Timing of Testicular Biopsy in Relation to Oocyte Retrieval and the Outcomes of Intracytoplasmic Sperm Injection

PURPOSE

We evaluate microscopic (micro) testicular sperm extraction (TESE) timing relative to oocyte retrieval on intracytoplasmic sperm injection outcome.

MATERIALS AND METHODS

Couples with nonobstructive azoospermia who underwent intracytoplasmic sperm injection with freshly retrieved spermatozoa were analyzed based on whether micro-TESE was performed at least 1 day prior to oocyte retrieval (TESE-day-before group) or on the day of oocyte retrieval (TESE-day-of group). Embryology and clinical outcomes were compared.

RESULTS

The percentage of patients who underwent a successful testicular sperm retrieval was significantly lower in the TESE-day-before cohort (62%) than in the TESE-day-of cohort (69%; odds ratio [OR] 1.4, 95% CI [1.1, 1.7], P < .001). The fertilization rate was also found to be significantly lower in the TESE-day-before group (45%) than in the TESE-day-of group (53%; OR 1.4, 95% CI [1.2, 1.7], P = .01). Although the association between the cleavage rate and TESE timing was not statistically significant, the implantation rate was found to be significantly higher in the day-before cohort (28%) than in the day-of cohort (22%; OR 0.7, 95% CI [0.6, 0.9], P = .01). Nevertheless, it was found that the clinical pregnancy and delivery rates were not statistically significantly associated with the TESE timing.

CONCLUSIONS

Although sperm retrieval and fertilization rates were lower in the TESE-day-before cohort, the 2 cohorts showed comparable embryologic and clinical outcomes. Micro-TESE can be performed before oocyte harvesting to provide physicians ample time to decide between cancelling oocyte retrieval or retrieving oocytes for cryopreservation.

Genetic profiling of azoospermic men to identify the etiology and predict reproductive potential

PURPOSE

To identify germline mutations related to azoospermia etiology and reproductive potential of surgically retrieved spermatozoa, and to investigate the feasibility of predicting seminiferous tubule function of nonobstructive azoospermic men by transcriptomic profiling of ejaculates.

MATERIALS AND METHODS

Sperm specimens were obtained from 30 men (38.4 ± 6 years) undergoing epididymal sperm aspiration for obstructive azoospermia (OA, n = 19) acquired by vasectomy, or testicular biopsy for nonobstructive azoospermia (NOA, n = 11). To evaluate for a correlation with azoospermia etiology, DNAseq was performed on surgically retrieved spermatozoa, and cell-free RNAseq on seminal fluid (n = 23) was performed to predict spermatogenesis in the seminiferous tubule.

RESULTS

Overall, surgically retrieved sperm aneuploidy rates were 1.7% and 1.8% among OA and NOA cohorts, respectively. OA men carried housekeeping-related gene mutations, while NOA men displayed mutations on genes involved in crucial spermiogenic functions (AP1S2, AP1G2, APOE). We categorized couples within each cohort according to ICSI clinical outcomes to investigate genetic causes that may affect reproductive potential. All OA-fertile men (n = 9) carried mutations in ZNF749 (sperm production), whereas OA-infertile men (n = 10) harbored mutations in PRB1, which is essential for DNA replication. NOA-fertile men (n = 8) carried mutations in MPIG6B (stem cell lineage differentiation), whereas NOA-infertile individuals (n = 3) harbored mutations in genes involved in spermato/spermio-genesis (ADAM29, SPATA31E1, MAK, POLG, IFT43, ATG9B) and early embryonic development (MBD5, CCAR1, PMEPA1, POLK, REC8, REPIN1, MAPRE3, ARL4C). Transcriptomic assessment of cell-free RNAs in seminal fluid from NOA men allowed the prediction of residual spermatogenic foci.

CONCLUSIONS

Sperm genome profiling provides invaluable information on azoospermia etiology and identifies gene-related mechanistic links to reproductive performance. Moreover, RNAseq assessment of seminal fluid from NOA men can help predict sperm retrieval during testicular biopsies.

Embryo ranking agreement between embryologists and artificial intelligence algorithms

OBJECTIVE

To evaluate the degree of agreement of embryo ranking between embryologists and eight artificial intelligence (AI) algorithms.

DESIGN

Retrospective study.

PATIENT(S)

A total of 100 cycles with at least eight embryos were selected from the Weill Cornell Medicine database. For each embryo, the full-length time-lapse (TL) videos, as well as a single embryo image at 120 hours, were given to five embryologists and eight AI algorithms for ranking.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Kendall rank correlation coefficient (Kendall's τ).

RESULT(S)

Embryologists had a high degree of agreement in the overall ranking of 100 cycles with an average Kendall's tau (K-τ) of 0.70, slightly lower than the interembryologist agreement when using a single image or video (average K-τ = 0.78). Overall agreement between embryologists and the AI algorithms was significantly lower (average K-τ = 0.53) and similar to the observed low inter-AI algorithm agreement (average K-τ = 0.47). Notably, two of the eight algorithms had a very low agreement with other ranking methodologies (average K-τ = 0.05) and between each other (K-τ = 0.01). The average agreement in selecting the best-quality embryo (1/8 in 100 cycles with an expected agreement by random chance of 12.5%; confidence interval [CI]95: 6%-19%) was 59.5% among embryologists and 40.3% for six AI algorithms. The incidence of the agreement for the two algorithms with the low overall agreement was 11.7%. Agreement on selecting the same top two embryos/cycle (expected agreement by random chance corresponds to 25.0%; CI95: 17%-32%) was 73.5% among embryologists and 56.0% among AI methods excluding two discordant algorithms, which had an average agreement of 24.4%, the expected range of agreement by random chance. Intraembryologist ranking agreement (single image vs. video) was 71.7% and 77.8% for single and top two embryos, respectively. Analysis of average raw scores indicated that cycles with low diversity of embryo quality generally resulted in a lower overall agreement between the methods (embryologists and AI models).

CONCLUSION(S)

To our knowledge, this is the first study that evaluates the level of agreement in ranking embryo quality between different AI algorithms and embryologists. The different concordance methods were consistent and indicated that the highest agreement was intraembryologist agreement, followed by interembryologist agreement. In contrast, the agreement between some of the AI algorithms and embryologists was similar to the inter-AI algorithm agreement, which also showed a wide range of pairwise concordance. Specifically, two AI models showed intra- and interagreement at the level expected from random selection.

Faster sperm selected by rheotaxis leads to superior early embryonic development in vitro

To understand the impact of sperm speed as they swim against the flow on fertilization rates, we created conditions similar to the female reproductive tract (FRT) on a microfluidic platform for sperm selection. Selected sperm were evaluated based on early development of fertilized embryos. Bovine and human spermatozoa were selected at various fluid flow rates within the device. We found that the speed of bovine spermatozoa increases as the flow rate increases and that the amount of DNA fragmentation index is lowered by increasing the flow rate. Bovine spermatozoa selected by our platform at low (150 μL h-1, shear rate 3 s-1), medium (250 μL h-1, shear rate 5 s-1), and high flow rates (350 μL h-1, shear rate 7 s-1) were used for fertilization and compared to sperm sorted by centrifugation. The samples collected at the highest flow rate resulted in the formation of 23% more blastocysts compared to the control. While selecting for higher quality sperm by increasing the flow rate does result in lower sperm yield, quality improvement and yield may be balanced by better embryonic development.

FIGO statement: Fertility preservation

Fertility preservation is a growing field in reproductive medicine that may raise ethical questions. Preservation of fertility must be discussed with the patient if gonadotoxic treatment is required, whether in the case of benign or malignant pathology, or in the management of transgender identity. As a result, surgery or chemotherapy that has fewer adverse impacts on fertility should be proposed if this does not alter the prognosis of the disease. If the risk of infertility persists, then fertility cryopreservation should be proposed for children and adults of reproductive age. Sperm, oocytes, and gonadal tissue can be cryopreserved for many years. FIGO wishes to emphasize the importance of fertility preservation in the medical and surgical management of patients, and the importance of a specialized, multidisciplinary approach.

Successful cryptozoospermia management with multiple semen specimen collection

OBJECTIVE

To determine the prevalence of sperm suitable for intracytoplasmic sperm injection (ICSI) in fresh ejaculated semen samples provided by men scheduled for a microdissection testicular sperm extraction (mTESE) procedure. Secondary objectives included an evaluation of the effect of a short abstinence period on semen quality and ICSI outcomes for men with cryptozoospermia.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center.

PATIENTS

All men were scheduled to undergo a mTESE procedure by a single, high-volume surgeon at an academic center from September 1, 2015, to May 1, 2021.

INTERVENTION

Presence of sperm suitable for ICSI in the ejaculate on the day of scheduled mTESE.

MAIN OUTCOME MEASURES

Prevalence of sperm suitable for ICSI in the ejaculate among previously diagnosed men with azoospermia. Secondary outcomes included changes in semen parameters, clinical pregnancy rate, and live birth rate.

RESULTS

Of 727 planned mTESE procedures, 69 (9.5%) were canceled because sperm suitable for ICSI were identified in a fresh ejaculated sample produced on the day of scheduled surgery (typically one day before oocyte retrieval). Overall, 50 men (50/727, 6.9%) used these rare, ejaculated sperm for ICSI. Semen samples obtained with <24 hours of abstinence were more likely to have better motility than the sample initially provided on the day of the planned mTESE. The live birth rate per ICSI attempt using these rare, ejaculated sperm was 36% (19/53).

CONCLUSION

Providing a fresh ejaculated semen sample on the day of mTESE allows nearly 10% of men with azoospermia to avoid surgery with satisfactory ICSI outcomes. Providing multiple ejaculated samples over a short period of time does not adversely affect sperm concentration and may enhance sperm motility in men with cryptozoospermia.

Can a sperm selection technique improve embryo ploidy?

BACKGROUND

Spermatozoa with the highest motility retain a superior genomic integrity, and elevated sperm chromatin fragmentation (SCF) has been linked to a lower ability of the conceptus to develop and implant. Therefore, the utilization of a sperm selection method, such as microfluidic sperm selection (MFSS), is capable of reducing the SCF by yielding the most motile fraction of spermatozoa with the highest embryo developmental competence. What remains unclear, however, is the causal mechanism that links SCF to an impaired embryo development.

OBJECTIVES

To identify a relationship between SCF and an unexpectedly high proportion of embryo aneuploidy, while addressing treatment options.

MATERIALS AND METHODS

We identified couples with a high incidence of embryo aneuploidy in a previous intracytoplasmic sperm injection (ICSI) cycle with pre-implantation genetic testing for aneuploidy (PGT-A), utilizing spermatozoa selected by density gradient (DG). Terminal deoxynucleotidyl dUTP transferase nick-end labeling (TUNEL) and neutral Comet assays were carried out on the semen specimens to assess total SCF and double-stranded DNA (dsDNA) fragmentation, respectively. These couples underwent subsequent ICSI/PGT-A cycles with MFSS. Total SCF and dsDNA fragmentation were compared between the two sperm selection methods. Embryo aneuploidy, implantation, clinical pregnancy, delivery, and pregnancy loss rates were compared between the couples' historical DG and subsequent MFSS cycles.

RESULTS

In 57 couples undergoing 71 ICSI/PGT-A cycles, where DG sperm selection was carried out, a high incidence of aneuploid embryos (74.7%) resulted in poor implantation and no viable pregnancies. Testing for SCF, inclusive of dsDNA breaks, evidenced a SCF of 26.2% and dsDNA break of 3.6% in the raw specimen, that decreased to 18.0% (p < 0.001) and 3.1%, respectively, in the DG processed specimen. Following MFSS, total SCF and dsDNA fragmentation decreased to 1.9% and 0.3%, respectively (p < 0.001). The embryo euploidy rate remarkable improved from 25.3% in the DG cycles to 42.9% in the MFSS cycles (p < 0.001). The 6.7% implantation rate in the DG cycles increased to 65.5% in the MFSS cycles (p < 0.001). Similarly, the clinical pregnancy rate rose from 10.5% (DG) to 64.6% (MFSS), resulting in a 62.5% delivery rate (p < 0.001).

DISCUSSION AND CONCLUSIONS

In couples with a relatively young female partner with a negative infertility workup, and a male partner with semen parameters adequate for ICSI, presenting with a high rate of embryo aneuploidy, an additional subtle male factor component may be the culprit. Thus, it is crucial to assess the SCF and test for the dsDNA breaks, which can eventually contribute to embryo chromosomal abnormalities. Given the inverse relationship between SCF and motility, a selection of the most motile gamete by MFSS enhanced the proportion of spermatozoa with an intact genome, contributing to the generation of more euploid embryos that are capable of implanting and yielding increased term pregnancies.

Sperm centriolar factors and genetic defects that can predict pregnancy

The human sperm centrosome, comprising the two morphologically distinct centrioles and associated pericentriolar materials, plays a crucial role in fertilization and early embryonic development after fertilization. Once inside the oocyte, the sperm centrosome serves as a microtubule-organizing center, orchestrating mitotic spindle formation, chromosome segregation, and syngamy. Abnormalities of the sperm centrosome can lead to abnormal embryonic development and embryonic chromosomal instability, and are associated with pregnancy loss. Recent research has shed light on the molecular composition, regulation, and function of this vital organelle. Understanding the intricacies of the sperm centrosome is crucial for elucidating the mechanisms underlying successful fertilization and early embryonic development, as well as addressing infertility and developmental disorders associated with centrosomal defects.

Automatic Ploidy Prediction and Quality Assessment of Human Blastocyst Using Time-Lapse Imaging

Assessing fertilized human embryos is crucial for in vitro-fertilization (IVF), a task being revolutionized by artificial intelligence and deep learning. Existing models used for embryo quality assessment and chromosomal abnormality (ploidy) detection could be significantly improved by effectively utilizing time-lapse imaging to identify critical developmental time points for maximizing prediction accuracy. Addressing this, we developed and compared various embryo ploidy status prediction models across distinct embryo development stages. We present BELA (Blastocyst Evaluation Learning Algorithm), a state-of-the-art ploidy prediction model surpassing previous image- and video-based models, without necessitating subjective input from embryologists. BELA uses multitask learning to predict quality scores that are used downstream to predict ploidy status. By achieving an AUC of 0.76 for discriminating between euploidy and aneuploidy embryos on the Weill Cornell dataset, BELA matches the performance of models trained on embryologists' manual scores. While not a replacement for preimplantation genetic testing for aneuploidy (PGT-A), BELA exemplifies how such models can streamline the embryo evaluation process, reducing time and effort required by embryologists.

A novel approach toward the generation of oocytes by direct diploid cell haploidization

Oocyte-mediated somatic cell haploidization is a process in which a diploid cell halves its chromosomal content by segregating its homologue within the ooplasm. Replacing the donor oocyte nucleus with a patient's female diploid somatic nucleus can generate patient-genotyped oocytes. Insemination of these resulting constructs enables their activation and induces a reductive meiotic division, haploidizing the diploid female donor cell that can subsequently support syngamy with the male genome and create a zygote. So far, experimental data for this method have been limited and have not consistently proven the generation of chromosomally normal embryos. Overall, we achieved reconstruction of murine oocytes with a micromanipulation survival rate of 56.5%, and a correct haploidization and fertilization rate of 31.2%, resulting in a 12.7% blastocyst rate. Time-lapse analysis revealed that reconstructed embryos underwent a timely polar body extrusion and pronuclear appearance followed by a satisfactory embryonic cleavage, comparable with the control. Whole genome sequencing of the analyzed embryos indicated that 27.3% (6/22) were properly diploid. Our findings suggest that diploid cell haploidization may be a feasible technique for creating functional gametes in mammals.

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

Objective

To treat couples with total fertilization failure (TFF) based on a combined oocyte- and sperm-related oocyte activation deficiency by optimizing oocyte response to chemical activation with calcium ionophore.

Design

Case report.

Setting

Tertiary Hospital.

Patients

Two couples with a history of TFF after intracytoplasmic sperm injection intracytoplasmic sperm injection (ICSI).

Interventions

To overcome oocyte-related oocyte activation deficiency (OAD), extended in vivo/in vitro oocyte maturation was performed to enhance ooplasmic maturity; to address sperm-related OAD, assisted gamete treatment (AGT) was performed to trigger oocyte activation.

Main outcome measures

Treatment cycle outcomes for the 2 couples undergoing ICSI with extended oocyte maturation (EOM) and AGT.

Results

We identified 2 couples with TFF after ICSI because of a combined factor of OAD confirmed by phospholipase C zeta expression and genomic assessment. Initial AGT treatment alone failed to enhance fertilization, suggesting superimposed oocyte dysmaturity prohibiting oocytes from responding to chemical stimuli. To address this complex form of OAD, in couple 1, 27 oocytes out of 34 retrieved presented normal metaphase II spindles after EOM; ICSI with AGT yielded a fertilization rate of 63.0% (17/27). All 17 zygotes were cryopreserved initially. Two embryos were thawed and transferred, yielding a monochorionic diamniotic twin pregnancy. Couple 2 underwent 3 ICSI cycles with EOM and AGT; 91.4% (32/35) of oocytes displayed normal metaphase II spindle and achieved an overall fertilization rate of 43.8% (14/32). A total of 12 blastocysts were cryopreserved. A single 46XY blastocyst was thawed and transferred, resulting in a singleton pregnancy.

Conclusions

Our study has demonstrated the usefulness of EOM by targeting spindle presence to enhance chemical responses to AGT.

Assessing male gamete genome integrity to ameliorate poor assisted reproductive technology clinical outcome

OBJECTIVE

To assess the role of evaluating sperm chromatin fragmentation (SCF) as a tool to guide treatment in couples who achieved unexpectedly poor clinical outcomes after intracytoplasmic sperm injection (ICSI).

DESIGN

We identified couples with an unexpectedly suboptimal clinical outcome after ICSI who were then screened for SCF. Consequently, the same couples were counseled to undergo a subsequent ICSI cycle using either ejaculates processed by microfluidic sperm selection (MFSS) or spermatozoa retrieved from the testis, and clinical outcomes were compared between history and treatment cycles. To confirm the sole effect of a compromised male gamete, we compared the ICSI outcome in cycles where male gametes with abnormal SCF were used to inseminate autologous and donor oocytes. Finally, to eliminate an eventual confounding female factor component, we compared the clinical outcome of ICSI cycles using sibling donor oocytes injected with spermatozoa with normal or abnormal SCF.

SETTING

Academic reproductive medicine center point of care.

PATIENT(S)

The patient population consisted of 76 couples with reproductively healthy and relatively young female partners and male partners with compromised semen parameters, but suitable for ICSI. In a subanalysis, we identified 67 couples with abnormal SCF who underwent ICSI cycle(s) with donor oocytes. Furthermore, we identified 29 couples, 12 with normal SCF and 17 with abnormal, uncorrected SCF, and 7 couples with abnormal, corrected SCF vs. a control, who used sibling donor oocytes for their ICSI cycle(s).

INTERVENTION(S)

For couples who resulted in surprisingly low clinical outcomes after ICSI, despite semen parameters adequate for ICSI and a normal female infertility evaluation, a SCF assessment was performed on the semen specimen using the terminal deoxynucleotidyl transferase-mediated fluorescein-deoxyuridine triphosphate nick-end labeling (TUNEL) assay. The couples then underwent a subsequent ICSI cycle with spermatozoa processed by MFSS or surgically retrieved. Moreover, cycles with donor oocytes were used to confirm the sole contribution of the male gamete.

MAIN OUTCOME MEASURE(S)

Clinical outcomes, such as fertilization, embryo implantation, clinical pregnancy, delivery, and pregnancy loss rates were compared between history and treatment cycle(s) using ejaculated spermatozoa selected by MFSS or from a testicular biopsy, taking into consideration the level of SCF. In a subanalysis, we reported the clinical outcomes of 67 patients who used donor oocytes and compared them with cycles where their own oocytes were used. Furthermore, we compared the ICSI clinical outcomes between cycles using sibling donor oocytes injected with low or high SCF with or without sperm intervention aimed at correcting, or alleviating the degree of SCF.

RESULT(S)

In a total of 168 cycles, 76 couples had in a prior cycle a 67.1% fertilization rate, and clinical pregnancy and pregnancy loss rates of 16.6% and 52.3%, respectively. After testing for SCF, the DNA fragmentation rate was 21.6%. This led to a subsequent ICSI cycle with MFSS or testicular sperm extraction, resulting in clinical pregnancy and delivery rates of 39.2%, and 37.3%, respectively. The embryo implantation rate increased to 23.5%, whereas the pregnancy loss rate decreased to 5% in the treatment cycle. This was particularly significant in the moderate SCF group, reaching embryo implantation, clinical pregnancy, and delivery rates of 24.3%, 40.4%, and 36.2%, respectively, and reducing the pregnancy loss rate to 10.5% in post-sperm treatment cycles. In 67 patients with high SCF who used donor oocytes, a significantly higher fertilization rate of 78.1% and embryo implantation rate of 29.1% were reported, compared with those in couples also with an elevated SCF who used their own. Interestingly, the clinical pregnancy and delivery rates only increased slightly from 28.0%-36.1% and from 23.7%-29.2%, respectively. To further control for a female factor, we observed couples who shared sibling donor oocytes, 17 with normal SCF and 12 with abnormal (uncorrected) SCF. Interestingly, the abnormal SCF group had impaired fertilization (69.3%), embryo implantation (15.0%), and delivery (15.4%) rates. For an additional 15 couples who split their donor oocytes, 8 had normal SCF, and although 7 couples originally had abnormal SCF, 4 used microfluidic processing, 2 used testicular spermatozoa, and 1 used donor spermatozoa to alleviate the degree of SCF, resulting in comparable clinical outcomes with the normal SCF group.

CONCLUSION(S)

A superimposed male factor component may explain the disappointing ICSI outcome in some couples despite reproductively healthy female partners. Therefore, it may be useful to screen couples for SCF to guide treatment options and maximize chances of a successful pregnancy. The improved, but suboptimal pregnancy and delivery outcomes observed in couples using donor oocytes confirmed the exclusive detrimental role that the male gamete exerted on embryo development despite the presence of putative oocyte repair mechanisms.

Profiling the male germline genome to unravel its reproductive potential

OBJECTIVE

To identify specific germline mutations related to sperm reproductive competence, in couples with unexplained infertility.

DESIGN

In this retrospective study, couples were divided according to whether they had successful intracytoplasmic sperm injection outcomes (fertile) or not (infertile). Ancillary sperm function tests were performed on ejaculates, and whole exome sequencing was performed on spermatozoal DNA. Sperm aneuploidy and gene mutation profiles were compared between the 2 cohorts as well as according to the specific reasons for reproductive failure.

SETTING

Center for reproductive medicine at a major academic medical center.

PATIENT(S)

Thirty-one couples with negative infertility workups and normal semen parameters.

INTERVENTION(S)

Couples with mutations on fertilization- or embryo development-related genes were subsequently treated by assisted gamete treatment or microfluidics, respectively.

MAIN OUTCOME MEASURE(S)

Intracytoplasmic sperm injection cycle outcomes including fertilization, clinical pregnancy, and delivery rates.

RESULT(S)

Sperm aneuploidy was lower in the fertile group (4.0% vs. 8.4%). Spermatozoa from both cohorts displayed mutations associated with sperm-egg fusion (ADAM3A) and acrosomal development (SPACA1), regardless of reproductive outcome. The infertile cohort was then categorized according to the reasons for reproductive failure: absent fertilization, poor early embryo development, implantation failure, or pregnancy loss. Spermatozoa from the fertilization failure subgroup (n = 4) had negligible PLCζ presence (10% ± 9%) and gene mutations (PLCZ1, PIWIL1, ADAM15) indicating a sperm-related oocyte-activating deficiency. These couples were successfully treated by assisted gamete treatment in their subsequent cycles. Spermatozoa from the poor early embryo development subgroup (n = 5) had abnormal centrosomes (45.9% ± 5%), and displayed mutations impacting centrosome integrity (HAUS1) and spindle/microtubular stabilization (KIF4A, XRN1). Microfluidic sperm processing subsequently yielded a term pregnancy. Spermatozoa from the implantation failure subgroup (n = 7) also had abnormal centrosomes (53.1% ± 13%) and carried mutations affecting embryonic implantation (IL9R) and microtubule and centrosomal integrity (MAP1S, SUPT5H, PLK4), whereas those from the pregnancy loss subgroup (n = 5) displayed mutations on genes involved in trophoblast development (NLRP7), cell cycle regulation (MARK4, TRIP13, DAB2IP, KIF1C), and recurrent miscarriage (TP53).

CONCLUSION(S)

By assessing the sperm genome, we identified specific germline mutations related to various reproductive processes. This information may clarify elusive factors underlying reproductive competence and enhance treatment for couples with unexplained infertility.

Human theca arises from ovarian stroma and is comprised of three discrete subtypes

Theca cells serve multiple essential functions during the growth and maturation of ovarian follicles, providing structural, metabolic, and steroidogenic support. While the function of theca during folliculogenesis is well established, their cellular origins and the differentiation hierarchy that generates distinct theca sub-types, remain unknown. Here, we performed single cell multi-omics analysis of primary cell populations purified from human antral stage follicles (1-3 mm) to define the differentiation trajectory of theca/stroma cells. We then corroborated the temporal emergence and growth kinetics of defined theca/stroma subpopulations using human ovarian tissue samples and xenografts of cryopreserved/thawed ovarian cortex, respectively. We identified three lineage specific derivatives termed structural, androgenic, and perifollicular theca cells, as well as their putative lineage-negative progenitor. These findings provide a framework for understanding the differentiation process that occurs in each primordial follicle and identifies specific cellular/molecular phenotypes that may be relevant to either diagnosis or treatment of ovarian pathologies.

A non-randomized clinical trial to determine the safety and efficacy of a novel sperm sex selection technique

The desire to have offspring of a specific sex has a long history but has been particularly present with the appearance of assisted reproduction. However, embryo selection raises ethical concerns. Thus, several techniques to select sex-specific spermatozoa have been proposed but carry limitations. There are many variations of each technique, and some are time consuming and costly. Concerns about effectiveness and safety have also rendered many of them unappealing. Therefore, we propose a novel sperm sex selection technique (SST) that appears to be consistently safe and effective. A single-center, non-randomized clinical trial was designed. We included 1,317 couples, who were assigned to one of two groups: ICSI/PGTA or ICSI/PGTA+GS. Ejaculates from male partners of couples in the ICSI/PGTA+GS group (n = 105) were processed using SST to enrich spermatozoa for their desired sex. Standard sperm processing was carried out for couples undergoing PGT-A solely for aneuploidy (n = 1,212), comprising the ICSI/PGTA control group. To validate the efficacy of our technique, we performed an analysis on spermatozoa pre- and post-selection, followed by an assessment of the proportion of the conceptuses' sex to confirm clinical reliability. We also followed up on ICSI clinical outcomes and child/newborn health to establish the safety of our method. Our main outcome measures included the proportion of spermatozoa and embryos enriched for female and male sex, as well as embryo euploidy rates and ICSI clinical outcomes. These outcomes were compared between the two groups. For the ICSI/PGTA group (n = 1,212) (maternal age, 37.0±4yrs; paternal age, 39.1±6yrs), with ejaculated spermatozoa processed in the standard fashion, 2,303 ICSI cycles (1.2±1) yielded an 81.0% (14,375/17,737) fertilization. PGT-A results indicated a euploidy rate of 73.1% (n = 3,718) for female and 72.4% (n = 3,054) for male embryos. These couples achieved a 76.4% (699/915) implantation and 65.2% (597/915) clinical pregnancy rate, with 551 deliveries (48.5% female, 51.5% male). All 105 men in the ICSI/PGTA+GS group had sperm specimens with an equal sex distribution at baseline. Of them, 59 (paternal age, 40.9±6yrs) who desired female offspring obtained an 81.6% enrichment after SST. They underwent 73 ICSI cycles with their partners (maternal age, 37.9±4yrs), achieving a 77.3% (583/754) fertilization. This resulted in 79.1% (231/292) female embryos that generated a 79.3% (23/29) implantation rate, with 16 singleton deliveries of the desired female sex without major or minor congenital malformations. Forty-six couples (maternal age, 37.3±4yrs; paternal age, 40.7±6yrs) desiring male offspring obtained an 80.8% sperm sex enrichment. They underwent 50 ICSI cycles, achieving a 75.4% (462/613) fertilization and equivalent proportion of male embryos (223/280, 79.6%). Their implantation was 90.5% (19/21), with 13 singleton deliveries of healthy male offspring. Furthermore, 78.8% (182/231) of female and 66.4% (148/223) of male embryos from the ICSI/PGTA+GS cohort were euploid. These euploid rates were comparable to those from the ICSI/PGTA group. In couples undergoing ICSI with PGT-A, SST consistently enriched spermatozoa, resulting in a higher proportion of embryos and thus offspring of the desired sex. Moreover, SST did not impair the fertilization or embryo developmental competence of spermatozoa, nor did it affect offspring health. Trial registration: Clinicaltrials.gov NCT05500573.

A non-invasive artificial intelligence approach for the prediction of human blastocyst ploidy: a retrospective model development and validation study

BACKGROUND

One challenge in the field of in-vitro fertilisation is the selection of the most viable embryos for transfer. Morphological quality assessment and morphokinetic analysis both have the disadvantage of intra-observer and inter-observer variability. A third method, preimplantation genetic testing for aneuploidy (PGT-A), has limitations too, including its invasiveness and cost. We hypothesised that differences in aneuploid and euploid embryos that allow for model-based classification are reflected in morphology, morphokinetics, and associated clinical information.

METHODS

In this retrospective study, we used machine-learning and deep-learning approaches to develop STORK-A, a non-invasive and automated method of embryo evaluation that uses artificial intelligence to predict embryo ploidy status. Our method used a dataset of 10 378 embryos that consisted of static images captured at 110 h after intracytoplasmic sperm injection, morphokinetic parameters, blastocyst morphological assessments, maternal age, and ploidy status. Independent and external datasets, Weill Cornell Medicine EmbryoScope+ (WCM-ES+; Weill Cornell Medicine Center of Reproductive Medicine, NY, USA) and IVI Valencia (IVI Valencia, Health Research Institute la Fe, Valencia, Spain) were used to test the generalisability of STORK-A and were compared measuring accuracy and area under the receiver operating characteristic curve (AUC).

FINDINGS

Analysis and model development included the use of 10 378 embryos, all with PGT-A results, from 1385 patients (maternal age range 21-48 years; mean age 36·98 years [SD 4·62]). STORK-A predicted aneuploid versus euploid embryos with an accuracy of 69·3% (95% CI 66·9-71·5; AUC 0·761; positive predictive value [PPV] 76·1%; negative predictive value [NPV] 62·1%) when using images, maternal age, morphokinetics, and blastocyst score. A second classification task trained to predict complex aneuploidy versus euploidy and single aneuploidy produced an accuracy of 74·0% (95% CI 71·7-76·1; AUC 0·760; PPV 54·9%; NPV 87·6%) using an image, maternal age, morphokinetic parameters, and blastocyst grade. A third classification task trained to predict complex aneuploidy versus euploidy had an accuracy of 77·6% (95% CI 75·0-80·0; AUC 0·847; PPV 76·7%; NPV 78·0%). STORK-A reported accuracies of 63·4% (AUC 0·702) on the WCM-ES+ dataset and 65·7% (AUC 0·715) on the IVI Valencia dataset, when using an image, maternal age, and morphokinetic parameters, similar to the STORK-A test dataset accuracy of 67·8% (AUC 0·737), showing generalisability.

INTERPRETATION

As a proof of concept, STORK-A shows an ability to predict embryo ploidy in a non-invasive manner and shows future potential as a standardised supplementation to traditional methods of embryo selection and prioritisation for implantation or recommendation for PGT-A.

FUNDING

US National Institutes of Health.

Extraction, Labeling, and Purification of Lineage-Specific Cells from Human Antral Follicles

The activation, growth, development, and maturation of oocytes is a complex process that is coordinated not just between multiple cell types of the ovary but also across multiple points of control within the hypothalamic/pituitary/ovarian circuit. Within the ovary, multiple specialized cell types grow in close association with the oocyte within the ovarian follicles. The biology of these cells has been well described at the later stages, when they are easily recovered as byproducts of assisted reproductive treatments. However, the in-depth analysis of small antral follicles isolated directly from the ovary is not commonly carried out due to the scarcity of human ovarian tissue and the limited access to the ovary in patients undergoing assisted reproductive treatments. These methods for processing whole ovaries for the cryopreservation of cortical strips with the concurrent identification/isolation of ovary resident cells enable the high-resolution analysis of the early stages of antral follicle development. We demonstrate protocols for isolating discrete cell types by treating antral follicles enzymatically and separating the granulosa, theca, endothelial, hematopoietic, and stromal cells. The isolation of cells from the antral follicles at various sizes and developmental stages enables the comprehensive analysis of the cellular and molecular mechanisms that drive follicle growth and ovarian physiology and provides a source of viable cells that can be cultured in vitro to recapitulate the follicle microenvironment.

Error-prone repair of stalled replication forks drives mutagenesis and loss of heterozygosity in haploinsufficient BRCA1 cells

Germline mutations in the BRCA genes are associated with a higher risk of carcinogenesis, which is linked to an increased mutation rate and loss of the second unaffected BRCA allele (loss of heterozygosity, LOH). However, the mechanisms triggering mutagenesis are not clearly understood. The BRCA genes contain high numbers of repetitive DNA sequences. We detected replication forks stalling, DNA breaks, and deletions at these sites in haploinsufficient BRCA cells, thus identifying the BRCA genes as fragile sites. Next, we found that stalled forks are repaired by error-prone pathways, such as microhomology-mediated break-induced replication (MMBIR) in haploinsufficient BRCA1 breast epithelial cells. We detected MMBIR mutations in BRCA1 tumor cells and noticed deletions-insertions (>50 bp) at the BRCA1 genes in BRCA1 patients. Altogether, these results suggest that under stress, error-prone repair of stalled forks is upregulated and induces mutations, including complex genomic rearrangements at the BRCA genes (LOH), in haploinsufficient BRCA1 cells.

Xenograft model of heterotopic transplantation of human ovarian cortical tissue and its clinical relevance

In brief

Xenografts of human ovarian cortical tissue provide a tractable model of heterotopic autotransplantation that is used for fertility preservation in patients undergoing ablative chemo/radiotherapy. This study describes the behavior of hundreds of xenografts to establish a framework for the clinical function of ovarian cortex following autotransplantation over short- and long-term intervals.

Abstract

More than 200 live births have been achieved using autotransplantation of cryopreserved ovarian cortical fragments, yet challenges remain to be addressed. Ischemia of grafted tissue undermines viability and longevity, typically requiring transplantation of multiple cortical pieces; and the dynamics of recruitment within a graft and the influence of parameters like size and patient age at the time of cryopreservation are not well-defined. Here, we describe results from a series of experiments in which we xenografted frozen/thawed human ovarian tissue (n = 440) from 28 girls and women (age range 32 weeks gestational age to 46 years, median 24.3 ± 4.6). Xenografts were recovered across a broad range of intervals (1-52 weeks post-transplantation) and examined histologically to quantify follicle density and distribution. The number of antral follicles in xenografted cortical fragments correlated positively with the total follicle number and was significantly reduced with increased patient age. Within xenografts, follicles were distributed in focal clusters, similar to the native ovary, but the presence of a leading antral follicle coincided with increased proliferation of surrounding follicles. These results underscore the importance of transplanting ovarian tissue with a high density of follicles and elucidate a potential paracrine influence of leading antral follicles on neighboring follicles of earlier stages. This temporal framework for interpreting the kinetics of follicle growth/mobilization may be useful in setting expectations and guiding the parameters of clinical autotransplantation.

The use of fertility preservation services for cancer patients: a single institution experience

Objective

To analyze the use of services regarding fertility preservation (FP) in cancer patients at a single institution.

Design

A retrospective cohort study.

Setting

Academic medical center.

Patients

A total of 208 FP referrals.

Interventions

None.

Main Outcome Measures

Method of FP; time from referral to FP intervention.

Results

A total of 553 patients were referred to a reproductive specialist for FP in the setting of a medical diagnosis from 2011 to 2016. Of these, 208 patients satisfied the inclusion criteria and met with a reproductive specialist. Ninety patients underwent FP services. The average age at referral was 30.9 ± 7.9 years. Breast cancer (n=94, 45%) and leukemia/lymphoma (n=62, 30%) were the most prevalent cancer diagnoses. A 68.9% of patients underwent oocyte cryopreservation (n=62), 26.7% underwent embryo cryopreservation (n=24) and 4.4% underwent ovarian tissue preservation (n=4). The time interval from the referral to the FP intervention ranged from 1 to 810 days, with a median of 17 days.

Conclusions

In the setting of a cancer diagnosis, most patients undergoing FP intervention underwent oocyte cryopreservation, were <35 years old, and underwent FP intervention in <30 days from referral. Whereas FP should ideally be initiated at the time of cancer diagnosis, all patients with a cancer diagnosis should be referred to a reproductive specialist and counseled on options for FP to preserve the optionality for the reproductive future they desire.

P-798 Utilization of Haploid Androgenetic Blastomeres to Characterize Male Genomic Inheritance and as a Male Gamete Substitute

Study question

Can sperm genomes be replicated by generating androgenetic embryos, and can resulting haploid blastomeres be used as a substitute for male gametes with known genotype?

Summary answer

Once utilized as male gametes, haploid androgenetic blastomeres can be used for gamete genotyping and can sustain embryo development to live offspring.

What is known already

Heterozygosity in human spermatozoa may represent a risk to offspring health. This has led to attempts to replicate the gamete genome by generating haploid embryonic stem cells (haESCs) that can be used to typify heterozygosity or as gamete substitutes. Although haESC lines are unstable with a tendency to self-diploidize, utilizing haploid androgenetic cells in the early embryonic stages, such as the blastomere stage, can provide multiple copies of genetically functional pseudo-gametes.

Study design, size, duration

Haploid androgenetic embryos were generated using spermatozoa from B6 heterozygous mice (B6-EGFP x B6D2F1) and cultured until the 8-cell stage. Individual haploid blastomeres with green fluorescent protein (GFP) expression were fused with activated recipient oocytes. Resulting conceptuses were cultured in a time-lapse system to monitor each stage of preimplantation development. Blastocysts with GFP expression were transferred to pseudo-pregnant surrogates. Pregnancy and offspring reproductive health were evaluated. Piezo-actuated ICSI was performed on unmanipulated oocytes as control.

Participants/materials, setting, methods

To generate haploid androgenetic embryos, metaphase II oocytes of B6D2F1 mice were treated with cytochalasin B, enucleated under Oosight®, and inseminated by piezo-actuated ICSI. Haploid androgenetic embryos were cultured to the 8-cell stage. Androgenetic blastomeres with GFP expression were coated with inactivated Sendai-virus and grafted to an activated recipient oocyte from another cohort. Cleavage parameters of reconstructed zygotes were compared to controls. Blastocysts were transferred into the uterine cavity of a 2.5-day post-coitus CD-1 surrogate.

Main results and the role of chance

A total of 421 oocytes were enucleated with a survival rate of 98.6%. The ooplasts underwent ICSI; 351 (84.6%) constructs developed a single male pronucleus 4-6h post-ICSI, and 208 (59.3%) constructs cleaved to the 8-cell stage. Parthenogenic activation by calcium ionophore was successful in 96.4% of the recipient oocytes, confirmed by the appearance of a single female pronucleus. A total of 148 haploid androgenotes with GFP expression were grafted onto corresponding activated oocytes; 145 successfully fused. Up to 2 unused sibling haploid blastomeres per embryo were genotyped using whole exome sequencing by a reference laboratory. A total of 481 untreated oocytes were inseminated, yielding 437 control zygotes. The cleavage of reconstructed embryos into the 2-cell (96.4%), 4-cell (94.3%), and 8-cell stage (91.4%) was comparable to that of control conceptuses (97.5%, 93.8%, and 92.7% respectively). Although morula compaction (80.0%) and blastulation (60.7%) were lower than control (89.2% and 80.8%, P &lt;0.001, respectively), morphokinetic parameters were comparable. A total of 45 blastocysts were transferred into 5 recipient mice; 8 blastocysts implanted (17.8%) in 2 surrogates, yielding 5 live offspring (11.1%) weighing 1.51±0.22g. All live offspring expressed GFP and were confirmed fertile once reaching adulthood.

Limitations, reasons for caution

Although copies of gamete substitutes were generated that could be genotyped and used to produce live offspring with the desired phenotype in a mouse model, the system needs to be optimized and proven reproducible in humans, specifically in regard to the role of the sperm centrosome.

Wider implications of the findings

Once our proposed technique is implemented in humans, it may benefit patients to control germline heterozygosity by allowing genotyping of identical copies of the gametes. This technique, when used in conjunction with heritable genomic editing, can obviate the inherently highly condensed sperm genome to provide genome-edited gamete substitutes.

Trial registration number

N/A

O-310 Browsing the Male Genome to Unravel Its Reproductive Potential

Study question

Can whole genome profiling of sperm DNA be used to identify aspects of ART failure and predict embryo developmental competence?

Summary answer

Whole genome profiling of sperm DNA identifies germline gene mutations associated with reproductive failure and helps characterize subtle male factor infertility.

What is known already

A routine semen analysis provides limited information on the characteristics of the male gamete and is unable to predict spermatozoa performance in ART. Therefore, ancillary tests may be used to further assess the male gamete’s reproductive potential. Whole exome sequencing (WES) of the male genome carried out on somatic cells has proven to be a powerful technique capable of identifying the genetic roots of infertility. Here, we aim to preferentially detect germline mutations by exclusively sequencing spermatozoal DNA to identify genes related to the different underlying etiologies of reproductive failure.

Study design, size, duration

Over a 6-year period, 31 consenting couples with negative female infertility workups and normal semen parameters were included in this study. These couples were divided according to whether they reported a successful pregnancy with ART (fertile; n = 10) or not (infertile; n = 21). Sperm aneuploidy assessment by copy number variant (CNV) analysis with WES were carried out on ejaculated spermatozoa. Gene mutation profiles were enlisted and compared between the two patient cohorts to identify genes involved.

Participants/materials, setting, methods

DNA was extracted and amplified from at least 500 spermatozoa (DNA concentration, 760±486 ng/ul; quality, 1.7±0.1 nm) for CNV analyses by WES. Mutations corresponding to the CNV were then annotated and assessed using the CLC Genomic Server 9.0. Genes were considered duplicated or deleted when their read depth was &gt;1.5 or &lt; 0.5 times the median read depth in the control, respectively.

Main results and the role of chance

All couples (n = 31) (maternal age, 37.6±3yrs; paternal age, 39.7±5yrs) had adequate semen parameters (concentration, 59.2±30x106/mL, 44.8±18% motility, normal morphology) and normal peripheral karyotypes.

The fertile cohort (n = 10) underwent 12 ICSI cycles, achieving an 82.6% (57/69) fertilization rate with 10/12 (83.3%) cycles resulting in live births. The infertile cohort (n = 21) underwent 25 ICSI cycles, achieving a 68.4% (91/133) fertilization rate and 6/14 (42.9%) clinical pregnancies, all resulting in pregnancy loss. CNV analysis indicated lower sperm aneuploidy in the fertile (4.0% vs. 8.4%) cohort (P &lt; 0.00001). In both cohorts, mutations associated with sperm–egg fusion (ADAM3A) and acrosomal development (SPACA1, SPATA16) were identified, justifying ICSI utilization.

The infertile cohort included complete fertilization failure, poor early embryo development, implantation failure, or pregnancy loss. Couples with complete fertilization failure (n = 4) had gene deletions (PLCZ1, PIWIL1, ADAM15) indicating sperm-related oocyte-activating deficiency. Those with poor early embryo development (n = 5) had mutations essential for centrosome integrity (HAUS1) and spindle/microtubular stabilization (KIF4A, XRN1). Couples who failed to achieve pregnancy (n = 7) had mutations commonly implicated in embryonic implantation (IL9R) and microtubule/centrosomal integrity (MAP1S). Those with pregnancy losses (n = 5) displayed mutations related to trophoblast development (NLRP7), cell cycle regulation (MARK4, TRIP13, DAB2IP, KIF1C), and a gene linked to recurrent miscarriage (TP53).

Limitations, reasons for caution

Using WES, we were able to identify germline mutations that appear to be involved in various aspects of human reproduction. These findings are new and should be validated in a larger study population. Moreover, although we attempted to control for maternal age, we still cannot exclude confounding female factors.

Wider implications of the findings

Evaluating the sperm genome can help identify elusive genetic factors associated with reproductive competence and help guide treatment options for couples unable to conceive who undergo ART. Therefore, screening spermatozoal DNA may serve as an additional tool in precision medicine to identify and treat subtle male factor infertility.

Trial registration number

N/A

P-117 A novel method to select spermatozoa with the best morphokinetic characteristics and superior genomic integrity

Study question

Can an automated device based on membrane electrophoresis be used to select spermatozoa with superior morphokinetic characteristics and lower sperm chromatin fragmentation (SCF)?

Summary answer

Albeit at an expense of concentration, a membrane-electrophoretic device was able to isolate a proportion of spermatozoa with the highest motility, morphology, and genomic integrity.

What is known already

Conventional sperm selection based on density gradient centrifugation (DGC) can enhance the proportion of progressively motile spermatozoa; however, DGC methods are limited in their ability to select spermatozoa with higher genomic integrity. Membrane-based microfluidic technologies (MFSS) have already been used clinically to select for spermatozoa with a superior chromatin status; however, these methods are based on the intrinsic characteristics of motile spermatozoa capable of selecting themselves. By incorporating an extrinsic electrophoretic drive, membrane electrophoresis would overcome a limitation of progressive motility in the semen sample and be able to isolate viable gametes with better morphology and reduced SCF.

Study design, size, duration

From August 2020 to December 2021, semen samples from 68 men were evaluated by standard semen analysis and simultaneously processed by DGC or a novel membrane-electrophoretic sperm sorter (EPSS) to select for progressively motile spermatozoa. Concentration, motility, progressive motility, morphology, and SCF were measured and compared between raw, DGC-, and EPSS-processed specimens.

Participants/materials, setting, methods

Fresh ejaculates were evaluated by standard semen analysis according to WHO 2021 criteria. Following complete liquefaction, specimens were divided into two equal aliquots for DGC and EPSS sorting. SCF was assessed by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay under fluorescent microscopy; at least 500 spermatozoa were evaluated for each specimen with a normal threshold of ≤ 15%.

Main results and the role of chance

A total of 68 men with an average age of 38.1±6 years had the following average semen parameters: volume of 3.1±1 mL, concentration of 58.2±33 x106/mL, 43.3±9% motility, 40.5±9% forward progression motility, and a normal morphology of 2.9±0.8%. When comparing the final parameters between the EPSS and DGC methods, despite a reduced sperm concentration (7.3±9 x106/mL vs 45.0±36 x106/mL, P&lt;0.0001, respectively), EPSS was highly selective for motile spermatozoa, yielding significantly higher motility (93.1±16% vs. 86.8±15% P&lt;0.0001) and forward progressive motility (92.3±17% vs 85.2±15%, P&lt;0.0001). Despite an overall lower sperm recovery rate (21.4±25% vs 75.4±17%, P&lt;0.0001), normal morphology improved to 3.4±0.8% (P&lt;0.0001) after EPSS but remained unchanged in the DGC-processed sample. Although both EPSS and DGC improved SCF from 12.2±9% in the raw specimen to 4.8±6% and 6.6±7% (P &lt; 0.0001), respectively, EPSS outperformed DGC (P &lt; 0.05). Moreover, the DGC method took up to 60 min to process, whereas the EPSS technique took a total of 6 min.

Limitations, reasons for caution

The selection of spermatozoa by EPSS is a promising technique to isolate progressively motile spermatozoa with enhanced morphology and superior chromatin integrity, albeit at a lower concentration. This is a preliminary study; the benefit and safety of this method must be further demonstrated by insemination or IVF treatment.

Wider implications of the findings

A membrane electrophoresis device may be a viable alternative method to MFSS to identify spermatozoa with superior morphokinetic characteristics and intact chromatin. Moreover, incorporating an automated device can reduce gamete processing time while minimizing labor costs and inter-operator errors.

Trial registration number

N/A

P-107 A Novel Sperm Selection Technique for Embryos of the Desired Sex

Study question

Can a novel sperm selection technique (GST) yield higher rates of embryos and offspring of the desired sex in couples undergoing ICSI with PGT-A?

Summary answer

GST consistently enriched spermatozoa, resulting in a higher proportion of embryos and offspring of the desired sex without impairing clinical outcomes or offspring health.

What is known already

Although various methods to select sex-specific spermatozoa have been proposed over the years, many of these techniques have been shown to have varying degrees of success in addition to being time-consuming and costly. Moreover, the use of fluorescence and electrical charges in some of these methods has raised concerns about their potential contribution to congenital malformations. Here, we tested a novel sperm selection method aimed at achieving a higher proportion of embryos of the desired sex, without compromising clinical outcome or offspring health.

Study design, size, duration

Over a 6-year period, ejaculates from male partners of couples (n = 109) undergoing ICSI with PGT-A were processed using GST to enrich spermatozoa for the couples’ preferred sex. Standard sperm processing was carried out for couples undergoing ICSI exclusively to assess conceptus aneuploidy, comprising the control group (n = 1,261). The proportion of male and female spermatozoa in the initial and selected specimens, PGT-A results, and ICSI outcomes were compared between the two groups.

Participants/materials, setting, methods

A total of 1,370 couples were treated in 2,483 ICSI cycles. Standard sperm processing was performed for 1,261 couples who did not have an offspring sex preference. For 109 consenting couples, GST was used to enrich spermatozoa for their desired sex (IRB 1306014043). To confirm sex enrichment, ≥1,000 sperm cells were screened by fluorescent in-situ hybridization (FISH) for 9 chromosomes. The couples’ PGT-A results and ICSI outcomes were compared between the control and GST cohorts.

Main results and the role of chance

For the control cohort (n = 1,261), ejaculates were processed in the standard fashion. Spermatozoa sex ratio was unaffected. These couples (maternal age, 37.1±4yrs; paternal age, 39.1±6yrs) underwent 2,356 ICSI cycles (1.2±1), yielding an 80.9% fertilization rate (14,830/18,321). PGT-A results confirmed that 46.6% (n = 760) of their embryos were female and 53.4% (n = 872) were male. They achieved a 76.3% (725/950) implantation rate and a 64.9% (617/950) clinical pregnancy rate resulting in 569 healthy deliveries (48% female, 52% male).

From the study cohort (n = 109), 60 couples desired a female and 49 desired a male child. Those who desired female offspring (maternal age, 37.9±4yrs; paternal age, 40.8±6yrs) obtained an 81.6% sperm sex enrichment, per FISH. They underwent 74 ICSI cycles and achieved a 77.6% (592/763) fertilization rate resulting in 78.1% (235/301) female embryos that generated a 79.3% (23/29) implantation rate, yielding 16 singleton deliveries of healthy female offspring that are developing normally.

The 49 couples (maternal age, 37.6±3yrs; paternal age, 40.8±5yrs) preferring male offspring obtained an 80.8% sperm sex enrichment. They underwent 53 ICSI cycles and achieved a 74.7% (481/644) fertilization rate with an equivalent proportion of male embryos (231/292, 79.1%). Their implantation rate was 90.9% (20/22), yielding 14 healthy male singletons, all developing normally.

Limitations, reasons for caution

Although our sperm sex selection method does not guarantee offspring of a specific sex, it allowed couples participating in the study to obtain a greater proportion of conceptuses of their desired genotype. This method does not aim to replace PGT-A, but rather reduce embryo wastage.

Wider implications of the findings

Semen specimens processed by GST yielded satisfactory fertilization and embryo development, comparable to those from the control cohort. Moreover, offspring health was not negatively affected. These encouraging findings indicate that our method is safe and can consistently enrich for the desired embryo sex in a reliable and ethically palatable manner.

Trial registration number

n/a

O-215 Embryo developmental competence of de novo male gametes in a novel three-dimensional culture

Study question

Are de novo gametes generated from mouse embryonic stem cells (mESCs) in a novel three-dimensional (3D) culture system capable of supporting full preimplantation development?

Summary answer

A novel 3D culture system yielded de novo male gametes capable of fertilizing an oocyte and supporting full preimplantation development.

What is known already

In regenerative medicine, several 3D culture systems have been shown to be capable of producing functional tissue implants. In reproductive biology, recent studies have reported preliminary success in generating functional de novo gametes through soft-agar culture and testicular organoids, in the mouse model. However, a heterologous transplantation technique is required to obtain functional gametes.

Study design, size, duration

mESCs were first cultured on a gelatin-coated 6-well plate with fibroblasts in monolayer and later spherified using sodium alginate. Spheres were submerged in specifically designed conditioned media to encourage differentiation of the mESCs into germ-like cells. Over the course of differentiation, cells were assessed for germ cell differentiation biomarkers. Considering that normal spermatogenesis occurs in 30 days, utilization of the de novo gametes was planned for days 15, 22, 29, and 36.

Participants/materials, setting, methods

mESCs were differentiated by submerging the spheres in EpiLC medium containing Activin A, bFGF, and KSR for 3 days followed by PGCLC medium containing BMP4, LIF, SCF, and EGF for up to 36 days. Differentiation was assessed for markers DAZL (spermatogonium), VASA (spermatocyte), BOULE (post-meiotic stage), and acrosin (spermatid). Differentiated cells were then injected into oocytes and activated by calcium ionophore. Embryo development was monitored in a time-lapse incubator.

Main results and the role of chance

Expression of DAZL in 20% and VASA in 15% of the cells at day 3 demonstrated progression into spermatogenesis. On day 10, DAZL and VASA were assessed again, revealing increases to 45% and 18%. A small proportion of cells expressed post-meiotic biomarkers, BOULE (1%) and acrosin (2%). On day 15, VASA expression plateaued at 17%, BOULE expression peaked at 10%, and acrosin reached 5%. On day 22, expression of VASA increased slightly to 19%, BOULE decreased to 8%, and acrosin peaked at 7%. On day 29, VASA expression peaked at 20%, acrosin expression remained stable at 7%, and BOULE expression dropped to 2%. On day 36, VASA was still expressed at 13%, and few cells expressed acrosin (1%); there was complete loss of BOULE expression. 

Our mouse ICSI control achieved 89.2% fertilization and 77.8% blastocyst rates. De novo gametes were injected into oocytes on days 15, 22, 29, and 36, achieving fertilization rates of 35.0%, 61.1%, 81.8%, and 75.0%, respectively. Correspondently, hatching blastocysts were obtained at rates of 5.0%, 16.7%, 36.4%, and 8.3%, respectively.

Limitations, reasons for caution

Despite the ability to fertilize normally, the blastulation rate remained suboptimal. Most importantly, the ability to generate live offspring still needs to be documented.

Wider implications of the findings

Our novel 3D differentiation model can generate functional gametes and is aimed at obviating the need for allo-/xeno-geneic transplantation. If reproducibility and the ability to obtain healthy offspring are confirmed, this method may represent a tool for achieving neogametogensis in mammals.

Trial registration number

N/A

O-120 Embryo ranking agreement between embryologists and AI algorithms

Study question

What is the level of agreement between different AI algorithms and embryologists when ranking blastocysts?

Summary answer

In general, embryologists have a stronger level of agreement with each other, whereas AI algorithms differ greatly between embryologists and among each other.

What is known already

Previous studies comparing agreement among embryologists ranking embryos have shown moderate to high inter-and intra-agreement levels. To our knowledge, this is the first study that endeavors to evaluate the level of agreement between different AI algorithms and embryologists in regard to ranking embryo quality.

Study design, size, duration

Study data consisted of time-lapse images of 800 embryos from 100 patients (8 embryos each). All embryos were created from fresh oocytes retrieved at a single center between 2019 and 2020 and fertilized using ICSI. They were cultured in TLM incubators (Vitrolife, Sweden) and developed for 120 hours. The cohort included at least 8 embryos that started to blastulate (sTB) before 120 hours post-fertilization (HPF–ICSI). Patients older than 38 years were excluded. 

Participants/materials, setting, methods

Five international embryologists ranked embryos using single images; three also ranked embryos using TLM videos. Eight international AI companies anonymously ranked the embryos using AI models; half used single images while the others used full videos. The Kendal Tau statistic was used to determine the agreement level between the ranking methods; -1 denotes 100% disagreement and 1 denotes perfect agreement. The pair-wise agreement in selecting the top-one and top-two embryos was compared across all methods.

Main results and the role of chance

The embryologists had relatively high degree of agreement in the overall ranking of 100 cycles (average K-t=0.70), slightly lower than the inter-embryologist agreement when using a single image or video (average K-t=0.78). Overall agreement between embryologists and the AI algorithms was significantly lower (average K-t=0.53) and similar to inter-AI algorithm agreement (average K-t=0.47). Notably, two of the eight algorithms had a very low agreement with other ranking methodologies (average K-t=0.05).

The average agreement in selecting the best-quality embryo (1/8 in 100 cycles, expected agreement by random chance, 12.5% CI95:6-19%) was 59.5% among embryologists and 40.3% for six AI algorithms, for the two algorithms with the low overall agreement, the incidence of the agreement was 11.7%.

Agreement on selecting the same top-two embryos/cycle (expected agreement by random chance, 25.0% CI95:17-32%) was 73.5% among embryologists and 56.0% among AI methods excluding two discordant algorithms, which had an average agreement of 24.4%, the expected range of agreement from random chance.

Intra-embryologist ranking agreement (single image vs. video) was 71.7% and 77.8% for single and top-two embryos, respectively.

Analysis of average raw scores indicated cycles with low diversity of embryo quality generally resulted in lower overall agreement between the methods (embryologists and AI models).

Limitations, reasons for caution

Given the selection process for cycles and the corresponding embryos, the ground truth cannot be assertained as no implantation or pregnancy outcome was assessed or compared. Although this study can identify agreement between different ranking methods, it can not determine which assessment method is correct.

Wider implications of the findings

Our results suggest that the AI method used to assign relative embryo quality may result in a significantly different selection and, presumably, outcome. Further studies should evaluate the source of the disagreement in embryos for which the outcome is known.

Trial registration number

N/A

O-311 Evaluating the Reproductive Potential of Azoospermic Men by Profiling the Genome of Surgically Retrieved Spermatozoa

Study question

Can whole exome sequencing of surgically retrieved spermatozoa from azoospermic men pinpoint mutations related to the etiology of their infertility and ability to support pregnancy?

Summary answer

Identifying key germline mutations involved in spermatogenesis helps explain reproductive failure, regardless of the etiology of the azoospermia.

What is known already

Azoospermia accounts for approximately 15% of male factor infertility cases. Although it can be caused by pre-testicular factors, the most recognized forms are testicular and post-testicular. Post-testicular azoospermia is mainly attributed to a mechanical obstruction, whereas testicular azoospermia, the most challenging form, is characterized by scattered functional germinal epithelia that may fail to support the meiotic process during sperm development. To elucidate the etiology of this condition, genetic studies on somatic cells have been carried out. Here, we perform whole exome sequencing (WES) on surgically retrieved spermatozoa to preferentially detect germline mutations that may be passed on to offspring.

Study design, size, duration

Over 3 years, we recruited patients undergoing epididymal sperm aspiration for acquired obstructive azoospermia (OA; n = 19) or testicular biopsy for nonobstructive azoospermia (NOA; n = 11). Eight men were included as fertile controls. Copy number variants (CNVs) and gene mutation profiles were obtained through WES and compared between the OA and NOA cohorts, followed by sub-analyses within those two categories according to whether they generated a clinical pregnancy (fertile) or not (infertile), while controlling for maternal age.

Participants/materials, setting, methods

Spermatozoal DNA was extracted and amplified from the surgically retrieved specimens (concentration, 742±520 ng/ul; quality, 1.7±0.1 nm). CNVs and gene mutations were detected using CLC Genomic Server 9.0. Genes were considered duplicated or deleted when the read depth was &gt;1.5 or &lt; 0.5 times the median read depth in the control. Common mutations were compared between the OA and NOA cohorts, as well as according to the couples’ clinical outcomes. Female partners had negative infertility workups.

Main results and the role of chance

Of 30 men (paternal age, 42.3±7yrs), 19 OA men underwent epididymal sperm retrievals (concentration, 1.1±4x106/ml, 9±12% motility), while 11 NOA men underwent testicular biopsies (concentration, 0.03±0.4x106/ml, 0.5±1% motility). WES did not indicate a significant difference in sperm aneuploidy between the two etiologies (OA, 1.7%; NOA, 1.8%) compared to the control (1.1%).

In OA patients, only 3 housekeeping-related genes were deleted, while in the NOA cohort, 5 genes involved in RNA transcription (POLR2L), apoptosis (AP5M1), and basic spermiogenic functions (AP1S2, AP1G2, APOE) were deleted.

OA patients and their partners (maternal age, 36.8±4yrs) underwent 19 ICSI cycles resulting in a delivery rate of 47.4% (9/19). Those able to reproduce (n = 9) shared a mutation in ZNF749, specifically affecting sperm production. The infertile men (n = 10) all shared a PRB1 deletion, controlling essential DNA replication.

NOA men and their partners (maternal age, 38.2±2yrs) underwent 11 ICSI cycles, yielding a delivery rate of 72.7% (8/11). The fertile men (n = 8) all shared a MPIG6B deletion, involved in stem cell lineage differentiation. All of their infertile counterparts (n = 3) presented gene deletions not only involved in spermato/spermio-genesis (n = 4) but, most importantly, also superimposed with those encoding early embryonic development (MBD5, CCAR1, PMEPA1, POLK, REC8, REPIN1, MAPRE3, ARL4C).  

Limitations, reasons for caution

Although maternal age was controlled for, confounding factors related to the female partner cannot entirely be excluded. While men unable to reproduce shared common gene mutations providing information about their condition, these findings still need to be confirmed in larger observations.

Wider implications of the findings

By performing WES, we were able to identify specific mutations associated with compromised embryo developmental competence of surgically retrieved spermatozoa. DNA sequencing technologies help identify gametes capable of sustaining a pregnancy even in the most severe form of male infertility, laying the groundwork for precision medicine in this field.

Trial registration number

N/A

P-111 Spermiogenic maturation in relation to sperm genomic integrity throughout the epididymis

Study question

Which portion of the epididymis yields spermatozoa with the highest chromatin integrity and embryo developmental competence?

Summary answer

Spermatozoa retrieved from the distal portion of the epididymis retains the highest chromatin integrity, characterized by higher fertilization, implantation, and clinical pregnancy rates.

What is known already

Surgical sperm retrieval from the proximal male reproductive tract has proven to be an effective treatment for couples with recurrent pregnancy loss due to high DNA fragmentation in the ejaculate. Although spermatozoa retrieved directly from the germinal epithelium displays the highest genomic integrity, epididymal spermatozoa maintain a similar DNA integrity profile but yield higher fertilization and pregnancy rates. Although the caput is the preferred site for sperm aspiration procedures in the epididymis, it is unclear which epididymal region yields the best-quality gametes.

Study design, size, duration

Over a 10-year period, we identified 51 obstructive azoospermic (OA) men who underwent surgical sperm retrieval. These men were grouped according to the different epididymal regions from which their spermatozoa were obtained. Sperm chromatin fragmentation (SCF) was assessed and compared among these groups. The epididymal spermatozoa were then used for ICSI cycles. Fertilization and clinical outcomes were compared among the epididymal regions. All female partners (≤37 years old) had negative infertility workups.

Participants/materials, setting, methods

Epididymal spermatozoa were retrieved from the caput (n = 39), corpus (n = 8), and cauda (n = 4) regions. SCF was assessed by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, with a normal threshold of ≤ 15%. Unpaired t and Fisher’s exact tests were used to compare the SCF as well as ICSI and pregnancy outcomes according to the epididymal sperm source. P &lt; 0.05 was considered statistically significant.

Main results and the role of chance

A total of 51 men were categorized based on the site of spermatozoa retrieval: caput, corpus, and cauda. Maternal age was comparable among all three groups (37.9±5, 37.3±4, and 38±3, respectively). Sperm concentration was 23.9±30x106/ml (caput), 24.3±30x106/ml (corpus), and 29.3±36x106/ml (cauda), with 10.8±15% (caput), 14.3±20%(corpus), and 15.2±13% motility (cauda). Average oocytes injected per group was 13.3, 12.3, and 13.2, respectively. Average SCF scores were 19.8%, 9.2% (P &lt; 0.05), and 8.4% (P &lt; 0.05), respectively. The fertilization rates rose from 69.0% in the caput to 78.6% in the corpus and 86.2% (P &lt; 0.05) in the cauda. Implantation rates followed a similar trend: 35.3% in the caput and 44.4% and 50.1% in the corpus and cauda, respectively. In cycles using caput epididymal spermatozoa, there was a 52.9% delivery rate with a 5.5% pregnancy loss rate. Cycles using corpus epididymal sperm showed a 75.0% delivery rate with no pregnancy loss. Finally, cycles using spermatozoa from the cauda resulted in a 100% delivery rate.

Limitations, reasons for caution

Although spermatozoa retrieved from the cauda epididymis has superior genomic integrity and yielded satisfactory clinical outcomes, this approach may be restricted to patients with obstructive azoospermia. While we attempted to control for an eventual confounding female factor, it cannot be entirely ruled out.

Wider implications of the findings

The epididymis plays an important role in sperm maturation; epididymal spermatozoa retain adequate chromatin integrity as demonstrated by the fertilization and pregnancy rates achieved with sperm retrieved from the cauda region. Confirmation of these findings in larger studies may help determine the most favorable site for epididymal sperm retrieval.

Trial registration number

Not applicable

P-797 Benefit of Replicating Mammalian Gametes

Study question

Can haploid parthenogenetic and androgenetic embryos generate haploid embryonic stem cells (haESCs) and function as respective oocytes and spermatozoa?

Summary answer

Haploid embryos generated blastocysts capable of yielding haESCs. Haploid blastomeres of both sexes served as multiple copies of gamete substitutes.

What is known already

Although creating diploid digyneic or dispermic embryos through nuclear transfer is possible, the conceptuses rarely achieve normal preimplantation development due to unbalanced epigenomes, demonstrating the requirement of both parental epigenomes in the course of embryogenesis. Haploid parthenogenetic embryos can be achieved by inducing calcium oscillations of a metaphase II oocyte, while the paternal counterpart can be generated through the insemination of enucleated oocytes. These embryos may serve to generate haESCs for heterozygosity identification and can be used for reproductive purposes in animal models.

Study design, size, duration

To generate parthenogenetic embryos, metaphase II oocytes from B6D2F1 mice were artificially activated. Androgenetic embryos were generated from the insemination of enucleated oocytes. Haploid embryos were cultured to blastocysts and seeded on feeder cells (MEF) to derive haESCs. Haploid blastomeres from 8-cell embryos of either sex were isolated and used as artificial gametes; artificial oocytes were generated by grafting a parthenogenetic blastomere to an enucleated recipient oocyte. Androgenetic blastomeres were used as male gametes.

Participants/materials, setting, methods

Parthenogenetic embryos were generated by exposing metaphase II oocytes to calcium ionophore. Another cohort of B6D2F1 oocytes were enucleated and underwent piezo-ICSI to generate androgenetic embryos. Sendai-virus–mediated nuclear transfer was performed using parthenogenetic blastomeres as donor nucleuses to generate artificial oocytes and subsequently fertilized. Androgenetic blastomeres were used as sperm substitutes by fusion with an intact oocyte to generate zygotes. Control embryos were generated by piezo-actuated ICSI. Developmental characteristics were recorded by time-lapse microscopy.

Main results and the role of chance

A total of 129 oocytes were parthenogenetically activated by calcium ionophore, and 119 developed a female pronucleus. Androgenetic embryos were generated from the insemination of 375 ooplasts; 317 developed a male pronucleus. The monopronuclear appearance of haploid embryos of both sexes was comparable to the fertilization of control at 90.7%.

Haploid embryo development for both sexes up to the 4-cell stage matched the control. However, from the 8-cell stage onward, parthenogenetic and androgenetic embryos cleaved at a lower rate compared to the control at 76.4%, 59.3% and 92.7% (P &lt; 0.0001), respectively. The haploid genome affected the rate of compaction at 73.6%, 55.3%, and 89.2% (P&lt;0.0001), respectively, and the rate of blastulation at 27.8%, 11.2%, and 80.8% (P&lt;0.00001) respectively. Androgenetic embryos showed delayed cleavage from the 4-cell stage onward, while the parthenogenetic counterparts had similar morphokinetics to the control.

A total of 20 parthenogenetic and 18 androgenetic blastocysts were plated on MEF, yielding 5 parthenogenetic and 3 androgenetic haESC lines. Both haESCs yielded beating cardiomyocytes on day 10 of differentiation while maintaining haploidy.

The utilization of haploid pseudo blastomeres as gametes yielded 93 reconstructed biparental embryos that resulted in 71 blastocysts (76.3%). Time-lapse morphokinetics were comparable to the control.

Limitations, reasons for caution

Haploid embryos developed to blastocysts at a remarkably lower rate than the control, particularly the androgenotes; however, they can yield pluripotent haESCs capable of differentiation in the mesoderm and subsequent cardiogenesis prone to self-diploidization. Once this system is replicated in humans, the role of the centrosome needs to be investigated.

Wider implications of the findings

Our study has demonstrated the feasibility of propagating both male and female genomes from single gametes for reproductive applications. Indeed, once a stable culture of haESCs is achieved, genotyped pluripotent haESCs can be used to help identify heterozygosity for inherited disorders.

Trial registration number

N/A

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 &lt; 0.00001) and embryo implantation rates (34.2%) (P &lt; 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 &lt; 0.0001), 2.8% to 24.7% (P &lt; 0.00001), 8.4% to 38.8% (P &lt; 0.0001), and 1.2% to 28.6% (P &lt; 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.

P-478 Deleterious influence of cyclophosphamide on primordial follicles derives from increased DNA damage and reduced proliferation in xenotransplanted human ovarian tissue

Study question

What are the acute effects of cyclophosphamide (Cp) on primordial follicles (PrFs) in human ovarian tissue?

Summary answer

Administration of Cp damages PrFs via DNA fragmentation and results in reduced proliferation with no increase in PrF activation markers.

What is known already

Alkylating agents are highly gonadotoxic, and in cases where freezing oocytes, embryos, or ovarian tissue is impractical, a better understanding of the underlying damage mechanism could enable development of fertoprotective approaches (1). Studies from different groups suggest conflicting mechanisms of ovarian damage, with either PrF activation (2) or cell damage and apoptosis (3-4) proposed as drivers of PrF depletion. Few studies have examined this question using human tissue. We performed xenografts using ovarian tissue from a 17-month-old girl to ensure a graft with plentiful PrFs to test the acute effect of Cp.

Study design, size, duration

Cross-sectional study.

We utilized a xenotransplantation model in which human ovarian tissue is co-transplanted with endothelial cells (ECs) into immunocompromised mice (NSG) (5). Three weeks after xenotransplantation, time 0, intraperitoneal (IP) injection of (saline/Cp) was followed by an IP injection of ethynyl-deoxyuridine (Edu), at 0 and 24 hours, followed by 5-chloro-2′-deoxyuridine (CldU), at 48 and 72 hours. Grafts were harvested at 96 hours.

Participants/materials, setting, methods

We co-xenotransplanted human ovarian cortical tissue from a 17-month-old girl, cryopreserved for fertility preservation, into immunocompromised mice. After 3 weeks, Cp (75mg/Kg)/saline was administered IP. Mice were then sequentially injected with EdU, followed by CldU (both at 100mg/kg for 2 days) 24 hours apart. Twenty-four hours later, mice were sacrificed and xenografts were harvested and sectioned. Slides were stained for EdU, CldU, VASA, γ-H2AX, FOXO3a, and 4',6-Diamidino-2-Phenylindole-Dilactate (DAPI) and imaged using a confocal microscope.

Main results and the role of chance

We used anti-VASA staining to evaluate oocyte morphology, confirming that chemotherapy was not sterilizing; we counted 76.5% of morphologically normal PrF in the control group (Ctrl) (130/170) and 35.1% (13/37) in the Cp group. In the Ctrl group, 11% stained positively for DNA fragmentation using anti-γ-H2AX, whereas 43% were positive in the Cp group (p = 0.0073). To evaluate activation, we stained for FOXO3a in the oocyte nucleus. No difference was found between the groups: 52.4% (74/144) versus 44.6% (37/83) in Ctrl versus Cp, respectively. Interestingly, when comparing EdU incorporation, the Ctrl group had higher incorporation at 72%, versus the Cp group with 40% of incorporation (p = 0.0485), and no difference was found with CldU incorporation: Ctrl 22% versus 27% in the Cp group, respectively (P = 0.6960).

Limitations, reasons for caution

We measured acute effects, DNA fragmentation, and proliferation, at five days post-Cp administration; however, this falls short of evaluating processes that appear later (fibrosis and neovascularization). Also, the results may partly stem from the patient’s young age. Repeating the experiment using adult-derived tissue might yield different results.

Wider implications of the findings

A better understanding of both the timeline and underlying mechanisms that contribute to chemotherapy-related gonadotoxicity could diminish the damage and depletion of the ovarian reserve (PrF). These results provide evidence that direct damage to PrFs, and not increased activation, contributes to gonadotoxicity in the acute phase following administration of Cp.

Trial registration number

NA

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 &gt; 1 and a P-value of &lt; 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 &lt; 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 &lt; 0.001), CPR (36.5% vs. 5.3%; P &lt; 0.0001), and ongoing/delivery rates (33.8% vs. 4.1%; P &lt; 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 &lt; 0.05), CPR (68.4% vs. 4.2%; P &lt; 0.0001), and ongoing/delivery rates (57.1% vs. 4.2%; P &lt; 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 &lt; 0.01), CPR (25.5% vs. 6.1%; P &lt; 0.01), and ongoing/delivery rates (23.6% vs. 3.0%; P &lt; 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  &lt;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

Chronic superphysiologic AMH promotes premature luteinization of antral follicles in human ovarian xenografts

Anti-Müllerian hormone (AMH) is produced by growing ovarian follicles and provides a diagnostic measure of reproductive reserve in women; however, the impact of AMH on folliculogenesis is poorly understood. We cotransplanted human ovarian cortex with control or AMH-expressing endothelial cells in immunocompromised mice and recovered antral follicles for purification and downstream single-cell RNA sequencing of granulosa and theca/stroma cell fractions. A total of 38 antral follicles were observed (19 control and 19 AMH) at long-term intervals (>10 weeks). In the context of exogenous AMH, follicles exhibited a decreased ratio of primordial to growing follicles and antral follicles of increased diameter. Transcriptomic analysis and immunolabeling revealed a marked increase in factors typically noted at more advanced stages of follicle maturation, with granulosa and theca/stroma cells also displaying molecular hallmarks of luteinization. These results suggest that superphysiologic AMH alone may contribute to ovulatory dysfunction by accelerating maturation and/or luteinization of antral-stage follicles.

Non-contact ultrasound oocyte denudation

Cumulus removal (CR) is a central prerequisite step for many protocols involved in the assisted reproductive technology (ART) such as intracytoplasmic sperm injection (ICSI) and preimplantation genetic testing (PGT). The most prevalent CR technique is based upon laborious manual pipetting, which suffers from inter-operator variability and therefore a lack of standardization. Automating CR procedures would alleviate many of these challenges, improving the odds of a successful ART or PGT outcome. In this study, a chip-scale ultrasonic device consisting of four interdigitated transducers (IDT) on a lithium niobate substrate has been engineered to deliver megahertz (MHz) range ultrasound to perform denudation. The acoustic streaming and acoustic radiation force agitate COCs inside a microwell placed on top of the LiNbO₃ substrate to remove the cumulus cells from the oocytes. This paper demonstrates the capability and safety of the denudation procedure utilizing surface acoustic wave (SAW), achieving automation of this delicate manual procedure and paving the steps toward improved and standardized oocyte manipulation.

Clinical pregnancy resulting from intracytoplasmic sperm injection of prematurely ovulated oocytes retrieved from the posterior cul-de-sac

Objective

To report a clinical pregnancy resulting from intracytoplasmic sperm injection of prematurely ovulated oocytes retrieved from the posterior cul-de-sac.

Design

Case report.

Setting

Academic center.

Patient(s)

A 40-year-old nulligravid woman underwent ovarian stimulation for in vitro fertilization (IVF). Daily injections of gonadotropin-releasing hormone antagonist were initiated on cycle day 8. A 10,000 IU dose of human chorionic gonadotropin was administered on cycle day 15 to trigger follicular maturation. The estradiol and luteinizing hormone levels on the trigger day were 1528 pg/mL and 2.4 mIU/mL, respectively. The patient underwent oocyte retrieval 35 hours after the trigger. Transvaginal sonography at the time of the retrieval revealed a large pocket of free fluid in the posterior cul-de-sac. Only 3 follicles measuring 10–12 mm were noted in both ovaries. No lead follicles were visualized.

Intervention(s)

Aspiration of free fluid from the posterior cul-de-sac.

Main Outcome Measure(s)

Clinical pregnancy.

Result(s)

The fluid in the posterior cul-de-sac was aspirated, and 3 mature oocytes were retrieved. Aspiration of the smaller ovarian follicles measuring 10–12 mm did not yield oocytes. All mature oocytes retrieved from the posterior cul-de-sac were fertilized with intracytoplasmic sperm injection. Three cleavage-stage embryos were transferred 3 days later. A single intrauterine pregnancy with cardiac activity was confirmed at a gestational age of 7 weeks.

Conclusion(s)

In the setting of premature ovulation, aspiration of free fluid from the posterior cul-de-sac can result in the retrieval of mature oocytes, which may result in clinical pregnancies.

Comparison of fresh and frozen ejaculated spermatozoa in sibling oocyte recipient cycles

RESEARCH QUESTION

Do IVF and intracytoplasmic sperm injection cycles using fresh and frozen ejaculated spermatozoa result in similar pregnancy outcomes in couples with non-male factor infertility?

DESIGN

Retrospective cohort study; patients undergoing donor egg recipient cycles, in which oocytes from a single ovarian stimulation were split between two recipients, were reviewed. Two recipients of oocytes from a single donor were paired and categorized based on the type of ejaculated spermatozoa (fresh/frozen). Outcomes included delivery rate, implantation, pregnancy, pregnancy loss and fertilization rates.

RESULTS

Of the 408 patients who received oocytes from a split donor oocyte cycle, 45 pairs of patients used discrepant types of ejaculated spermatozoa and were included in the study. Fertilization rate: fresh (74.8%); frozen (68.6%) (P = 0.13). Pregnancy rate: fresh (76%); frozen (67%); delivery rate: fresh (69%); frozen (44%); implantation rate was significantly higher: fresh (64%); frozen (36%) (P = 0.04). Rate of pregnancy loss was significantly higher in the frozen group compared with the fresh group (33% versus 5.9%, P = 0.013). Adjusted odds for delivery was 67% lower in the frozen group (95% CI 0.12, 0.89). Adjusted odds of pregnancy (adjusted OR 0.67, 95% CI 0.20, 2.27) and implantation (adjusted OR 0.5, 95% CI 0.12, 2.12) were not significantly different between the frozen and fresh sperm groups.

CONCLUSION

In this model that controls for oocyte quality by using paired recipients from the same donor, frozen ejaculated spermatozoa resulted in lower delivery rates than those using fresh spermatozoa.