Effect of vitrification on mitochondrial membrane potential in human metaphase II oocytes.

OBJECTIVE: The aim of this study was to evaluate the impact of vitrification on mitochondrial membrane potential (ΔΨm) in human metaphase II (MII) oocytes, and the changes of ΔΨm on thawed MII oocytes. METHODS: MII oocytes were obtained from clinical IVF cycles when the oocytes were failed to fertilization within 24 h after insemination. All oocytes were randomly divided into 4 groups: non-frozen (fresh group), cultured for 0 h (0 h group), 2 h (2 h group) and 4 h (4 h group) after vitrification/thawing. All oocytes were stained with the ΔΨm-specific probe JC-1 and detected by laser scanning confocal microscope (LSCM) for mitochondrial analysis. RESULTS: The ΔΨm of oocytes was significantly decreased in 0 h and 2 h groups when compared with fresh group (0.93, 1.09 vs 1.34, P < 0.05), but similar between 4 h group and fresh group (1.30 vs 1.34, P > 0.05). CONCLUSION: In the vitrification/thawing process, the ΔΨm of MII oocytes could have temporally dynamic changes within 2 h after thawing but would be fully recovered after 4 h culture.

High initial FSH dosage reduces the number of available cleavage-stage embryos in a GnRH-antagonist protocol: Real-world data of 8,772 IVF cycles from China.

To evaluate the relationship between the initial follicle stimulating hormone (FSH) dose and the number of available cleavage-stage embryos in in vitro fertilization (IVF) cycles.We included 8772 fresh IVF cycles using a GnRH antagonist protocol at the Genetic and Reproductive Institution of Chongqing, P. R. China, from January 2016 to June 2021.Univariate linear regression was used to evaluate the associations between the initial FSH dosage (≤ 150, 187.5-200, 225, 250, or 300 IU) with the number of available cleavage-stage embryos on day 3. A two-factor linear regression model was applied to calculate the threshold effect of the initial FSH dosage on the number of available cleavage-stage embryos based on a smoothing plot. The initial FSH dose was negatively correlated with the number of available cleavage-stage embryos, independent of female age, body mass index, infertility factors, duration of infertility, anti-Müllerian hormone and basal FSH levels, antral follicle count and the proportions of patients with poor ovarian response or polycystic ovarian syndrome. Using a two-factor linear regression model, we calculated the inflection point to be 200 IU of FSH. The relationship between the initial FSH dose and the number of available cleavage-stage embryos was nonlinear. The initial FSH dose was negatively associated with the number of available cleavage-stage embryos when the initial FSH dose was > 200 IU. Therefore, clinicians should try to avoid unnecessarily increasing the initial FSH dose.

Frozen blastocyst embryo transfer vs. frozen cleavage-stage embryo transfer in couples with recurrent implantation failure: a cohort study.

The objective of this prospective cohort study was to investigate whether cryopreservation of cleavage or blastocyst stage embryos improves in vitro fertilization outcomes in recurrent implantation failure (RIF) patients. The study comprised 575 patients who were allocated to receive either single frozen/thawed blastocyst-stage transfer (SBT) or frozen/thawed double-cleavage-stage embryo transfer (DET). The clinical pregnancy rate, implantation rate, and ongoing pregnancy rate were higher in the SBT group compared with the DET group (41.15% vs. 27.11%, p < 0.001; 41.15% vs. 19.28%, p < 0.001; 40.03% vs. 25.9%, p < 0.001), but the miscarriage rate did not differ between the two groups. It was concluded that frozen/thawed SBT could be a preferred strategy for RIF patients.

Predicting The Developmental Potential Of Cleavage Stage Embryos Based On Oxygen Consumption Rate In FET Cycles.

OBJECTIVE: To study the value of oxygen consumption (OC) as a predictor of the developmental potential of D3 embryos in frozen embryo transfer (FET) cycles. METHODS: This observational study included 148 patients undergoing FET cycles with two embryos transferred per cycle. OC rates were examined by scanning electrochemical microscopy before embryo transfer. Implantation, clinical pregnancy, miscarriage, and live birth rates were calculated. RESULTS: A total of 296 embryos were transferred in 148 cycles, or two embryos per cycle. The embryos were divided into three groups based on OC: Group A included the cases in which the OC rate of each of the two transferred embryos was greater than 3.0 fmol/s; Group B included the cases in which the OC rate of one of the embryos was greater than 3.0 fmol/s and the OC rate of the other embryo was less than 3.0 fmol/s; and Group C included the cases in which the OC rates of the two embryos were less than 3.0 fmol/s. Higher live birth rates and lower miscarriage rates were observed in Group A (p<0.05). CONCLUSIONS: Our data suggest that OC is positively correlated with embryo developmental potential. Therefore, measuring the OC of human embryos may be useful in embryo assessment.

Embryo culture using a time-lapse monitoring system improves live birth rates compared with a conventional culture system: a prospective cohort study.

In this prospective cohort study, the effects of a time-lapse monitoring system on embryo quality and clinical pregnancy outcomes were assessed. A total of 608 patients undergoing in vitro fertilization between April 2013 and June 2014 at our institution were recruited for this study and group-matched into a time-lapse monitoring (TLM) (N = 304) or a standard incubator (SI) (N = 304). The patients' characteristics in the TLM and SI groups were not significantly different. The TLM group showed a significantly higher transferable embryo ratio at Day 3 (61.65% vs. 52.87%; p < 0.0010, RR =1.10 [1.02, 1.19]), a higher number of transferable embryos (4.71 ± 2.38 vs. 4.09 ± 2.35; p = 0.0053, SMD =0.26 [0.06, 0.46]) and number of good-quality embryos cryopreserved at Day 3 (2.72 ± 2.35 vs. 2.11 ± 2.33; p = 0.0056, SMD =0.26 [0.06, 0.46]). In addition, the implantation and clinical pregnancy rates were not statistically significant between the TLM and SI groups. However, the TLM group had a higher ongoing pregnancy rate (67.32% vs. 57.22%; p = 0.0410) and live birth rate (65.37% vs. 55%; p = 0.0380) compared with the SI group. The observed beneficial effects could be the result of a more stable environment provided by the TLM system.

DNA methylation signature of long noncoding RNA genes during human pre-implantation embryonic development.

DNA methylation have crucial roles in regulating the expression of developmental genes during mammalian pre-implantation embryonic development (PED). However, the DNA methylation dynamic pattern of long noncoding RNA (lncRNA) genes, one type of epigenetic regulators, in human PED have not yet been demonstrated. Here, we performed a comprehensive analysis of lncRNA genes in human PED based on public reduced representation bisulphite sequencing (RRBS) data. We observed that both lncRNA and protein-coding genes complete the major demethylation wave at the 2-cell stage, whereas the promoters of lncRNA genes show higher methylation level than protein-coding genes during PED. Similar methylation distribution was observed across the transcription start sites (TSS) of lncRNA and protein-coding genes, contrary to previous observations in tissues. Besides, not only the gamete-specific differentially methylated regions (G-DMRs) but also the embryonic developmental-specific DMRs (D-DMRs) showed more paternal bias, especially in promoter regions in lncRNA genes. Moreover, coding-non-coding gene co-expression network analysis of genes containing D-DMRs suggested that lncRNA genes involved in PED are associated with gene expression regulation through several means, such as mRNA splicing, translational regulation and mRNA catabolic. This firstly provides study provides the methylation profiles of lncRNA genes in human PED and improves the understanding of lncRNA genes involvement in human PED.

[Role of PTEN in mouse pre-implantation development].

The PI3K/Akt signal transduction pathway plays an important role in pre-implantation embryonic development. The tumor suppressor gene PTEN negatively regulates the PI3K/Akt pathway. Although PI3K is constitutively activated during pre-implantation embryonic development, currently no evidence shows the presence and possible involvement of PTEN in early embryo development. We investigated the expression of PTEN protein in germinal vesicle (GV) stage oocytes as well as in pre-implantation embryos. The activated form of PTEN was distributed in the peripheral of GV oocytes and compact morula. Treatment of GV oocytes with PTEN inhibitor bpV(pic) did not affect the maturation of the oocyte, but significantly impaired embryonic development. Thus, our study suggests the necessary role of PTEN in pre-implantation embryonic development.