O-251 Defining the exclusive role of male genome integrity on conceptus development

Study question

To determine the effect of sperm DNA fragmentation on embryo development by ruling out a female factor component.

Summary answer

By utilizing healthy donor oocytes, it is possible to quantify the sole deleterious effect of sperm DNA fragmentation and explore the ooplasmic repair mechanism.

What is known already

In approximately 50% of couples with unexplained ART failure, a subtle male factor is present that is missed in a conventional semen analysis assessing concentration, motility, and morphology. Additional information on male gamete competence can be acquired by assessing Sperm Chromatin Fragmentation (SCF). Indeed, a fragmented male genome can give rise to poorly developing embryos, leading to impaired implantation, lower pregnancy, and higher miscarriage rates. It has been previously seen that an oocyte, according to its age, can repair the damaged DNA contributed by the male gamete.

Study design, size, duration

In last decade, 316 couples, who have an elevated SCF, underwent ICSI cycles and resulted in disappointing clinical outcomes. To exclude an eventual confounding female factor, couples who utilized donor oocytes were identified and clinical outcome was compared to a control. To measure the role of an impaired sperm genome and a concurrent oocyte repair mechanism, we compared clinical outcomes between cycles in the same couples who used their own and subsequently donor oocytes.

Participants/materials, setting, methods

We included 381 couples screened for SCF; 65 underwent ICSI cycles with donor oocytes; of these, 46 underwent a previous ICSI cycle with their own oocytes. Fertilization, implantation, clinical pregnancy, and delivery rates were compared between above-mentioned groups. A TUNEL assay was used to measure SCF (≥500 spermatozoa were assessed/sample at a 15% threshold). Paired t and Chi-square tests were used to compare ages and clinical outcomes, respectively.

Main results and the role of chance

We included 381 couples (maternal age, 37.8 ± 4.2; paternal age, 41.8 ± 8.2), whose male partners had the following semen parameters: average volume of 2.5 mL, concentration of 25.4x106/mL, 33% motility, and normal morphology of 1.7. Of these, 316 had elevated average DNA fragmentation of 25.5% and utilized their own oocytes in 683 ICSI cycles, resulting in a 67.5% fertilization, 12.2% implantation, 27.9% clinical pregnancy, and a 22.5% ongoing/delivery. Of the 381 couples, 65 underwent ICSI utilizing donor oocytes (SCF of 24.3%) resulting in a significantly higher fertilization (78.4%) (P < 0.00001) and embryo implantation rates (34.2%) (P < 0.0001). Similarly, albeit not statistically significant, the clinical pregnancy and ongoing/delivery rates increased from 27.9% to 37.1% and from 22.5% to 30.0%, respectively.

To further explore the exclusive role of the male gamete in embryo development, we identified a cohort of patients (n = 46), with an elevated average DNA fragmentation of 23.6%, who underwent an ICSI cycle using their own oocytes and a subsequent cycle using donor oocytes. Compared to cycles where couples used their own oocytes, fertilization, embryo implantation, clinical pregnancy, and ongoing/delivery rates rose from 67.5% to 76.6% (P < 0.0001), 2.8% to 24.7% (P < 0.00001), 8.4% to 38.8% (P < 0.0001), and 1.2% to 28.6% (P < 0.00001), respectively.

Limitations, reasons for caution

Although this study attempts to control for a concurrent confounding female factor, it cannot be completely excluded. It is difficult to assess the extent and contribution of the ooplasmic repair mechanisms on the male genome.

Wider implications of the findings

Ooplasmic repair mechanisms of healthy female gametes appear to repair or improve the deleterious impact of sperm DNA fragmentation on ART outcomes.

Trial registration number

not applicable

O-044 ICSI in the lab: from vintage to AI

With the advent of in vitro fertilization (IVF) by Patrick Steptoe and Bob Edwards in the late 70s, the first conception outside of the human body resulted in the birth of Louise Brown. Although a terrific success, limitations of IVF surfaced, represented by the unexpected complete fertilization failure with suboptimal or dysfunctional spermatozoa.

This prompted curiosity toward individual spermatozoa for a deeper understanding of its role aimed at enhancing the interaction between complementary gametes. Techniques were designed to manipulate the oocytes, such as stripping, partially digesting, or cracking the zona pellucida (ZP). These methods were palliative solutions to overcome fertilization failure and were often plagued by polyspermy. As a result, more direct approaches were implemented to overcome the ZP, such as subzonal injection (SUZI) that although more consistent, was still unable to overcome the shortcomings of dysfunctional spermatozoa. This laid the foundation for the utilization of ICSI that, whilst attempted by some investigators, became popular when Gianpiero Palermo serendipitously inserted one spermatozoon into the ooplasm during SUZI. Consistent fertilization then followed by injecting a cohort of oocytes by ICSI in SUZI cycles, and replacement of these embryos led to 4 pregnancies described in the first clinical ICSI report. To minimize oocyte damage, the procedure was further refined by inducing a deep invagination of the oolemma toward the 9 o’clock position, granting higher chances of post-injection survival.

What set apart ICSI from other forms of ART was that any sperm sample, regardless of quality/quantity, would yield fertilization. Indeed, ICSI is the sole insemination method used with epididymal and testicular spermatozoa and has therefore revolutionized fertility treatment of azoospermic men. Indeed, even immotile testicular spermatozoa can still fertilize and yield successful pregnancies, albeit at a lower rate than their motile counterpart. Also, for these semen sources, aggressive sperm immobilization was introduced to enhance sperm membrane permeabilization and grant optimal fertilization results.

Furthermore, ICSI has transformed the field of reproductive medicine by assisting other reproductive techniques, such as testing embryos for single gene defects to reduce the occurence of sperm DNA contamination, or overcoming the cryostress-induced changes of the ZP during cryopreservation allowing the oocyte to be fertilized at a higher rate. Oocyte cryopreservation now empowers women in their reproductive age to ordain their childbearing future.

ICSI has proven to be the ultimate technique to overcome male infertility and has broadened its indication by yielding consistent fertilization and successful pregnancies in most circumstances, ensuring that men have the chance of fathering their own progeny.

To date, ICSI is applied in several countries, and in some, is performed as the preferred/sole insemination method contributing to the birth of millions of babies worldwide. Thus far, no concerning differences have been seen in the health of ICSI versus standard IVF offspring, or even naturally conceived. In fact, it has been currently established that young adults of both genders born through ICSI retain their reproductive health.

Despite its growing popularity, ICSI does not always succeed but still provides an invaluable platform to deepen our knowledge of gamete biology and helps to investigate/overcome some of the most severe and persistent forms of infertility. For example, combined with assisted gamete treatment, ICSI allows couples plagued by sperm-bound oocyte-activation-deficiency to achieve pregnancy.

The need to increase access and curtail costs of reproductive care has led to the testing of automation in ART. This is also occurring with ICSI and to date, different automated modules have been proposed for oocyte denudation, sperm tracking, and robotic ICSI. Concurrently, there has been an interest in experimenting with artificial intelligence in the IVF laboratory to minimize human shortcomings and ensure that the best spermatozoon is chosen.

O-314 Epigenetic Profiling of Seminal Plasma in NOA Men to Predict Successful Testicular Sperm Retrieval

Study question

Can epigenetic profiling of seminal plasma be used to predict successful testicular sperm retrieval for men with non-obstructive azoospermia (NOA)?

Summary answer

Epigenetic screening of cell-free seminal RNA identified gene imbalances in NOA men, with specific correlation to those who failed to yield spermatozoa at testicular biopsy.

What is known already

Although the chance of a successful microdissection testicular sperm extraction (micro-TESE) in men with NOA can be up to 60%, the procedure may still fail to yield spermatozoa. Several factors have been proposed to predict a successful retrieval, including FSH, inhibin B, genetics, and histopathology. Although histopathology would be the most reliable of these to predict successful micro-TESE, it is equally invasive to perform. Indeed, cell-free RNA extracted from testicular biopsy specimens has been shown to be differentially expressed in infertile men according to the origin of their azoospermia, whether obstructive or nonobstructive, and in relation to a normozoospermic control.

Study design, size, duration

Over a 2-year period, we identified men in whom no spermatozoa were identified despite extensive semen analyses conducted by multiple embryologists. These patients, who were negative for Y microdeletion, subsequently underwent micro-TESE. For consenting men, we performed epigenetic analyses on their seminal plasma by RNAseq. Significant differentially expressed gene (DEG) profiles were then assessed and compared according to whether surgical sperm retrieval successfully yielded spermatozoa (+TESE) or not (-TESE).

Participants/materials, setting, methods

RNA was isolated from the ejaculates for RNAseq using a commercially available spin column kit. RNA isolates were sequenced by Illumina HiSeq at 2x150bp. An absolute log2fold change of > 1 and a P-value of < 0.05 was considered significant. DEG profiles were compared within, as well as between, the +TESE and -TESE cohorts in comparison to a donor control.

Main results and the role of chance

All 12 men (37.3±6yrs) had normal peripheral karyotypes. Six (38.0±7yrs) underwent successful testicular sperm retrievals, defining the +TESE cohort. These men exclusively shared 10 significantly imbalanced genes involved in processes such as spermatogenesis (n = 4), sperm function (n = 2), and testis development (n = 1).

For the 6 men (36.6±5 yrs) who underwent testicular sperm retrievals that failed to yield spermatozoa (-TESE), we identified 16 significantly imbalanced genes, exclusively shared by these patients. These genes are mainly involved in spermatogenesis (n = 9), sperm maturation (n = 1), and cell cycle regulation (n = 4).

We then compared the DEG profiles between the +TESE and -TESE cohorts and identified 8 imbalanced genes that were shared among all 12 NOA men.

Of interest, TPTE2 was partially (67%) expressed in patients from the +TESE group, while IGSF11-AS1 was underexpressed in all men from the -TESE group. Both of these genes are implicated in spermatogenic defects and are normally highly expressed in the testis.

Interestingly, we identified a gene (NA) that was solely and specifically underexpressed in all men from the -TESE group, yet simultaneously overexpressed in all men from the +TESE group. NA, which is well known for its role in sialic acid metabolism, is also present on the sperm acrosome.

Limitations, reasons for caution

Using non-invasive RNAseq on the seminal plasma of NOA men, we were able to identify DEGs according to whether spermatozoa were successfully retrieved or had failed retrieval with micro-TESE. Although intriguing, these are preliminary results that should be further validated in a larger study cohort.

Wider implications of the findings

RNAseq identified genes shared within the same prognostic cohort. Moreover, differential expression of some specific genes predicted micro-TESE outcome. This epigenetic assessment, carried out on the ejaculate, can therefore be used as a non-invasive biomarker tool to predict loss of spermatogenesis in NOA men, sparing them from unnecessary surgery.

Trial registration number

N/A

P-112 Utilizing surgical sperm retrieval to improve clinical outcomes for men with high sperm chromatin fragmentation in their ejaculates

Study question

In men with elevated sperm chromatin fragmentation (SCF), can surgical sperm retrieval from the proximal area of the male genital tract improve clinical outcomes?

Summary answer

Spermatozoa retrieved from the epididymis or testes demonstrate higher genomic integrity and are associated with enhanced embryo implantation, clinical pregnancy, and delivery rates.

What is known already

Sperm genomic integrity is a key factor in achieving a successful pregnancy. During spermiogenesis, alteration of DNA topology involving nuclease and ligase mechanisms is required for supercoiling and DNA compaction. If a proper DNA repair mechanism fails during this intricate process, spermatozoa with DNA fragmentation should be picked up by the epididymis and phagocytized. When this mechanism fails, along with the presence of superimposed reactive oxygen species in the male genital tract, spermatozoa with DNA fragmentation may reach the ejaculates. We have previously demonstrated that retrieving spermatozoa directly from the epididymis and testes yields gametes with higher conserved genomic integrity.

Study design, size, duration

In a nine-year timespan, we identified over 1,000 men with high SCF in their ejaculates; 144 patients consented to undergo surgical retrieval of spermatozoa. In a preliminary assessment, their clinical outcomes were compared to those from men with normal SCF (n = 539). Of these men, 53 consented to undergo subsequent ICSI cycles with their female partners using surgically retrieved spermatozoa from the epididymis (n = 15) or testes (n = 38). Fertilization and clinical outcomes were compared.

Participants/materials, setting, methods

Ejaculated, epididymal, and testicular specimens were screened by terminal deoxynucleotidyl dUTP nick-end labeling (TUNEL) to assess SCF using a commercially available kit. A total of 500 spermatozoa/sample were screened with a normal threshold of 15%. Surgical samples from the epididymis and testes were cryopreserved in multiple vials for subsequent ICSI cycles.

Main results and the role of chance

In the preliminary assessment, ICSI outcomes utilizing ejaculated spermatozoa were compared between men with normal (n = 539, 9.3±3%) and abnormal (n = 144, 28.2±13%) SCF. Although fertilization did not differ, implantation (24.1% vs. 7.8%) and clinical pregnancy rates (CPR, 35.8% vs. 14.6%) were significantly impaired (P < 0.001) in men with elevated SCF.

SCF assessment on surgically retrieved spermatozoa revealed a decreasing trend from 28.2±13% in the ejaculate to 16.6±9.2% in the epididymis and 10.1±5.7% in the testes.

A total of 53 men underwent 79 subsequent ICSI cycles using surgically retrieved spermatozoa. Compared to their historical cycles using ejaculates (n = 65), ICSI with surgically retrieved sperm substantially improved implantation (18.8% vs. 2.1%; P < 0.001), CPR (36.5% vs. 5.3%; P < 0.0001), and ongoing/delivery rates (33.8% vs. 4.1%; P < 0.0001).

Among these couples, 15 underwent 21 ICSI cycles utilizing epididymal spermatozoa with a mean SCF of 16.6±9%. Implantation (26.5% vs. 3.7%; P < 0.05), CPR (68.4% vs. 4.2%; P < 0.0001), and ongoing/delivery rates (57.1% vs. 4.2%; P < 0.0001) were significantly improved compared to the historical cycles.

The remaining 38 patients underwent ICSI with testicular spermatozoa with an average SCF of 10.1±6%. Implantation (15.0% vs. 2.6%; P < 0.01), CPR (25.5% vs. 6.1%; P < 0.01), and ongoing/delivery rates (23.6% vs. 3.0%; P < 0.05) were higher when compared to historical cycles.

Limitations, reasons for caution

Although surgically retrieved spermatozoa can be used to enhance clinical outcomes in couples with high SCF, epididymal spermatozoa yielded higher pregnancy rates despite the higher level of SCF in these specimens compared to testicular spermatozoa. This can be explained by the corrective action of the ICSI procedure itself.

Wider implications of the findings

Our study demonstrated that sperm DNA integrity progressively increases through the journey of the male genital tract. In couples with a compromised sperm genome, surgically retrieved spermatozoa can be beneficial. Therefore, assessing SCF might be used a routine tool to evaluate the male gamete.

Trial registration number

N/A

P-270 Assisted gamete treatment to pinpoint acquired meiotic maturity and overcome oocyte activation deficiency contributed by both gametes

Study question

How can we treat couples with complete and persistent fertilization failure with ICSI linked to a combination of oocyte- and sperm-related oocyte activation deficiency (OAD)?

Summary answer

By targeting spindle presence, we optimized oocyte response to chemical activation and enhanced fertilization. Genomic assessment confirmed gamete contribution.

What is known already

Total fertilization failure occurs in 1-3% of all intracytoplasmic sperm injection (ICSI) cases. In sperm-factor OAD, the lack of phospholipase C zeta (PLCζ) prevents the spermatozoon from initiating downstream calcium oscillation in the oocyte. In these cases, assisted gamete treatment (AGT), which exposes gametes to calcium ionophore, has been adopted to artificially trigger the influx of calcium ions and has been shown to effectively improve fertilization. However, AGT is limited to triggering an intracytoplasmic calcium influx and still requires optimal ooplasmic maturity.

Study design, size, duration

Over the past 17 months, we identified couples with compromised PLCζ and reported persistent fertilization failure with ICSI despite AGT treatment. We then devised a treatment plan comprising an extended in vitro culture (IVC) to pinpoint meiotic oocyte maturity confirmed by the presence of a meiotic II spindle and followed by AGT post-ICSI. Genomic assessment was also carried out.

Participants/materials, setting, methods

Two couples with recurrent and total fertilization failure even after AGT were included. PLCζ expression was assessed using immunofluorescence on ≥ 200 cells/specimen with a 30% threshold. In the follow-up cycles, IVC was extended for at least 8 hours between retrieval and ICSI. Metaphase II spindles were visualized by Oosight®. AGT was performed by exposing both spermatozoa and oocytes to calcium ionophore. NGS was performed on spermatozoa to identify gene mutations involved in fertilization.

Main results and the role of chance

We identified 2 couples (couple A: 37-year-old female, 39-year-old male; couple B: 32-year-old female, 33-year-old male) with the following semen parameters: average volume of 2.6 ml, concentration of 82.0x106/ml, 44% motility, and normal morphology of 3%. The oocyte maturation rate was 76.3% (45/59) but resulted in zero fertilized out of a total of 45 MII oocytes injected. In-house PLCζ assessment revealed a deficiency of oocyte activation factor at 12.9%. AGT treatment alone failed to enhance fertilization on a subsequent cycle, resulting in 0% (0/8) and 5.6% (1/18) fertilization rates for couples A and B, respectively. Couple A then underwent 3 ICSI cycles with extended IVC and AGT; upon examination of nuclear maturity, 91.4% (32/35) of oocytes displayed normal metaphase II spindle and achieved an overall fertilization rate of 43.8% (14/32). To date, 12 blastocysts were cryopreserved. In couple B, 27 oocytes out of 34 retrieved presented normal metaphase II spindles after extended IVC; ICSI with AGT yielded a fertilization rate of 63.0% (17/27). All 17 zygotes were cryopreserved. Overall, our treatment improved fertilization to an overall rate of 52.5% (31/59, P  <0.00001). Genomic assessment of spermatozoa identified gene mutations involved in fertilization (ADAM15, ADAM30) and calcium channel activity (CATSPER1).

Limitations, reasons for caution

Assisted gamete treatment can enhance fertilization in cases of deficiency in PLCζ. However, chemical activation requires a responsive ooplasm that has reached meiotic maturity. These rare cases require precise diagnoses and tailored treatment techniques to address each aspect of sperm- and/or oocyte-factor OAD.

Wider implications of the findings

Our study has demonstrated the usefulness of extended IVC by targeting spindle presence to enhance chemical responses to AGT. Our findings show that although calcium ionophore can trigger the release of intracellular calcium and allow fertilization, a fully mature ooplasm is required.

Trial registration number

N/A

Altered Metabolism of the Microbiota-Gut-Brain Axis Is Linked With Comorbid Anxiety in Fecal Recipient Mice of Myasthenia Gravis

Myasthenia gravis (MG) comorbid anxiety seriously affects the progress of MG. However, the exact relationship remains poorly understood. Recently, our preliminary study has revealed that intestinal microbe disturbance is closely related to MG. Therefore, further exploration of whether the microbiome is involved in MG comorbid anxiety is warranted. In this study, gas chromatography-mass spectrometry metabolomics analysis was used to characterize the metabotype of feces, serum, and three brain regions involved in emotion (i.e., the prefrontal cortex, hippocampus, and striatum), which were obtained from mice that were colonized with fecal microbiota from patients with MG (MMb), healthy individuals (HMb), or co-colonization of both patients and healthy individuals (CMb). Functional enrichment analysis was used to explore the correlation between the “microbiota–gut–brain” (MGB) axis and anxiety-like behavior. The behavioral test showed that female MMb exhibited anxiety-like behavior, which could be reversed by co-colonization. Moreover, metabolic characterization analysis of the MGB axis showed that the metabotype of gut-brain communication was significantly different between MMb and HMb, and 146 differential metabolites were jointly identified. Among these, 44 metabolites in feces; 12 metabolites in serum; 7 metabolites in hippocampus; 2 metabolites in prefrontal cortex; and 6 metabolites in striatum were reversed by co-colonization. Furthermore, the reversed gut microbiota mainly belonged to bacteroides and firmicutes, which were highly correlated with the reversed metabolites within the MGB axis. Among three emotional brain regions, hippocampus was more affected. Therefore, disturbances in gut microbiota may be involved in the progress of anxiety-like behavior in MG due to the MGB axis.

Effect of Akt activation on apoptosis-related gene expression in the crop tissues of male and female pigeons (Columba livia)

The current study investigated whether the expression of apoptosis genes in the pigeon crops was affected by the Akt signaling pathway during crop milk formation. First, 78 pairs of adult White King pigeons were randomly assigned to 7 groups, and the expression of apoptosis-related genes and Akt signaling pathway-related proteins in the crop tissues during different breeding stages were examined. The results showed that the mRNA levels of Bak, caspase-3, caspase-6, and caspase-9 in female crops all increased and reached their highest levels at d 17 of incubation (I17). In male crops, the levels of caspase-3 and caspase-9 gene expression peaked at d 1 of chick rearing (R1). The lowest level of Bcl-2 gene expression in females was observed at I17. The expression ratios of p-Akt (Ser473)/Akt and p-Akt (Thr308)/Akt in male crops decreased to their minimum at R1, while it was observed at d 7 of chick rearing (R7) in females. Second, 36 pairs of adult pigeons were divided into 3 groups and were subjected to SC79 injections with dosages of 0, 0.02, or 0.04 mg/kg bodyweight. The SC79 injections resulted in a considerable decrease in growth performance of pigeon squabs. In male crops, the expression ratios of p-Akt (Ser473)/Akt and p-Akt (Thr308)/Akt were significantly elevated in the 0.02 mg/kg SC79 group, while in female crops, they were higher in the 0.04 mg/kg SC79 group (P < 0.05). The SC79 injection inhibited the gene expression of Bak in female crops, but enhanced the gene expression of Bcl-2 in both male and female crops. In the 0.04 mg/kg SC79 group, a 50.7 to 75.7% decrease was observed in the expression of caspase-3, caspase-6, and caspase-9 in male and female pigeon crops. Expression of the caspase-8 gene and total Akt protein in pigeon crops was not changed in different breeding stages or after SC79 injection. In conclusion, the expression of genes related to mitochondria-dependent apoptosis can be regulated by the Akt signaling pathway, which may play a potential role in pigeon milk formation.

O-206 Meiotic segregation analysis for reciprocal translocation carriers: Assessment of factors influencing meiotic segregation patterns

Study question

To analyze factors that could influence meiotic segregation patterns for reciprocal translocation carriers.

Summary answer

Involvement of an Acr-ch, female gender, and lower TAR1 (ratio of translocated segment 1 over the chromosome arm) were independent risk factors for alternate segregation.

What is known already

Reciprocal translocation is one of the more common structural rearrangements of chromosomes, which is associated with reproductive risks, such as infertility, spontaneous abortion and the delivery of babies with mental retardation or developmental delay. Extensive studies on meiotic segregation patterns of sperm, blastomere, and blastocysts have identified several factors that may influence the generation of unbalanced rearrangement of reciprocal translocations, including carrier’s gender and age, location of breakpoints, chromosome type, and the quadrivalent structure. However, some results are controversial.

Study design, size, duration

A retrospective study from October 2013 to December 2019, a total of 10846 blastocysts originating from 2871 oocyte retrieval cycles from 2253 couples with one of the partners carrying reciprocal were investigated. The mean maternal age was 29.97±4 years (20 –47years).

Participants/materials, setting, methods

Trophectoderm biopsy of blastocysts was performed on the 5th or 6th day of development. Whole genome amplification (WGA) was performed on all samples, and the WGA was analyzed with SNP array or NGS. Segregation patterns of quadrivalent in 10846 blastocysts were analyzed. Risk factors for segregation patterns were explored through analyzing carriers’ demographic and cytogenetic characteristics using multivariate generalized linear mixed models (GLMMs).

Main results and the role of chance

The percentage of normal/balanced blastocysts was 34.3%, and 2:2 segregation was observed in 90.0% of blastocysts. Increased TAR1 (the ratio of translocated segment 1 over the chromosome arm) was noted as an independent protective factor for the proportion of alternate segregation (P = 0.004). The female gender and involvement of an Acr-ch were found independent risk factors for alternate segregation (P &lt; 0.001). A higher TAR1 reduced the risk of adjacent-1 segregation; longer translocated segment and female gender increased the risk of adjacent-2 segregation (P = 0.009 and P &lt; 0.001, respectively). Female gender and involvement of an Acr-ch enhanced the risk of 3:1 segregation (P &lt; 0.001 and P = 0.012, respectively).

Limitations, reasons for caution

About 1400 blastocysts were not diagnosed in the 2871 cycles, which might cause bias in the results. Secondly, the interchromosomal effect of reciprocal translocations was not analyzed in this study.

Wider implications of the findings

In conclusion, a carrier’s gender, involvement of an Acr-ch, and location of breakpoints may influence the segregation patterns. Besides, involvement of an Acr-ch, female gender, and lower TAR1 are independent risk factors for alternate segregation. These results may provide more appropriate genetic counseling for couples with balanced translocation.

Trial registration number

no

P-805 Artificial oocytes: from somatic cells to fertile pups

Study question

We analyzed the efficacy of generating artificial oocytes using somatic cells (SCs) from two mouse strains (B6D2F1 and FVB) and followed their full pre-/post-implantation development.

Summary answer

While artificial oocytes generated from the new strain (FVB) had higher fertilization rates, those from the standard strain (B6D2F1) provided expanded blastocysts and fertile pups.

What is known already

B6D2F1 is a popular hybrid mouse strain for cloning and transgenic creation due to its geno-/pheno-typic uniformity and high oocyte yield and quality. Indeed, B6D2F1 oocytes have a distinct metaphase II (MII) spindle complex, making them an ideal candidate to generate ooplasts used in SC nuclear transfer (SCNT). However, because they lack genetic variance, they are less suitable for reciprocal SCNT studies. In contrast, FVB mice have single nucleotide polymorphisms and indels on each chromosome that can aid in tracing the pedigree of progeny.

Study design, size, duration

A total of 10 experiments were performed over the course of 3 months, using 30 stimulated mice. SCs were retrieved from cumulus oophorus harvested from FVB and B6D2F1 mice. SCs from both strains were injected into enucleated MII B6D2F1 oocytes. Unmanipulated B6D2F1 oocytes were piezo-ICSI inseminated, serving as controls. The occurrence of haploidization, fertilization, and full preimplantation development was compared. Some blastocysts were transferred into pseudo-pregnant CD-1 mice to obtain offspring.

Participants/materials, setting, methods

Oocyte enucleation was performed under Oosight™ visualization and cytochalasin B exposure. An FVB or B6D2F1 SC was transferred into the perivitelline space of the ooplast with Sendai virus to promote fusion. Haploidization was monitored by pseudo-meiotic spindle formation followed by extrusion of a pseudo-polar body after insemination. Conceptuses were cultured in a time-lapse imaging system, with piezo-ICSI controls. Expanded blastocysts were transferred into uterine horns of pseudo-pregnant mice. Offspring were mated to test their fertility.

Main results and the role of chance

FVB (n = 278) and B6D2F1 (n = 905) SCs at G0 phase, with a diameter &lt;10 mm, were chosen for SCNT and transferred into enucleated B6D2F1 ooplasts. Enucleation of 1,212 oocytes yielded a survival rate of 97.6%. Both FVB and B6D2F1 SCNT resulted in similar survival rates of 100% and 98.5%, respectively. Successful haploidization, determined by the presence of a pseudo-meiotic spindle 2 hours after SCNT, was also comparable, with 59.9% of FVB and 63.7% of B6D2F1. Survival after piezo-ICSI was also comparable between FVB- and B6D2F1-reconstituted oocytes, with rates of 64.3% and 60.3%, respectively, albeit lower than the control (75.2%, P&lt;0.00001). FVB embryos fertilized at a rate of 88.7%, comparable to the control zygotes at 85.8%, while B6D2F1 conceptuses demonstrated a lower fertilization rate (70.8%, P &lt; 0.00001). Blastulation of FVB- and B6D2F1-derived embryos was 15.1% and 24.0%, respectively, while the control was 80.7% (P&lt;0.00001). Whole-genome karyotyping of 9 B6D2F1-derived blastocysts confirmed 5 of the samples to be euploid. FVB blastocysts (N = 8) and B6D2F1 blastocysts (N = 81) were transferred into pseudo-pregnant mice, resulting in 3 fertile offspring only from the B6D2F1 conceptuses.

Limitations, reasons for caution

This is still a limited number of observations, and pups were delivered only from the B6D2F1 strain. The utilization of a strain with higher genetic variance may help facilitate offspring fingerprinting.

Wider implications of the findings

This study demonstrates the ability to generate artificial genotyped conceptuses, yielding live offspring. The identification of a feasible donor cell, together with optimization of cell cycle stage and standardization of post-implantation development, will help promote this technique for human reproduction in couples with age-related infertility or poor ovarian reserve.

Trial registration number

N/A

P–119 The correlation between sperm chromatin fragmentation and intrauterine insemination outcome

Study question

Does sperm genomic integrity affect the intrauterine insemination (IUI) outcomes in couples with unexplained infertility and young maternal age?

Summary answer

Spermatozoa with higher genomic integrity are correlated with higher clinical pregnancy rates in couples with unexplained infertility undergoing IUI.

What is known already

It is known that elevated sperm chromatin fragmentation (SCF) on the male gamete affects embryo development and implantation. This is particularly relevant in IVF as well as programmed intercourse and IUI. By complementing the standard semen analysis with an SCF assay, we can assess the competence of the male gamete and its ability to generate euploid embryos and healthy offspring. Elevated SCF has been used as a way to identify subtle male factor infertility in couples undergoing IUI with poor pregnancy outcomes in order to plan for further treatments.

Study design, size, duration

This is a retrospective cohort study of IUI outcomes of couples with young maternal age and a negative infertility workup treated at our center from 2016–2020. Terminal deoxynucleotidyl dUTP transferase nick-end labeling (TUNEL) assay was used to assess sperm genomic integrity. Couples were grouped based on SCF level: normal (≤15%) or abnormal (&gt;15%). Rates of clinical pregnancy, defined as the presence of a fetal heartbeat, were compared between the groups following IUI.

Participants/materials, setting, methods

A total of 189 consenting couples, in which the female partner had a normal uterine cavity and patent fallopian tubes, underwent 454 IUI attempts. Only women ≤37 years old were included to control for age-related confounding factors. At least 500 spermatozoa were assessed per patient, and a threshold of ≤ 15% was considered normal. Women were either untreated for natural cycle IUI or stimulated with clomiphene citrate, gonadotropins, or Letrozole.

Main results and the role of chance

A total of 454 IUI cycles were reported at our center; 302 of these were carried out in 132 couples in which the male partner had normal SCF averaged at 9.29%. The average maternal age was 34.1±3 years, and the average paternal age was 37.1±5 years. These men had the following semen parameters: a concentration of 46.2±5x106/mL, 43.8±3% motility, and an average SCF of 9.3±3%. There were 45 documented clinical pregnancies (45/302, 14.9%) as confirmed by the presence of at least one fetal heartbeat detected by ultrasound; 26 delivered, 9 are ongoing, 5 were spontaneous abortions, and 5 were lost to follow-up. A total of 57 couples in which the male partner (37.2±5.9 years) had abnormal SCF underwent 152 IUI cycles (maternal age, 34.0±2.7 years). The men had the following semen parameters: an average SCF of 23.8±10 (p &lt; 0.0001), a concentration of 26.0±10 x106/ml, and 40.1±4% motility. These IUI attempts yielded a clinical pregnancy rate of only 4.6% (7/152; P &lt; 0.0001); 4 delivered and 3 were spontaneous abortions.

Limitations, reasons for caution

This study is a retrospective cohort analysis of a relatively small number of patients. Furthermore, most patients were screened for SCF due to at least one prior IUI failure. A prospective, randomized trial, in which men are concurrently screened for SCF levels at the first IUI attempt, would be ideal.

Wider implications of the findings: Assessment of SCF at the initial male infertility screening can be a useful tool to investigate the competence of the male gamete. Screening couples with idiopathic infertility for a subtle male factor would guide those with higher SCF toward alternative reproductive treatments to avoid unnecessary IUI treatments.

Trial registration number

Not applicable

P–804 Morphokinetic development by time-lapse imaging of conceptuses generated from artificial oocytes

Study question

What are the ideal culture conditions to enhance full preimplantation development of embryos generated by FVB somatic cell haploidization (SCH) in the mouse model?

Summary answer

The presence of a histone deacetylase inhibitor yielded the best morphokinetic development of expanded blastocysts generated by FVB SCH, comparable to control blastocysts.

What is known already

Various culture conditions and medium supplements have been proposed to promote preimplantation development of embryos generated by SCH, including supplementation with trichostatin A (TSA), fasudil, scriptaid, and RAD–51 stimulatory compound–1 (RS–1). TSA and scriptaid, both histone-deacetylase inhibitors, have been found to improve embryo development following nuclear transfer by enhancing histone acetylation and cellular reprogramming. Additionally, fasudil is a Rho-associated kinase inhibitor that has been shown to reduce apoptosis and promote cell proliferation. Finally, RS–1 stimulates RAD51 activity, which promotes the repair of DNA damage and increases the efficacy of somatic cell reprogramming.

Study design, size, duration

B6D2F1 mouse metaphase II (MII) oocytes underwent enucleation and nuclear transfer, or were ICSI inseminated serving as controls. Reconstituted oocytes showing development of a meiotic-like spindle demonstrated successful SCH, and were ICSI inseminated. SCH conceptuses were cultured in one of three groups: KSOM, KSOM supplemented with TSA (TSA), or KSOM supplemented with fasudil, scriptaid, and RS–1 (Cocktail). ICSI controls (ICSIC) were cultured in KSOM medium. Fertilization and full preimplantation development were compared among all groups.

Participants/materials, setting, methods

Ooplasts were generated from MII oocytes by removing spindle complexes under OosightÔ visualization and cytochalasin B exposure. A single FVB mouse cumulus cell was transferred into the perivitelline space and fused with the ooplast, facilitated by Sendai virus. Reconstructed oocytes with novel pseudo-meiotic spindles underwent piezo-ICSI and were cultured in different media conditions in a time-lapse imaging system up to 96h. TSA and Cocktail embryos had media changed to regular KSOM 10 hours after insemination.

Main results and the role of chance

A total of 274 B6D2F1 MII oocytes were enucleated, resulting in a 95.9% survival rate. All ooplasts survived nuclear transfer and 62.1% successfully haploidized after 2 hours. ICSIC and reconstituted SCH oocytes survived piezo-ICSI at rates of 81.5% and 57.0%, respectively (P &lt; 0.01). SCH embryos were then allocated into KSOM, TSA supplied, and Cocktail media. Fertilization rates for ICSIC, KSOM, and TSA embryos were 92.4%, 90.7%, and 94.4%, respectively, while the rate for embryos cultured in Cocktail was only 71.9% (P &lt; 0.03). While embryos cultured in Cocktail had a comparable 2-cell timing to ICSIC, embryos in TSA reached developmental milestones with a closer timing to the ICSIC, having minor delays at the 3-, 4-, and 6-cell stages (P &lt; 0.05). KSOM- and Cocktail-cultured embryos were delayed at most of the stages (P &lt; 0.01), except for the two-pronuclei appearance. Although the TSA group displayed the best embryo developmental pattern, the final rate of blastocyst development was somewhat homogeneous with rates of 15.4%, 23.5%, and 13.0% for the KSOM, TSA, and Cocktail groups, respectively (P &lt; 0.001), and remarkably lower than the ICSIC (81.6%).

Limitations, reasons for caution

Although live pups have been obtained using BDF cumulus cells, embryos generated by FVB cumulus cells show a remarkably lower blastocyst development, but maintain morphokinetic characteristics similar to ICSIC in the presence of TSA.

Wider implications of the findings: While using different strains to enhance genetic variance, the morphokinetic analysis of preimplantation embryos in ideal culture conditions is paramount to the progress of neogametogenesis. The implementation of this technique may soon help create genotyped oocytes for women with compromised ovarian reserve.

Trial registration number

N/A

P-525 Analysis of segregation patterns of trivalent structure and the effect on genome stability in Robertsonian translocation carriers

Study question

What are the factors that affect the separation pattern of Robertsonian translocation trivalent, and whether the structure of the trivalent affected the chromosome stability?

Summary answer

The meiotic segregation modes can be affected by the carrier’s sex and special chromosome, and a trivalent structure can affect the stability of the genome.

What is known already

Robertson translocation occurs when two proximal acrocentric chromosomes fuse at the centromere, and forms a trivalent structure during meiosis. This structure will affect the fertility of Robertsonian translocation carriers, and may destroy the stability of the genome by affecting the separation of other chromosomes, which is called Inter-Chromosomal Effect (ICE). Previous research have confirmed that the use of PGT in Robertsonian translocation carriers can effectively reduce abortion and increase live birth. But some studies dispute this conclusion and the existence of ICE. However, there is no large data study to verify these controversies.

Study design, size, duration

PGT results of 928 oocyte retrieval cycles in 763 couples(one of the couples is a Robertsonian translocation carrier) were analysied from December 2012 to June 2020. A total of 1492 couples who received PGT-A were collected as control group, and matched according to age and testing time stage. The study was approved by the ethics committee(LL-SC-SG-2006-008 and LL-SC-SG-2014-016).

Participants/materials, setting, methods

Cytogenetic analysis was performed using GTG standard method (trypsin and GiemsaG banding) to analyze the chromosomes of peripheral blood lymphocytes. Blastocysts obtained by standard IVF procedure were biopsied on the 5th or 6th morning after fertilization, and the trophoblast cells were amplified by PicoPLEX whole genome amplification kit (Rubicon Genology) or Repli-g Single Cell Kit(Qiagen). PGT-SR was performed using SNP array or NGS as previously described.

Main results and the role of chance

In this study, a total of 3423 blastocysts from 763 couples were analysed using SNP-array or NGS. Among them, the rate of alternate segregation of male Robertsonian translocation carriers was significantly higher than that in female carriers (82.26% vs 59.96%, P &lt; 0.001), and meiotic segregation modes could be affected by the special chromosome such as 13 in female(P = 0.042) and 15 in male(P = 0.045) involved. A trivalent structure can affect the stability of the genome during mitosis, which is associated with an increase in the propotion of chromosome mosaic compared with the PGT-A control group(1.18% vs 0.53%, P &lt; 0.01). In addition, we found an interesting phenomenon: in the meiotic segregation of female Robertsonian translocation carriers associated with chromosomes 21 and 22, the chromosome 21 or 22 of the two chromosomes involved in translocation are more likely to be abnormal, and according to our results, the effect of chromosome 21 seems to be greater.

Limitations, reasons for caution

(1) Limitations of retrospective analysis; (2) The results are not fully representative of the general population; (3) PGT-A patients always had repeated implantation failure or recurrent aboration, which may cause deviation to the results.

Wider implications of the findings

This study analyzed the influencing factors of the separation patterns of trivalent, and verified the existence of ICE. This suggest that PGT-SR can have a better outcome in patients with Robertsonian translocation, especially in male carriers. These results will provide carrier couple with more appropriate genetic counseling.

Trial registration number

no

P–806 Neogametogenesis via oocyte replication

Study question

Can full preimplantation embryo development be achieved from artificial oocytes created through nuclear transfer of a haploid pseudo-blastomere (HpB) into a recipient ooplast?

Summary answer

It is feasible to replicate the female genome and generate novel sibling oocytes that can yield full preimplantation embryo development, albeit at a reduced rate.

What is known already

A limitation of assisted reproduction is the number of available oocytes for embryo creation. It is feasible to utilize a somatic cell nucleus to construct novel oocytes through a process known as haploidization, in which a reverse meiosis occurs after SCNT. Similarly, producing haploid parthenogenetic constructs can generate HpBs, useful for genetic testing at the pre-fertilization level or for reproduction. It is feasible to use a HpB as a nuclear donor since it has already completed homologue segregation.

Study design, size, duration

This is prospective translational animal model study. Over 6 months, 556 oocytes were manipulated for the experimental group, and 158 control oocytes were employed. B6D2F1 HpBs were used to establish the procedure and acquire expertise. FVB HpBs were subsequently introduced for genetic variance. Experimental and control embryos were cultured in a time-lapse incubator (up to 96h). Cleavage parameters were compared to control. Two-sample T-tests and one-way ANOVA with Bonferroni correction were employed for statistical analysis.

Participants/materials, setting, methods

A cohort of oocytes was harvested from B6D2F1 or FVB superovulated mice and artificially activated by 8% ethanol. At the 8-cell stage, HpBs were exposed to nocodazole. Another cohort of B6D2F1 oocytes was enucleated for recipient ooplasts. HpBs were individually transferred into the perivitelline space of the ooplasts alongside inactivated Sendai virus. After fusion, reconstructed oocytes with spindle development were fertilized by piezo-actuated ICSI using B6D2F1 spermatozoa. Unmanipulated and fertilized B6D2F1 oocytes served as control.

Main results and the role of chance

A total of 158 control oocytes underwent ICSI with a 67.7% survival rate; of these, 65.4% developed to the blastocyst stage. For artificial oocyte activation (AOA), up to 10 oocytes were activated for each experiment, yielding 8 HpBs per activated oocyte. For the experimental group, 556 oocytes underwent enucleation with a 96.4% survival rate. Nuclear transfer of HpBs resulted in a 93.2% survival rate, consistent for those derived from BDF and FVB. Reconstructed oocytes showed appropriate development of a novel pseudo-meoitic spindle at a rate of 63.7% for B6D2F1 HpBs and 75.5% for FVB HpBs, and ICSI yielded a 67.1% and 57.7% survival rate, respectively. The fertilization rate for the reconstructed oocytes was 64%. Control oocytes underwent ICSI with a 67.7% survival rate. When evaluating time-lapse parameters, reconstructed embryos created via blastomere nuclear transfer showed asynchrony compared to controls beginning as early as the stage of pronuclear fading. While the majority of reconstructed embryos arrested at the 4-cell stage, of those that progressed, 11.3% of those using BDF HpBs and 14.6% of those using FVB HpBs developed to the fully expanded blastocyst stage. This corresponds to a total of 23 reconstructed embryos that developed to the morula or blastocyst stage.

Limitations, reasons for caution

While we used single-well embryoscope culture for morphokinetic data collection, group culture is superior to single-embryo culture for mice. Thus, developmental rates may be underestimated by this protocol. Implantation and successful pregnancy are also needed to support the clinical utility of this method in generating gametes.

Wider implications of the findings: For women with diminished ovarian reserve, oocyte yield and age-related aneuploidy are limitations to achieving genotyped offspring. Nuclear transfer of HpB can generate sibling oocytes while maintaining genetic information. This model represents a promising path for expanding oocyte yield, allowing genetic assessment of sibling oocytes, and enhancing chances of procreation.

Trial registration number

none

P–800 Generation of artificial oocytes by two distinct mechanisms

Study question

Are haploid genome replication and somatic cell haploidization feasible mechanisms for generating parentally genotyped oocytes?

Summary answer

Artificial oocytes can be generated by haploid genome replication and somatic cell haploidization. The latter is more efficient and capable of generating live offspring.

What is known already

A low number of mature oocytes is one of the major limitations to treating infertile women who have impaired ovarian reserve. Although it has been proposed that competent oocytes can be created by a phenomenon known as somatic cell haploidization (SCH), its clinical value has yet to be examined due to its poorly understood mechanism. On the other hand, spindle transfer has been clinically applied for mitochondrial replacement therapy. Therefore, we propose to utilize G2-phase haploid pseudo-blastomere (HpB), generated by parthenogenesis, as a nuclear donor to create oocyte replica.

Study design, size, duration

In the past 7 months, individual G0 phase cumulus cells (CCs) were transferred into 1,066 ooplasts for SCH. HpBs obtained from the activation of 80 oocytes were transferred into 464 ooplasts. Both cohorts were ICSI-inseminated and placed in the time lapse for embryo development. Another 379 unmanipulated oocytes were ICSI-inseminated, serving as control. Pre-implantation development was monitored and compared for both neogametogenesis techniques. Fully expanded blastocysts were transferred to obtain live pups.

Participants/materials, setting, methods

CCs were isolated from the cumulus oophorus of B6D2F1 mice. HpBs were obtained via oocyte activation, cultured to the 8-cell stage, and subsequently treated by nocodazole to synchronize at the G2-phase. In two experimental groups, CCs or HpBs were individually transferred into the perivitelline space of the ooplasts with inactivated Sendai virus. Reconstructed oocytes presenting with a pseudo-meiotic spindle were fertilized by piezo-actuated ICSI. Blastocysts were transferred into a pseudo-pregnant CD–1 surrogate to obtain pups.

Main results and the role of chance

A total of 1,769 oocytes underwent enucleation to generate ooplasts, with a survival rate of 97%. Survived ooplasts were allocated to SCH (n = 1,034) and HpB-SCNT (n = 458). To generate HpBs, 80 unmanipulated oocytes were activated; 58 of them progressed to the 8-cell stage and generated 464 HpB for SCNT. For SCH, CCs were selected based on morphology with a diameter &lt;10 micron. Nuclear transfer of CCs and HpB yielded survival rates of 98.6% and 93.2%, respectively. Following SCH and HpB-SCNT, spindle development for SCH and HpB-SCNT was comparable at 63.5% for SCH and 66.7% for HpB-SCNT. The ICSI survival rates for SCH and HpB-SCNT were 58.9% and 64.9%, respectively, but lower than the control at 73.9% (P &lt; 0.001). Fertilization rates for SCH and HpB-SCNT were also comparable at 61.3% and 64.3%, respectively, but lower than the control at 89.6% (P &lt; 0.00001). Full pre-implantation development was achieved for both experimental groups. While the SCH group yielded a development rate of 24.6% (n = 94), the HpB-SCNT group yielded a lower rate at 12.4% (n = 23) (P &lt; 0.001), both lower than the control (71.7%, P &lt; 0.00001); however, the morphokinetics of the embryo development was retained. To date, only 3 live pups were obtained from SCH group.

Limitations, reasons for caution

While these techniques to manufacture oocytes are very new and highly experimental, our findings show a lower blastulation rate for oocytes generated by HpB. Both techniques require refinement and improvement of reliability and consistency before they can be considered a feasible technique for human reproduction.

Wider implications of the findings: The study confirms the potential to create artificial oocytes capable of supporting full pre-implantation development and, in some cases, live pups. If further streamlining of both procedures demonstrates their safety, they may both represent a viable option to generate de novo gametes

Trial registration number

N/A

O-124 Contact-free oocyte denudation in a chip-scale ultrasonic microfluidic device

Study question

To design and test an automated microfluidic device to revolutionize the cumulus-oocyte-complex (COC) denudation procedure for intracytoplasmic sperm injection (ICSI) using murine oocytes.

Summary answer

Oocyte exposure to temperature variation, mechanical stress, and prolonged chemical treatment during denudation was mitigated using our microfluidic device based on surface acoustic waves (SAWs).

What is known already

COC denudation is a prerequisite for many ART procedures such as ICSI. However, this procedure is based on manual pipetting (MP), which lacks standardization and requires experienced embryologists to perform. Inadequate MP may damage oocytes through prolonged enzymatic treatment or high fluidic stresses and may jeopardize gamete competence. The use of microfluidic devices based on porous membranes or microchannels has been adopted by many laboratories for sperm selection. Of these, microchannel devices may also be adapted for denudation with minimal mechanical stress in a controlled microenvironment. However, oocyte manipulation and extraction have proven difficult to achieve.

Study design, size, duration

We developed a novel ultrasonic microfluidic device based on a microwell design manufactured with Polydimethylsiloxane (PDMS). The SAWs were generated by 4 interdigitated transducers (IDTs) arranged in an orthogonally symmetric pattern. A non-toxic dosage of ultrasonic waves, similar to those used in gynecology and obstetrics, was applied. COCs were denuded by induced acoustic streaming and acoustic radiation force. Denudation rate, embryo development, and pregnancy outcomes were assessed and compared to control oocytes denuded by MP.

Participants/materials, setting, methods

For each run, up to 10 individual COCs from super-ovulated B6D2F1 mice were loaded into the microwell alongside diluted hyaluronidase (20 IU/ml) and denuded by 80 or 200 MHz SAWs. Denuded oocytes were fertilized by piezo-actuated ICSI using spermatozoa from the same strain. Pre-implantation embryo development was assessed in a time-lapse incubator for up to 96 h. High-quality blastocysts were transferred to 2.5-dpc pseudo-pregnant CD-1 surrogates. Pregnancy and offspring health were observed.

Main results and the role of chance

Using alternating frequency sweep in a pulse-repetition mode, we swirled the fluid inside the microwell consistently and tumbled COCs inside the microwell to expose them to acoustic steaming-induced drag forces and acoustic radiation force. Using a high-speed camera and particle-tracking technique, we observed that the drag force generated by the SAWs fulfilled the denudation mechanism. Additionally, due to the small attenuation coefficient in water, thermal absorption heating remains minuscule, preventing any thermal-induced damage.

Our device significantly reduced the time and labor of the denudation process. It also yielded proper denudation quality without oocyte loss. To ensure that SAWs do not damage oocytes, 40 oocytes denuded by 80 MHz SAWs, 25 oocytes denuded by 200 MHz SAWs, and 30 oocytes denuded by MP were inseminated by piezo-actuated ICSI. The 80-MHz, 200-MHz, and MP groups yielded comparable post-ICSI survival (82.5% vs. 84.0% vs. 83.3%, respectively), fertilization (80.0% vs. 80.0% vs. 83.3%,respectively), and blastulation rates (72.5% vs. 82.0% vs. 66.7%, respectively). Embryo morphokinetics were also not impacted. After transferring all blastocysts into recipient mice, 8 live births were achieved from the 80-MHz group, while 5 were achieved from the 200-MHz group.

Limitations, reasons for caution

Although PDMS is a popular material due to its high optical transparency and biocompatibility, adverse effects due to gas permeability and small-molecule adsorption cannot be excluded. Large-scale mouse embryo assays should be performed to assess the teratogenicity of PDMS. Operation parameters must be optimized for human COCs in clinical application.

Wider implications of the findings

Adopting widely used ultrasound techniques with emerging SAW technology is a major step toward advancing and standardizing oocyte denudation—a laborious yet delicate procedure. We predict it will be further integrated with AI and miniaturized robotics, modules specialized in gamete assessment, ICSI, and embryo evaluation in the near future.

Trial registration number

‘not applicable’

P–805 Artificial oocytes: from somatic cells to fertile pups

Study question

We analyzed the efficacy of generating artificial oocytes using somatic cells (SCs) from two mouse strains (B6D2F1 and FVB) and followed their full pre-/post-implantation development.

Summary answer

While artificial oocytes generated from the new strain (FVB) had higher fertilization rates, those from the standard strain (B6D2F1) provided expanded blastocysts and fertile pups.

What is known already

B6D2F1 is a popular hybrid mouse strain for cloning and transgenic creation due to its geno-/pheno-typic uniformity and high oocyte yield and quality. Indeed, B6D2F1 oocytes have a distinct metaphase II (MII) spindle complex, making them an ideal candidate to generate ooplasts used in SC nuclear transfer (SCNT). However, because they lack genetic variance, they are less suitable for reciprocal SCNT studies. In contrast, FVB mice have single nucleotide polymorphisms and indels on each chromosome that can aid in tracing the pedigree of progeny.

Study design, size, duration

A total of 10 experiments were performed over the course of 3 months, using 30 stimulated mice. SCs were retrieved from cumulus oophorus harvested from FVB and B6D2F1 mice. SCs from both strains were injected into enucleated MII B6D2F1 oocytes. Unmanipulated B6D2F1 oocytes were piezo-ICSI inseminated, serving as controls. The occurrence of haploidization, fertilization, and full preimplantation development was compared. Some blastocysts were transferred into pseudo-pregnant CD–1 mice to obtain offspring.

Participants/materials, setting, methods

Oocyte enucleation was performed under Oosight™ visualization and cytochalasin B exposure. An FVB or B6D2F1 SC was transferred into the perivitelline space of the ooplast with Sendai virus to promote fusion. Haploidization was monitored by pseudo-meiotic spindle formation followed by extrusion of a pseudo-polar body after insemination. Conceptuses were cultured in a time-lapse imaging system, with piezo-ICSI controls. Expanded blastocysts were transferred into uterine horns of pseudo-pregnant mice. Offspring were mated to test their fertility.

Main results and the role of chance

FVB (n = 278) and B6D2F1 (n = 905) SCs at G0 phase, with a diameter &lt;10 mm, were chosen for SCNT and transferred into enucleated B6D2F1 ooplasts. Enucleation of 1,212 oocytes yielded a survival rate of 97.6%. Both FVB and B6D2F1 SCNT resulted in similar survival rates of 100% and 98.5%, respectively. Successful haploidization, determined by the presence of a pseudo-meiotic spindle 2 hours after SCNT, was also comparable, with 59.9% of FVB and 63.7% of B6D2F1. Survival after piezo-ICSI was also comparable between FVB- and B6D2F1-reconstituted oocytes, with rates of 64.3% and 60.3%, respectively, albeit lower than the control (75.2%, P &lt; 0.00001). FVB embryos fertilized at a rate of 88.7%, comparable to the control zygotes at 85.8%, while B6D2F1 conceptuses demonstrated a lower fertilization rate (70.8%, P &lt; 0.00001). Blastulation of FVB- and B6D2F1-derived embryos was 15.1% and 24.0%, respectively, while the control was 80.7% (P &lt; 0.00001). Whole-genome karyotyping of 9 B6D2F1-derived blastocysts confirmed 5 of the samples to be euploid. FVB blastocysts (N = 8) and B6D2F1 blastocysts (N = 81) were transferred into pseudo-pregnant mice, resulting in 3 fertile offspring only from the B6D2F1 conceptuses.

Limitations, reasons for caution

This is still a limited number of observations, and pups were delivered only from the B6D2F1 strain. The utilization of a strain with higher genetic variance may help facilitate offspring fingerprinting.

Wider implications of the findings: This study demonstrates the ability to generate artificial genotyped conceptuses, yielding live offspring. The identification of a feasible donor cell, together with optimization of cell cycle stage and standardization of post-implantation development, will help promote this technique for human reproduction in couples with age-related infertility or poor ovarian reserve.

Trial registration number

N/A

O-094 Utilization of ultrastructural analysis and genomics of spermatozoa to better characterize subtle forms of male factor infertility

Study question

Can sequencing the sperm genome provide insight into the various forms of male factor infertility caused by sperm organelle ultrastructural defects?

Summary answer

A comprehensive genomic assessment of spermatozoal DNA is able to identify genetic causes of ultrastructural defects visualized by transmission electron microscopy (TEM).

What is known already

To evaluate a man’s reproductive potential, a conventional semen analysis through the assessment of concentration, motility, and morphology can indicate the proficiency of male gametes. Among those, conventional morphology assay can only provide indirect information on the different components of the sperm cell. The assessment of nanoscopic details such as chromatin, centriolar, mitochondrial, and axonemal components can only be observed by TEM. Indeed, TEM has been used to identify defects in the acrosome, chromatin compaction, and axonemal/periaxonemal structures. Furthermore, exome sequencing of spermatozoal DNA may identify novel causes and candidate genes for these ultrastructural defects.

Study design, size, duration

In the past 2 years, 20 men with history of fertilization failure or severe astheno-/terato-zoospermia were selected for TEM analysis of their spermatozoa, while 3 fertile men served as controls. Sperm head characteristics, intactness of fibrous sheath, and axonemal/periaxonemal structure were examined by diagnostic TEM. For consenting patients, NGS assessment was concurrently performed to identify mutations responsible for the structural abnormalities identified by TEM.

Participants/materials, setting, methods

TEM was performed on the ejaculates of 20 infertile patients and 3 fertile controls. Post-centrifugation cell pellets were resuspended, fixed, and dehydrated to be infiltrated and embedded onto the resin. Fixed specimens were sliced by ultramicrotome to 100-nm sections, then viewed by JEOL-1400 electron microscope at 300,000X magnification. At least 100 spermatozoa were evaluated by TEM. For consenting patients, DNA was extracted and amplified from at least 500 spermatozoa for concurrent NGS analysis.

Main results and the role of chance

Four types of sperm ultrastructural defects were observed, including globozoospermia, dysplasia of fibrous sheath (DFS), proximal centriole defect, and primary ciliary dyskinesia (PCD). One combined case of globozoospermia and DFS was identified. In globozoospermic patients (n = 13), 97-100% of the spermatozoa displayed characteristic spherical heads with absence of acrosomes, dispersed chromatin, and perinuclear theca deformities. Centrosomal and axonemal structures were conserved. NGS identified gene deletions (DPY19L, PICK1, SPATA16) directly related to the globozoospermic phenotype. In patients with DFS (n = 4), complete absence of flagellum was observed in 90-100% of spermatozoa. These defective gametes also displayed mitochondria disorganization, microtubular deformities, and cytoplasmic residues containing coiled flagellum with deformed capitulum within the plasma membrane. Contrary to the globozoospermia, acrosomes and nuclei appeared normal, indicating incomplete late spermiogenesis. Indeed, NGS confirmed gene deletions involved in flagellar development/function (AKAP4, SPAG16, CATSPER1). For the patient with proximal centriole defect (n = 1), sperm nucleus, fibrous sheath, and flagellar structure were conserved. However, 90% of proximal centrioles assessed exhibited microtubular disorganization, confirmed by ODF2 mutation per NGS. In the PCD patient (n = 1), chaotic flagellar microtubule arrangement and absence of outer dynein arms were prevalent in 90% of axonemal cross-sections examined, which was explained by a DNAH5 gene deletion.

Limitations, reasons for caution

While TEM can overcome the limitations of conventional semen analysis by providing direct visualization of the inner organelle arrangement of spermatozoa to accurately diagnose rare sperm pathologies, it is not routinely applied in clinics due to its high cost and technical specifications. Therefore, confirmatory NGS can provide additional diagnostic value.

Wider implications of the findings

Ultrastructural analysis with a concurrent genomic assessment characterized phenotypes and genotypes of rare sperm pathologies in infertile men. The utilization of TEM, corroborated by genomic assay, is therefore crucial for clinical and translational reproductive medicine to better characterize male factor infertility.

Trial registration number

N/A

P–120 Selecting spermatozoa with the highest genomic integrity in order to enhance clinical outcomes in men with high DNA fragmentation levels

Study question

What are the best methods of selecting spermatozoa with the highest genomic integrity in order to improve embryo implantation and term pregnancy rates with ICSI?

Summary answer

Testicular or ejaculate spermatozoa isolated by microfluidic sperm selection (MFSS) were characterized by superior genomic integrity with improved clinical pregnancy and delivery rates.

What is known already

In couples with unexplained infertility, a subtle male factor can often be identified. Both single-strand (ss) and double-strand (ds) DNA nicks and breaks hinder the ability of the male gamete to support embryonic development. Surgical retrieval of spermatozoa from the proximal male genital tract can prevent their exposure to oxidative stress. Moreover, use of membrane-based microfluidics chips has been shown to allow for selection of the most progressively motile spermatozoa with higher genomic integrity.

Study design, size, duration

Over the course of 48 months, 86 consenting men presenting with high sperm chromatin fragmentation (SCF) in their ejaculate with prior ART failure underwent a subsequent cycle with specimens retrieved by testicular biopsy or ejaculate processed by MFSS. A concurrent TUNEL assay was performed on samples collected or selected by each method. Sperm specimens of both origins were utilized for ICSI cycles. Semen parameters, chromatin integrity, and pregnancy outcomes were compared between the two methods.

Participants/materials, setting, methods

Fresh ejaculates from consenting men were collected for standard semen analysis (WHO 2010). Testicular biopsy and MFSS were used to isolate spermatozoa with a higher genomic integrity after previous ART failure. SCF was assessed by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) on at least 500 spermatozoa under a fluorescent microscope with a threshold of ≥ 15%. MFSS was carried out by Zymot® chips. ICSI was performed in the standard fashion.

Main results and the role of chance

A total of 86 men (36.5±5 years) had the following semen parameters: volume of 2.6 ±1mL, concentration of 27.0±33 x 106/mL, 35.6±15% motility, and high SCF (24.1±10%). They underwent 146 ICSI cycles with their partners (maternal age, 33.7±3) resulting in a high incidence of pregnancy loss (100%; 13/13). Of those who failed to conceive, 22 couples used surgically retrieved spermatozoa (SRS) with a concentration of 1.8 ± 4 x 106/mL (P &lt; 0.01), 5.0±11% motility (P &lt; 0.01), and an SCF of 12.6 ± 6% (P &lt; 0.0001). SRS was used in 37 ICSI cycles, yielding a fertilization rate of 61.6% (204/331, P &lt; 0.01), an implantation rate of 10.6% (9/85, P &lt; 0.01), a CPR of 23.5% (8/34, P &lt; 0.01), and a delivery rate of 17.6% (6/34, P &lt; 0.01). Another 24 couples underwent ICSI cycles with ejaculated spermatozoa processed by MFSS with a concentration of 1.8±3 x 106/mL (P &lt; 0.01), but an increased motility of 99±1% (P &lt; 0.01) and an SCF of 1.2 ±1%, lower than both the raw and testicular specimens (P &lt; 0.0001). MFSS-processed specimens resulted in a fertilization rate of 76% (335/441, P &lt; 0.01), an implantation rate of 26.3% (15/57, P &lt; 0.05), and a CPR of 67.9% (19/28, P &lt; 0.01), of which 15 patients delivered and 2 pregnancies are ongoing (89.5%; P &lt; 0.01).

Limitations, reasons for caution

This is a preliminary study on a small number of subjects. A randomized prospective study conducted on a larger cohort would be required to confirm our findings.

Wider implications of the findings: SCF severely affects pregnancy by impairing embryonic development, consequently promoting implantation failure. While retrieving spermatozoa from the germinal epithelium is a viable option, MFSS provides an alternative. Although MFSS requires an adequate number of sperm with good kinetic characteristics, it provides a more palatable option, reducing surgical risk and costs.

Trial registration number

Not applicable

P–525 Analysis of segregation patterns of trivalent structure and the effect on genome stability in Robertsonian translocation carriers

Study question

What are the factors that affect the separation pattern of Robertsonian translocation trivalent, and whether the structure of the trivalent affected the chromosome stability?

Summary answer

The meiotic segregation modes can be affected by the carrier’s sex and special chromosome, and a trivalent structure can affect the stability of the genome.

What is known already

Robertson translocation occurs when two proximal acrocentric chromosomes fuse at the centromere, and forms a trivalent structure during meiosis. This structure will affect the fertility of Robertsonian translocation carriers, and may destroy the stability of the genome by affecting the separation of other chromosomes, which is called Inter-Chromosomal Effect (ICE). Previous research have confirmed that the use of PGT in Robertsonian translocation carriers can effectively reduce abortion and increase live birth. But some studies dispute this conclusion and the existence of ICE. However, there is no large data study to verify these controversies.

Study design, size, duration

PGT results of 928 oocyte retrieval cycles in 763 couples(one of the couples is a Robertsonian translocation carrier) were analysied from December 2012 to June 2020. A total of 1492 couples who received PGT-A were collected as control group, and matched according to age and testing time stage. The study was approved by the ethics committee(LL-SC-SG–2006–008 and LL-SC-SG–2014–016).

Participants/materials, setting, methods

Cytogenetic analysis was performed using GTG standard method (trypsin and GiemsaG banding) to analyze the chromosomes of peripheral blood lymphocytes. Blastocysts obtained by standard IVF procedure were biopsied on the 5th or 6th morning after fertilization, and the trophoblast cells were amplified by PicoPLEX whole genome amplification kit (Rubicon Genology) or Repli-g Single Cell Kit(Qiagen). PGT-SR was performed using SNP array or NGS as previously described.

Main results and the role of chance

In this study, a total of 3423 blastocysts from 763 couples were analysed using SNP-array or NGS. Among them, the rate of alternate segregation of male Robertsonian translocation carriers was significantly higher than that in female carriers (82.26% vs 59.96%, P &lt; 0.001), and meiotic segregation modes could be affected by the special chromosome such as 13 in female(P = 0.042) and 15 in male(P = 0.045) involved. A trivalent structure can affect the stability of the genome during mitosis, which is associated with an increase in the propotion of chromosome mosaic compared with the PGT-A control group(1.18% vs 0.53%, P &lt; 0.01). In addition, we found an interesting phenomenon: in the meiotic segregation of female Robertsonian translocation carriers associated with chromosomes 21 and 22, the chromosome 21 or 22 of the two chromosomes involved in translocation are more likely to be abnormal, and according to our results, the effect of chromosome 21 seems to be greater.

Limitations, reasons for caution

(1) Limitations of retrospective analysis; (2) The results are not fully representative of the general population; (3) PGT-A patients always had repeated implantation failure or recurrent aboration, which may cause deviation to the results.

Wider implications of the findings: This study analyzed the influencing factors of the separation patterns of trivalent, and verified the existence of ICE. This suggest that PGT-SR can have a better outcome in patients with Robertsonian translocation, especially in male carriers. These results will provide carrier couple with more appropriate genetic counseling.

Trial registration number

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Heterotrimeric G protein signalling in plant biotic and abiotic stress response

Heterotrimeric G proteins act as molecular switches to participate in transmitting various stimuli signals from outside of cells. G proteins have three subunits, Gα, Gβ and Gγ, which function mutually to modulate many biological processes in plants, including plant growth and development, as well as biotic and abiotic stress responses. In plants, the number of Gγ subunits is larger than that of the α and β subunits. Based on recent breakthroughs in studies of plant G protein signal perception, transduction and downstream effectors, this review summarizes and analyses the connections between different subunits and the interactions of G proteins with other signalling pathways, especially in plant biotic and abiotic stress responses. Based on current progress and unresolved questions in the field, we also suggest future research directions on G proteins in plants.

Effects of incubation and chick rearing on intestinal morphology, digestive enzyme activities, and mRNA expression of nutrient transporter genes in the pigeon (Columba livia) under artificial farming conditions

The present study investigated the changes in morphology, enzyme activities in the pancreas and mucosa, and nutrient transporter gene expression in the duodenum and jejunum in male and female pigeons during the incubation and chick-rearing periods. Forty-two pairs of White King pigeons with 2 fertile eggs per pair were randomly divided into 7 groups by different breeding stages. The crypt depth of the duodenum and jejunum reached the peak at day 1 (R1) and day 7 (R7) of chick rearing, respectively. The jejunum surface area increased to a maximum value at R1. Amylase activity in the pancreas decreased to the lowest value at R1, whereas trypsin and lipase activities peaked at 17 D of incubation (I17) and R7, respectively. In male pigeons, mucosal Na⁺-K⁺-ATPase activity in the duodenum and jejunum was the highest at R15 and it was at I17 in female pigeons. Jejunum sucrose activity in female pigeons was higher at I4 than that at I17 (P < 0.05). The gene expression of FAT/CD36 and I-FABP in the duodenum gradually increased and then declined in the late chick-rearing period. SGLT1 in the jejunum decreased to a lower level at I17 and R25 in male pigeons (P < 0.05). GLUT2 expression in female duodenum and male jejunum decreased to a lower value at I17 compared with that at R15 (P < 0.05). In the late of incubation (from I10 to I17), expression of duodenum CAT1, B⁰AT1, and PepT1 and jejunum CAT1, ASCT1, and PepT1 in female pigeons was significantly reduced (P < 0.05), whereas opposite results were found in male jejunum CAT1 and duodenum ASCT1. In conclusion, variations of intestinal morphology, activities of pancreatic and mucosal enzymes, and gene expression of nutrient transporters during incubation and chick-rearing periods, underlying potential changes of digestive and absorptive function and intestinal adaptation with sexual effects, may represent a complicated response to stimuli of different breeding stages.

The profiling of amino acids in crop milk and plasma and mRNA abundance of amino acid transporters and enzymes related to amino acid synthesis in the crop tissue of male and female pigeons during incubation and chick-rearing periods

The present study was carried out to investigate the changes in amino acid (AA) contents of crop milk and plasma and mRNA abundance of AA transporters and AA synthesis-related enzymes in the crop tissue of male and female pigeons during incubation and chick-rearing periods. Forty-two pairs of adult White King pigeons with 2 fertile eggs per pair were randomly divided into 7 groups by different breeding stages. The AA content of crop milk decreased from day 1 (R1) to day 25 (R25) of chick rearing (P < 0.05). In both male and female adult pigeons, the contents of Thr, Leu, Val, His, Asp, and Pro in plasma increased to maximum levels on R25. Parental sex effect and interaction between stage and sex were observed in the AA contents of pigeon plasma (P < 0.05). For AA transporters, the mRNA abundances of SNAT2, ASCT1, LAT1, and y+LAT2 in the male crops reached the highest value on day 17 of incubation (I17), and the peak mRNA levels of PAT-1, xCT, b0,+AT, and CAT1 were found on R7 (P < 0.05). In females, the abundances of ASCT1, B0AT1, asc-1, and CAT1 mRNA peaked on R1, whereas the maximum levels of LAT1, PAT-1, b0,+AT, and y+LAT2 were observed on R7. For enzymes involved in AA synthesis, the highest gene expressions of glutamate dehydrogenase 1, acetolactate synthase in both parent pigeons, and L-threonine 3-dehydrogenase in female pigeon crops were attained on I17. The expressions of ornithine-δ-aminotransferase, glutamic-oxal(o)acetic transaminase 1, glutamic-oxal(o)acetic transaminase 2, asparagine synthetase, serine hydroxymethyltransferase 2, and glutamic-pyruvic transaminase 2 in both sexes and argininosuccinate lyase and L-threonine 3-dehydrogenase in males were the highest on R1. In conclusion, AA used for pigeon crop milk formation may originate from plasma and intracellular synthesis. The genes involved in AA transport and synthesis varied significantly with sexual effects, indicating that other factors should be considered in future explorations of the mechanism of protein formation in crop milk.