Effects of first and second division modes on euploidy acquisition in human embryo

The aim of this study was to non-invasively investigate euploid embryos using methods other than pre-implantation genetic testing for aneuploidy. The study focused on direct cleavage (DC) observed during early embryo development. We also investigated the relationship between the mode of early embryo division and embryo ploidy. Embryos were divided into the normal cleavage (NC) and DC groups, and the DC group was further subdivided into the DC-First (DC-F) and DC-Second (DC-S) groups, depending on whether DC was observed at the first or second cleavage, respectively. The acquisition rates of euploid embryos and embryos appropriate for transfer were compared between the groups. Our results revealed that the timing of the first division did not differ between blastocyst grades or in embryos with varying degrees of ploidy. Further, the timing of the first cleavage did not affect the acquisition rate of embryos appropriate for transfer and euploid embryo formation rate did not significantly differ between the DC and NC groups. We also noted that for embryos appropriate for transfer, euploidy acquisition rate did not differ significantly between the DC and NC groups. Further, the euploidy acquisition rate of embryos did not differ between the DC-F and DC-S groups. However, the acquisition rate of embryos appropriate for transfer, including those with low mosaicism, was significantly higher in the DC-S group than in the DC-F group. These findings indicated that the number of good-quality blastocysts formed was significantly higher in the NC group than in the DC group and the acquisition rate of embryos appropriate for transfer, including those with low mosaicism, was significantly higher in the DC-S group than in the DC-F group.

Original delayed-start ovarian stimulation protocol with a gonadotropin-releasing hormone antagonist, medroxyprogesterone acetate, and high-dose gonadotropin for poor responders and patients with poor-quality embryos

Introduction

The delayed-start gonadotropin-releasing hormone antagonist protocol seems effective for patients who are poor ovarian responders, but there are insufficient data on whether it is also effective for patients with poor-quality embryos and low rates of good blastocyst formation. Specifically, the effectiveness of delayed-start gonadotropin-releasing hormone antagonists with progesterone has not been adequately investigated. Therefore, we compared the efficacy of the original delayed-start gonadotropin-releasing hormone antagonist protocol using medroxyprogesterone acetate (MPA) and high-dose gonadotropin in patients with poor ovarian response.

Methods

Overall, 156 patients with recurrent assisted reproductive technology failure who underwent the original protocol were included. They received cetrorelix acetate (3 mg) and MPA (10 mg) on cycle day 3, and high-dose gonadotropin was initiated on day 11. When the leading follicle reached 14 mm, ganirelix acetate (0.25 mg) was administered until the trigger day. The number of oocytes retrieved, metaphase II (MII) oocytes, two pronuclear (2PN) zygotes, and good blastocysts and live birth rates were compared between the previous (Cycle A) and original (Cycle B) cycles in three groups (Group A, all patients; Group B, poor responders; and Group C, patients with poor-quality embryos).

Results

In Group A (n=156), the number of MII oocytes (3.6 ± 3.3 versus 4.5 ± 3.6), 2PN zygotes (2.8 ± 2.9 versus 3.8 ± 3.1), good blastocysts (0.5 ± 0.9 versus 1.2 ± 1.6), and live birth rates (0.6 versus 24.4) significantly increased in Cycle B. Similar results were obtained in Group B (n=83; 2PN zygotes [1.7 ± 1.7 versus 2.3 ± 1.8], good blastocysts [0.4 ± 0.7 versus 0.9 ± 1.3], live birth rates [0 versus 18.1]) and Group C (n=73; MII oocytes [5.1 ± 3.8 versus 6.6 ± 4.0], 2PN zygotes [4.0 ± 3.4 versus 5.4 ± 3.4], good blastocysts [0.7 ± 1.1 versus 1.6 ± 1.9], and live birth rates [1.4 versus 31.5]).

Conclusion

This original protocol increased the number of MII oocytes retrieved, 2PN zygotes, good blastocysts, and live birth rates in both poor responders and in patients with poor-quality embryos.

Smooth endoplasmic reticulum cluster presence does not affect embryo ploidy

PURPOSE

We examined the impacts of the smooth endoplasmic reticulum cluster (sERC) presence on embryonic development and blastocyst ploidy.

METHODS

Patients who underwent oocyte retrieval from January 2019 to November 2021 were included in the study. We classified the oocytes into three groups: normal oocytes in the sERC ( -) cycle, normal oocytes in the sERC ( +) cycle, and sERC ( +) oocytes. Next, the levels of serum estradiol, progesterone, anti-Mullerian hormone, follicle-stimulating hormone, and human menopausal gonadotropin were compared between the groups. Moreover, fertilization, degeneration, and abnormal fertilization rates were compared between groups. To investigate developmental outcomes, the blastocyst and good-quality blastocyst rates after intracytoplasmic sperm injection were compared. The quality of the transferred blastocysts was evaluated at follow-up. Additionally, embryos were submitted for next-generation sequencing analysis to examine the effect of sERC presence on ploidy.

RESULTS

The sERC ( +) group had significantly higher serum estradiol, serum progesterone, and serum anti-Mullerian hormone concentrations compared to those in the sERC ( -) group (P < 0.01). The abnormal fertilization rate was higher in the sERC ( +) cycle-sERC ( +) oocyte group (16.1%; 37/230) than in the sERC ( +) cycle-normal oocyte (6.2%; 63/971) and sERC ( -) cycle-normal oocyte groups (7.1%; 174/2467) (P < 0.01). After embryo transfer, nine women gave birth, and no confirmed congenital anomalies were observed. There was no significant difference in ploidy between the sERC ( +) and sERC ( -) groups.

CONCLUSION

The occurrence rates of embryos with euploidy were similar between the sERC ( +) and sERC ( -) groups.

P-175 Relationship Between oocytes with sERC and Ploidy

Study question

We investigated the effects of the presence or absence of sERC on subsequent embryonic development and the ploidy of embryos.

Summary answer

The acquisition rates for euploidy embryos were similar to those for the embryos derived from oocytes without smooth endoplasmic reticulum cluster (sERC).

What is known already

The effects of the presence of sERC have been reported on embryonic development processes and pregnancy rate after embryo transfer (ET). In this study, we investigated the effects of the presence of sERC not only on embryonic development and pregnancy rate, but also on the ploidy of embryos from the oocytes with sERC.

Study design, size, duration

The subjects comprised women from whom oocytes were collected from January 2019 to November 2021. The group with the oocytes with sERC was designated as sERC(+), and the other group without sERC as sERC(-).

Participants/materials, setting, methods

Retrospective analysis was performed using a time-lapse system (EmbryoScope+). They were divided into two groups according to the presence of sERC. The groups were compared for fertilization rate, degeneration rate, abnormal fertilization rate (1PN, 3PN, 2.1PN), blastocyst rate, and good-quality-blastocyst rate after ICSI. The prognosis of the transferred embryos was followed up on. In addition, the embryos that were subjected to NGS analysis were investigated for effects of the presence of sERC on their ploidies.

Main results and the role of chance

The sERC(+) group exhibited a significantly lower fertilization rate (74.8%) compared to that of the sERC(-) group (82.4%, P &lt; 0.01). The sERC(+) group exhibited a significantly higher abnormal fertilization rate (14.8%) compared to that of the sERC(-) group (6.6%, P &lt; 0.01). The sERC(+) group showed a significantly higher blastocyst formation rate (57.4%) compared to the sERC(-) group (45.2%, P &lt; 0.01). With respect to after ET prognosis, eight women gave birth with no confirmed congenital anomality. At the very least, the presence of sERC has been shown to have no effect on childbirth. The investigation on ploidy showed that the oocytes in the sERC(+) group included 24.2% euploidy (8/33), 9.1% mosaic (3/33), and 66.7% aneuploidy (22/33) embryos, while the oocytes in the sERC(-) group included 30.4% euploidy (137/451), 12.4% mosaic (56/451), and 57.2% aneuploidy (258/451) embryos. Thus, there was no difference due to the presence of sERC. Three out of the eight euploidy blastocysts in the sERC (+) group had been transferred, one of which reached childbirth.

Limitations, reasons for caution

PGT-A is still under clinical research in Japan.

Wider implications of the findings

Many reports suggested that oocytes with sERC can be used as embryos appropriate for transfer when they develop into blastocysts. The investigation into the ploidy of sERC(+)-derived blastocysts in this study confirmed that the presence of sERC did not affect the ploidy of embryos and that these embryos were transferable.

Trial registration number

not applicable

P-163 Effects of Early Modes of Cell Division on Blastocyst Ploidy

Study question

Abnormal cleavage (AC) has been confirmed at early development. We performed an NGS analysis on AC-derived blastocysts to investigate ploidy of the resulting embryos.

Summary answer

Group in which AC occurred during second division showed significantly higher rates for embryos appropriate for transfer than group where AC occurred during first division.

What is known already

Early division is important in embryogenesis and serves as an indicator of subsequent embryonic development. The occurrence of AC during early development can be identified with the advent of the time-lapse incubator, which in turn has led to difficulties in determining whether such AC-derived blastocysts can be used embryo transfer. In this study, we performed NGS analysis on AC-derived blastocysts to investigate the ploidy of the resulting embryos.

Study design, size, duration

The subjects comprised women from whom oocytes were collected for NGS analysis from January 2019 to November 2021. Retrospective analysis was performed using a time-lapse system (EmbryoScope+). Embryos were categorized into two groups: those with abnormal divisions observed during the first and second divisions and those in which normal divisions were observed in the same cycle.

Participants/materials, setting, methods

The group with AC observed was designated the AC group and the other with normal divisions as the Normal Cleavage (NC) group. Within the AC group, the subgroup with AC observed during first division was designated as the First (AC-F) group and the subgroup with AC observed during second division as the Second (AC-S) group for comparing the acquisition rates for euploidy embryos and embryos appropriate for transfer.

Main results and the role of chance

The AC group (17.3%) showed a significantly lower rate of good blastocyst formation than did the NC group (53.4%) (P &lt; 0.01). The cutoff point for mosaicism was defined as &gt; 20% of abnormal cells. Percentage &lt;20 were classified as normal (euploid); &gt;80, abnormal (aneuploidy); and 20-80, mosaic. Using a cutoff of 50% to differentiate ‘‘low’’ mosaics from ‘‘high’’ mosaics. There was no difference between the two groups in the acquisition rates for euploidy embryos (30.8-35.1%) and the embryos appropriate for transfer, including low-mosaic ones (44.3-46.1%). There also was no difference in the acquisition rates for euploidy embryos (24.0-37.0%) between the AC-F and AC-S groups. However, the AC-S group (59.3%) showed significantly higher acquisition rates than the AC-F group (32.0%) for the embryos appropriate for transfer, including low-mosaic ones (P &lt; 0.05).

Limitations, reasons for caution

PGT-A is still under clinical research in Japan.

Wider implications of the findings

The group in which AC occurred during second division showed significantly higher acquisition rates for the embryos appropriate for transfer than the group in which AC occurred during first division. This indicates that the most important factor for identifying euploidy embryos is going through the two-cell phase during first division.

Trial registration number

not applicable

The effects of differences in trophectoderm biopsy techniques and the number of cells collected for biopsy on next‐generation sequencing results

Purpose

To examine how differences in trophectoderm biopsy techniques affect the frequency of mosaic embryos and sequencing results.

Methods

We examined differences in next‐generation sequencing (NGS) analysis results among operators or according to biopsy technique. Additionally, we determined the cut‐off for the number of collected cells to predict the occurrence of mosaicism. We collected cells according to the cut‐off value and examined whether there was a difference in the NGS analysis results between the pulling and flicking methods.

Results

There was no difference in the NGS analysis results among the operators. Regarding re‐biopsy, changes in the mosaic were observed in all specimens. The cut‐off value for the number of collected cells was five, and when more than five cells were collected, there was no difference in the NGS analysis results between the two methods.

Conclusions

We demonstrated that if trophectoderm biopsy techniques and NGS are stable, the cell collection location has a greater effect on NGS results than the biopsy technique.

A novel trophectoderm biopsy technique for all blastocyst stages

Purpose

This study was conducted to assess the effectiveness of a new trophectoderm (TE) biopsy method that does not require prior opening of the zona pellucida at the blastocyst stage.

Methods

TE biopsy was conducted using a modified extrusion method for embryos during the cleavage stage. In this method, culture medium was injected into the perivitelline space to help extrude TE cells from the zona pellucida before TE biopsy.

Results

Our extrusion method preserves the embryo culture environment until immediately before biopsy because it does not require opening of the zona pellucida prior to TE biopsy. Furthermore, this method does not require a waiting time for blastocyst hatching after laser irradiation, thereby minimizing damage to the embryos and maintaining the time schedule of culture operations.

Conclusions

TE biopsy using this novel extrusion method may be useful in various applications, including the collection of TE cells for next‐generation sequencing analysis.

The effect of repeated cryopreservation and thawing using cryotip on the clinical outcomes of embryos

PURPOSE

To compare the clinical outcomes of embryo transfers that were cryopreserved and thawed two or three times with those cryopreserved and thawed once by CryoTip.

METHODS

Data for 388 single cryopreserved-thawed blastocyst transfer cycles, performed from April 2012 to March 2014, were assessed. The blastocysts were classified into three groups: blastocysts (A) cryopreserved once, (B) cryopreserved twice, and (C) cryopreserved three times.

RESULTS

The pregnancy rate was 43.8% (134/306) in group A and 46.3% (38/82) in group B, while the miscarriage rate was 29.1% (39/134) in group A and 23.7% (9/38) in group B. The rate of improvement/maintenance of blastocyst grade was 84.0% (257/306) in group A and 80.5% (66/82) in group B. The pregnancy and miscarriage rates of the blastocysts that showed improvement/maintenance in the grade were 45.9% (118/257) and 29.7% (35/118) in group A and 48.5% (32/66) and 21.9% (7/32) in group B, respectively. The pregnancy rate was 33.3% (2/6), while the miscarriage rate was 0.0% (0/2) in group C.

CONCLUSIONS

Pregnancy rates achieved with re-cryopreserved and rethawed blastocyst transfer were comparable to those achieved with single cryopreserved-thawed blastocyst transfer.