Aneuploidy in oocytes from women of advanced maternal age: analysis of the causal meiotic errors and impact on embryo development.

STUDY QUESTION: In oocytes of advanced maternal age (AMA) women, what are the mechanisms leading to aneuploidy and what is the association of aneuploidy with embryo development? SUMMARY ANSWER: Known chromosome segregation errors such as precocious separation of sister chromatids explained 90.4% of abnormal chromosome copy numbers in polar bodies (PBs), underlying impaired embryo development. WHAT IS KNOWN ALREADY: Meiotic chromosomal aneuploidies in oocytes correlate with AMA (>35 years) and can affect over half of oocytes in this age group. This underlies the rationale for PB biopsy as a form of early preimplantation genetic testing for aneuploidy (PGT-A), as performed in the 'ESHRE STudy into the Evaluation of oocyte Euploidy by Microarray analysis' (ESTEEM) randomized controlled trial (RCT). So far, chromosome analysis of oocytes and PBs has shown that precocious separation of sister chromatids (PSSC), Meiosis II (MII) non-disjunction (ND), and reverse segregation (RS) are the main mechanisms leading to aneuploidy in oocytes. STUDY DESIGN, SIZE, DURATION: Data were sourced from the ESTEEM study, a multicentre RCT from seven European centres to assess the clinical utility of PGT-A on PBs using array comparative genomic hybridization (aCGH) in patients of AMA (36-40 years). This included data on the chromosome complement in PB pairs (PGT-A group), and on embryo morphology in a subset of embryos, up to Day 6 post-insemination, from both the intervention (PB biopsy and PGT-A) and control groups. PARTICIPANTS/MATERIALS, SETTING, METHODS: ESTEEM recruited 396 AMA patients: 205 in the intervention group and 191 in the control group. Complete genetic data from 693 PB pairs were analysed. Additionally, the morphology from 1034 embryos generated from fertilized oocytes (two pronuclei) in the PB biopsy group and 1082 in the control group were used for statistical analysis. MAIN RESULTS AND THE ROLE OF CHANCE: Overall, 461/693 PB pairs showed abnormal segregation in 1162/10 810 chromosomes. The main observed abnormal segregations were compatible with PSSC in Meiosis I (MI) (n = 568/1162; 48.9%), ND of chromatids in MII or RS (n = 417/1162; 35.9%), and less frequently ND in MI (n = 65/1162; 5.6%). For 112 chromosomes (112/1162; 9.6%), we observed a chromosome copy number in the first PB (PB1) and second PB (PB2) that is not explained by any of the known mechanisms causing aneuploidy in oocytes. We observed that embryos in the PGT-A arm of the RCT did not have a significantly different morphology between 2 and 6 days post-insemination compared to the control group, indicating that PB biopsy did not affect embryo quality. Following age-adjusted multilevel mixed-effect ordinal logistic regression models performed for each embryo evaluation day, aneuploidy was associated with a decrease in embryo quality on Day 3 (adjusted odds ratio (aOR) 0.62, 95% CI 0.43-0.90), Day 4 (aOR 0.15, 95% CI 0.06-0.39), and Day 5 (aOR 0.28, 95% CI 0.14-0.58). LIMITATIONS, REASON FOR CAUTION: RS cannot be distinguished from normal segregation or MII ND using aCGH. The observed segregations were based on the detected copy number of PB1 and PB2 only and were not confirmed by the analysis of embryos. The embryo morphology assessment was static and single observer. WIDER IMPLICATIONS OF THE FINDINGS: Our finding of frequent unexplained chromosome copy numbers in PBs indicates that our knowledge of the mechanisms causing aneuploidy in oocytes is incomplete. It challenges the dogma that aneuploidy in oocytes is exclusively caused by mis-segregation of chromosomes during MI and MII. STUDY FUNDING/COMPETING INTEREST(S): Data were mined from a study funded by ESHRE. Illumina provided microarrays and other consumables necessary for aCGH testing of PBs. None of the authors have competing interests. TRIAL REGISTRATION NUMBER: Data were mined from the ESTEEM study (ClinicalTrials.gov Identifier NCT01532284).

Improving access to ART in low-income settings through knowledge transfer: a case study from Zimbabwe.

It may be assumed that infertility is not a problem in resource-poor areas where fertility rates are high. However, evidence overwhelmingly shows that childlessness is highly stigmatized in these settings and that women who are unable to bear children suffer significant social and psychological consequences. The World Health Organization has recommended that infertility be considered a global health problem and stated the need for ART to be adapted to low-resource settings. This paper describes a model for improving access to ART in low-resource settings. Experienced ART health professionals from Australia and Italy representing medical science, embryology, nursing and counselling used knowledge transfer to support a clinician, a laboratory scientist and a nurse to establish an ART service in Harare, Zimbabwe. Support and mentorship provided between October 2016 and December 2017 included: hosting the clinician and the embryologist for the new service in established ART clinics for short periods and providing them with dedicated mentorship and training during their stay; funding an experienced embryologist to travel to Zimbabwe (three times) to oversee the setting up of the lab and provide hands-on embryology training; funding a scientist and a nurse to travel to Zimbabwe to troubleshoot and establish protocols for record keeping and psychosocial care; and contributing approximately AUD $15,000 to the purchase of some equipment. By 31 March 2018, the team at IVF Zimbabwe had performed 166 ART procedures, which at time of writing had resulted in 16 births and 4 ongoing pregnancies. This case study demonstrates that with mentorship and modest financial support from ART experts from high-income settings, health professionals in low-income settings can deliver affordable ART with successful outcomes.

A Bayesian network model for predicting pregnancy after in vitro fertilization.

We present a Bayesian network model for predicting the outcome of in vitro fertilization (IVF). The problem is characterized by a particular missingness process; we propose a simple but effective averaging approach which improves parameter estimates compared to the traditional MAP estimation. We present results with generated data and the analysis of a real data set. Moreover, we assess by means of a simulation study the effectiveness of the model in supporting the selection of the embryos to be transferred.

3D localization of pronuclei of human zygotes using textures from multiple focal planes.

We propose a technique for recovering the position and depth of pronuclei of human zygotes, from Z-stacks acquired using Hoffman Modulation Contrast microscopy. We use Local Binary Pattern features for describing local texture, and integrate information from multiple neighboring areas of the stack, including those where the object to be detected would appear defocused; interestingly, such defocused areas provide very discriminative information for detection. Experimental results confirm the effectiveness of our approach, which allows one to derive new 3D measurements for improved scoring of zygotes during In Vitro Fertilization.

Predictability of preimplantation genetic diagnosis of aneuploidy and translocations on prospective attempts.

The aim of this study was to determine if the outcomes of aneuploidy and translocation testing by preimplantation genetic diagnosis (PGD) at the 8-cell stage have a predictive value for new genetic diagnosis cycles. In total, 83 cycles (39 patients) undergoing PGD of translocations and 378 cycles (176 patients) of aneuploidy were included. Predictability, defined as having similar rate (+/-20%) of euploid embryos in the first and successive cycles, was found in 66% of patients undergoing aneuploidy testing. Predictability was found significantly more often in patients undergoing PGD of translocations (90%, P = 0.006). In addition, patients with 0, <30 or > or =30% euploid embryos in the first cycle were compared and groups 0 and <30% had significantly fewer euploid embryos in the second cycle (22-26%) than those of the group with > or =30% (37%) (P < 0.05). Patients who did not become pregnant after the first attempt were stimulated more aggressively than those becoming pregnant, producing significantly more embryos in the second than in the first cycle (P < 0.001). Therefore, correlation between euploidy rate and pregnancy rate could not be assessed objectively between cycles. In conclusion, the PGD results of a first cycle can predict the results of the second cycle, but this is likely to be of more value when the condition investigated is translocation rather than aneuploidy. The chance of pregnancy is usually related to the number of euploid embryos.

Frequency of hyper-, hypohaploidy and diploidy in ejaculate, epididymal and testicular germ cells of infertile patients.

The hypothesis that sperm aneuploidy and diploidy increase as a function of spermatogenesis impairment was addressed. Ejaculated semen samples from a series of men (n = 22) with very low total normal motile count (1 x 10(6)) was analysed in terms of sperm aneuploidy and diploidy by in-situ hybridization and compared with controls (n = 10). Germ cell aneuploidy was also analysed in an additional series of infertile patients presenting unexplained infertility (n = 3), congenital absence of the vas deferens (CAVD) (n = 6) and non-obstructive azoospermia (n = 3) undergoing IVF, microsurgical epididymal sperm aspiration (MESA)/ICSI and testicular sperm extraction (TESE)/ICSI cycles respectively. In-situ hybridization for chromosomes 1, 17, X and Y was performed on ejaculate, epididymal and testicular spermatozoa. Significantly higher sperm aneuploidy and diploidy rates where found (for the four chromosomes analysed) in spermatozoa from oligoasthenoteratozoospermia (OAT) over controls (18 versus 2.28% and 2.8 versus 0.13% respectively; P < 0.001). Testicular germ cells had even higher rates of sperm aneuploidy and diploidy. However, in this group it was difficult to determine whether the cells analysed were dysmorphic spermatozoa or spermatids. The data warrant further investigation on the cytogenetic abnormalities found in most germ cells identified in testicular tissue biopsies of azoospermic patients.

Effect of recombinant human gonadotrophins on human, bovine and murine oocyte meiosis, fertilization and embryonic development in vitro.

The response of murine, bovine and human oocytes to pure recombinant preparations of human follicle stimulating hormone (rFSH) and luteinizing hormone (rLH) for meiotic maturation and subsequent developmental competence in vitro were examined in the present experiments. Maturation of immature bovine oocytes to the metaphase II stage was significantly increased by the addition of 1 IU/ml of rFSH in combination with either 1 IU/ml rLH or 10 IU/ml rLH. Similarly, embryonic development to the blastocyst stage was improved in bovine oocytes treated with a 1:10 combination of rFSH:rLH. However, no significant difference was observed in the number of inner cell mass or trophectoderm cells of the resulting blastocysts. Although the increased maturation to metaphase II was not significant, human embryonic developmental competence was improved by maturing oocytes in the presence of a 1:10 ratio of rFSH:rLH as only those oocytes exposed to a 1:10 ratio of rFSH: rLH during maturation showed normal cleavage patterns beyond day 2. In addition, 1 IU/ml rFSH and 1 IU/ml rLH increased the expression of oocyte proteins in human oocytes. The inclusion of recombinant gonadotrophins, either singly or in combination, had no significant effect on the maturation, fertilization or embryonic development of in-vitro matured mouse oocytes. These data provide support for the responsiveness of human and bovine oocytes to gonadotrophins in vitro and the need to consider variations in the relative concentrations for optimization of oocyte developmental competence.

Birth following vitrification of a small number of human oocytes: case report.

We report the birth of a healthy baby girl at 37 weeks gestation to a 47 year old recipient, after vitrification of mature oocytes from four in-vitro fertilization (IVF) patients. A total of 17 oocytes was vitrified in 1-2 microl of ethylene glycol (40%) and 0.6 mol/l sucrose (20.54%) in open pulled straws. Eleven oocytes survived after vitrification and five pronuclear zygotes were obtained after intracytoplasmic sperm injection (ICSI). Three embryos were transferred to three patients, two of whom were the original oocyte donors and pregnancy was not established. The third embryo was donated to a 47 year old infertile woman after preimplantation diagnosis had confirmed euploidy for chromosomes X, 13, 14, 15, 16, 18, 21 and 22. The successfully completed pregnancy is encouraging for further research to explore the potential benefits of vitrification for the cryopreservation of human oocytes, given the relatively low success of conventional freezing of human oocytes by slow cooling methods.

Positive outcome after preimplantation diagnosis of aneuploidy in human embryos.

usromosomal abnormalities are responsible for a great deal of embryo wastage, which is reflected, at least partially, in decreased implantation and increased miscarriage in older women. To address this problem the transfer of only chromosomally normal embryos previously selected by preimplantation genetic diagnosis (PGD) has been proposed. We designed a multi-centre in-vitro fertilization (IVF) study to compare controls and a test group that underwent embryo biopsy and PGD for aneuploidy. Patients were matched retrospectively, but blindly, for average maternal age, number of previous IVF cycles, duration of stimulation, oestradiol concentrations on day +1, and average mature follicles. All these parameters were similar in test and control groups. Only embryos classified as normal for those chromosomes were transferred after PGD. The results showed that the rates of fetal heart beat (FHB)/embryo transferred between the control and test groups were similar. However, spontaneous abortions, measured as FHB aborted/FHB detected, decreased after PGD (P < 0.05), and ongoing pregnancies and delivered babies increased (P < 0.05) in the PGD group of patients. Two conclusions were obtained: (i) PGD of aneuploidy reduced embryo loss after implantation; (ii) implantation rates were not significantly improved, but the proportion of ongoing and delivered babies was increased.

Elective cryopreservation of all pronucleate embryos in women at risk of ovarian hyperstimulation syndrome: efficiency and safety.

In a prospective randomized study, we analysed 125 patients at risk of ovarian hyperstimulation syndrome (OHSS), selected in the period between January 1996 and July 1997. All the patients had blood oestradiol concentration >/=1500 pg/ml on the day of human chorionic gonadotrophin (HCG) administration and >/=15 oocytes were collected. The patients were matched in two groups: group A, control group (n = 67), had fresh embryo transfers; group B (n = 58) had cryopreservation of all obtained pronucleate embryos. Pregnancy, live birth rates and the incidence of OHSS were compared between the two groups. There were no significant differences in terms of pregnancies per patient (46.3 versus 48.3%) and live birth rates (38. 8 versus 39.6%). No cases of OHSS occurred in group B, while four patients developed the syndrome in group A. The implantation rate was slightly but not significantly lower in group B (chi2 = 1.03). These results suggest that elective cryopreservation of all zygotes might prevent the risk of OHSS in patients undergoing IVF treatment. In contrast to what has been reported by other authors, our results show that the elective cryopreservation of zygotes does not affect pregnancy and live birth rates.

Scoring criteria for preimplantation genetic diagnosis of numerical abnormalities for chromosomes X, Y, 13, 16, 18 and 21.

Fluorescence in-situ hybridization (FISH) for application in preimplantation genetic diagnosis (PGD) of aneuploidy has been used successfully, but stringent scoring criteria to score FISH signals have not been developed. In the present study a FISH protocol to simultaneously enumerate chromosomes X, Y, 13, 16, 18, and 21 was used to evaluate two different scoring criteria. The criteria consider hybridization signal size, shape, and vicinity to other signals and nuclear diameter. For this purpose, 74 embryos (412 blastomeres) donated for research had most or all of their cells analysed. The least error-prone criterion (9%) was selected for use in PGD cases. Some probes produced more errors than others, and these criteria may provide clues to improve these probes. The same probe solution was applied to 55 PGD cases and a total of 307 embryos. Of the non-transferred embryos, 67 were fully reanalysed and 1.5% (1/67) of them were falsely diagnosed as normal, while 19% (13/67) were falsely diagnosed as abnormal. Twelve of the patients became pregnant after PGD.

Preimplantation diagnosis of the aneuploidies most commonly found in spontaneous abortions and live births: XY, 13, 14, 15, 16, 18, 21, 22.

The present preimplantation diagnosis test is able to screen for the most common aneuploidies from single blastomeres in about five hours with a 15 per cent misdiagnosis. This means that the risk of spontaneous abortion and trisomic offspring for women of advanced maternal age could be reduced to the same level as younger women for whom prenatal diagnosis is usually not necessary. Better probes and more fluorochromes could improve the success rate of the test.

Treatment-related chromosome abnormalities in human embryos.

Mosaicism was studied in good quality embryos from four different centres in order to assess the effects of follicular induction and exposure to laboratory conditions on chromosomal status. The donated embryos were fully biopsied and analysed by fluorescence in-situ hybridization using probes for chromosomes X, Y, 13, 18 and 21, simultaneously. The number of abnormal cells present indicated the division at which mosaicism first occurred (4/4 cells at first division, 2/4 cells at second, 2/8 at third). The rate of mosaicism in embryos from different centres varied greatly (P < 0.001). Most of the mosaic embryos were obtained before 1991. In one clinic increased mosaicism was found in embryos obtained before 1991 when compared to embryos obtained thereafter. The results suggest that certain culture conditions and/or hormonal stimulation protocols may induce chromosomal abnormalities and partly explain differences in pregnancy rates between in-vitro fertilization centres.

Relationship of timing of agonist administration in the cycle phase to the ovarian response to gonadotropins in the long down-regulation protocols for assisted reproductive technologies.

OBJECTIVE: To assess whether the ovarian response to exogenous gonadotropins and cycle performance is affected by different timing of an agonist administration in long down-regulation protocols. DESIGN: An agonist was administered irrespective of cycle phase, with exogenous gonadotropin beginning 15 days later. PATIENTS: Five hundred fifty-seven normovulatory infertile patients, aged < or = 38 years, were classified into seven study groups, depending on the phase of the cycle in which agonist was started. MAIN OUTCOME MEASURES: Endocrine profile, amount of exogenous stimulation, occurrence of ovarian cysts, mean number of oocytes recovered and embryos transferred, pregnancy rate, implantation rate, and live-birth rate of the seven groups. RESULTS: The ovarian response of the groups did not show any statistically significant differences in relation to the initiation of the agonist. The only effect was a different incidence of ovarian cyst formation, but this phenomenon did not affect cycle performance. The pregnancy, implantation, and live-birth rates showed differences that did not reach statistical significance. CONCLUSION: Agonists initiation can be programmed in advance irrespective of the phase of the cycle. This approach can be of help for the logistics of assisted reproduction programs.

Fertilization current in the human oocyte.

In this report we show that the first event of activation in the human oocyte, the Fertilization current (FC), is a slow transient outward current of 300 pA, which induces a gradual hyperpolarization of the plasma membrane from -20mV to -60mV, 60-120 min after insemination, followed by a repolarization to -20mV. Activation currents (AC) of 600-2,500 pA, induced by exposure to the calcium ionophore A23187 or by microinjection of InsP3 into the cytosol, are also outward. The AC are inhibited by preloading oocytes with EGTA suggesting they are calcium dependent. Since AC are 2-10-fold the amplitude of the FC the fertilizing spermatozoon in the human only activates a portion of the primary elements stored in the oocyte for triggering metabolic depression. Oocyte activation in the human resembles that in the hamster rather than other mammals or invertebrates studied to date.

Prospective randomized study of D-Trp6-LHRH versus buserelin in long desensitization protocols for medically assisted conception cycles.

In a prospective, controlled, randomized study where two different agonists were used, we compared three different long desensitization protocols for induction of multiple follicular growth in medically assisted conception cycles. In protocol A, 30 patients were injected with buserelin twice a day for 15 days prior to ovarian stimulation until human chorionic gonadotrophin (HCG) administration. In protocol B, 30 patients were injected with a single dose of long acting Triptorelin (3.75 mg) 15 days before the ovarian stimulation onset. In protocol C, 30 patients were injected with the long acting Triptorelin 4 weeks before ovarian stimulation followed by daily administration of 0.1 mg of the same agonist until HCG injection. There was no difference in the ovarian response to exogenous gonadotrophin stimulation, except for the presence of premature luteinization in two patients in group B. A significantly higher number of mature oocytes was collected from patients with protocol A; however, the fertilization and cleavage rate demonstrated no significant difference among the three groups of patients. The ongoing pregnancy rate and the implantation rate per treatment cycle were very similar in the three study groups. When the convenience, cost and side-effects for the patient are being considered, protocol B should be selected as the first choice when the agonist is utilized for the purpose of inducing pituitary desensitization before and during ovarian stimulation.

Erythropoietin production in the rat: additive role of kidney and liver.

Erythropoietin (Ep) levels were evaluated in serum of neonate, weanling, or adult rats subjected to 1) sham operation, nephrectomy, and/or subtotal hepatectomy and 2) a standard bout of hypoxia (0.45 atm air/6 h, starting 1 h after the operation). Ep activity was quantitated by means of strictly controlled assays in exhypoxic polycythemic mice. The sum of Ep titers in the serum of nephrectomized or hepatectomized rats was compared to Ep levels in sham-operated animals of corresponding age levels, with the exception of 1-wk-old rats: it is relevance that no significant difference is apparent between these Ep production curves. Thus, evidence is presented indicating for the first time that Ep derives from two functionally distinct and additive sources, i.e., the kidney and the liver. Liver Ep, although prevalent in neonatal animals, is obscured in the weanling adult rat by both gradual initiation of massive renal Ep production and progressive decrease of hepatic Ep activity.

Hepatic erythropoietin: enhanced production in anephric rats with hyperplasia of Kupffer cells.

Erythropoietin (Ep) levels were assayed in serum of adult male rats subjected sequentially to (1) administration of colloidal carbon, Zymosan or their vehicles (2) sham operation or bilateral nephrectomy with and without subtotal hepatictomy, and (3) hypoxia (0.45-0.40 atmospheres of air for 6 h starting 1 h after the operation). In anephric rats these agents induced a significant potentiation of hypoxic Ep activity. Since they did not apparently modify the kinetics of exogenous Ep, it is postulated that this phenomenon is mediated by enhanced extrarenal Ep production. Both colloidal carbon and Zymosan induced hyperplasia of the reticuloendothelial system (RES). Moreover, subtotal hepatectomy almost abolished the Ep response to hypoxia evoked by Zymosan. The correlation between hyperplasia of hepatic RES and enhanced Ep production in anephric rats primed with these agents suggests that Kupffer cells constitute a major source for extrarenal Ep. Additionally, it is of interest that colloidal carbon and Zymosan did not significantly modify the renal production of Ep.