Oocyte maturity in repeated ovarian stimulation

Oocyte rescue in-vitro maturation does not adversely affect chromosome segregation during the first meiotic division

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; n = 137) or without them (IVM-CC; n = 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%, P = 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 (P = 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.

Oocyte maturity, oocyte fertilization and cleavage-stage embryo morphology are better in natural compared with high-dose gonadotrophin stimulated IVF cycles

RESEARCH QUESTION

Does high-dose gonadotrophin stimulation have an effect on oocyte and early-stage embryo development?

DESIGN

This was a retrospective study including 616 natural cycle IVF (NC-IVF) and 167 conventional IVF (cIVF) cycles. In total, 2110 oocytes were retrieved and analysed in fresh cycles. In NC-IVF, only human chorionic gonadotrophin was applied to trigger ovulation. In cIVF, antagonist protocols with daily 150-300 IU of human menopausal gonadotrophins were performed. The effect of gonadotrophins on oocyte and early-stage embryo development was analysed. Primary outcomes were the occurrence of mature (metaphase II) oocytes, zygotes and embryos with good morphology at the cleavage stage 2 days after oocyte retrieval.

RESULTS

The mature oocyte rate (number of mature oocytes/number of retrieved oocytes) was higher in NC-IVF than cIVF cycles (89% versus 82%, adjusted odds ratio [aOR] 1.79, P = 0.001), as was the zygote rate per oocyte retrieved (70% versus 58%, aOR 1.76, P = 0.001) and the zygote rate per mature oocyte (79% versus 71%, aOR 1.62, P = 0.001). The percentage of zygotes that developed into cleavage-stage embryos was no different. For the transferred embryos, the probability of having a good embryo morphology with four blastomeres and a fragmentation of <10% (score 0) in cleavage-stage embryos was found to be higher in NC-IVF (proportional aOR for four blastomeres 2.00, P < 0.001; aOR 1.87 for a fragmentation score of 0, P = 0.003).

CONCLUSIONS

Oocyte maturity, oocyte fertilization and morphology of the cleavage-stage embryo are affected by high-dose gonadotrophin stimulation in fresh IVF cycles.

Ultrastructural Evaluation of the Human Oocyte at the Germinal Vesicle Stage during the Application of Assisted Reproductive Technologies

After its discovery in 1825 by the physiologist J.E. Purkinje, the human germinal vesicle (GV) attracted the interest of scientists. Discarded after laparotomy or laparoscopic ovum pick up from the pool of retrieved mature oocytes, the leftover GV was mainly used for research purposes. After the discovery of Assisted Reproductive Technologies (ARTs) such as in vitro maturation (IVM), in vitro fertilization and embryo transfer (IVF-ET) and intracytoplasmic sperm injection (ICSI), its developing potential was explored, and recognized as an important source of germ cells, especially in the case of scarce availability of mature oocytes for pathological/clinical conditions or in the case of previous recurrent implantation failure. We here review the ultrastructural data available on GV-stage human oocytes and their application to ARTs.

Generation of cynomolgus monkey fetuses with intracytoplasmic sperm injection based on the MII-stage oocytes acquired by personalized superovulation protocol

Background

Mature oocytes at the metaphase II status (MII-stage oocytes) played an important role in assisted reproductive technology in non-human primates.

Objectives

In order to improve the proportion of MII-stage oocytes retrieval, three different superovulation protocols were performed on 24 female cynomolgus monkeys.

Methods

All the monkeys received once-daily injection of follicle-stimulating hormone (25 international unit [IU]) on day 3 of the menstruation, 3-day intervals, twice daily for 8–12 days until the time of human chorionic gonadotropin (1,500 IU) injection, on the 14–17th day of menstruation collecting oocytes. The difference between protocol I and protocol II was that 0.1 mg the gonadotropin-releasing hormone agonist was injected on day 1 of the menstruation, while the difference between personalized superovulation protocol and protocol II was that oocytes could be collected on the 14–17th day of menstrual cycle according to the length of each monkey.

Results

The total number of oocytes harvested using the personalized superovulation protocol was much higher than that using protocol I (p < 0.05), and the proportion of MII-stage oocytes was significantly greater than that from either superovulation protocol I or II (p < 0.001 and p < 0.01 respectively), while the proportion of immature oocytes at the germinal vesicle was less than that from superovulation protocol I (p < 0.05).

Conclusions

The personalized superovulation protocol could increase the rate of MII-stage oocytes acquired, and successfully develop into embryos after intracytoplasmic sperm injection, and eventually generated fetus.

Impact of Serum Human Chorionic Gonadotropin and Luteinizing Hormone Receptor Expression to Oocyte Maturation Rate: A Study of Controlled Ovarian Stimulation

Background:

Few studies have assessed the impact of serum human chorionic gonadotropin (hCG) levels before oocyte retrieval and luteinizing hormone receptor (LHR) mRNA expression.

Aims:

The objective was to assess the correlations between serum hCG levels at 12-h posttrigger granulosa cell LHR mRNA expression during the in vitro fertilization (IVF) cycle with oocyte maturation rate and to determine the cutoff level of serum hCG at 12-h posttrigger.

Settings and Design:

A cross-sectional was conducted for this study at the IVF center of Dr. Cipto Mangunkusumo General Hospital, Jakarta, Indonesia.

Materials and Methods:

Recombinant follicle-stimulating hormone was used on day 2 of the menstrual cycle with multiple doses of a gonadotropin-releasing hormone antagonist. Recombinant hCG was used to trigger ovulation. At 12-h posttrigger, hCG serum levels were measured using an enzyme-linked immunosorbent assay.

Statistical Analysis:

Pearson's correlation coefficient was used to evaluate the correlation between oocyte maturation rates, serum hCG levels, and LHR mRNA levels. Cutoff values were determined using a receiver operating characteristic (ROC) curve.

Results:

Serum hCG levels were positively correlated (r = 0.467;P < 0.01), and LHR mRNA expression was weakly correlated (r = 0.073; P = 0.701) with oocyte maturation. The cutoff of serum hCG for a high maturation rate was 77 mIU/mL, with an area under the ROC curve of 0.765 (95% confidence interval: 0.598–0.939) andP < 0.001.

Conclusion:

Oocyte maturation is correlated with serum hCG levels with 77 mIU/mL as the cutoff point for oocyte retrieval.

[Dual trigger with gonadotropin-releasing hormone agonist and hCG to improve oocyte maturation rate]

OBJECTIVE

This study investigates dual trigger with GnRHa and hCG as a potential treatment in patients with a history of ≥25 % immature oocytes retrieved in IVF/ICSI cycles.

METHODS

This is a retrospective case-control study performed between October 2008 and December 2017. Forty-seven patients who experienced high oocyte immaturity rate (≥25 %) during their first IVF/ICSI cycle (analyzed as control group) and received a dual trigger for their subsequent cycle, were involved. During dual trigger cycles, patients received antagonist protocol and ovulation triggering using triptorelin 0.2mg and hCG. Primary endpoint was maturation rate (MR). Secondary endpoints were fertilization, D2 top quality embryo (TQE) rates, clinical pregnancy rate per fresh embryo transfer and cumulative clinical pregnancy rate per couple.

RESULTS

A significant increase in MR was achieved in case of dual trigger (71.0 %) when compared to control group (47.8 %; P<0.0001). Moreover, cumulative clinical pregnancy rate yielded 46.8 % in dual trigger group, which was statistically higher than 27.6 % obtained in control group (P=0.05). However, fertilization, D2 TQE rates and clinical pregnancy rates/transfer were statistically similar when compared between the two groups.

CONCLUSION

Dual trigger seems efficient for managing patients with high oocyte immaturity rate.

Ddx4+ Oogonial Stem Cells in Postmenopausal Women's Ovaries: A Controversial, Undefined Role

Recent studies support the existence of oogonial stem cells (OSCs) in the ovarian cortex of different mammals, including women.These cells are characterized by small size, membrane expression of DEAD(Asp-Glu-Ala-Asp)-box polypeptide-4 (Ddx4), and stemness properties (such as self-renewal and clonal expansion) as well as the ability to differentiate in vitro into oocyte-like cells. However, the discovery of OSCs contrasts with the popular theory that there is a numerically defined oocyte pool for female fertility which undergoes exhaustion with menopause. Indeed, in the ovarian cortex of postmenopausal women OSCs have been detected that possess both viability and capability to differentiate into oocytes, which is similar to those observed in younger patients. The pathophysiological role of this cell population in aged women is still debated since OSCs, under appropriate stimuli, differentiate into somatic cells, and the occurrence of Ddx4⁺ cells in ovarian tumor samples also suggests their potential involvement in carcinogenesis. Although further investigation into these observations is needed to clarify OSC function in ovary physiology, clinical investigators and researchers studying female infertility are presently focusing on OSCs as a novel opportunity to restore ovarian reserve in both young women undergoing early ovarian failure and cancer survivors experiencing iatrogenic menopause.

Luteinizing Hormone Receptor Gene and Regulator of G-protein Signaling 2 Gene Expression Level and Association with Oocyte Maturity in In vitro Fertilization/Intracytoplasmic Sperm Injection Cycle

Aims:

The aim is to study the relation and distribution in gene expression level of the luteinizing hormone receptor (LHR) gene and regulator of G-protein signaling 2 (RGS2) gene expression with oocyte maturation.

Setting and Design:

This cross-sectional study was undertaken in an instruction-based tertiary care infertility unit, department of obstetrics and gynecology.

Materials and Methods:

After controlled ovarian hyperstimulation, cumulus granulosa cells (CCs) from 59 oocytes among 18 women being treated by in vitro fertilization/intracytoplasmic sperm injection cycle technique from November 2015 to January 2016 were collected on the day of oocyte retrieval. Total RNA was extracted and converted to cDNA in individual oocytes. LHR and RGS2 gene levels were measured and analyzed using digital droplet polymerase chain reaction.

Statistical Analysis:

Gene expression level was analyzed using software STATA, version 14.0 (College Station, TX: StataCorp LP, USA).

Results:

CCs were obtained from 59 cumulus-oocyte complexes (COC), 46 COC from metaphase II (CC_MII), 13 COC from metaphase I, and GV oocyte (CC_{MI + GV}). The RGS2 gene expression level, when compared with the housekeeping gene in CC_MII and CC_{MI + GV}, was 0.15 (0.05–0.52) and 0.08 (0.02–0.27), respectively. The LHR gene expression when compared with the housekeeping gene in CC_MII and CC_{MI + GV} did not differ and was quite in the same value that was 0.02 (0.00–0.11) and 0.02 (0.00–0.06), respectively.

Conclusion:

This study showed that LHR gene expression did not differ in between oocyte groups. Even though the median of RGS2 gene expression was more in the mature oocyte group, the result was inconclusive due to scattering and overlapping of gene expression data between oocyte groups.

Serum substance P concentrations to predict oocyte maturation index and clinical pregnancy

AIM

The aim of this study was to assess the predictive value of serum substance P (SP) concentrations on oocyte maturation and clinical pregnancy.

METHODS

Ninety-three women with unexplained infertility underwent intracytoplasmic sperm injection (ICSI) cycles. Antagonist protocol was started for each participant and at the day of oocyte pick up, serum samples were obtained from each participant to assess SP concentrations, and these concentrations were utilized to predict mature/total oocyte ratio and clinical pregnancy.

RESULTS

SP concentration was a significant predictor for mature/total oocyte ratio > 0.75 and clinical pregnancy. In correlation analyses, maturation index was significantly correlated with FSH (r= -0.226, p = 0.03), estradiol (r = 0.239, p = 0.021), peak estradiol (r = 0.414, p < 0.001), and substance P (r = 0.796, p < 0.001). In multivariate analyses, number of immature (beta coefficient = -0.379, p < 0.001), mature oocyte (beta coefficient = 0.473, p < 0.001), SP concentration (beta coefficient = 0.723, p < 0.001) and maturation index (beta coefficient = -0.387, p = 0.003) were significantly associated with clinical pregnancy.

CONCLUSION

SP concentrations at the day of oocyte pick up may be used to predict clinical pregnancy and may be an indirect indicator for cycle outcome in assisted reproductive technology (ART).

Developmental potential of in vitro or in vivo matured oocytes

This study compared the embryological features of mature and immature oocytes (different stages) collected from stimulated cycles of in vitro fertilization (IVF). Immature oocytes were identified, classified as PI (prophase I – germinal vesicle, GV) or MI (metaphase I), were matured in vitro and fertilized using the intra-cytoplasmic sperm injection (ICSI) technique. Fertilization potential, cleavage, and subsequent transfer/cryopreservation of the embryos derived from these in vitro matured oocytes were compared with those of in vivo matured oocytes (collected at the MII stage). The characteristics of embryos derived from gametes recovered in the MI and MII stages were similar. The fertilization rate of immature oocytes recovered in PI was significantly lower than that of MII oocytes (P = 0.031), and the cleavage rate of the PI group was also lower than that of the MI (P = 0.004) and MII (P < 0.001) groups. In vitro maturation of MI oocytes is a suitable alternative when immature oocytes are recovered, as their characteristics and development are similar to those of in vivo matured oocytes. Optimization of outcomes for PI oocytes will require development of techniques that can distinguish which of these gametes will mature and fertilize.

Serum human chorionic gonadotropin levels on the day before oocyte retrieval do not correlate with oocyte maturity

OBJECTIVE

To evaluate the correlation of preretrieval quantitative serum hCG level with oocyte maturity.

DESIGN

Retrospective cohort study.

SETTING

Military assisted reproductive technology (ART) program.

PATIENT(S)

Fresh autologous ART cycles.

INTERVENTION(S)

Serum hCG level the day before oocyte retrieval.

MAIN OUTCOME MEASURE(S)

Linear regression was used to correlate serum hCG levels and oocyte maturity rates. Normal oocyte maturity was defined as ≥75% and the Wilcoxon rank sum test was used to compare serum hCG levels in patients with normal and low oocyte maturity. Threshold analysis was performed to determine hCG levels that could predict oocyte maturity.

RESULT(S)

A total of 468 ART cycles were analyzed. Serum hCG level was not correlated with hCG dose; however, it was negatively correlated with body mass index (BMI). Serum hCG levels did not differ between patients with oocyte maturity of <75% and ≥75%. Serum hCG levels did not correlate with oocyte maturity rates. Receiver operator characteristic and less than efficiency curves failed to demonstrate thresholds at which hCG could predict oocyte maturity.

CONCLUSION(S)

Serum hCG levels were not correlated with oocyte maturity. Although a positive hCG was reassuring that mature oocytes would be retrieved for most patients, the specific value was not helpful.