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Mitochondria are essential organelles with specialized functions, which play crucial roles in energy production, calcium homeostasis, and programmed cell death. In oocytes, mitochondrial populations are inherited maternally and are vital for developmental competence. Dysfunction in mitochondrial quality control mechanisms can lead to reproductive failure. Due to their central role in oocyte and embryo development, mitochondria have been investigated as potential diagnostic and therapeutic targets in assisted reproduction. Pharmacological agents that target mitochondrial function and show promise in improving assisted reproduction outcomes include antioxidant coenzyme Q10 and mitoquinone, mammalian target of rapamycin signaling pathway inhibitor rapamycin, and nicotinamide mononucleotide. Mitochondrial replacement therapies (MRTs) offer solutions for infertility and mitochondrial disorders. Autologous germline mitochondrial energy transfer initially showed promise but failed to demonstrate significant benefits in clinical trials. Maternal spindle transfer (MST) and pronuclear transfer hold potential for preventing mitochondrial disease transmission and improving oocyte quality. Clinical trials of MST have shown promising outcomes, but larger studies are needed to confirm safety and efficacy. However, ethical and legislative challenges complicate the widespread implementation of MRTs.
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Mitochondria are commonly recognized as the powerhouses of the cell, primarily responsible for energy production through oxidative phosphorylation. Alongside this vital function, they also play crucial roles in regulating calcium signaling, maintaining membrane potential, and modulating apoptosis. Their involvement in various cellular pathways becomes particularly evident during oogenesis and embryogenesis, where mitochondrial quantity, morphology, and distribution are tightly controlled. The efficiency of the mitochondrial network is maintained through multiple quality control mechanisms that are essential for reproductive success. These include mitochondrial unfolded protein response, mitochondrial dynamics, and mitophagy. Not surprisingly, mitochondrial dysfunction has been implicated in infertility and ovarian aging, prompting investigation into mitochondria as diagnostic and therapeutic targets in assisted reproduction. To date, mitochondrial DNA copy number in oocytes, cumulus cells, and trophectoderm biopsies, and fluorescent lifetime imaging microscopy-based assessment of NADH and flavin adenine dinucleotide content have been explored as potential predictors of embryo competence, yielding limited success. Despite challenges in the clinical application of mitochondrial diagnostic strategies, these enigmatic organelles have a significant impact on reproduction, and their potential role as diagnostic targets in assisted reproduction is likely to remain an active area of investigation in the foreseeable future.
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Recent advances in preimplantation genetic testing for aneuploidy (PGT-A) have significantly enhanced its application in ART, providing critical insights into embryo viability, and potentially reducing both the time spent in fertility treatments and the risk of pregnancy loss. With the integration of next-generation sequencing, PGT-A now offers greater diagnostic precision, although challenges related to segmental aneuploidies and mosaicism remain. The emergence of non-invasive PGT-A (niPGT-A), which analyzes DNA in spent embryo culture media, promises a simpler aneuploidy screening method. This mini review assesses the methodological criteria for test validation, the current landscape of PGT-A, and the potential of niPGT-A, while evaluating its advantages and potential pitfalls. It underscores the importance of a robust three-phase validation process to ensure the clinical reliability of PGT-A. Despite initial encouraging data, niPGT-A not only confronts issues of DNA amplification failure and diagnostic inaccuracies but also has yet to meet the three-prong criteria required for appropriate test validation, necessitating further research for its clinical adoption. The review underscores that niPGT-A, like traditional PGT-A, must attain the high standards of precision and reliability expected of any genetic testing platform used in clinical settings before it can be adopted into routine ART protocols.
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PURPOSE: Investigate patient preferences in embryo selection for transfer regarding quality versus sex in IVF/ICSI cycles with PGT-A and assess associated clinical implications. METHODS: Retrospective cohort study at a university fertility practice from January 2012 to December 2021. Included were patients undergoing single frozen euploid transfers with at least one embryo of each sex available. Primary outcomes were preference for embryo selection (quality vs. sex) and sex preference (male vs. female). Trends over 10 years were evaluated and clinical outcomes, including clinical pregnancy rate (CPR), sustained implantation rate (SIR), and live birth rate (LBR), were compared. RESULTS: A total of 5,145 embryo transfer cycles were included; 54.5% chose the best-quality embryo, while 45.5% selected based on sex. Among those choosing based on sex, 56.5% chose male embryos and 43.5% chose female. Preference for quality remained consistent over the decade (p = 0.30), while male embryos were consistently favored (p = 0.64). Best-quality embryos had higher grades (p < 0.001). Clinical outcomes were similar between groups (CPR: 74.4% vs. 71.9%, p = 0.05; SIR: 64.9% vs. 63.4%, p = 0.26; LBR: 58.8% vs. 56.7%, p = 0.13), and between male and female embryo selections. CONCLUSIONS: Sex selection remains common, with 45.5% selecting embryos based on sex, predominantly favoring males. This trend persisted over 10 years, with comparable clinical outcomes regardless of selection criteria.
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STUDY QUESTION: Does intraovarian platelet-rich plasma (PRP) injection increase the number of mature oocytes obtained after controlled ovarian stimulation (COS) in young women with poor ovarian response (POR) undergoing IVF? SUMMARY ANSWER: Intraovarian PRP injection procedure does not improve mature oocyte yield after COS in women less than 38 years old with an established IVF history of POR. WHAT IS KNOWN ALREADY: POR is frequently encountered among the infertile population and the number of women seeking infertility treatment related to POR is increasing. Effective treatment options for this patient population to conceive with autologous oocytes are lacking. Case series and cohort studies suggest that intraovarian PRP injection may improve follicular recruitment in women with premature ovarian insufficiency (POI) and POR, yet robust randomized studies have not been performed to date to determine the clinical utility of this intervention. STUDY DESIGN, SIZE, DURATION: This was a multi-center randomized controlled trial (RCT) conducted at university-affiliated reproductive centers in the USA and Turkey, between January 2020 and November 2022. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients who met inclusion criteria (<38 years old, two or more prior cycles with <3 oocytes retrieved; and without single gene disorders, prior ovarian surgery, endometriomas, BMI >35 kg/m2, or severe male factor infertility) were randomized to either the PRP or control group. Patients in both groups subsequently underwent COS, oocyte retrieval, ICSI, preimplantation genetic testing for aneuploidy (PGT-A), and single euploid embryo transfer. Number of metaphase II (MII) oocytes obtained was the primary outcome. Secondary outcomes included ovarian reserve tests (antral follicle count [AFC] and anti-Müllerian hormone [AMH]), blastocyst and euploid blastocyst yields, and sustained implantation. The study was powered to detect a difference of one mature oocyte obtained at oocyte retrieval. MAIN RESULTS AND THE ROLE OF CHANCE: In total, 83 patients met inclusion criteria and were randomized to receive autologous intraovarian PRP injection (n = 41) or to no intervention (n = 42). No significant differences were observed in number of MII oocytes retrieved per cycle (2.8 ± 2.4 vs 3.1 ± 3.3 in PRP vs control, respectively; P = 0.9), blastocysts (1.0 ± 1.3 vs 1.3 ± 2.1, P = 0.8), or euploid blastocysts (0.8 ± 1.1 vs 0.9 ± 1.6; P = 0.5). Similarly, no differences were observed in the likelihood of obtaining at least one euploid blastocyst (45% vs 37%, P = 0.4; relative risk [RR], 95% CI = 0.9, 0.6-1.2) or the rate of sustained implantation (31% vs 29%, P = 0.9; RR 1.0, 0.7-1.3). Posttreatment AFC (7.9 ± 4.5 vs 6.8 ± 4.8, P = 0.3) and AMH (0.99 ± 0.98 vs 0.7 ± 0.6, P = 0.2) were also not different between the groups. LIMITATIONS, REASONS FOR CAUTION: Results from this RCT may not be generalizable to other PRP preparations owing to heterogeneity and lack of standardization. The control groups did not undergo a sham ovarian injection, which would have been relevant had the results shown benefit of PRP injection. Only patients with POR were included in this study, and these results may not be generalizable to more severe diminution of ovarian reserve, as seen with POI. WIDER IMPLICATIONS OF THE FINDINGS: The intraovarian PRP injection procedure does not improve mature oocyte yield or other parameters of IVF outcome in women less than 38 years old with an established IVF history of POR. The results from this study do not support the use of intraovarian PRP injection in this population. STUDY FUNDING/COMPETING INTEREST(S): Departmental funds were used and no external funding was requested for this study. ES is a consultant for and receives grant funding from the Foundation for Embryonic Competence. All other authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov Registry Identifier: NCT04163640. TRIAL REGISTRATION DATE: 15 November 2019. DATE OF FIRST PATIENT'S ENROLMENT: 24 February 2020.
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BACKGROUND: The establishment and maintenance of pregnancy depend on endometrial competence. Asherman syndrome (AS) and intrauterine adhesions (IUA), or endometrial atrophy (EA) and thin endometrium (TE), can either originate autonomously or arise as a result from conditions (i.e. endometritis or congenital hypoplasia), or medical interventions (e.g. surgeries, hormonal therapies, uterine curettage or radiotherapy). Affected patients may present an altered or inadequate endometrial lining that hinders embryo implantation and increases the risk of poor pregnancy outcomes and miscarriage. In humans, AS/IUA and EA/TE are mainly treated with surgeries or pharmacotherapy, however the reported efficacy of these therapeutic approaches remains unclear. Thus, novel regenerative techniques utilizing stem cells, growth factors, or tissue engineering have emerged to improve reproductive outcomes. OBJECTIVE AND RATIONALE: This review comprehensively summarizes the methodologies and outcomes of emerging biotechnologies (cellular, acellular, and bioengineering approaches) to treat human endometrial pathologies. Regenerative therapies derived from human tissues or blood which were studied in preclinical models (in vitro and in vivo) and clinical trials are discussed. SEARCH METHODS: A systematic search of full-text articles available in PubMed and Embase was conducted to identify original peer-reviewed studies published in English between January 2000 and September 2023. The search terms included: human, uterus, endometrium, Asherman syndrome, intrauterine adhesions, endometrial atrophy, thin endometrium, endometritis, congenital hypoplasia, curettage, radiotherapy, regenerative therapy, bioengineering, stem cells, vesicles, platelet-rich plasma, biomaterials, microfluidic, bioprinting, organoids, hydrogel, scaffold, sheet, miRNA, sildenafil, nitroglycerine, aspirin, growth hormone, progesterone, and estrogen. Preclinical and clinical studies on cellular, acellular, and bioengineering strategies to repair or regenerate the human endometrium were included. Additional studies were identified through manual searches. OUTCOMES: From a total of 4366 records identified, 164 studies (3.8%) were included for systematic review. Due to heterogeneity in the study design and measured outcome parameters in both preclinical and clinical studies, the findings were evaluated qualitatively and quantitatively without meta-analysis. Groups using stem cell-based treatments for endometrial pathologies commonly employed mesenchymal stem cells (MSCs) derived from the human bone marrow or umbilical cord. Alternatively, acellular therapies based on platelet-rich plasma (PRP) or extracellular vesicles are gaining popularity. These are accompanied by the emergence of bioengineering strategies based on extracellular matrix (ECM)-derived hydrogels or synthetic biosimilars that sustain local delivery of cells and growth factors, reporting promising results. Combined therapies that target multiple aspects of tissue repair and regeneration remain in preclinical testing but have shown translational value. This review highlights the myriad of therapeutic material sources, administration methods, and carriers that have been tested. WIDER IMPLICATIONS: Therapies that promote endometrial proliferation, vascular development, and tissue repair may help restore endometrial function and, ultimately, fertility. Based on the existing evidence, cost, accessibility, and availability of the therapies, we propose the development of triple-hit regenerative strategies, potentially combining high-yield MSCs (e.g. from bone marrow or umbilical cord) with acellular treatments (PRP), possibly integrated in ECM hydrogels. Advances in biotechnologies together with insights from preclinical models will pave the way for developing personalized treatment regimens for patients with infertility-causing endometrial disorders such as AS/IUA, EA/TE, and endometritis. REGISTRATION NUMBER: https://osf.io/th8yf/.
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PURPOSE OF REVIEW: Poor ovarian response (POR) remains a key challenge to the success of assisted reproductive technology. Here, we offer a comprehensive review of the two main classification systems for POR, discussing their promises and pitfalls, evaluating their performance, and exploring potential avenues for improving upon these definitions of POR. RECENT FINDINGS: The Bologna criteria represented the first meaningful attempt to create a universal POR definition. Subsequently, the POSEIDON classification system was published to provide a more nuanced view of POR, classifying patients into four groups based on age and ovarian reserve markers. A recent study evaluated the likelihood of achieving at least one euploid embryo for transfer and found that, indeed, these classification systems are effective predictors of this outcome.While these criteria provide an effective counseling tool, several limitations - not considering underlying conditions, selecting somewhat arbitrary cutoffs, and evaluating the number of oocytes retrieved regardless of maturity - highlight the importance of improving upon these systems to create a more useful tool to more accurately predict ovarian response for clinical and research purposes. SUMMARY: In the era of personalized medicine, it is time to reconsider whether diagnostic criteria for a continuous metric such as ovarian response should be based on meeting all-or-nothing thresholds for specific parameters.
Subject(s)
Ovarian Reserve , Ovulation Induction , Humans , Female , Ovarian Reserve/physiology , Ovulation Induction/methods , Pregnancy , Ovary , Infertility, Female/classification , Infertility, Female/therapy , Embryo Transfer , Oocyte Retrieval , Fertilization in Vitro/methods , Reproductive Techniques, AssistedABSTRACT
PURPOSE: To investigate whether leukocytospermia (defined as the presence of ≥ 1 × 106 white blood cells/mL) affects clinical and embryologic outcomes in in vitro fertilization (IVF) cycles with intracytoplasmic sperm injection (ICSI) and preimplantation genetic testing for aneuploidy (PGT-A). METHODS: This was a retrospective cohort study including 5425 cycles between January 2012 to December 2021 at a single large university-affiliated fertility clinic. The primary outcome was live birth rate (LBR). RESULTS: The prevalence of leukocytospermia was 33.9% (n = 1843). Baseline characteristics including female age, BMI, AMH, Day 3 FSH, and male partner's age were similar in cycles with and without leukocytospermia. The LBR after the first euploid embryo transfer was similar in those with and without leukocytospermia (62.3% vs. 63% p = 0.625). Secondary outcomes including clinical pregnancy rate (CPR), sustained implantation rate (SIR), fertilization (2PN) rate, blastulation rate, and aneuploidy rate were also evaluated. The CPR (73.3% vs 74.9%, p = 0.213) and SIR (64.6% vs. 66%, p = 0.305) were similar in both groups. The 2PN rate was also similar in both groups (85.7% vs. 85.8%, p = 0.791), as was the blastulation rate per 2PN (56.7% vs. 57.5%, p = 0.116). The aneuploidy rate was not significantly different between groups (25.7% vs 24.4%, p = 0.053). A generalized estimation equation with logistic regression demonstrated that the presence leukocytospermia did not influence the LBR (adjusted OR 0.878; 95% CI, 0.680-1.138). CONCLUSION: Leukocytospermia diagnosed just prior to an IVF cycle with PGT-A does not negatively impact clinical or embryologic outcomes.
Subject(s)
Aneuploidy , Embryo Transfer , Fertilization in Vitro , Genetic Testing , Pregnancy Rate , Preimplantation Diagnosis , Sperm Injections, Intracytoplasmic , Humans , Female , Sperm Injections, Intracytoplasmic/methods , Pregnancy , Male , Adult , Embryo Transfer/methods , Retrospective Studies , Live Birth/epidemiology , Live Birth/genetics , Birth Rate , Leukocytes/pathology , Infertility, Male/genetics , Infertility, Male/pathology , Infertility, Male/therapy , Infertility, Male/diagnosis , Embryo Implantation/geneticsABSTRACT
STUDY QUESTION: What are the clinical pregnancy and live birth rates in women who underwent up to two more euploid blastocyst transfers after three failures in the absence of another known factor that affects implantation? SUMMARY ANSWER: The fourth and fifth euploid blastocyst transfers resulted in similar live birth rates of 40% and 53.3%, respectively, culminating in a cumulative live birth rate of 98.1% (95% CI = 96.5-99.6%) after five euploid blastocyst transfers. WHAT IS KNOWN ALREADY: The first three euploid blastocysts have similar implantation and live birth rates and provide a cumulative live birth rate of 92.6%. STUDY DESIGN, SIZE, DURATION: An international multi-center retrospective study was conducted at 25 individual clinics. The study period spanned between January 2012 and December 2022. A total of 123 987 patients with a total of 64 572 euploid blastocyst transfers were screened for inclusion. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients with a history of any embryo transfer at another clinic, history of any unscreened embryo transfer at participating clinics, parental karyotype abnormalities, the use of donor oocytes or a gestational carrier, untreated intracavitary uterine pathology (e.g. polyp, leiomyoma), congenital uterine anomalies, adenomyosis, communicating hydrosalpinx, endometrial thickness <6 mm prior to initiating of progesterone, use of testicular sperm due to non-obstructive azoospermia in the male partner, transfer of an embryo with a reported intermediate chromosome copy number (i.e. mosaic), preimplantation genetic testing cycles for monogenic disorders, or structural chromosome rearrangements were excluded. Ovarian stimulation protocols and embryology laboratory procedures including trophectoderm biopsy followed the usual practice of each center. The ploidy status of blastocysts was determined with comprehensive chromosome screening. Endometrial preparation protocols followed the usual practice of participating centers and included programmed cycles, natural or modified natural cycles. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 105 (0.085% of the total population) patients met the criteria and underwent at least one additional euploid blastocyst transfer after failing to achieve a positive pregnancy test with three consecutive euploid blastocyst transfers. Outcomes of the fourth and fifth euploid blastocyst transfers were similar across participating centers. Overall, the live birth rate was similar with the fourth and fifth euploid blastocysts (40% vs 53.3%, relative risk = 1.33, 95% CI = 0.93-1.9, P value = 0.14). Sensitivity analyses excluding blastocysts biopsied on Day 7 postfertilization, women with a BMI >30 kg/m2, cycles using non-ejaculate or donor sperm, double-embryo transfer cycles, and cycles in which the day of embryo transfer was modified due to endometrial receptivity assay test result yielded similar results. Where data were available, the fourth euploid blastocyst had similar live birth rate with the first one (relative risk = 0.84, 95% CI = 0.58-1.21, P = 0.29). The cumulative live birth rate after five euploid blastocyst transfers was 98.1% (95% CI = 96.5-99.6%). LIMITATIONS, REASONS FOR CAUTION: Retrospective design has its own inherent limitations. Patients continuing with a further euploid embryo transfer and patients dropping out from treatment after three failed euploid transfers can be systematically different, perhaps with regard to ovarian reserve or economic status. WIDER IMPLICATION OF THE FINDINGS: Implantation failure seems to be mainly due to embryonic factors. Given the stable and high live birth rates up to five euploid blastocysts, unexplained recurrent implantation failure should have a prevalence of <2%. Proceeding with another embryo transfer can be the best next step once a known etiology for implantation failure is ruled out. STUDY FUNDING/COMPETING INTEREST(S): None. TRIAL REGISTRATION NUMBER: N/A.
Subject(s)
Embryo Implantation , Embryo Transfer , Pregnancy Rate , Humans , Female , Pregnancy , Retrospective Studies , Embryo Transfer/methods , Embryo Transfer/statistics & numerical data , Adult , Prevalence , Birth Rate , Live Birth , Treatment Failure , Blastocyst , Fertilization in Vitro/methods , Fertilization in Vitro/statistics & numerical data , Pregnancy Outcome/epidemiologyABSTRACT
Caseinolytic peptidase P (CLPP) plays a central role in mitochondrial unfolded protein response (mtUPR) by promoting the breakdown of misfolded proteins and setting in motion a cascade of reactions to re-establish protein homeostasis. Global germline deletion of Clpp in mice results in female infertility and accelerated follicular depletion. Telomeres are tandem repeats of 5'-TTAGGG-3' sequences found at the ends of the chromosomes. Telomeres are essential for maintaining chromosome stability during somatic cell division and their shortening is associated with cellular senescence and aging. In this study, we asked whether the infertility and ovarian aging phenotype caused by global germline deletion of Clpp is associated with somatic aging, and tested telomere length in tissues of young and aging mice. We found that impaired mtUPR caused by the lack of CLPP is associated with accelerated telomere shortening in both oocytes and somatic cells of aging mice. In addition, expression of several genes that maintain telomere integrity was decreased, and double-strand DNA breaks were increased in telomeric regions. Our results highlight how impaired mtUPR can affect telomere integrity and demonstrate a link between loss of mitochondrial protein hemostasis, infertility, and somatic aging.
Subject(s)
Infertility, Female , Telomerase , Humans , Female , Animals , Mice , Telomere Shortening , Oocytes/metabolism , Aging/genetics , Telomere/genetics , Telomere/metabolism , Infertility, Female/metabolism , Unfolded Protein Response/genetics , Telomerase/metabolismABSTRACT
Mitochondrial dysfunction is widely implicated in various human diseases, through mechanisms that go beyond mitochondria's well-established role in energy generation. These dynamic organelles exert vital control over numerous cellular processes, including calcium regulation, phospholipid synthesis, innate immunity, and apoptosis. While mitochondria's importance is acknowledged in all cell types, research has revealed the exceptionally dynamic nature of the mitochondrial network in oocytes and embryos, finely tuned to meet unique needs during gamete and pre-implantation embryo development. Within oocytes, both the quantity and morphology of mitochondria can significantly change during maturation and post-fertilization. These changes are orchestrated by fusion and fission processes (collectively known as mitochondrial dynamics), crucial for energy production, content exchange, and quality control as mitochondria adjust to the shifting energy demands of oocytes and embryos. The roles of proteins that regulate mitochondrial dynamics in reproductive processes have been primarily elucidated through targeted deletion studies in animal models. Notably, impaired mitochondrial dynamics have been linked to female reproductive health, affecting oocyte quality, fertilization, and embryo development. Dysfunctional mitochondria can lead to fertility problems and can have an impact on the success of pregnancy, particularly in older reproductive age women.
Subject(s)
Mitochondrial Dynamics , Oocytes , Pregnancy , Animals , Female , Humans , Aged , Mitochondria/metabolism , Embryonic Development , DNA, Mitochondrial/metabolismABSTRACT
Mitochondrial unfolded protein stress response (mtUPR) plays a critical role in regulating cellular and metabolic stress response and helps maintain protein homeostasis. Caseinolytic peptidase P (CLPP) is one of the key regulators of mtUPR and promotes unfolded protein degradation. Previous studies demonstrated that global deletion of Clpp resulted in female infertility, whereas no impairment was found in the mouse model with targeted deletion of Clpp in cumulus/granulosa cells. These results suggest the need to delineate the function of Clpp in oocytes. In this study, we aimed to further explore the role of mtUPR in female reproductive competence and senescence using a mouse model. Oocyte-specific targeted deletion of Clpp in mice resulted in female subfertility associated with metabolic and functional abnormalities in oocytes, thus highlighting the importance of CLPP-mediated protein homeostasis in oocyte competence and reproductive function.
Subject(s)
Endopeptidase Clp , Infertility, Female , Mitochondria , Female , Fertility/genetics , Infertility, Female/genetics , Infertility, Female/metabolism , Mitochondria/metabolism , Oocytes/metabolism , Unfolded Protein Response/genetics , Endopeptidase Clp/genetics , Endopeptidase Clp/metabolism , Animals , MiceABSTRACT
Both spontaneously conceived pregnancies and those achieved using assisted reproduction decline with advancing maternal age. In this study, we tested if rapamycin and/or cumulus cells (CCs) from young donors could improve oocyte maturation and euploidy rates of germinal vesicle (GV) stage oocytes obtained from older women of reproductive age. A total of 498 GVs from 201 women >38 years (40.6 ± 1.8, mean ± SD) were included. GVs were randomly assigned into five groups for rescue IVM: control (with no CCs and no rapamycin); with autologous CCs; with autologous CCs and rapamycin; with CCs from young women (<35 years); and with CCs from young women and rapamycin. After 24 h of culture, the first polar body (PB) was biopsied in metaphase II oocytes, and the cytogenetic constitution was assessed using next-generation sequencing for both oocytes and PBs. Comparable maturation rates were found (56.2%, 60.0%, 46.5%, 51.7%, and 48.5% for groups 1-5, respectively; P = 0.30). Similarly, comparable euploidy rates were observed in the five groups (41.5%, 37.8%, 47.2%, 43.6%, and 47.8% for Groups 1-5, respectively; P = 0.87). Our findings indicate that rescue IVM is effective for obtaining mature euploid oocytes in older women of reproductive age, and that incubation with rapamycin or CCs obtained from young donors does not improve the maturation or euploidy rate.
Subject(s)
Cumulus Cells , In Vitro Oocyte Maturation Techniques , Female , Humans , Pregnancy , Coculture Techniques , Oocytes , Oogenesis , Sirolimus/pharmacology , AdultABSTRACT
RESEARCH QUESTION: Does rescue in-vitro maturation (IVM) in the presence or absence of cumulus cells, affect the progress of meiosis I, compared with oocytes that mature in vivo? DESIGN: This prospective study was conducted in a university-affiliated fertility centre. Ninety-five young oocyte donors (mean age 25.57 ± 4.47) with a normal karyotype and no known fertility problems were included. A total of 390 oocytes (116 mature metaphase II [MII] and 274 immature oocytes) were analysed. The immature oocytes underwent rescue IVM in the presence of cumulus cells (CC; IVM+CC; nâ¯=â¯137) or without them (IVM-CC; nâ¯=â¯137), and IVM rate was calculated. Chromosome copy number analysis using next-generation sequencing (NGS) was performed on all rescue IVM oocytes reaching MII as well as those that were mature at the time of initial denudation (in-vivo-matured oocytes [IVO]). RESULTS: Maturation rates were similar in IVM+CC and IVM-CC oocytes (62.8 versus 71.5%, Pâ¯=â¯0.16). Conclusive cytogenetic results were obtained from 65 MII oocytes from the IVM+CC group, 87 from the IVM-CC group, and 99 from the IVO group. Oocyte euploidy rates for the three groups were similar, at 75.4%, 83.9% and 80.8%, respectively (Pâ¯=â¯0.42). CONCLUSIONS: The results suggest that culture of germinal vesicle and metaphase I oocytes in the presence of cumulus cells does not improve rates of IVM. In general, the process of rescue IVM does not appear to alter the frequency of oocytes with a normal chromosome copy number.
Subject(s)
Chromosome Segregation , In Vitro Oocyte Maturation Techniques , Humans , Young Adult , Adult , Prospective Studies , Oocytes , MeiosisABSTRACT
The average childbearing age among women continues to rise, leading to an increased prevalence of infertility and a subsequent increased use of assisted reproductive technologies (ARTs). Ovarian aging, especially diminished ovarian reserve and poor ovarian response, have been implicated as common causes of infertility. Telomere length and DNA methylation-based epigenetic clocks are established hallmarks of cellular aging; however, the interplay between somatic and ovarian aging remains unclear. There appears to be a lack of correlation between leukocyte telomere length and the DNA methylation age of somatic and ovarian cells. Both the telomere length and methylome of follicular somatic cells (granulosa and cumulus) appear to be unaffected by chronologic age, infertility, or processes that result in diminished ovarian reserve and poor ovarian response. As such, they are unlikely candidates as surrogate biomarkers of reproductive potential, response to stimulation, or ART outcome. Meanwhile, telomere or methylome changes in leukocytes associated with aging seem to correlate with reproductive function and may have the potential to aid the characterization of women with reproductive decline; however, current data are limited and larger studies evaluating this within an ART setting are warranted.
Subject(s)
Infertility, Female , Ovarian Reserve , Female , Humans , Ovarian Reserve/genetics , Epigenome , Aneuploidy , Leukocytes/physiology , Infertility, Female/diagnosis , Infertility, Female/genetics , Telomere/genetics , BiomarkersABSTRACT
Ovarian aging is the main cause of infertility and telomere attrition is common to both aging and fertility disorders. Senescence-Accelerated Mouse Prone 8 (SAMP8) model has shortened lifespan and premature infertility, reflecting signs of reproductive senescence described in middle-aged women. Thus, our objective was to study SAMP8 female fertility and the telomere pathway at the point of reproductive senescence. The lifespan of SAMP8 and control mice was monitored. Telomere length (TL) was measured by in situ hybridization in blood and ovary. Telomerase activity (TA) was analyzed by telomere-repeat amplification protocol, and telomerase expression, by real-time quantitative PCR in ovaries from 7-month-old SAMP8 and controls. Ovarian follicles at different stages of maturation were evaluated by immunohistochemistry. Reproductive outcomes were analyzed after ovarian stimulation. Unpaired t-test or Mann-Whitney test were used to calculate p-values, depending on the variable distribution. Long-rank test was used to compare survival curves and Fisher's exact test was used in contingency tables. Median lifespan of SAMP8 females was reduced compared to SAMP8 males (p = 0.0138) and control females (p < 0.0001). In blood, 7-month-old SAMP8 females presented lower mean TL compared to age-matched controls (p = 0.041). Accordingly, the accumulation of short telomeres was higher in 7-month-old SAMP8 females (p = 0.0202). Ovarian TA was lower in 7-month-old SAMP8 females compared to controls. Similarly, telomerase expression was lower in the ovaries of 7-month-old SAMP8 females (p = 0.04). Globally, mean TL in ovaries and granulosa cells (GCs) were similar. However, the percentage of long telomeres in ovaries (p = 0.004) and GCs (p = 0.004) from 7-month-old SAMP8 females was lower compared to controls. In early-antral and antral follicles, mean TL of SAMP8 GCs was lower than in age-matched controls (p = 0.0156 for early-antral and p = 0.0037 for antral follicles). Middle-aged SAMP8 showed similar numbers of follicles than controls, although recovered oocytes after ovarian stimulation were lower (p = 0.0068). Fertilization rate in oocytes from SAMP8 was not impaired, but SAMP8 mice produced significantly more morphologically abnormal embryos than controls (27.03% in SAMP8 vs. 1.22% in controls; p < 0.001). Our findings suggest telomere dysfunction in SAMP8 females, at the time of reproductive senescence.
Subject(s)
Infertility , Telomerase , Male , Female , Mice , Animals , Telomerase/genetics , Telomerase/metabolism , Aging/genetics , Fertility/physiology , Telomere/metabolismABSTRACT
OBJECTIVE: To study the likelihood of obtaining at least 1 euploid embryo for transfer in poor ovarian response (POR) diagnosed per Bologna and Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number (POSEIDON) criteria, and compare it between groups and with patients without POR. DESIGN: Retrospective cohort study. PATIENTS: Women undergoing an ovarian stimulation cycle with intention to pursue preimplantation genetic testing for aneuploidy. INTERVENTIONS: Bologna criteria and the POSEIDON classification system were applied to characterize each stimulation cycle as POR or not. Cycles identified as POR by POSEIDON were subdivided into groups I, II, III, and IV as defined by this classification system. MAIN OUTCOME MEASURES: The proportion of cycles resulting in at least 1 euploid blastocyst. Other outcome measures included cycle yields (metaphase II oocytes, fertilized oocytes, blastocysts, and euploid blastocysts), and euploidy rate per embryo cohort. RESULTS: A total of 6,889 cycles were included, of which 3,653 (53.0%) were classified as POR per POSEIDON criteria: 1.5% (100/6,889) in group I, 3.2% (222/6,889) in II, 11.9% (817/6,889) in III, and 36.5% (2,514/6,889) in IV. Per Bologna criteria, 23.4% (1,612/6,889) of cycles were classified as POR. Group I had similar likelihood of obtaining at least 1 euploid embryo (97.0%; 95% confidence interval, 91.5%-99.2%) as cycles not deemed POR (91.9%; 95% confidence interval, 90.9%-2.8%), whereas this decreased significantly with each subsequent POSEIDON group (II: 77.9%, 72.0%-82.9%; III: 70.5%, 67.3%-73.5%; IV: 44.8%, 42.9%-46.7%) and those meeting Bologna criteria had the lowest rates (31.9%, 29.7%-34.3%). Cycle yields correlated with ovarian reserve testing results, whereas euploidy rates were associated with age. CONCLUSIONS: Although younger POSEIDON groups (I and III) have higher euploidy rates than older groups (II and IV), each incremental POSEIDON group poses a higher risk of having no euploid blastocysts; with POSEIDON I being no different from non-POSEIDON, and Bologna having the worst prognosis. Although ovarian reserve appears to have little impact on euploidy rates, it remains a key prognostic factor for having at least 1 euploid embryo available for transfer through its impact on oocyte yield. To our knowledge, this is the first study to provide the odds ratio of this outcome depending on the degree of POR.
ABSTRACT
PURPOSE OF REVIEW: Embryonic arrest is a key determinant of the number of euploid blastocysts obtained after IVF. Here, we review factors that are implicated in the developmental arrest of preimplantation embryos and their relevance for assisted reproduction outcomes. RECENT FINDINGS: Among the treatment options available to infertile women, IVF is the one associated with most favorable outcomes. The cumulative pregnancy rates in women undergoing IVF are determined by aneuploidy rate (age), ovarian response to stimulation (ovarian reserve), and the rate of embryo developmental arrest. Mutations in maternal effect genes, especially those encoding for subcortical maternal complex, have been implicated in human embryo developmental arrest. In addition, perturbation of biological processes, such as mitochondrial unfolded protein response and long noncoding RNA regulatory pathways, may play a role. However, how each of these factors contributes to embryos' arrest in different cohorts and age groups has not been determined. SUMMARY: Arrest of human embryos during preimplantation development is a common occurrence and is partly responsible for the limited number of euploid blastocysts obtained in assisted reproduction cycles. Although genetic and metabolic causes have been implicated, the mechanisms responsible for human embryo developmental arrest remain poorly characterized.