Three-day-old human unfertilized oocytes after in vitro fertilization/intracytoplasmic sperm injection can be activated by calcium ionophore a23187 or strontium chloride and develop to blastocysts

Oocyte activation for women following intracytoplasmic sperm injection (ICSI)

BACKGROUND

Intracytoplasmic sperm injection (ICSI), a type of assisted reproductive technology (ART), is offered as a treatment option for male factor infertility. Over the years, the indications for ICSI have been expanded, despite uncertainty about its benefits and harms compared to the conventional method of achieving fertilisation. Artificial oocyte activation (AOA), which can be performed by chemical, electrical or mechanical intervention, has been employed during ART ICSI treatment where there has been a history of low fertilization rate or total fertilization failure, and it has been reported to improve reproductive outcomes. It is important to evaluate the clinical effectiveness and safety of AOA in women undergoing ART ICSI treatment.

OBJECTIVES

To evaluate the benefits and harms of artificial oocyte activation in women affected by infertility undergoing intracytoplasmic sperm injection treatment.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, ClinicalTrials.gov and WHO international Clinical Trials Registry Platform (8 August 2024). We also searched reference lists of relevant articles and contacted experts in the field.

SELECTION CRITERIA

Randomized controlled trials comparing artificial oocyte activation (AOA) (chemical, electrical or mechanical interventions) versus no intervention, placebo or another method of AOA in women undergoing ART.

DATA COLLECTION AND ANALYSIS

We used methodological procedures as per Cochrane recommendations. We assessed the risk of bias in the included studies using ROB 2. The primary outcomes were live birth and miscarriage rates. We analyzed data using the risk ratio (RR) and a fixed-effect model. We assessed the certainty of the evidence by using GRADE criteria. We restricted the primary analyses to studies at low risk of bias.

MAIN RESULTS

We included a total of 20 studies, four of which were participant-based randomized trials with 743 participants. The remaining 16 were sibling-oocyte-model randomized studies. We based the main clinical findings of the current review on the participant-based RCTs, and we restricted our primary analysis to studies with a low risk of bias. Based on the one trial with 343 participants that we included in our primary analysis, the evidence is very uncertain about the effect of AOA on the live birth rate when compared to conventional ICSI without AOA in women undergoing ART ICSI (RR 1.97, 95% CI 1.29 to 3.01; one trial; 343 participants). For a typical clinic with a live birth rate of 18% following ART, the addition of AOA may result in live birth rates between 24% and 55%, but this evidence is very uncertain. The evidence is very uncertain about the effect of AOA on the miscarriage rate compared to conventional ICSI without AOA in women undergoing ART ICSI (RR 0.99, 95% CI 0.48 to 2.04; one trial; 343 participants). If the miscarriage rate was 9% following ART, addition of oocyte activation may result in miscarriage rates between 4% and 18%, but this evidence is very uncertain. The evidence is very uncertain about the effect of AOA on the clinical pregnancy rate compared to conventional ICSI without AOA in women undergoing ART ICSI (RR 1.67, 95% CI 1.20 to 2.32; one trial; 343 participants). The evidence is very uncertain about the effect of AOA on the multiple pregnancy rate per participant compared to conventional ICSI without AOA in women undergoing ART ICSI (RR 1.91, 95% CI 0.48 to 7.67; one trial; 343 participants). The evidence is very uncertain about the effect of AOA on the total fertilization failure rate compared to conventional ICSI without AOA in women undergoing ART ICSI (RR 0.05, 95% CI 0.01 to 0.40; one trial; 343 participants). When we stratified our analysis according to various infertility factors, we found low-certainty evidence that in couples undergoing ICSI treatment who have had a history of low or no fertilization, AOA may help improve the live birth rate while making little or no difference to the miscarriage rate. Further research is needed to confirm or refute this finding. None of the trials reported congenital anomalies (birth defects) as an outcome. Lack of short- or long-term safety data is an important limitation of the review and of the trials in this field. We did not find any trials that compared two different methods of oocyte activation.

AUTHORS' CONCLUSIONS

We are uncertain about the effect of AOA on the live birth and miscarriage rates in women undergoing ART ICSI. In the subpopulation of those who have had a previous history of low or no fertilization, AOA may result in an increase in the live birth rate when compared to conventional ICSI without AOA, while making little or no difference to the miscarriage rate. There was considerable variation in the protocols used for chemical AOA, which affects the generalizability of the findings. Due to the very low to low certainty of evidence, the results should be interpreted with caution.

Using Machine Learning to Construct the Blood-Follicle Distribution Models of Various Trace Elements and Explore the Transport-Related Pathways with Multiomics Data

Permeabilities of various trace elements (TEs) through the blood-follicle barrier (BFB) play an important role in oocyte development. However, it has not been comprehensively described as well as its involved biological pathways. Our study aimed to construct a blood-follicle distribution model of the concerned TEs and explore their related biological pathways. We finally included a total of 168 women from a cohort of in vitro fertilization-embryo transfer conducted in two reproductive centers in Beijing City and Shandong Province, China. The concentrations of 35 TEs in both serum and follicular fluid (FF) samples from the 168 women were measured, as well as the multiomics features of the metabolome, lipidome, and proteome in both plasma and FF samples. Multiomics features associated with the transfer efficiencies of TEs through the BFB were selected by using an elastic net model and further utilized for pathway analysis. Various machine learning (ML) models were built to predict the concentrations of TEs in FF. Overall, there are 21 TEs that exhibited three types of consistent BFB distribution characteristics between Beijing and Shandong centers. Among them, the concentrations of arsenic, manganese, nickel, tin, and bismuth in FF were higher than those in the serum with transfer efficiencies of 1.19-4.38, while a reverse trend was observed for the 15 TEs with transfer efficiencies of 0.076-0.905, e.g., mercury, germanium, selenium, antimony, and titanium. Lastly, cadmium was evenly distributed in the two compartments with transfer efficiencies of 0.998-1.056. Multiomics analysis showed that the enrichment of TEs was associated with the synthesis and action of steroid hormones and the glucose metabolism. Random forest model can provide the most accurate predictions of the concentrations of TEs in FF among the concerned ML models. In conclusion, the selective permeability through the BFB for various TEs may be significantly regulated by the steroid hormones and the glucose metabolism. Also, the concentrations of some TEs in FF can be well predicted by their serum levels with a random forest model.

Successful Live Birth Outcome Following Assisted Activation of Failed Fertilized Oocytes

Here, we report on a rare case of a live birth following assisted oocyte activation of failed fertilized oocytes. A 34-year-old nulliparous woman presenting at a university-based assisted reproductive technology center with multi-factor infertility underwent an IVF cycle using intracytoplasmic sperm injection (ICSI) of frozen/thawed testicular sperm aspiration (TESA) sample and preimplantation genetic testing for aneuploidy (PGT-A). All oocytes displayed failed fertilization at assessment 18 h post-ICSI. Rescue of this cycle was achieved with the use of an assisted oocyte activation (AOA) protocol, whereby oocytes were subjected to AOA with calcium ionophore at 19 h post-ICSI and assessed for blastocyst development. Blastocyst-stage embryos were biopsied for PGT-A analysis with one of the three embryos reporting as genetically normal. This embryo was transferred in a frozen embryo transfer cycle and resulted in a normal pregnancy and term live birth. In conclusion, application of AOA protocols following failed fertilization outcomes can lead to viable, genetically normal embryos capable of resulting in a live birth.

The influence of high-order chromatin state in the regulation of stem cell fate

In eukaryotic cells, genomic DNA is hierarchically compacted by histones into chromatin, which is initially assembled by the nucleosome and further folded into orderly and flexible structures that include chromatin fiber, chromatin looping, topologically associated domains (TADs), chromosome compartments, and chromosome territories. These distinct structures and motifs build the three-dimensional (3D) genome architecture, which precisely controls spatial and temporal gene expression in the nucleus. Given that each type of cell is characterized by its own unique gene expression profile, the state of high-order chromatin plays an essential role in the cell fate decision. Accumulating evidence suggests that the plasticity of high-order chromatin is closely associated with stem cell fate. In this review, we summarize the biological roles of the state of high-order chromatin in embryogenesis, stem cell differentiation, the maintenance of stem cell identity, and somatic cell reprogramming. In addition, we highlight the roles of epigenetic factors and pioneer transcription factors (TFs) involved in regulating the state of high-order chromatin during the determination of stem cell fate and discuss how H3K9me3-heterochromatin restricts stem cell fate. In summary, we review the most recent progress in research on the regulatory functions of high-order chromatin dynamics in the determination and maintenance of stem cell fate.

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.

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

PURPOSE

When rescue artificial oocyte activation (ROA) is performed on the day after intracytoplasmic sperm injection (ICSI) or later, embryonic development is poor and seldom results in live births. The efficacy of an early ROA after ICSI is unclear. Is early ROA effective in rescuing unfertilized oocytes that have not undergone second polar body extrusion several hours after ICSI?

METHODS

We performed retrospective cohort study between October 2016 and September 2019, targeting 2891 oocytes in 843 cycles when ICSI was performed. We performed ROA with calcium ionophore on 395 of the 475 oocytes with no second polar extrusion 2.5-6 h after ICSI.

RESULTS

The normal fertilization rate of ROA oocytes was significantly higher than non-ROA oocytes (65.8% vs 6.7%, P < 0.001). The blastocyst development rate in ROA oocytes was significantly lower than spontaneously activated oocytes (48.9% vs 67.2%, P < 0.001). The ROA oocyte implantation rate did not significantly differ from the spontaneously activated oocytes (36.0% vs 41.2%). We observed no differences in the implantation rates and blastocyst development rates over the 2.5-6 h from ICSI until ROA.

CONCLUSION

Early ROA is effective, and the optimal timing appears to be 2.5-6 h after ICSI.

Kinetics of meiotic maturation in oocytes from unstimulated ovaries and duration of pronucleus presence and preimplantation development

OBJECTIVE

To evaluate the meaning of meiotic maturation kinetics and duration of pronucleus presence (DPP) for parthenogenetic activation outcome.

DESIGN

Retrospective study.

SETTING

University hospital.

PATIENT(S)

Eight patients with endometrioid adenocarcinoma and 65 patients who underwent in vitro fertilization (IVF) with intracytoplasmic sperm injection (ICSI).

INTERVENTION(S)

After collection of oocytes from nonstimulated ovaries of patients with endometrioid adenocarcinoma, in vitro maturation (IVM) and parthenogenetic activation performed with time-lapse imaging; after ICSI, embryos similarly incubated with time-lapse imaging.

MAIN OUTCOME MEASURE(S)

Timing of the release of the first polar body (fPB), DPP, and developmental stage with IVM and parthenogenetic activation; after ICSI, assessment of DPP and preimplantation developmental stage.

RESULT(S)

With IVM, 55.2% of oocytes matured; 53.1% of fPBs were released within 24 hours, and 46.9% of fPBs were released after 24 hours. Regarding developmental stage, oocytes that released fPB later during IVM tended to develop more than oocytes that released the fPB within 24 hours. For embryos from parthenogenetic activation the DPP was statistically significantly shorter than the DPP of embryos from ICSI. With ICSI, the DPP was statistically significantly shorter in embryos that developed to ≥8 cells than embryos whose final development included ≤7 cells. The development rate in parthenogenetic activation was statistically significantly lower than that in ICSI.

CONCLUSION(S)

Embryo development is negatively affected by DPP that is too short or too long. When the DPP was short with parthenogenetic activation, embryo development did not proceed, indicating that DPP is an important determinant of parthenogenetic activation outcomes as with the timing of fPB release.

Calcium Oscillatory Patterns and Oocyte Activation During Fertilization: a Possible Mechanism for Total Fertilization Failure (TFF) in Human In Vitro Fertilization?

This paper reviews the effects of calcium oscillatory patterns in oocytes and early embryo development. Total fertilization failure (TFF) is the failure of fertilization in all oocytes in a human IVF cycle, even after treatment with intracytoplasmic sperm injection (ICSI). It is not well understood and currently attributed to oocyte activation deficiency. Calcium signaling is important in oocyte activation events. Calcium oscillations, in particular, have been reported in animal and human oocytes after fertilization. Abnormal calcium oscillations after fertilization may be the principal mechanism for TFF. While studies also establish strong associations between abnormal calcium oscillatory patterns and suboptimal developmental outcomes, critical basic parameters and their mechanism of action have yet to be identified. Empirical use of artificial oocyte activation (AOA) methods has shown initial success in helping patients overcome TFF. The AOA methods attempt to raise calcium levels after fertilization, but the efficacy and safety of these AOA methods are still in early stages of addressing TFF. Additional information about calcium oscillatory patterns and the effects of AOA in human ART may allow the prevention of TFF or allow treatment of TFF patients effectively and safely.

In vitro Activation of Mouse Oocytes through Intracellular Ca2+ Regulation

Background:

Ca²⁺ signaling pathway is suggested to play an essential role in mediating oocyte maturation.

Aims:

The aim of this study was to evaluate intracellular Ca²⁺ of resistant immature oocytes that failed to resume meiosis following subsequent in vitro culture reach metaphase II after calcium ionophore A23187 activation.

Settings and Design:

This in vitro analytical experimental study was conducted at Animal Science Laboratory of Indonesian Medical Education and Research Institute (IMERI), Human Reproductive Infertility and Family Planning of IMERI, and Electrophysiology Imaging of Terpadu Laboratory, Faculty of Medicine, University of Indonesia.

Methods:

A total of 308 oocytes classed as resistant immature following in vitro culture were randomly allocated to control (n = 113) and treatment groups (n = 195). The oocyte activation group was exposed to A23187 solution for 15 min and then washed extensively. Maturation was evaluated by observing the first polar body extrusion 20‒24 h after A23187 exposure. Ca²⁺ imaging was conducted using a confocal laser scanning microscope to identify the dynamic of Ca²⁺ response.

Statistical Analysis:

SPSS 20, Chi-square, and Mann–Whitney U-test were used in this study.

Results:

Activation of resistant immature oocytes with A23187 significantly increased the number of oocyte maturation compared with the control group (P < 0.001). Furthermore, fluorescent intensity measurements exhibited a significant increase in the germinal vesicle stage when activated (P = 0.005), as well as the metaphase I stage, even though differences were not significant (P = 0.146).

Conclusion:

Artificial activation of resistant immature oocyte using chemical A23187/calcimycin was adequate to initiate meiosis progress.

Comparison of Human Oocyte Activation Between Round-Headed Sperm Injection Followed by Calcium Ionophore Treatment and Normal Sperm Injection in a Patient With Globozoospermia

Fertilization failure is common in patients with round-headed sperm, a form of globozoospermia. Artificial oocyte activation is able to assist oocyte fertilization after sperm injection in these patients. Comparisons between oocyte fertilization with or without calcium ionophore have been reported in patients with round-headed sperm. However, no comparison has been reported between round-headed sperm injection followed by calcium ionophone activation and normal sperm injection. In this case report, half of oocytes from a patient were injected with her partner's round-headed sperm followed by calcium ionophore activation, and the other half of oocytes were injected with a donor sperm without calcium ionophore activation. The injected oocytes were cultured to examine fertilization, embryo development, and embryonic aneuploidies in the resulting blastocysts. The fertilization rate was lower in round-headed sperm injected oocytes (3/6) than that in donor sperm injected oocytes (5/6), but rates of blastocyst and aneuploidies were similar in the resulting embryos between the two groups. A euploid blastocyst resulted from round-headed sperm injection was transferred, and a healthy baby was delivered. These results indicate that calcium ionophore treatment can assist oocyte activation in patients with round-headed sperm, but its efficiency to activate oocytes is lower than that induced by a normal sperm injection. However, embryo development and chromosome integrity may not be affected by calcium ionophore treatment.

Effects of calpain inhibitor on the apoptosis of hepatic stellate cells induced by calcium ionophore A23187

We previously showed that changes in calcium concentrations were related to cell apoptosis in vitro. The endoplasmic reticulum (ER) is the main component of calcium storage and signal transduction, and disrupting the balance of intracellular Ca²⁺ can cause endoplasmic reticulum stress (ERS). In this process, the ER releases stored Ca ²⁺ into the cytoplasm and activates calpain-2. To further investigate the effect of calpain in hepatic stellate cells (HSCs), in the current study, we examine the effect of N-acetyl-leu-leu-norleucinal (ALLN) on apoptosis resulting from calcium ionophore A23187-induced ERS. Our findings indicate that calpain inhibition reduces calcium ionophore A23187-induced apoptosis of HSCs and decreases the expression of ER stress proteins that may be related to the calpain/caspase signaling pathway.

Somatic Cell Nuclear Transfer Reprogramming: Mechanisms and Applications

Successful cloning of monkeys, the first non-human primate species, by somatic cell nuclear transfer (SCNT) attracted worldwide attention earlier this year. Remarkably, it has taken more than 20 years since the cloning of Dolly the sheep in 1997 to achieve this feat. This success was largely due to recent understanding of epigenetic barriers that impede SCNT-mediated reprogramming and the establishment of key methods to overcome these barriers, which also allowed efficient derivation of human pluripotent stem cells for cell therapy. Here, we summarize recent advances in SCNT technology and its potential applications for both reproductive and therapeutic cloning.

Effects of calcium Ionophore A23187 on the apoptosis of hepatic stellate cells stimulated by transforming growth factor-β1

Background

Our previous study showed that during in vitro experiments changes in calcium concentration were associated with apoptosis. We presumed that the calcium ion might play a role as intermediate messenger for apoptosis-related genes. No such evidence has been reported in the literature. Here, we investigate the effect of calcium ionophore A23187 on the apoptosis of rat hepatic stellate cells (HSCs) stimulated by transforming growth factor-β₁ (TGF-β₁) to explore the mechanism of apoptosis through the endoplasmic reticulum stress pathway.

Methods

The apoptotic rate was determined using flow cytometry. The changes in Ca²⁺ level in HSCs were examined with laser confocal microscopy. The expressions of caspase-12 GRP78 and caspase-9 were assayed via western blot.

Results

The respective apoptosis rates for the blank group, the TGF-β₁ group and the TGF-β₁ + low, medium and high dose calcium ionophore A23187 groups were 3.40 ± 0.10%, 1.76 ± 0.12%, 5.86 ± 0.31%, 11.20 ± 0.48% and 15.08 ± 0.75%, with significant differences between the groups (p < 0.05). The concentration of Ca²⁺and the expression of the GRP78, caspase-9 and caspase-12 proteins significantly increased with increasing calcium ionophore A23187 doses (p < 0.05).

Conclusion

Calcium ionophore A23187 increased intracellular Ca²⁺ and activated endoplasmic reticulum stress, which promoted HSC apoptosis.

Single Ca2+ transients vs oscillatory Ca2+ signaling for assisted oocyte activation: limitations and benefits

Oocyte activation is a calcium (Ca²⁺)-dependent process that has been investigated in depth, in particular, regarding its impact on assisted reproduction technology (ART). Following a standard model of signal transduction, Ca²⁺ drives the meiotic progression upon fertilization in all species studied to date. However, Ca²⁺ changes during oocyte activation are species specific, and they can be classified in two modalities based on the pattern defined by the Ca²⁺ signature: a single Ca²⁺ transient (e.g. amphibians) or repetitive Ca²⁺ transients called Ca²⁺ oscillations (e.g. mammals). Interestingly, assisted oocyte activation (AOA) methods have highlighted the ability of mammalian oocytes to respond to single Ca²⁺ transients with normal embryonic development. In this regard, there is evidence supporting that cellular events during the process of oocyte activation are initiated by different number of Ca²⁺ oscillations. Moreover, it was proposed that oocyte activation and subsequent embryonic development are dependent on the total summation of the Ca²⁺ peaks, rather than to a specific frequency pattern of Ca²⁺ oscillations. The present review aims to demonstrate the complexity of mammalian oocyte activation by describing the series of Ca²⁺-linked physiological events involved in mediating the egg-to-embryo transition. Furthermore, mechanisms of AOA and the limitations and benefits associated with the application of different activation agents are discussed.

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.

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.

Parthenogenesis and Human Assisted Reproduction

Parthenogenetic activation of human oocytes obtained from infertility treatments has gained new interest in recent years as an alternative approach to create embryos with no reproductive purpose for research in areas such as assisted reproduction technologies itself, somatic cell, and nuclear transfer experiments and for derivation of clinical grade pluripotent embryonic stem cells for regenerative medicine. Different activating methods have been tested on human and nonhuman oocytes, with varying degrees of success in terms of parthenote generation rates, embryo development stem cell derivation rates. Success in achieving a standardized artificial activation methodology for human oocytes and the subsequent potential therapeutic gain obtained from these embryos depends mainly on the availability of gametes donated from infertility treatments. This review will focus on the creation of parthenotes from clinically unusable oocytes for derivation and establishment of human parthenogenetic stem cell lines and their potential applications in regenerative medicine.

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.