In recent years, postponement of marriage and childbearing in women of reproductive age has led to an increase in the incidence of age-related infertility. The reproductive aging process in women is ...assumed to occur due to a decrease in both the quantity and quality of the oocytes, with the ultimate result being a decline in fecundity. This age-related decline in fecundity is strongly dependent on oocyte quality, which is critical for fertilization and subsequent embryo development. Aged oocytes display increased chromosomal abnormality and dysfunction of cellular organelles, both of which factor into oocyte quality. In particular, mitochondrial dysfunction has been suggested as a major contributor to the reduction in oocyte quality as well as to chromosomal abnormalities in aged oocytes and embryos. Participation of oxidative stress in the oocyte aging process has been proposed because oxidative stress has the capacity to induce mitochondrial dysfunction and directly damage many intracellular components of the oocytes such as lipids, protein, and DNA. In an attempt to improve mitochondrial function in aged oocytes, several therapeutic strategies have been investigated using both animal models and assisted reproductive technology. Here, we review the biological mechanisms and present status of therapeutic strategies in the female reproductive aging field and indicate possible future therapeutic strategies.
Aim
This study aimed to assess the efficacy of the endometrial receptivity array (ERA) as a diagnostic tool and the impact of personalized embryo transfer (pET) for the treatment of patients with ...recurrent implantation failure (RIF) in Japan.
Methods
Fifty patients with a history of RIF with frozen‐thawed blastocyst transfers were recruited from July, 2015 to April, 2016. Endometrial sampling for the ERA and histological dating and a pET according to the ERA were performed. The receptive (R) or non‐receptive (NR) status of the endometrium as a result of the first ERA, endometrial dating, and pregnancy rates after the pET were analyzed.
Results
Of the patients with RIF, 12 (24%) were NR. Among them, eight (66.7%) were prereceptive. A clinical follow‐up was possible in 44 patients who underwent the pET. The pregnancy rates were 58.8% per patient and 35.3% per first pET in the R patients and 50.0% per patient and 50.0% per first pET in the NR patients. Discrepancies between the ERA results and histological dating were seen more in the NR patients than in the R patients.
Conclusions
For patients with unexplained RIF, there is a significance in searching for their personal window of implantation (WOI) using the ERA, considering the percentage of those who were NR and the pregnancy rates that resulted from the pET. By transferring euploid embryos in a personal WOI, much better pregnancy rates are expected.
Oocyte quality is a key factor in determining embryo development; however, we have a poor understanding of what constitutes oocyte quality or the mechanisms governing it. Postovulatory aging of ...oocytes that have not been fertilized for a prolonged time after ovulation is known to significantly impair oocyte quality and subsequent embryo development after fertilization. Embryos derived from postovulatory‐aged oocytes are prone to undergo apoptosis due to the decreased Bcl‐2 expression. Postovulatory aging of oocytes changes the patterns of Ca2+ oscillations at fertilization as a result of impaired Ca2+ regulation in the endoplasmic reticulum. Moreover, postovulatory aging of oocytes impairs mitochondrial adenosine triphosphate production as a result of increasing oxidative stresses. Oxidative stresses also affect intracellular Ca2+ regulation and impair embryo development after fertilization. Collectively, the mechanism of postovulatory oocyte aging might be involved in reactive oxygen species‐induced mitochondrial injury followed by abnormal intracellular Ca2+ regulation in the endoplasmic reticulum.
Background and Aims: Excess lactate in culture medium accumulates may adversely affect the embryo as metabolic stress. The purpose of this study is to investigate whether culture media with a ...low-lactate concentration have an effect on embryonic development in IVF. Method: A split sibling study was performed on 8313 oocytes from 1,312 ICSI cycles from which at least two matured oocytes were retrieved from January 2020 through August 2022. Sperm-injected oocytes were allocated to Continuous Single Culture-NX (NX, N=4352) which contains a low concentration of lactate (1mM) and Global Ⓡ total Ⓡ LP (GL, N=3961), which contains 5mM concentration of lactate. Patients were classified into subgroups of <40 years (854 cycles) and Formula: see text40 years (458 cycles). Single frozen embryo transfers were performed in 859 cycles (NX; N = 500, GL; N = 359). Embryo development up to Day 6, clinical pregnancy and miscarriage rates were compared. Usable blastocysts were defined as any blastocyst cryopreserved on day 5 or day 6. P<0.05 was considered statistically significant. Results: The mean patient age was 37.1 ± 4.4 years. Overall fertilization rates and the blastocyst development rate were significantly higher in NX than GL (80.7% vs. 78.9% and 62.3% vs. 59.8% respectively). There was no significant difference in blastocyst utilization rate on day 5 with all ages considered (36.2% NX vs. 34.2% GL). There was no significant difference in blastocyst development rate for patients Formula: see text40 years, but for patients Formula: see text40 years, blastocyst development rate and day 5 usable blastocyst rate were significantly increased in NX (51.2% vs. 46.4% and 26.2% vs. 22.4% respectively). There were no significant differences in the clinical pregnancy or miscarriage rates (48.8% vs. 49.9% and 22.1% vs. 21.8% respectively). Conclusion: Our results suggest that the lower concentration of lactate in culture medium is effective for late embryonic development in advanced maternal age patients.
The azoospermia factor (AZF) region is important for spermatogenesis, and deletions within these regions are a common cause of oligozoospermia and azoospermia. Although several studies have reported ...this cause, the present research, to the best of our knowledge, is the first large-scale study assessing this factor in Japan. In this study, 1030 male patients with infertility who were examined for Y chromosome microdeletion using the polymerase chain reaction-reverse sequence-specific oligonucleotide (PCR-rSSO) method, a newly developed method for Y chromosome microdeletion screening, were included. The study enrolled 250 patients with severe oligospermia and 717 patients with azoospermia. Among the 1030 patients, 4, 4, 10, and 52 had AZFa, AZFb, AZFb+c, and AZFc deletions, respectively. The sperm recovery rate (SRR) of microdissection testicular sperm extraction in patients with AZFc deletions was significantly higher than that in those without AZF deletions (60.0% vs 28.7%, P = 0.04). In patients with gr/gr deletion, SRR was 18.7%, which was lower than that in those without gr/gr deletion, but was not statistically significant. In conclusion, our study showed that the frequency of Y chromosome microdeletion in male patients in Japan was similar to that reported in patients from other countries, and SRR was higher in patients with AZFc deletion.
We examined whether impairment of intracellular Ca²⁺ homeostasis is related to poor embryo development in in vitro-aged oocytes. We found that in vitro aging of mouse oocytes affected the patterns of ...Ca²⁺ oscillations at fertilization: these Ca²⁺ oscillations were lower in amplitude and higher in frequency compared with oocytes without in vitro aging. We also observed that the intracellular Ca²⁺ store was decreased in in vitro-aged oocytes. A decrease in the Ca²⁺ store induced by thapsigargin, a specific endoplasmic reticulum (ER) membrane Ca²⁺-ATPase inhibitor, resulted in a lower fertilization rate and in poorer embryo development. The frequency of Ca²⁺ oscillations was significantly increased at fertilization, whereas their amplitude was decreased in thapsigargin-treated oocytes. These results suggest that impairment of intracellular Ca²⁺ homeostasis (such as a decrease in the ER Ca²⁺ store) caused an alteration in Ca²⁺ oscillations and the poor embryo development in in vitro-aged oocytes. Because embryo fragmentation is closely related to apoptosis, we examined expression of BAX (a proapototic protein) and BCL2 (an antiapoptotic protein) in in vitro-aged oocytes. Although BCL2 was strongly expressed in oocytes without in vitro aging, expression of BCL2 was significantly reduced in oocytes of other culture conditions and treatments such as those in in vitro aging and those that were pretreated with H₂O₂ or thapsigargin. Acting together, alteration in Ca²⁺ oscillations and decrease in BCL2 expression in in vitro-aged oocytes may lead to poor embryo development.
Abstract
STUDY QUESTION
Does a new system—the chip-sensing embryo respiration monitoring system (CERMs)—enable evaluation of embryo viability for potential application in a clinical IVF setting?
...SUMMARY ANSWER
The system enabled the oxygen consumption rate of spheroids, bovine embryos and frozen-thawed human embryos to be measured, and this rate corresponded to the developmental potential of embryos.
WHAT IS ALREADY KNOWN
To date, no reliable and clinically suitable objective evaluation methods for embryos are available, which circumvent the differences in inter-observer subjective view. Existing systems such as the scanning electrochemical microscopy (SECM) technique, which enables the measurement of oxygen consumption rate in embryos, need improvement in usability before they can be applied to a clinical setting.
STUDY DESIGN, SIZE, DURATION
This is a prospective original research study. The feasibility of measuring the oxygen consumption rate was assessed using CERMs for 9 spheroids, 9 bovine embryos and 30 redundant frozen-thawed human embryos. The endpoints for the study were whether CERMs could detect a dissolved oxygen gradient with high sensitivity, had comparable accuracy to the SECM measuring system with improved usability, and could predict the development of an embryo to a blastocyst by measuring the oxygen consumption rate. The relationship between the oxygen consumption rate and standard morphological evaluation was also examined.
PARTICIPANTS/MATERIALS, SETTING, METHODS
We developed a new CERMs, which enables the oxygen consumption rate to be measured automatically using an electrochemical method. The device was initially used for measuring a dissolved oxygen concentration gradient in order to calculate oxygen consumption rate using nine spheroids. Next, we evaluated data correlation between the CERMs and the SECM measuring systems using nine bovine embryos. Finally, the oxygen consumption rates of 30 human embryos, which were frozen-thawed on 2nd day after fertilization, were measured by CERMs at 6, 24, 48, 72 and 96 h after thawing with standard morphological evaluation. Furthermore, the developed blastocysts were scored using the blastocyst quality score (BQS), and the correlation with oxygen consumption rate was also assessed.
MAIN RESULTS AND THE ROLE OF CHANCE
The device enabled the oxygen consumption rate of an embryo to be measured automatically within a minute. The oxygen concentration gradient profile showed excellent linearity in a distance-dependent change. A close correlation in the oxygen consumption rates of bovine embryos was observed between the SECM measuring system and CERMs, with a determination coefficient of 0.8203 (P = 0.0008). Oxygen consumption rates of human embryos that have reached the blastocyst stage were significantly higher than those of arrested embryos at 48, 72 and 96 h after thawing (P = 0.039, 0.004 and 0.049, respectively). Thus, in vitro development of frozen-thawed human embryos to the blastocyst stage would be predicted at 48 h after thawing (day 4) by measuring the oxygen consumption using CERMs. Although a positive linear relationship between BQS and the oxygen consumption rate was observed the determination coefficient was R2 = 0.6537 (P = 0.008), two blastocysts exhibited low oxygen consumption rates considering their relatively high BQS. This suggests that morphology and metabolism in human embryos might not correlate consistently.
LIMITATIONS, REASONS FOR CAUTION
Transfer of the embryo and pregnancy evaluation was not performed. Thus, a correlation between oxygen consumption and the in vivo viability of embryos remains unknown. Clinical trials, including embryo transfer, would be desirable to determine a threshold value to elect clinically relevant, quality embryos for transfer. We utilized frozen-thawed human embryos in this study. The effect of these manipulations on the respiratory activity of the embryo is also unknown.
WIDER IMPLICATIONS OF THE FINDINGS
Selection of quality embryos, especially in a single embryo transfer cycle, by CERMs may have an impact on obtaining better clinical outcomes, albeit with clinical trials being required. Furthermore, the early determination of quality embryos by CERMs may enable the omission of long-term in vitro embryo culture to the blastocyst stage. CERMs is scalable technology that can be integrated into incubators and/or other embryo evaluation systems, such as the time-lapse systems, due to its chip-based architecture. Thus, CERMS would enable automatic measurement of oxygen consumption, under 5% CO2, in the near future, in order to reduce oxidative stress from exposure to atmospheric air.
STUDY FUNDING/COMPETING INTEREST(S)
This study was supported by grants from the Health and Labor Sciences Research Grant (H24-Hisaichiiki-Shitei-016). The authors have no conflicts of interest.
TRIAL REGISTRATION NUMBER
Not applicable.
Purpose
To investigate whether progestin‐primed ovarian stimulation (PPOS) with chlormadinone acetate (CMA) adversely affects clinical results and neonatal outcomes, or causes congenital deformities.
...Methods
This retrospective study was conducted at private IVF clinic from November 2018 to November 2021. Women underwent oocyte retrieval using gonadotropin‐releasing hormone (GnRH) antagonist protocol (n = 835) or PPOS protocol (n = 57) were included. Eligible patients were normal ovarian responders (aged <40, AMH ≧1.0 ng/mL) with freeze‐all cycle. Embryo developments, clinical results, or neonatal outcomes of singletons derived from transfer of frozen single blastocysts were compared within each group.
Results
Patient characteristics were similar in both groups. The median LH level (mIU/mL) at trigger in the GnRH antagonist group 2.0 (1.2–3.7) was significantly higher than in the PPOS group 0.9 (0.3–1.7). There was no cycle with premature LH surge in the PPOS group. Fertilization and blastocyst formation rates did not differ significantly between groups. Furthermore, clinical outcomes were also similar in the two groups. Congenital abnormality rates did not differ significantly 0.9% (3/329), 0.0% (0/17).
Conclusions
CMA using ovarian stimulation did not negatively affect clinical results. Our data suggest that PPOS with CMA is an appropriate ovarian stimulation method for normal ovarian responders.
Inositol 1,4,5-trisphosphate generated by the action of a phospholipase C (PLC) mediates release of intracellular Ca
2+ that is essential for sperm-induced activation of mammalian eggs. Much ...attention currently focuses on the role of sperm-derived PLCζ in generating changes in egg intracellular Ca
2+ despite the fact that PLCζ constitutes a very small fraction of the total amount of PLC in a fertilized egg. Eggs express several isoforms of PLC, but a role for an egg-derived PLC in sperm-induced Ca
2+ oscillations has not been examined. Reducing egg PLCβ1 by a transgenic RNAi approach resulted in a significant decrease in Ca
2+ transient amplitude, but not duration or frequency, following insemination. Furthermore, overexpressing PLCβ1 by microinjecting a
Plcb1 cRNA significantly perturbed the duration and frequency of Ca
2+ transients and disrupted the characteristic shape of the first transient. These results provide the first evidence for a role of an egg-derived PLC acting in conjunction with a sperm-derived PLCζ in egg activation.
Background: During hormone replacement therapy (HRT) to optimize endometrial growth for thawed-frozen embryo transfer (FET), patients normally undergo estrogen administration for 14 days (day 14 ...group). However, if optimal endometrial thickness is not achieved in 14 days, estrogen treatment is continued for seven more days at a higher dose (day 21 group). This study aimed to determine the effects of this extended estrogen administration regimen on pregnancy outcomes. Methods: A retrospective analysis was performed using our patient database from November 2016 to March 2018. We analyzed 303 cycles of blastocyst-FET and compared patient background characteristics and pregnancy outcomes between day 14 and day 21 groups. Results: In day 21 group, the pregnancy rate tended to be lower while the miscarriage rate and ectopic pregnancy rate were higher than those in day 14 group. However, the differences between the groups were not statistically significant. Conclusions: Delayed endometrial growth resulted in poorer pregnancy outcomes in FET, but the differences were not statistically significant. Thus, it could be meaningful to add estrogen administration for 7 days to avoid the poor outcomes caused by a thin endometrium.
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