Retrieval and in vitro maturation of human oocytes from ovaries removed during surgery for endometrial carcinoma: a novel strategy for human oocyte research

Remodeling of maternal mRNA through poly(A) tail orchestrates human oocyte-to-embryo transition

Poly(A)-tail-mediated post-transcriptional regulation of maternal mRNAs is vital in the oocyte-to-embryo transition (OET). Nothing is known about poly(A) tail dynamics during the human OET. Here, we show that poly(A) tail length and internal non-A residues are highly dynamic during the human OET, using poly(A)-inclusive RNA isoform sequencing (PAIso-seq). Unexpectedly, maternal mRNAs undergo global remodeling: after deadenylation or partial degradation into 3'-UTRs, they are re-polyadenylated to produce polyadenylated degradation intermediates, coinciding with massive incorporation of non-A residues, particularly internal long consecutive U residues, into the newly synthesized poly(A) tails. Moreover, TUT4 and TUT7 contribute to the incorporation of these U residues, BTG4-mediated deadenylation produces substrates for maternal mRNA re-polyadenylation, and TENT4A and TENT4B incorporate internal G residues. The maternal mRNA remodeling is further confirmed using PAIso-seq2. Importantly, maternal mRNA remodeling is essential for the first cleavage of human embryos. Together, these findings broaden our understanding of the post-transcriptional regulation of maternal mRNAs during the human OET.

Functional substitution of zona pellucida with modified sodium hyaluronate gel in human embryos

PURPOSE

Zona pellucida-free (ZP-free) embryos often fail to achieve good developmental outcomes and are routinely discarded in assisted reproductive laboratories. Existing attempts to rescue ZP-free embryos are not widely used due to operational complexity and high technical requirements. To handle cases with missing ZP, we applied modified sodium hyaluronate gel (MSHG) to embryo culture to determine if it can function as a substitute for human zona pellucida.

METHODS

The developmental process and the blastocyst formation rate of embryos were analyzed in both mouse and human. The first clinical application of MSHG was reported, and the pregnancy outcome was continuously followed up.

RESULTS

Human and mouse ZP-free embryos cultured with MSHG showed a blastocyst formation rate similar to ZP-intact embryos. MSHG improves blastocysts formation rate by maintaining blastomere spatial arrangement at early stages. Compared to ZP-free embryos, the proportion of tetrahedrally arranged blastomeres at the 4-cell stage increased significantly in embryos cultured with MSHG in humans. A ZP-free blastocyst cultured in MSHG with the highest score was successfully implanted after day 5 transplantation and developed normally.

CONCLUSION

These data demonstrate that MSHG can substitute the function of zona pellucida and rescue human ZP-free embryos during assisted reproductive technology.

Translatome and transcriptome co-profiling reveals a role of TPRXs in human zygotic genome activation

Translational regulation plays a critical role during the oocyte-to-embryo transition (OET) and zygotic genome activation (ZGA). Here, we integrated ultra-low-input Ribo-seq with mRNA-seq to co-profile the translatome and transcriptome in human oocytes and early embryos. Comparison with mouse counterparts identified widespread differentially translated genes functioning in epigenetic reprogramming, transposon defense, and small RNA biogenesis, in part driven by species-specific regulatory elements in 3' untranslated regions. Moreover, PRD-like homeobox transcription factors, including TPRXL, TPRX1, and TPRX2, are highly translated around ZGA. TPRX1/2/L knockdown leads to defective ZGA and preimplantation development. Ectopically expressed TPRXs bind and activate key ZGA genes in human embryonic stem cells. These data reveal the conservation and divergence of translation landscapes during OET and identify critical regulators of human ZGA.

Kinetics of meiotic maturation in oocytes from unstimulated ovaries and duration of pronucleus presence and preimplantation development

OBJECTIVE

To evaluate the meaning of meiotic maturation kinetics and duration of pronucleus presence (DPP) for parthenogenetic activation outcome.

DESIGN

Retrospective study.

SETTING

University hospital.

PATIENT(S)

Eight patients with endometrioid adenocarcinoma and 65 patients who underwent in vitro fertilization (IVF) with intracytoplasmic sperm injection (ICSI).

INTERVENTION(S)

After collection of oocytes from nonstimulated ovaries of patients with endometrioid adenocarcinoma, in vitro maturation (IVM) and parthenogenetic activation performed with time-lapse imaging; after ICSI, embryos similarly incubated with time-lapse imaging.

MAIN OUTCOME MEASURE(S)

Timing of the release of the first polar body (fPB), DPP, and developmental stage with IVM and parthenogenetic activation; after ICSI, assessment of DPP and preimplantation developmental stage.

RESULT(S)

With IVM, 55.2% of oocytes matured; 53.1% of fPBs were released within 24 hours, and 46.9% of fPBs were released after 24 hours. Regarding developmental stage, oocytes that released fPB later during IVM tended to develop more than oocytes that released the fPB within 24 hours. For embryos from parthenogenetic activation the DPP was statistically significantly shorter than the DPP of embryos from ICSI. With ICSI, the DPP was statistically significantly shorter in embryos that developed to ≥8 cells than embryos whose final development included ≤7 cells. The development rate in parthenogenetic activation was statistically significantly lower than that in ICSI.

CONCLUSION(S)

Embryo development is negatively affected by DPP that is too short or too long. When the DPP was short with parthenogenetic activation, embryo development did not proceed, indicating that DPP is an important determinant of parthenogenetic activation outcomes as with the timing of fPB release.

Oocyte collection and in vitro maturation after train transportation of human follicular fluid aspirated from resected non-stimulated ovaries of patients with endometrial adenocarcinoma

PURPOSE

Immature human oocytes from resected ovaries can be used for research and fertility preservation, though it is unknown whether it is feasible to transport oocytes for these purposes. This study examined in vitro maturation (IVM) outcomes after the transportation of human follicular fluid (HFF) containing oocytes.

METHODS

Fourteen patients with endometrial adenocarcinoma were enrolled. Oocytes obtained from the resected ovaries of seven patients were transported with HFF by railway (transportation group). Samples of HFF from the other seven patients were not transported, and IVM was performed promptly (non-transportation group). The results of oocyte retrieval and IVM were compared.

RESULTS

The average ages in the transportation and non-transportation groups were 40.1 ± 2.0 and 39.6 ± 1.8 years, respectively, and the average numbers of collected oocytes were 8.1 ± 8.4 and 5.1 ± 5.1, respectively. There was a significant negative correlation between the number of collected oocytes and age. The proportions of oocytes that reached meiosis II (maturation rate) after IVM were 38.6% and 69.2% in the transportation and non-transportation groups, respectively (P = 0.013).

CONCLUSION

In this preliminary study, the usefulness of the transportation of HFF was limited. Further studies on maintaining oocyte normality during transportation are necessary for becoming the effective method for research and clinical use.

In vitro maturation of oocytes from excised ovarian tissue in a patient with autoimmune ovarian insufficiency possibly associated with Epstein-Barr virus infection

BACKGROUND

Some reports show that it is possible to isolate immature oocytes from human ovarian tissue retrieved by a cortex biopsy or ovariectomy of non-stimulated ovaries and mature them in vitro. The mature oocytes can be vitrified and stored for in vitro fertilization, which, along with ovarian tissue cryopreservation, is mostly practiced in young cancer patients to preserve their fertility. There is much less data on this new approach in women with a natural ovarian insufficiency, which can be caused by different factors, including viral infection. In this case report this advanced methodology was used in a young patient suffering from ovarian insufficiency which was possibly associated with Epstein-Barr virus and infectious mononucleosis (glandular fever).

METHODS

This case report included a 27-year-old patient who attended our infertility clinic because of ovarian failure as a part of autoimmune polyendocrinopathy that occurred after Epstein-Barr virus infection, which has rarely been reported until now. Although antral follicles were observed in her ovaries by ultrasound monitoring, she was amenorrhoeic with menopausal concentrations of follicle-stimulating hormone (FSH) and without mature follicles. Therefore, a small biopsy of ovarian cortex tissue was performed using laparoscopy to retrieve immature oocytes. The retrieved oocytes were matured in vitro, cryopreserved, and stored for in vitro fertilization and potential pregnancy.

RESULTS

Four immature, germinal vesicle (GV) oocytes were found and removed from tissue, denuded mechanically by a pipette, and matured in vitro in a maturation medium with added FSH and hCG as well as in co-culture with cumulus cells, which were retrieved by their denudation. Three oocytes matured in vitro to the metaphase II (MII) stage and were vitrified for in vitro fertilization along with ovarian tissue cryopreservation.

CONCLUSION

Our results show that Epstein-Barr infection is possibly associated with autoimmune ovarian failure. The devastating impact on fertility in such disorder can be successfully avoided by in vitro maturation of oocytes from excised ovarian tissue.

Chromatin Accessibility Landscape in Human Early Embryos and Its Association with Evolution

The dynamics of the chromatin regulatory landscape during human early embryogenesis remains unknown. Using DNase I hypersensitive site (DHS) sequencing, we report that the chromatin accessibility landscape is gradually established during human early embryogenesis. Interestingly, the DHSs with OCT4 binding motifs are enriched at the timing of zygotic genome activation (ZGA) in humans, but not in mice. Consistently, OCT4 contributes to ZGA in humans, but not in mice. We further find that lower CpG promoters usually establish DHSs at later stages. Similarly, younger genes tend to establish promoter DHSs and are expressed at later embryonic stages, while older genes exhibit these features at earlier stages. Moreover, our data show that human active transposons SVA and HERV-K harbor DHSs and are highly expressed in early embryos, but not in differentiated tissues. In summary, our data provide an evolutionary developmental view for understanding the regulation of gene and transposon expression.

In vitro maturation of human immature oocytes for fertility preservation and research material

Aim

In recent years, the importance of fertility preservation (FP) has increased. In vitro maturation (IVM), an important technique in FP, has started to be used in the clinic, but controversies persist regarding this technique. Here, a survey of IVM for FP is provided.

Methods

Based on a literature review, the applications of FP, methods of FP, IVM of oocytes that had been collected in vivo and ex vivo, maturation of oocytes after IVM for FP, cryopreservation of oocytes for FP, explanation of the procedures to patients, and recent research on FP using IVM were investigated.

Results

Although IVM for FP remains controversial, the application of FP is expected to expand. Depending on the age and disease status of the patient, various methods of oocyte collection and ovarian stimulation, as well as various needle types and aspiration pressures, have been reported. The maturation rate of IVM in FP ranges widely and requires optimization in the future. In regard to cryopreservation for matured oocytes, the vitrification method is currently recommended.

Conclusion

Regarding FP for patients with cancer, the treatment of cancer is prioritized; thus, the time and use of medicines are often constrained. As several key points regarding IVM remain unclear, well‐designed and specific counseling for patients is necessary.

Vitrification of in vitro matured oocytes collected from surplus ovarian medulla tissue resulting from fertility preservation of ovarian cortex tissue

PURPOSE

The aim of the study was to investigate the maturation rate of immature oocytes collected from ovarian medulla tissue normally discarded during preparation of ovarian cortical tissue for fertility preservation. Further we evaluated survival of derived MII oocytes following vitrification and warming.

METHODS

36 patients aged from 8 to 41 years who had one ovary excised for fertility preservation were included. Oocytes were collected from the medulla tissue and matured in vitro 44-48 h followed by vitrification. Number of oocytes collected, the rates of maturation and post-warming survival were assessed.

RESULTS

On average, 11 immature oocytes were collected per patient. The overall maturation rate was 29 % irrespective of whether the ovary was transported 4-5 h on ice or obtained immediately after oophorectomy. The maturation rate in patients below 20 years of age (55 %) was significantly higher than that of patients aged 20-30 years (29 %) and above 30 years (26 %). The post-warming survival rate was 64 %. No significant relationship was observed between the number of collected oocytes and the age of patients.

CONCLUSIONS

Approximately three MII oocytes were obtained per patient following in vitro maturation (IVM) of immature oocytes collected from medulla tissue, of which two survived vitrification and warming. This approach represents an add-on method to potentially augment the fertility opportunity for cancer patients, especially in young women with cancer where transplantation of cortical tissue may pose a risk of relapse, but the IVM approach is currently too inefficient to be the only method used for fertility preservation.

Novel method for immunofluorescence staining of mammalian eggs using non-contact alternating-current electric-field mixing of microdroplets

Recently, a new technique was developed for non-catalytically mixing microdroplets. In this method, an alternating-current (AC) electric field is used to promote the antigen–antibody reaction within the microdroplet. Previously, this technique has only been applied to histological examinations of flat structures, such as surgical specimens. In this study, we applied this technique for the first time to immunofluorescence staining of three-dimensional structures, specifically, mammalian eggs. We diluted an antibody against microtubules from 1:1,000 to 1:16,000, and compared the chromatic degree and extent of fading across dilutions. In addition, we varied the frequency of AC electric-field mixing from 5 Hz to 46 Hz and evaluated the effect on microtubule staining. Microtubules were more strongly stained after AC electric-field mixing for only 5 minutes, even when the concentration of primary antibody was 10 times lower than in conventional methods. AC electric-field mixing also alleviated microtubule fading. At all frequencies tested, AC electric-field mixing resulted in stronger microtubule staining than in controls. There was no clear difference in a microtubule staining between frequencies. These results suggest that the novel method could reduce antibody consumption and shorten immunofluorescence staining time.

In vitro maturation (IVM) of oocytes recovered from ovariectomy specimens in the laboratory: a promising "ex vivo" method of oocyte cryopreservation resulting in the first report of an ongoing pregnancy in Europe

PURPOSE

We present our center's experience with 34 consecutive cases who underwent in vitro maturation (IVM) of oocytes obtained from ovariectomy specimens and compare our data with updated literature data.

METHODS

Feasibility and efficiency of oocyte collection during ovarian tissue processing was assessed by the recovery rate, maturation rate, and embryological development after IVM.

RESULTS

On average, 14 immature oocytes were retrieved per patient during ovarian tissue processing in 33/34 patients. The overall maturation rate after IVM was 36%. The maturation rate correlated with the age of the patient and the duration of IVM. Predominately, oocyte vitrification was performed. Eight couples preferred embryo cryopreservation. Here, a 65% fertilization rate was obtained and at least one good-quality day 3 embryo was cryopreserved in 7/8 couples. The retrieval of oocytes ex vivo resulted in mature oocytes or embryos available for vitrification in 79% of patients. One patient with ovarian insufficiency following therapeutic embolization of the left uterine and the right ovarian artery because of an arteriovenous malformation had an embryo transfer of one good-quality warmed embryo generated after IVM ex vivo, which resulted in an ongoing clinical pregnancy.

CONCLUSIONS

IVM of oocytes obtained ex vivo during the processing of ovarian cortex prior to cryopreservation is a procedure with emerging promise for patients at risk for fertility loss, as illustrated by the reported pregnancy. However, more data are needed in order to estimate the overall success rate and safety of this novel approach.