Impact of pre-treatment in GnRH-antagonist cycles triggered with GnRH agonist on reproductive outcomes

OBJECTIVE

Pre-treatment (PT) therapies in IVF are known to be used as pre-stimulation modality to improve cycle outcomes. This study aims to assess whether PT in GnRH antagonist cycles triggered with GnRH-agonist impact oocyte maturation response.

METHODS

Data were retrospectively collected for patients who underwent GnRH antagonist cycle with agonist triggering with and without PT. The patients were allocated to groups according to their PT status. The primary outcome evaluated was suboptimal maturation response. Suboptimal maturation to trigger was defined as no oocyte upon retrieval when adequate response was expected.

RESULTS

The study population included 196 patients who underwent GnRH antagonist cycle with agonist triggering. The study group included 69 patients who received PT. The control group included 127 patients with no PT. In univariate analysis, the PT group significantly displayed suboptimal response compared to the controls (p = 0.008). All the patients in the study group with suboptimal response (with or without hCG re-triggering) were treated with GnRH-agonist as PT. Basal and pre-trigger LH values were significantly lower in the study group compared to controls (p < 0.001). Multivariate regression analysis revealed that PT with GnRH agonist was a significant predictor for suboptimal response.

CONCLUSIONS

Pre-treatment, and particularly the use of GnRH-agonist as PT in antagonist cycles triggered with agonist, increases the risk of suboptimal response to GnRH-agonist trigger. This might be explained by prolonged pituitary suppression, which lasts beyond the PT cessation.

Stain-Free Sperm Analysis and Selection for Intracytoplasmic Sperm Injection Complying with WHO Strict Normal Criteria

This multi-center study evaluated a novel microscope system capable of quantitative phase microscopy (QPM) for label-free sperm-cell selection for intracytoplasmic sperm injection (ICSI). Seventy-three patients were enrolled in four in vitro fertilization (IVF) units, where senior embryologists were asked to select 11 apparently normal and 11 overtly abnormal sperm cells, in accordance with current clinical practice, using a micromanipulator and 60× bright field microscopy. Following sperm selection and imaging via QPM, the individual sperm cell was chemically stained per World Health Organization (WHO) 2021 protocols and imaged via bright field microscopy for subsequent manual measurements by embryologists who were blinded to the QPM measurements. A comparison of the two modalities resulted in mean differences of 0.18 µm (CI -0.442-0.808 µm, 95%, STD-0.32 µm) for head length, -0.26 µm (CI -0.86-0.33 µm, 95%, STD-0.29 µm) for head width, 0.17 (CI -0.12-0.478, 95%, STD-0.15) for length-width ratio and 5.7 for acrosome-head area ratio (CI -12.81-24.33, 95%, STD-9.6). The repeatability of the measurements was significantly higher in the QPM modality. Surprisingly, only 19% of the subjectively pre-selected normal cells were found to be normal according to the WHO2021 criteria. The measurements of cells imaged stain-free through QPM were found to be in good agreement with the measurements performed on the reference method of stained cells imaged through bright field microscopy. QPM is non-toxic and non-invasive and can improve the clinical effectiveness of ICSI by choosing sperm cells that meet the strict criteria of the WHO2021.

Noninvasive Pregestational Genetic Testing of Embryos Using Smart Sensors Array

Pregestational genetic testing of embryos is the conventional tool in detecting genetic disorders (fetal aneuploidy and monogenic disorders) for in vitro fertilization (IVF) procedures. The accepted clinical practice for genetic testing still depends on biopsy, which has the potential to harm the embryo. Noninvasive genetic prenatal testing has not yet been achieved. In this study, embryos with common genetic disorders created through IVF were tested with an artificially intelligent nanosensor array. Volatile organic compounds emitted by the culture fluid of embryos were analyzed with chemical gas sensors. The obtained results showed significant discrimination between the embryos with different genetic diseases and their wild-types. Embryos were obtained from the same clinical center for avoiding differences based on clinical and demographical characteristics. The achieved discrimination accuracy was 81% for PKD disease, 90% for FRAX disease, 85% for HOCM disease, 90% for BRCA disease, and 100% for HSCR disease. These proof-of-concept findings might launch the development of a noninvasive approach for early assessment of embryos by examining the culture fluid of the embryos, potentially enabling noninvasive diagnosis and screening of genetic diseases for IVF.

Clinical outcome of planned oocyte cryopreservation at advanced age

PURPOSE

To report outcome of planned oocyte cryopreservation (POC) in the first 8 years of this treatment in our center.

METHODS

A retrospective study in a university-affiliated medical center.

RESULTS

A total of 446 women underwent POC during 2011-2018. Fifty-seven (13%) women presented to use these oocytes during the study period (until June 2021). POC was performed at a mean age of 37.9 ± 2.0 (range 33-41). Age at thawing was 43.3 ± 2.1 (range 38-49). A total of 34 (60%) women transferred their oocytes for thawing at other units. Oocyte survival after thawing was significantly higher at our center than following shipping to ancillary sites (78 vs. 63%, p = 0.047). Forty-nine women completed their treatment, either depleting their cryopreserved oocytes without conceiving (36) or attaining a live birth (13)-27% live birth rate per woman. Only one of eleven women who cryopreserved oocytes aged 40 and older had a live birth using thawed oocytes.

CONCLUSION

Women should be advised to complete planned oocyte cryopreservation before age 40, given low success rates in women who underwent cryopreservation at advanced reproductive age. In this study, oocyte shipping was associated with lower survival rate. These findings may be relevant for women considering POC and utilization of cryopreserved oocytes.

Loss of heterochromatin and retrotransposon silencing as determinants in oocyte aging

Mammalian oocyte quality reduces with age. We show that prior to the occurrence of significant aneuploidy (9M in mouse), heterochromatin histone marks are lost, and oocyte maturation is impaired. This loss occurs in both constitutive and facultative heterochromatin marks but not in euchromatic active marks. We show that heterochromatin loss with age also occurs in human prophase I-arrested oocytes. Moreover, heterochromatin loss is accompanied in mouse oocytes by an increase in RNA processing and associated with an elevation in L1 and IAP retrotransposon expression and in DNA damage and DNA repair proteins nuclear localization. Artificial inhibition of the heterochromatin machinery in young oocytes causes an elevation in retrotransposon expression and oocyte maturation defects. Inhibiting retrotransposon reverse-transcriptase through azidothymidine (AZT) treatment in older oocytes partially rescues their maturation defects and activity of the DNA repair machinery. Moreover, activating the heterochromatin machinery via treatment with the SIRT1 activating molecule SRT-1720, or overexpression of Sirt1 or Ezh2 via plasmid electroporation into older oocytes causes an upregulation in constitutive heterochromatin, downregulation of retrotransposon expression, and elevated maturation rates. Collectively, our work demonstrates a significant process in oocyte aging, characterized by the loss of heterochromatin-associated chromatin marks and activation of specific retrotransposons, which cause DNA damage and impair oocyte maturation.

'Why have women not returned to use their frozen oocytes?': a 5-year follow-up of women after planned oocyte cryopreservation

RESEARCH QUESTION

What are the reproductive choices and retrospective reflections of women at least 4 years after planned oocyte cryopreservation (POC)?

DESIGN

This was an internet survey, using the REDCap application, of women who underwent POC, at a single-centre university-affiliated IVF unit, 4-8 years before the survey. The questionnaire addressed reproductive choices and outcomes following POC.

RESULTS

Seventy-nine women who underwent POC during 2011-2014 were invited to participate, and 70 (89%) responded. Mean age at cryopreservation was 37.1 ± 2.4 (range 30-41) years, mean age at study participation 42.6 ± 2.6 (range 35-48) years, and mean time from first cryopreservation cycle to study participation 5.5 ± 1.3 (range 4-8) years. The main retrospectively reported reason for POC was not wanting to become pregnant without a partner (59, 84%). During the follow-up period, 44 women (63%) attempted to conceive either naturally or by assisted reproductive technology using fresh or cryopreserved oocytes. Of those, 28 women achieved a live birth (64% of those who tried to conceive). Fourteen respondents (20% of all respondents) reported using their cryopreserved oocytes, and three (21%) achieved a birth using those oocytes. Fifteen women (34%) of those who tried to conceive used donor spermatozoa.

CONCLUSIONS

The most common reasons for not using frozen oocytes were achieving pregnancy without frozen oocytes or preferring not to have a child without a partner. A considerable proportion of women who had POC and were not interested in being a single parent by choice eventually try to conceive using donor spermatozoa several years later.

The effect of repeated biopsy on pre-implantation genetic testing for monogenic diseases (PGT-M) treatment outcome

PURPOSE

To study the outcome of repeated biopsy for pre-implantation genetic testing in case of failed genetic diagnosis in the first biopsy.

METHODS

The study group included 81 cycles where embryos underwent re-biopsy because there were no transferable embryos after the first biopsy: in 55 cycles, the first procedure was polar body biopsy (PBs) and the second cleavage-stage (BB); in 26 cycles, the first was BB and the second trophectoderm (BLAST) biopsy. The control group included 77 cycles where embryos underwent successful genetic diagnosis following the first biopsy, matched by maternal age, egg number, genetic inheritance type, and embryonic stage at the first biopsy. We measured genetic diagnosis rate, clinical pregnancy rates (PRs), live-birth rates (LBRs), gestational age, and birth weight.

RESULTS

For repeated biopsy, genetic diagnosis was received in 67/81 cycles (82.7%); at a higher rate in PB + BB than in BB + BLAST (49/55, 89.1% and 18/26, 69.2% respectively, p = 0.055). Transferable embryos were found in 47 and 68 cycles in the study and the control groups. PRs/ET were 20/47 (42.6%) and 36/68 (52.9%) (p = 0.27), 16/36 (44.4%) following PB + BB, and 4/11 (36.4%) following BB + BLAST (p = 0.74). LBRs/ET were 13/47 (27.7%) in study group, and 28/68 (41.2%) in the controls (p = 0.14), 10/36 (27.8%) following PB + BB group, and 3/11 (27.3%) following BB + BLAST (p > 0.99). Gestational age and birth weight were similar in all groups.

CONCLUSIONS

Re-biopsy of embryos when no genetic diagnosis could be reached following the first biopsy, achieved high rates of genetic diagnosis, pregnancies, and live births.

Prediction value of anti-Mullerian hormone (AMH) serum levels and antral follicle count (AFC) in hormonal contraceptive (HC) users and non-HC users undergoing IVF-PGD treatment

Use of hormone contraceptives (HC) is very popular in the reproductive age and, therefore, evaluation of ovarian reserve would be a useful tool to accurately evaluate the reproductive potential in HC users. We conducted a retrospective cohort study of 41 HC users compared to 57 non-HC users undergoing IVF-preimplantation genetic diagnosis (PGD) aiming to evaluate the effect of HC on the levels of anti-Mullerian hormone (AMH), small (2-5 mm), large (6-10 mm) and total antral follicle count (AFC) and the ability of these markers to predict IVF outcome. Significant differences in large AFC (p = 0.04) and ovarian volume (p < 0.0001) were seen, however, there were no significant differences in small and total AFC or in serum AMH and FSH levels. Oocyte number significantly correlated with AMH and total AFC in HC users (p < 0.001) while in non-HC users these correlations were weaker. In HC users, the significant predictors of achieving <6 and >18 oocytes were AFC (ROC-AUC; 0.958, p = 0.001 and 0.883, p = 0.001) and AMH (ROC-AUC-0.858, p = 0.01 and 0.878, p = 0.001), respectively. The predictive values were less significant in non-HC users. These findings are important in women treated for PGD, in ovum donors and for assessing the fertility prognosis in women using HC and wishing to postpone pregnancy.

Cryopreserved embryo transfer: adjacent or non-adjacent to failed fresh long GnRH-agonist protocol IVF cycle

The optimal time to perform cryopreserved embryo transfer (CET) after a failed oocyte retrieval-embryo transfer (OR-ET) cycle is unknown. Similar clinical pregnancy rates were recently reported in immediate and delayed CET, performed after failed fresh OR-ET, in cycles with the gonadotrophin-releasing hormone (GnRH) antagonist protocol. This study compared outcomes of CET performed adjacently (<50 days, n = 67) and non-adjacently (≥50 to 120 days, n = 62) to the last OR-day of cycles with the GnRH agonist down-regulation protocol. Additional inclusion criteria were patients' age 20-38 years, the transfer of only 1-2 cryopreserved embryos, one treatment cycle per patient and artificial preparation for CET. Significantly higher implantation, clinical pregnancy and live birth rates were found in the non-adjacent group than in the adjacent group: 30.5% versus 11.3% (P = 0.001), 41.9% versus 17.9% (P = 0.003) and 32.3% versus 13.4% (P = 0.01), respectively. These results support the postponement of CET after a failed OR-ET for at least one menstrual cycle, when a preceding long GnRH-agonist protocol is used.

Establishment of Homozygote Mutant Human Embryonic Stem Cells by Parthenogenesis

We report on the derivation of a diploid 46(XX) human embryonic stem cell (HESC) line that is homozygous for the common deletion associated with Spinal muscular atrophy type 1 (SMA) from a pathenogenetic embryo. By characterizing the methylation status of three different imprinted loci (MEST, SNRPN and H19), monitoring the expression of two parentally imprinted genes (SNRPN and H19) and carrying out genome-wide SNP analysis, we provide evidence that this cell line was established from the activation of a mutant oocyte by diploidization of the entire genome. Therefore, our SMA parthenogenetic HESC (pHESC) line provides a proof-of-principle for the establishment of diseased HESC lines without the need for gene manipulation. As mutant oocytes are easily obtained and readily available during preimplantation genetic diagnosis (PGD) cycles, this approach should provide a powerful tool for disease modelling and is especially advantageous since it can be used to induce large or complex mutations in HESCs, including gross DNA alterations and chromosomal rearrangements, which are otherwise hard to achieve.

Uncovering the Role of Hypermethylation by CTG Expansion in Myotonic Dystrophy Type 1 Using Mutant Human Embryonic Stem Cells

CTG repeat expansion in DMPK, the cause of myotonic dystrophy type 1 (DM1), frequently results in hypermethylation and reduced SIX5 expression. The contribution of hypermethylation to disease pathogenesis and the precise mechanism by which SIX5 expression is reduced are unknown. Using 14 different DM1-affected human embryonic stem cell (hESC) lines, we characterized a differentially methylated region (DMR) near the CTGs. This DMR undergoes hypermethylation as a function of expansion size in a way that is specific to undifferentiated cells and is associated with reduced SIX5 expression. Using functional assays, we provide evidence for regulatory activity of the DMR, which is lost by hypermethylation and may contribute to DM1 pathogenesis by causing SIX5 haplo-insufficiency. This study highlights the power of hESCs in disease modeling and describes a DMR that functions both as an exon coding sequence and as a regulatory element whose activity is epigenetically hampered by a heritable mutation.

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We identify a disease-associated, differentially methylated region in DM1 hESCs

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CTG expansion size correlates with the degree of methylation specifically in DM1 hESCs

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DMPK hypermethylation hampers the activity of a regulatory element for SIX5

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DM1 hESCs provide an opportunity to study diseased cardiomyocytes in vitro

FMR1 epigenetic silencing commonly occurs in undifferentiated fragile X-affected embryonic stem cells

Fragile X syndrome (FXS) is the most common heritable form of cognitive impairment. It results from epigenetic silencing of the X-linked FMR1 gene by a CGG expansion in its 5′-untranslated region. Taking advantage of a large set of FXS-affected human embryonic stem cell (HESC) lines and isogenic subclones derived from them, we show that FMR1 hypermethylation commonly occurs in the undifferentiated state (six of nine lines, ranging from 24% to 65%). In addition, we demonstrate that hypermethylation is tightly linked with FMR1 transcriptional inactivation in undifferentiated cells, coincides with loss of H3K4me2 and gain of H3K9me3, and is unrelated to CTCF binding. Taken together, these results demonstrate that FMR1 epigenetic gene silencing takes place in FXS HESCs and clearly highlights the importance of examining multiple cell lines when investigating FXS and most likely other epigenetically regulated diseases.

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FMR1 epigenetic gene silencing commonly occurs in the undifferentiated FXS cells

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FXS HESCs are heterogeneous for repeat size and methylation levels

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This study underscores the importance of multiple HESC lines in disease modeling

Novel heparan mimetics potently inhibit the scrapie prion protein and its endocytosis

During prion diseases the normal prion protein PrP(C) is refolded into an abnormal conformer PrP(Sc). We have studied the PrP(Sc) inhibiting activity of a library of synthetic heparan mimetic (HM) biopolymers. HMs are chemically derived dextrans obtained by successive substitutions with carboxymethyl, benzylamide, and sulfate groups on glucose residues. Some HMs eliminated PrP(Sc) from prion-infected cells after a 5 day course at 100 ng/ml and were 15 x potent than pentosan sulfate in this system. The anti-PrP(Sc) activity of HMs correlated with the degree of sulfation but was increased by benzylamidation. HMs did not reduce the synthesis of PrP(C) nor its attachment to lipid rafts, but instead blocked its conversion into PrP(Sc). The anti-PrP(Sc) HMs also prevented the uptake of prion rods by cultured cells. HMs may thus block the interaction of PrP(Sc) with a putative cellular receptor, possibly heparan sulfate. HMs provide an attractive chemical approach for the synthesis of TSE therapeutic and prophylactic reagents.

Protease-sensitive scrapie prion protein in aggregates of heterogeneous sizes

The pathological prion protein PrP(Sc) is the only known component of the infectious prion. In cells infected with prions, PrP(Sc) is formed posttranslationally by the refolding of the benign cell surface glycoprotein PrP(C) into an aberrant conformation. The two PrP isoforms possess very different properties, as PrP(Sc) has a protease-resistant core, forms very large amyloidic aggregates in detergents, and is only weakly immunoreactive in its native form. We now show that prion-infected rodent brains and cultured cells contain previously unrecognized protease-sensitive PrP(Sc) varieties. In both ionic (Sarkosyl) and nonionic (n-octyl beta-D-glucopyranoside) detergents, the novel protease-sensitive PrP(Sc) species formed aggregates as small as 600 kDa, as measured by gel filtration. The denaturation dependence of PrP(Sc) immunoreactivity correlated with the size of the aggregate. The small PrP(Sc) aggregates described here are consistent with the previous demonstration of scrapie infectivity in brain fractions with a sedimentation coefficient as small as 40 S [Prusiner et al. (1980) J. Neurochem. 35, 574-582]. Our results demonstrate for the first time that prion-infected tissues contain protease-sensitive PrP(Sc) molecules that form low MW aggregates. Whether these new PrP(Sc) species play a role in the biogenesis or the pathogenesis of prions remains to be established.

Split invertase polypeptides form functional complexes in the yeast periplasm in vivo

The assembly of functional proteins from fragments in vivo has been recently described for several proteins, including the secreted maltose binding protein in Escherichia coli. Here we demonstrate for the first time that split gene products can function within the eukaryotic secretory system. Saccharomyces cerevisiae strains able to use sucrose produce the enzyme invertase, which is targeted by a signal peptide to the central secretory pathway and the periplasmic space. Using this enzyme as a model we find the following: (i) Polypeptide fragments of invertase, each containing a signal peptide, are independently translocated into the endoplasmic reticulum (ER) are modified by glycosylation, and travel the entire secretory pathway reaching the yeast periplasm. (ii) Simultaneous expression of independently translated and translocated overlapping fragments of invertase leads to the formation of an enzymatically active complex, whereas individually expressed fragments exhibit no activity. (iii) An active invertase complex is assembled in the ER, is targeted to the yeast periplasm, and is biologically functional, as judged by its ability to facilitate growth on sucrose as a single carbon source. These observation are discussed in relation to protein folding and assembly in the ER and to the trafficking of proteins through the secretory pathway.

Targeting and assembly of an oligomeric bacterial enterotoxoid in the endoplasmic reticulum of Saccharomyces cerevisiae

A hybrid protein consisting of the Escherichia coli lipoprotein signal sequence attached to the mature sequence of the B subunit of heat-labile enterotoxin (Lipo-EtxB) was expressed in yeast and E. coli. Analyses of cell lysates from Saccharomyces cerevisiae and E. coli expressing the protein revealed that both organisms were able to assemble Lipo-EtxB into oligomers that were (i) stable in the presence of sodium dodecyl sulphate, (ii) resistant to proteinase K degradation, and (iii) able to bind to GM1-ganglioside receptors. Each of these properties are characteristic of the wild-type B subunit pentamer produced in E. coli. Assembly of Lipo-EtxB was found to be unaffected in a sec18 mutant of S. cerevisiae, which possesses a temperature-sensitive defect in protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus, but was found not to assemble in a sec53 mutant, which causes the misfolding of proteins targeted to the ER. A kar2-1 mutation with a defect in the yeast homologue of BiP caused an 18-fold reduction in Lipo-EtxB assembly at the non-permissive temperature in S. cerevisiae. However, introduction of the wild-type KAR2 gene on a plasmid into the kar2-1 mutant completely suppressed the inhibition of Lipo-EtxB assembly. This provides the first evidence that KAR2 facilitates the assembly of an oligomeric protein in yeast and thus implicates KAR2 as a 'molecular chaperone'. The possible mechanisms of enterotoxoid assembly in E. coli and S. cerevisiae are discussed.