Complete oocyte activation failure after ICSI can be overcome by a modified injection technique

Good practice recommendations on add-ons in reproductive medicine†

STUDY QUESTION

Which add-ons are safe and effective to be used in ART treatment?

SUMMARY ANSWER

Forty-two recommendations were formulated on the use of add-ons in the diagnosis of fertility problems, the IVF laboratory and clinical management of IVF treatment.

WHAT IS KNOWN ALREADY

The innovative nature of ART combined with the extremely high motivation of the patients has opened the door to the wide application of what has become known as 'add-ons' in reproductive medicine. These supplementary options are available to patients in addition to standard fertility procedures, typically incurring an additional cost. A diverse array of supplementary options is made available, encompassing tests, drugs, equipment, complementary or alternative therapies, laboratory procedures, and surgical interventions. These options share the common aim of stating to enhance pregnancy or live birth rates, mitigate the risk of miscarriage, or expedite the time to achieving pregnancy.

STUDY DESIGN, SIZE, DURATION

ESHRE aimed to develop clinically relevant and evidence-based recommendations focusing on the safety and efficacy of add-ons currently used in fertility procedures in order to improve the quality of care for patients with infertility.

PARTICIPANTS/MATERIALS, SETTING, METHODS

ESHRE appointed a European multidisciplinary working group consisting of practising clinicians, embryologists, and researchers who have demonstrated leadership and expertise in the care and research of infertility. Patient representatives were included in the working group. To ensure that the guidelines are evidence-based, the literature identified from a systematic search was reviewed and critically appraised. In the absence of any clear scientific evidence, recommendations were based on the professional experience and consensus of the working group. The guidelines are thus based on the best available evidence and expert agreement. Prior to publication, the guidelines were reviewed by 46 independent international reviewers. A total of 272 comments were received and incorporated where relevant.

MAIN RESULTS AND THE ROLE OF CHANCE

The multidisciplinary working group formulated 42 recommendations in three sections; diagnosis and diagnostic tests, laboratory tests and interventions, and clinical management.

LIMITATIONS, REASONS FOR CAUTION

Of the 42 recommendations, none could be based on high-quality evidence and only four could be based on moderate-quality evidence, implicating that 95% of the recommendations are supported only by low-quality randomized controlled trials, observational data, professional experience, or consensus of the development group.

WIDER IMPLICATIONS OF THE FINDINGS

These guidelines offer valuable direction for healthcare professionals who are responsible for the care of patients undergoing ART treatment for infertility. Their purpose is to promote safe and effective ART treatment, enabling patients to make informed decisions based on realistic expectations. The guidelines aim to ensure that patients are fully informed about the various treatment options available to them and the likelihood of any additional treatment or test to improve the chance of achieving a live birth.

STUDY FUNDING/COMPETING INTEREST(S)

All costs relating to the development process were covered from ESHRE funds. There was no external funding of the development process or manuscript production. K.L. reports speakers fees from Merck and was part of a research study by Vitrolife (unpaid). T.E. reports consulting fees from Gynemed, speakers fees from Gynemed and is part of the scientific advisory board of Hamilton Thorne. N.P.P. reports grants from Merck Serono, Ferring Pharmaceutical, Theramex, Gedeon Richter, Organon, Roche, IBSA and Besins Healthcare, speakers fees from Merck Serono, Ferring Pharmaceutical, Theramex, Gedeon Richter, Organon, Roche, IBSA and Besins Healthcare. S.R.H. declares being managing director of Fertility Europe, a not-for-profit organization receiving financial support from ESHRE. I.S. is a scientific advisor for and has stock options from Alife Health, is co-founder of IVFvision LTD (unpaid) and received speakers' fee from the 2023 ART Young Leader Prestige workshop in China. A.P. reports grants from Gedeon Richter, Ferring Pharmaceuticals and Merck A/S, consulting fees from Preglem, Novo Nordisk, Ferring Pharmaceuticals, Gedeon Richter, Cryos and Merck A/S, speakers fees from Gedeon Richter, Ferring Pharmaceuticals, Merck A/S, Theramex and Organon, travel fees from Gedeon Richter. The other authors disclosed no conflicts of interest.

DISCLAIMER

This Good Practice Recommendations (GPRs) document represents the views of ESHRE, which are the result of consensus between the relevant ESHRE stakeholders and are based on the scientific evidence available at the time of preparation.ESHRE GPRs should be used for information and educational purposes. They should not be interpreted as setting a standard of care or bedeemedinclusive of all proper methods of care, or be exclusive of other methods of care reasonably directed to obtaining the same results.Theydo not replace the need for application of clinical judgement to each individual presentation, or variations based on locality and facility type.Furthermore, ESHRE GPRs do not constitute or imply the endorsement, or favouring, of any of the included technologies by ESHRE.

Advances in the study of genetic factors and clinical interventions for fertilization failure

Fertilization failure refers to the failure in the pronucleus formation, evaluating 16-18 h post in vitro fertilization or intracytoplasmic sperm injection. It can be caused by sperm, oocytes, and sperm-oocyte interaction and lead to great financial and physical stress to the patients. Recent advancements in genetics, molecular biology, and clinical-assisted reproductive technology have greatly enhanced research into the causes and treatment of fertilization failure. Here, we review the causes that have been reported to lead to fertilization failure in fertilization processes, including the sperm acrosome reaction, penetration of the cumulus and zona pellucida, recognition and fusion of the sperm and oocyte membranes, oocyte activation, and pronucleus formation. Additionally, we summarize the progress of corresponding treatment methods of fertilization failure. This review will provide the latest research advances in the genetic aspects of fertilization failure and will benefit both researchers and clinical practitioners in reproduction and genetics.

The Therapeutic and Diagnostic Potential of Phospholipase C Zeta, Oocyte Activation, and Calcium in Treating Human Infertility

Oocyte activation, a fundamental event during mammalian fertilisation, is initiated by concerted intracellular patterns of calcium (Ca2+) release, termed Ca2+ oscillations, predominantly driven by testis-specific phospholipase C zeta (PLCζ). Ca2+ exerts a pivotal role in not just regulating oocyte activation and driving fertilisation, but also in influencing the quality of embryogenesis. In humans, a failure of Ca2+ release, or defects in related mechanisms, have been reported to result in infertility. Furthermore, mutations in the PLCζ gene and abnormalities in sperm PLCζ protein and RNA, have been strongly associated with forms of male infertility where oocyte activation is deficient. Concurrently, specific patterns and profiles of PLCζ in human sperm have been linked to parameters of semen quality, suggesting the potential for PLCζ as a powerful target for both therapeutics and diagnostics of human fertility. However, further to PLCζ and given the strong role played by Ca2+ in fertilisation, targets down- and up-stream of this process may also present a significantly similar level of promise. Herein, we systematically summarise recent advancements and controversies in the field to update expanding clinical associations between Ca2+-release, PLCζ, oocyte activation and human fertility. We discuss how such associations may potentially underlie defective embryogenesis and recurrent implantation failure following fertility treatments, alongside potential diagnostic and therapeutic avenues presented by oocyte activation for the diagnosis and treatment of human infertility.

How to improve the clinical outcome of round spermatid injection (ROSI) into the oocyte: Correction of epigenetic abnormalities

Background

First successful human round spermatid injection (ROSI) was conducted by Tesarik et al. in 1996 for the sole treatment of nonobstructive azoospermic men whose most advanced spermatogenic cells were elongating round spermatids. Nine offsprings from ROSI were reported between 1996 and 2000. No successful deliveries were reported for 15 years after that. Tanaka et al. reported 90 babies born after ROSI and their follow-up studies in 2015 and 2018 showed no significant differences in comparison with those born after natural conception in terms of physical and cognitive abilities. However, clinical outcomes remain low.

Method

Clinical and laboratory data of successful cases in the precursor ROSI groups and those of Tanaka et al. were reviewed.

Results

Differences were found between the two groups in terms of identification of characteristics of round spermatid and oocyte activation. Additionally, epigenetic abnormalities were identified as underlying causes for poor ROSI results, besides correct identification of round spermatid and adequate oocyte activation. Correction of epigenetic errors could lead to optimal embryonic development.

Conclusion

Correction of epigenetic abnormalities has a probability to improve the clinical outcome of ROSI.

Artificial oocyte activation with ionomycin compared with A23187 among patients at risk of failed or impaired fertilization

RESEARCH QUESTION

Do fertilization rates differ between intracytoplasmic sperm injection (ICSI) cycles treated with artificial oocyte activation (AOA) using 10 µmol/l ionomycin or commercial A23187 in women at risk of failed or impaired fertilization?

DESIGN

This single-centre, 7-year retrospective cohort study included 157 couples with a history of total fertilization failure (TFF, 0%) or low fertilization (<30%) after ICSI, or with severe oligo-astheno-teratozoospermia (OAT) in the male partner. Couples and underwent 171 ICSI-AOA cycles using either 10 µmol/l ionomycin or commercial A23187. The embryological and clinical outcomes were compared.

RESULTS

Fertilization rates in the ionomycin group were significantly higher than those in the A23187 group for all three subgroups (TFF, 46.9% versus 28.4%, P = 0.002; low fertilization, 67.7% versus 49.2%, P < 0.001; severe OAT, 66.4% versus 31.6%, P < 0.001). AOA with ionomycin significantly increased the day 3 cleavage rate (P = 0.009) when compared with A23187 in the low fertilization group, but not in the TFF or severe OAT group (both P > 0.05). The rates of day 3 good-quality embryos, clinical pregnancy, implantation and live birth, and the cumulative live birth, did not differ between the two groups (all P > 0.05). A total of 64 live births resulted in 72 healthy babies born.

CONCLUSIONS

AOA with 10 µmol/l ionomycin may be more effective than commercial A23187 in improving oocyte activation in patients at risk of failed or impaired fertilization, especially in cases of sperm-related defects.

Embryo development and live birth resulted from artificial oocyte activation after microdissection testicular sperm extraction with ICSI in patients with non-obstructive azoospermia

INTRODUCTION

The application of microdissection testicular sperm extraction (micro-TESE) to retrieve the sperm of patients with non-obstructive azoospermia (NOA) has greatly increased. Patients with NOA often have poor quality sperm. Unfortunately, there are few studies on artificial oocyte activation (AOA) performed on patients who successfully retrieved motile and immotile sperm by micro-TESE after intracytoplasmic sperm injection (ICSI). Therefore, this study sought to obtain more comprehensive evidence-based data and embryo development outcomes to aid consultation of patients with NOA who opted to receive assisted reproductive techniques and to determine whether AOA needs to be performed in different motile sperm after ICSI.

METHODS

This retrospective study involved 235 patients with NOA who underwent micro-TESE to retrieve adequate sperm for ICSI between January 2018 and December 2020. A total of 331 ICSI cycles were performed in the 235 couples. Embryological, clinical, and neonatal outcomes were demonstrated comprehensively between motile sperm and immotile sperm using AOA and non-AOA treatment.

RESULTS

Motile sperm injection with AOA (group 1) showed significantly higher fertility rate (72.77% vs. 67.59%, p=0.005), 2 pronucleus (2PN) fertility rate (64.33% vs. 60.22%, p=0.036), and miscarriage rate (17.65% vs. 2.44%, p=0.018) compared with motile sperm injection with non-AOA (group 2). Group 1 had comparable available embryo rate (41.29% vs. 40.74%, p=0.817), good embryo rate (13.44% vs. 15.44%, p=0.265), and without an embryo for transfer rate (10.85% vs. 9.90%, p=0.815) compared with group 2. Immotile sperm injection with AOA (group 3) displayed significantly higher fertility rate (78.56% vs. 67.59%, p=0.000), 2PN fertility rate (67.36% vs. 60.22%, p=0.001), without an embryo for transfer rate (23.76% vs. 9.90%, p=0.008), and miscarriage rate (20.00% vs. 2.44%, p=0.014), but significantly lower available embryo rate (26.63% vs.40.74%, p=0.000) and good embryo rate (15.44% vs. 6.99%, p=0.000) compared with group 2. In groups 1, 2, and 3, the rates of implantation (34.87%, 31.85% and 28.00%, respectively; p=0.408), clinical pregnancy (43.87%, 41.00%, and 34.48%, respectively; p=0.360) and live birth (36.13%, 40.00%, and 27.59%, respectively; p=0.194) were similar.

DISCUSSION

For those patients with NOA from whom adequate sperm were retrieved for ICSI, AOA could improve fertilization rate, but not embryo quality and live birth outcomes. For patients with NOA and only immotile sperm, AOA can help achieve acceptable fertilization rate and live birth outcomes. AOA is recommended for patients with NOA only when immotile sperm are injected.

Is there any effect on imprinted genes H19, PEG3, and SNRPN during AOA?

Assisted oocyte activation (AOA) has been proposed as an effective technique to overcome the problem of impaired fertilization after intracytoplasmic sperm injection (ICSI) but the safety of AOA remains a concern. We aimed to investigate if AOA induces imprinting effects on embryos. We used 13 cleavage embryos, nine blastocysts, and eight placentas from 15 patients. The subjects were divided into six groups by tissue type and with or without AOA. The methylation levels of imprinted genes (H19, paternally expressed gene [PEG3] and small nuclear ribonucleoprotein polypeptide N [SNRPN]) were tested by pyrosequencing. We observed different methylation levels among cleavage embryos. The variability was much more remarkable between cleavage embryos than blastocysts and placenta tissues. The methylation levels were especially higher in SNRPN and lower in the H19 gene in AOA embryos than those without AOA. No significant difference was found either among blastocysts or among placenta tissues regardless of AOA. The methylation levels of the three genes in blastocysts were very similar to those in the placenta. Compared to conventional ICSI, AOA changed imprinting methylation rates at H19 and SNRPN in cleavage embryos but not in the blastocyst stage and placenta. We recommend that blastocyst transfer should be considered for patients undergoing AOA during in vitro fertilization.

OUP accepted manuscript

BACKGROUND

Oocyte activation deficiency (OAD) is attributed to the majority of cases underlying failure of ICSI cycles, the standard treatment for male factor infertility. Oocyte activation encompasses a series of concerted events, triggered by sperm-specific phospholipase C zeta (PLCζ), which elicits increases in free cytoplasmic calcium (Ca²⁺) in spatially and temporally specific oscillations. Defects in this specific pattern of Ca²⁺ release are directly attributable to most cases of OAD. Ca²⁺ release can be clinically mediated via assisted oocyte activation (AOA), a combination of mechanical, electrical and/or chemical stimuli which artificially promote an increase in the levels of intra-cytoplasmic Ca²⁺. However, concerns regarding safety and efficacy underlie potential risks that must be addressed before such methods can be safely widely used.

OBJECTIVE AND RATIONALE

Recent advances in current AOA techniques warrant a review of the safety and efficacy of these practices, to determine the extent to which AOA may be implemented in the clinic. Importantly, the primary challenges to obtaining data on the safety and efficacy of AOA must be determined. Such questions require urgent attention before widespread clinical utilization of such protocols can be advocated.

SEARCH METHODS

A literature review was performed using databases including PubMed, Web of Science, Medline, etc. using AOA, OAD, calcium ionophores, ICSI, PLCζ, oocyte activation, failed fertilization and fertilization failure as keywords. Relevant articles published until June 2019 were analysed and included in the review, with an emphasis on studies assessing large-scale efficacy and safety.

OUTCOMES

Contradictory studies on the safety and efficacy of AOA do not yet allow for the establishment of AOA as standard practice in the clinic. Heterogeneity in study methodology, inconsistent sample inclusion criteria, non-standardized outcome assessments, restricted sample size and animal model limitations render AOA strictly experimental. The main scientific concern impeding AOA utilization in the clinic is the non-physiological method of Ca²⁺ release mediated by most AOA agents, coupled with a lack of holistic understanding regarding the physiological mechanism(s) underlying Ca²⁺ release at oocyte activation.

LIMITATIONS, REASONS FOR CAUTION

The number of studies with clinical relevance using AOA remains significantly low. A much wider range of studies examining outcomes using multiple AOA agents are required.

WIDER IMPLICATIONS

In addition to addressing the five main challenges of studies assessing AOA safety and efficacy, more standardized, large-scale, multi-centre studies of AOA, as well as long-term follow-up studies of children born from AOA, would provide evidence for establishing AOA as a treatment for infertility. The delivery of an activating agent that can more accurately recapitulate physiological fertilization, such as recombinant PLCζ, is a promising prospect for the future of AOA. Further to PLCζ, many other avenues of physiological oocyte activation also require urgent investigation to assess other potential physiological avenues of AOA.

STUDY FUNDING/COMPETING INTERESTS

D.G. was supported by Stanford University’s Bing Overseas Study Program. J.K. was supported by a Healthcare Research Fellowship Award (HF-14-16) made by Health and Care Research Wales (HCRW), alongside a National Science, Technology, and Innovation plan (NSTIP) project grant (15-MED4186-20) awarded by the King Abdulaziz City for Science and Technology (KACST). The authors have no competing interests to declare.

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.

Gonadotropin levels at the start of ovarian stimulation predict normal fertilization after hCG re-trigger in GnRH antagonist cycles

PURPOSE

To assess the appropriateness of human chorionic gonadotropin (hCG) re-trigger in poor responders to gonadotropin-releasing hormone agonist (GnRHa) trigger in controlled ovarian stimulation (COS) cycles.

METHODS

The 2251 cycles in 2251 patients triggered with GnRHa for oocyte stimulation, with or without requiring hCG re-trigger between 2013 and 2018, were retrospectively analyzed to compare gonadotropin levels at the start of COS and the rate of normal fertilization between the re-trigger and non-re-trigger group. Furthermore, patients in the re-trigger group were stratified by the rate of normal fertilization (good: ≥60% or poor: <60%) to compare patient demographics, hormone profiles, and clinical outcome between the subgroups.

RESULTS

In the re-trigger group, FSH and LH levels at the start of COS were significantly lower in the good fertilization group than in the poor fertilization group (P < .01). Receiver operating characteristic curves identified cutoff values of the FSH and LH levels of 1.30 and 0.35 mIU/mL, respectively, for predicting ≥60% normal fertilization.

CONCLUSION

Gonadotropin levels at the start of COS are predictors of response to GnRHa trigger and hCG re-trigger necessity, and may serve as indicators to help clinicians appropriately choose hCG re-trigger rather than abandoning the cycles or continuing the first oocyte aspiration attempt.

Diagnosis and Treatment of Male Infertility-Related Fertilization Failure

Infertility affects approximately 15% of reproductive-aged couples worldwide, of which up to 30% of the cases are caused by male factors alone. The origin of male infertility is mostly attributed to sperm abnormalities, of which many are caused by genetic defects. The development of intracytoplasmic sperm injection (ICSI) has helped to circumvent most male infertility conditions. However, there is still a challenging group of infertile males whose sperm, although having normal sperm parameters, are unable to activate the oocyte, even after ICSI treatment. While ICSI generally allows fertilization rates of 70 to 80%, total fertilization failure (FF) still occurs in 1 to 3% of ICSI cycles. Phospholipase C zeta (PLCζ) has been demonstrated to be a critical sperm oocyte activating factor (SOAF) and the absence, reduced, or altered forms of PLCζ have been shown to cause male infertility-related FF. The purpose of this review is to (i) summarize the current knowledge on PLCζ as the critical sperm factor for successful fertilization, as well as to discuss the existence of alternative sperm-induced oocyte activation mechanisms, (ii) describe the diagnostic tests available to determine the cause of FF, and (iii) summarize the beneficial effect of assisted oocyte activation (AOA) to overcome FF.

Reduction of truncated Kit Expression in Men with Abnormal Semen Parameters, Globozoospermia and History of Low or Fertilization Failure

Objective

Phospholipase C zeta 1 (PLCζ) is one of the main sperm factor involved in oocyte activation and other factors may assist this factor to induce successful fertilization. Microinjection of recombinant tr-kit, a truncated form of c-kit receptor, into metaphase II-arrested mouse oocytes initiate egg activation. Considering the potential roles of tr- KIT during spermiogenesis and fertilization, we aimed to assess expression of tr-KIT in sperm of men with normal and abnormal parameters and also in infertile men with previous failed fertilization and globozoospermia.

Materials and Methods

This experimental study was conducted from September 2015 to July 2016 on 30 normozoospermic and 20 abnormozoospermic samples for experiment one, and also was carried out on 10 globozoospermic men, 10 men with a history low or failed fertilization and 13 fertile men for experiment two. Semen parameters and sperm DNA fragmentation were assessed according to WHO protocol, and TUNEL assay. Sperm tr- KIT was evaluated by flow cytometry, immunostaining and western blot.

Results

The results show that tr-KIT mainly was detected in post-acrosomal, equatorial and tail regions. Percentage of tr-KIT-positive spermatozoa in abnormozoospermic men was significantly lower than normozoospermic men. Also significant correlations were observed between sperm tr-KIT with sperm count (r=0.8, P<0.001), motility (r=0.31, P=0.03) and abnormal morphology (r=-0.6, P<0.001). Expression of tr-KIT protein was significantly lower in infertile men with low/ failed fertilization and globozoospermia compared to fertile men. The significant correlation was also observed between tr-KIT protein with fertilization rate (r=-0.46, P=0.04). In addition, significant correlations were observed between sperm DNA fragmentation with fertilization rate (r=-0.56, P=0.019) and tr-KIT protein (r=-0.38, P=0.04).

Conclusion

tr-KIT may play a direct or indirect role in fertilization. Therefore, to increase our insight regarding the role of tr-KIT in fertilization further research is warranted.

A novel mutation in the TUBB8 gene is associated with complete cleavage failure in fertilized eggs

PURPOSE

Cleavage of the zygote during human reproduction is a key event of early embryonic development. The genetic events associated with idiopathic embryonic cleavage failure are not certain. Mutations in the tubulin beta 8 class VIII (TUBB8) gene have been reported to be associated with oocyte maturation, fertilization, and developmental arrest. Here, we aimed to assess the clinical and genetic characteristics of complete cleavage failure in fertilized eggs.

METHODS

We have characterized a patient with a 9-year history of primary infertility in a non-consanguineous family from China. The patient presented complete cleavage failure in all two-pronuclear (2PN) fertilized oocytes after 2 cycles of in vitro fertilization (IVF). We performed Sanger sequencing of the TUBB8 gene in the patient, and further bioinformatics analysis to identify pathogenesis of gene.

RESULTS

A novel homozygous mutation, c.322G > A (p.Glu108Lys), was detected, and this change was absent from 179 control subjects. Glutamic acid is highly conserved at this position, and replacement by lysine was predicted to be repelled by the α-tubulin positive region, disrupting the α-β tubulin interaction.

CONCLUSIONS

Our findings presented a homozygous mutation of TUBB8 associated with complete cleavage failure in fertilized eggs and provided new data for the genotype-phenotype of TUBB8-related diseases.

Artificial oocyte activation with calcium ionophore for frozen sperm cycles

Fertilization problems are the major problems that may be faced in 30-55% of the patients during an intracytoplasmic sperm injection (ICSI) cycle. A successful oocyte activation depends on factors related to both sperm and oocyte, and one of the important factors that mediates the process is Ca²⁺ concentration within the oocyte. Artificial oocyte activation (AOA) is a method used for fertilization problems that commonly involve the usage of Ca²⁺ ionophores and is usually used in problems such as total fertilization failure (TFF) and globozoospermia. The aim of the present study was to investigate possible effects of AOA for different groups of patients with fertilization failure. Four groups of patients (previous TFF, low oocyte number, severe sperm quality, and frozen sperm (FS) group) that underwent ICSI with AOA were included in the study. All groups had similar control groups with same indications except TFF, where AOA was not performed. Fertilization rates were significantly higher in the TFF group than those observed in other AOA groups. Fertilization rates and quality of embryos observed in the remaining AOA groups were higher than those of the controls, which were statistically insignificant. Prgenancy rates were higher in all AOA groups compared to the controls, although the differences were significant in FS group only. Quality of embryos and pregnancy rates were lower in the TFF group compared to the remaining AOA groups indicating possible concomitant problems. Fertilization rates, quality of embryos and pregnancy rates seemed to be increased in all indication groups suggesting that not only TFF patients but also a wide variety of patients with different indications may benefit from AOA.

ABBREVIATIONS

ICSI: Intracytoplasmic sperm injection; ARTs: Assisted reproductive techniques; Ca: Calcium; AOA: Artificial oocyte activation; TFF: Total fertilization failures; OAT: Oligoasthenoteratozoospemia; IVF: In vitro fertilization; SOAT: Severe OAT; LON: Low ooctye number; FS: Frozen sperm; hCG: human chorionic gonadotrophin; PVP: polyvinylpyrrolidone; HSA: human serum albumin.

Dehydroepiandrosterone (DHEA) and Its Sulfate (DHEA-S) in Mammalian Reproduction: Known Roles and Novel Paradigms

Steroid hormones form an integral part of normal development in mammalian organisms. Cholesterol is the parent compound from which all steroid hormones are synthesized. The product pregnenolone formed from cholesterol serves as precursor for mineralocorticoids, glucocorticoids, as well as dehydroepiandrosterone (DHEA) and its derived sexual hormones. DHEA assumes the prohormone status of a predominant endogenous precursor and a metabolic intermediate in ovarian follicular steroidogenesis. DHEA supplementation has been used to enhance ovarian reserve. Steroids like estradiol and testosterone have long been contemplated to play important roles in regulating meiotic maturation of oocytes in conjunction with gonadotropins. It is known that oocyte priming with estrogen is necessary to develop calcium (Ca²⁺) oscillations during maturation. Accruing evidence from diverse studies suggests that DHEA and its sulfate (dehydroepiandrosterone sulfate, DHEA-S) play significantly vital role not only as intermediates in androgen and estrogen formation, but may also be the probable 'oocyte factor' and behave as endogenous agonists triggering calcium oscillations for oocyte activation. DHEA/DHEA-S have been reported to regulate calcium channels for the passage of Ca²⁺ through the oocyte cytoplasm and for maintaining required threshold of Ca²⁺ oscillations. This role of DHEA/DHEA-S assumes critical significance in assisted reproductive technology and in-vitro fertilization treatment cycles where physical, chemical, and mechanical methods are employed for artificial oocyte activation to enhance fertilization rates. However, since these methods are invasive and may also cause adverse epigenetic modifications; oral or culture-media supplementation with DHEA/DHEA-S provides a noninvasive innate mechanism of in-vitro oocyte activation based on physiological metabolic pathway.

Does the use of calcium ionophore during artificial oocyte activation demonstrate an effect on pregnancy rate? A meta-analysis

OBJECTIVE

To study the effect, if any, of calcium ionophore as a method of artificial oocyte activation (AOA) on pregnancy outcomes and fertilization rates.

DESIGN

Meta-analysis of randomized controlled trials, prospective observational and retrospective trials, case reports, and a case-control trial.

SETTING

University-affiliated teaching hospital.

PATIENT(S)

Infertile couples undergoing fertilization treatment.

INTERVENTION(S)

Use of calcium ionophore during AOA.

MAIN OUTCOME MEASURE(S)

Odds ratio (OR) as the summary statistic for binary variables was used. Both a fixed and random effects model were applied. Subgroup analysis using quantitative methodology (risk of bias, metaregression) and graphical comparison (funnel plot) assessed statistical heterogeneity.

RESULT(S)

Fourteen studies were selected. AOA with calcium ionophore increased the overall clinical pregnancy rate (per ET; OR = 3.48; 95% confidence interval [CI], 1.65-7.37) and the live birth rate (OR = 3.33; 95% CI, 1.50-7.39). This effect of adding calcium ionophore was further demonstrated with fertilization, cleavage, blastocyst, and implantation rates. Subgroup analysis further supported our findings (studies where n > 10 in both arms; random and fixed effects models). A metaregression (beta = -.145) found that as the quality of the study increases, the effect of calcium ionophore is significantly more pronounced with regards to overall pregnancy rate.

CONCLUSION(S)

AOA with calcium ionophore treatment after intracytoplasmic sperm injection (ICSI) results in a statistically significant improvement in fertilization, cleavage, blastulation, and implantation rates, as well as overall pregnancy and live-birth rates. The conclusion of this systematic review, demonstrating a strong effect of calcium ionophore use, is reassuring and promising, particularly for couples for whom ICSI alone yields poor fertilization rates.

Strategies to improve fertilisation rates with assisted conception: a systematic review

Successful fertilisation is one of the key steps determining success of assisted conception. Various factors including sperm or oocyte pathology and environmental factors have a significant impact on fertilisation rates. This systematic review is aimed to evaluate the existing evidence about factors affecting fertilisation and strategies to improve fertilisation rates. A literature search was performed using Ovid MEDLINE ® (Jan 1950-April 2016), EMBASE (Jan 1950-April 2016), Ovid OLDMEDLINE ®, Pre-MEDLINE (Jan 1950-April 2016) and the Cochrane Library. Relevant key words were used to combine sets of results and a total 243 papers were screened. Only qualitative analysis was performed, as there was major heterogeneity in study design and methodology for quantitative synthesis. Factors affecting fertilisation were divided into sperm- and oocyte-related factors. The methods to improve fertilisation rates were grouped together based on the approach used to improve fertilisation rates. Optimising laboratory condition and procedural effects in techniques is associated with improved fertilisation rates. Various techniques are described to improve fertilisation rates including assisted oocyte activation, physiological intracytoplasmic sperm injection (PICSI) and intracytoplasmic morphologically selected sperm injection (IMSI). This review highlights the promising strategies under research to enhance fertilisation rates. Adequately powered multicentre randomised trials are required to evaluate these techniques before considering clinical application.

"This is where it all started" - the pivotal role of PLCζ within the sophisticated process of mammalian reproduction: a systemic review

Mammalian reproduction is one of the most complex and fascinating biological phenomenon, which aims to transfer maternal and paternal genetic material to the next generation. At the end of oogenesis and spermatogenesis, both haploid gametes contain a single set of chromosomes ready to form the zygote, the first cell of the newly developing individual. The mature oocyte and spermatozoa remain in a quiescent state, during which the oocyte is characterized by nuclear and cytoplasmic arrest, while the spermatozoa necessitates further maturation within the epididymis and female reproductive track prior to egg fertilization. Either in vivo or in vitro, the sperm initiates a series of irreversible biochemical and physiological modifications in the oocyte. The earliest detected signal after fertilization is cytosolic Ca²⁺ oscillations, a prerequisite step for embryo development. These oscillations trigger the release of the oocyte from the second meiosis arrest towards embryogenesis, also known as “oocyte activation”. Phospholipase C zeta (PLCζ) is a unique sperm-soluble protein responsible for triggering the InsP₃/Ca²⁺ pathway within the oocyte, leading to Ca²⁺ oscillations and consequently to embryo development. The specific structure of PLCζ (compared to other PLCs) enables its specialized activity via the preserved X and Y catalytic domains, as well as distinct features such as rapid onset, high sensitivity to Ca²⁺ and cession of oscillations upon zygote formation. The emerging discoveries of PLCζ have stimulated studies focusing on the possible clinical applications of this protein in male infertility evaluation and management during IVF/ICSI. Fertilization failure is attributed to lack of oocyte second meiosis resumption, suggesting that ICSI failure may be related to impaired PLCζ activity. Microinjection of recombinant human PLCζ to human oocytes after ICSI fertilization failure may trigger Ca²⁺ oscillations and achieve successful fertilization, offering new hope for couples traditionally referred to sperm donation. However, more studies are still required prior to the routine implementation of this approach in the clinic. Directions for future studies are discussed.

The combination of calcium ionophore A23187 and GM-CSF can safely salvage aged human unfertilized oocytes after ICSI

PURPOSE

Artificial oocyte activation using calcium ionophores and enhancement of embryonic developmental potential by the granulocyte-macrophage colony-stimulating factor (GM-CSF) have already been reported. In this study, we evaluated the synergistic effect of these two methods on aged human unfertilized oocytes after intracytoplasmic sperm injection (ICSI). Then, we cultured the resulting embryos to the blastocyst stage and screened them for chromosomal abnormalities, to assess the safety of this protocol.

METHODS

Aged human oocytes deemed unfertilized after ICSI were activated, either by briefly applying the calcium ionophore A23187 alone (group A) or by briefly applying the ionophore and then supplementing the culture medium with recombinant human GM-CSF (rhGM-CSF) (group B). Next, the development was monitored in a time-lapse incubator system, and ploidy was analyzed by array comparative genomic hybridization (aCGH), after whole embryo biopsy and whole genome amplification. Differences between oocytes and resulting embryos in both groups were evaluated statistically.

RESULTS

Oocytes unfertilized after ICSI can be activated with the calcium ionophore A23187 to show two pronuclei and two polar bodies. Addition of rhGM-CSF in the culture medium of A23187-activated oocytes enhances their cleaving and blastulation potential and results in more euploid blastocysts compared to the culture medium alone.

CONCLUSIONS

This study shows that activating post-ICSI aged human unfertilized oocytes with a combination of a calcium ionophore and a cytokine can produce good-morphology euploid blastocysts.

Relationship between Potential Sperm Factors Involved in Oocyte Activation and Sperm DNA Fragmentation with Intra-Cytoplasmic Sperm Injection Clinical Outcomes

Objective

The present study aimed to simultaneously evaluate the association between expression of three potential factors [post-acrosomal sheath WW domain-binding protein (PAWP), phospholipase Cζ (PLCζ), and truncated form of the kit receptor (TR-KIT)] as candidates of oocyte activation with fertilization rate and early embryonic development.

Materials and Methods

In this experimental study, semen samples were collected from 35 intra-cytoplasmic sperm injection (ICSI) candidates and analyzed according to World Health Organization criteria (2010). Each sample was divided into two parts. The first part was processed for insemination by density-gradient centrifugation (DGC) and the second part was prepared for assessment of sperm morphology (Papanicolaou staining), DNA fragmentation [transferase dUTP nick end labeling (TUNEL)], and three Sperm-borne oocyte-activating factor (s) (SOAFs)-PLCζ, PAWP, and TR-KIT.

Results

Significant positive correlations existed between the percentages of PLCζ, PAWP, and TR-KIT with fertilization rate. In addition, significant negative correlations existed between the percentage of DNA fragmentation with the percentages of PLCζ and PAWP. We did not find a relationship between percentages of PLCζ, PAWP, and TR-KIT with embryo quality and pregnancy rate (P>0.05). There was a significant negative correlation between percentage of DNA fragmentation with fertilization and embryo quality.

Conclusion

Oocyte activation was associated with the studied sperm factors (PAWP, PLCζ, and TR-KIT). These factors might hold the potential to be considered as diagnostic factors in the assessment of semen samples to evaluate their potential to induce oocyte activation. In addition, we observed a significant association between DNA fragmentation with fertilization, as well as embryo quality and expression of PAWP and PLCζ, which indicated that men with high degrees of DNA fragmentation might require artificial oocyte activation. Whether such action should take place, and its cost and benefits should be evaluated in the future.

Gamete activation: basic knowledge and clinical applications

Background

The first clues to the process of gamete activation date back to nearly 60 years ago. The mutual activation of gametes is a crucial event during fertilization. In the testis and ovaries, spermatozoa and oocytes are in a state of meiotic and metabolic quiescence and require reciprocal signals in order to undergo functional changes that lead to competence for fertilization. First, the oocyte activates sperm by triggering motility, chemoattraction, binding and the acrosome reaction, culminating with the fusion of the two plasma membranes. At the end of this cascade of events, collectively known as sperm capacitation, sperm-induced oocyte activation occurs, generating electrical, morphological and metabolic modifications in the oocyte.

Objective and rationale

The aim of this review is to provide the current state of knowledge regarding the entire process of gamete activation in selected specific animal models that have contributed to our understanding of fertilization in mammals, including humans. Here we describe in detail the reciprocal induction of the two activation processes, the molecules involved and the mechanisms of cell interaction and signal transduction that ultimately result in successful embryo development and creation of a new individual.

Search methods

We carried out a literature survey with no restrictions on publication date (from the early 1950s to March 2016) using PubMed/Medline, Google Scholar and Web of Knowledge by utilizing common keywords applied in the field of fertilization and embryo development. We also screened the complete list of references published in the most recent research articles and relevant reviews published in English (both animal and human studies) on the topics investigated.

Outcomes

Literature on the principal animal models demonstrates that gamete activation is a pre-requisite for successful fertilization, and is a process common to all species studied to date. We provide a detailed description of the dramatic changes in gamete morphology and behavior, the regulatory molecules triggering gamete activation and the intracellular ions and second messengers involved in active metabolic pathways in different species. Recent scientific advances suggest that artificial gamete activation may represent a novel technique to improve human IVF outcomes, but this approach requires caution.

Wider implications

Although controversial, manipulation of gamete activation represents a promising tool for ameliorating the fertilization rate in assisted reproductive technologies. A better knowledge of mechanisms that transform the quiescent oocyte into a pluripotent cell may also provide new insights for the clinical use of stem cells.

Clinical efficiency of Piezo-ICSI using micropipettes with a wall thickness of 0.625 μm

PURPOSE

The purposes of the present study are to assess the clinical efficiency of Piezo-intracytoplasmic sperm injection (ICSI) and to improve the Piezo-ICSI method for human oocytes.

METHODS

We examined three ICSI methods to determine their clinical efficiency by comparing the survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates. The three ICSI methods tested were conventional ICSI (CI) (using beveled spiked micropipettes with a wall thickness of 1 μm), conventional Piezo-ICSI (CPI) (using flat-tipped micropipettes with a wall thickness of 0.925 μm), and improved Piezo-ICSI (IPI) (using flat-tipped micropipettes with a wall thickness of 0.625 μm). We collectively investigated 2020 mature oocytes retrieved from 437 patients between October 2010 and January 2014.

RESULTS

The survival rates after CI, CPI, and IPI were 90, 95, and 99 %, respectively. The fertilization rates after CI, CPI, and IPI were 68, 75, and 89 %, respectively. The good-quality day-3 embryo rates after CI, CPI, and IPI were 37, 43, and 55 %, respectively. The pregnancy rates after the transfer of good-quality day-3 embryo of CI, CPI, and IPI were 19, 21, and 31 %, respectively. The live birth rates of CI, CPI, and IPI were 15, 16, and 25 %, respectively. Significantly higher survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates were obtained using IPI.

CONCLUSIONS

When comparing the IPI to the CI and CPI, the results revealed that the Piezo-ICSI using flat-tipped micropipettes with a wall thickness of 0.625 μm significantly improves survival, fertilization, good-quality day-3 embryo, pregnancy, and live birth rates.

Case reports to suggest an algorithm for management of total fertilisation failure prior to use of donor gametes

PURPOSE

Total fertilisation failure (TFF), even with intracytoplasmic sperm injection (ICSI), occurs in approximately 3 % of cycles, can be recurrent and the exact cause is difficult to elucidate. Differentiation between oocyte and sperm-related cause of TFF is possible using mouse oocyte-activation techniques, but is not an option within most clinical settings. Therefore, the management of these couples is clinically driven, and the endpoint, if recurrent, is often the use of donor gametes. However, with the invariable lack of a definitive cause of TFF, any decision between the use of donor sperm or oocytes remains an emotive one. We present two case reports demonstrating the importance of appropriate investigation, activation techniques (mechanical and chemical) and clinical management options to develop a clinical algorithm prior to the use of donor gametes.

METHODS

This study is composed of two case reports of assisted reproduction investigation and treatment within an assisted conception unit for couples with recurrent total fertilisation failure.

RESULTS

Using appropriate investigation (endocrine, urological and embryological) and treatments (ICSI, IMSI, oocyte-activation techniques), a fertilisation rate of 48 % was achieved in two cycles in couples following a total of nine previous cycles (and 200 previously collected eggs) with TFF.

CONCLUSIONS

Oocyte activation requires the triggering of intracellular calcium oscillations by the release of a sperm-specific factor (phospholipase C zeta (PLCζ)) into the oocyte cytoplasm. Although, PLCζ deficiencies have been demonstrated as putative causes of failed activation, impaired oocyte responsiveness may also be a factor. The use of donor gametes is often recommended and is often the required endpoint of treatment. However, these reports outline a clinical algorithm that potentially offers success without donation, and also offers a systematic approach to help decide whether donor oocytes or sperm should be recommended.

A preliminary report of successful cleavage after calcium ionophore activation at ICSI in cases with previous arrest at the pronuclear stage

Artificial oocyte activation (AOA) has been previously suggested as a means to overcome the problem of total fertilization failure, which affects about 1-3% of the intracytoplasmic sperm injection (ICSI) cycles. A preliminary study on the application of chemical AOA was conducted using A23187 Ca(2+) ionophore to improve embryonic development in four women with a history of complete fertilization arrest and inability to transit to cleavage stage during previous ICSI trials. Data indicated that activated oocytes resulted in better fertilization, embryonic development and clinical pregnancy in one of the four couples. Therefore, ICSI combined with AOA using Ca(2+) ionophore may be useful in selected patients with cleavage failure, and may help the zygotes to reach more advanced developmental stages.

Treatment with Ca2+ ionophore improves embryo development and outcome in cases with previous developmental problems: a prospective multicenter study

STUDY QUESTION

Does calcium ionophore treatment (A23187, calcimycin) improve embryo development and outcome in patients with a history of developmental problems/arrest?

SUMMARY ANSWER

Application of A23187 leads to increased rates of cleavage to 2-cell stage, blastocyst formation and clinical pregnancy/live birth.

WHAT IS KNOWN ALREADY

Studies on lower animals indicate that changes in intracellular free calcium trigger and regulate the events of cell division. In humans, calcium fluctuations were detected with a peak shortly before cell division. Interestingly, these calcium oscillations disappeared in arrested embryos. Mitotic division blocked with a Ca(2+) chelator could be restored by means of ionophores in an animal model.

STUDY DESIGN, SIZE, DURATION

This prospective, multicenter (five Austrian centers), uncontrolled intervention study (duration 1 year) includes 57 patients who provided informed consent.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Inclusion criteria were complete embryo developmental arrest in a previous cycle (no transfer), complete developmental delay (no morula/blastocyst on Day 5), or reduced blastocyst formation on Day 5 (≤15%). Severe male factor patients and patients with <30% fertilization rate after ICSI were excluded because these would be routine indications for ionophore usage. The total of the 57 immediately preceding cycles in the same patients constituted the control cycles/control group. In the treatment cycles, all metaphase II-oocytes were exposed to a commercially available ready-to-use ionophore for 15 min immediately after ICSI. After a three-step washing procedure, in vitro culture was performed as in the control cycles, up to blastocyst stage when achievable.

MAIN RESULTS AND THE ROLE OF CHANCE

Fertilization rate did not differ (75.4 versus 73.2%); however, further cleavage to 2-cell stage was significantly higher (P < 0.001) in the ionophore group (98.5%) when compared with the control cycles (91.9%). In addition, significantly more (P < 0.05) blastocysts formed on Day 5 in the study compared with the control group (47.6 versus 5.5%, respectively) and this was associated with a significant increase (P < 0.01) in the rates of implantation (44.4 versus 12.5%), clinical pregnancy (45.1 versus 12.8%) and live birth (45.1 versus 12.8%). All babies born at the time of writing (22/28) were healthy.

LIMITATIONS, REASONS FOR CAUTION

The frequency of patients showing embryo developmental problems was expected to be low; therefore, a multicenter approach was chosen in order to increase sample size. In one-third of the cycles, the clinician or patient requested a change of stimulation protocol; however, this did not influence the developmental rate of embryos.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first evidence that developmental incompetence of embryos is an additional indication for ionophore treatment. The present approach is exclusively for overcoming cleavage arrest.

STUDY FUNDING/COMPETING INTERESTS

No funding received. T.E. reports fees from Gynemed, outside the submitted work. All co-authors have no interest to declare.

[Fertilization failure in IVF and ICSI]

OBJECTIVES

To assess male and female clinical and biological parameters that may explain fertilization failure in vitro fertilization (IVF) and IVF with intra-cytoplasmic sperm injection (ICSI).

MATERIAL AND METHODS

Retrospective case-control study including 1282 IVF or ICSI cycles at the centre hospitalier universitaire of Nantes from September 2010 to February 2012. The "Fertilization Failure" group, showing no sign of fertilization, has been compared with the "Control patients" group, getting at least one embryo.

RESULTS

Several significant differences were noted as, in the "Fertilization Failure" group, lower values of antral follicles (P<0.05), of inseminated oocytes (P<0.001) and active sperm (P<0.001) in IVF, and a lower quantity and quality of oocytes (P<0.001) in ICSI. The correlation tests have confirmed a significant association with these parameters. However, the logistic regression tests did not identify explanatory or predictive factor in IVF or ICSI.

CONCLUSION

In our study, in accordance with literature data, impaired sperm parameters were mainly involved in complete fertilization failure in IVF, and a lower oocyte quality in ICSI.

Total fertilization failure in intra-cytoplasmic sperm injection cycles--classification and management

In this retrospective cohort study we intended to propose a classification and preliminary management strategy for couples exhibiting total fertilization failure (TFF) in intra-cytoplasmic sperm injection (ICSI) cycles. Sixteen couples with a total of 27 cycles exhibiting TFF, age <40 and/or more than four M2 oocytes aspirated were enrolled. While TFF occurred in 4.3% of all 3723 ICSI cycles, in women younger than 40 with at least 5 M2 oocytes the TFF rate was 0.7%. Indications for ICSI were severe male factor and unexplained infertility. Of the 16 couples with TFF, 4 demonstrated a single episode of TFF, with either subsequent or former normal fertilizations, thus implying possible sporadic faulty laboratory conditions. Ten couples demonstrated repeated total or very low fertilization rates, hinting at a gamete defect not overcome by ICSI. Two couples experienced TFF in the first and only cycle performed at our unit. We conclude that initial and repeated TFF hints at severe gamete defects for which only donor gametes may prove successful while sporadic TFF events could simply imply a technical modifiable condition.

Assisted oocyte activation following ICSI fertilization failure

The capacity of intracytoplasmic sperm injection (ICSI) to permit almost any type of spermatozoa to fertilize oocytes has made it the most successful treatment for male factor infertility. Despite its high success rates, fertilization failure following ICSI still occurs in 1-3% of couples. Assisted oocyte activation (AOA) is being increasingly applied in human assisted reproduction to restore fertilization and pregnancy rates in couples with a history of ICSI fertilization failure. However, controversy still exists mainly because the artificial activating agents do not mimic precisely the initial physiological processes of mammalian oocyte activation, which has led to safety concerns. This review addresses the mechanism of human oocyte activation and the relatively rare phenomenon of fertilization failure after ICSI. Next, it describes the current diagnostic approaches and focuses on the application, efficiency and safety of AOA in human assisted reproduction.

Analysis of clinical outcomes with respect to spermatozoan origin after artificial oocyte activation with a calcium ionophore

PURPOSE

Fertilization failures have occurred repeatedly in reproductive centers after intracytoplasmic sperm injection (ICSI) and artificial oocyte activation (AOA) has been used to prevent it. This study was performed to investigate whether spermatozoan origin influences clinical outcomes of AOA with a calcium ionophore.

METHODS

A total of 185 ICSI cycles with a history of no or low fertilization was included in this retrospective study. The outcomes of AOA after ICSI were compared with ejaculated-normal, ejaculated-oligo-astheno-terato or extracted-testicular spermatozoa.

RESULTS

There were significant differences between the previous standard ICSI cycles and AOA cycles in the rate of fertilization and clinical outcomes among cases with different sperm origins. Thirty-eight healthy babies (20 singles and 18 twins, 29 cycles) were successfully delivered, and no congenital birth defects were observed.

CONCLUSIONS

Most patients with a no or low fertilization history obtained an increased fertilization rate and a positive clinical outcome with AOA regardless of the origin of spermatozoa.

Efficiency of laser-assisted intracytoplasmic sperm injection in a human assisted reproductive techniques program

OBJECTIVE

Laser-assisted intracytoplasmic sperm injection (LA-ICSI), also known as micro-opening or thinning of the zona pellucida (ZP) prior to ICSI, may help to reduce mechanical damage to the oocyte during the procedure. The aim of the present study was to evaluate and analyze the efficacy of our institutional LA-ICSI program, which features laser-assisted ZP thinning prior to ICSI, in comparison with conventional ICSI (C-ICSI), performed on patients with different clinical characteristics.

METHODS

Patients undergoing a total of 212 ICSI cycles were randomly divided into an LA-ICSI group (106 cycles) and a conventional ICSI group (106 cycles). To reduce tissue damage, we thinned the ZP by approximately 70%, using a laser, before ICSI. Patients thus treated formed the LA-ICSI group. Comparisons included the morphological quality of transferred embryos, blastocyst development of the remaining embryos, and clinical pregnancy, in terms of ICSI method and patient characteristics.

RESULTS

Fertilization, development of remaining embryos, and pregnancy rate were significantly higher in the LA-ICSI group compared with the C-ICSI group. Fertilization, embryonic development, and the pregnancy rate were all improved in younger patients (<38 years of age) and in those who underwent a low number of IVF-ET attempts (<3 trials). In addition, the pregnancy rate was increased in older patients.

CONCLUSION

LA-ICSI may be useful in improving the chance of pregnancy in all ICSI patients.

Oocyte activation, phospholipase C zeta and human infertility

BACKGROUND

Mammalian oocytes are activated by intracellular calcium (Ca(2+)) oscillations following gamete fusion. Recent evidence implicates a sperm-specific phospholipase C zeta, PLCζ, which is introduced into the oocyte following membrane fusion, as the responsible factor. This review summarizes the current understanding of human oocyte activation failure and describes recent discoveries linking certain cases of male infertility with defects in PLCζ expression and activity. How these latest findings may influence future diagnosis and treatment options are also discussed.

METHODS

Systematic literature searches were performed using PubMed, ISI-Web of Knowledge and The Cochrane Library. We also scrutinized material from the United Nations and World Health Organization databases (UNWHO) and the Human Fertilization and Embryology Authority (HFEA).

RESULTS AND CONCLUSIONS

Although ICSI results in average fertilization rates of 70%, complete or virtually complete fertilization failure still occurs in 1-5% of ICSI cycles. While oocyte activation failure can, in some cases, be overcome by artificial oocyte activators such as calcium ionophores, a more physiological oocyte activation agent might release Ca(2+) within the oocyte in a more efficient and controlled manner. As PLCζ is now widely considered to be the physiological agent responsible for activating mammalian oocytes, it represents both a novel diagnostic biomarker of oocyte activation capability and a possible mode of treatment for certain types of male infertility.

Double activation improves rabbit freeze–thawed oocytes developmental potential

Objective: To investigate the effects of various activation methods on freeze–thawed rabbit oocytes developmental potential. Methods: Rabbit oocytes were vitrified by cryoleafs and cryoprotected with ethylene glycol and propanediol. After thawing, the oocytes were fertilized by intracytoplasmic sperm injection (ICSI). Surviving oocytes after ICSI were divided into five groups at random. Group 1: Oocytes (n = 30) activated 1 h after ICSI by calcium ionomycin (I0634); Group 2: Oocytes (n = 26) activated by strontium chloride an hour after ICSI; Group 3: Oocytes (n = 33) activated by I0634 twice; Group 4: Oocytes (n = 28) were activated by strontium chloride twice; Control Group: Inactivated oocytes (n = 39). Blastocysts derived from each group were transplanted to recipient rabbits. Results: Rates of fertilization, cleavage and blastocyst formation of Group 3 were higher than those of Group 1 and Group 2 (81.8% vs 33.3% vs 53.8%, 54.5% vs 16.7% vs 26.9%, p < 0.05; 15.2% vs 3.3% vs 7.7%, p > 0.05). The rabbit transplanted with embryos derived from Group 3 became pregnant. Embryos derived from double activation could implant into endometrium. Conclusion: Double activation may increase freeze–thawed oocytes developmental potential. After activation, oocytes cleavage velocity may be faster than that of oocytes without activation.

Artificial oocyte activation and intracytoplasmic sperm injection

OBJECTIVE

To review different methods for artificial oocyte activation and its impact on intracytoplasmic sperm injection (ICSI).

DESIGN

Literature review.

SETTING

University-based and university-affiliated medical centers.

PATIENT(S)

None.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

None.

RESULT(S)

The ICSI procedure improves fertilization rates in cases of male factor infertility; however, fertilization failure still occurs in 2% to 3% of ICSI cycles. The main cause of failed fertilization is failure to complete oocyte activation. The investigators do not use a variety of mechanical, electrical, and chemical methods to mimic the calcium rise necessary to activate oocytes after ICSI. Chemical activation is the most commonly used method for artificial oocyte activation, resulting in high fertilization rates.

CONCLUSION(S)

Artificial oocyte activation (AOA) may be useful in selected patients who have low fertilization potential. Further studies are required to establish the biosafety of AOA, and clinical tests are needed to evaluate the activation potential of semen samples for proper patient selection.