Follicular fluid anti-Müllerian hormone: a predictive marker of fertilization capacity of MII oocytes

Oocyte Selection for In Vitro Embryo Production in Bovine Species: Noninvasive Approaches for New Challenges of Oocyte Competence

Simple Summary

The efficiency of producing embryos using in vitro technologies in cattle species remains lower when compared to mice, indicating that the proportion of female gametes that fail to develop after in vitro manipulation is considerably large. Considering that the intrinsic quality of the oocyte is one of the main factors affecting embryo production, the precise identification of noninvasive markers that predict oocyte competence is of major interest. The aim of this review was to explore the current literature on different noninvasive markers associated with oocyte quality in the bovine model. Apart from some controversial findings, the presence of cycle-related structures in ovaries, a follicle size between 6 and 10 mm, a large slightly expanded investment without dark areas, large oocyte diameter (>120 microns), dark cytoplasm, and the presence of a round and smooth first polar body have been associated with better embryonic development. In addition, the combination of oocyte and zygote selection, spindle imaging, and the anti-Stokes Raman scattering microscopy together with studies decoding molecular cues in oocyte maturation have the potential to further optimize the identification of oocytes with better developmental competence for in vitro technologies in livestock species.

Abstract

The efficiency of producing embryos using in vitro technologies in livestock species rarely exceeds the 30–40% threshold, indicating that the proportion of oocytes that fail to develop after in vitro fertilization and culture is considerably large. Considering that the intrinsic quality of the oocyte is one of the main factors affecting blastocyst yield, the precise identification of noninvasive cellular or molecular markers that predict oocyte competence is of major interest to research and practical applications. The aim of this review was to explore the current literature on different noninvasive markers associated with oocyte quality in the bovine model. Apart from some controversial findings, the presence of cycle-related structures in ovaries, a follicle size between 6 and 10 mm, large number of surrounding cumulus cells, slightly expanded investment without dark areas, large oocyte diameter (>120 microns), dark cytoplasm, and the presence of a round and smooth first polar body have been associated with better competence. In addition, the combination of oocyte and zygote selection via brilliant cresyl blue (BCB) test, spindle imaging, and the anti-Stokes Raman scattering microscopy together with studies decoding molecular cues in oocyte maturation have the potential to further optimize the identification of oocytes with better developmental competence for in-vitro-derived technologies in livestock species.

Oocyte matched follicular fluid anti-Müllerian hormone is an excellent predictor of live birth after fresh single embryo transfer

STUDY QUESTION

What is the relationship between the anti-Müllerian hormone (AMH), gonadotropin and androgen concentrations within a single follicle and live birth after ICSI and a transfer of an embryo developed from the matched oocyte?

SUMMARY ANSWER

Among the analysed markers on the day of oocyte retrieval, AMH concentration in follicular fluid (FF) is a predictor of live birth after single embryo transfer (SET).

WHAT IS KNOWN ALREADY

High serum concentrations of AMH and low FSH concentrations have been associated with a high chance of pregnancy after ART. Whether there are differences in the hormonal milieu for individual follicles and whether this impacts the laboratory and clinical outcomes for the individual oocyte developing within that follicle are unknown.

STUDY DESIGN, SIZE, DURATION

This prospective cohort study included 322 individual FF samples from 199 infertile women scheduled for ICSI/SET over an 18-month period. Of these women, 76 provided a single FF sample, while 123 women contributed two FF samples taken from two different follicles.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The first follicle aspirated in each ovary on the day of oocyte retrieval had the FF aspirated; the individual cumulus-oocyte complex (COC) was tracked, and the associated FF was stored at -80°C. FF AMH, FSH, LH, testosterone (T) and androstenedione (A2) levels were measured by mass spectrometry (androgens) and immunoassays. The laboratory and clinical outcomes for each individual oocyte were related to their unique follicle hormone concentrations.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the 322 oocytes with paired FF samples, 70 (21.7%) oocytes did not fertilise. From the remaining 252 2PN embryos, 88 (34.9%) were transferred as single embryos on Day 3; of the remaining 164, 78 developed into blastocysts, and 18 single blastocyst transfers were performed. Thus, a total of 106 transferred embryos had matching FF samples. An analysis of these individual FF concentrations revealed that AMH concentrations were higher in follicles in which the oocyte developed into a top quality (TQ) blastocyst (6.33 ± 5.52 ng/ml) and whose transfer led to live birth (7.49 ± 5.03 ng/ml) than those in which there was a failure of fertilisation (3.34 ± 2.21 ng/ml). In contrast, follicular FSH concentrations were the lower for oocytes that resulted in a TQ blastocyst (5.36 ± 2.20 mIU/ml) and live birth (5.60 ± 1.41 mIU/ml) than for oocytes that failed to fertilise (9.06 ± 3.36 mIU/ml). FF AMH was the only studied marker that increased the chance of live birth (odds ratio: 1.93 [95% CI: 1.40-2.67], P < 0.001). The receiver operating characteristic analysis showed that FF AMH levels predicted live birth with a very high sensitivity (91.2%), specificity (91.7%) and an excellent AUC value of 0.954, whereas serum AMH level only had a fair (AUC = 0.711) significance as a predictor for live birth after ICSI/SET. The predictive capabilities of the interfollicular markers were not limited to the TQ embryos or blastocysts; they applied to all SET cycles.

LIMITATIONS, REASONS FOR CAUTION

Whether an altered intrafollicular hormonal environment reflects the developmental capacity of the oocyte or defines cannot be determined from this cross-sectional analysis. Inclusion of 21 subjects with polycystic ovary syndrome (PCOS) may have biased the findings due to a unique intrafollicular milieu associated with PCOS.

WIDER IMPLICATIONS OF THE FINDINGS

Our results suggest that highly competent human oocytes have an FF composition of AMH, FSH, T and A2 that is close to that in a natural cycle. Also, the relationships between intrafollicular AMH, gonadotropin and androgen levels in the same follicle support the hypothesis that FF AMH concentration may reflect granulosa cell proliferation during gonadotropin-stimulated follicle growth. Finally, the serum AMH concentration is markedly lower than the FF AMH concentration, with a moderate correlation between serum and FF AMH, implying ovarian follicle autonomy with regards to its secretory products.

STUDY FUNDING/COMPETING INTEREST(S)

The National Science Centre of Poland supported this work (grant number: N N407 217 040). The authors declare that there is no conflict of interest regarding the publication of this article.

Genes for anti-Müllerian hormone and androgen receptor are underexpressed in human cumulus cells surrounding morphologically highly graded oocytes

Objectives:

The aim of this study was to investigate the expression of genes crucial for the quality of the oocyte and whether expression levels of these genes in cumulus cells can be biological markers for the quality of the oocyte, zygote or embryo, or even for achievement of pregnancy after the assisted reproductive technology procedure. We examined the expression profile of the anti-Müllerian hormone (AMH) gene and its respective receptors: anti-Müllerian hormone receptor type 2 (AMHR2), follicle-stimulating hormone receptor (FSHR) and androgen receptor (AR) in cumulus cells (CCs) surrounding the oocyte, as well as AMH concentrations in follicular fluid of the associated follicle. The obtained gene expression levels were correlated with the morphological quality of the associated oocyte, zygote and embryo as well as with assisted reproductive technology outcome following the intracytoplasmic sperm injection procedure.

Methods:

This study involved 129 cumulus cells and 35 follicular fluid samples, taken from 58 patients undergoing the intracytoplasmic sperm injection procedure. Oocytes, zygotes and embryos were assessed for morphological quality. The relative gene expression of AMH, AMHR2, FSHR and AR was calculated using the delta–delta Ct method. Anti-Müllerian hormone concentrations in follicular fluids were measured by enzyme-linked immunosorbent assay.

Results:

The results yielded suggest a relationship between AMH, AR and oocyte morphology: AMH and AR gene expression levels in CCs surrounding morphologically optimal oocytes were significantly lower than in CCs surrounding oocytes with suboptimal morphology (p = 0.011 and p = 0.008, respectively). Statistically significant positive correlation was found between mRNA expression levels of AMH and FSHR (p < 0.001), AMH and AR (p = 0.001), AMHR2 and FSHR (p < 0.001), AMHR2 and AR (p < 0.001), as well as between FSHR and AR (p < 0.001).

Conclusion:

Assessed results point to AMH and AR relation with oocyte maturity, but not with its fertilization potential, or with embryo quality.

Oocyte polarized light microscopy, assay of specific follicular fluid metabolites, and gene expression in cumulus cells as different approaches to predict fertilization efficiency after ICSI

BACKGROUND

The complex relationship between oocyte morphology, specific follicular fluid metabolites, gene expression in cumulus granulosa cells, and oocyte competence toward fertilization and embryo development still needs further clarification.

METHODS

Forty-six oocytes retrieved from the largest pre-ovulatory follicle of patients undergoing intra-cytoplasmic sperm injection (ICSI) were considered assessing: (a) oocyte morphological characteristics at polarized light microscopy (PLM), (b) specific follicular fluid (FF) metabolites previously suggested to influence oocyte competence (AMH, markers of redox status and of cytotoxicity), (c) transcription of AMH and AMH type II receptor genes in cumulus cells. Data were analyzed using mono-parametric tests and multivariable logistic analysis in order to correlate morphological and biochemical data with fertilization.

RESULTS

Comparing normally fertilized oocytes (n = 29, F group) with unfertilized (n = 17, nF group) we observed that: (a) the meiotic spindle area and major axis were significantly higher in nF group and in fertilized oocytes undergoing an early embryo development arrest; (b) AMH level in FF was comparable in F and nF groups; (c) the FF of nF group contained significantly higher levels of cytotoxicity (lactate dehydrogenase) and oxidative stress (Cu,Zn-superoxide dismutase, catalase, 4-hydroxynonenal-protein conjugates) markers; (d) cumulus cells of nF group showed significantly higher AMH receptor type II gene expression.

CONCLUSIONS

Taken together, these observations suggest that an excessive cytotoxicity level can alter AMH signal transduction within cumulus cells, in turn leading to partial inhibition of aromatase activity, altered cytoplasmic maturation and increased oxidative stress, factors able to impair oocyte fertilization competence and embryo growth.

Anti-Mullerian hormone concentrations in individual follicular fluids within one stimulated IVF cycle resemble blood serum values

Purpose

Anti-Mullerian hormone (AMH) is commonly known as the most potent marker for ovarian reserve due to its decline as female age increases. While serum AMH (sAMH) levels have been intensively investigated, there is less data regarding AMH concentrations in follicular fluid (FF), since FF has usually been designated as waste product during oocyte collection in assisted reproductive technologies. This pilot study investigated follicle AMH concentrations (fAMH) of several follicles per ovary, individually collected with the Steiner-Tan needle, and compared them to sAMH concentrations in women undergoing IVF treatment. We hypothesized that there is no difference of fAMH concentrations in individual follicles and that these concentrations resemble the sAMH value of the patient.

Methods

Patients were stimulated with a gonadotropin-releasing hormone antagonist ovarian hyperstimulation protocol. On the day of oocyte retrieval, serum samples and FF from all individual follicles from one stimulated IVF cycle were collected and individually analyzed for AMH concentrations.

Results

Intracyclic mean fAMH values (n_follicle = 2–14) were significantly correlated to sAHM values (ρ = 0.85, p < 0.001) and showed a trend to be negatively associated with age (ρ = −0.43, p = 0.06). Mean intrapatient fAMH concentrations differed significantly (p < 0.001). Furthermore, significant correlations of sAMH with individual fAMH values of the first five follicles of each patient were observed.

Conclusions

In conclusion, our results clearly showed that individual fAMH concentrations reflected sAMH values and that fAMH concentrations did not significantly differ within one patient. In future studies, it will be interesting to correlate individual fAMH values to the respective embryo development and overall pregnancy outcome in order to improve IVF treatments and to refrain from embryo overproduction.