Novel embryo selection techniques to increase embryo implantation in IVF attempts

Origin and development of uniparental and polyploid blastomeres

Whole-genome (WG) abnormalities, such as uniparental diploidy and triploidy, cause fetal death. Occasionally, they coexist with biparental diploid cells in live births. Understanding the origin and early development of WG abnormal blastomeres is crucial for explaining the formation of androgenotes, gynogenotes, triploidy, chimerism, and mixoploidy. By haplotyping 118 bovine blastomeres from the first cleavages, we identified that heterogoneic division occurs in both multipolar and bipolar cleaving zygotes. During heterogoneic division, parental genomes segregate into distinct blastomeres, resulting in the coexistence of uniparental and biparental diploid or polyploid cells. After culturing the totipotent blastomeres to three preimplantation stages and exploring transcriptomes of 446 cells, we discovered that stress responses contribute to developmental impairment in WG abnormal cells, resulting in either cell arrest or blastocyst formation. Their dominance in preimplantation embryos represents an overlooked cause of abnormal development. Haplotype-based screening could improve in vitro fertilization outcomes.

The ovarian stimulation regimen does not affect aneuploidy or blastocyst rate

RESEARCH QUESTION

Could the total dose (<3000 IU or ≥3000 IU) and type of exogenous gonadotrophin (i.e. recombinant FSH and/or human menopausal gonadotrophin [HMG]) influence aneuploidy and blastulation rates and produce different reproductive outcomes?

DESIGN

This retrospective, observational, multicentre cohort study included a total of 8466 patients undergoing IVF using autologous oocytes and preimplantation genetic testing for aneuploidies. Participants were divided according to the dosage of total gonadotrophins and stratified by maternal age.

RESULTS

The aneuploidy rates, pregnancy outcomes and cumulative live birth rates (CLBR) were similar among women who received total gonadotrophin dosages of <3000 or ≥3000 IU. No statistical differences were reported in the blastulation rate with lower or higher gonadotrophin dosages. Women receiving a higher amount of HMG during ovarian stimulation had a lower aneuploidy rate (P = 0.02); when stratified according to age, younger women with a higher HMG dosage had lower aneuploidy rates (P< 0.001), while no statistical differences were observed in older women with higher or lower HMG dosages. No significant differences were observed in IVF outcomes or CLBR.

CONCLUSIONS

High doses of gonadotrophins were not associated with rate of aneuploidy. However, an increased fraction of HMG in younger women was associated with a lower aneuploidy rate. The study demonstrated that the total gonadotrophin dosage did not influence aneuploidy, reproductive outcomes or CLBR. The increased gonadotrophin and HMG dosages used for ovarian stimulation did not precede aneuploidy, and the use of HMG should be evaluated on a case-by-case basis, according to the individual's characteristics and infertility type.

A comparative analysis of the clinical pregnancy and perinatal outcomes between oocyte vitrification and embryo vitrification based on the propensity score matching method

PURPOSE

This study investigated the safety and effectiveness of oocyte vitrification by comparing the clinical pregnancy and perinatal outcomes between transfer cycles of vitrified oocytes and those of vitrified embryos.

METHODS

A retrospective cohort study was conducted to analyze the clinical data of patients who underwent cleavage-stage embryo transfer at the Department of Reproductive Medicine between January 2011 and June 2021. Seventy-seven transfer cycles of fresh cleavage-stage embryos developed from vitrified-thawed oocytes (oocyte vitrification group) and 2170 transfer cycles of vitrified-thawed cleavage-stage embryos developed from fresh oocytes (embryo vitrification group) were included. Further, 293 cases were selected from the embryo vitrification group after applying propensity score matching at 1:4. The primary outcomes were miscarriage rate, live birth rate, and neonatal birth weight.

RESULTS

No statistically significant differences were observed in the baseline data, pregnancy, perinatal outcomes, or neonatal outcomes for either singleton or twin births between the two groups after matching. Backwards stepwise regression was used to analyze the length of gestation. The age of female participants (β =  - 0.410, 95% CI =  - 1.339 ~  - 0.620, P < 0.001) had a statistically significant effect.

CONCLUSION

Oocyte vitrification results in similar clinical pregnancy and perinatal outcomes as does embryo vitrification; hence, it is a relatively safe assisted reproductive technique.

RNA sequencing-based transcriptome analysis of granulosa cells from follicular fluid: Genes involved in embryo quality during in vitro fertilization and embryo transfer

BACKGROUND

Granulosa cells play an important role in folliculogenesis, however, the role of RNA transcripts of granulosa cells in assessing embryo quality remains unclear. Therefore, we aims to investigate that RNA transcripts of granulosa cells be used to assess the probability of the embryonic developmental capacity.

METHODS

This prospective cohort study was attempted to figure out the probability of the embryonic developmental capacity using RNA sequencing of granulosa cells. Granulosa cells were collected from 48 samples in good-quality embryo group and 79 in only poor- quality embryo group from women undergoing in vitro fertilization and embryo transfer treatment. Three samples from each group were used for RNA sequencing.

RESULTS

226 differentially expressed genes (DEGs) were related to high developmental competence of embryos. Gene Ontology enrichment analysis indicated that these DEGs were primarily involved in biological processes, molecular functions, and cellular components. Additionally, pathway analysis revealed that these DEGs were enriched in 13 Kyoto Encyclopedia of Genes and Genomes pathways. Reverse transcription quantitative polymerase chain reaction verified the differential expression of the 13 selected DEGs. Among them,10 genes were differently expressed in the poor-quality embryo group compared to good-quality embryo group, including CSF1R, CTSH, SERPINA1, CYP27A1, ITGB2, IL1β, TNF, TAB1, BCL2A1, and CCL4.

CONCLUSIONS

RNA sequencing data provide the support or confute granulosa expressed genes as non-invasive biomarkers for identifying the embryonic developmental capacity.

One Plus One is Better than Two: An Approach Towards a Single Blastocyst Transfer Policy for All IVF Patients

OBJECTIVE

 It is known that the single embryo transfer (SET) is the best choice to reduce multiples and associated risks. The practice of cryopreserving all embryos for posterior transfer has been increasingly performed for in vitro fertilization (IVF) patients at the risk of ovarian hyperstimulation syndrome or preimplantation genetic testing for aneuploidy. However, its widespread practice is still controverse. The aim of this study was to evaluate how effective is the transfer of two sequential SET procedures compared with a double embryo transfer (DET) in freeze-only cycles.

METHODS

 This retrospective study reviewed 5,156 IVF cycles performed between 2011 and 2019, and 506 cycles using own oocytes and freeze-only policy with subsequent elective frozen-thawed embryo transfers (eFET) were selected for this study. Cycles having elective SET (eSET, n = 209) comprised our study group and as control group we included cycles performed with elective DET (eDET, n = 291). In the eSET group, 57 couples who had failed in the 1^st eSET had a 2^nd eFET, and the estimated cumulative ongoing pregnancy rate was calculated and compared with eDET.

RESULTS

 After the 1^st eFET, the ongoing pregnancy rates were similar between groups (eSET: 35.4% versus eDET: 38.5%; p = 0.497), but the estimated cumulative ongoing pregnancy rate after a 2^nd eFET in the eSET group (eSET + SET) was significantly higher (48.8%) than in the eDET group (p < 0.001). Additionally, the eSET + SET group had a 2.7% rate of multiple gestations, which is significantly lower than the eDET group, with a 30.4% rate (p < 0.001).

CONCLUSION

 Our study showed the association of freeze-only strategy with until up to two consecutive frozen-thawed eSETs resulted in higher success rates than a frozen-thawed DET, while drastically reducing the rate of multiple pregnancies.

The relationship between good quality embryo rates and IVF outcomes/embryo transfer policies in extended embryo culture

This study aims to investigate which parameters affect the change in good quality embryo rates during the cleavage stage and whether they have any effect on embryo transfer policies and IVF results. We analysed changes in good quality embryo (grades 1 and 2) rates during the period on days 2, 3 and 5; patients with five or fewer embryos (group 1), 6-10 embryos (group 2) and more than 10 embryos (group 3). The good quality embryo rates decreased in all groups on day 5. When the infertility reasons are studied among all of the groups, ovulatory dysfunction is found to be significantly higher in group 2 compared to group 1 and unexplained infertility was found to be significantly higher in group 2 compared to group 1 and group 3. Total antral follicle, mature oocyte and total oocyte counts were found to be significantly lower in group 1. However, there is no significant difference found among all of the groups for β-HCG levels and clinical pregnancies. Changes in good quality embryo rates at the cleavage stage in extended embryo culture do not have an impact on IVF results.IMPACT STATEMENTWhat is already known on this subject? The number and quality of embryos in the cleavage stage are important parameters affecting the embryo transfer decision on day 5. There is still insufficient knowledge concerning changes in the percentage of increased good quality embryo transfers associated with IVF outcomes during the second to the third day, and the third to the fifth day.What do the results of this study add? Day 5 embryo transfer is possible in patients with a low number of embryos, according to our results. The good quality embryo rates of patients with a low number of embryos at the cleavage stage are more promising compared to patients having more than five embryos.What are the implications of these findings for clinical practice and/or further research? An extended embryo culture option can be used on patients with a low number of embryos for clinical practice.

Dysregulation of the interleukin-17A pathway in endometrial tissue from women with unexplained infertility affects pregnancy outcome following assisted reproductive treatment

STUDY QUESTION

Which transcriptomic alterations in mid-luteal endometrial scratch biopsies, taken prior to the assisted reproductive treatment (ART) treatment cycle are associated with unsuccessful pregnancy?

SUMMARY ANSWER

Dysregulated interleukin-17 (IL-17) pathway components are demonstrated in women who fail to become pregnant after ART.

WHAT IS KNOWN ALREADY

Implantation failure is now recognised as a critical factor in unexplained infertility and may be an important component of failed ART.

STUDY DESIGN, SIZE, DURATION

Using a prospective longitudinal study design, 29 nulliparous women with unexplained infertility undergoing ART were recruited between October 2016 and February 2018. Mid-luteal stage endometrium and matched serum samples were collected, and patients underwent a single embryo transfer in the subsequent cycle. RNA-seq analysis of endometrial biopsies was performed on the discovery cohort (n = 20).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Gene set enrichment analysis of the differentially expressed genes (DEGs) was performed. Endometrium and serum were then prepared for IL-17A analysis by ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

There were 204 differentially expressed protein-coding genes identified in tissue from women who became pregnant (n = 9) compared with tissue from women who failed to become pregnant (n = 11) (false discovery rate; P < 0.05). Of the 204 DEGs, 166 were decreased while 38 were increased in the pregnant compared to the non-pregnant groups. Gene set enrichment analysis of the DEGs identified an over-representation of IL-17 and Pl3K-Akt signalling pathways. All the DEGs within the IL-17 signalling pathway (MMP3, MMP1, IL1β, LCN2, S100A9 and FOSL1) demonstrated decreased expression in the pregnant group. Serum IL-17 protein levels were increased in the non-pregnant discovery cohort (n = 11) and these findings were confirmed a validation cohort (n = 9).

LIMITATIONS, REASONS FOR CAUTION

Limitations of our study include the cohort size and the lack of aneuploidy data for the embryos; however, all embryos transferred were single good or top-quality blastocysts.

WIDER IMPLICATIONS OF THE FINDINGS

These findings demonstrate dysregulated IL-17 pathway components in women who fail to become pregnant after ART. Elevated serum levels of the pro-inflammatory cytokine IL-17 may predict failure of ART in women with unexplained infertility. Future trials of anti-IL-17 therapies in this cohort warrant further investigation.

STUDY FUNDING/COMPETING INTEREST(S)

Funding from the UCD Wellcome Institutional Strategic Support Fund, which was financed jointly by University College Dublin and the SFI-HRB-Wellcome Biomedical Research Partnership (ref 204844/Z/16/Z), is acknowledged. The authors have no competing interests.

TRIAL REGISTRATION NUMBER

NA.

Increased copy number of syncytin-1 in the trophectoderm is associated with implantation of the blastocyst

Background

A key step in embryo implantation is the adhesion to and invasion of the endometrium by the blastocyst trophectoderm. The envelope proteins of HERV-W and -FRD (human endogenous retrovirus-W and -FRD), syncytin-1 and syncytin-2, are mainly distributed in the placenta, and play important roles in the development of the placenta. The placenta originates from the trophectoderm of the blastocyst. It is unclear whether the envelope proteins of HERV-W and -FRD have an effect on the development of the trophectoderm and whether they have any association with the implantation of the blastocyst.

Methods

The whole-genome amplification products of the human blastocyst trophectoderm were used to measure the copy number of syncytin-1 and syncytin-2 using real time qPCR. In addition, clinical data associated with the outcome of pregnancies was collected, and included age, body mass index (BMI), basic follicle stimulating hormone(bFSH), rate of primary infertility and oligo-astheno-teratospermia, the thickness of the endometrium on the day of endometrial transformation, the levels of estrogen and progestin on the transfer day, the days and the morphological scores of the blastocysts. The expression of mRNA and the copy numbers of syncytin-1 and syncytin-2 in H1 stem cells, and in differentiated H1 cells, induced by BMP4, were measured using real time qPCR.

Results

The relative copy number of syncytin-1 in the pregnant group (median: 424%, quartile: 232%-463%, p < 0.05) was significantly higher than in the non-pregnant group (median: 100%, quartile: 81%-163%). There was a correlation (r _s  = 0.681, p < 0.001) between the copy number of syncytin-1 and blastocyst implantation after embryo transfer. As the stem cells differentiated, the expression of NANOG mRNA decreased, and the expression of caudal type homeobox 2(CDX2) and β-human chorionic gonadotropin (β-hCG) mRNAs increased. Compared to the undifferentiated cells, the relative expression of the syncytin-1 mRNA was 1.63 (quartile: 0.59-6.37, p > 0.05), 3.36 (quartile: 0.85-14.80, p > 0.05), 10.85 (quartile: 3.39-24.46, p < 0.05) and 67.81 (quartile: 54.07-85.48, p < 0.05) on day 1, 3, 5 and 7, respectively, after the differentiation. The relative expression of syncytin-2 was 5.34 (quartile: 4.50-10.30), 7.90 (quartile: 2.46-14.01), 57.44 (quartile: 38.35-103.87) and 344.76 (quartile: 267.72-440.10) on day 1, 3, 5 and 7, respectively, after the differentiation (p < 0.05). The copy number of syncytin-1 increased significantly during differentiation.

Conclusion

Preceding the transfer of frozen embryos, the increased copy number of syncytin-1 in the blastocyst trophectoderm was associated with good outcomes of pregnancies.

The impact of accurately timed mid-luteal endometrial injury in nulligravid women undergoing their first or second embryo transfer

INTRODUCTION

Endometrial injury or 'scratch' preceding an assisted reproductive therapy (ART) cycle has recently been shown not to improve livebirth rates among women undergoing ART. The objective of this study was to compare pregnancy outcomes in nulliparous women who underwent an accurately timed mid-luteal scratch biopsy prior to ART with those who did not.

METHODS

This was a prospective cohort study. Women were recruited between October 2016 and February 2018 inclusive. Women who met the inclusion criteria and who did not undergo an endometrial scratch in the study period were used as a comparison group. Patients underwent a cycle of ART in the menstrual cycle following endometrial scratch.

RESULTS

Ninety-eight women were eligible for participation in the study. There were no differences in rates of implantation (35.7% (n = 20/56) vs. 35.4% (n = 17/48); p = 1.00), clinical pregnancy (40.0% (n = 20/50) vs. 39.5% (n = 17/43); p = 1.00) or live birth (34.0% (n = 17/50) vs. 25.6% (n = 11/43); p = 0.50) per embryo transfer between those who underwent a scratch and those who did not.

CONCLUSION

Endometrial scratch is a simple, inexpensive and low-risk procedure. However, in this relatively small cohort study, no differences in rates of implantation, clinical pregnancy or live birth in women with primary infertility were determined between those who underwent a scratch and those who did not.

Pronuclear and blastocyst morphology are associated age-dependently with embryo ploidy in in vitro fertilization cycles

This retrospective study aimed to assess the relationship between standard markers of embryo morphology, maternal age and blastocyst ploidy determined by trophectoderm (TE) biopsy and Next-generation Sequencing (NGS). A total of 774 oocytes and embryos from 288 PGT-A cycles were scored for pronuclear, cleavage stage and blastocyst morphology. Pronuclear oocytes aligned between the nuclei and presenting equal number of nucleolus precursor bodies (NPBs) were designated Z1, oocytes showing equal number of NPBs, but not aligned, as Z2 while Z3 oocytes had an unequal number of NBPs between the nuclei or NPBs aligned in one nucleus and non-aligned in the other. Pronuclear oocytes with unequal-sized or non-aligned nuclei were designated Z4. Blastocysts were graded as BL1 (AA, AB or BA), BL2 (BB or CB) and BL3 (BC or CC) based on the combination of inner cell mass (ICM) and TE scores. Pronuclear and blastocyst morphology were correlated with aneuploidy in a < 40-year-old group (p < 0.01 and p < 0.05, respectively), but not in those ≥40 years. Interestingly, BL3 blastocysts classified as Z1 or Z3-Z4 on day-1 had different aneuploidy rates (BL3/Z1 = 46.7% vs. BL3/Z3-Z4 = 90.0%, p < 0.05). In summary, our data showed that pronuclear and blastocyst morphology are associated with blastocyst ploidy in younger patients. This may help embryo selection for embryo transfer and decision-making on which blastocysts should be biopsied in PGT-A cycles.

The effect on twinning rate of transferring double vitrified-warmed embryos in women of advanced reproductive age: a retrospective study

Twin pregnancies are associated with greater risk of neonatal morbidity and mortality than a singleton. This study was performed to investigate the twin pregnancy rate when two vitrified-warmed embryos are transferred in women of advanced reproductive age (≥35 years at the time of oocyte retrieval) and to evaluate the implications of findings in selecting candidates for elective single embryo transfer (eSET). A retrospective analysis of data which included 2,038 women aged 35–45 years, who underwent vitrified-warmed double embryo transfer (DET), from January 2013 to December 2016 was undertaken. Pregnancy and twin rates were estimated after stratifying by prognostic profile. The twin pregnancy rate was lower in women with poor prognosis (12/96, 12.5%) as compared with that in women with favorable prognosis (102/374, 27.3%) and average prognosis (78/346, 22.5%) with significant differences (P < 0.05). The twin rate for women with favorable prognosis was 29.2% (70/240) in the cycles of women aged 35–37 years, 26.8% (26/97) in the cycles of women aged 38–40 years and 16.2% (6/37) in the cycles of women >40 years. The twin rate for women with average prognosis was 25.8% (51/198) in the cycles of women aged 35–37 years, 22.0% (22/100) in the cycles of women aged 38–40 years and 10.4% (5/48) in the cycles of women >40 years. The twin rate for women with poor prognosis was 15.3% (9/59) in the cycles of women aged 35–37 years, 10.3% (3/29) in the cycles of women aged 38–40 years and 0% (0/8) in the cycles of women >40 years. From these results, it was concluded that women with a favorable or average prognosis have a high risk of twin pregnancies. The finding can be used to guide future practice: that is, performing eSET in women with favorable or average prognosis and DET in women with poor prognosis.

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.

Day 3 embryo transfer versus day 5 blastocyst transfers: A prospective randomized controlled trial

OBJECTIVE

This study aimed to show whether transferring day 5 embryos resulted in higher implantation and pregnancy rates than transferring day 3 embryos in Turkish women undergoing an intracytoplasmic sperm injection (ICSI) cycle.

MATERIALS AND METHODS

A total of 190 women who had ICSI after retrieval of more than four oocytes on the day of fertilization check were randomly assigned to undergo embryo transfer either on day 3 or day 5.

RESULTS

Day 3 and day 5 transfers were statistically similar with respect to the age of woman (p=0.107), duration of infertility (p=0.528), cause of infertility (p=0.850), number of collected oocytes (p=0.119), number of metaphase II oocytes (p=0.178), number of fertilized oocytes (p=0.092), and number of transferred embryos (p=0.556). The number of grade 1 embryos was significantly higher in day 5 transfers than in day 3 transfers (p=0.001). Day 3 and day 5 embryo transfers had statistically similar implantation, clinical pregnancy, twinning, and live birth rates (p=0.779, p=0.771, p=0.183, and p=0.649, respectively). The live birth rates in singleton pregnancies conceived after day 3 and day 5 embryo transfers were statistically similar (p=0.594).

CONCLUSION

The efficacy of blastocyst transfer is not inferior to that of embryo transfer on cleavage stage. Performing blastocyst transfer may have benefits because it is associated with acceptable pregnancy rates and morphologic assessment on day 3 has limited predictive value for subsequent embryonic development.