and manual annotation was higher for P2 (ρ = 0.75; ICC = 0.82; 95% CI 0.82-0.83) than for P3 (ρ = 0.39; ICC = 0.20; 95% CI 0.16-0.26). Eeva™ was more likely than an embryologist to rate an embryo as NR (11.1% vs. 3.0%, P < 0.0001). Discordance occurred in 30.0% (443/1477) of all embryos and was not associated with factors such as Day 3 cell number, fragmentation, symmetry or presence of abnormal cleavage. Rather, discordance was associated with direct cleavage (P2 ≤ 5 h) and short P3 (≤0.25 h), and also factors intrinsic to the Eeva™ system, such as the automated rating (proportion of discordant embryos by rating: H: 9.3%; M: 18.1%; L: 41.3%; NR: 31.4%; P < 0.0001), microwell location (peripheral: 31.2%; central: 23.8%; P = 0.02) and Eeva™ microscope (n = 8; range 22.9-42.6%; P < 0.0001). Manual annotation upgraded 82.6% of all discordant embryos from a lower to a higher rating, and improved the sensitivity for predicting blastocyst formation.

LIMITATIONS, REASONS FOR CAUTION

One team of embryologists performed the manual annotations; however, the study staff was trained and certified by the company sponsor. Only two time-lapse markers were evaluated, so the results are not generalizable to other parameters; likewise, the results are not generalizable to future versions of Eeva™ or other automated image analysis systems.

WIDER IMPLICATIONS OF THE FINDINGS

Based on the proportion of discordance and the improved performance of manual annotation, clinics using the Eeva™ system should consider manual annotation of P2 and P3 to confirm the automated ratings generated by Eeva™.

STUDY FUNDING/COMPETING INTEREST(S)

These data were acquired in a study funded by Progyny, Inc. There are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Live-cell imaging of nuclear-chromosomal dynamics in bovine in vitro fertilised embryos

Nuclear/chromosomal integrity is an important prerequisite for the assessment of embryo quality in artificial reproductive technology. However, lipid-rich dark cytoplasm in bovine embryos prevents its observation by visible light microscopy. We performed live-cell imaging using confocal laser microscopy that allowed long-term imaging of nuclear/chromosomal dynamics in bovine in vitro fertilised (IVF) embryos. We analysed the relationship between nuclear/chromosomal aberrations and in vitro embryonic development and morphological blastocyst quality. Three-dimensional live-cell imaging of 369 embryos injected with mRNA encoding histone H2B-mCherry and enhanced green fluorescent protein (EGFP)-α-tubulin was performed from single-cell to blastocyst stage for eight days; 17.9% reached the blastocyst stage. Abnormalities in the number of pronuclei (PN), chromosomal segregation, cytokinesis, and blastomere number at first cleavage were observed at frequencies of 48.0%, 30.6%, 8.1%, and 22.2%, respectively, and 13.0%, 6.2%, 3.3%, and 13.4%, respectively, for abnormal embryos developed into blastocysts. A multivariate analysis showed that abnormal chromosome segregation (ACS) and multiple PN correlated with delayed timing and abnormal blastomere number at first cleavage, respectively. In morphologically transferrable blastocysts, 30-40% of embryos underwent ACS and had abnormal PN. Live-cell imaging may be useful for analysing the association between nuclear/chromosomal dynamics and embryonic development in bovine embryos.

Single-cell RNA sequencing reveals developmental heterogeneity of blastomeres during major genome activation in bovine embryos

Embryonic development is initially controlled by maternal RNAs and proteins stored in the oocyte, until gene products gradually generated by the embryo itself take over. Major embryonic genome activation (EGA) in bovine embryos occurs at the eight- to 16-cell stage. Morphological observations, such as size of blastomeres and distribution of microvilli, suggested heterogeneity among individual cells already at this developmental stage. To address cell heterogeneity on the transcriptome level, we performed single-cell RNA sequencing of 161 blastomeres from 14 in vitro produced bovine embryos at Day 2 (n = 6) and Day 3 (n = 8) post fertilization. Complementary DNA libraries were prepared using the Single-Cell RNA-Barcoding and Sequencing protocol and sequenced. Non-supervised clustering of single-cell transcriptome profiles identified six clusters with specific sets of genes. Most embryos were comprised of cells from at least two different clusters. Sorting cells according to their transcriptome profiles resulted in a non-branched pseudo-time line, arguing against major lineage inclination events at this developmental stage. In summary, our study revealed heterogeneity of transcriptome profiles among single cells in bovine Day 2 and Day 3 embryos, suggesting asynchronous blastomere development during the phase of major EGA.

An automated blastomere identification method for the evaluation of day 2 embryos during IVF/ICSI treatments

PURPOSE

Evaluation of human embryos is one of the most important challenges in vitro fertilization (IVF) programs. The morphology and the morphokinetic parameters of the early cleaving embryo are of critical clinical importance. This stage spans the first 48 h post-fertilization, in which the embryo is dividing in smaller blastomeres at specific time-points. The morphology, in combination with the symmetry of the blastomeres seems to be powerful features with strong prognostic value for embryo evaluation. To date, the identification of these features is based on human inspection in timed intervals, at best using camera systems that simply work as surveillance systems without any precise alerting and decision support mechanisms. The purpose of the study presented in this paper was to develop a computer vision technique to automatically detect and identify the most suitable cleaving embryos (preferably at day 2 post-fertilization) for embryo transfer (ET) during IVF/ICSI treatments.

METHODS AND RESULTS

To this end, texture and geometrical features were used to localize and analyze the whole cleaving embryo in 2D grayscale images captured during in vitro embryo formation. Because of the ellipsoidal nature of blastomeres, the contour of each blastomere was modeled with an optimal fitting ellipse while the mean eccentricity of all ellipses is computed. The mean eccentricity in combination with the number of blastomeres forms the feature space on which the final criterion for the embryo evaluation was based.

CONCLUSIONS

Experimental results with low quality 2D grayscale images demonstrated the effectiveness of the proposed technique and provided evidence of a novel automated approach for predicting embryo quality.

Pronuclear pattern does not predict morphokinetics behavior in human embryos

The purpose was to investigate the correlation between pronuclei (PN) morphology and morphokinetic behaviors of derived embryos with time lapse monitoring (TLM) in assisted reproduction setting. Over time, PN morphology from PN appearance (PNA) to PN fading (PNF), PNF according to size, contact, number and position of nuclear precursor bodies (NPBs) within each PN and morphokinetics variables, including absolute time points, relative timing parameters, cleavage patterns and arrest rate, were evaluated using TLM. There were insignificant relationship between morphokinetics variables including tBP2, tPNA, tPNF, t2, t3, t4, t5, t6, t7, t8, S1, CC2, S2 and Z scoring according Z1 to Z4 (p > .05). Also, an insignificant relationship was noticed between uneven blastomeres, reverse cleavage embryos and Z scoring (p > .05). However, there were significant correlations between the rates of direct and arbitrary cleavage as well as arrested embryos and Z scores. Combined PN morphology and embryo kinetic evaluation were suggested in assisted reproduction programs.

Scalable and physiologically relevant microenvironments for human pluripotent stem cell expansion and differentiation

Human pluripotent stem cells (hPSCs) are required in large numbers for various biomedical applications. However, the scalable and cost-effective culturing of high quality hPSCs and their derivatives remains very challenging. Here, we report a novel and physiologically relevant 3D culture system (called the AlgTube cell culture system) for hPSC expansion and differentiation. With this system, cells are processed into and cultured in microscale alginate hydrogel tubes that are suspended in the cell culture medium in a culture vessel. The hydrogel tubes protect cells from hydrodynamic stresses in the culture vessel and limit the cell mass smaller than 400 μm in diameter to ensure efficient mass transport, creating cell-friendly microenvironments for growing cells. This system is simple, scalable, highly efficient, defined and compatible with the current good manufacturing practices. Under optimized culture conditions, the AlgTubes enabled long-term culture of hPSCs (>10 passages, >50 days) with high cell viability, high growth rate (1000-fold expansion over 10 days per passage), high purity (>95% Oct4+) and high yield (5.0 × 10⁸ cells ml^-1), all of which offer considerable advantages compared to current approaches. Moreover, the AlgTubes enabled directed differentiation of hPSCs into various tissue cells. This system can be readily scaled to support research from basic biological study to clinical development and the future industry-scale production.

Blastulation timing is associated with differential mitochondrial content in euploid embryos

PURPOSE

Preimplantation genetic screening (PGS) and assessment of mitochondrial content (MC) are current methods for selection of the best embryos for transfer. Studies suggest that time-lapse morphokinetics (TLM) may also be helpful for selecting embryos more likely to implant. In our study, we sought to examine the relationship between TLM parameters and MC to determine if they could be used adjunctively in embryo selection. We also examined the relationship between MC with ploidy and blastulation.

METHODS

Cryopreserved human embryos at the zygote stage were thawed and cultured in a time-lapse system. Blastomere and trophectoderm biopsies were performed on days 3 and 6. Biopsied cells and all whole embryos from day 6 were analyzed for MC (ratio of mitochondrial to nuclear DNA) and ploidy using next-generation sequencing.

RESULTS

In embryos, MC per cell declined between day 3 and day 6. While early cleavage parameters did not predict MC, embryos with longer blastulation timing had higher MC on day 6. Day 6 MC was lower in euploid vs. aneuploid embryos and lower in blastocysts vs. arrested embryos.

CONCLUSIONS

A lower MC at the blastocyst stage was associated with euploid status and blastocyst formation, indicating better embryo quality compared to those with a higher MC. Higher MC in aneuploid and arrested embryos may be explained by slower cell division or degradation of genomic DNA over time. Blastulation timing may be helpful for selection of higher quality embryos. Combining blastulation timing and MC along with morphologic grading and euploid status may offer a new direction in embryo selection.

Assessing efficacy of day 3 embryo time-lapse algorithms retrospectively: impacts of dataset type and confounding factors

This study investigated the efficacy of four published day 3 embryo time-lapse algorithms based on different types of datasets (known implantation data [KID] and single embryo transfer [SET]), and the confounding effect of female age and conventional embryo morphology. Four algorithms were retrospectively applied to three types of datasets generated at Fertility North between February 2013 and December 2014: (a) KID dataset (n = 270), (b) a subset of SET (n = 144, end-point = implantation), and (c) SET (n = 144, end-point = live birth), respectively. All four algorithms showed progressively reduced predictive power (expressed as area under the receiver operating characteristics curve and 95% confidence interval [CI]) after application to the three datasets (a-c): Liu (0.762 [0.701-0.824] vs. 0.724 [0.641-0.807] vs. 0.707 [0.620-0.793]), KIDScore (0.614 [0.539-0.688] vs. 0.548 [0.451-0.645] vs. 0.536 [0.434-0.637]), Meseguer (0.585 [0.508-0.663] vs. 0.56 [0.462-0.658] vs. 0.549 [0.445-0.652]), and Basile (0.582 [0.505-0.659] vs. 0.519 [0.421-0.618] vs. 0.509 [0.406-0.612]). Furthermore, using KID dataset, the association (expressed as odds ratio and 95% CI) between time-lapse algorithms and implantation outcomes lost statistical significance after adjusting for conventional embryo morphology and female age in 3 of the 4 algorithms (KIDScore 1.832 [1.118-3.004] vs. 1.063 [0.659-1.715], Meseguer 1.150 [1.021-1.295] vs. 1.122 [0.981-1.284] and Basile 1.122 [1.008-1.249] vs. 1.038 [0.919-1.172]). In conclusion, SET is a preferred dataset to KID when developing or validating time-lapse algorithms, and day 3 conventional embryo morphology and female age should be considered as confounding factors.

Time-Lapse Imaging for the Detection of Chromosomal Abnormalities in Primate Preimplantation Embryos

The use of time-lapse microscopic imaging has proven to be a powerful tool for the study of mitotic divisions and other cellular processes across diverse species and cell types. Although time-lapse monitoring (TLM) of human preimplantation development was first introduced to the in vitro fertilization (IVF) community several decades ago, it was not until relatively recently that TLM systems were commercialized for clinical embryology purposes. Traditionally, human IVF embryos are assessed by successful progression and morphology under a stereomicroscope at distinct time points prior to selection for transfer. Due to the high frequency of aneuploidy, embryos may also be biopsied at the cleavage or blastocyst stage for preimplantation genetic screening (PGS) of whole and/or partial chromosomal abnormalities. However, embryo biopsy is invasive and can hinder subsequent development, and there are additional concerns over chromosomal mosaicism and resolution with PGS. Moreover, embryos are typically outside of the incubator in suboptimal culture conditions for extended periods of time during these procedures. With TLM systems, embryos remain in the stable microenvironment of an incubator and are simultaneously imaged for noninvasive embryo evaluation using a fraction of the light exposure as compared to a stereomicroscope. Each image is then compiled into a time-lapse movie, the information from which can be extrapolated to correlate morphological, spatial, and temporal parameters with embryo quality and copy number status. Here, we describe the various TLM systems available for clinical and/or research use in detail and provide step-by-step instructions on how the measurement of specific timing intervals and certain morphological criteria can be implemented into IVF protocols to enhance embryo assessment and avoid the selection of aneuploid embryos. We also discuss the biological significance of processes unique to mitotically dividing embryos and the likelihood that complex chromosomal events such as chromothripsis occur during preimplantation development in humans and other mammals, particularly nonhuman primates.

Embryo culture conditions are significantly improved during uninterrupted incubation: A randomized controlled trial

A parallel group superiority prospective randomised controlled trial was devised to compare the culture characteristics of human pre-implantation stage embryos during uninterrupted culture in a time lapse incubator (TLI) versus the conventional model of interrupted culture in a standard incubator (SI) under low oxygen tension using a single step medium. 221 patients aged 35-and-under, 124 patients aged between 36 and 39 and 86 patients aged 40-and-over years were randomised and cultured either in a SI or in a TLI. Patients in the three age groups were distributed between the TLI and SI in a 1:1 ratio. The development of embryos on days 2, 3 and 5, and the clinical pregnancy and implantation rates were recorded. The fertilisation rate, development of day 2 and clinical pregnancy rates were similar in both treatments but the 8-cell development rate in all age groups combined (p = 0.016), blastocyst development rate (p = 0.0022) and the implantation rate (p = 0.0022) was significantly higher for the uninterrupted culture. These findings demonstrated significant differences between the two incubation groups. It also indicated less efficacious embryonic development with age in both treatments which appeared more pronounced in the conventional incubator. In conclusion uninterrupted culture is superior compared to the interrupted incubation culture system.

Application of microfluidic technologies to human assisted reproduction

Microfluidics can be considered both a science and a technology. It is defined as the study of fluid behavior at a sub-microliter level and the investigation into its application to cell biology, chemistry, genetics, molecular biology and medicine. There are at least two characteristics of microfluidics, mechanical and biochemical, which can be influential in the field of mammalian gamete and preimplantation embryo biology. These microfluidic characteristics can assist in basic biological studies on sperm, oocyte and preimplantation embryo structure, function and environment. The mechanical and biochemical characteristics of microfluidics may also have practical and/or technical application(s) to assisted reproductive technologies (ART) in rodents, domestic species, endangered species and humans. This review will consider data in mammals, and when available humans, addressing the potential application(s) of microfluidics to assisted reproduction. There are numerous sequential steps in the clinical assisted reproductive laboratory process that work, yet could be improved. Cause and effect relations of procedural inefficiencies can be difficult to identify and/or remedy. Data will be presented that consider microfluidic applications to sperm isolation, oocyte cumulus complex isolation, oocyte denuding, oocyte mechanical manipulation, conventional insemination, intracytoplasmic sperm injection, embryo culture, embryo analysis and oocyte and embryo cryopreservation. While these studies have progressed in animal models, data with human gametes and embryos are significantly lacking. These data from clinical trials are requisite for making future evidence-based decisions regarding the application of microfluidics in human ART.

Comparison of the development of human embryos cultured in either an EmbryoScope or benchtop incubator

PURPOSE

In this current study, our main goal was to establish that EmbryoScope incubation environment is comparable to standard incubation.

METHODS

The development of sibling human zygotes was compared after culture in either a benchtop incubator (SI) or an EmbryoScope time-lapse incubator (ES). Between May 2015 to April 2016, a total of 581 normally fertilized 2PN, pronuclear-stage embryos, from 47 patients were allocated to culture in either a benchtop incubator (SI) or an EmbryoScope incubator (ES).

RESULTS

The development of embryos to cleavage (up to day 3) and blastocyst stages (day 5/6) was compared between the two different incubators. The proportion of good quality embryos was higher in the ES group compared to the SI on day 2 (66.8 vs. 50.5%, P = 0.014) and on day 3 (75.1 vs. 56.0%, P = 0.006). Those differences were statistically significant. A higher proportion of embryos developed to good quality blastocysts when cultured in the EmbryoScope compared to the benchtop (49.4 vs. 42.0%, P = 0.24), but this was not significant. Finally, no significant differences were noted with the proportion of blastocysts chosen for cryopreservation on day 5/6 in the two incubators.

CONCLUSIONS

The findings support the view that the EmbryoScope incubator supports at least equivalent in vitro development of human embryos compared to other standard incubation methods and may promote improved development during early cleavage stages.

Organ size control via hydraulically gated oscillations

Hollow vesicular tissues of various sizes and shapes arise in biological organs such as ears, guts, hearts, brains and even entire organisms. Regulating their size and shape is crucial for their function. Although chemical signaling has been thought to play a role in the regulation of cellular processes that feed into larger scales, it is increasingly recognized that mechanical forces are involved in the modulation of size and shape at larger length scales. Motivated by a variety of examples of tissue cyst formation and size control that show simultaneous growth and size oscillations, we create a minimal theoretical framework for the growth and dynamics of a soft, fluid-permeable, spherical shell. We show that these shells can relieve internal pressure by bursting intermittently, shrinking and re-growing, providing a simple mechanism by which hydraulically gated oscillations can regulate size. To test our theory, we develop an in vitro experimental set-up to monitor the growth and oscillations of a hollow tissue spheroid growing freely or when confined. A simple generalization of our theory to account for irreversible deformations allows us to explain the time scales and the amplitudes of oscillations in terms of the geometry and mechanical properties of the tissue shells. Taken together, our theory and experimental observations show how soft hydraulics can regulate the size of growing tissue shells.

Relief of endoplasmic reticulum stress enhances DNA damage repair and improves development of pre-implantation embryos

Early-cleaving embryos are known to have better capacity to reach the blastocyst stage and produce better quality embryos compared to late-cleaving embryos. To investigate the significance of endoplasmic reticulum (ER) stress on early embryo cleavage kinetics and development, porcine embryos produced in vitro were separated into early- and late-cleaving groups and then cultured in the absence or presence of the ER stress inhibitor tauroursodeoxycholic acid (TUDCA). Developing embryos were collected at days 3 to 7 of culture for assessment of ER stress status, incidence of DNA double-strand breaks (DSBs), development and total cell number. In the absence of TUDCA treatment, late-cleaving embryos exhibited ER stress, higher incidence of DNA DSBs, as well as reductions in development to the blastocyst stage and total embryo cell numbers. Treatment of late-cleaving embryos with TUDCA mitigated these effects and markedly improved embryo quality and development. These results demonstrate the importance of stress coping responses in early developing embryos, and that reduction of ER stress is a potential means to improve embryo quality and developmental competence.

Phospholipase C zeta and calcium oscillations at fertilisation: The evidence, applications, and further questions

Oocyte activation is a fundamental event at mammalian fertilisation, initiated by a series of characteristic calcium (Ca²⁺) oscillations in mammals. This characteristic pattern of Ca²⁺ release is induced in a species-specific manner by a sperm-specific enzyme termed phospholipase C zeta (PLCζ). Reduction or absence of functional PLCζ within sperm underlies male factor infertility in humans, due to mutational inactivation or abrogation of PLCζ protein expression. Underlying such clinical implications, a significant body of evidence has now been accumulated that has characterised the unique biochemical and biophysical properties of this enzyme, further aiding the unique clinical opportunities presented. Herein, we present and discuss evidence accrued over the past decade and a half that serves to support the identity of PLCζ as the mammalian sperm factor. Furthermore, we also discuss the potential novel avenues that have yet to be examined regarding PLCζ mechanism of action in both the oocyte, and the sperm. Finally, we discuss the advances that have been made regarding the clinical therapeutic and diagnostic applications of PLCζ in potentially treating male infertility as a result of oocyte activation deficiency (OAD), and also possibly more general cases of male subfertility.

Meta-analysis identifies candidate key genes in endometrium as predictive biomarkers for clinical pregnancy in IVF

Genetic factors in endometrium are likely to be involved in the embryo implantation failure (IF), one of the major limiting factors in the success of in vitro fertilization (IVF). In this study, we aimed to identify critical genes from the transcriptional profile for the establishment of the endometrial receptivity which supporting the normal pregnancy. Three GEO datasets, including 12 samples of IF and 12 samples of controls, were used for the meta-analysis. We identified 182 different expression genes (DEGs) by comparing IF with controls and present here the successful clustering according to sample type, not by the origin. The gene ontology (GO) enriched analysis demonstrated the significant downregulation in activation and regulation of inflammatory and immune response in IF patients. Furthermore, network analysis of down-regulated genes identified the significant hub genes containing GADD45A (growth arrest and DNA damage inducible alpha, Degree = 77), GZMB (granzyme B, Degree = 38) and NLRP2 (NLR family pyrin domain containing 2, Degree = 37). The lower expression of NLRP2, related to inflammatory responses with the most degree in the network, was validatied by other GEO data. Besides, it was confirmed that the NLRP2 could act as a predictor for pregnancy after IVF (AUC = 87.93%; sensitivity, 60.00%; specificity, 91.30% ). Our meta-analysis will help us to better understand the molecular regulation of endometrial receptivity, and guiding further line of treatment for IF during IVF.

The role and mechanism of action of sperm PLC-zeta in mammalian fertilisation

At mammalian fertilisation, the fundamental stimulus that triggers oocyte (egg) activation and initiation of early embryonic development is an acute rise of the intracellular-free calcium (Ca²⁺) concentration inside the egg cytoplasm. This essential Ca²⁺ increase comprises a characteristic series of repetitive Ca²⁺ oscillations, starting soon after sperm-egg fusion. Over the last 15 years, accumulating scientific and clinical evidence supports the notion that the physiological stimulus that precedes the cytosolic Ca²⁺ oscillations is a novel, testis-specific phospholipase C (PLC) isoform, known as PLC-zeta (PLCζ). Sperm PLCζ catalyses the hydrolysis of phosphatidylinositol 4,5-bisphosphate triggering cytosolic Ca²⁺ oscillations through the inositol 1,4,5-trisphosphate signalling pathway. PLCζ is the smallest known mammalian PLC isoform with the most elementary domain organisation. However, relative to somatic PLCs, the PLCζ isoform possesses a unique potency in stimulating Ca²⁺ oscillations in eggs that is attributed to its novel biochemical characteristics. In this review, we discuss the latest developments that have begun to unravel the vital role of PLCζ at mammalian fertilisation and decipher its unique mechanism of action within the fertilising egg. We also postulate the significant potential diagnostic and therapeutic capacity of PLCζ in alleviating certain types of male infertility.

Dynamics of cytoplasm and cleavage divisions correlates with preimplantation embryo development

In vitro fertilization has become increasingly popular as an infertility treatment. In order to improve efficiency of this procedure, there is a strong need for a refinement of existing embryo assessment methods and development of novel, robust and non-invasive selection protocols. Studies conducted on animal models can be extremely helpful here, as they allow for more extensive research on the potential biomarkers of embryo quality. In the present paper, we subjected mouse embryos to non-invasive time-lapse imaging and combined the Particle Image Velocimetry analysis of cytoplasmic dynamics in freshly fertilized oocytes with the morphokinetic analysis of recordings covering 5 days of preimplantation development. Our results indicate that parameters describing cytoplasmic dynamics and cleavage divisions independently correspond to mouse embryo's capacity to form a high-quality blastocyst. We also showed for the first time that these parameters are associated with the percentage of abnormal embryonic cells with fragmented nuclei and with embryo's ability to form primitive endoderm, one of the cell lineages differentiated during preimplantation development. Finally, we present a model that links selected cytoplasmic and morphokinetic parameters reflecting frequency of fertilization-induced Ca²⁺-oscillations and timing of 4-cell stage and compaction with viability of the embryo assessed as the total number of cells at the end of its preimplantation development. Our results indicate that a combined analysis of cytoplasmic dynamics and morphokinetics may facilitate the assessment of embryo's ability to form high-quality blastocysts.

Genome editing reveals a role for OCT4 in human embryogenesis

Despite their fundamental biological and clinical importance, the molecular mechanisms that regulate the first cell fate decisions in the human embryo are not well understood. Here we use CRISPR-Cas9-mediated genome editing to investigate the function of the pluripotency transcription factor OCT4 during human embryogenesis. We identified an efficient OCT4-targeting guide RNA using an inducible human embryonic stem cell-based system and microinjection of mouse zygotes. Using these refined methods, we efficiently and specifically targeted the gene encoding OCT4 (POU5F1) in diploid human zygotes and found that blastocyst development was compromised. Transcriptomics analysis revealed that, in POU5F1-null cells, gene expression was downregulated not only for extra-embryonic trophectoderm genes, such as CDX2, but also for regulators of the pluripotent epiblast, including NANOG. By contrast, Pou5f1-null mouse embryos maintained the expression of orthologous genes, and blastocyst development was established, but maintenance was compromised. We conclude that CRISPR-Cas9-mediated genome editing is a powerful method for investigating gene function in the context of human development.

Host genes regulate transcription of sperm-introduced hepatitis B virus genes in embryo

Hepatitis B virus (HBV) can invade the male germline, and sperm-introduced HBV genes could be transcribed in embryo. This study was to explore whether viral gene transcription is regulated by host genes. Embryos were produced by in vitro fertilization of hamster oocytes with human sperm containing the HBV genome. Total RNA extracted from test and control embryos were subjected to SMART-PCR, SSH, microarray hybridization, sequencing and BLAST analysis. Twenty-nine sequences showing significant identity to five human gene families were identified, with CSH2, EIF4G2, PCBD2, PSG4 and TTN selected to represent target genes. Using qRT-PCR, when CSH2 and PCBD2 (or EIF4G2, PSG4 and TTN) were silenced by RNAi, transcriptional levels of HBV s and x genes decreased (or increased). This is the first report that host genes participate in regulation of sperm-introduced HBV gene transcription in embryo, which is critical to prevent negative impact of HBV infection on early embryonic development.

Determinants of The Grade A Embryos in Infertile Women; Zero-Inflated Regression Model

OBJECTIVES

In assisted reproductive technology, it is important to choose high quality embryos for embryo transfer. The aim of the present study was to determine the grade A embryo count and factors related to it in infertile women.

MATERIALS AND METHODS

This historical cohort study included 996 infertile women. The main outcome was the number of grade A embryos. Zero-Inflated Poisson (ZIP) regression and Zero-Inflated Negative Binomial (ZINB) regression were used to model the count data as it contained excessive zeros. Stata software, version 13 (Stata Corp, College Station, TX, USA) was used for all statistical analyses.

RESULTS

After adjusting for potential confounders, results from the ZINB model show that for each unit increase in the number 2 pronuclear (2PN) zygotes, we get an increase of 1.45 times as incidence rate ratio (95% confidence interval (CI): 1.23-1.69, P=0.001) in the expected grade A embryo count number, and for each increase in the cleavage day we get a decrease 0.35 times (95% CI: 0.20-0.61, P=0.001) in expected grade A embryo count.

CONCLUSIONS

There is a significant association between both the number of 2PN zygotes and cleavage day with the number of grade A embryos in both ZINB and ZIP regression models. The estimated coefficients are more plausible than values found in earlier studies using less relevant models.

National survey on use of time-lapse imaging systems in IVF laboratories

PURPOSE

Several time-lapse imaging (TLI) systems for non-invasive continuous monitoring of developing embryos are currently available. The present study explored the prevalence, means of acquisition, and clinical application of TLI systems in USA in vitro fertilization (IVF) laboratories.

METHODS

An online cross-sectional survey of 294 USA IVF laboratory directors was conducted in February and March 2016. Those directing more than one laboratory were asked to complete the survey for their home program and for their smallest laboratory by number of IVF/intracytoplasmic sperm injection (ICSI) cycle starts. Use of TLI was analyzed using logistic regression to calculate odds ratios (OR).

RESULTS

Of 294 directors surveyed, 162 (55%) reported data on 204 laboratories. Thirty-five laboratories (17%) possessed at least one TLI system (median 2, interquartile range 1-4, total range 1-11). The more oocyte retrievals a laboratory performed annually, the more likely the laboratory was to possess a TLI system. Fifteen laboratories (43%) purchased their own systems, while others leased, loaned, or received donated systems. Twenty-five laboratories (71%) reported using TLI for embryo selection; all used TLI always, or usually, in combination with standard morphology evaluation. Twenty laboratories (80%) offered TLI to all patients. Some laboratories charged patients for TLI. Directors with TLI systems were more inclined to believe that TLI has value for embryo selection in clinical IVF.

CONCLUSIONS

TLI system possession in USA IVF laboratories is low, although positively associated with the number of retrievals performed and with directors' opinions on the technology's utility. Over 70% of laboratories with TLI systems use them clinically, and less than half purchased their systems.

Selecting embryos with the highest implantation potential using data mining and decision tree based on classical embryo morphology and morphokinetics

PURPOSE

The objective of this work was to determine which embryonic morphokinetic parameters up to D3 of in vitro development have predictive value for implantation for the selection of embryos for transfer in clinical practice based upon information generated from embryo transfers with known implantation data (KID).

METHODS

A total of 800 KID embryos (100% implantation rate (IR) per transfer and 0% IR per transfer) cultured in an incubator with Time-Lapse system were retrospectively analysed. Of them, 140 embryos implanted, whereas 660 did not.

RESULTS

The analysis of morphokinetic parameters, together with the embryo morphology assessment on D3, enabled us to develop a hierarchical model that places the classical morphological score, the t4 and t8 morphokinetic values, as the variables with the best prognosis of implantation.

CONCLUSION

In our decision tree, the classical morphological score is the most predictive parameter. Among embryos with better morphological scores, morphokinetics permits deselection of embryos with the lowest implantation potential.