Endometrial microbiota composition is associated with reproductive outcome in infertile patients

BACKGROUND

Previous evidence indicates associations between the female reproductive tract microbiome composition and reproductive outcome in infertile patients undergoing assisted reproduction. We aimed to determine whether the endometrial microbiota composition is associated with reproductive outcomes of live birth, biochemical pregnancy, clinical miscarriage or no pregnancy.

METHODS

Here, we present a multicentre prospective observational study using 16S rRNA gene sequencing to analyse endometrial fluid and biopsy samples before embryo transfer in a cohort of 342 infertile patients asymptomatic for infection undergoing assisted reproductive treatments.

RESULTS

A dysbiotic endometrial microbiota profile composed of Atopobium, Bifidobacterium, Chryseobacterium, Gardnerella, Haemophilus, Klebsiella, Neisseria, Staphylococcus and Streptococcus was associated with unsuccessful outcomes. In contrast, Lactobacillus was consistently enriched in patients with live birth outcomes.

CONCLUSIONS

Our findings indicate that endometrial microbiota composition before embryo transfer is a useful biomarker to predict reproductive outcome, offering an opportunity to further improve diagnosis and treatment strategies. Video Abstract.

O-126 Endometrial microbiota composition is associated with reproductive outcome in infertile patients

Study question

Is there an association between the composition of the endometrial microbiota and the reproductive outcomes in infertile patients undergoing in vitro fertilization (IVF)?

Summary answer

The composition of the endometrial microbiota (EM) prior to embryo transfer is associated with the different reproductive outcomes: live birth, no pregnancy or clinical miscarriage.

What is known already

The investigation of bacterial communities in the female reproductive tract using molecular methods has revealed the existence of a continuum microbiota that extends from the vagina to the upper genital tract.

Previous evidence suggests the existence of an association between the vaginal and endometrial microbiome composition with reproductive and obstetrical outcomes. Specifically, the presence of specific pathogens together with low abundance of Lactobacilli has been associated with poor IVF outcomes.

Study design, size, duration

Multicentre prospective observational clinical study analysing the EM of infertile patients undergoing IVF (with maternal age ≤40) or ovum donation (≤50 years). A total of 452 infertile patients undergoing IVF/ovum donation were assessed for eligibility in 13 reproductive clinics in Europe, America, and Asia. The duration of the study was 30 months and the recruitment period extended between August 2017 and February 2019 (ct.gov 03330444).

Participants/materials, setting, methods

Endometrial fluid and endometrial biopsy were collected during a hormonal replacement therapy cycle after 5 days of progesterone (P) administration prior to a frozen embryo transfer cycle. Endometrial microbiota (EM) composition was analyzed using 16S rRNA gene sequencing using compositional data to transform scale-invariant values in both sample types. The EM in fluid and biopsy was associated with live birth, biochemical pregnancy, clinical miscarriage, or no pregnancy.

Main results and the role of chance

Of the 452 patients assessed, 44 did not meet the selection criteria and were excluded for the study and 66 patients were lost to follow-up. Of the 342 remaining patients, 198 (57.9%) became pregnant [141 (41.2%) had a live birth, 27 (7.9%) had a biochemical pregnancy, 2 (0.6%) had an ectopic pregnancy, and 28 (8.2%) a clinical miscarriage], while 144 (42.1%) did not become pregnant. The baseline characteristics, clinical and embryological variables were homogeneous and no bias toward the clinical outcome categories was observed.

Our association study showed that the composition of the EM was associated with the reproductive outcome in both endometrial fluid and biopsy. A dysbiotic endometrial microbiota profile composed of Atopobium, Bifidobacterium, Chryseobacterium, Gardnerella, Haemophilus, Klebsiella, Neisseria, Staphylococcus and Streptococcus was significantly associated with unsuccessful outcomes, especially no pregnancy and clinical miscarriage. In contrast, Lactobacillus was consistently enriched in patients with live birth outcomes. The EM in endometrial fluid did not fully reflect that in endometrial biopsy, although their association with clinical outcome was consistent.

Limitations, reasons for caution

The main limitation was the small number of biochemical pregnancy and clinical miscarriage analysed. During transcervical collection of endometrial samples caution was taken to avoid contamination with the cervix although cervical contamination cannot be fully discarded.

Wider implications of the findings

Our data indicate that EM dysbiosis is associated with poor clinical outcome in ART. Thus, the EM composition before embryo transfer could be a useful biomarker to consider offering an opportunity to further improve diagnosis and treatment strategies.

Trial registration number

Clinical trials.gov 03330444

Obesity Affects Endometrial Receptivity by Displacing the Window of Implantation

Our aim was to determine prospectively whether increased body mass index (BMI) affects endometrial receptivity through displacement of the window of implantation (dWOI) using the endometrial receptivity analysis (ERA), and whether this effect is BMI-dependent. We recruited a population of 170 infertile women with a normal uterus and no clinical history of recurrent miscarriage or implantation failure. These women were divided into four groups according to BMI: normal weight (18.5-24.9 kg/m²; n = 44), overweight (25-29.9 kg/m²; n = 29), class I obese (30.0-34.9 kg/m²; n = 54), and class II and III obese (> 35 kg/m²; n = 43). We also assigned the patients to one of two larger BMI cohorts: non-obese (normal weight and overweight; n = 73) and obese (class I, II, and III obese; n = 97). We compared analytical and clinical data and dWOI in these categories, finding significant metabolic differences in glycemia, TSH, insulin, HDL cholesterol, LDL cholesterol, triglycerides, and systolic and diastolic blood pressure among the different BMI groups. One-day dWOI increased significantly with BMI, and significant differences were observed in the non-obese versus obese categories (9.7% vs 25.3 %, respectively (p = 0.02)). dWOI was most pronounced in patients with class II-III obesity. In addition, displacement was longer as BMI increased since ERA revealed a higher proportion of displacements of 1 day than of 12 h and showed they were predominantly pre-receptive. In conclusion, obesity has a negative effect on endometrial receptivity through delaying of the WOI, which increases in function of BMI as well as the metabolic disturbances of the patient.

Endometrial Receptivity Analysis (ERA): data versus opinions

This article summarises and contextualises the accumulated basic and clinical data on the ERA test and addresses specific comments and opinions presented by the opponent as part of an invited debate. Progress in medicine depends on new technologies and concepts that translate to practice to solve long-standing problems. In a key example, combining RNA sequencing data (transcriptomics) with artificial intelligence (AI) led to a clinical revolution in personalising disease diagnosis and fostered the concept of precision medicine. The reproductive field is no exception. Translation of endometrial transcriptomics to the clinic yielded an objective definition of the limited time period during which the maternal endometrium is receptive to an embryo, known as the window of implantation (WOI). The WOI is induced by the presence of exogenous and/or endogenous progesterone (P) after proper oestradiol (E2) priming. The window lasts 30-36 hours and, depending on the patient, occurs between LH + 6 and LH + 9 in natural cycles or between P + 4 and P + 7 in hormonal replacement therapy (HRT) cycles. In approximately 30% of IVF cycles in which embryo transfer is performed blindly, the WOI is displaced and embryo-endometrial synchrony is not achieved. Extending this application of endometrial transcriptomics, the endometrial receptivity analysis (ERA) test couples next-generation sequencing (NGS) to a computational predictor to identify transcriptomic signatures for each endometrial stage: proliferative (PRO), pre-receptive (PRE), receptive (R) and post-receptive (POST). In this way, personalised embryo transfer (pET) may be possible by synchronising embryo transfer with each patient's WOI. Data are the only way to confront arguments sustained in opinions and/or misleading concepts; it is up to the reader to make their own conclusions regarding its clinical utility.

Multicenter prospective study of concordance between embryonic cell-free DNA and trophectoderm biopsies from 1301 human blastocysts

BACKGROUND

The recent identification of embryonic cell-free DNA in spent blastocyst media has opened a new era of possibilities for noninvasive embryo aneuploidy testing in assisted reproductive technologies. Yet, previous studies assessing a limited number of embryos reported variable concordance between embryonic cell-free DNA and trophectoderm biopsies, thus questioning the validity of this approach.

OBJECTIVE

This study aimed to evaluate the concordance and reproducibility of testing embryonic cell-free DNA vs trophectoderm DNA obtained from the same embryo in a large sample of human blastocysts and to assess the contribution of the inner cell mass and trophectoderm to embryonic cell-free DNA released to the culture media.

STUDY DESIGN

This is an interim analysis of a prospective, observational study among 8 in vitro fertilization centers in 4 continents to assess consistency between noninvasive embryo aneuploidy testing of embryonic cell-free DNA and conventional trophectoderm biopsy. The analysis included 1301 day-6/7 blastocysts obtained in 406 in vitro fertilization cycles from 371 patients aged 20-44 years undergoing preimplantation genetic testing for aneuploidy. Fresh oocytes underwent intracytoplasmic sperm injection or in vitro fertilization. No previous assisted hatching or vitrification was allowed before media collection. Individual spent blastocyst medium was collected from embryos cultured at least 40 hours from day 4. After media collection, conventional preimplantation genetic testing for aneuploidy, comprising trophectoderm biopsy and blastocyst vitrification, was performed. Embryonic cell-free DNA was analyzed blindly after embryo transfer. Inner cell mass and trophectoderm biopsies were also performed in a subset of 81 aneuploid blastocysts donated for research.

RESULTS

Embryonic cell-free DNA analyses were 78.2% (866/1108) concordant with the corresponding trophectoderm biopsies. No significant differences were detected among centers ranging from 72.5% to 86.3%. Concordance rates exceeded 86% when all defined steps in the culture laboratory were controlled to minimize the impact of maternal and operator contamination. Sensitivity per center ranged from 76.5% to 91.3% and specificity from 64.7% to 93.3%. The false-negative rate was 8.3% (92/1108), and false-positive rate was 12.4% (137/1108). The 2 fertilization techniques provided similar sensitivity (80.9% vs 87.9%) and specificity (78.6% vs 69.9%). Multivariate analysis did not reveal any bias from patient clinical background, ovarian stimulation protocols, culture conditions, or embryo quality on testing accuracy of concordance. Moreover, concordances of embryonic cell-free DNA with trophectoderm and inner cell mass suggest that the embryonic cell-free DNA originates from both compartments of the human embryo.

CONCLUSION

Noninvasive analysis of embryonic cell-free DNA in spent blastocyst culture media demonstrates high concordance with trophectoderm biopsy results in this large multicenter series. A noninvasive approach for prioritizing embryo euploidy offers important advantages such as avoiding invasive embryo biopsy and decreased cost, potentially increasing accessibility for a wider patient population.

Embryonic cell-free DNA versus trophectoderm biopsy for aneuploidy testing: concordance rate and clinical implications

OBJECTIVE

To study whether embryonic cell-free DNA (cfDNA) in spent blastocyst media is representative of the chromosomal constitution of a blastocyst.

DESIGN

Pilot prospective blinded study.

SETTING

In vitro fertilization center and genetics laboratory.

PATIENT(S)

A total of 115 trophectoderm (TE) biopsies and spent blastocyst media (SBM) from 46 patients with ages ranging from 32 to 46 years, whose indications for preimplantation genetic testing of aneuploidy (PGT-A) were advanced maternal age, recurrent miscarriage, or recurrent implantation failure.

INTERVENTIONS(S)

Spent blastocyst media collection and TE biopsy.

MAIN OUTCOME MEASURE(S)

Concordance rates, sensitivity, and specificity between TE biopsies and SBM. Clinical outcomes in cases with euploid TE biopsies and euploid SBM compared with cases with euploid TE and aneuploid SBM.

RESULT(S)

In general, the total concordance rate for ploidy and sex was 78.7%, and sensitivity and specificity were 94.5% and 71.7%, respectively. A significant increase for all parameters was observed for day 6/7 samples compared with day 5 samples, with day 6/7 samples showing total concordance for ploidy and sex of 84%, and sensitivity and specificity of 95.2% and 82.1%, respectively. Ongoing implantation rates in euploid TE/euploid SBM showed a threefold increase compared with euploid TE/aneuploid SBM (52.9% vs. 16.7%, respectively), without reaching significant differences. Interestingly, no miscarriages were observed when TE and SBM were euploidy concordant.

CONCLUSION(S)

These results offer a better understanding of the dynamics of cfDNA during embryo development and despite more basic research being needed, they are reassuring to consider in the future this noninvasive approach as an alternative to TE biopsy for PGT-A.

Origin and composition of cell-free DNA in spent medium from human embryo culture during preimplantation development

STUDY QUESTION

What is the origin and composition of cell-free DNA in human embryo spent culture media?

SUMMARY ANSWER

Cell-free DNA from human embryo spent culture media represents a mix of maternal and embryonic DNA, and the mixture can be more complex for mosaic embryos.

WHAT IS KNOWN ALREADY

In 2016, ~300 000 human embryos were chromosomally and/or genetically analyzed using preimplantation genetic testing for aneuploidies (PGT-A) or monogenic disorders (PGT-M) before transfer into the uterus. While progress in genetic techniques has enabled analysis of the full karyotype in a single cell with high sensitivity and specificity, these approaches still require an embryo biopsy. Thus, non-invasive techniques are sought as an alternative.

STUDY DESIGN, SIZE, DURATION

This study was based on a total of 113 human embryos undergoing trophectoderm biopsy as part of PGT-A analysis. For each embryo, the spent culture media used between Day 3 and Day 5 of development were collected for cell-free DNA analysis. In addition to the 113 spent culture media samples, 28 media drops without embryo contact were cultured in parallel under the same conditions to use as controls. In total, 141 media samples were collected and divided into two groups: one for direct DNA quantification (53 spent culture media and 17 controls), the other for whole-genome amplification (60 spent culture media and 11 controls) and subsequent quantification. Some samples with amplified DNA (N = 56) were used for aneuploidy testing by next-generation sequencing; of those, 35 samples underwent single-nucleotide polymorphism (SNP) sequencing to detect maternal contamination. Finally, from the 35 spent culture media analyzed by SNP sequencing, 12 whole blastocysts were analyzed by fluorescence in situ hybridization (FISH) to determine the level of mosaicism in each embryo, as a possible origin for discordance between sample types.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Trophectoderm biopsies and culture media samples (20 μl) underwent whole-genome amplification, then libraries were generated and sequenced for an aneuploidy study. For SNP sequencing, triads including trophectoderm DNA, cell-free DNA, and follicular fluid DNA were analyzed. In total, 124 SNPs were included with 90 SNPs distributed among all autosomes and 34 SNPs located on chromosome Y. Finally, 12 whole blastocysts were fixed and individual cells were analyzed by FISH using telomeric/centromeric probes for the affected chromosomes.

MAIN RESULTS AND THE ROLE OF CHANCE

We found a higher quantity of cell-free DNA in spent culture media co-cultured with embryos versus control media samples (P ≤ 0.001). The presence of cell-free DNA in the spent culture media enabled a chromosomal diagnosis, although results differed from those of trophectoderm biopsy analysis in most cases (67%). Discordant results were mainly attributable to a high percentage of maternal DNA in the spent culture media, with a median percentage of embryonic DNA estimated at 8%. Finally, from the discordant cases, 91.7% of whole blastocysts analyzed by FISH were mosaic and 75% of the analyzed chromosomes were concordant with the trophectoderm DNA diagnosis instead of the cell-free DNA result.

LIMITATIONS, REASONS FOR CAUTION

This study was limited by the sample size and the number of cells analyzed by FISH.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study to combine chromosomal analysis of cell-free DNA, SNP sequencing to identify maternal contamination, and whole-blastocyst analysis for detecting mosaicism. Our results provide a better understanding of the origin of cell-free DNA in spent culture media, offering an important step toward developing future non-invasive karyotyping that must rely on the specific identification of DNA released from human embryos.

STUDY FUNDING/ COMPETING INTEREST

This work was funded by Igenomix S.L. There are no competing interests.

Introduction: Endometrial function: facts, urban legends, and an eye to the future

The embryo alone, though very important, is not sufficient to explain successful or failed implantation. Human embryonic implantation is less efficient than in nonmenstruating species. The main difference lies in the decidual control of early implantation events and the subsequent course of pregnancy versus embryo control in nonmenstruating species. In this article, we introduce the facts behind the low efficiency of this crucial process, address urban legends routinely considered without high clinical quality evidence, and provide a vision of how the endometrial field will develop in the near future.

Does an increased body mass index affect endometrial gene expression patterns in infertile patients? A functional genomics analysis

OBJECTIVE

To analyze the transcriptomic profile of endometrial gene alterations during the window of implantation in infertile obese patients.

DESIGN

Multicenter, prospective, case-control study.

SETTING

Three academic medical centers for reproductive medicine.

PATIENT(S)

Infertile patients, stratified into body mass index (BMI) categories according to the World Health Organization guidelines, were included in the study.

INTERVENTION(S)

Endometrial samples were obtained from women undergoing standardized estrogen and P replacement cycles after 5 days of vaginal P supplementation.

MAIN OUTCOME MEASURE(S)

To identify endometrial gene expression alterations that occur during the window of implantation in infertile obese patients as compared with infertile normal-weight controls using a microarray analysis.

RESULT(S)

XCL1, XCL2, HMHA1, S100A1, KLRC1, COTL1, COL16A1, KRT7, and MFAP5 are significantly dysregulated during the window of implantation in the receptive endometrium of obese patients. COL16A1, COTL1, HMHA1, KRCL1, XCL1, and XCL2 were down-regulated and KRT7, MFAP5, and S100A1 were up-regulated in the endometrium of obese patients. These genes are mainly involved in chemokine, cytokine, and immune system activity and in the structural extracellular matrix and protein-binding molecular functions.

CONCLUSION(S)

Obesity is associated with significant endometrial transcriptomic differences as compared with non-obese subjects. Altered endometrial gene expression in obese patients may contribute to the lower implantation rates and increased miscarriage rates seen in obese infertile patients.

CLINICAL TRIAL REGISTRATION NUMBER

NCT02205866.

Evidence that the endometrial microbiota has an effect on implantation success or failure

BACKGROUND

Bacterial cells in the human body account for 1-3% of total body weight and are at least equal in number to human cells. Recent research has focused on understanding how the different bacterial communities in the body (eg, gut, respiratory, skin, and vaginal microbiomes) predispose to health and disease. The microbiota of the reproductive tract has been inferred from the vaginal bacterial communities, and the uterus has been classically considered a sterile cavity. However, while the vaginal microbiota has been investigated in depth, there is a paucity of consistent data regarding the existence of an endometrial microbiota and its possible impact in reproductive function.

OBJECTIVE

This study sought to test the existence of an endometrial microbiota that differs from that in the vagina, assess its hormonal regulation, and analyze the impact of the endometrial microbial community on reproductive outcome in infertile patients undergoing in vitro fertilization.

STUDY DESIGN

To identify the existence of an endometrial microbiota, paired samples of endometrial fluid and vaginal aspirates were obtained simultaneously from 13 fertile women in prereceptive and receptive phases within the same menstrual cycle (total samples analyzed n = 52). To investigate the hormonal regulation of the endometrial microbiota during the acquisition of endometrial receptivity, endometrial fluid was collected at prereceptive and receptive phases within the same cycle from 22 fertile women (n = 44). Finally, the reproductive impact of an altered endometrial microbiota in endometrial fluid was assessed by implantation, ongoing pregnancy, and live birth rates in 35 infertile patients undergoing in vitro fertilization (total samples n = 41) with a receptive endometrium diagnosed using the endometrial receptivity array. Genomic DNA was obtained either from endometrial fluid or vaginal aspirate and sequenced by 454 pyrosequencing of the V3-V5 region of the 16S ribosomal RNA (rRNA) gene; the resulting sequences were taxonomically assigned using QIIME. Data analysis was performed using R packages. The χ² test, Student t test, and analysis of variance were used for statistical analyses.

RESULTS

When bacterial communities from paired endometrial fluid and vaginal aspirate samples within the same subjects were interrogated, different bacterial communities were detected between the uterine cavity and the vagina of some subjects. Based on its composition, the microbiota in the endometrial fluid, comprising up to 191 operational taxonomic units, was defined as a Lactobacillus-dominated microbiota (>90% Lactobacillus spp.) or a non-Lactobacillus-dominated microbiota (<90% Lactobacillus spp. with >10% of other bacteria). Although the endometrial microbiota was not hormonally regulated during the acquisition of endometrial receptivity, the presence of a non-Lactobacillus-dominated microbiota in a receptive endometrium was associated with significant decreases in implantation [60.7% vs 23.1% (P = .02)], pregnancy [70.6% vs 33.3% (P = .03)], ongoing pregnancy [58.8% vs 13.3% (P = .02)], and live birth [58.8% vs 6.7% (P = .002)] rates.

CONCLUSION

Our results demonstrate the existence of an endometrial microbiota that is highly stable during the acquisition of endometrial receptivity. However, pathological modification of its profile is associated with poor reproductive outcomes for in vitro fertilization patients. This finding adds a novel microbiological dimension to the reproductive process.

Human stem cells from single blastomeres reveal pathways of embryonic or trophoblast fate specification

Mechanisms of initial cell fate decisions differ among species. To gain insights into lineage allocation in humans, we derived ten human embryonic stem cell lines (designated UCSFB1-10) from single blastomeres of four 8-cell embryos and one 12-cell embryo from a single couple. Compared with numerous conventional lines from blastocysts, they had unique gene expression and DNA methylation patterns that were, in part, indicative of trophoblast competence. At a transcriptional level, UCSFB lines from different embryos were often more closely related than those from the same embryo. As predicted by the transcriptomic data, immunolocalization of EOMES, T brachyury, GDF15 and active β-catenin revealed differential expression among blastomeres of 8- to 10-cell human embryos. The UCSFB lines formed derivatives of the three germ layers and CDX2-positive progeny, from which we derived the first human trophoblast stem cell line. Our data suggest heterogeneity among early-stage blastomeres and that the UCSFB lines have unique properties, indicative of a more immature state than conventional lines.

Mitochondrial DNA content as a viability score in human euploid embryos: less is better

OBJECTIVE

To investigate the clinical relevance of mitochondrial DNA (mtDNA) content as a viability score in human euploid embryos.

DESIGN

Retrospective analysis of mtDNA content of transferred euploid embryos.

SETTING

Reproductive genetics laboratory.

PATIENT(S)

Single-embryo transfer in 270 patients who underwent preimplantation genetic screening (205 day-3 blastomere biopsies, and 65 day-5 trophectoderm biopsies), and 10 patients with double-embryo transfer (male-female).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Normalized mtDNA content versus nuclear DNA (nDNA) from transferred euploid embryos.

RESULT(S)

A high mtDNA copy number in euploid embryos is indicative of lower embryo viability and implantation. Using the normalized mtDNA content, we created the mitochondrial score or Mitoscore (Ms). Day-3 embryos with <34 (MsA) had an implantation rate (IR) of 59% (n = 51); those with 34-52 (MsB) had an IR of 44% (n = 52); those with 52-97 (MsC) had an IR of 42% (n = 50); and those with >97 (MsD) had an IR of 25% (n = 52). Embryos with Ms >160 (n = 22) never implanted. Day-5 embryos with <18.19 (MsA) had an IR of 81%; those with 18.19-24.15 (MsB) had an IR of 50% (n = 16); those with 24.15-50.58 (MsC) had an IR of 62% (n = 16); and those with levels >50.58 (MsD) had an IR of 18% (n = 17). Embryos with levels >60 (n = 7) never implanted.

CONCLUSION(S)

An increased amount of mtDNA in euploid embryos is related to poor implantation potential and may be indicative of reduced metabolic fuel during oocyte maturation. We are implementing Ms in our preimplantation genetic screening platform to prospectively analyze its clinical relevance.

Asynchronous BCI based on motor imagery with automated calibration and neurofeedback training

A new multiclass brain-computer interface (BCI) based on the modulation of sensorimotor oscillations by imagining movements is described. By the application of advanced signal processing tools, statistics and machine learning, this BCI system offers: 1) asynchronous mode of operation, 2) automatic selection of user-dependent parameters based on an initial calibration, 3) incremental update of the classifier parameters from feedback data. The signal classification uses spatially filtered signals and is based on spectral power estimation computed in individualized frequency bands, which are automatically identified by a specially tailored AR-based model. Relevant features are chosen by a criterion based on Mutual Information. Final recognition of motor imagery is effectuated by a multinomial logistic regression classifier. This BCI system was evaluated in two studies. In the first study, five participants trained the ability to imagine movements of the right hand, left hand and feet in response to visual cues. The accuracy of the classifier was evaluated across four training sessions with feedback. The second study assessed the information transfer rate (ITR) of the BCI in an asynchronous application. The subjects' task was to navigate a cursor along a computer rendered 2-D maze. A peak information transfer rate of 8.0 bit/min was achieved. Five subjects performed with a mean ITR of 4.5 bit/min and an accuracy of 74.84%. These results demonstrate that the use of automated interfaces to reduce complexity for the intended operator (outside the laboratory) is indeed possible. The signal processing and classifier source code embedded in BCI2000 is available from https://www.brain-project.org/downloads.html.

BCI demographics II: how many (and what kinds of) people can use a high-frequency SSVEP BCI?

Brain-computer interface (BCI) systems use brain activity as an input signal and enable communication without movement. This study is a successor of our previous study (BCI demographics I) and examines correlations among BCI performance, personal preferences, and different subject factors such as age or gender for two sets of steady-state visual evoked potential (SSVEP) stimuli: one in the medium frequency range (13, 14, 15 and 16 Hz) and another in the high-frequency range (34, 36, 38, 40 Hz). High-frequency SSVEPs (above 30 Hz) diminish user fatigue and risk of photosensitive epileptic seizures. Results showed that most people, despite having no prior BCI experience, could use the SSVEP-based Bremen-BCI system in a very noisy field setting at a fair. Results showed that demographic parameters as well as handedness, tiredness, alcohol and caffeine consumption, etc., have no significant effect on the performance of SSVEP-based BCI. Most subjects did not consider the flickering stimuli annoying, only five out of total 86 participants indicated change in fatigue during the experiment. 84 subjects performed with a mean information transfer rate of 17.24 ±6.99 bit/min and an accuracy of 92.26 ±7.82% with the medium frequency set, whereas only 56 subjects performed with a mean information transfer rate of 12.10 ±7.31 bit/min and accuracy of 89.16 ±9.29% with the high-frequency set. These and other demographic analyses may help identify the best BCI for each user.

Functional genomics of 5- to 8-cell stage human embryos by blastomere single-cell cDNA analysis

Blastomere fate and embryonic genome activation (EGA) during human embryonic development are unsolved areas of high scientific and clinical interest. Forty-nine blastomeres from 5- to 8-cell human embryos have been investigated following an efficient single-cell cDNA amplification protocol to provide a template for high-density microarray analysis. The previously described markers, characteristic of Inner Cell Mass (ICM) (n = 120), stemness (n = 190) and Trophectoderm (TE) (n = 45), were analyzed, and a housekeeping pattern of 46 genes was established. All the human blastomeres from the 5- to 8-cell stage embryo displayed a common gene expression pattern corresponding to ICM markers (e.g., DDX3, FOXD3, LEFTY1, MYC, NANOG, POU5F1), stemness (e.g., POU5F1, DNMT3B, GABRB3, SOX2, ZFP42, TERT), and TE markers (e.g., GATA6, EOMES, CDX2, LHCGR). The EGA profile was also investigated between the 5-6- and 8-cell stage embryos, and compared to the blastocyst stage. Known genes (n = 92) such as depleted maternal transcripts (e.g., CCNA1, CCNB1, DPPA2) and embryo-specific activation (e.g., POU5F1, CDH1, DPPA4), as well as novel genes, were confirmed. In summary, the global single-cell cDNA amplification microarray analysis of the 5- to 8-cell stage human embryos reveals that blastomere fate is not committed to ICM or TE. Finally, new EGA features in human embryogenesis are presented.

sBCI: fast detection of steady-state visual evoked potentials

Brain-computer interface (BCI) systems enable communication and control without movement. Although advanced signal processing methods are used in BCI research, the output of a BCI is still unreliable, and the information transfer rates are very low compared with conventional human interaction interfaces such as keyboard and mouse. Therefore, improvements in signal classification methods and the exploitation of the learning skills of the user are required to compensate the unreliability of the BCI system. This work analyzes the response time of the Bremen-BCI based on steady-state visual evoked potentials (SSVEP) previously tested on 27 subjects, and presents an enhanced method for faster detection of SSVEP responses. The aim is toward the development of a swift BCI (sBCI) that robustly detects the exact time point where the user starts modulating his brain signals.

Efficient method for slow cryopreservation of human embryonic stem cells in xeno-free conditions

An effective, consistent and xeno-free cryopreservation technique is crucial for any human embryonic stem cell (hESC) laboratory with future perspectives for clinical application. This study presents a new slow freezing-rapid thawing method in serum-free conditions that allows the cryopreservation of a large number of colonies without the use of a programmable freezer. To test its efficacy, this method has been compared with two established vitrification methods and applied to three different hESC lines (H9, VAL-3 and VAL-5). The method is based on an increasing concentration of dimethylsulphoxide (1.0, 1.2, 1.5 and 2.0 mol/l) with a slow or a rapid cooling system. Using this method, approximately 60 colonies per cryovial could be cryopreserved, the survival rate ranged between 15 and 68% depending on the cell line used, and the majority of the surviving colonies were grade A. Post-cryopreserved hESC have been cultured for 20 passages, re-cryopreserved and re-thawed with consistent results. After thawing, cells retained the inherent undifferentiated characteristics of hESC and growth rate curve, with a stable karyotype, telomerase activity and teratoma formation when injected into severe combined immunodeficient animals, which was comparable with the fresh lines. This method has been tested for 3 years in two different laboratories.

Derivation and characterization of three new Spanish human embryonic stem cell lines (VAL -3 -4 -5) on human feeder and in serum-free conditions

A total of 184 human embryos, frozen for >5 years, were donated; informed consent was obtained according to Spanish law 45/2003. Survival rate was 40% and three out of 24 blastocysts (12.5%) developed into putative hESC lines, named VAL-3, VAL-4, and VAL-5. The derivation process was performed on microbiologically tested and irradiated human foreskin fibroblasts and designed to minimize contact with xeno-components in knockout DMEM supplemented with knockout serum replacement, and basic fibroblast growth factor. Fingerprinting and HLA typing of the cell lines allowed their identification and traceability. Karyotype was normal for VAL-3 (46XY), VAL-4 (46XX) and VAL-5 (46XX). All three hESC lines expressed specific markers for non-differentiation (Nanog, stage-specific embryonic antigen-4 [SSEA-4], tumour-related antigen [TRA]-1-60, and TRA-1-81) and were negative for SSEA-1. RT-PCR further demonstrated the expression of Oct-4, Sox2, Rex-1, Nanog, Cripto, Thy-1, and Lefty-A. Furthermore, they were found to be negative for classical differentiation markers such as neurofilament heavy chain (ectoderm), renin (mesoderm), and amylase (endoderm). All three cell lines displayed high levels of telomerase activity, and were shown to successfully overcome cryopreservation and thawing. Finally, these three new hESC lines have demonstrated the potential to differentiate in vitro and in vivo (teratoma formation) into cell types originating from all three germ layers.

Human Embryo Culture

Human embryonic stem cells (hESCs) are derived from preimplantation embryos. Approximately 60% of human embryos are blocked during in vitro development. Although statistics are inconclusive, experience demonstrates that hESCs are more effectively derived from high-quality embryos. In this way, optimal human embryo culture conditions are a crucial aspect in any derivation laboratory. Embryos can be cultured solely with sequential media or cocultured on a monolayer of a given cell type. This chapter explores general aspects of human embryonic development, the concept of sequential culture and coculture, and specific protocols and procedures in which the authors are experienced, including the results obtained.

Derivation of clinical-grade human embryonic stem cells

Embryonic stem cells proliferate in vitro while maintaining an undifferentiated state, and are capable of differentiating into most cell types under appropriate conditions. These properties imply great potential in the treatment of various diseases and disabilities. In fact, the first clinical trials with hESC for treating spinal cord injuries will begin next year. However, therapeutic application of human embryonic stem cell derivatives is compromised by the exposure of existing lines to animal and human components, with the subsequent risk of contamination with retroviruses and other pathogens, which can be transmitted to patients. The scientific community is striving to avoid the use of xenogeneic or allogeneic components in the process of derivation new hESC lines. This review summarizes attempts that have been made to avoid these contaminants and the breakthroughs achieved in the derivation of clinical-grade hESC that could be used for therapeutic purposes.

First derivation in Spain of human embryonic stem cell lines: Use of long-term cryopreserved embryos and animal-free conditions

The first two human embryonic stem cell lines (VAL-1 and VAL-2) have been derived in Spain with long-term cryopreserved embryos under animal-free conditions. In the first series, 40 human embryos that had been cryopreserved at day 2 of development were thawed after >5 years. A derivation efficiency of 5% per frozen embryo or 12.5% per blastocyst was obtained.

New techniques on embryo manipulation

For many years, experience has been accumulated on embryo and gamete manipulation in livestock animals. The present work is a review of these techniques and their possible application in human embryology in specific cases. It is possible to manipulate gametes at different levels, producing paternal or maternal haploid embryos (hemicloning), using different techniques including nuclear transfer. At the embryonic stage, considering practical, ethical and legal issues, techniques will be reviewed that include cloning and embryo splitting at the cleavage stage, morula, or blastocyst stage.

Increasing levels of estradiol are deleterious to embryonic implantation because they directly affect the embryo

OBJECTIVE

To investigate whether the deleterious effect of E(2) on embryonic implantation is due to a direct effect on the endometrium, on the embryo, or both.

DESIGN

Prospective, controlled in vitro study.

SETTING

Tertiary infertility center.

PATIENT(S)

Fertile patients in the luteal phase with histologically normal endometrium who were attending the infertility clinic as oocyte donors (n = 14).

INTERVENTION(S)

E(2) dose-response (0, 10(-8), 10(-7), 10(-6), 10(-5), and 10(-4) M) and time course (day 2 vs. day 5) experiments were performed in an in vitro embryo adhesion assay composed of human polarized endometrial epithelial cells obtained from fertile patients and mouse embryos.

MAIN OUTCOME MEASURE(S)

Blastocyst formation rate and embryo adhesion rate.

RESULTS

Monolayers of polarized endometrial epithelial cells expressed ERalpha at the mRNA level. The E(2) dose response of blastocysts with polarized endometrial epithelial cells (n = 235) demonstrated a progressive reduction in embryonic adhesion that was statistically significant at 10(-6) M. When polarized endometrial epithelial cells were treated alone with increasing doses of E(2) for 3 days and E(2) was then removed and blastocysts added (n = 410), embryonic adhesion was not significantly reduced, except at 10(-4) M. When 2-day mouse embryos (n = 609) were treated with increasing E(2) concentrations until day 5, the rate of blastocyst formation significantly decreased at a concentration >or= 10(-6) M, and embryonic adhesion decreased when blastocysts (n = 400) were obtained at a concentration >or= 10(-7) M. Time course experiments of embryos cultured for 2 days with polarized endometrial epithelial cells (n = 426) showed that the adhesion rate was higher at E(2) levels of 10(-7), 10(-6) and 10(-5) M compared with embryos cultured for 5 days (n = 495).

CONCLUSION(S)

High E(2) levels are deleterious to embryo adhesion in vitro, mainly because they have a direct toxic effect on the embryo that may occur at the cleavage stage.

The effect of intercourse on pregnancy rates during assisted human reproduction

Intercourse during an IVF cycle has the potential to improve pregnancy rates since exposure to semen is reported to promote embryo development and implantation in animals. Conversely, coitus-induced uterine contractions or introduction of infection may have a detrimental effect. A multicentre prospective randomized control trial was conducted to determine if intercourse during the peri-transfer period of an IVF cycle has any influence on pregnancy success. Participants undergoing thawed embryo transfer (Australian centre) or fresh embryo transfers (Spanish centres) were randomized either to abstain or to engage in vaginal intercourse around the time of embryo transfer. The transfer of 1343 embryos during 478 cycles of IVF resulted in 107 pregnancies (22.4%), with 125 viable embryos remaining by 6-8 weeks gestation. There was no significant difference between the intercourse and abstain groups in relation to the pregnancy rate (23.6 and 21.2% respectively), but the proportion of transferred embryos that were viable at 6-8 weeks was significantly higher in women exposed to semen compared to those who abstained (11.01 versus 7.69 viable embryos per 100 transferred embryos, P = 0.036, odds ratio 1.48, 95% confidence interval 1.01-2.19). Hence exposure to semen around the time of embryo transfer increases the likelihood of successful early embryo implantation and development.

Increased adhesiveness in cultured endometrial-derived cells is related to the absence of moesin expression

Human endometrial epithelial cells (EECs) are nonadhesive for embryos throughout most of the menstrual cycle. During the so-called implantation window, the apical plasma membrane of EECs acquire adhesive properties by undergoing a series of morphological and biochemical changes. The human endometrial-derived epithelial cell line, RL95-2, serves as an in vitro model for receptive uterine epithelium because of its high adhesiveness for trophoblast-derived cells. In contrast, the HEC-1-A cell line, which displays poor adhesive properties for trophoblast cells, is considered to be less receptive. The ezrin, radixin, and moesin protein family members, which are present underneath the apical plasma membrane, potentially act to link the cytoskeleton and membrane proteins. In the present study, we have further investigated the adhesive features in these two unrelated endometrial-derived cell lines using an established in vitro model for embryonic adhesion. We have also analyzed the protein pattern and mRNA expression of ezrin and moesin in RL95-2 cells versus HEC-1-A cells. The results demonstrate that RL95-2 cells were indeed more receptive (81% blastocyst adhesion) compared with HEC-1-A cells (46% blastocyst adhesion). An intermediate adhesion rate was found in primary EECs cultured on extracellular matrix gel, thus allowing a partial polarization of these cells (67% blastocyst adhesion). Furthermore, we found that moesin was absent from RL95-2 cells. In contrast, ezrin is expressed in both cell lines, yet it is reduced in adherent RL95-2 cells. Data are in agreement with the hypothesis that uterine receptivity requires down-regulation or absence of moesin, which is a less-polarized actin cytoskeleton.

The human blastocyst regulates endometrial epithelial apoptosis in embryonic adhesion

The implanting blastocyst must appose and adhere to the endometrial epithelium and, subsequently, invade it. Locally regulated uterine epithelial apoptosis induced by the embryo is a crucial step of the epithelial invasion in rodents. To address the physiological relevance of this process in humans, we investigated the effect of single human blastocysts on the regulation of apoptosis in cultured human endometrial epithelial cells (hEEC) in both apposition and adhesion phases of implantation. Here, we report a co-ordinated embryonic regulation of hEEC apoptosis. In the apposition phase, the presence of a blastocyst rescues hEEC from the apoptotic pathway. However, when the human blastocyst adheres to the hEEC monolayer, it induces a paracrine apoptotic reaction. Fas ligand (Fas-L) was present at the embryonic trophoectoderm. Fas was localized at the apical cell surface of hEEC, and flow cytometry revealed that 60% of hEEC express Fas. Neutralizing adhesion assays revealed that the Fas/Fas-L death system may be an important mechanism to cross the epithelial barrier, which is crucial for embryonic adhesion, and the manipulation of this system could have potential clinical implications as an interceptive mechanism.

Embryonic regulation of endometrial molecules in human implantation

Embryonic implantation requires co-ordinated development of the blastocyst and the maternal endometrium. Considerable advances have been made in understanding the cell biology of these partner tissues separately. Nevertheless, communication between these tissues and the reciprocal effects of these tissues on each other constitutes an exciting and as yet unsolved paradigm in reproductive medicine. Crosstalk between the embryo, endometrium and the corpus luteum is known to occur in ruminants and primates, and, more specifically, endometrial-embryonic interactions are reported in rodents and primates. In this review, an in vitro model for analysing the interactions between human endometrial epithelium and blastocyst in the adhesion phase of embryonic implantation is presented. The results of investigations of embryonic regulation of endometrial epithelial molecules such as adhesion molecules, mucins, chemokines and cytoskeleton proteins are also presented.

Embryonic regulation in implantation

Maternal steroid hormones play a critical role in establishing the receptive phase of implantation. In addition to that, the embryo is able to modulate endometrial molecules during the apposition phase (chemokines) and the adhesion phase (adhesion and anti-adhesion molecules). Moreover, the human embryo also exerts a coordinated regulation of endometrial epithelial apoptosis during these implantation phases. In this work, we analyze the embryonic regulation of implantation in humans using an in vitro model.

Ovarian stimulation and endometrial receptivity

Endometrial receptivity is a limiting step in the success of in-vitro fertilization (IVF). To investigate this issue, we selected a specific population of high responder patients in whom implantation was impaired, even when good quality embryos were transferred. We present a series of studies showing that high oestradiol concentrations on the day of human chorionic gonadotrophin (HCG) administration are detrimental to uterine receptivity. In addition, we suggest clinical strategies to improve endometrial receptivity in high responder patients using a step-down regimen.

Embryonic implantation

Embryo implantation is a progressive process which requires a communication between two different organisms, and consists of three consecutive phases: apposition, adhesion and invasion. It must be realized throughout the period called "window of implantation", which is characterized by morphological and biochemical changes in the endometrium, as the plasma membrane transformation and the presence of some specific adhesion molecules, chemokines, cytokines, growth factors, and invasive proteinases. All of then acting in a paracrine/autocrine manner, and drive by endocrine hormones.