In vitro maturation of oocytes in light of ovarian mitochondrial improvement: effectiveness and safety.

In vitro maturation of oocytes (IVM) represents an assisted reproductive technique that involves the minimal or absence of ovarian stimulation and is beneficial to specific groups of patients. These may include women with polycystic ovarian syndrome and/or patients who need a fertility preservation option before undergoing gonadotoxic treatment. However, when IVM is applied in cases where it is not recommended, it can be considered as an add-on technique, as described by the ESHRE Guideline Group on Female Fertility Preservation. Interestingly, IVM has not been proven yet to be as effective as conventional IVF in the laboratory, in terms of clinical pregnancy and live birth rates, while concerns have been raised for its long-term safety. As a result, both safety and efficacy of IVM remain still questionable and additional data are needed to draw conclusions.

Application of amphiregulin in IVM culture of immature human oocytes and pre-insemination culture for COCs in IVF cycles.

Background: Amphiregulin (AR) is a growth factor that resembles the epidermal growth factor (EGF) and serves various functions in different cells. However, no systematic studies or reports on the role of AR in human oocytes have currently been performed or reported. This study aimed to explore the role of AR in human immature oocytes during in vitro maturation (IVM) and in vitro fertilization (IVF) in achieving better embryonic development and to provide a basis for the development of a pre-insemination culture medium specific for cumulus oocyte complexes (COCs). Methods: First, we examined the concentration of AR in the follicular fluid (FF) of patients who underwent routine IVF and explored the correlation between AR levels and oocyte maturation and subsequent embryonic development. Second, AR was added to the IVM medium to culture immature oocytes and investigate whether AR could improve the effects of IVM. Finally, we pioneered the use of a fertilization medium supplemented with AR for the pre-insemination culture of COCs to explore whether the involvement of AR can promote the maturation and fertilization of IVF oocytes, as well as subsequent embryonic development. Results: A total of 609 FF samples were examined, and a positive correlation between AR levels and blastocyst formation was observed. In our IVM study, the development potential and IVM rate of immature oocytes, as well as the fertilization rate of IVM oocytes in the AR-added groups, were ameliorated significantly compared to the control group (All P < 0.05). Only the IVM-50 group had a significantly higher blastocyst formation rate than the control group (P < 0.05). In the final IVF study, the maturation, fertilization, high-quality embryo, blastocyst formation, and high-quality blastocyst rates of the AR-added group were significantly higher than those of the control group (All P < 0.05). Conclusion: AR levels in the FF positively correlated with blastocyst formation, and AR involvement in pre-insemination cultures of COCs can effectively improve laboratory outcomes in IVF. Furthermore, AR can directly promote the in vitro maturation and developmental potential of human immature oocytes at an optimal concentration of 50 ng/ml.

Role of Menstrual Blood Stem Cell-Derived Secretome, Follicular Fluid, and Melatonin in Oocyte Maturation and Embryo Development in Polycystic Ovary Syndrome.

BACKGROUND: In vitro maturation has been considered an approach to mature oocytes derived from women with polycystic ovary syndrome (PCOS). It is suggested that the IVM of oocytes may benefit from mesenchymal stem cells derived conditioned medium (CM-MSC). OBJECTIVE: The purpose of this study was to determine the efficacy of a cocktail of menstrual blood stem cell (MenSCs)-derived secretome, along with follicular fluid and melatonin, in oocyte maturation and embryo development in PCOS. METHODS: Four hundred left germinal vesicle oocytes were collected from 100 PCOS patients and randomly divided into four treatment groups: 1) control, 2) secretome, 3) follicular fluid, and 4) melatonin. Oocyte maturation, fertilization rate, and embryo development were monitored, as well as the expression levels of oocyte-secreted factors (GDF9- BMP15), oocyte maturation (MPK3), and apoptosis (BAX- Bcl2). RESULTS: The rate of oocyte maturation increased in all test groups, but only the results for the SEC group were significant (P= 0.032). There were no significant differences in oocyte fertilization and embryo yield among groups. However, the quality of embryos significantly increased in the melatonin group compared to the control. Cytoplasmic maturation was confirmed by the expression of oocyte maturation-related genes using Real-time PCR. Additionally, the expression level of BCL-2 was significantly higher in the SEC-FF-MEL group than in the control group (p ≤ 0.01). CONCLUSION: Enrichment of IVM media using MenSCs-secretome, particularly along with melatonin, could be an effective strategy to improve oocyte maturation and embryo development in PCOS.

Interruption of the intratumor CD8+ T cell:Treg crosstalk improves the efficacy of PD-1 immunotherapy.

PD-1 blockade unleashes potent antitumor activity in CD8+ T cells but can also promote immunosuppressive T regulatory (Treg) cells, which may worsen the response to immunotherapy. Tumor-Treg inhibition is a promising strategy to improve the efficacy of checkpoint blockade immunotherapy; however, our understanding of the mechanisms supporting tumor-Tregs during PD-1 immunotherapy is incomplete. Here, we show that PD-1 blockade increases tumor-Tregs in mouse models of melanoma and metastatic melanoma patients. Mechanistically, Treg accumulation is not caused by Treg-intrinsic inhibition of PD-1 signaling but depends on an indirect effect of activated CD8+ T cells. CD8+ T cells produce IL-2 and colocalize with Tregs in mouse and human melanomas. IL-2 upregulates the anti-apoptotic protein ICOS on tumor-Tregs, promoting their accumulation. Inhibition of ICOS signaling before PD-1 immunotherapy improves control over immunogenic melanoma. Thus, interrupting the intratumor CD8+ T cell:Treg crosstalk represents a strategy to enhance the therapeutic efficacy of PD-1 immunotherapy.

In vitro matured oocytes have a higher developmental potential than in vivo matured oocytes after hormonal ovarian stimulation in Callithrix jacchus.

BACKGROUND: The common marmoset, Callithrix jacchus, is an invaluable model in biomedical research. Its use includes genetic engineering applications, which require manipulations of oocytes and production of embryos in vitro. To maximize the recovery of oocytes suitable for embryo production and to fulfil the requirements of the 3R principles to the highest degree possible, optimization of ovarian stimulation protocols is crucial. Here, we compared the efficacy of two hormonal ovarian stimulation approaches: 1) stimulation of follicular growth with hFSH followed by triggering of oocyte maturation with hCG (FSH + hCG) and 2) stimulation with hFSH only (FSH-priming). METHODS: In total, 14 female marmosets were used as oocyte donors in this study. Each animal underwent up to four surgical interventions, with the first three performed as ovum pick-up (OPU) procedures and the last one being an ovariohysterectomy (OvH). In total, 20 experiments were carried out with FSH + hCG stimulation and 18 with FSH-priming. Efficacy of each stimulation protocol was assessed through in vitro maturation (IVM), in vitro fertilization (IVF) and embryo production rates. RESULTS: Each study group consisted of two subgroups: the in vivo matured oocytes and the oocytes that underwent IVM. Surprisingly, in the absence of hCG triggering some of the oocytes recovered were at the MII stage, moreover, their number was not significantly lower compared to FSH + hCG stimulation (2.8 vs. 3.9, respectively (ns)). While the IVM and IVF rates did not differ between the two stimulation groups, the IVF rates of in vivo matured oocytes were significantly lower compared to in vitro matured ones in both FSH-priming and FSH + hCG groups. In total, 1.7 eight-cell embryos/experiment (OPU) and 2.1 eight-cell embryos/experiment (OvH) were obtained after FSH + hCG stimulation vs. 1.8 eight-cell embryos/experiment (OPU) and 5.0 eight-cell embryos/experiment (OvH) following FSH-priming. These numbers include embryos obtained from both in vivo and in vitro matured oocytes. CONCLUSION: A significantly lower developmental competence of the in vivo matured oocytes renders triggering of the in vivo maturation with hCG as a part of the currently used FSH-stimulation protocol unnecessary. In actual numbers, between 1 and 7 blastocysts were obtained following each FSH-priming. In the absence of further studies, FSH-priming appears superior to FSH + hCG stimulation in the common marmoset under current experimental settings.

Perinatal and neurodevelopmental outcomes of fetal isolated ventriculomegaly: a systematic review and meta-analysis.

Background: Isolated fetal ventriculomegaly can have a range of consequences, ranging from mild neurodevelopmental delay to perinatal death; the extent of these consequences often depend on the severity of ventriculomegaly. This systematic review and meta-analysis aims to investigate the impact of the degree of ventricular dilatation on the risk of neurodevelopmental delay and adverse perinatal outcomes in fetuses diagnosed with isolated fetal ventriculomegaly from gestational week 15 onwards. Methods: PubMed, Embase, Scopus and the Cochrane Library were searched electronically to identify studies investigating the prognosis of mild and/or severe isolated fetal ventriculomegaly. Articles were included if they reported neurodevelopmental or perinatal outcomes in fetuses prenatally diagnosed with isolated fetal ventriculomegaly from week 15 of gestation and onwards. Studies were excluded if they reported on non-isolated ventriculomegaly (IVM), failed to specify the degree of ventriculomegaly, were non-English papers, animal studies or published outside of the 21-year period of interest. Study quality was assessed by two independent reviewers using a modified version of the Newcastle-Ottawa Quality Assessment Scale. Ventriculomegaly was defined as either mild or severe when ventricular diameter measured as 10-15 or >15 mm, respectively. Meta-analyses were conducted for adverse neurodevelopmental outcome, intrauterine fetal demise and infant mortality. Results: Following the removal of duplicates, the search yielded 2,452 citations, of which 23 studies were included and 8 were eligible for meta-analysis. There were 767 and 347 cases of mild and severe isolated fetal ventriculomegaly, respectively. Adverse outcomes were consistently reported at a higher rate in severe cases than mild. The relative risks of adverse neurodevelopmental outcome, intrauterine fetal demise and infant mortality were 4.24 [95% confidence interval (CI): 2.46-7.30], 4.46 (95% CI: 1.64-12.11) and 6.02 (95% CI: 1.73-21.00), respectively, upon comparison of mild versus severe cases of isolated fetal ventriculomegaly. Conclusions: The likelihood of adverse neurodevelopmental and perinatal outcomes, including intrauterine and infant mortality, is increased in severe isolated fetal ventriculomegaly compared to mild isolated fetal ventriculomegaly.

Managing Primary Infertility in a Woman With Uterine Fibroids Utilizing Myomectomy and In Vitro Maturation (IVM) of Oocytes.

This case report demonstrates the management of primary infertility in a couple: the male was 37 years old and the female was 32 years old. The female had a submucosal uterine fibroid. Later, the female underwent a myomectomy to remove submucosal fibroids in the uterus after two failed intrauterine insemination (IUI) cycles. After six months of her recovery period, she underwent ovum pickup for an in vitro fertilization (IVF) cycle. During the process of ovum pickup (OPU), four oocytes were retrieved: three in the metaphase one (M1) stage and one in the metaphase two (M2) stage. Subsequently, the couple underwent in vitro maturation (IVM) of oocytes, where the M1 stage oocytes were cultured for six hours. The M1 stage oocytes progressed to the M2 stage. These oocytes were then injected with sperm, which resulted in the formation of two blastocysts. These blastocysts were then cryopreserved for three months, and after three months, these frozen embryos were then transferred, leading to the successful conception. The case study evaluates a couple who suffered from infertility. This study includes a treatment of myomectomy and in vitro maturation.

Successful pregnancy using immature oocytes retrieved from resected borderline ovarian tumor: a case report and literature review.

BACKGROUND: Despite the recent progress of fertility preservation technique, achievement of pregnancy in women with ovarian tumor is still challenging. Here, we report a case of OTO-IVM (ovarian tissue oocyte in-vitro maturation) resulting in a successful delivery. CASE PRESENTATION: The patient, a 33-year-old woman with a history of left borderline ovarian tumor (BOT) who underwent left salpingo-oophorectomy three years ago, presented with an enlarged right ovary during infertility treatment, indicating the recurrence of BOT. Because the patient disagreed with curative surgery and normal part-preservation surgery, we eventually performed OTO-IVM. A right salpingo-oophorectomy was first performed. Eight immature oocytes were immediately aspirated not only from visible follicles, but also from entire cortex for invisible follicles, of the removed ovary. In addition, IVM procedure generated six mature oocytes, and were subjected to intracytoplasmic sperm injection (ICSI). Accordingly, three embryos were obtained and cryopreserved. Three months after surgery, hormone replacement therapy was initiated, and a frozen-thawed embryo was transferred, resulting in a successful pregnancy. Although a cesarean section was performed at 36 weeks due to maternal ileus, the baby was delivered without complications. CONCLUSIONS: This report indicates this treatment to be an effective approach for fertility preservation in BOT patients, especially, the importance of collecting oocytes from the entire ovarian cortex was suggested.

Updates on traditional methods for combating malaria and emerging Wolbachia-based interventions.

The escalating challenge of malaria control necessitates innovative approaches that extend beyond traditional control strategies. This review explores the incorporation of traditional vector control techniques with emerging Wolbachia-based interventions. Wolbachia, a naturally occurring bacteria, offers a novel approach for combatting vector-borne diseases, including malaria, by reducing the mosquitoes' ability to transmit these diseases. The study explores the rationale for this integration, presenting various case studies and pilot projects that have exhibited significant success. Employing a multi-dimensional approach that includes community mobilization, environmental modifications, and new biological methods, the paper posits that integrated efforts could mark a turning point in the struggle against malaria. Our findings indicate that incorporating Wolbachia-based strategies into existing vector management programs not only is feasible but also heightens the efficacy of malaria control initiatives in different countries especially in Pakistan. The paper concludes that continued research and international collaboration are imperative for translating these promising methods from the laboratory to the field, thereby offering a more sustainable and effective malaria control strategy.

Poland Syndrome in a Pregnancy From an Assisted Reproductive Technology (ART) Cycle With In Vitro Maturation (IVM) and Rescue Intracytoplasmic Sperm Injection (ICSI).

Poland syndrome is a congenital anatomical anomaly, characterised by partial or total aplasia of one side of the body causing abnormalities affecting the chest, shoulder, and upper limb. The exact mechanism that leads to this syndrome is unknown, but an abnormality in the vasculature formation or interruption of the blood supply of the subscapular artery and its branches early in development may be the main cause. Depending on the underlying mechanism, the syndrome has several expressions with some hardly being detectable and others not even being compatible with life. Here, we present a case of pregnancy from an assisted reproductive technology (ART) cycle with in vitro maturation (IVM) and rescue intra cytoplasmic sperm injection (ICSI), which resulted in the in-utero death of the foetus. The subsequent necropsy revealed a variation of Poland syndrome.

Short- and Long-Term Storage of Non-Domesticated European Mouflon (Ovis aries musimon) Cumulus-Oocyte Complexes Recovered in Field Conditions.

Reproductive biotechnologies can be used as a supporting tool, through gamete conservation and in vitro embryo production, in the preservation of invaluable and irreplaceable animal genetic resources. In the present study, immature mouflon cumulus-oocyte complexes (COCs) collected from ovariectomized female ovaries underwent short- or long-term conservation (24 h maintained in Earle's/Hank's (EH) medium or vitrification) under field conditions and afterwards transported to the laboratory where they were cultured for in vitro maturation (IVM) and assessed for oocyte meiotic competence and bioenergetic-oxidative status. Utilization of both storage techniques led to COC morphology preservation, as well as cumulus expansion and oocyte meiotic resumption after the IVM procedure. Quantitative bioenergetic-oxidative parameters were reduced in vitrified oocytes compared with EH ones. Immature COC storage needs to be optimized in both domesticated and non-domesticated sheep as a part of the strategy to avoid the loss of valuable genotypes of these animal species.

Aedes aegypti Controls AE. Aegypti: SIT and IIT-An Overview.

The sterile insect technique (SIT) and the incompatible insect technique (IIT) are emerging and potentially revolutionary tools for controlling Aedes aegypti (L.), a prominent worldwide mosquito vector threat to humans that is notoriously difficult to reduce or eliminate in intervention areas using traditional integrated vector management (IVM) approaches. Here we provide an overview of the discovery, development, and application of SIT and IIT to Ae. aegypti control, and innovations and advances in technology, including transgenics, that could elevate these techniques to a worldwide sustainable solution to Ae. aegypti when combined with other IVM practices.

Isoliquiritin can cause mitochondrial dysfunction and regulate Nrf2 to affect the development of mouse oocytes.

IsoliQuirtigenin (ILG) has been widely studied in somatic cells and tissues, but less in reproductive development. It is a kind of widely used food additive. In this study, it was found that ILG could significantly increase the levels of ROS,GSH and MMP in mouse oocytes (P < 0.01). In order to explore the cause of this phenomenon, it was found that the abnormal distribution of mitochondria and ATP synthesis levels were significantly increased (P < 0.05). At this time, we made a reasonable hypothesis that ILG affected mitochondrial function. In subsequent studies, it was found that the endogenous ROS accumulation level in mitochondria was significantly increased. After continuous RT-PCR screening, it was found that the expression of Nrf2 was significantly inhibited (P < 0.01). Its upstream and downstream FOXO3 GPX1, CAT, SOD2, SIRT1 gene also appear different degree of significant change (P < 0.05), in which the lower expression of NADP + (P < 0.05) illustrates the mitochondrial ATP synthesis electronic chain were suppressed, it also has the reason, By inhibiting electron chain and ATP synthesis, ILG leads to oocyte apoptosis and initiation of autophagy, reducing oocyte and its subsequent developmental potential.

Comparison of luteal phase and follicular phase in-vitro maturation in women with oocyte maturation abnormalities.

RESEARCH QUESTION: Are there differences in immature oocyte retrieval following luteal phase in-vitro maturation (IVM) compared with follicular phase IVM in women with oocyte maturation abnormalities (OMAs). DESIGN: From January 2019 to May 2023, a retrospective cohort study at a private IVF centre included 36 women with 53 IVM cycles in Group 1 (follicular phase) and 24 women with 32 IVM cycles in Group 2 (luteal phase). Additionally, nine women had both follicular and luteal phase IVM cycles for intracycle variability analysis. RESULTS: There were no differences in oocyte maturation stages between the groups at collection. Group 1 and Group 2 exhibited comparable median metaphase II oocyte rates per patient at 48 h after collection [40.0%, interquartile range (IQR) 0.0-66.7% versus 22.5%, IQR 0.0-52.9%] (P = 0.53). The median fertilization rate in Group 1 (66.7%, IQR 50.0-66.7%) was found to be comparable with that in Group 2 (66.7%, IQR 50.0-66.7%). There were no significant differences in the yielded embryo grades and pregnancy rates between the groups. Comparing follicular and luteal phase IVM within the same menstrual cycle in nine patients, no differences were observed in metaphase II oocyte maturation rates (P > 0.05). CONCLUSIONS: This study found no significant differences in oocyte maturation, fertilization rate, embryo quality or pregnancy outcomes between luteal phase and follicular phase IVM in women with OMAs. These findings suggest that luteal phase IVM can be used similarly to follicular phase IVM, offering a potential avenue to enhance embryo yield for women with OMAs.

Oocyte in-vitro maturation primed with letrozole-HCG versus FSH-HCG in women with oocyte maturation abnormalities: a retrospective study.

RESEARCH QUESTION: Are there differences between in-vitro maturation (IVM) primed with letrozole-human chorionic gonadotrophin (HCG) and IVM primed with FSH-HCG in women with oocyte maturation abnormalities (OMAs), defined as at least two failed IVF cycles where immature oocytes were retrieved? DESIGN: This retrospective study was conducted at a private fertility clinic from January 2009 to April 2023. The final analysis included 75 women in Group 1 (IVM primed with FSH-HCG) and 52 women in Group 2 (IVM primed with letrozole-HCG). RESULTS: A significantly higher median number of oocytes was obtained in Group 1 compared with Group 2 {9 [interquartile range (IQR) 1-5] versus 5 (IQR 1-18); P < 0.001}. However, no differences in oocyte maturation stage at collection were found between the groups (P > 0.05). At the end of IVM, Group 1 had 73/666 mature oocytes and Group 2 had 106/322 mature oocytes, and the median metaphase II oocyte rate per patient was higher in Group 2 [33.3% (IQR 66.7-100.0%) versus 0.0% (IQR 0.0-22.2%); P < 0.001]. Moreover, Group 2 demonstrated a higher median fertilization rate [66.7% (IQR 50.0-100.0%) versus 50.0% (IQR 0.0-66.7%); P = 0.027]. Group 2 had a higher proportion of Grade 2 embryos (58.5% versus 6.3%), and Group 1 had a higher proportion of Grade 3 embryos (93.8% vs 24.4%; P < 0.001). Notably, all pregnancies obtained in the study were in Group 2 (5 versus 0; P = 0.042). CONCLUSIONS: IVM primed with letrozole-HCG in women with prior failed IVF cycles due to OMAs may result in mature oocytes, clinical pregnancies and live births. The effectiveness of letrozole priming for the subtypes of OMAs needs further investigation, with studies including greater numbers of cases.

Addition of rapamycin or co-culture with cumulus cells from younger reproductive age women does not improve rescue in vitro oocyte maturation or euploidy rates in older reproductive age women.

Both spontaneously conceived pregnancies and those achieved using assisted reproduction decline with advancing maternal age. In this study, we tested if rapamycin and/or cumulus cells (CCs) from young donors could improve oocyte maturation and euploidy rates of germinal vesicle (GV) stage oocytes obtained from older women of reproductive age. A total of 498 GVs from 201 women >38 years (40.6 ± 1.8, mean ± SD) were included. GVs were randomly assigned into five groups for rescue IVM: control (with no CCs and no rapamycin); with autologous CCs; with autologous CCs and rapamycin; with CCs from young women (<35 years); and with CCs from young women and rapamycin. After 24 h of culture, the first polar body (PB) was biopsied in metaphase II oocytes, and the cytogenetic constitution was assessed using next-generation sequencing for both oocytes and PBs. Comparable maturation rates were found (56.2%, 60.0%, 46.5%, 51.7%, and 48.5% for groups 1-5, respectively; P = 0.30). Similarly, comparable euploidy rates were observed in the five groups (41.5%, 37.8%, 47.2%, 43.6%, and 47.8% for Groups 1-5, respectively; P = 0.87). Our findings indicate that rescue IVM is effective for obtaining mature euploid oocytes in older women of reproductive age, and that incubation with rapamycin or CCs obtained from young donors does not improve the maturation or euploidy rate.

Effects of limonin on oxidative stress and early apoptosis in oocytes during in vitro maturation.

To investigate the effects of limonin (Lim) on oxidative stress and early apoptosis in bovine oocytes during in vitro maturation (IVM), different concentrations of Lim (0, 10, 20, 50 µmol/L) were added to bovine IVM medium. Oocyte maturation rates and development 24 h after in vitro fertilization (IVF) were examined to determine the optimal Lim concentration. The optimal Lim concentration was added to the IVM medium, and 0 µmol/L Lim was used as the control. Immunofluorescence staining was used to detect the abnormal rate of spindle assembly, reactive oxygen species (ROS), glutathione (GSH), mitochondrial membrane potential (MMP) levels, mitochondrial distribution, and the fluorescence intensity of cathepsin B (CB)-active LC3 protein. RT‒qPCR was used to detect the mRNA expression levels of antioxidant-, apoptosis- and autophagy-related genes in oocytes. The total number of blastocysts and the proportion of apoptotic cells among blastocysts were detected. The results showed that the PBI ejection rate, cleavage rate and blastocyst rate of bovine oocytes in the 20 µmol/L Lim group were significantly higher than those in the control group (P < 0.05). Compared with those in the control group, ROS levels, abnormal mitochondrial distribution, the proportion of abnormal spindle assembly, CB activity and LC3 protein fluorescence intensity of oocytes in the 20 µmol/L Lim group were significantly decreased (P < 0.05), and GSH and MMP levels were significantly increased (P < 0.05). The expression of antioxidant genes (Prdx3, Prdx6, Sirt1) and antiapoptotic genes (Bcl-xl, Survivin) were significantly upregulated (P < 0.05), and the expression levels of proapoptotic genes (Caspase-4, BAX) and autophagy-related genes (LC3) were significantly downregulated (P < 0.05). The total number of cells among in vitro fertilized embryos was significantly increased (P < 0.05), and the apoptosis rate of blastocysts was significantly decreased (P < 0.05). Here, we show that Lim exerts positive effects on bovine oocyte IVM by regulating REDOX homeostasis, reducing spindle damage and enhancing mitochondrial function during IVM, thereby inhibiting oocyte apoptosis and autophagy.

A fresh start for IVM: capacitating the oocyte for development using pre-IVM.

BACKGROUND: While oocyte IVM is practiced sporadically it has not achieved widespread clinical practice globally. However, recently there have been some seminal advances in our understanding of basic aspects of oocyte biology and ovulation from animal studies that have led to novel approaches to IVM. A significant recent advance in IVM technology is the use of biphasic IVM approaches. These involve the collection of immature oocytes from small antral follicles from minimally stimulated patients/animals (without hCG-priming) and an ∼24 h pre-culture of oocytes in an advanced culture system ('pre-IVM') prior to IVM, followed by routine IVF procedures. If safe and efficacious, this novel procedure may stand to make a significant impact on human ART practices. OBJECTIVE AND RATIONALE: The objectives of this review are to examine the major scientific advances in ovarian biology with a unique focus on the development of pre-IVM methodologies, to provide an insight into biphasic IVM procedures, and to report on outcomes from animal and clinical human data, including safety data. The potential future impact of biphasic IVM on ART practice is discussed. SEARCH METHODS: Peer review original and review articles were selected from PubMed and Web of Science searches for this narrative review. Searches were performed using the following keywords: oocyte IVM, pre-IVM, biphasic IVM, CAPA-IVM, hCG-triggered/primed IVM, natural cycle IVF/M, ex-vivo IVM, OTO-IVM, oocyte maturation, meiotic competence, oocyte developmental competence, oocyte capacitation, follicle size, cumulus cell (CC), granulosa cell, COC, gap-junction communication, trans-zonal process, cAMP and IVM, cGMP and IVM, CNP and IVM, EGF-like peptide and IVM, minimal stimulation ART, PCOS. OUTCOMES: Minimizing gonadotrophin use means IVM oocytes will be collected from small antral (pre-dominant) follicles containing oocytes that are still developing. Standard IVM yields suboptimal clinical outcomes using such oocytes, whereas pre-IVM aims to continue the oocyte's development ex vivo, prior to IVM. Pre-IVM achieves this by eliciting profound cellular changes in the oocyte's CCs, which continue to meet the oocyte's developmental needs during the pre-IVM phase. The literature contains 25 years of animal research on various pre-IVM and biphasic IVM procedures, which serves as a large knowledge base for new approaches to human IVM. A pre-IVM procedure based on c-type natriuretic peptide (named 'capacitation-IVM' (CAPA-IVM)) has undergone pre-clinical human safety and efficacy trials and its adoption into clinical practice resulted in healthy live birth rates not different from conventional IVF. WIDER IMPLICATIONS: Over many decades, improvements in clinical IVM have been gradual and incremental but there has likely been a turning of the tide in the past few years, with landmark discoveries in animal oocyte biology finally making their way into clinical practice leading to improved outcomes for patients. Demonstration of favorable clinical results with CAPA-IVM, as the first clinically tested biphasic IVM system, has led to renewed interest in IVM as an alternative, low-intervention, low-cost, safe, patient-friendly ART approach, and especially for patients with PCOS. The same new approach is being used as part of fertility preservation in patients with cancer and holds promise for social oocyte freezing.

Three-dimensional glass scaffolds improve the In Vitro maturation of porcine cumulus-oocyte complexes and subsequent embryonic development after parthenogenetic activation.

In vitro maturation (IVM) methods for porcine oocytes are still deficient in achieving full developmental capacity, as the currently available oocyte in vitro culture systems still have limitations. In vitro embryo production must also improve the porcine oocyte IVM system to acquire oocytes with good developmental potential. Herein, we tested a three-dimensional (3D) glass scaffold culture system for porcine oocyte maturation. After 42 h, we matured porcine cumulus-oocyte complexes (COCs) on either two-dimensional glass dishes (2D-B), two-dimensional microdrops (2D-W), or 3D glass scaffolds. The 3D glass scaffolds were tested for porcine oocyte maturation and embryonic development. Among these culture methods, the extended morphology of the 3D group maintained a 3D structure better than the 2D-B and 2D-W groups, which had flat COCs that grew close to the bottom of the culture vessel. The COCs of the 3D group had a higher cumulus expansion index and higher first polar body extrusion rate, cleavage rate, and blastocyst rate of parthenogenetic embryos than the 2D-B group. In the 3D group, the cumulus-expansion-related gene HAS2 and anti-apoptotic gene Bcl-2 were significantly upregulated (p < 0.05), while the pro-apoptotic gene Caspase3 was significantly downregulated (p < 0.05). The blastocysts of the 3D group had a higher relative expression of Bcl-2, Oct4, and Nanog than the other two groups (p < 0.05). The 3D group also had a more uniform distribution of mitochondrial membrane potential and mitochondria (p < 0.05), and its cytoplasmic active oxygen species content was much lower than that in the 2D-B group (p < 0.05). These results show that 3D glass scaffolds dramatically increased porcine oocyte maturation and embryonic development after parthenogenetic activation, providing a suitable culture model for porcine oocytes.