Early rescue oocyte activation for activation-impaired oocytes with no second polar body extrusion after intracytoplasmic sperm injection

Evaluating the Effectiveness of Assisted Oocyte Activation in ICSI: Pairwise Meta-Analyses and Systematic Evidence Evaluation

BACKGROUND

Artificial oocyte activation (AOA) is used to improve fertilisation rates in intracytoplasmic sperm injection (ICSI) cycles.

OBJECTIVES

To assess the effectiveness of AOA on fertilisation, embryo development, and clinical outcomes, including live birth.

SEARCH STRATEGY

We searched PubMed, Cochrane, and Scopus from January 1990 to March 2024 using terms related to 'artificial oocyte activation' and 'ICSI.'

SELECTION CRITERIA

Study designs included randomised trials (RCTs), quasi-experimental, cohort, and case-control studies that evaluated AOA's effects on ICSI outcomes, provided quantitative data and were published in English.

DATA COLLECTION AND ANALYSIS

Reviewers independently performed data extraction using a standardised form. Study quality was appraised using Joanna Briggs Institute (JBI) Checklists. Meta-analyses employed a random-effects model, and evidence was classified using a comprehensive numerical framework.

MAIN RESULTS

We included 45 studies covering 56 787 mature oocytes, 7463 women for clinical pregnancies, and 7063 women for live births. AOA showed potential in increasing fertilisation rates in patients with a history of low or absent fertilisation but did not enhance embryo development or clinical outcomes. This effect diminished when excluding low-quality studies or focusing solely on RCTs. In other patient groups, AOA showed limited or nonsignificant benefits.

CONCLUSIONS

Applying comprehensive evidence assessment, AOA showed potential in improving fertilisation rates in patients with fertilisation problems but no benefits for embryo development or live birth rates. This underscores the critical importance of rigorous evidence credibility in informing clinical practice in assisted conception.

Early rescue oocyte activation at 5 h post-ICSI is a useful strategy for avoiding unexpected fertilization failure and low fertilization in ICSI cycles

Introduction

Attempts to artificially activate unfertilized oocytes at 24 h post intracytoplasmic sperm injection (ICSI) have generally resulted in poor outcomes. This study aims to explore a new strategy for early judgement and rescue activation of unfertilized oocytes at 5 h post ICSI to avoid unexpected fertilization failure (UFF) or unexpected low fertilization (ULF) in ICSI cycles.

Methods

Firstly, time-lapse data from 278 ICSI cycles were retrospectively analyzed to establish an indicator for fertilization failure prediction. Secondly, 14 UFF and 20 ULF cycles were enrolled for an observational study, early rescue oocyte activation (EROA) was performed on oocytes without post-ICSI Pb2 extrusion to investigate fertilization efficiency, embryo development and clinical outcomes.

Results

The average time to Pb2 extrusion post-ICSI was 3.03±1.21 h, 95.54% of oocytes had extruded Pb2 before 5 h, and the sensitivity and specificity for monitoring Pb2 extrusion at 5 h by time-lapse imaging to predict fertilization were 99.59% and 99.78%, respectively. Early rescue activation of oocytes with no Pb2 extrusion resulted in acceptable fertilization and embryo developmental outcomes, in terms of the fertilization rate (75.00, 72.99%), 2PN fertilization rate (61.36, 56.93%), good-quality embryo rate (42.59, 50.00%), blastocyst formation rate (48.28, 46.03%), good-quality blastocyst rate (34.48, 33.33%), and oocyte utilization rate (36.36, 27.74%), for both UFF and ULF cycles. The clinical pregnancy, embryo implantation, and early miscarriage rates in the rescue oocyte activation group did not significantly differ from those in the Pb2 extrusion group. Fourteen unexpected fertilization failures and 20 low fertilization ICSI cycles were rescued and resulted in clinical pregnancy rates of 40.00% (4/10) and 57.14% (8/14), respectively.

Conclusions

This study demonstrates that monitoring Pb2 extrusion by time-lapse imaging can accurately predict fertilization outcomes, suggesting that early rescue oocyte activation at 5 h post ICSI is an effective strategy for avoiding unexpected fertilization failure and low fertilization in ICSI cycles.

Correlation of DNA fragments with routine semen parameters and lifestyle and their impact on assisted reproductive outcomes

OBJECTIVE

This study investigated the correlation between sperm DNA integrity and routine semen evaluation parameters in male infertile patients, the influencing factors, and the impact of the DNA fragmentation index (DFI) on embryo quality and clinical outcomes in in vitro fertilization and embryo transfer (IVF-ET).

METHODS

Sperm DFI and semen routine parameters of 6160 infertile men admitted between June 2017 and June 2018 were analyzed. Patients were divided into three groups according to their DFI: low-DFI (DFI<15%), medium-DFI (15%<DFI≤30%), and high-DFI (DFI>30%). The correlations of DFI with patients' age, sperm concentration, sperm percentage of forward movement and sperm percentage of normal shape were analyzed. The clinical data of 5040 infertile couples who received IVF treatment between June 2016 and 2021 and had embryos transferred in a fresh cycle were reviewed. The fertilization rate, cleavage rate, blastocyst rate, and pregnancy rate in different DFI groups were compared.

RESULTS

Semen evaluation parameters (concentration, spermatozoa with progressive motility, and the normal morphology rate), the high-quality embryo rate, blastocyst development rate, and pregnancy rate in the high-DFI group were significantly lower than those in the other two groups. The correlation analysis revealed that sperm DFI was negatively correlated with semen concentration, sperm motility, and normal sperm morphology and positively correlated with the man's age, BMI, and unhealthy habits (smoking and drinking). There was no significant difference in the number of mature eggs and normal fertilization rate among groups.

CONCLUSION

A strong correlation exists between sperm DFI and semen evaluation parameters. Smoking, drinking, and other unhealthy habits lead to an increase in DFI, reducing the high-quality embryo rate and blastocyst development rate and affecting pregnancy outcomes.

Novel bi-allelic variants in ACTL7A are associated with male infertility and total fertilization failure

STUDY QUESTION

What are the genetic causes of total fertilization failure (TFF) in a proband suffering from male infertility?

SUMMARY ANSWER

Novel compound heterozygous variants (c.[463C>T];[1084G>A], p.[(Arg155Ter)];[(Gly362Arg)]) in actin-like protein 7A (ACTL7A) were identified as a causative genetic factor for human TFF.

WHAT IS KNOWN ALREADY

ACTL7A, an actin-related protein, is essential for spermatogenesis. ACTL7A variants have been reported to cause early embryonic arrest in humans but have not been studied in human TFF.

STUDY DESIGN, SIZE, DURATION

We recruited a non-consanguineous family whose son was affected by infertility characterized by TFF after ICSI. Whole-exome sequencing was used to identify the potential pathogenic variants. Artificial oocyte activation (AOA) after ICSI was performed to overcome TFF and any resulting pregnancy was followed up.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sanger sequencing was performed to validate the variants. Pathogenicity of the identified variants was predicted by in silico tools. The ultrastructure of spermatozoa was studied by transmission electron microscopy (TEM). Immunofluorescence staining and western blotting were used to investigate the mechanism of the variants on the affected spermatozoa.

MAIN RESULTS AND THE ROLE OF CHANCE

Novel compound heterozygous variants in ACTL7A (c.[463C>T];[1084G>A], p.[(Arg155Ter)];[(Gly362Arg)]) were identified in a family with TFF after ICSI. In silico analysis predicted that the variants lead to a disease-causing protein. TEM showed that the ACTL7A variants caused ultrastructural defects in the acrosome and perinuclear theca. Protein expression of ACTL7A and phospholipase C zeta, a key sperm-borne oocyte activation factor, was significantly reduced in the affected sperm compared to healthy controls, suggesting that the ACLT7A variants lead to an oocyte activation deficiency and TFF. AOA by calcium ionophore (A23187) after ICSI successfully rescued the TFF and achieved a live birth for the patient with ACTL7A variants.

LIMITATIONS, REASONS FOR CAUTION

Given the rarity of sperm-associated TFF, only one family with an only child carrying the ACTL7A variants was found. In addition, the TFF phenotype was not assessed in two or more ICSI cycles, due to the intervention in ICSI with AOA after one failed ICSI cycle. Further studies should validate the ACTL7A variants and its effect on male infertility in larger independent cohorts.

WIDER IMPLICATIONS OF THE FINDINGS

: Our findings revealed a critical role of ACTL7A in male fertility and identified bi-allelic variants in ACTL7A associated with human TFF, which expands the genetic spectrum of TFF and supports the genetic diagnosis of TFF patients. We also rescued TFF by AOA and obtained a healthy live birth, which provides a potentially effective intervention for patients with ACTL7A pathogenic variants.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Natural Science Foundation of China (81971374 and 81401267). No conflicts of interest were declared.

TRIAL REGISTRATION NUMBER

N/A.

The Role of Ca2 + in Maturation and Reprogramming of Bovine Oocytes: A System Study of Low-Calcium Model

[Ca²⁺]_i is essential for mammalian oocyte maturation and early embryonic development, as those processes are Ca²⁺ dependent. In the present study, we investigated the effect of [Ca²⁺]_i on in vitro maturation and reprogramming of oocytes in a lower calcium model of oocyte at metaphase II (MII) stage, which was established by adding cell-permeant Ca²⁺ chelator BAPTA-AM to the maturation medium. Results showed that the extrusion of the first polar body (PB1) was delayed, and oocyte cytoplasmic maturation, including mitochondrial and endoplasmic reticulum distribution, was impaired in lower calcium model. The low-calcium-model oocytes presented a poor developmental phenotype of somatic cell nuclear transfer (SCNT) embryos at the beginning of activation of zygotic genome. At the same time, oxidative stress and apoptosis were observed in the low-calcium-model oocytes; subsequently, an RNA-seq analysis of the lower-calcium-model oocytes screened 24 genes responsible for the poor oocyte reprogramming, and six genes (ID1, SOX2, DPPA3, ASF1A, MSL3, and KDM6B) were identified by quantitative PCR. Analyzing the expression of these genes is helpful to elucidate the mechanisms of [Ca²⁺]_i regulating oocyte reprogramming. The most significant difference gene in this enriched item was ID1. Our results showed that the low calcium might give rise to oxidative stress and apoptosis, resulting in impaired maturation of bovine oocytes and possibly affecting subsequent reprogramming ability through the reduction of ID1.

Ionophore application for artificial oocyte activation and its potential effect on morphokinetics: a sibling oocyte study

PURPOSE

To evaluate whether ionophore application at the oocyte stage changes the morphokinetics of the associated embryos in cases of artificial oocyte activation.

METHODS

In a prospective sibling oocyte approach, 78 ICSI patients with suspected fertilization problems had half of their MII-oocytes treated with a ready-to-use ionophore (calcimycin) immediately following ICSI (study group). Untreated ICSI eggs served as the control group. Primary analyses focused on morphokinetic behavior and the presence of irregular cleavages. The rates of fertilization, utilization, pregnancy, and live birth rate were also evaluated.

RESULTS

Ionophore-treated oocytes showed a significantly earlier formation of pronuclei (t2PNa) and a better synchronized third cell cycle (s3) (P < .05). The rate of irregular cleavage was unaffected (P > .05). Ionophore treatment significantly improved the overall rates of fertilization (P < .01) and blastocyst utilization (P < .05).

CONCLUSION

Ionophore application does not negatively affect cleavage timing nor is it associated with irregular cleavage.