Commercially available enhanced in vitro maturation medium does not improve maturation of germinal vesicle and metaphase I oocytes in standard in vitro fertilization cases

Human-induced pluripotent stem cell-derived ovarian support cell co-culture improves oocyte maturation in vitro after abbreviated gonadotropin stimulation

STUDY QUESTION

Can in vitro maturation (IVM) and developmental competence of human oocytes be improved by co-culture with ovarian support cells (OSCs) derived from human-induced pluripotent stem cells (hiPSCs)?

SUMMARY ANSWER

OSC-IVM significantly improves the rates of metaphase II (MII) formation and euploid Day 5 or 6 blastocyst formation, when compared to a commercially available IVM system.

WHAT IS KNOWN ALREADY

IVM has historically shown highly variable performance in maturing oocytes and generating oocytes with strong developmental capacity, while limited studies have shown a positive benefit of primary granulosa cell co-culture for IVM. We recently reported the development of OSCs generated from hiPSCs that recapitulate dynamic ovarian function in vitro.

STUDY DESIGN, SIZE, DURATION

The study was designed as a basic science study, using randomized sibling oocyte specimen allocation. Using pilot study data, a prospective sample size of 20 donors or at least 65 oocytes per condition were used for subsequent experiments. A total of 67 oocyte donors were recruited to undergo abbreviated gonadotropin stimulation with or without hCG triggers and retrieved cumulus-oocyte complexes (COCs) were allocated between the OSC-IVM or control conditions (fetal-like OSC (FOSC)-IVM or media-only IVM) in three independent experimental design formats. The total study duration was 1 April 2022 to 1 July 2023.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Oocyte donors between the ages of 19 and 37 years were recruited for retrieval after informed consent, with assessment of anti-Mullerian hormone, antral follicle count, age, BMI and ovarian pathology used for inclusion and exclusion criteria. In experiment 1, 27 oocyte donors were recruited, in experiment 2, 23 oocyte donors were recruited, and in experiment 3, 17 oocyte donors and 3 sperm donors were recruited. The OSC-IVM culture condition was composed of 100 000 OSCs in suspension culture with hCG, recombinant FSH, androstenedione, and doxycycline supplementation. IVM controls lacked OSCs and contained either the same supplementation, FSH and hCG only (a commercial IVM control), or FOSCs with the same supplementation (Media control). Experiment 1 compared OSC-IVM, FOSC-IVM, and a Media control, while experiments 2 and 3 compared OSC-IVM and a commercial IVM control. Primary endpoints in the first two experiments were the MII formation (i.e. maturation) rate and morphological quality assessment. In the third experiment, the fertilization and embryo formation rates were assessed with genetic testing for aneuploidy and epigenetic quality in blastocysts.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed a statistically significant improvement (∼1.5×) in maturation outcomes for oocytes that underwent IVM with OSCs compared to control Media-IVM and FOSC-IVM in experiment 1. More specifically, the OSC-IVM group yielded a MII formation rate of 68% ± 6.83% SEM versus 46% ± 8.51% SEM in the Media control (P = 0.02592, unpaired t-test). FOSC-IVM yielded a 51% ± 9.23% SEM MII formation rate which did not significantly differ from the media control (P = 0.77 unpaired t-test). Additionally, OSC-IVM yielded a statistically significant ∼1.6× higher average MII formation rate at 68% ± 6.74% when compared to 43% ± 7.90% in the commercially available IVM control condition (P = 0.0349, paired t-test) in experiment 2. Oocyte morphological quality between OSC-IVM and the controls did not significantly differ. In experiment 3, OSC-IVM oocytes demonstrated a statistically significant improvement in Day 5 or 6 euploid blastocyst formation per COC compared to the commercial IVM control (25% ± 7.47% vs 11% ± 3.82%, P = 0.0349 logistic regression). Also in experiment 3, the OSC-treated oocytes generated blastocysts with similar global and germline differentially methylated region epigenetic profiles compared commercial IVM controls or blastocysts after either conventional ovarian stimulation.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

While the findings of this study are compelling, the cohort size remains limited and was powered on preliminary pilot studies, and the basic research nature of the study limits generalizability compared to randomized control trials. Additionally, use of hCG-triggered cycles results in a heterogenous oocyte cohort, and potential differences in the underlying maturation state of oocytes pre-IVM may limit or bias findings. Further research is needed to clarify and characterize the precise mechanism of action of the OSC-IVM system. Further research is also needed to establish whether these embryos are capable of implantation and further development, a key indication of their clinical utility.

WIDER IMPLICATIONS OF THE FINDINGS

Together, these findings demonstrate a novel approach to IVM with broad applicability to modern ART practice. The controls used in this study are in line with and have produced similar to findings to those in the literature, and the outcome of this study supports findings from previous co-culture studies that found benefits of primary granulosa cells on IVM outcomes. The OSC-IVM system shows promise as a highly flexible IVM approach that can complement a broad range of stimulation styles and patient populations. Particularly for patients who cannot or prefer not to undergo conventional gonadotropin stimulation, OSC-IVM may present a viable path for obtaining developmentally competent, mature oocytes.

STUDY FUNDING/COMPETING INTEREST(S)

A.D.N., A.B.F., A.G., B.P., C.A., C.C.K., F.B., G.R., K.S.P., K.W., M.M., P.C., S.P., and M.-J.F.-G. are shareholders in the for-profit biotechnology company Gameto Inc. P.R.J.F. declares paid consultancy for Gameto Inc. P.C. also declares paid consultancy for the Scientific Advisory Board for Gameto Inc. D.H.M. has received consulting services from Granata Bio, Sanford Fertility and Reproductive Medicine, Gameto, and Buffalo IVF, and travel support from the Upper Egypt Assisted Reproduction Society. C.C.K., S.P., M.M., A.G., B.P., K.S.P., G.R., and A.D.N. are listed on a patent covering the use of OSCs for IVM: U.S. Provisional Patent Application No. 63/492,210. Additionally, C.C.K. and K.W. are listed on three patents covering the use of OSCs for IVM: U.S. Patent Application No. 17/846,725, U.S Patent Application No. 17/846,845, and International Patent Application No.: PCT/US2023/026012. C.C.K., M.P.S., and P.C. additionally are listed on three patents for the transcription factor-directed production of granulosa-like cells from stem cells: International Patent Application No.: PCT/US2023/065140, U.S. Provisional Application No. 63/326,640, and U.S. Provisional Application No. 63/444,108. The remaining authors have no conflicts of interest to declare.

Potential Development of Vitrified Immature Human Oocytes: Influence of the Culture Medium and the Timing of Vitrification

How does the in vitro maturation (IVM) medium and the vitrification procedure affect the survival of germinal vesicle (GV) oocytes obtained from stimulated cycles and their development to the blastocyst stage? In total, 1085 GV human oocytes were obtained after women underwent a cycle of controlled ovarian stimulation, and these oocytes were subjected to IVM before or after their vitrification. IVM was carried out in two commercial culture media not specifically designed for maturation. MII oocytes were then activated and embryo development until day 6 was evaluated. According to the results, a higher percentage of oocytes reach the MII stage if they are vitrified before they undergo IVM. Nevertheless, the medium used and the sample size determine whether these differences become significant or not. Similar survival rates and development to blastocysts were observed in all the conditions studied.

Comparing the IVM laboratory outcomes between stimulated IVF with unstimulated natural cycles

Recently, more attention has been raised towards fertility preservation in women with cancer. One option is in vitro maturation (IVM) of the immature oocytes as there is not enough time for induction of an ovarian stimulation protocol. The aim was to compare the IVM laboratory outcomes between stimulated and unstimulated (natural) in vitro fertilization (IVF) cycles. In total, 234 immature oocytes collected from 15 cancer patients who underwent an IVM programme (natural IVM) and 23 IVF cycles with a controlled ovarian hyperstimulation protocol (stimulated IVM) were analyzed. The oocyte morphology, zona pellucida (ZP), and meiotic spindle presence were measured using PolScope technology. Also, the rates of oocyte maturation and fertilization were assessed in both groups. The IVM rate was higher in the stimulated cycle (P < 0.05), but the fertilization rate was insignificant in comparison with unstimulated cycles. There were no significant differences in the spindle visualization and ZP birefringence scoring between the groups (P > 0.05). The oocyte normal morphology was better in the stimulated cycle compared with the natural cycle (P < 0.05). In conclusion, IVM can be recommended for cancer patients as an alternative treatment when there is insufficient time for conventional IVF before chemotherapy initiation.

High efficiency of homemade culture medium supplemented with GDF9-β in human oocytes for rescue in vitro maturation

Objective

Optimizing culture media for the incubation of immature oocytes is a vital strategy to increase the oocyte maturation rate during in vitro maturation (IVM) programs. This study evaluated the IVM and fertilization rates of human germinal vesicle (GV) and metaphase I (MI) oocytes using two different maturation media (commercial and homemade) with or without growth differentiation factor 9-β (GDF9-β). supplementation.

Methods

Immature oocytes from intracytoplasmic sperm injection (ICSI) cycles were collected and assigned to one of two IVM culture media (commercial or homemade; cleavage-stage base). After maturation, MII oocytes were examined under an inverted microscope for the presence of the polar body, zona pellucida (ZP) birefringence, and meiotic spindle (MS) visualization after maturation in four conditions (commercial or homemade medium, with or without GDF9-β. ICSI was done for matured oocytes, and fertilization was confirmed by the visualization of two distinct pronuclei and two polar bodies.

Results

No significant differences were found between the two culture media in terms of the time and rate of oocyte maturation or the rate of fertilization (p>0.05). Growth factor supplementation increased the 24-hour maturation rate for both GV and MI oocytes only in homemade medium. The maturation rate after 24 hours was higher for MI oocytes (p<0.05). Similar results were observed for MS visualization and ZP structure in both types of media (p>0.05).

Conclusion

Higher rates of oocyte maturation and fertilization were observed after application of homemade medium supplemented with GDF9-β. Therefore, this combination may be recommended as an alternative for clinical IVM programs.

Factors Influencing the In Vitro Maturation (IVM) of Human Oocyte

In vitro maturation (IVM) of oocytes is a promising assisted reproductive technology (ART) deemed as a simple and safe procedure. It is mainly used in patients with impaired oocyte maturation and in fertility preservation for women facing the risk of losing fertility. However, to date, it is still not widely used in clinical practice because of its underperformance. The influencing factors, such as biphasic IVM system, culture medium, and the supplementation, have a marked effect on the outcomes of oocyte IVM. However, the role of different culture media, supplements, and follicular priming regimens in oocyte IVM have yet to be fully clarified and deserve further investigation.

In vitro rescue immature oocytes - a literature review

Immature oocytes retrieved from in vitro fertilization (IVF) and clinical in vitro maturation (IVM) is a common problem, especially in patients with advanced age, poor ovarian response (POR), or polycystic ovary syndrome (PCOS). Considering there is no common name to describe this group of oocytes, we suggest naming all of immature oocytes retrieved from IVF and clinical IVM cycles as 'Medical Unusable Oocytes' (MUO) as none of them will be used for subsequent treatment and will eventually be discarded. Scientists attempt to improve the clinical utilization rate of MUO instead of discarding them. Rescue IVM and mitochondria supplementation may be available approaches to mature MUO. We propose a specific definition of rescue IVM, namely the cultivation and maturation of immature oocytes in vitro collected from IVF cycles with human chorionic gonadotropin (hCG) trigger. Rescue IVM is usually mixed up with clinical IVM. Clarification of the differences between rescue IVM and clinical IVM is necessary. This manuscript aims to clarify the rather confusing IVM procedures and review existing methods of improving rescue IVM, currently available information on the success rate, and explore the future possibility of rescue IVM serving as a promising tool in reproductive medicine.

Oocyte in vitro maturation: A sytematic review

In vitro maturation (IVM) is one of the most controversial aspects of assisted reproductive technology. Although it has been studied extensively, it is still not a conventional treatment option and is accepted as an alternative treatment. However, studies have shown that IVM can be used in almost all areas where in vitro fertilization (IVF) is used and it has a strong place in fertility protection and Ovarian Hyperstimulation syndrome management. The aim of this systematic review was to address all aspects of the current knowledge of IVM treatment together with the evolution of IVM and IVF.

The effects of different types of media on in vitro maturation outcomes of human germinal vesicle oocytes retrieved in intracytoplasmic sperm injection cycles

OBJECTIVE

Optimizing in vitro maturation (IVM) media to achieve better outcomes has been a matter of interest in recent years. The aim of this prospective clinical trial was to investigate the effects of different media on the IVM outcomes of immature oocytes at the germinal vesicle (GV) stage.

METHODS

A total of 400 immature oocytes at the GV stage with normal morphology were retrieved from 320 infertile women aged 31±4.63 years during stimulated intracytoplasmic sperm injection (ICSI) cycles. They were divided into groups of homemade IVM medium (I, n=100), cleavage medium (II, n=100), blastocyst medium (III, n=100), and Sage IVM medium (IV, n=100) and cultured for 24 to 48 hours at 37℃. ICSI was performed, and the rates of fertilization and embryo formation were compared across the four groups.

RESULTS

In the 400 retrieved GV oocytes, the total maturation rates showed significant differences in groups I to IV (55%, 53%, 78%, and 68%, respectively, p<0.001). However, there were no significant differences in the fertilization, embryo formation, or arrest rates of metaphase II oocytes across these groups. In all groups, GV maturation was mostly completed after 24 hours, with fewer oocytes requiring 48 hours to mature (p<0.01). Moreover, the rate of high-quality embryos was higher in group IV than in the other groups (p=0.01).

CONCLUSION

The quality of the IVM medium was found to affect clinical IVM outcomes. Additionally, blastocyst medium may be a good choice in IVM/ICSI cycles as an alternative IVM medium.