The impact of microfluidics sperm processing on blastocyst euploidy rates compared with density gradient centrifugation: a sibling oocyte double-blinded prospective randomized clinical trial

OBJECTIVE

To compare the euploidy rates among blastocysts created from sibling oocytes injected with sperm and processed using microfluidics or density gradient centrifugation.

DESIGN

Sibling oocyte randomized controlled trial.

SETTING

Single university-affiliated infertility practice.

PATIENTS

A total of 106 patients aged 18-42 years undergoing fresh in vitro fertilization treatment cycles with preimplantation genetic testing between January 2021 and April 2022 contributed 1,442 mature oocytes, which were injected with sperm and processed using microfluidics or density gradient centrifugation.

INTERVENTION(S)

The sperm sample is divided and processed using a microfluidics device and density gradient centrifugation for injection into sibling oocytes.

MAIN OUTCOME MEASURE(S)

The primary outcome was the embryo euploidy rate. Secondary outcomes included fertilization, high-quality blastulation, and ongoing pregnancy rates.

RESULT(S)

The blastocyst euploidy rate per mature oocyte was not significantly different in the study group compared with the control group (22.9% vs. 20.5%). The blastocyst euploidy rate per biopsied embryo was also similar between the 2 groups (53.0% vs. 45.7%). However, the fertilization rate per mature oocyte injected was found to be significantly higher in the study group compared with the control group (76.0% vs. 69.9%). The high-quality blastulation rate per mature oocyte injected was similar between the 2 groups, as was the total number of embryos frozen. There were no differences in the number of participants with no blastocysts for biopsy or the number of participants with no euploid embryos between the 2 groups. Among the male factor infertility and recurrent pregnancy loss subgroups, there were no differences in euploidy rates, fertilization rates, blastulation rates, or total numbers of blastocysts frozen, although the study was underpowered to detect these differences. Seventy-seven patients underwent frozen embryo transfer; there were no significant differences in pregnancy outcomes between the 2 groups.

CONCLUSION(S)

Microfluidics processing did not improve embryo euploidy rates compared with density gradient centrifugation in this sibling oocyte study, although fertilization rates were significantly higher.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04744025.

Genomic aspects in reproductive medicine

Infertility is a complex disease characterized by extreme genetic heterogeneity, compounded by various environmental factors. While there are exceptions, individual genetic and genomic variations related to infertility are typically rare, often family-specific, and may serve as susceptibility factors rather than direct causes of the disease. Consequently, identifying the cause of infertility and developing prevention and treatment strategies based on these factors remain challenging tasks, even in the modern genomic era. In this review, we first examine the genetic and genomic variations associated with infertility, and subsequently summarize the concepts and methods of preimplantation genetic testing in light of advances in genome analysis technology.

Genetic mechanisms of fertilization failure and early embryonic arrest: a comprehensive review

BACKGROUND

Infertility and pregnancy loss are longstanding problems. Successful fertilization and high-quality embryos are prerequisites for an ongoing pregnancy. Studies have proven that every stage in the human reproductive process is regulated by multiple genes and any problem, at any step, may lead to fertilization failure (FF) or early embryonic arrest (EEA). Doctors can diagnose the pathogenic factors involved in FF and EEA by using genetic methods. With the progress in the development of new genetic technologies, such as single-cell RNA analysis and whole-exome sequencing, a new approach has opened up for us to directly study human germ cells and reproductive development. These findings will help us to identify the unique mechanism(s) that leads to FF and EEA in order to find potential treatments.

OBJECTIVE AND RATIONALE

The goal of this review is to compile current genetic knowledge related to FF and EEA, clarifying the mechanisms involved and providing clues for clinical diagnosis and treatment.

SEARCH METHODS

PubMed was used to search for relevant research articles and reviews, primarily focusing on English-language publications from January 1978 to June 2023. The search terms included fertilization failure, early embryonic arrest, genetic, epigenetic, whole-exome sequencing, DNA methylation, chromosome, non-coding RNA, and other related keywords. Additional studies were identified by searching reference lists. This review primarily focuses on research conducted in humans. However, it also incorporates relevant data from animal models when applicable. The results were presented descriptively, and individual study quality was not assessed.

OUTCOMES

A total of 233 relevant articles were included in the final review, from 3925 records identified initially. The review provides an overview of genetic factors and mechanisms involved in the human reproductive process. The genetic mutations and other genetic mechanisms of FF and EEA were systematically reviewed, for example, globozoospermia, oocyte activation failure, maternal effect gene mutations, zygotic genome activation abnormalities, chromosome abnormalities, and epigenetic abnormalities. Additionally, the review summarizes progress in treatments for different gene defects, offering new insights for clinical diagnosis and treatment.

WIDER IMPLICATIONS

The information provided in this review will facilitate the development of more accurate molecular screening tools for diagnosing infertility using genetic markers and networks in human reproductive development. The findings will also help guide clinical practice by identifying appropriate interventions based on specific gene mutations. For example, when an individual has obvious gene mutations related to FF, ICSI is recommended instead of IVF. However, in the case of genetic defects such as phospholipase C zeta1 (PLCZ1), actin-like7A (ACTL7A), actin-like 9 (ACTL9), and IQ motif-containing N (IQCN), ICSI may also fail to fertilize. We can consider artificial oocyte activation technology with ICSI to improve fertilization rate and reduce monetary and time costs. In the future, fertility is expected to be improved or restored by interfering with or supplementing the relevant genes.

Current Applications and Controversies in Preimplantation Genetic Testing for Aneuploidies (PGT-A) in In Vitro Fertilization

Preimplantation genetic testing for aneuploidy (PGT-A) has evolved over recent years, including improvements in embryo culture, biopsy, transfer, and genetic testing. The application of new comprehensive chromosome screening analysis has improved the accuracy in determining the chromosomal status of the analyzed sample, but it has brought new challenges such as the management of partial aneuploidies and mosaicisms. For the past two decades, PGT-A has been involved in a controversy regarding its efficiency in improving IVF outcomes, despite its widespread worldwide implementation. Understanding the impact of embryo aneuploidy in IVF (in vitro fertilization) should theoretically allow improving reproductive outcomes. This review of the literature aims to describe the impact of aneuploidy in human reproduction and how PGT-A was introduced to overcome this obstacle in IVF (in vitro fertilization). The article will try to analyze and summarize the evolution of the PGT-A in the recent years, and its current applications and limitations, as well as the controversy it generates. Conflicting published data could indicate the lacking value of a single biopsied sample to determine embryo chromosomal status and/or the lack of standardized methods for embryo culture and management and genetic analysis among other factors. It has to be considered that PGT-A may not be a universal test to improve the reproductive potential in IVF patients, rather each clinic should evaluate the efficacy of PGT-A in their IVF program based on their population, skills, and limitations.

Y chromosome AZFc microdeletion may have negative effect on embryo euploidy: a retrospective cohort study

BACKGROUND

Embryo aneuploidy is a main of principal reason of pregnancy loss, in vitro fertilization (IVF) failure and birth defects in offspring. Previous researchs have demonstrated that Y chromosome AZFc microdeletion was associated with reproduction outcomes, however, the relationship between Y chromosome AZFc microdeletion and embryo aneuploidy remains unexplored.

METHODS

This retrospective cohort study enrolled 513 patients with 603 cycles in the reproductive center of Nanjing Maternity and Child Health Care Hospital from January 1, 2016 to June 30, 2022. The study cohort was divided into two groups: the AZFc microdeletion group, comprising 53 patients and 58 cycles, and the control group, comprising 460 patients and 545 cycles. Statistical methods including restricted cubic spline and generalized estimating equation (GEE) were employed to evaluate the relationship between Y chromosome AZFc microdeletion and embryo euploidy.

RESULTS

294 and 2833 blastocysts were selected as AZFc microdeletion group and control group, respectively. Patients with Y chromosome AZFc microdeletion had significantly higher embryo aneuploid rate (33.0% vs. 27.3%, P < 0.05), lower rate of normal fertilization rate (81.5% vs. 90.3%, P < 0.05) and lower blastocysts formation rate (47.0% vs. 57.8%, P < 0.05) compared with the control group. However, no significant differences in pregnancy outcomes after euploid embryos transfer were observed between these two groups.

CONCLUSIONS

Our study underscored the association between Y chromosome AZFc microdeletion and an elevated risk of embryo aneuploidy. Before the conventional intracytoplasmic sperm injection (ICSI) treatment, couples with Y chromosome AZFc microdeletion should be apprised of the heightened susceptibility to embryo aneuploidy. Preimplantation genetic testing for aneuploidy (PGT-A) should be introduced for selection.

Epidemiology of sperm DNA fragmentation in a retrospective cohort of 1191 men

BACKGROUND

The scientific and clinical communities now recognize that sperm DNA integrity is crucial for successful fertilization, good embryo development, and offspring quality of life. Despite the apparent unanimity, this criterion is rarely evaluated in clinical practice. We evaluated the sperm DNA fragmentation index of nearly 1200 sperm samples and its connections based on the patient's age, body mass index, the season of sperm collection, geographical location, medical history, and addictive behaviors.

METHODS

A cohort of 1503 patients who were referred to the Royan Institute between July 2018 and March 2020 was examined. Only 1191 patient records with demographic data, complete semen analysis, and DNA fragmentation index measurements were included in the final cohort. Documents were classified, incorporated into statistical models, and analyzed.

RESULTS

The results confirmed previous findings that the sperm DNA fragmentation index was significantly higher in aging men. The sperm DNA fragmentation index and high DNA stainability levels were significantly higher in spring and summer samples than in those of other seasons. No correlation was found between semen DNA fragmentation index and patient body mass index, although the study cohort was significantly overweight. Contrary to what might be expected, we observed that the sperm DNA fragmentation index was higher in rural than in urban patients. Intriguingly, epileptic patients exhibited significantly higher sperm DNA fragmentation index levels.

DISCUSSION AND CONCLUSION

Age is the factor that is most strongly associated with sperm DNA fragmentation index levels. Our analysis of 1191 samples indicates that between the ages of 19 and 59, the sperm DNA fragmentation index increases by an average of 2% each year. Intriguingly, from an epidemiological perspective, the warm season (spring/summer) is associated with a higher sperm DNA fragmentation index in the study population, possibly due to the deleterious effect of temperature on sperm quality. Some neurological diseases, such as epilepsy, are associated with decreased sperm DNA integrity. This observation could be related to the iatrogenic effects of associated therapies. In the study cohort, body mass index did not appear to be correlated with the DNA fragmentation index.

Sperm and Oocyte Chromosomal Abnormalities

Gametogenesis, the process of producing gametes, differs significantly between oocytes and sperm. Most oocytes have chromosomal aneuploidies, indicating that chromosomal aberrations in miscarried and newborn infants are of oocyte origin. Conversely, most structural anomalies are of sperm origin. A prolonged meiotic period caused by increasing female age is responsible for an increased number of chromosomal aberrations. Sperm chromosomes are difficult to analyze because they cannot be evaluated using somatic cell chromosome analysis methods. Nevertheless, researchers have developed methods for chromosome analysis of sperm using the fluorescence in situ hybridization method, hamster eggs, and mouse eggs, allowing for the cytogenetic evaluation of individual sperm. Reproductive medicine has allowed men with severe spermatogenic defects or chromosomal abnormalities to have children. However, using these techniques to achieve successful pregnancies results in higher rates of miscarriages and embryos with chromosomal abnormalities. This raises questions regarding which cases should undergo sperm chromosome analysis and how the results should be interpreted. Here, we reviewed clinical trials that have been reported on oocyte and sperm chromosome analyses. Examination of chromosomal abnormalities in gametes is critical in assisted reproductive technology. Therefore, it is necessary to continue to study the mechanism underlying gametic chromosomal abnormalities.

ESHRE good practice recommendations on recurrent implantation failure

STUDY QUESTION

How should recurrent implantation failure (RIF) in patients undergoing ART be defined and managed?

SUMMARY ANSWER

This is the first ESHRE good practice recommendations paper providing a definition for RIF together with recommendations on how to investigate causes and contributing factors, and how to improve the chances of a pregnancy.

WHAT IS KNOWN ALREADY

RIF is a challenge in the ART clinic, with a multitude of investigations and interventions offered and applied in clinical practice, often without biological rationale or with unequivocal evidence of benefit.

STUDY DESIGN SIZE DURATION

This document was developed according to a predefined methodology for ESHRE good practice recommendations. Recommendations are supported by data from the literature, if available, and the results of a previously published survey on clinical practice in RIF and the expertise of the working group. A literature search was performed in PubMed and Cochrane focussing on 'recurrent reproductive failure', 'recurrent implantation failure', and 'repeated implantation failure'.

PARTICIPANTS/MATERIALS SETTING METHODS

The ESHRE Working Group on Recurrent Implantation Failure included eight members representing the ESHRE Special Interest Groups for Implantation and Early Pregnancy, Reproductive Endocrinology, and Embryology, with an independent chair and an expert in statistics. The recommendations for clinical practice were formulated based on the expert opinion of the working group, while taking into consideration the published data and results of the survey on uptake in clinical practice. The draft document was then open to ESHRE members for online peer review and was revised in light of the comments received.

MAIN RESULTS AND THE ROLE OF CHANCE

The working group recommends considering RIF as a secondary phenomenon of ART, as it can only be observed in patients undergoing IVF, and that the following description of RIF be adopted: 'RIF describes the scenario in which the transfer of embryos considered to be viable has failed to result in a positive pregnancy test sufficiently often in a specific patient to warrant consideration of further investigations and/or interventions'. It was agreed that the recommended threshold for the cumulative predicted chance of implantation to identify RIF for the purposes of initiating further investigation is 60%. When a couple have not had a successful implantation by a certain number of embryo transfers and the cumulative predicted chance of implantation associated with that number is greater than 60%, then they should be counselled on further investigation and/or treatment options. This term defines clinical RIF for which further actions should be considered. Nineteen recommendations were formulated on investigations when RIF is suspected, and 13 on interventions. Recommendations were colour-coded based on whether the investigations/interventions were recommended (green), to be considered (orange), or not recommended, i.e. not to be offered routinely (red).

LIMITATIONS REASONS FOR CAUTION

While awaiting the results of further studies and trials, the ESHRE Working Group on Recurrent Implantation Failure recommends identifying RIF based on the chance of successful implantation for the individual patient or couple and to restrict investigations and treatments to those supported by a clear rationale and data indicating their likely benefit.

WIDER IMPLICATIONS OF THE FINDINGS

This article provides not only good practice advice but also highlights the investigations and interventions that need further research. This research, when well-conducted, will be key to making progress in the clinical management of RIF.

STUDY FUNDING/COMPETING INTERESTS

The meetings and technical support for this project were funded by ESHRE. N.M. declared consulting fees from ArtPRED (The Netherlands) and Freya Biosciences (Denmark); Honoraria for lectures from Gedeon Richter, Merck, Abbott, and IBSA; being co-founder of Verso Biosense. He is Co-Chief Editor of Reproductive Biomedicine Online (RBMO). D.C. declared being an Associate Editor of Human Reproduction Update, and declared honoraria for lectures from Merck, Organon, IBSA, and Fairtility; support for attending meetings from Cooper Surgical, Fujifilm Irvine Scientific. G.G. declared that he or his institution received financial or non-financial support for research, lectures, workshops, advisory roles, or travelling from Ferring, Merck, Gedeon-Richter, PregLem, Abbott, Vifor, Organon, MSD, Coopersurgical, ObsEVA, and ReprodWissen. He is an Editor of the journals Archives of Obstetrics and Gynecology and Reproductive Biomedicine Online, and Editor in Chief of Journal Gynäkologische Endokrinologie. He is involved in guideline developments and quality control on national and international level. G.L. declared he or his institution received honoraria for lectures from Merck, Ferring, Vianex/Organon, and MSD. He is an Associate Editor of Human Reproduction Update, immediate past Coordinator of Special Interest Group for Reproductive Endocrinology of ESHRE and has been involved in Guideline Development Groups of ESHRE and national fertility authorities. D.J.M. declared being an Associate Editor for Human Reproduction Open and statistical Advisor for Reproductive Biomedicine Online. B.T. declared being shareholder of Reprognostics and she or her institution received financial or non-financial support for research, clinical trials, lectures, workshops, advisory roles or travelling from support for attending meetings from Ferring, MSD, Exeltis, Merck Serono, Bayer, Teva, Theramex and Novartis, Astropharm, Ferring. The other authors had nothing to disclose.

DISCLAIMER

This Good Practice Recommendations (GPR) document represents the views of ESHRE, which are the result of consensus between the relevant ESHRE stakeholders and are based on the scientific evidence available at the time of preparation. ESHRE GPRs should be used for information and educational purposes. They should not be interpreted as setting a standard of care or be deemed inclusive of all proper methods of care, or be exclusive of other methods of care reasonably directed to obtaining the same results. They do not replace the need for application of clinical judgement to each individual presentation, or variations based on locality and facility type. Furthermore, ESHRE GPRs do not constitute or imply the endorsement, or favouring, of any of the included technologies by ESHRE.

What Does Intracytoplasmic Sperm Injection Change in Embryonic Development? The Spermatozoon Contribution

The intracytoplasmic sperm injection (ICSI) technique was invented to solve severe male infertility due to altered sperm parameters. Nowadays, it is applied worldwide for the treatment of couple infertility. ICSI is performed with any available spermatozoon from surgery or ejaculated samples, whatever are the sperm motility, morphology or quantity. The aim of the present review was to study if embryo development and kinetics would be modified by (1) ICSI under the technical aspects, (2) the micro-injected spermatozoa in connection with male infertility. From published data, it can be seen that ICSI anticipates the zygote kinetics Furthermore, because fertilization rate is higher in ICSI compared to conventional in vitro fertilization (IVF), more blastocysts are obtained for clinical use in ICSI. Sperm and spermatozoa characteristics, such as sperm parameters, morphology and vitality, DNA content (levels of sperm DNA fragmentation, microdeletions, and chromosomal abnormalities), RNA content, epigenetics, and sperm recovery site (testicular, epididymis, and ejaculated), have an impact on fertilization and blastocyst rates and embryo kinetics in different ways. Even though ICSI is the most common solution to solve couples' infertility, the causes of male infertility are crucial in building a competent spermatozoa that will contribute to normal embryonic development and healthy offspring.

Globozoospermia: A Case Report and Systematic Review of Literature

PURPOSE

Globozoospermia is a genetic syndrome characterized by the presence of round-headed spermatozoa and infertility due to the inability of these spermatozoa to fertilize the oocyte. In this article, we present the clinical case of a young globozoospermic patient with a new, not yet described mutation of the DPY19L2 gene. We also performed a systematic review of the literature on gene mutations, the outcome of assisted reproductive techniques, and the risk of transmission of abnormalities to the offspring in patients with globozoospermia and made recommendations to offer a more appropriate clinical management of these patients.

MATERIALS AND METHODS

We performed a systematic search in the PubMed, Google Scholar, and Scopus databases from their inception to December 2021. The search strategy included the combination of the following Medical Subjects Headings (MeSH) terms and keywords: "globozoospermia", "round-headed spermatozoa", "round head spermatozoa", "intracytoplasmic sperm injection", "ICSI", "offspring", "child health", "assisted reproductive technique outcome". All the eligible studies were selected following the PECOS (Population, Exposure, Comparison/Comparator, Outcomes, Study design) model. The quality of included studies was assessed by applying the "Cambridge Quality Checklists".

RESULTS

The main genes involved in the pathogenesis of globozoospermia are DPY19L2, SPATA16, PICK1, GGN, SPACA1, ZPBP, CCDC62, and CCNB3 genes. Other genes could also play a role. These include C2CD6, C7orf61, CCIN, DNH17, DNH6, PIWIL4, and CHPT1. Globozoospermic patients should undergo ART to achieve fertility. In particular, intracytoplasmic sperm injection with assisted oocyte activation or intracytoplasmic morphologically-selected sperm injection appears to be associated with a higher success rate. Patients with globozoospermia should also be evaluated for the high rate of sperm aneuploidy which appears to influence the success rate of ART but does not appear to be associated with an increased risk of transmission of genetic abnormalities to offspring.

CONCLUSIONS

This systematic review summarizes the evidence on the gene panel to be evaluated, ICSI outcomes, and the health of the offspring in patients with globozoospermia. Evidence-based recommendations on the management of patients with globozoospermia are provided.

Risk of embryo aneuploidy is affected by the increase in sperm DNA damage in recurrent implantation failure patients under ICSI-CGH array cycles

This study investigates the relationship between sperm DNA damage in recurrent implantation failure (RIF) patients treated with comparative genomic hybridisation array-intracytoplasmic sperm injection (CGH array-ICSI) cycles and embryo aneuploidy screening. Forty-two RIF couples were selected. Sperm DFI was measured using TUNEL by flow cytometry. Two groups were defined as follows: (i) sperm with high DFI (> 20%); and (ii) low DFI (< 20%). Semen parameters, total antioxidant capacity (TAC), and malondialdehyde formation (MDA) were also measured in both groups. Following oocyte retrieval and ICSI procedure, blastomere biopsy was performed at the 4th day of development and evaluated with CGH-array. The high DFI group had a significant (p = 0.04) increase in the number of aneuploid embryos compared to the low one. According to Poisson regression results, the risk of aneuploidy embryos in the high DFI group was 55% higher than the low DFI group (RR = 1.55; 95% CI = 1.358-1.772). Moreover, chromosomal analysis showed an elevation of aneuploidy in chromosomes number 16 and 20 in the high DFI group compared to the low DFI group (p < 0.05). The high DFI in RIF patients may significantly affect the risk of aneuploidy embryos. Therefore, embryo selection by CGH-array should be considered for couples with high levels of sperm DNA fragmentation.

Switching to testicular sperm after a previous ICSI failure with ejaculated sperm significantly improves blastocyst quality without increasing aneuploidy risk

PURPOSE

The use of testicular sperm is confined to patients with azoospermia, but there is evidence to support its use in males with poor semen parameters and/or previous intracytoplasmic sperm injection (ICSI) failures with ejaculated spermatozoa. We compared the aneuploidy rate and quality between embryos derived from ICSI cycles with ejaculated sperm (EJ-ICSI) and those from ICSI cycles using testicular spermatozoa (TT-ICSI) within the same couple.

METHODS

Retrospective study of 27 couples who first underwent an EJ-ICSI cycle that did not result in a livebirth and afterwards a TT-ICSI cycle. Only the two closer cycles of each couple were included. Preimplantation genetic test for aneuploidies (PGT-A) was performed in both ICSI cycles and classic parameters of embryo quality were assessed until blastocyst-stage.

RESULTS

A total of 375 embryos from 54 ICSI cycles were evaluated. Aneuploidy rate was measured by two different parameters. Patients undergoing TT-ICSI presented a similar aneuploidy rate as EJ-ICSI group: 30.7% (23.4-38.0) vs 26.8% (18.1-35.5) per inseminated oocytes (P>0.05), and 76.2% (66.2-86.2) vs 72.1% (59.1-85.2) per the total number of biopsied embryos (P>0.05), respectively. Further, the good-quality blastocyst rate per correctly fertilized oocyte was significantly higher in TT-ICSI group (33.6% (30.4-36.9)) than EJ-ICSI group (24.2% (20.3-28.0)) (P<0.001).

CONCLUSIONS

Switching to testicular sperm for ICSI yielded better-quality blastocysts without affecting the chromosomal load of the embryos in non-azoospermic couples with a previous unsuccessful ICSI using ejaculated sperm. This strategy is a good option for couples seeking a livebirth who do not want to use donor sperm.

The relevance of sperm morphology in male infertility

This brief report concerns the role of human sperm morphology assessment in different fields of male infertility: basic research, genetics, assisted reproduction technologies, oxidative stress. One of the best methods in studying sperm morphology is transmission electron microscopy (TEM) that enables defining the concept of sperm pathology and classifying alterations in non-systematic and systematic. Non-systematic sperm defects affect head and tail in variable ratio, whereas the rare systematic defects are characterized by a particular anomaly that marks most sperm of an ejaculate. TEM analysis and fluorescence in situ hybridization represent outstanding methods in the study of sperm morphology and cytogenetic in patients with altered karyotype characterizing their semen quality before intracytoplasmic sperm injection. In recent years, the genetic investigations on systematic sperm defects, made extraordinary progress identifying candidate genes whose mutations induce morphological sperm anomalies. The question if sperm morphology has an impact on assisted fertilization outcome is debated. Nowadays, oxidative stress represents one of the most important causes of altered sperm morphology and function and can be analyzed from two points of view: 1) spermatozoa with cytoplasmic residue produce reactive oxygen species, 2) the pathologies with inflammatory/oxidative stress background cause morphological alterations. Finally, sperm morphology is also considered an important endpoint in in vitro experiments where toxic substances, drugs, antioxidants are tested. We think that the field of sperm morphology is far from being exhausted and needs other research. This parameter can be still considered a valuable indicator of sperm dysfunction both in basic and clinical research.

Single cell analysis of DNA in more than 10,000 individual sperm from men with abnormal reproductive outcomes

PURPOSE

This pilot study sought to (1) validate the use of a novel technology for single-sperm-cell genome sequencing (Sperm-seq) in infertile men who may not have optimal quantity or quality of sperm for genomic analysis and (2) compare these results to fertile donors.

METHODS

Infertile men undergoing IVF with female partners with a previous history of failed fertilization with ICSI (FF) or poor blastulation of embryos (PB) were recruited from a large IVF center. Sperm-seq was used to analyze thousands of individual sperm and was carried out at an affiliated university research institute. Global aneuploidy rate, crossover locations, and crossover frequencies were assessed in the infertile population, and compared with a control group of 20 fertile donors, which were analyzed previously at the same laboratory.

RESULTS

Eight patients were initially included, but 3 samples did not yield high-quality genomic data for analysis. A total of 10,042 sperm were analyzed from 5 patients, 2 in the FF group, and 3 in the PB group. The global aneuploidy rate among the samples was 2-4%, similar to the control group. Likewise, crossover locations and frequencies were similar.

CONCLUSION

Sperm-seq provides a robust analysis but may not be applicable to all male infertility cases due to technical limitations. This group of male infertility patients did not have higher rates of aneuploidy or abnormal crossover patterns compared to a fertile donor population. Our data may suggest that FF and PB phenotypes may not be related to sperm aneuploidy or meiotic errors but rather to other intrinsic nuclear anomalies.

Application of the FISH Technique to Visualize Sex Chromosomes in Domestic Cat Spermatozoa

Fluorescence in situ hybridization is a molecular cytogenetics technique that enables the visualization of chromosomes in cells via fluorescently labeled molecular probes specific to selected chromosomes. Despite difficulties in carrying out the FISH technique on sperm, related to the need for proper nuclear chromatin decondensation, this technique has already been used to visualize chromosomes in human, mouse, cattle, swine, horse, and dog spermatozoa. Until now, FISH has not been performed on domestic cat sperm; therefore, the aim of this study was to visualize sex chromosomes in domestic cat sperm. The results showed the presence of X and Y chromosomes in feline spermatozoa. The procedure used for sperm decondensation and fluorescence in situ hybridization was adequate to visualize chromosomes in domestic cat spermatozoa and, in the future, it may be used to determine the degree of chromosomal abnormalities in these gametes.

Methylenetetrahydrofolate reductase gene polymorphisms are not associated with embryo chromosomal abnormalities and IVF outcomes

The aim of our study was to investigate the effect of maternal and embryo MTHFR C677T and A1298C polymorphisms on embryo aneuploidies and mosaicism and the correlation between these genetic variants in transferred euploid embryos and IVF outcomes. MTHFR genotype was analyzed in 77 women who performed an IVF/ICSI cycle with PGT-A. Moreover, to evaluate the effect of embryo MTHFR polymorphisms on embryo aneuploidies and mosaicism, the MTHFR genotype was analyzed in 191 biopsied embryos from the PGT-A cycles of these patients. Additionally, 218 DNA samples from trophectoderm biopsies belonging to a different group of patients were also genotyped. MTHFR polymorphisms were analyzed in a total amount of 409 trophectoderm samples. The main parameters analyzed were embryo aneuploidy and mosaicism rates. Finally, the IVF outcomes of 241 single euploid embryo transfers were assessed and compared between different MTHFR embryo genotypes. The aneuploidy rates were similar in embryos from homozygous normal women and women with at least one mutated allele (54.7% vs. 30.2% in 677C>T and 37.8% vs. 42.7% in 1298A>C). Furthermore, no differences were observed in the mosaicism rate (24.0% vs. 13.8% in 677C>T and 17.1% vs. 17.3% in 1298A>C). A similar analysis was performed, taking into account the embryo genotype results. No differences in aneuploidy rate were observed between the study groups. The only significant difference was the mosaicism rate among 677C>T genotype (13.5% in 677CC group vs. 5.4% in 677CT/TT; p = 0.019). Implantation rate, biochemical and clinical miscarriage rates, and ongoing pregnancy rate were compared between different embryo genotypes, and no statistically significant differences were found. In conclusion, the maternal MTHFR genotype did not influence embryo chromosomal abnormalities. Moreover, the embryo MTHFR genotype was not associated with embryo aneuploidy or IVF outcomes such as implantation, pregnancy loss, and ongoing pregnancy when euploid embryos were transferred.Abbreviations: MTHFR: methylenetetrahydrofolate reductase; IVF: in vitro fertilization; PGT-A: preimplantation genetic testing for aneuploidies; SAM: S-adenosyl methionine; SNP: single nucleotide polymorphism; SPSS: Statistical Package for Social Sciences; RIF: recurrent implantation failure; RPL: recurrent pregnancy loss; hCG: human chorionic gonadotropin; PBS: phosphate buffered saline; CGH: comparative genomic hybridization; NGS: next generation sequencing.

Sperm nullisomy is not associated with routine semen parameters but it negatively impacts on ICSI outcomes

Sperm aneuploidy is a result of mis-segregation during meiosis and correlates with male infertility. Among the types of aneuploidy, nullisomy has been reported to be more prevalent in human spermatozoa than disomy; however, nullisomy is not always assessed by FISH, and its relation with basic semen parameters is almost unknown. To establish an association between nullisomy and semen parameters and pathologies, we evaluated the potential clinical value of semen analysis and assessed the diagnosis of sperm nullisomy. A prospective study including a total of 130 patients and 25 donors aged 30-50 years with a normal karyotype was carried out. Sperm FISH analyses were performed, and basic semen parameters and ART outcome data were collected. There were no associations between sperm nullisomy of chromosomes 13, 15, 18, 21, 22, X and Y and basic semen parameters. The odds of nullisomy of chromosomes 13, 15, 16, 17, 18, 21, 22, X and Y were not related to semen pathologies. However, sperm nullisomy had a negative impact on ART outcomes, with significant decreases in fertilisation, blastocyst, pregnancy and implantation rates after ICSI. Sperm nullisomy diagnoses are not detected in semen analyses and are a possible cause of idiopathic male infertility and unexplained recurrent pregnancy loss.

Centriolar defects, centrin 1 alterations, and FISH studies in human spermatozoa of a male partner of a couple that produces aneuploid embryos in natural and artificial fertilization

PURPOSE

To study the potential paternal contribution to aneuploidies in the man of a couple who obtained trisomic embryos with natural and assisted fertilization.

METHODS

Semen analysis, immunofluorescence for localization of tubulin and centrin 1, transmission electron microscopy (TEM), and fluorescence in situ hybridization (FISH) analysis for chromosomes 18 and 9 were performed. Sperm of fertile men were used as controls.

RESULTS

The percentages of sperm motility and normal forms were decreased. The percentages of sperm with tail reduced in dimension, headless tails, coiled tails, and altered head-tail junction were significantly higher (P < 0.01) in the patient than in controls, whereas the percentage of sperm with a normal centrin 1 localization (two spots in the centriolar area) was significantly reduced (P < 0.01) in the patient. Immunofluorescence with anti-tubulin antibody showed that in most of the patient's sperm connecting pieces (83.00 ± 1.78%), two spots were present, indicating prominent proximal centriole/centriolar adjunct and evident distal centriole, whereas controls' sperm displayed a single spot, indicating the proximal centriole. The percentage of sperm with two spots was significantly higher (P < 0.01) in the patient than in controls. TEM analysis showed that centriolar adjuncts of the patient's sperm were significantly longer (721.80 ± 122.26 nm) than in controls' sperm (310.00 ± 64.11 nm; P < 0.001). The aneuploidy frequencies of the patient's sperm, detected by FISH analysis, were increased with respect to controls.

CONCLUSION

A paternal contribution to sperm aneuploidies cannot be excluded since the patient's sperm showed altered morphology, immature centriolar adjunct, presence of evident distal centriole, scarce presence of centrin 1, and high aneuploidy frequency.

Frequency of Sperm Aneuploidy in Oligoasthenoteratozoospermic (OAT) Patients by Comprehensive Chromosome Screening: A Proof of Concept

Background:

Embryonic aneuploidy usually results in implantation failure and miscarriage. Considering significantly high frequency of sperm aneuploidy reported in oligoasthenoteratozoospermia (OAT) using fluorescence in situ hybridization (FISH) in limited number of chromosomes and lack of comprehensive chromosome screening (CCS) in OAT, the aim of this study was applying CCS in OAT sperm and comparison of the results with FISH findings.

Methods:

Five OAT patients with normal blood karyotypes and history of implantation failure were included. The successfully amplified samples, each containing two sperm, were analyzed by array comparative genomic hybridization (aCGH). FISH was utilized mainly depending on the aneuploidies found by aCGH to assess their frequencies in total sperm population.

Results:

In aCGH for 30 sperm, aneuploidy was found in 66% of samples. Following the study of 4300 sperm by FISH, an average of 55.46% aneuploidy was observed. No pregnancy was resulted with normal partners.

Conclusion:

Using aCGH, some abnormalities were observed that are not typically considered in sperm FISH studies. Despite small sample size of the comprehensive study, like other similar studies, the frequency of aneuploidies was considerable and similar to FISH. Aneuploidies revealed by aCGH at single sperm resolution were different from sperm population detected by FISH. Considering high frequency of aneuploidy in OATs sperm, preimplantation genetic testing for aneuploidy (PGT-A) can be used for in transfer of chromosomally normal embryos.

Advanced sperm testing

PURPOSE OF REVIEW

The sensitivity of semen analysis for detection of infertility remains low. Many factors not measured in traditional semen analysis may contribute to male factor infertility. DNA fragmentation, oxidative stress, and sperm aneuploidy are three factors that may contribute further information to the evaluation when semen analysis is inconclusive.

RECENT FINDINGS

DNA fragmentation measures the destruction of and failure to repair damage to DNA. Increased DNA fragmentation has been used as a marker for oxidative stress as well as toxic exposure. The oxidative stress adduct measures DNA aberrations, which sperm cannot repair and has been used to support use of antioxidants. Lastly, the aneuploid sperm frequency is a quantitative measure of deviation from the normal chromosomal complement. Although elevated sperm aneuploid frequency has been associated with recurrent pregnancy loss and implantation failures, barriers remain to its routine use.

SUMMARY

We identified these three adjunctive tests, which have the potential to alter either management or counseling of patients with regards to male factor infertility. Elevated DNA fragmentation or significant sperm aneuploidy may suggest the need for further investigation or further preimplantation genetic testing prior to IVF. The oxidative stress adduct may lend further explanation and improved counseling of the infertile patient.

Sperm genetic abnormalities and their contribution to embryo aneuploidy & miscarriage

Sperm genetic testing has been proposed for clinical diagnosis of possible causes of male infertility. We reviewed the most remarkable publications of sperm DNA integrity and sperm aneuploidy as they relate to clinical outcomes, and the relationship between both genetic defects, and its association to embryo aneuploidy and recurrent pregnancy loss.

Sperm chromosome abnormalities in patients with normal karyotype and in translocation carriers: clinical relevance for assisted reproductive technology

RESEARCH QUESTION

What is the proportion of chromosomally abnormal spermatozoa in men with a history of reproductive failure, including patients with normal karyotype and carriers of translocations? Should this analysis be included in a clinical setting to define the best treatment options for infertile couples?

DESIGN

Aneuploidy for chromosomes XY, 13, 15, 16, 17, 18, 21, 22 was tested by fluorescent in-situ hybridization (FISH) in 1665 samples from couples with normal karyotype having had at least three previous IVF failures, miscarriages, or both (group-A). A FISH test was also carried out in 76 samples from carriers of translocations (group B) to detect the proportion of spermatozoa with unbalanced rearrangement.

RESULTS

In group A, the lowest incidence of aneuploid sperm cells was found in men with normozoospermia (1.3%, range 0.09-6.31%) compared with men with moderate oligoasthenoteratozoospermia (2.1%, range 0.41-16.6%, P < 0.001), severe oligoasthenoteratozoospermia (4.7%, range 0.53-30.77, P < 0.001), microepididymal sperm aspiration (3.1%, range 1.19-24.24, P < 0.001) and testicular sperm extraction samples (5.8%, range 1.54-33.3, P < 0.001). In group B, the proportion of spermatozoa with unbalanced rearrangement was significantly higher in reciprocal (63%, range 10.0-87.6%) than in Robertsonian translocations (16%, range 4.3-51.0%, P < 0.001).

CONCLUSIONS

Patients with poor prognosis of term pregnancy tend to generate high proportions of chromosomally abnormal spermatozoa, especially in severe male factor cases. Corresponding frequencies occur at wide ranges; therefore, the FISH test is needed to assess the proportion of spermatozoa with altered chromosome condition. A flowchart, which included the FISH test, was designed to assist clinicians guide couples with poor prognosis of pregnancy, on the most indicated treatment options.

Characteristics of the IVF Cycle that Contribute to the Incidence of Mosaicism

Highly sensitive next-generation sequencing (NGS) platforms applied to preimplantation genetic testing for aneuploidy (PGT-A) allow the classification of mosaicism in trophectoderm biopsies. However, the incidence of mosaicism reported by these tests can be affected by a wide number of analytical, biological, and clinical factors. With the use of a proprietary algorithm for automated diagnosis of aneuploidy and mosaicism, we retrospectively analyzed a large series of 115,368 trophectoderm biopsies from 27,436 PGT-A cycles to determine whether certain biological factors and in vitro fertilization (IVF) practices influence the incidence of overall aneuploidy, whole uniform aneuploidy, mosaicism, and TE biopsies with only segmental aneuploidy. Older female and male patients showed higher rates of high-mosaic degree and whole uniform aneuploidies and severe oligozoospermic patients had higher rates of mosaicism and only segmental aneuploidies. Logistic regression analysis identified a positive effect of female age but a negative effect of embryo vitrification on the incidence of overall aneuploid embryos. Female age increased whole uniform aneuploidy rates but decreased only segmental aneuploidy and mosaicism, mainly low-mosaics. Conversely, higher ovarian response decreased whole uniform aneuploidy rates but increased only segmental aneuploidies. Finally, embryo vitrification decreased whole uniform aneuploidy rates but increased mosaicism, mainly low-mosaics, compared to PGT-A cycles with fresh oocytes. These results could be useful for clinician’s management of the IVF cycles.

Elimination of stress factors by continuous embryo culture and its influence on in vitro fertilization outcomes

Recently, infertility has become one of the most important endemic conditions, affecting approximately 15-20 % of couples worldwide. Among others, the careerist lifestyle, the increasing maternal age and the parallel increment in the aneuploidy rate of embryos play a crucial role in this phenomenon. In this study, embryological parameters and pregnancy outcomes were investigated in IVF cycles using either sequential embryo culture or a single step culture system. By sequential media, oocytes/embryos are needlessly exposed to the potentially negative effects of light exposure, temperature decrement and altered oxygen tension. In comparison with sequential media, single step media induced 1.28, 1.21 and 1.21-fold increments in implantation, biochemical pregnancy and clinical pregnancy rates, respectively. Pregnancy outcomes showed strong maternal age-dependency, so the difference between the two investigated culture systems was equalized by the increasing maternal ages (35-44 years) and the supposed incidence of embryo aneuploidy. Nevertheless, the significant enlargements in the outcomes of the younger ages (25-34) induced by the single step cultures suggest that, beside the resultant maternal aneuploidy, aneuploidy (reduced pregnancy rates) may evolve from exposure to the mentioned environmental stress factors.

Combined Preimplantation Genetic Testing for Autosomal Dominant Polycystic Kidney Disease: Consequences for Embryos Available for Transfer

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease and presents with genetic and clinical heterogeneity. ADPKD can also manifest extra-renally, and seminal cysts have been associated with male infertility in some cases. ADPKD-linked male infertility, along with female age, have been proposed as factors that may influence the clinical outcomes of preimplantation genetic testing (PGT) for monogenic disorders (PGT-M). Large PGT for aneuploidy assessment (PGT-A) studies link embryo aneuploidy to increasing female age; other studies suggest that embryo aneuploidy is also linked to severe male-factor infertility. We aimed to assess the number of aneuploid embryos and the number of cycles with transferable embryos in ADPKD patients after combined-PGT. The combined-PGT protocol, involving PGT-M by PCR and PGT-A by next-generation sequencing, was performed in single trophectoderm biopsies from 289 embryos in 83 PGT cycles. Transferable embryos were obtained in 69.9% of cycles. The number of aneuploid embryos and cycles with transferable embryos did not differ when the male or female had the ADPKD mutation. However, a significantly higher proportion of aneuploid embryos was found in the advanced maternal age (AMA) group, but not in the male factor (MF) group, when compared to non-AMA and non-MF groups, respectively. Additionally, no significant differences in the percentage of cycles with transferable embryos were found in any of the groups. Our results indicate that AMA couples among ADPKD patients have an increased risk of aneuploid embryos, but ADPKD-linked male infertility does not promote an increased aneuploidy rate.