IVM of human immature oocytes for infertility treatment and fertility preservation.

Background: Thousands of healthy babies are born from in vitro maturation (IVM) procedures, but the rate of efficiency differs with the source of immature oocytes obtained. Recently, there are different IVM protocols proposed for infertility treatment and fertility preservation. Methods: Based on the literature, the clinical application for IVM of immature oocytes was summarized. Main findings Results: Immature oocytes may be retrieved from women after priming with or without the use of follicular stimulation hormone (FSH), human chorionic gonadotrophin (hCG) or a combination of both FSH and hCG. Successful pregnancy rates with IVM technology seem to be correlated with the number of immature oocytes obtained. With the source and culture course of immature oocytes, there are various IVM protocols. IVM of immature oocytes is profoundly affected by the culture conditions, but no breakthrough has been made by improving the IVM medium itself. Thus, the clinical application of IVM technology continues to evolve. Conclusion: IVM technology is a useful technique for infertile women and fertility preservation. Mild stimulation IVF combined with IVM of immature oocytes is a viable alternative to the conventional stimulation IVF cycle treatment as it may prove to be an optimal first-line treatment approach.

The case for mild stimulation for IVF: recommendations from The International Society for Mild Approaches in Assisted Reproduction.

The practice of ovarian stimulation for IVF is undergoing a fundamental re-evaluation as recent data begin to successfully challenge the traditional paradigm that ovarian stimulation should be aimed at the retrieval of as many oocytes as possible, in the belief that this will increase pregnancy rates. An opposing view is that live birth rate should not be the only end-point in evaluating the success of IVF treatment and that equal emphasis should be placed on safety and affordability. The International Society for Mild Approaches in Assisted Reproduction (ISMAAR) committee has carried out an up-to-date literature search, with the evidence being graded according to the University of Oxford's Centre for Evidence-Based Medicine. The recommendations were formulated taking into account the quality of evidence on the efficacy, risk and cost of each intervention. ISMAAR recommends adopting a mild approach to ovarian stimulation in all clinical settings as an increasing body of evidence suggests that mild stimulation is as effective as conventional stimulation, while being safer and less expensive. Mild ovarian stimulation could replace conventional stimulation, thus making IVF safer and more accessible worldwide.

Role of pyroglutamic acid in cumulus cells of women with polycystic ovary syndrome.

PURPOSE: Polycystic ovary syndrome is a complex heterogeneous endocrine disorder associated with established metabolic abnormalities and is a common cause of infertility in females. Glutathione metabolism in the cumulus cells (CCs) of women with PCOS may be correlated to the quality of oocytes for infertility treatment; therefore, we used a metabolomics approach to examine changes in CCs from women with PCOS and oocyte quality. METHODS: Among 135 women undergoing fertility treatment in the present study, there were 43 women with PCOS and 92 without. CCs were collected from the two groups and levels of pyroglutamic acid were measured using LC-MS/MS followed by qPCR and Western blot analysis to examine genes and proteins involved in pyroglutamic acid metabolism related to glutathione synthesis. RESULTS: Women with PCOS showed increased levels of L-pyroglutamic acid, L-glutamate, and L-phenylalanine and decreased levels of Cys-Gly and N-acetyl-L-methionine. Gene expression of OPLAH, involved in pyroglutamic synthesis, was significantly increased in women with PCOS compared with those without. Gene expression of GSS was significantly decreased in women with PCOS and synthesis of glutathione synthetase protein was decreased. Expression of nuclear factor erythroid 2-related factor 2, involved in resistance to oxidative stress, was significantly increased in women with PCOS. CONCLUSIONS: CCs of women with PCOS showed high concentrations of pyroglutamic acid and reduced glutathione synthesis, which causes oxidative stress in CCs, suggesting that decreased glutathione synthesis due to high levels of pyroglutamic acid in CCs may be related to the quality of oocytes in women with PCOS.

Chromosome aneuploidy analysis in embryos derived from in vivo and in vitro matured human oocytes.

BACKGROUND: In vitro oocyte maturation (IVM) is being increasingly approached in assisted reproductive technology (ART). This study aimed to evaluate the quality of embryos generated by in-vitro matured immature follicles, as a guideline for further clinical decision-making. METHODS: A total of 52 couples with normal karyotypes underwent in vitro fertilization, and 162 embryos were donated for genetic screening. Embryos in IVF group were generated by mature follicles retrieved during gonadotrophin-stimulated in vitro fertilization (IVF) cycles. And embryos in IVM group were fertilized from IVM immature oocytes. RESULTS: The average age of the women was 30.50 ± 4.55 years (range 21-42 years) with 87 embryos from IVF group and 75 embryos from IVM group. The rate of aneuploid with 28 of the 87 (32.2%) embryos from IVF group and 21 of the 75 (28%) embryos from IVM group, with no significant difference. The frequency of aneuploid embryos was lowest in the youngest age and increased gradually with women's age, whether in IVF group or IVM group and risen significantly over 35 years old. The embryos with morphological grade 1 have the lowest aneuploidy frequency (16.6%), and increase by the grade, especially in IVF group. In grade 3, embryos in IVM group were more likely to be euploid than IVF group (60% vs 40%, respectively). CONCLUSIONS: IVM does not affect the quality of embryos and does not increase the aneuploidy rate of embryos. It is clinically recommended that women more than 35 years have a high aneuploidy rate and recommended to test by PGS (strongly recommended to screened by PGS for women more than 40 years). Women aged less than 35 years old for PGS according to their physical and economic conditions. Embryo with poor quality is also recommended to test by PGS, especially for grade III embryos.

The effect of lysophosphatidic acid-supplemented culture medium on human immature oocytes matured in vitro.

BACKGROUND: Lysophosphatidic acid-supplemented culture medium significantly increases the oocyte maturation rate in vitro. However, potential targets and pathways involved remain unknown. METHODS: A total of 43 women, who underwent cesarean section and aged between 18 and 35 years with good health, were included in this study. Immature oocytes were obtained and cultured with 10 µM lysophosphatidic acid. After culture, oocyte maturation was assessed and oocytes and cumulus cells were collected for RNA sequencing. Hierarchical indexing for spliced alignment of transcripts 2 method was used to align clean reads to the human genome. The featureCounts and edgeR package were used to calculate gene expression and analyze differences between groups respectively. ClusterProfiler program was used to perform Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis. RESULTS: Oocyte maturation rate increased significantly following 48 h culture with lysophosphatidic acid. In cumulus cells, Gene Ontology analysis revealed the top 20 items enriched by upregulated genes and downregulated genes respectively; Kyoto Encyclopedia of Genes and Genomes analysis showed that upregulated genes in the treatment group were enriched in TNF signaling and insulin secretion pathways and downregulated genes were enriched in TNF signaling and cell adhesion molecules. In oocytes, Gene Ontology analysis revealed the top 20 items enriched by upregulated genes and downregulated genes respectively; Kyoto Encyclopedia of Genes and Genomes analysis showed that upregulated genes in the treatment group were enriched in MAPK signaling, gap junction, and cell cycle pathways and downregulated genes were enriched in MAPK signaling, estrogen signaling, RAP1 signaling, and gap junction pathways. CONCLUSIONS: Lysophosphatidic acid in culture medium enhances human oocyte maturation in vitro and the identified some potential pathways may associate with oocyte maturation.

Single-cell multiomic analysis of in vivo and in vitro matured human oocytes.

STUDY QUESTION: Are there any differences between in vivo (IVV) and in vitro (IVT) matured metaphase II (MII) oocytes at the molecular level? SUMMARY ANSWER: Between IVV and IVT oocytes, 507 differentially expressed genes (DEGs) were identified; the non-CpG methylomes were significantly different, but the CpG methylomes and genomic copy number variations (CNVs) were similar. WHAT IS KNOWN ALREADY: A previous study using microarray and single-cell RNA-seq analysis revealed that numerous genes were differentially expressed between IVV and IVT oocytes. Independent studies of DNA methylation profiling in human oocytes have revealed negative correlations between gene transcription and the DNA methylation level at gene promoter regions. No study has compared global CpG or non-CpG methylation between these two groups of oocytes. Although a high level of aneuploidy has been reported in MII oocytes, no direct comparison of IVV and IVT oocytes based on single-cell sequencing data has been performed. STUDY DESIGN, SIZE, DURATION: We collected eight IVV oocytes from six patients and seven IVT oocytes from seven patients and then analysed each oocyte using the previously established single-cell triple omics sequencing (scTrioseq) analysis to determine associations among the transcriptome, DNA methylome and chromosome ploidy in the oocytes. PARTICIPANTS/MATERIALS, SETTING, METHODS: All IVV oocytes were donated by patients who received 150 IU gonadotropin per day from the third day of their menstrual cycle, followed by GnRH antagonist after 5 days of gonadotropin stimulation. All IVT oocytes were from immature oocytes which were donated by volunteers undergoing delivery by caesarean section then cultured in oocyte maturation medium containing 75 mIU/ml hMG for 24 to 48 h. Every single oocyte was analysed using the previously established single-cell multiomic sequencing analysis. MAIN RESULTS AND THE ROLE OF CHANCE: There were 507 genes differentially expressed between the IVV (n = 8) and IVT (n = 7) oocytes, even though their global transcriptome profiles were similar. The enriched genes in IVV oocytes were related to the cell cycle process while those in IVT oocytes were related to mitochondrial respiration biogenesis. Although the global CpG methylation of the two groups of oocytes was similar, the non-CpG methylation level in IVV oocytes was higher than that in IVT oocytes. A high aneuploidy ratio was found in both groups, but the aneuploidy did not affect transcription according to the correlation analysis. LARGE-SCALE DATA: N/A. LIMITATIONS AND REASONS FOR CAUTION: Due to the difficulty in collecting MII oocytes, especially IVV matured oocytes, the sample size was limited. WIDER IMPLICATIONS OF THE FINDINGS: Our findings indicate that single-cell multiomic sequencing can be utilised to examine the similarity and differences between IVV and IVT matured MII oocytes. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the Ministry of Science and Technology of China, National Key R&D Program of China (No. 2017YFC1001601). The donated oocytes were collected by Shanghai Tenth People's Hospital. The authors declare no competing interests.

Genomic expression profiles in cumulus cells derived from germinal vesicle and MII mouse oocytes.

Cumulus cells (CCs) are distinct from other granulosa cells and the mutual communication between CCs and oocytes is essential for the establishment of oocyte competence. In the present study we assessed genomic expression profiles in mouse CCs before and after oocyte maturation in vitro. Microarray analysis revealed significant changes in gene expression in CCs between the germinal vesicle (GV) and metaphase II (MII) stages, with 2615 upregulated and 2808 downregulated genes. Genes related to epidermal growth factor, extracellular matrix (Ptgs2, Ereg, Tnfaip6 and Efemp1), mitochondrial metabolism (Fdx1 and Aifm2), gap junctions and the cell cycle (Gja1, Gja4, Ccnd2, Ccna2 and Ccnb2) were highlighted as being differentially expressed between the two development stages. Real-time polymerase chain reaction confirmed the validity and reproducibility of the results for the selected differentially expressed genes. Similar expression patterns were identified by western blot analysis for some functional proteins, including EFEMP1, FDX1, GJA1 and CCND2, followed by immunofluorescence localisation. These genes may be potential biomarkers for oocyte developmental competence following fertilisation and will be investigated further in future studies.

Effects of GnRH antagonist on endometrial protein profiles in the window of implantation.

GnRH antagonists can suppress luteinizing hormone and follicle-stimulating hormone (FSH), with less initial stimulatory effect and lower risk of ovarian hyperstimulation syndrome. The effects of GnRH antagonists on embryonic implantation remain controversial. To evaluate the effects of GnRH antagonists, endometrial tissues were biopsied from 12 women with intracytoplasmic sperm injection treatment, in which four subjects undergoing controlled ovulation stimulation with rFSH and GnRH antagonist, four subjects with a GnRH agonist long protocol, and four natural cycle controls. After iTRAQ quantification analysis, 24 proteins showed differential expression between natural cycle and agonist treatment group and 39 proteins between natural cycle and antagonist treatment group. A total of seven proteins demonstrated differential expression only in antagonist treatment group. Bioinformatic analysis implied these proteins can function in cell processes including angiogenesis, cell proliferation, apoptosis, cell migration, and immune response. Furthermore, GnRH antagonist suppressed the function of GNAS and ANPEP, which were important for endometrial functions. Immunohistochemical staining showed that ANPEP was mainly localized in the human endometrial stroma, while ACO2, CDC5L, and GNAS were mainly localized in the glands. This study could provide insights into the effect of GnRH antagonists on the endometrium, and help optimize the embryo implantation and improve the success rate for GnRH antagonist protocol.

Oocyte vitrification: advances, progress and future goals.

BACKGROUND: Recent advances in vitrification technology have markedly improved the efficacy of oocyte cryopreservation in terms of oocyte survival and pregnancy, as well as live birth rates. However, there still remains room for improvement in terms of vitrification techniques. OBJECTIVE: The remaining challenges include the development of a less cytotoxic vitrification solution and of a safe vitrification device in order to have vitrification techniques considered as a standard clinical laboratory procedure. METHODS: A systematic electronic literature search strategy has been conducted using PubMed (Medline) databases with the use of the following key words: oocyte, vitrification, cryoprotectant, preservation, pregnancy, and live birth. A list of published papers focused on the improvement of vitrification techniques to have the vitrification protocol standardized have been evaluated in full text for this review. Only key references were cited. CONCLUSIONS: Vitrification technology has made significant advancements and holds great promise, but many issues remains to be addressed before it becomes a standardized procedure in clinical laboratories such as the fact that oocyte vitrification may not require a high concentration of cryoprotectant in the vitrification solution when it has a suitable cooling and warming rate. There is also no consistent evidence that indicates the absence of risk to the vitrified oocytes when they are stored for a prolonged period of time in direct-contact with liquid nitrogen. The long-term development of infants born as a result of this technology equally remains to be evaluated.

The effect of minimal concentration of ethylene glycol (EG) combined with polyvinylpyrrolidone (PVP) on mouse oocyte survival and subsequent embryonic development following vitrification.

PURPOSE: Vitrification techniques employ a relatively high concentration of cryoprotectant in vitrification solutions. Exposure of oocytes to high concentrations of cryoprotectant is known to damage the oocytes via both cytotoxic and osmotic effects. Therefore, the key to successful vitrification of oocytes is to strike a balance between the usage of minimal concentration of cryoprotectant without compromising their cryoprotective actions. METHODS: The minimal concentration of ethylene glycol (EG) on mouse oocyte survival and subsequent embryonic development was evaluated following vitrification-warming and parthenogenetic activation. Polyvinylpyrrolidone (PVP) combined with EG on mouse oocyte survival and subsequent embryonic development as well as morphology of the spindle and chromosome alignment were also evaluated. Vitrification system was adapted with JY Straw and the cooling rate was approximately 442-500 °C/min. In contrast, the warming rate was approximately 2,210-2,652 °C/min. RESULTS: Survival rate of oocytes increased significantly when 15 % EG was combined with 2 % PVP in vitrification solution (VS). The effect of combination of EG and PVP was not significant when the concentration of EG was 20 % and higher. Although there were no significant differences in embryonic development, the percentage of abnormal spindle and chromosome alignment was significantly higher in the oocytes without 2 % PVP in VS. CONCLUSIONS: Our data provide a proof of principle for oocyte vitrification that may not require a high concentration of cryoprotectant. There are synergic effects of EG combined with PVP for oocyte vitrification, which may provide important information to the field in developing less cytotoxic VS.

[Retracted] MicroRNA­202 inhibits endometrial stromal cell migration and invasion by suppressing the K­Ras/Raf1/MEK/ERK signaling pathway.

Following the publication of this paper, it was drawn to the Editor's attention by a concerned reader that certain of the Transwell invasion assay data shown in Figs. 2C and 4B were strikingly similar to data appearing in different form in a paper by different authors at a different research institute that had already been submitted for publication. Owing to the fact that the contentious data in the above article had already been submitted for publication prior to its submission to International Journal of Molecular Medicine, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a satisfactory reply. The Editor apologizes to the readership for any inconvenience caused. [International Journal of Molecular Medicine 46: 2078­2088, 2020; DOI: 10.3892/ijmm.2020.4749].

Expression of G protein estrogen receptor (GPER) on membrane of mouse oocytes during maturation.

PURPOSE: To determine expression of G-protein estrogen receptor (GPER) in mouse oocyte membrane during maturation. METHODS: The expression of GPER from different maturation stages of oocytes, in vivo and in vitro matured oocytes as well as aging oocytes was examined by immune-fluorescence GPR30 antibody and the images were analyzed by laser scanning confocal microscope. Further confirmation was performed by Western blots for cell fractionation. RESULTS: Significant fluorescent signal was observed on the surface of mouse oocytes. The image expression was lower in germinal vesicle (GV) stage than mature metaphase-II (M-II) stage oocytes. There was high expression in in-vivo matured oocytes compared to in vitro matured oocytes. The highest expression was observed in aging oocytes compared with other oocytes. CONCLUSIONS: The changes of expression of GPER on mouse oocytes plasma membrane confirm oocyte membrane maturation, suggesting that those changes of GPER may be related to the functional role of oocyte maturation.

Effects of different sperm sources on the clinical outcomes of in vitro oocyte maturation cycles combined with intracytoplasmic sperm injection.

Objectives: To evaluate the embryonic developments and clinical outcomes of different sperm sources with cycles of intracytoplasmic sperm injection (ICSI) and in vitro maturation (IVM). Methods: This retrospective study was approved by the hospital ethics committee and conducted in the hospital in vitro fertilization (IVF) clinic. From January 2005 to December 2018, 239 infertile couples underwent IVM-ICSI cycles and were divided into three groups according to different sperm sources. Group 1 comprised patients with percutaneous epididymal sperm aspiration (PESA; n = 62, 62 cycles), group 2 comprised patients with testicular sperm aspiration (TESA; n = 51, 51 cycles), and group 3 comprised patients with ejaculated sperm (n = 126, 126 cycles). We calculated the following outcomes: 1) outcomes per IVM-ICSI cycle: fertilization rate, cleavage rate, and embryo quality; 2) outcomes per embryo transfer cycle: endometrial thickness, implantation rate, biochemical pregnancy rate, clinical pregnancy rate, and live birth rate. Results: There was no difference in basic characteristics among the three groups, such as the female partner's age, basal follicle-stimulating hormone (FSH), basal luteinizing hormone (LH), and antral follicle count (p > 0.1). There were no statistically significant differences according to the IVM-ICSI cycle among the three groups in fertilization rate, cleavage rate, and rate of good-quality embryos (p > 0.05). The results were similar among cycles regarding the number of transfer embryos and endometrial thickness per embryo transfer cycle among the three groups (p > 0.05). There were also similar clinical outcomes per embryo transfer cycle among the three groups, such as the biochemical pregnancy rate, clinical pregnancy rate, and live birth rate (p > 0.05). Conclusions: Different sperm sources, percutaneous epididymal sperm aspiration, testicular sperm aspiration, and ejaculated sperm, do not affect the embryo and clinical outcomes after IVM-ICSI cycles.

Oocyte vitrification technology has made egg-sharing donation easier in China.

When infertile women undergoing IVF or intracytoplasmic sperm injection (ICSI) have more than 20 mature oocytes retrieved, at least 15 oocytes are inseminated by their husband's spermatozoa. The extra oocytes are cryopreserved by vitrification. If the patients became pregnant and have healthy live births, the patients are encouraged to donate their remaining cryopreserved oocytes. Forty-seven egg-sharing donors were recruited after having normal deliveries and they donated their remaining oocytes, totalling 395 cryopreserved oocytes, to 75 recipients. The survival rate of vitrified-warmed oocytes was 83.0%. Following insemination by ICSI, the fertilization and cleavage rates were 83.8% and 89.8%, respectively. Out of 75 recipients, 71 recipients completed the treatment cycles and 30 of them became pregnant with clinical pregnancy and implantation rates of 42.3% and 25.5%, respectively. The birthweight of the new-born infants (22 from singleton and two from one set of twins) were 3344.5 ± 669.1g and 2425.0 ± 742.5 g, respectively. No birth defects were observed for the live births. These results indicate that oocyte vitrification is an effective methodology for an egg-sharing donation programme, with acceptable pregnancy and implantation rates.

Effect of culture medium volume and embryo density on early mouse embryonic development: tracking the development of the individual embryo.

PURPOSE: To determine the optimal volume or density of embryos for the well-of-the-well (WOW) system in order to track the development of individual embryos and to determine whether the WOW system can reverse the negative impact of culturing embryos singly. METHODS: (1) Mouse embryos (groups of nine at the 2-cell stage) were cultured in 6.25 µl, 12.50 µl, 25.00 µl and 50.00 µl of droplets of culture medium under paraffin oil; (2) Groups of three, six, nine and twelve embryos at the 2-cell stage were cultured in 50 µl of droplet of culture medium under paraffin oil; (3) Groups of nine embryos at the 2-cell stage were cultured in 50 µl of droplet under paraffin oil with or without nine micro-wells made on the bottom of the Petri dish into each of which were placed one of the nine embryos (WOW system). Also single 2-cell stage embryos was cultured individually in 5.5 µl of droplet of culture medium under paraffin oil with or without a single micro-well made on the bottom of the Petri dish (WOW system for single culture). At the end of culture, the percentages of blastocyst development, hatching and hatched blastocysts were compared in each group. The blastocysts were fixed for differential staining. RESULTS: The blastocyst development was significantly higher (P < 0.05) when nine embryos were cultured in 50 µl of droplet of culture medium compared with other volumes. The blastocyst development was significantly reduced (P < 0.05) in single embryo culture compared to group embryo culture with or without the WOW system. The blastocyst development was not improved when single embryo cultured individually in a micro-well was compared to single embryo cultured individually without micro-well. The total cell numbers of blastocysts were significantly higher in group embryo culture than single embryo culture regardless of whether the WOW system was used. In addition, the total cell numbers of blastocysts were significantly higher (P < 0.05) in single embryo culture with the WOW system than without. CONCLUSIONS: Group embryo culture is superior to single embryo culture for blastocyst development. The WOW system with 50 µl of droplet of culture medium can be used to track the individual development of embryo cultured in groups while preserving good embryonic development. The reduced embryonic development with single embryo culture cannot be ameliorated by the WOW system.

Effect of dominant follicle status at the time of retrieval on the clinical outcomes in natural cycle IVF combined with immature oocyte treatment.

OBJECTIVE: It is commonly believed that the oocytes from small follicles are unhealthy when a dominant follicle (DF) is recruited in the ovaries, especially when the DF is ovulated. This study aims to confirm whether the presence or ovulation of DF at the time of retrieval affects the clinical outcome of the natural cycle IVF with in vitro maturation (NC-IVF/M) treatment. METHODS: Data were collected from 446 women with regular menstrual cycle and 536 retrieval cycles using NC-IVF/M treatment. The cycles were divided into three groups based on the results of the oocyte retrieval cycle. Group A covers the collection of oocytes from the DF and small follicles; Group B incorporates failed oocyte retrieval from DF and then the oocytes are retrieved only from small follicles; and Group C includes the retrieval of oocytes only from small follicles accompanied with an ovulated DF. Furthermore, Group B and C have subgroups to include whether in vivo matured oocytes were obtained from small follicles. Following aspiration of DF and small follicles, mature oocytes were inseminated on the date of retrieval by intracytoplasmic sperm injection (ICSI) and the immature oocytes were matured in vitro. If the immature oocytes were matured in vitro, they were inseminated using ICSI, and then the embryos obtained from in vivo and in vitro matured oocytes were transferred accordingly. RESULTS: The oocytes from DF were successfully retrieved in 445 cycles (83.0%), failed to be retrieved in 54 cycles (10.1%) and ovulated in 37 cycles (6.9%). In Group A, an average of 2.0 ± 1.7 mature oocytes were retrieved, which was significantly higher than the average of Group B, with 1.3 ± 1.3 matured oocytes and Group C, with an average of 1.1 ± 1.5 matured oocytes (P < 0.01). However, the average number of immature oocytes retrieved from each group show no difference among the three groups. There was no significant difference in maturation rates of immature oocytes, fertilization rates among the three groups. The clinical pregnancy rate per transfer cycle is 34.5%, 34.6% and 25.7% in Group A, B and C, respectively. No significant differences were observed in embryonic development and implantation capacity in Group B and C in comparison to Group A. And there was no significant difference in clinical pregnancy, implantation, live birth and miscarriage rates among the three groups. No significant differences were observed in the developmental and implantation capacity according to with or without in vivo matured oocytes were retrieved in Group B and Group C. CONCLUSION: The presence or ovulation of the dominant follicle from the ovaries does not significantly influence the developmental and implantation capacity of immature oocytes retrieved from small follicles, suggesting that NC-IVF/M is a promising treatment option for women without ovarian stimulation.

Changes in the Mitochondria-Related Nuclear Gene Expression Profile during Human Oocyte Maturation by the IVM Technique.

To address which mitochondria-related nuclear differentially expressed genes (DEGs) and related pathways are altered during human oocyte maturation, single-cell analysis was performed in three oocyte states: in vivo matured (M-IVO), in vitro matured (M-IVT), and failed to mature in vitro (IM-IVT). There were 691 DEGs and 16 mitochondria-related DEGs in the comparison of M-IVT vs. IM-IVT oocytes, and 2281 DEGs and 160 mitochondria-related DEGs in the comparison of M-IVT vs. M-IVO oocytes, respectively. The GO and KEGG analyses showed that most of them were involved in pathways such as oxidative phosphorylation, pyruvate metabolism, peroxisome, and amino acid metabolism, i.e., valine, leucine, isoleucine, glycine, serine, and threonine metabolism or degradation. During the progress of oocyte maturation, the metabolic pathway, which derives the main source of ATP, shifted from glucose metabolism to pyruvate and fatty acid oxidation in order to maintain a low level of damaging reactive oxygen species (ROS) production. Although the immature oocytes could be cultured to a mature stage by an in vitro technique (IVM), there were still some differences in mitochondria-related regulations, which showed that the mitochondria were regulated by nuclear genes to compensate for their developmental needs. Meanwhile, the results indicated that the current IVM culture medium should be optimized to compensate for the special need for further development according to this disclosure, as it was a latent strategy to improve the effectiveness of the IVM procedure.

The Differential Metabolomes in Cumulus and Mural Granulosa Cells from Human Preovulatory Follicles.

This study evaluated the differences in metabolites between cumulus cells (CCs) and mural granulosa cells (MGCs) from human preovulatory follicles to understand the mechanism of oocyte maturation involving CCs and MGCs. CCs and MGCs were collected from women who were undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatment. The differences in morphology were determined by immunofluorescence. The metabolomics of CCs and MGCs was measured by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) followed by quantitative polymerase chain reaction (qPCR) and western blot analysis to further confirm the genes and proteins involved in oocyte maturation. CCs and MGCs were cultured for 48 h in vitro, and the medium was collected for detection of hormone levels. There were minor morphological differences between CCs and MGCs. LC-MS/MS analysis showed that there were differences in 101 metabolites between CCs and MGCs: 7 metabolites were upregulated in CCs, and 94 metabolites were upregulated in MGCs. The metabolites related to cholesterol transport and estradiol production were enriched in CCs, while metabolites related to antiapoptosis were enriched in MGCs. The expression of genes and proteins involved in cholesterol transport (ABCA1, LDLR, and SCARB1) and estradiol production (SULT2B1 and CYP19A1) was significantly higher in CCs, and the expression of genes and proteins involved in antiapoptosis (CRLS1, LPCAT3, and PLA2G4A) was significantly higher in MGCs. The level of estrogen in CCs was significantly higher than that in MGCs, while the progesterone level showed no significant differences. There are differences between the metabolomes of CCs and MGCs. These differences may be involved in the regulation of oocyte maturation.

Dysregulated sphingolipid metabolism and autophagy in granulosa cells of women with endometriosis.

We evaluated metabolic profiles between cumulus cells (CCs) and mural granulosa cells (MGCs) derived from women with endometriosis to identify their correlations with oocyte quality. CCs and MGCs were collected from women with and without endometriosis undergoing in vitro fertilization/intracytoplasmic sperm injection treatment. The metabolomics of CCs and MGCs were measured by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) followed by a quantitative polymerase chain reaction to further confirm the genes involved in the metabolic results. LC-MS/MS analysis revealed differences in 24 metabolites of CCs and 71 metabolites of MGCs between groups. Among them, five metabolites were upregulated and 19 metabolites were downregulated in CCs with endometriosis, whereas three metabolites were upregulated and 68 metabolites were downregulated in MGCs with endometriosis. Metabolites related to sphingolipid metabolism, which included palmitic acid (PA) and docosahexaenoic acid, increased significantly only in CCs with endometriosis, whereas sphingosine and PA were significantly downregulated in MGCs with endometriosis compared with CCs and MGCs without endometriosis. Gene expression involved in ceramide synthesis (CERS1, SPTL1, and SMPD1) and autophagy (BECN1, LAMP, and PC3) were significantly higher in CCs with endometriosis according to FASN, BECN1, and LAMP protein expressions. However, gene expression involved in ceramide synthesis (SPHK1, ASAH1, and SGPP1) and autophagy (BECN1, LAMP, and PC3) were significantly lower in MGCs with endometriosis, whereas CERS1 and UGCG expression increased. There are differences in sphingolipid metabolites in CCs and MGCs with endometriosis compared with women without endometriosis. These differences seem to be involved in the regulation of autophagic cell death in preovulatory follicles.

Mice lacking the USP2 deubiquitinating enzyme have severe male subfertility associated with defects in fertilization and sperm motility.

The ubiquitin-proteasome system plays an important role in spermatogenesis. However, the functions of deubiquitinating enzymes in this process remain poorly characterized. We previously showed that the deubiquitinating enzyme USP2 is induced in late elongating spermatids. To identify its function, we generated mice lacking USP2. Usp2 -/- mice appeared normal, and the weights of major organs, including the testis, did not differ from wild type (Usp2 +/+). However, although the numbers of testicular spermatids and epididymal spermatozoa were normal in Usp2 -/- males, these animals had a severe defect in fertility, yielding only 12% as many offspring as Usp2 +/+ littermates. Spermatogenesis in Usp2 -/- mice was morphologically normal except for the presence of abnormal aggregations of elongating spermatids and formation of multinucleated cells in some tubules. The epididymal epithelium was morphologically normal in Usp2 -/- mice, but some abnormal cells other than sperm were present in the lumen. Usp2 -/- epididymal spermatozoa manifested normal motility when incubated in culture media, but rapidly became immotile when incubated in PBS in contrast to Usp2 +/+ spermatozoa, which largely maintained motility under this condition. Usp2 -/- and +/+ spermatozoa underwent acrosome reactions in vitro with similar frequency. In vitro fertilization assays demonstrated a severe defect in the ability of Usp2 -/- spermatozoa to fertilize eggs. This could be bypassed by intracytoplasmic sperm injection or removal of the zona pellucida, which resulted in fertilization rates similar to that of Usp2 +/+ mice. We demonstrate for the first time, using mouse transgenic approaches, a role for the ubiquitin system in fertilization.