State of the art in in-vitro oocyte maturation

The Effect of Wharton's Jelly-Derived Conditioned Medium on the In Vitro Maturation of Immature Oocytes, Embryo Development, and Genes Expression Involved in Apoptosis

Oocyte cytoplasmic maturation is a crucial process during in vitro maturation (IVM), and finding an appropriate IVM medium that promotes oocyte competence is very critical in assisted reproductive technology (ART). The aim of this study was to investigate the effects of umbilical cord Wharton's jelly (WJ-MSCs)-derived conditioned media on the maturation of immature oocytes and their developmental potential in humans after IVM, as well as apoptotic gene expression. A total of 392 germinal vesicle (GV) oocytes were collected from 207 women aged 25-35 years and divided into two IVM groups: (1) control group, which was cultured in CleavTM medium, and (2) experimental group, which was cultured in supernatants of umbilical cord Wharton's jelly as a conditioned medium (CM). First, WJ-MSCs were isolated, and their purity was analyzed. The immunophenotypes of WJ-MSCs were analyzed by flow cytometry. The quantitative expression of BCL2, BAX, and BAG1 in matured oocytes and embryos was evaluated through quantitative real-time polymerase chain reaction (qRT-PCR). Our findings showed that WJ-MSCs have a high proliferating capacity. The purity of the isolated cells was further validated by immunophenotyping, which revealed that their surface antigen expression had phenotypical properties similar to WJ-MSCs. When compared to CD34 and CD45 surface markers, the enlarged cells were positive for CD90, CD105, and CD44. There were significant differences in cytoplasmic maturation of oocytes and embryo quality between the two groups. The mRNA expression levels of BCL-2, BAG1, and BAX in matured oocytes and embryos were also significantly different between the two groups. Therefore, WJ-MSCs medium indicated potential efficacy in terms of ameliorating oocyte maturation and in promoting the development and genes expression of BAX, BCL-2, and BAG1.

Biomaterials and advanced technologies for the evaluation and treatment of ovarian aging

Ovarian aging is characterized by a progressive decline in ovarian function. With the increase in life expectancy worldwide, ovarian aging has gradually become a key health problem among women. Over the years, various strategies have been developed to preserve fertility in women, while there are currently no clinical treatments to delay ovarian aging. Recently, advances in biomaterials and technologies, such as three-dimensional (3D) printing and microfluidics for the encapsulation of follicles and nanoparticles as delivery systems for drugs, have shown potential to be translational strategies for ovarian aging. This review introduces the research progress on the mechanisms underlying ovarian aging, and summarizes the current state of biomaterials in the evaluation and treatment of ovarian aging, including safety, potential applications, future directions and difficulties in translation.

Single-cell multiomics analyses of spindle-transferred human embryos suggest a mostly normal embryonic development

Mitochondrial DNA (mtDNA) mutations are often associated with incurable diseases and lead to detectable pathogenic variants in 1 out of 200 babies. Uncoupling of the inheritance of mtDNA and the nuclear genome by spindle transfer (ST) can potentially prevent the transmission of mtDNA mutations from mother to offspring. However, no well-established studies have critically assessed the safety of this technique. Here, using single-cell triple omics sequencing method, we systematically analyzed the genome (copy number variation), DNA methylome, and transcriptome of ST and control blastocysts. The results showed that, compared to that in control embryos, the percentage of aneuploid cells in ST embryos did not significantly change. The epiblast, primitive endoderm, and trophectoderm (TE) of ST blastocysts presented RNA expression profiles that were comparable to those of control blastocysts. However, the DNA demethylation process in TE cells of ST blastocysts was slightly slower than that in the control blastocysts. Collectively, our results suggest that ST seems generally safe for embryonic development, with a relatively minor delay in the DNA demethylation process at the blastocyst stage.

Uncoupling of the inheritance of mtDNA and the nuclear genome by spindle transfer could prevent the transmission of mtDNA mutations. Systematic single-cell multiomic analyses of spindle transferred human embryos suggest this technique seems generally safe for human embryonic development and deserves further scientific evaluation and clinical testing.

Development and pregnancy rates of Camelus dromedarius-cloned embryos derived from in vivo- and in vitro-matured oocytes

Objective

The present study evaluated the efficiency of embryo development and pregnancy of somatic cell nuclear transfer (SCNT) embryos using different source-matured oocytes in Camelus dromedarius.

Methods

Camelus dromedarius embryos were produced by SCNT using in vivo- and in vitro- matured oocytes. In vitro embryo developmental capacity of reconstructed embryos was evaluated. To confirm the efficiency of pregnancy and live birth rates, a total of 72 blastocysts using in vitro- matured oocytes transferred into 45 surrogates and 95 blastocysts using in vivo- matured oocytes were transferred into 62 surrogates by transvaginal method.

Results

The collected oocytes derived from ovum pick up showed higher maturation potential into metaphase II oocytes than oocytes from the slaughterhouse. The competence of cleavage, and blastocyst were also significantly higher in in vivo- matured oocytes than in vitro- matured oocytes. After embryo transfer, 11 pregnant and 10 live births were confirmed in in vivo- matured oocytes group, and 2 pregnant and 1 live birth were confirmed in in vitro- matured oocytes group. Furthermore, blastocysts produced by in vivo-matured oocytes resulted in significantly higher early pregnancy and live birth rates than in vitro-matured oocytes.

Conclusion

In this study, SCNT embryos using in vivo- and in vitro-matured camel oocytes were successfully developed, and pregnancy was established in recipient camels. We also confirmed that in vivo-matured oocytes improved the development of embryos and the pregnancy capacity using the blastocyst embryo transfer method.

Perspectives on the development and future of oocyte IVM in clinical practice

Oocyte in vitro maturation (IVM) is an assisted reproductive technology designed to obtain mature oocytes following culture of immature cumulus-oocyte complexes collected from antral follicles. Although IVM has been practiced for decades and is no longer considered experimental, the uptake of IVM in clinical practice is currently limited. The purpose of this review is to ensure reproductive medicine professionals understand the appropriate use of IVM drawn from the best available evidence supporting its clinical potential and safety in selected patient groups. This group of scientists and fertility specialists, with expertise in IVM in the ART laboratory and/or clinic, explore here the development of IVM towards acquisition of a non-experimental status and, in addition, critically appraise the current and future role of IVM in human ART.

The effect of sodium selenite on apoptotic gene expression and development of in vitro cultured mouse oocytes in comparison with in vivo obtained oocytes

In vitro maturation (IVM) of oocytes is widely used in assisted reproduction technologies. The present study aimed to improve the in vitro oocyte maturation and its development through enriching the culture media with sodium selenite (SS). Moreover, the effects of SS on the expression of the oocytes apoptosis-related genes were assessed. In this study, male and female NMRI mice were used and after collecting their germinal vesicle (GV) oocytes, they were cultured with SS (experimental group) and without SS (control group). Collected metaphase II oocytes (MII) from the fallopian tube were considered as in vivo group. After in vitro culture, the oocytes were assessed in terms of nuclear maturation. The MII oocytes were inseminated and the development was examined until the blastocyst stage. Also, oocytes were subjected to the molecular analysis for evaluating the expression of BAX, BCL2, P53, and BAD genes using the real-time RT-PCR. The maturation rate was significantly increased in the SS supplemented group compared to the control one. The developmental rate of the embryos was significantly higher for both of the in vivo and SS supplemented groups rather than the control one, however, no significant difference was seen between these rates of the experimental and in vivo groups. Real-time RT-PCR did not show any significant differences in the expression of the apoptosis-related genes for all of the studied groups. The p53 gene was not expressed in any of groups. Sodium selenite improved the oocyte developmental competence but did not change the expression of the apoptosis-related genes in MII oocytes.

Urinary Organophosphate Metabolite Concentrations and Pregnancy Outcomes among Women Conceiving through in Vitro Fertilization in Shanghai, China

BACKGROUND

Animal studies suggest that pesticide exposure elicits endocrine changes, increases embryo implantation failure, and decreases litter size. However, only a few epidemiological studies have evaluated the effects of pesticides on the outcomes of in vitro fertilization (IVF) pregnancies.

OBJECTIVES

This study examined the associations between preconception organophosphate pesticides (OP) exposure and pregnancy outcomes among women undergoing IVF in a Chinese population.

METHODS

This study included 522 women with infertility who underwent IVF. Women were recruited from a prospective study, the China National Birth Cohort (CNBC), from Shanghai, China, between July 2017 and December 2018. Demographic and clinical information were collected from medical records and through questionnaires. Preconception exposure to OP was assessed by measuring six nonspecific dialkylphosphate (DAP) metabolites [diethylthiophosphate (DETP), diethylphosphate (DEP), diethyldithiophosphate (DEDTP), dimethylthiophosphate (DMTP), dimethylphosphate (DMP), dimethyldithiophosphate (DMDTP)] in urine samples collected at recruitment. Generalized estimating equation (GEE) models were used to evaluate the associations between OP and pregnancy outcomes.

RESULTS

Compared with women in the lowest quartile (Q1) of individual DEP and Σ4DAP (the sum of DMP, DMTP, DEP, and DETP), women in the highest quartile (Q4) had lower odds of successful implantation, clinical pregnancy, and live birth, and most of the negative trends were significant (p-trends<0.05). There were no significant associations between urinary DAP concentrations and early IVF outcomes, including total and mature oocyte counts, best embryo quality, fertilization, E2 trigger levels, and endometrial wall thickness.

CONCLUSION

Preconception OP exposure was inversely associated with successful implantation, clinical pregnancy, and live birth in women who underwent IVF. https://doi.org/10.1289/EHP7076.

The Effect of Human Chorionic Gonadotropin on the In vitro Development of Immature to Mature Human Oocytes: A Randomized Controlled Study

Context

In controlled ovarian hyperstimulation cycles, 15% of oocytes have been proven to be immature. Key factors include failure in signal transmission from the cumulus cell to the oocyte, insufficient level of luteinizing hormone, and internal conditions of the oocyte itself.

Aims

The aim of the present study was to investigate the effect of human chorionic gonadotropin (hCG) on the in vitro maturity of partially cumulus-denuded immature oocytes collected after controlled ovarian stimulation for in vitro fertilization (IVF).

Settings and Design

This was a prospective, randomized controlled design at the department of obstetrics and gynaecology, university hospital.

Subjects and Methods

Infertile women underwent gonadotropin-releasing hormone antagonist stimulated protocol for IVF with final maturation triggered by hCG, partially cumulus-denuded immature human oocytes were allocated to two groups: the first was treated with fertilization medium and the second was treated with fertilization medium and hCG. They were cultured for 24 h. Outcomes measured were the oocyte maturation rates to metaphase II (MII) and glucose-6-phosphate dehydrogenase (G6PD) activity of in vitro maturation (IVM) mature oocytes which represent the oocyte quality.

Statistical Analysis Used

The Mann-Whitney U-test and One-way ANOVA were used to compare continuous variables, and Chi-square was used for categorical data.

Results

In all, 250 immature stimulated oocytes were allocated (125 per group). The maturation rate was higher in the hCG supplement group (48% vs. 39.2%) without significance. The positive brilliant cresyl blue results among the MII oocytes developed from the metaphase I (MI) were significantly higher in the hCG group (P = 0.001).

Conclusions

Rescue IVM in fertilization culture medium plus hCG was slightly better than that in the only fertilization culture. MII oocytes developed from MI in hCG supplemented medium had a higher quality based on the measured G6PD activity.

Association between mild stimulated IVF/M cycle and early embryo arrest in sub fertile women with/without PCOS

BACKGROUND

The in vitro maturation (IVM) technique has physical and financial benefits, but a lower efficiency and outcome that is still unclear whether it is related to polycystic ovary syndrome (PCOS) itself or the IVM procedure. In this study, we analyzed the clinical and laboratory outcomes of an optimized IVM protocol in patients with and without PCOS. We also discussed the possible reasons for early embryo arrest in the IVM cycle.

METHODS

This prospective study involved 58 PCOS patients and 56 non-PCOS patients who underwent mild stimulated IVF combined IVM (IVF/M) cycles. The clinical and laboratory outcomes were compared between the two groups. Also, metaphase II (MII) oocytes were obtained after IVM from the two groups, and in vivo MII oocytes randomly collected from IVF patients were examined for mitochondrial function using a laser scanning confocal microscope (LSCM). The aneuploidy rate for arrested cleavage embryos from IVM and IVF oocytes were screened using Next Generation Sequencing (NGS).

RESULTS

Mildly stimulated IVF/M resulted in cumulative clinical pregnancy and implantation rates (40.2, 28.7% in the PCOS group vs. 41.9, 36% in the non-PCOS group), respectively. The blastocyst formation rates were comparable (28% vs. 28.2%) in PCOS and non-PCOS groups, respectively. Using LSCM, there was a significant decrease in the mitochondrial membrane potential of IVM oocytes compared with the control IVF oocytes (P < 0.001), but no significant difference between the PCOS and non-PCOS groups. The NGS showed that the aneuploidy rates were comparable (75, 75, and 66.6%) in IVM-PCOS, IVM-non-PCOS, and control IVF arrested embryos, respectively.

CONCLUSIONS

The mildly stimulated IVF/M protocol produced acceptable clinical outcomes in PCOS and non-PCOS patients. IVM itself rather than the PCOS condition adversely affected the embryo development through its effect on mitochondrial function, which appeared to be a possible cause for the embryo arrest in the IVM cycles rather than chromosomal aneuploidy.

5-Formylcytosine landscapes of human preimplantation embryos at single-cell resolution

Epigenetic dynamics, such as DNA methylation and chromatin accessibility, have been extensively explored in human preimplantation embryos. However, the active demethylation process during this crucial period remains largely unexplored. In this study, we use single-cell chemical-labeling-enabled C-to-T conversion sequencing (CLEVER-seq) to quantify the DNA 5-formylcytosine (5fC) levels of human preimplantation embryos. We find that 5-formylcytosine phosphate guanine (5fCpG) exhibits genomic element-specific distribution features and is enriched in L1 and endogenous retrovirus-K (ERVK), the subfamilies of repeat elements long interspersed nuclear elements (LINEs) and long terminal repeats (LTRs), respectively. Unlike in mice, paired pronuclei in the same zygote present variable difference of 5fCpG levels, although the male pronuclei experience stronger global demethylation. The nucleosome-occupied regions show a higher 5fCpG level compared with nucleosome-depleted ones, suggesting the role of 5fC in organizing nucleosome position. Collectively, our work offers a valuable resource for ten-eleven translocation protein family (TET)-dependent active demethylation-related study during human early embryonic development.

Effects of cyclic adenosine monophosphate modulators on maturation and quality of vitrified-warmed germinal vesicle stage mouse oocytes

BACKGROUND

It is still one of the unresolved issues if germinal vesicle stage (GV) oocytes can be successfully cryopreserved for fertility preservation and matured in vitro without damage after warming. Several studies have reported that the addition of cyclic adenosine monophosphate (cAMP) modulators to in vitro maturation (IVM) media improved the developmental potency of mature oocytes though vitrification itself provokes cAMP depletion. We evaluated whether the addition of cAMP modulators after GV oocytes retrieval before vitrification enhances maturation and developmental capability after warming of GV oocytes.

METHODS

Retrieved GV oocytes of mice were divided into cumulus-oocyte complexes (COCs) and denuded oocytes (DOs). Then, GV oocytes were cultured with or without dibutyryl-cAMP (dbcAMP, cAMP analog) and 3-isobutyl-l-methylxanthine (phosphodiesterase inhibitor) during the pre-vitrification period for 30 min.

RESULTS

One hour after warming, the ratio of oocytes that stayed in the intact GV stage was significantly higher in groups treated with cAMP modulators. After 18 h of IVM, the percentage of maturation was significantly higher in the COC group treated with dbcAMP. The expression of F-actin, which is involved in meiotic spindle migration and chromosomal translocation, is likewise increased in this group. However, there was no difference in chromosome and spindle organization integrity or developmental competence between the MII oocytes of all groups.

CONCLUSIONS

Increasing the intracellular cAMP level before vitrification of the GV oocytes maintained the cell cycle arrest, and this process may facilitate oocyte maturation after IVM by preventing cryodamage and synchronizing maturation between nuclear and cytoplasmic components. The role of cumulus cells seems to be essential for this mechanism.

Endothelin-1 promotes human germinal vesicle-stage oocyte maturation by downregulating connexin-26 expression in cumulus cells

STUDY QUESTION

Does endothelin-1 (ET-1) promote human oocyte maturation and by what mechanism?

SUMMARY ANSWER

Addition of ET-1 to the medium in which human germinal vesicle (GV)-stage immature oocytes are cultured enhances the GV breakdown (GVBD) rate; the resumption of meiosis may be initiated by ET-1 downregulating the expression of connexin-26 (Cx26) in cumulus cells via endothelin receptor type B (ETRB), leading to decreased cAMP levels in the oocyte.

WHAT IS KNOWN ALREADY

The paracrine factor ET-1 is secreted by ovarian somatic cells in pre-ovulatory follicles and regulates oocyte maturation in mice. Connexins, or gap junction proteins, form intercellular membrane channels that play important roles in the resumption of meiosis.

STUDY DESIGN, SIZE, DURATION

This laboratory study was conducted over a 1-year period. The effects of ET-1 on meiotic resumption were evaluated in human GV-stage cumulus-oocyte complexes (COCs; 70 oocytes/group). The transcriptome profiles of ET-1-treated or untreated cumulus cells were compared to explore the possible mechanisms by which ET-1 may regulate oocyte maturation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The ET-1, ETRA and ETRB expression levels in human cumulus cells from oocytes at different stages of maturation were evaluated using real-time quantitative PCR. Human GV-stage COCs collected from patients undergoing IVF at a university-affiliated infertility centre were cultured with or without ET-1, and cumulus cells were subsequently denuded using hyaluronidase and cultured in α-MEM. A GeneChip® Human Transcriptome Array was applied to explore differences in the whole-genome transcriptome profiles of cumulus cells treated with or without ET-1. Real-time quantitative PCR and Western blotting were used respectively to examine Cx26 mRNA and protein levels in cumulus cells. Changes in cAMP levels in both oocytes and cumulus cells after ET-1 treatment were measured using an enzyme-linked immunosorbent assay.

MAIN RESULTS AND THE ROLE OF CHANCE

Cumulus cells from MII-stage oocytes exhibited upregulated ET-1 expression, compared to those from GV-stage oocytes. The addition of ET-1 to the culture medium enhanced the GVBD rate of cumulus cell-enclosed human oocytes. Whole-genome transcriptome microarray analyses revealed significantly downregulated Cx26 expression in cumulus cells after ET-1 treatment, and this action was blocked by an ETRB antagonist. The involvement of Cx26 was further supported by the finding that ET-1 treatment led to decreased cAMP levels in oocytes but increased cAMP levels in cumulus cells.

LARGE SCALE DATA

Microarray data are published in the GEO database (GSE97684).

LIMITATIONS, REASONS FOR CAUTION

The heterogeneity of human COCs collected from patients undergoing IVF might affect the maturation results in vitro. Although we focused on the effects of ET-1 on human oocyte maturation in the present study, mammalian oocyte maturation is a complicated process involving many endocrine and paracrine factors.

WIDER IMPLICATIONS OF THE FINDINGS

Our present study suggests that in vitro, human GV-stage oocyte maturation could be enhanced by adding ET-1 to the culture medium. In the present study, we explored the molecular mechanisms by which ET-1 initiates the resumption of meiosis and demonstrated that ET-1 promotes oocyte maturation by downregulating the expression of the gap junction protein Cx26 in cumulus cells. These results expand our understanding of the molecular mechanisms underlying mammalian oocyte maturation and provide a basis for better in-vitro maturation strategies.

STUDY FUNDING AND COMPETING INTERESTS

This work was supported by grants from the China Natural Science Foundation (Grant Nos. 81170567 and 81370761). The authors declare that they have no conflicts of interest associated with this manuscript.

Comparison of GnRH agonist and hCG for priming in vitro maturation cycles in cancer patients undergoing urgent fertility preservation

In vitro maturation (IVM) of oocytes retrieved at germinal vesicle or Metaphase I stage, followed by vitrification of Metaphase II (MII) oocytes, has recently emerged as an option for urgent fertility preservation (FP). Priming is usually achieved with an injection of hCG, 10,000 IU, 36 hours before retrieval. This study aimed to assess a new method of priming, using GnRH agonists, and compare it to hCG, in cancer patients undergoing urgent FP. From 2009 to 2015, 373 cancer patients underwent MII oocyte cryopreservation after IVM cycles primed either with GnRHa (triptorelin 0.2 mg) (n = 138) or hCG (10,000 IU) (n = 235). Patients’ characteristics were comparable between the two groups. The number of COC retrieved was significantly higher in the GnRHa group (9.1 ± 6.8 versus 7.7 ± 5.5 oocytes, p = 0.04). However, the maturation rates (59 ±25% versus 64 ±26%, p = 0.07, respectively), and the total number of MII oocytes frozen (5.2 ±4.2 versus 4.9 ±4.0, p = 0.6, respectively) were similar between the GnRha and hCG groups. We did not find any difference between GnRHa and hCG priming for IVM. GnRHa priming is more physiological since it stimulates endogenous FSH and LH activity, and is well suited for FP in hormone-sensitive cancers and urgent cases.

Cilostamide affects in a concentration and exposure time-dependent manner the viability and the kinetics of in vitro maturation of caprine and bovine oocytes

This study investigated: 1) the kinetics of oocyte chromatin configuration during in vitro maturation (IVM) of caprine and bovine oocytes; and 2) the effect of in vitro pre-maturation (IVPM) with cilostamide with or without association of the follicular wall (FW) on the same parameters. In experiment I, cumulus-oocyte complexes (COCs) were cultured in vitro in a standard maturation medium for 6, 12, 18 or 30 h. For experiment II, the COCs were cultured for 30 h, either in a standard IVM medium or in IVPM containing cilostamide (10 or 20 μM) and FW alone or in combination, for 6 or 12 h before the onset of maturation. The MII rate was similar (P > .05) between 18 and 30 h of maturation, both of which were higher (P < .05) than 6 and 12 h IVM in both species (Experiment I). Contrary to caprine, all IVPM treatments presented a higher (P < .05) percentage of bovine oocytes arrested at the GV stage than the control treatment after 6 h of culture. The percentage of MII oocytes after 30 h (IVPM+IVM) of culture in bovine oocytes treated with 10 μM cilostamide associated with FW and FW alone cultured for 6 h presented MII percentages similar to the control. However, in caprine, these treatments significantly reduced the percentages of MII in relation to the control treatment (Experiment II). In conclusion, the combination of concentration-exposure time to cilostamide during IVPM delayed meiotic progression in bovine after 6 and 12 h of culture. However, overall the culture period (IVPM+IVM) influenced the oocyte chromatin configuration and kinetics in both species.

Formation and activation induction of primordial follicles using granulosa and cumulus cells conditioned media

Fertility preservation of prepubertal girls subjected to invasive cancer therapy necessitates defining protocols for activation of isolated primordial follicles. Granulosa (GCs) and cumulus cells (CCs) play pivotal role in oocyte development. Although GCs and CCs share some similarities, they differ in growth factors production. The current study was conducted to evaluate the effects of GCs, CCs and their conditioned media on mice primordial follicles activation. One-day-old mice ovaries were subjected to 6-day culture with base medium (BM), GC conditioned medium (GCCM), GC coculture (GCCC), CC conditioned medium (CCCM) or CC coculture (CCCC). Follicular growth and primordial to primary follicle transition was observed during 6-day culture, and follicular activation rate tended to be greater in GCCM than other groups (0.05 <P < 0.10). On Day 6, the expression of phosphatase and tensin homolog (PTEN) in GCCM group was lower than that in BM group (P = 0.020), the expression of phosphoinositide-3-kinase was higher in CCCC group than BM, GCCM and CCCM groups (P < 0.05), and the expression of connexin 37 was greater in the CCCM group as compared with BM, GCCC, and CCCC groups (P < 0.01). In conclusion, the current study showed that condition medium of GCs could enhance in vitro activation of primordial follicles, probably through downregulation of PTEN.

Single-cell DNA methylome sequencing of human preimplantation embryos

DNA methylation is a crucial layer of epigenetic regulation during mammalian embryonic development ^1-3 . Although the DNA methylome of early human embryos has been analyzed ^4-6 , some of the key features have not been addressed thus far. Here we performed single-cell DNA methylome sequencing for human preimplantation embryos and found that tens of thousands of genomic loci exhibited de novo DNA methylation. This finding indicates that genome-wide DNA methylation reprogramming during preimplantation development is a dynamic balance between strong global demethylation and drastic focused remethylation. Furthermore, demethylation of the paternal genome is much faster and thorough than that of the maternal genome. From the two-cell to the postimplantation stage, methylation of the paternal genome is consistently lower than that of the maternal genome. We also show that the genetic lineage of early blastomeres can be traced by DNA methylation analysis. Our work paves the way for deciphering the secrets of DNA methylation reprogramming in early human embryos.

Development of in vitro maturation techniques for clinical applications

In vitro maturation (IVM) refers to maturation in culture of immature oocytes at different stages that may or may not have been exposed to short courses of gonadotropins. The source of immature oocytes is an important feature for subsequent embryonic development, pregnancy, and healthy live births. IVM is an effective treatment that has already achieved significant outcomes of acceptable pregnancy and implantation rates and has led to the births of several thousand healthy babies. As the development of IVM treatment continues, an attractive possibility for improving the already successful outcome is to combine a natural-cycle in vitro fertilization (IVF) treatment with immature-oocyte retrieval followed by IVM of those immature oocytes. If the treatment processes can be simplified for immature-oocyte retrieval, different types of infertile women may be able to take advantage of these treatments. Mild-stimulation IVF combined with IVM treatment may represent a viable alternative to the standard treatment. Although IVM treatment is still considered to be experimental, it is now time to reconsider the IVM technology and its development. Mild-stimulation IVF combined with IVM may prove to be not just alternatives to standard treatments, but potentially first-line treatment choices.

Supplementation of cilostazol during in vitro maturation enhances the meiosis and developmental competence of yak oocytes by influencing cAMP content and mRNA expression

The efficiency of in vitro embryo production remains low compared with that observed in vivo. Recent studies have independently shown that cyclic adenosine monophosphate (cAMP) modulation prior to in vitro maturation (IVM) supplementation improves oocyte developmental competence. In this context, special cAMP modulators have been applied during IVM as promising alternatives to improve this biotechnology. Accordingly, this study was conducted to evaluate the effects of treatment with cilostazol, a PDE3 inhibitor, during pre-IVM culture on oocyte meiotic maturation in yak. Immature yak cumulus-oocyte complexes (COCs) were treated in vitro without (control) or with 5μM cilostazol for 0, 2, or 4h prior to IVM. Results showed that the presence of cilostazol in pre-IVM medium significantly increased the percentages of oocytes at metaphase II stage compared with that in the control groups (P<0.05). Moreover, pre-IVM with cilostazol significantly enhanced intraoocyte cAMP and glutathione (GSH) levels at the pre-IVM or IVM phase relative to the no pre-IVM groups (P<0.05). After in vitro fertilization (IVF) and parthenogenetic activation (PA), the developmental competences of oocytes and embryo quality were improved significantly after pre-IVM with cilostazol compared with the control groups (P<0.05), given that the cleavage and blastocyst formation rates and the total number of blastocyst cells were increased. The presence of cilostazol also increased the levels of mRNA expression for adenylate cyclase 3 (ADCY3) and protein kinase 1 (PKA1), as well as decreased the abundance of phosphodiesterase 3A (PDE3A) in COCs and IVF blastocysts, compared with their control counterparts (P<0.05). The results demonstrated that the meiotic progression of immature yak oocytes could be reversibly affected by cAMP modulators. By contrast, treatment with cilostazol during pre-IVM positively affected the developmental competence of yak oocytes, probably by improving intraoocyte cAMP and GSH levels and regulating mRNA expression patterns. We concluded that appropriate treatment with cilostazol during pre-IVM would be beneficial for oocyte maturation in vitro.

Outcomes of immature oocytes collected from ovarian tissue for cryopreservation in adult and prepubertal patients

The efficiency of oocyte in-vitro maturation (IVM) and vitrification procedures after ex-vivo collection from ovarian tissue were assessed according to patient age, number of retrieved oocytes and tissue transport conditions. The combined procedure was performed in 136 patients: 130 adults (mean 27.6 ± 5.6 years) and six prepubertal girls (mean 8.7 ± 2.3 years). A higher mean number of oocytes were collected in girls compared with adults (11.5 ± 8.0 versus 3.8 ± 4.2, respectively, P < 0.001) but the percentage of degenerated oocytes was significantly higher in girls (35.5% versus 17.1%, respectively, P < 0.001). IVM rates were significantly lower in prepubertal than postpubertal population (10.3% versus 28.1%, P = 0.002). In adults, a negative correlation was observed between number of retrieved oocytes and age (P = 0.002; r = -0.271); the correlation was positive between anti-Müllerian hormone (AMH) and number of collected oocytes (P = 0.002; r = 0.264). IVM rates were not correlated with AMH levels (r = 0.06) or age (r = -0.033). At present, nine oocytes and one embryo have been warmed in four patients and one biochemical pregnancy obtained. This suggests the combined procedure could be an additional option for fertility preservation.

Effect of Antioxidants (β-mercaptoethanol and Cysteamine) on Assisted Reproductive Technology In vitro

INTRODUCTION

Oocyte Culture of Germinal Vesicle (GV) and its growth improves Assisted Reproductive Technology (ART) invitro and infertility. Inappropriate culture medium environment, low quality of oocytes, increase in Oxidative Stress (OS) events, Reactive Oxygen Species (ROS) and free radicals production are the main factors that result in unsuccessful Invitro Maturation (IVM) and decrease in reproduction.

AIM

The present study was conducted with the aim to evaluate the effect of β-mercaptoethanol (BME) and Cysteamine (CYS) on IVM improvement, embryo fertilization and development of blastocyst of mouse immature oocyte.

MATERIALS AND METHODS

Oocytes were obtained from 4-6 weeks old Naval Medical Research Institute (NMRI) female mice, 48 hours after stimulation with Intraperitoneal (IP) injection of 10 IU Pregnant Mare Serum Gonadotropin (PMSG). GV oocyte with and without cumulus cells were isolated from ovaries and cultured in Tissue Culture Medium (TCM) 199 with availability of 100 μM of antioxidants (BME and CYS). After 24 hours, mature oocyte in metaphase II (MII) were fertilized with sperm in In vitro Fertilization (IVF) medium (T6) and evaluated for fetal development into blastocyst.

RESULTS

BME and CYS could significantly (p<0.05) increase the rate of IVM and oocyte evolution, and embryo formation in medium culture. Furthermore, it is demonstrated that existence of Cumulus Oocyte Complexes (COC) significantly showed better IVM, fertilization and evolution trend as compared to oocytes without cumulus cover or Denuded Oocytes (DO), especially in TCM199 plus BME and CYS. So that the change in GV stage oocytes to MII (maturation rate), fertilization rates or 2PN formation, and two cell embryos formation or blastocyst development rate in the treatment group with addition of BME & CYS and COC was statistically significant as compared to the DO group (p-value < 0.0001).

CONCLUSION

Both cellular and environmental factors could be important and involved in ART improvement.

Chapter 3 Current Challenges in Immature Oocyte Cryopreservation

Current freezing technology, especially the vitrification method, has markedly improved oocyte survival rate after warming, and the pregnancy rate is comparable to that achieved with fresh oocytes. However, most groups report using oocytes matured in vivo for vitrification. Although immature oocytes can be vitrified successfully, clinical outcomes do not reach that of vitrification of matured oocytes. The current literature suggests that oocytes should be vitrified at mature metaphase II (M-II) stage following IVM rather than at the immature germinal vesicle (GV) stage, because the potential for oocyte maturation is reduced when vitrification is performed on immature oocytes at the GV stage.

Strategies for Fertility Preservation in Female and Male Cancer Survivors

Improved survival rates and quality of life following modern cancer treatment have resulted in a growing number of patients requesting maintenance of reproductive capacity, both before and after completion of treatment. Several established options are currently available. In men, sperm banking should be offered as soon as the diagnosis of any malignant disease is established, irrespective of the expected cryosurvival rate. In such cases, conception can be achieved with frozen-thawed spermatozoa following either intrauterine insemination (IUI) or intracytoplasmic sperm injection (ICSI). In women, depending on the type of cancer, the presence of an adequate ovarian reserve, and time to delay cancer treatment, in vitro fertilization (IVF) with embryo cryopreservation constitutes a valid alternative. On the other hand, cryopreservation of mature oocytes following IVF/ICSI offers some advantages, but it is still limited by its low success rate. Emerging and exciting techniques of germ cell/gonadal tissue cryopreservation (banking) followed by autotransplantation have been clinically explored, particularly in women. Novel cryotechnologies of ovarian and testicular tissue have proven efficacious and new transplantation strategies promise improved results. However, only one live birth following autotransplanted frozen-thawed ovarian tissue has been established and there are still no pregnancies reported from autotransplanted cryopreserved testicular tissue in the human. Efficiency and safety of these techniques needs to be demonstrated. Methods for gamete in vitro maturation also need further development. Gonadal tissue cryopreservation and transplantation should be considered experimental in humans for the present time until greater evidence regarding efficacy and safety is accrued.

Experimental strategies towards increasing intracellular mitochondrial activity in oocytes: A systematic review

PURPOSE

The mitochondrial complement is critical in sustaining the earliest stages of life. To improve the Assisted Reproductive Technology (ART), current methods of interest were evaluated for increasing the activity and copy number of mitochondria in the oocyte cell.

METHODS

This covered the researches from 1966 to September 2015.

RESULTS

The results provided ten methods that can be studied individually or simultaneously.

CONCLUSION

Though the use of these techniques generated great concern about heteroplasmy observation in humans, it seems that with study on these suggested methods there is real hope for effective treatments of old oocyte or oocytes containing mitochondrial problems in the near future.

New Perspectives on Criteria for the Determination of HCG Trigger Timing in GnRH Antagonist Cycles

The aim of this study was to investigate 2 quantification criteria to evaluate the developmental condition of follicles cohort and clarify their impacts upon the determining of human chorionic gonadotropin trigger timing and the reproductive outcome: the proportion of mature follicles in growing follicles cohort on the day of human chorionic gonadotropin trigger and the peak estradiol level per oocyte on the day of human chorionic gonadotropin administration.Of the patients who underwent in vitro fertilization/ intracytoplasmic sperm injection-embryo transfer from 2011 to 2013, 492 controlled ovarian hyperstimulation cycles using gonadotropin-releasing hormone antagonists reaching the ovum pick-up and fresh embryo-transfer stage were included. Patients were divided into 3 groups according to their ≥17 mm/≥10 mm follicles ratio on the day of human chorionic gonadotropin administration (Low proportion: ≤30%, Middle proportion: 30%-60%, High proportion: ≥60%). Patients were divided into 5 groups according to their peak estradiol level/oocyte (Group A: <100 pg/mL per oocyte, Group B: 100-199 pg/mL per oocyte, Group C: 200-299 pg/mL per oocyte, Group D: 300-399 pg/mL per oocyte, Group E ≥400 pg/mL per oocyte) as well. Comparison among groups was made regarding ovarian stimulation characteristics, fertilization rate, good quality embryo rate, implantation, pregnancy, and live birth rates.On the basis of ≥17 mm/≥10 mm follicles ratio, the number of oocyte retrieved in low proportion group is more than other 2 groups. Implantation rate, clinical pregnancy, and live birth rate in high proportion group were 25.8%, 42.7%, and 31.1%, respectively, which is highest in 3 groups, and statistical significance existed between high and middle proportion groups. When the division is based on peak estradiol level/oocyte, the number of oocyte retrieved of ≥400 pg/mL per oocyte Group was significantly lowest compared with the other 4 groups. Matured ovum rate, fertilization rate, and good quality embryos rate exhibited an increasing trend as the peak estradiol level/oocyte increased. While pregnancy rate, implantation rate, and live birth rate were found to be lower whenever estradiol/oocyte ratio exceeded 400 pg/mL per oocyte or less than 100 pg/mL per oocyte, and there is statistical difference.Patients with the proportion of mature follicle reaching 60% on the day of human chorionic gonadotropin trigger and peak estradiol/oocyte level within 100∼399 pg/mL range can get a better pregnancy and implantation rate.

Rescue in vitro maturation (IVM) of immature oocytes in stimulated cycles in women with low functional ovarian reserve (LFOR)

Rescue in vitro maturation (IVM) is currently not a routine procedure in association with in vitro fertilization (IVF). We compared in a prospectively cohort study of 10 patients with normal functional ovarian reserve (NFOR) and of 25 with low functional ovarian reserve (LFOR), defined by abnormally high FSH and/or abnormally low AMH levels), IVM dynamics of immature oocytes. Following controlled ovarian hyperstimulation in IVF cycles, only immature oocytes underwent rescue IVM (for up to 48 h). Oocyte maturation dynamics, fertilization rates, embryo development, and pregnancy rates were then compared between NFOR and LFOR patients. Though proportion of MI and GV oocytes reaching MII stages within 48 h and rate of maturation of MI oocytes did not differ, in women with LFOR significantly more GV oocytes reached MII stage within 24 h (30.4 vs. 66.9 %; P = 0.013), while fertilization rates and embryo generation numbers were similar between both groups. Rescue IVM, thus, produced 1.5 additional embryos for transfer in women with LFOR and 1.6 in patients with NFOR, a highly significant difference in relative improvement in available embryo numbers for LFOR (+60.0 %) and NFOR women (+16.5 %). Rescue IVM, thus, not only demonstrates different time dynamics between women with LFOR and NFOR but also disproportionate efficacy in improving available embryo numbers for transfer in favor of LFOR patients. 1/7 patients, who reached embryo transfer with only embryos produced via rescue IVF conceived and delivered, proving that rescue IVF in women with LFOR also improves pregnancy and delivery chances. Because of the small number of embryos LFOR patients produce, every additional embryo is of considerable potential clinical significance for them, suggesting that rescue IVM in women with LFOR should become routine practice.

A novel follicle-stimulating hormone receptor mutation causing primary ovarian failure: a fertility application of whole exome sequencing

STUDY QUESTION

Can whole exome sequencing (WES) and in vitro validation studies be used to find the causative genetic etiology in a patient with primary ovarian failure and infertility?

SUMMARY ANSWER

A novel follicle-stimulating hormone receptor (FSHR) mutation was found by WES and shown, via in vitro flow cytometry studies, to affect membrane trafficking.

WHAT IS KNOWN ALREADY

WES may diagnose up to 25-35% of patients with suspected disorders of sex development (DSD). FSHR mutations are an extremely rare cause of 46, XX gonadal dysgenesis with primary amenorrhea due to hypergonadotropic ovarian failure.

STUDY DESIGN, SIZE, DURATION

A WES study was followed by flow cytometry studies of mutant protein function.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study subjects were two Turkish sisters with hypergonadotropic primary amenorrhea, their parents and two unaffected sisters. The affected siblings and both parents were sequenced (trio-WES). Transient transfection of HEK 293T cells was performed with a vector containing wild-type FSHR as well as the novel FSHR variant that was discovered by WES. Cellular localization of FSHR protein as well as FSH-stimulated cyclic AMP (cAMP) production was evaluated using flow cytometry.

MAIN RESULTS AND THE ROLE OF CHANCE

Both affected sisters were homozygous for a previously unreported missense mutation (c.1222G>T, p.Asp408Tyr) in the second transmembrane domain of FSHR. Modeling predicted disrupted secondary structure. Flow cytometry demonstrated an average of 48% reduction in cell-surface signal detection (P < 0.01). The mean fluorescent signal for cAMP (second messenger of FSHR), stimulated by FSH, was reduced by 50% in the mutant-transfected cells (P < 0.01).

LIMITATIONS, REASONS FOR CAUTION

This is an in vitro validation. All novel purported genetic variants can be clinically reported only as 'variants of uncertain significance' until more patients with a similar phenotype are discovered with the same variant.

WIDER IMPLICATIONS OF THE FINDINGS

We report the first WES-discovered FSHR mutation, validated by quantitative flow cytometry. WES is a valuable tool for diagnosis of rare genetic diseases, and flow cytometry allows for quantitative characterization of purported variants. WES-assisted diagnosis allows for treatments aimed at the underlying molecular etiology of disease. Future studies should focus on pharmacological and assisted reproductive treatments aimed at the disrupted FSHR, so that patients with FSH resistance can be treated by personalized medicine.

STUDY FUNDING/COMPETING INTERESTS

E.V. is partially funded by the DSD Translational Research Network (NICHD 1R01HD068138). M.S.B. is funded by the Neuroendocrinology, Sex Differences and Reproduction training grant (NICHD 5T32HD007228). The authors have no competing interests to disclose.

Cyclic AMP-elevating Agents Promote Cumulus Cell Survival and Hyaluronan Matrix Stability, Thereby Prolonging the Time of Mouse Oocyte Fertilizability

Cumulus cells sustain the development and fertilization of the mammalian oocyte. These cells are retained around the oocyte by a hyaluronan-rich extracellular matrix synthesized before ovulation, a process called cumulus cell-oocyte complex (COC) expansion. Hyaluronan release and dispersion of the cumulus cells progressively occur after ovulation, paralleling the decline of oocyte fertilization. We show here that, in mice, postovulatory changes of matrix are temporally correlated to cumulus cell death. Cumulus cell apoptosis and matrix disassembly also occurred in ovulated COCs cultured in vitro. COCs expanded in vitro with FSH or EGF underwent the same changes, whereas those expanded with 8-bromo-adenosine-3',5'-cyclic monophosphate (8-Br-cAMP) maintained integrity for a longer time. It is noteworthy that 8-Br-cAMP treatment was also effective on ovulated COCs cultured in vitro, prolonging the vitality of the cumulus cells and the stability of the matrix from a few hours to >2 days. Stimulation of endogenous adenylate cyclase with forskolin or inhibition of phosphodiesterase with rolipram produced similar effects. The treatment with selective cAMP analogues suggests that the effects of cAMP elevation are exerted through an EPAC-independent, PKA type II-dependent signaling pathway, probably acting at the post-transcriptional level. Finally, overnight culture of ovulated COCs with 8-Br-cAMP significantly counteracted the decrease of fertilization rate, doubling the number of fertilized oocytes compared with control conditions. In conclusion, these studies suggest that cAMP-elevating agents prevent cumulus cell senescence and allow them to continue to exert beneficial effects on oocyte and sperm, thereby extending in vitro the time frame of oocyte fertilizability.

Developmental Competence of Vitrified-Warmed Bovine Oocytes at the Germinal-Vesicle Stage is Improved by Cyclic Adenosine Monophosphate Modulators during In Vitro Maturation

Cryopreservation of mature oocytes and embryos has provided numerous benefits in reproductive medicine. Although successful cryopreservation of germinal-vesicle stage (GV) oocytes holds promise for further advances in reproductive biology and clinical embryology fields, reports regarding cryopreservation of immature oocytes are limited. Oocyte survival and maturation rates have improved since vitrification is being performed at the GV stage, but the subsequent developmental competence of GV oocytes is still low. The purpose of this study was to evaluate the effects of supplementation of the maturation medium with cyclic adenosine monophosphate (cAMP) modulators on the developmental competence of vitrified-warmed GV bovine oocytes. GV oocytes were vitrified-warmed and cultured to allow for oocyte maturation, and then parthenogenetically activated or fertilized in vitro. Our results indicate that addition of a cAMP modulator forskolin (FSK) or 3-isobutyl-1-methylxanthine (IBMX) to the maturation medium significantly improved the developmental competence of vitrified-warmed GV oocytes. We also demonstrated that vitrification of GV oocytes led to a decline in cAMP levels and maturation-promoting factor (MPF) activity in the oocytes during the initial and final phases of maturation, respectively. Nevertheless, the addition of FSK or IBMX to the maturation medium significantly elevated cAMP levels and MPF activity during IVM. Taken together, our results suggest that the cryopreservation-associated meiotic and developmental abnormalities observed in GV oocytes may be ameliorated by an artificial increase in cAMP levels during maturation culture after warming.

Chromosomal aberrations in in-vitro matured oocytes influence implantation and ongoing pregnancy rates in a mouse model undergoing intracytoplasmic sperm injection

Implantation failure and early pregnancy loss have been reported to be closely related to the quality of mammalian oocytes; however, the pregnant outcome of embryos from in-vitro matured (IVM) oocytes remains unknown. In this study we examined spindle assembly and chromosome segregation during differentiation, and the duration of IVM of mouse oocytes. The resulting implantation and pregnancy outcomes were analyzed to clarify the relationship between the spindle and chromosomes of IVM oocytes and implantation and early pregnancy. Cumulus-enclosed germinal vesicle oocytes were collected and randomly cultured in IVM medium with different IVM durations. One part of IVM oocytes were analyzed the spindle and chromosome morphology by immunofluorescence method, and the other part of them were fertilized by intracytoplasmic sperm injection. The resulting embryos were transferred into pseudo-pregnant female mice, and the post-implantation and full term development was observed. The chromosome aberrations and incorrect spindle assembly seems not affect the early development and blastocyst cell number derived from IVM oocytes, however the development potential of the resulting embryos after implantation were significant decreased with the ratio increasing of chromosome aberrations and incorrect spindle assembly. Accordingly, the full-term development was also decreased. In conclusion, the present study showed the spindle assembly of in vitro-matured oocytes was one of the most important factors that affected the implantation and ongoing pregnancy rates of IVM oocytes, and the improvement by an appropriate duration of maturation in vitro will enhance the post-implantation development potential of the resulting embryos, and decrease implantation failure and early pregnancy loss.

Live birth of twins after performing early hCG administration as a modification of natural cycle in vitro fertilization, in a women with decreased ovarian reserve

PURPOSE

This case reports the first twin live births achieved in a woman with a serum FSH of such magnitude -80 IU/L, after following early hCG administration in natural cycle in vitro fertilization (IVF).

METHOD

Case report.

RESULTS

A 27-year-old with 2 years of primary infertility presented with regular menses since menarche. FSH following clomiphene citrate challenge test was 80 IU/L. Antral follicle count was 1. After failing two IVF cycles, natural cycle IVF with early hCG administration was attempted. Ovulation with 10,000 IU hCG was triggered when the dominant follicle was 10 mm in mean diameter. Two smaller follicles were also present. Oocyte collection was performed 38 h after hCG injection. Three mature oocytes were retrieved. Two oocytes fertilized normally. Two good-quality embryos were transferred on day 2. Bichorionic biamniotic pregnancy was achieved and healthy twins were delivered at term.

CONCLUSIONS

This case suggests that natural cycles with early hCG administration should be investigated further as an option for poor responders to retrieve more than one mature oocyte, and prevent premature ovulation. We believe this case to represent the patient with the highest serum FSH level, reflective of ovarian reserve at the time of treatment, to achieve a live birth. It is also the first case report to describe this modification on the traditional natural cycle.

In vitro maturation of immature human oocytes for clinical application

Meiotic progression in the oocyte is defined as oocyte maturation from reinitiation of the first meiotic division from the germinal vesicle (GV) stage to the metaphase-II (M-II) stage (Fig. 1), (Cha and Chian, Hum Reprod Update 4:103-120, 1998). Priming with FSH or HCG prior to immature oocyte retrieval improves oocyte maturation and pregnancy rates. The size of follicles may be an important feature for IVM treatment. The combination of natural-cycle IVF with immature oocyte retrieval followed by IVM is an attractive treatment for young women with all types of infertility without recourse to ovarian stimulation with an acceptable pregnancy rate.

Addition of lysophosphatidic acid to mouse oocyte maturation media can enhance fertilization and developmental competence

STUDY QUESTION

Does exposure to lysophosphatidic acid (LPA) during in vitro maturation (IVM) enhance the maturation and developmental competence of mouse oocytes?

SUMMARY ANSWER

Supplementation of IVM medium with 30 μM LPA enhanced the developmental competence of in vitro matured oocytes and so made them more comparable to in vivo matured control oocytes.

WHAT IS KNOWN ALREADY

LPA is a small phospholipid that acts as an extracellular signaling molecule by binding to and activating at least five G protein-coupled receptors. LPA has various biological actions, with both developmental and physiological effects.

STUDY DESIGN, SIZE, DURATION

During IVM, LPA at six different doses (0, 1, 10, 30, 50 or 100 μM) was added into the TCM-199 medium. After maturation, the developmental competence and other parameters of the oocytes were assessed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Immature GV stage oocytes from 5- to 6-week-old female BDF-1 mice were incubated for 17-18 h in IVM medium containing 0, 1, 10 or 30 μM LPA and then either fertilized in vitro with epididymal sperm, or assessed for spindle morphology, mitochondrial membrane potential (ΔΨm) or the mRNA expression of a meiotic checkpoint gene (Mad2), a microtubule structure gene (Hook1), two maternally derived genes (Mater and Hsf1) and an apoptosis-related gene (Caspase6). The fertilized embryos were grown in vitro to assess blastocyst-formation rates, differential cell counts and apoptosis.

MAIN RESULTS AND THE ROLE OF CHANCE

Rates of maturation, fertilization and blastocyst formation and hatching were significantly higher in the 30 μM LPA-supplemented group (94.3, 96.3, 79.1 and 51.3%, respectively) than in the unsupplemented control (0 μM) group (80.5, 87.5, 61.3 and 37.8%, respectively) and more comparable to that of the in vivo matured oocytes (100, 96.5, 95.3 and 92.9%, respectively). LPA did not adversely affect mitochondrial activity, spindle integrity, blastocyst cell number, caspase positivity or Mad2 expression. Oocytes matured in 30 μM LPA had reduced Caspase6 expression, but Hook1, Mater and Hsf1 were up-regulated in all of the LPA-supplemented groups.

LIMITATIONS, REASONS FOR CAUTION

Chromosomal aneuploidy in the resultant blastocysts and the production of normal pups were not assessed. Only mouse oocytes were assessed.

WIDER IMPLICATIONS OF THE FINDINGS

Supplementation of IVM medium with 30 μM LPA may enhance the developmental competence of mouse oocytes without affecting apoptosis, spindle normalcy or mitochondrial integrity.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by a research grant (02-2012-021) from the Seoul National University Bundang Hospital. The authors declare that they have no competing interests.

Somatic cells regulate maternal mRNA translation and developmental competence of mouse oocytes

Germ cells divide and differentiate in a unique local microenvironment under the control of somatic cells. Signals released in this niche instruct oocyte reentry into the meiotic cell cycle. Once initiated, the progression through meiosis and the associated programme of maternal messenger RNA translation are thought to be cell autonomous. Here we show that translation of a subset of maternal mRNAs critical for embryo development is under the control of somatic cell inputs. Translation of specific maternal transcripts increases in oocytes cultured in association with somatic cells and is sensitive to EGF-like growth factors that act only on the somatic compartment. In mice deficient in amphiregulin, decreased fecundity and oocyte developmental competence is associated with defective translation of a subset of maternal mRNAs. These somatic cell signals that affect translation require activation of the PI(3)K-AKT-mTOR pathway. Thus, mRNA translation depends on somatic cell cues that are essential to reprogramme the oocyte for embryo development.

The transcriptome of follicular cells: biological insights and clinical implications for the treatment of infertility

BACKGROUND

Oocyte maturation is under strict regulatory control, not only from intrinsic cellular processes, but also extrinsic influences. While the oocyte is directly connected to the surrounding cumulus cells (CCs) via a network of gap junctions facilitating communication and exchange of molecules, it is also influenced by the greater follicular environment. In order to produce an oocyte capable of successfully transmitting the female genetic material and able to support the earliest stages of preimplantation development, cytoplasmic and nuclear maturation must be achieved. Granulosa and CCs play an essential role in the maturation and competence acquisition of the developing oocyte. The fact that these cells are closely associated with the oocyte, share the same microenvironment and can be easily collected during IVF procedures makes them attractive targets for basic research and the development of clinically relevant assays. Analysis of follicular cells is likely to reveal important information concerning the viability and genetic constitution of their associated oocyte, as well as increase our understanding of normal follicular processes and the impact of disorders or of medical interventions such as controlled ovarian stimulation (COS). This review summarizes results obtained during the investigation of granulosa and CCs, and considers the possibilities of using follicular cells as surrogate markers of stimulation response during IVF, oocyte/embryo competence and clinical outcome.

METHODS

In order to summarize the current knowledge obtained from the analysis of follicular cells, a thorough literature search was carried out. Relevant research articles published in English up to March 2013 were reviewed.

RESULTS

Multiple groups of genes expressed in follicular cells have been identified as possible indicators of ovulation, oocyte maturity, fertilization, chromosome status, ability to generate embryos capable of reaching the blastocyst stage of development, embryo morphology and the establishment of a pregnancy. However, there is a general lack of uniformity concerning groups of gene biomarkers among different studies.

CONCLUSIONS

Extensive investigation of genes and proteins of granulosa and CCs has provided a detailed insight into the follicular microenvironment surrounding oocytes. It was evident from the data reviewed that the gene expression of follicular cells influences and is influenced by the oocyte, affecting factors such as maturity, chromosomal constitution, viability and competence. However, a general lack of overlap among genes identified as potentially useful biomarkers suggests that the transcriptome of follicular cells could be affected by multiple intrinsic factors, having to do with the patient and possibly the aetiology of infertility, as well as extrinsic factors, such as hormonal stimulation. Further work is required in order to establish a universally applicable, non-invasive test for the determination of oocyte competence based upon follicular cell assessment.

Morphological and molecular markers are correlated with maturation-competence of human oocytes

STUDY QUESTION

Does the position of the germinal vesicle (GV) in human oocytes correlate with molecular and morphological parameters as well as with maturation-competence?

SUMMARY ANSWER

The position of GV in human oocytes correlates with density of microtubule (MT) filaments, concentration of Fyn, nucleolus localization and the ability of the oocytes to complete maturation following GV breakdown (GVBD).

WHAT IS KNOWN ALREADY

Our knowledge is confined to oocytes of young mice where maturation-competence is correlated with a central GV and regulated by MTs and the presence of a chromatin ring. Fyn kinase is localized at the spindle and cortex of mouse oocytes and plays a role in both maturation and MT stabilization.

STUDY DESIGN, SIZE, DURATION

Spatial localization of the GV and nucleolus (central or peripheral), the presence of a chromatin ring, the localization of Fyn, MT density and oocyte maturation were assessed in 153 human oocytes, 335 oocytes from young mice (2-month-old) and 146 oocytes from old mice (12-month-old).

PARTICIPANTS/MATERIALS, SETTING, METHODS

GV human oocytes were donated by consenting female patients (n = 57), 21-45-year-old undergoing IVF/ICSI. As a control, GV mouse oocytes were collected from female mice after injection of pregnant mares' serum gonadotrophin. Human and mouse GV oocytes allocated for immunocytochemistry were fixed on day of retrieval, stained with specific antibodies and imaged using a confocal laser-scanning microscope. Human and mouse oocytes allocated for maturation were incubated for 48 and 24 h, respectively. GVBD and extrusion of the first polar body (PBI) were assessed using differential interference contrast optics.

MAIN RESULTS AND THE ROLE OF CHANCE

GV location was peripheral and independent of age in 69.9% of the human oocytes, but GV location did vary with age in mice oocytes; it was central in 89.9% of the oocytes retrieved from young-mice and peripheral in 52.1% of the oocytes retrieved from old mice (P < 0.05). A central GV, whether in human or mouse oocytes, was highly correlated with a central nucleolus, absence of Fyn at the GV and a dense MT network (P < 0.05), whereas a peripheral GV correlated with peripheral nucleolus, presence of Fyn at the GV and a flimsy MT network. After 48 h in culture, no degeneration was observed in human central-GV oocytes, however, 12/95 (12.6%) of the peripheral-GV oocytes degenerated (P < 0.05). No correlation was observed between GV position and presence of a chromatin ring. The percentage of human oocytes that extruded the PBI after completing GVBD was significantly higher (73.7%) in central than in peripheral-GV oocytes (45.8%; P < 0.05). In mice oocytes, central location of the GV correlated with maturation competence in young (P < 0.05) but not old mice.

LIMITATIONS, REASONS FOR CAUTION

The fact that the human GV oocytes used in this study were exposed to gonadotrophic stimulation but failed to mature in vivo might be a sign of their low quality and this should be considered when drawing conclusions from the data. Furthermore, our observation that only peripheral-GV human oocytes were degraded may indicate that they are of a lower quality than central-GV human oocytes.

WIDER IMPLICATIONS OF THE FINDINGS

We suggest that the central location of GV within the oocytes, which is associated with an absence of Fyn at the GV and the presence of thick filamentous MTs in the ooplasm, may serve as a predictor of successful maturation and provide new insights for the use of IVM.

Supplementation with low concentrations of melatonin improves nuclear maturation of human oocytes in vitro

PURPOSE

Studies in bovine and porcine have indicated that melatonin (MT) could induce meiotic maturation of immature oocytes in vitro. The object of the current study was to investigate if MT could ameliorate human oocytes maturation during rescue in vitro maturation (IVM).

METHODS

Two hundred seventy eight germinal vesicle (GV) oocytes and 451 (MI) metaphase I oocytes were vitrified, thawed and then matured in vitro. All the oocytes were randomly allocated into six groups in which the oocytes were cultured in medium supplemented with different concentrations of MT (0, 10(-2), 1, 10(2), 10(4), 10(6) nM) and nuclear maturation was evaluated at 6 h, 12 h, 18 h, 24 h and 48 h of culture.

RESULTS

The optimal MT concentration for both GV and MI oocytes was 1 nM. At 24 h of culture, nuclear maturation rate of MI oocytes cultured in 1 nM MT medium was significantly higher than other groups (P < 0.05); Nuclear maturation rate of GV oocytes cultured in 1 nM MT medium was also significantly higher than the control group (P < 0.05). On the other hand, decreased nuclear maturation rate was observed in the high MT concentration group (10(6) nM).

CONCLUSIONS

The current study demonstrated that low concentration of exogenous MT could ameliorate nuclear maturation of human oocyte during rescue IVM, while high concentration of MT presented negative effects.

Thinking big by thinking small: application of microfluidic technology to improve ART

In Vitro Fertilization (IVF) laboratories often carry a penchant to resist change while in the pursuit of maintaining consistency in laboratory conditions. However, implementation of new technology is often critical to expand scientific discoveries and to improve upon prior successes to advance the field. Microfluidic platforms represent a technology that has the potential to revolutionize the fundamental processes of IVF. While the focus of microfluidic application in IVF has centered on embryo culture, the innovative platforms carry tremendous potential to improve other procedural steps and represents a possible paradigm shift in how we handle gametes and embryos. The following review will highlight application of various microfluidic platforms in IVF for use in maturation, manipulation, culture, cryopreservation and non-invasive quality assessment; pointing out new insights gained into functions of sperm, oocytes and embryos. Platform design and function will also be discussed, focusing on limitations, advancements and future refinements that can further aid in their clinical implementation.

Fertilization, embryo development, and clinical outcome of immature oocytes obtained from natural cycle in vitro fertilization

PURPOSE

To analyze the fertilization, embryo development, and clinical outcome of immature oocytes obtained from natural cycle IVF in women with regular cycles.

METHODS

Natural cycle IVF was performed in 28 patients who had normal ovaries, > 6 antral follicle counts and were less than 40 years old (n=28 cycles). An hCG trigger of 10,000 IU was administered 36 h before oocyte collection when the diameter of the dominant follicle (DF) was over 12 mm. Oocytes were retrieved from DF as well as from the cohort of smaller follicles. Embryological aspects of the mature and immature oocytes retrieved from these cycles as well as the implantation and clinical pregnancy rates depending on the origin of the embryos transferred were evaluated.

RESULT(S)

Overall clinical pregnancy and implantation rates were 20.8 % and 6.7 %, respectively. There were no differences in in vitro maturation (IVM), fertilization and embryo development between immature oocytes retrieved with and without in vivo matured oocytes. However, the clinical and implantation rates in cycles with embryos produced from in vivo matured oocytes transferred were better than the cycles where only IVM embryos were transferred (30.8 %, 9.1 % vs. 9.1 %, 3.2 %).

CONCLUSION(S)

Although our results show that immature oocytes from natural cycle IVF can fertilize normally and can be used to increase the number of embryos available for transfer, the embryos derived from the immature oocytes in natural cycles IVF have a poorer reproductive potential.

Female fertility loss and preservation: threats and opportunities

BACKGROUND

Ovarian aging and cytotoxic treatments are the most common causes for fertility loss in women. With increasing numbers of young female survivors following cytotoxic cancer treatments, the issue of fertility preservation has assumed greater importance.

METHODS

We review the literature on the causes of female fertility loss as well as the recent advances in fertility preservation options and strategies that might be of interest to oncologists. Currently, several methods and techniques exist for fertility preservation of female patients with cancer including embryo freezing, ovarian protection techniques, oocyte cryopreservation, ovarian tissue cryopreservation followed by autotransplantation, and recently in vitro culture of ovarian tissue, follicles, and oocytes. Each method or technique has advantages and disadvantages related to current success rate, required delay in cancer treatment, sperm requirement, and risk of reintroducing cancer cells.

RESULTS

To date, embryo freezing is the only established method successfully and widely used for fertility preservation of female patients with cancer. The other methods are promising but still considered experimental.

CONCLUSION

Patient awareness, physician knowledge, early counseling, costs management, international registry, interdisciplinary networks, and research development are necessary to improve the current care in the field of female fertility preservation.

In-vitro maturation of human oocytes: before or after vitrification?

PURPOSE

This study aims to determine if in-vitro maturation (IVM) of human immature oocytes should be performed before or after vitrification.

METHODS

A total of 184 immature oocytes were randomly divided into two different groups: 100 were vitrified at metaphase II (MII) stage 24 h-48 h after IVM (group 1) and 84 were immediately vitrified at germinal vesicle (GV) or metaphase I (MI) stages and in vitro matured after warming (group 2).

RESULTS

Survival rate after warming was similar in both groups (86.9% versus 84.5%). However, oocyte maturation rate per collected oocyte was significantly higher for oocytes matured before vitrification (group 1, 46%) than for oocytes vitrified before IVM (group 2, 23.8%) (p < 0.01). Consequently, the number of MII oocytes inseminated per oocyte collected was significantly higher for group 1 (40%) than for group 2 (23.8%) (p < 0.05).

CONCLUSION

IVM procedure is more efficient when it is performed before oocyte vitrification.