Effects of failed oocyte activation and sperm protamine deficiency on fertilization post-ICSI

The developmental competence of human metaphase I oocytes with delayed maturation in vitro

OBJECTIVE

To evaluate whether metaphase I (MI) oocytes completing maturation in vitro to metaphase II ("MI-MII oocytes") have similar developmental competence as the sibling metaphase II (MII) oocytes that reached maturity in vivo.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center.

PATIENT(S)

A total of 1,124 intracytoplasmic sperm injection (ICSI) cycles from 800 patients at a single academic center between April 2016 and December 2020 with at least 1 MII oocyte immediately after retrieval and at least 1 sibling "MI-MII oocyte" that was retrieved as MI and matured to MII in culture before ICSI were included in the study.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

A total of 7,865 MII and 2,369 sibling MI-MII oocytes retrieved from the same individuals were compared for the fertilization and blastocyst formation rates. For patients who underwent single euploid blastocyst transfers (n = 406), the clinical pregnancy, spontaneous pregnancy loss, and live birth rates were compared between the 2 groups.

RESULT(S)

The fertilization rate was significantly higher in MII oocytes than in delayed matured MI-MII oocytes (75.9% vs. 56.1%). Similarly, the blastocyst formation rate was higher in embryos derived from MII oocytes than in those from MI-MII oocytes (53.8% vs. 23.9%). The percentage of euploid embryos derived from MII oocytes was significantly higher than that of those from MI-MII oocytes (49.2% vs. 34.7%). Paired comparison of sibling oocytes within the same cycle showed higher developmental competence of the MII oocytes than that of MI-MII oocytes. However, the pregnancy, spontaneous pregnancy loss, and live birth rates after a single euploid blastocyst transfer showed no statistically significant difference between the 2 groups (MII vs. MI-MII group, 65.7% vs. 74.1%, 6.4% vs. 5.0%, and 61.5% vs. 70.0%, respectively).

CONCLUSION(S)

Compared with oocytes that matured in vivo and were retrieved as MII, the oocytes that were retrieved as MI and matured to MII in vitro before ICSI showed lower developmental competence, including lower fertilization, blastocyst formation, and euploidy rates. However, euploid blastocysts from either cohort resulted in similar live birth rates, indicating that the MI oocytes with delayed maturation can still be useful even though the overall developmental competence was lower than that of their in vivo matured counterparts.

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.

Elevated seminal protein carbonyl concentration is correlated with asthenozoospermia and affects adversely the laboratory intracytoplasmic sperm injection (ICSI) outcomes

Elevated concentrations of reactive oxygen species (ROS) in the semen can lead to oxidative protein damage as they react with the amino acids' side chains in the protein, leading to the generation of carbonyl groups. This study aimed to investigate the effect of protein carbonyl (PC) concentration on sperm motility and the laboratory intracytoplasmic sperm injection (ICSI) outcomes. A total of 150 couples from the ICSI cycle were enrolled in this study and were divided into three groups (G) according to the PC concentration as following, G1 included samples with PC concentrations <0.65 nmol/mg, G2 included samples with 0.65≤PC≤2.23 nmol/mg and G3 included samples with PC>2.23 (nmol/mg). PC concentrations were measured in all semen samples, and the laboratory ICSI outcomes were evaluated for all injected oocytes. The Kruskal-Wallis p-values for the differences in the medians of sperm motility, fertilisation rate, embryo cleavage score and embryo quality score were <0.05. Furthermore, Dunn's post hoc test showed a significant difference between all groups, p-values <0.05, except for the medians of embryo quality score between G2 and G3. In conclusion, our results showed that sperm motility and laboratory ICSI outcomes are affected negatively by higher concentrations of PC in the semen.

Impact of Mitochondrial Genetic Variants in ND1, ND2, ND5, and ND6 Genes on Sperm Motility and Intracytoplasmic Sperm Injection (ICSI) Outcomes

Sperm mitochondrial dysfunction causes the generation of an insufficient amount of energy needed for sperm motility. This will affect sperm fertilization capacity, and thus, most asthenozoospermic men usually require assisted reproductive techniques. The etiology of asthenozoospermia remains largely unknown. The current study aimed to investigate the effect of mitochondrial genetic variants on sperm motility and intracytoplasmic sperm injection (ICSI) outcomes. A total of 150 couples from the ICSI cycle were enrolled in this study. One hundred five of the male partners were asthenozoospermic patients, and they were subdivided into three groups according to their percentage of sperm motility, while forty-five of the male partners were normozoospermic. Genetic variants were screened using direct Sanger's sequencing in four mitochondrial genes (nicotinamide adenine dinucleotide hydrogen (NADH) dehydrogenase 1 (ND1), NADH dehydrogenase 2 (ND2), NADH dehydrogenase 5 (ND5), and NADH dehydrogenase 6 (ND6)). We identified three significant variants: 13708G>A (rs28359178) in ND5, 4216T>C (rs1599988) in ND1, and a novel 12506T>A in ND5 with P values 0.006, 0.036, and 0.013, respectively. The medians of sperm motility, fertilization rate, embryo cleavage score, and embryo quality score were significantly different between men showing 4216T>C, 12506T>A, 13708G>A and wild type, Mann-Whitney P values for the differences in the medians were < 0.05 in all of them. The results from this study suggest that 13708G>A, 12506T>A, and 4216 T>C variants in sperm mitochondrial DNA negatively affect sperm motility and ICSI outcomes.

Altered mitochondrial function in spermatozoa from patients with repetitive fertilization failure after ICSI revealed by proteomics

BACKGROUND

Unexplained fertilization failure (FF), occurring in 1-3% of intracytoplasmic sperm injection (ICSI) cycles, results in both psychological and financial burden for the patients. However, the molecular causes behind FF remain largely unknown. Mass spectrometry is a powerful technique to identify and quantify proteins across samples; however, no study so far has used it to dissect the proteomic signature of spermatozoa with FF after ICSI.

OBJECTIVE

To investigate whether sperm samples from patients suffering repetitive FF after ICSI display alterations in their protein content.

MATERIAL AND METHODS

Seventeen infertile men were included: 5 patients presented FF in ≥3 consecutive ICSI cycles, while 12 patients had a fertilization rate >75% (controls). Individual sperm samples were subjected to 2D-LC-MS/MS. Both conventional and novel statistical approaches were used to identify differentially abundant proteins. Additionally, analysis of mitochondrial and proteasomal abundance and activity were performed, using Western blot, FACS analysis of JC-1 staining and AMC-peptide fluorometric assay.

RESULTS

Four proteins presented lower abundance (FMR1NB, FAM209B, RAB2B, and PSMA1) in the FF group compared to controls, while five mitochondrial proteins presented higher abundance in FF (DLAT, ATP5H, SLC25A3, SLC25A6, and FH) (p < 0.05). The altered abundance of mitochondrial DLAT and proteasomal PSMA1 was corroborated by Western blot. Of relevance, novel stable-protein pair analysis identified 73 correlations comprising 28 proteins within controls, while different mitochondrial proteins (ie, PDHA2, PHB2, and ATP5F1D) lost >50% of these correlations in specific FF samples pointing out specific mitochondrial deregulations.

DISCUSSION

This is the first proteomic analysis of spermatozoa from patients who resulted in fertilization failure after ICSI. The altered proteins, most of them related to mitochondrial function, could help to identify diagnostic/prognostic markers of fertilization failure and could further dissect the molecular paternal contribution to reach successful fertilization.

CONCLUSION

Sperm samples from patients with FF after ICSI present altered abundance of different proteins, including mainly mitochondrial proteins.

Relationship between sperm telomere length and sperm quality in infertile men

Telomeres, noncoding and repetitive DNA sequences play a significant function in chromatin integrity. Telomere length is age-dependent in somatic cells, while it increases in sperm cell with age. Therefore, we aimed to assess sperm chromatin, leucocyte and sperm telomere length (LTL, STL) in spermatozoon of 38 infertile and 19 fertile men aged between 20 and 50 years. Protamine deficiency (chromomycin A3 test), DNA fragmentation (TUNEL assay), lipid peroxidation (Bodipy probe) and telomere length (quantitative real-time PCR) were assessed. A significant decrease in mean of sperm concentration and motility and a significant increase in means of sperm abnormal morphology, DNA fragmentation, lipid peroxidation and protamine deficiency were observed in infertile compared with fertile men. In addition, the mean of LTL and STL were significantly shorter in infertile men compared with fertile individuals. We observed significant associations between telomere length with sperm concentration, DNA fragmentation and lipid peroxidation. We hypothesised that increased oxidative stress in spermatozoa of infertile men can result in abnormal packaging of chromatin, damage of DNA and shorter sperm telomere length. Together, these anomalies may account for fertility failure in these individuals.

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.

PROTAMINE1 and PROTAMINE2 genes expression in the sperms of oligoasthenospermic individuals and intrauterine insemination candidates couples: Is there any significant differences?

Background:

Male infertility refers to a male's inability to cause pregnancy in a fertile female. It seems the large portion of this category of infertility, has roots in genetic factors. PROTAMINE family is one of the most important genes which are involved in male factor infertility. Hence, the aim of this study is to evaluate PROTAMINE1 and PROTAMINE2 (P1 and P2) genes expression in oligoasthenospermic individuals and intrauterine insemination (IUI) candidate couples’ sperms.

Materials and Methods:

Samples were gathered from the patients referred to the Isfahan Infertility Center of Shahid Beheshti, 80 semen samples were in IUI candidates groups and 16 semen samples were in oligoasthenospermia group was collected. The outcome of IUI procedure was followed up after 14 days. Through these samples, 16 couples achieved pregnancy (IUI⁺) and from the top of the list, 16 semen samples with negative β-HCG were obtained (IUI⁻). After RNA extraction from sperms, PROTAMINE genes family expression was evaluated in our three groups by real time-reverse transcription polymerase chain reaction.

Results:

Our study revealed that P1 gene expression has no significant differences between IUI⁻, IUI⁺, and oligoasthenospermia groups, whereas P2 gene expression showed significant differences between oligoasthenospermia with two IUI groups. Main sperm parameters have no significant differences between IUI groups.

Conclusion:

This study reveals P1 and P2 genes expression value have no significant differences between IUI⁻ and IUI⁺. On the other hand, P2 gene expression value has significant differences between oligoasthenospermia with two IUI groups.

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.

Male factors in ART outcome prediction

Paternal influences on reproduction are significant causing about half of the infertile couples to turn to assisted reproductive techniques. Due to the increasing proportion of infertile couples adopting to conceive by in vitro fertilisation (IVF), predicting outcomes is of ever increasing importance. Since pregnancy rates following IVF are still quite low, prognostic information is very helpful in clinical decisions. Although significant research has been done on the maternal influence, male factor infertility is relatively understudied. To date, potential predictors include: method of fertilisation, age, reactive oxygen species, sperm quality parameters and DNA fragmentation. Predictors under investigation which show promising signs, even though there is no clear cut consensus on the predictive value to date include: folate and homocysteine, anti müllerian hormone measurement, environmental factors, body mass index, smoking, male age, stress, some subsets of antisperm antibodies and epigenetic features.

Follicular steroid hormones as markers of oocyte quality and oocyte development potential

CONTEXT:

Various components of follicular fluid are suggested as biochemical predictors of oocyte quality. Previous studies of follicular steroid hormone levels have shown disparate results when related with fertilization outcomes.

AIM:

The objective of the study was to relate the levels of steroid hormones of each individual follicle with oocyte maturation, fertilization results, embryo quality, and pregnancy rates.

SETTINGS AND DESIGN:

Prospective cohort study in a university hospital.

METHODS:

In 31 patients, who underwent intracytoplasmic sperm injection, it was performed an ultrasound guided aspiration of follicular fluid of the first two mature follicles from each ovary. Follicular levels of estradiol, progesterone, testosterone, and dehydroepiandrosterone sulfate were measured by chemiluminescent immunoassay.

STATISTICAL ANALYSIS:

Generalized estimating equation model.

RESULTS:

In follicular fluids with mature oocyte presence, in normal as well as in failed fertilization, there was a positive correlation between follicular testosterone and progesterone (r = 0.794, P = 0.0001 and r = 0.829, P = 0.0001). Progesterone levels were higher in cases of normal fertilization compared to failed fertilization (P = 0.003). B quality embryos came from oocytes immersed in follicular fluids with higher estradiol values and higher estradiol/progesterone and estradiol/testosterone ratios than those of C quality (P = 0.01; P = 0.0009; P = 0.001). Estradiol levels were higher in patients who achieved pregnancy (P = 0.02).

CONCLUSION:

The analysis of follicular hormone composition could be considered as an additional tool in oocyte selection.

Live birth after SrCl(2) oocyte activation in previous repeated failed or low fertilization rates after ICSI of frozen-thawed testicular spermatozoa: case report

PURPOSE

To report a live birth resulting after strontium chloride (SrCl(2)) oocyte activation in a couple with complete fertilization failure or low fertilization rates following intracytoplasmic sperm injection (ICSI) of frozen-thawed testicular spermatozoa.

METHODS

The couple underwent ICSI of frozen-thawed testicular spermatozoa. After ICSI, the oocytes were artificially activated by SrCl(2) because the results of fertilization were not satisfactory in the previous cycles. The main outcome measures were fertilization, pregnancy, and birth.

RESULTS

In the first and second cycles performed previously at another clinic, fertilization rates were 9.1 % and 0.0 %, respectively. In the third cycle, 31 metaphase II oocytes were retrieved. After sperm injection, all of the oocytes were stimulated using SrCl(2) for activation. Sixteen oocytes were fertilized (51.6 %), and a single embryo was transferred into the uterus on Day 3. A healthy girl weighing 2750 g was born at 40 weeks of gestation by caesarean section.

CONCLUSIONS

This result suggests that SrCl(2) could be useful for oocyte fertilization in case of repeated complete fertilization failure or low fertilization rates following ICSI of frozen-thawed testicular spermatozoa.

The association between severe obesity and characteristics of failed fertilized oocytes

STUDY QUESTION

Is the cytoskeletal and chromosomal organization of failed fertilized oocytes from severely obese patients (BMI ≥ 35 kg/m²) altered compared with that in patients with normal BMI (BMI 18.5-24.9 kg/m²)?

SUMMARY ANSWER

Compared with normal BMI patients, severe obesity was associated with a greater prevalence of spindle anomalies and non-aligned chromosomes in failed fertilized oocytes.

WHAT IS KNOWN AND WHAT THIS PAPER ADDS

Obesity is associated with poor reproductive outcomes, but little is known regarding the underlying mechanisms. To address potential mechanisms, our study compared the cytoskeletal and chromosome organization in failed fertilized oocytes from severely obese and normal BMI patients.

DESIGN

The study population was drawn from IVF patients treated in a hospital-based infertility clinic between February 2010 and July 2011. The prevalence of meiotic spindle and chromosome alignment anomalies in failed fertilized oocytes from patients with severe obesity (i.e. Class II and III; BMI 35.0-50.1 kg/m²) was compared with those from patients with normal BMI (BMI 18.5-24.9 kg/m²). Oocytes were fixed and then labeled for tubulin, actin and chromatin. Spindle number and integrity, as well as chromosome alignment, were assessed using immunofluorescence microscopy and, in some cases, confocal microscopy. Generalized estimating equations were applied, which account for the correlation among oocytes from the same patient to estimate odds ratio (OR), 95% confidence intervals (CIs) and two-sided Wald P-values. Models were adjusted for continuous age at cycle start, cycle type (IVF or ICSI) and polycystic ovarian syndrome (PCOS) a priori.

PARTICIPANTS AND SETTING

University-affiliated infertility clinic. A total of 276 oocytes that failed to fertilize from 137 patients were evaluated: 105 oocytes from severely obese women (n = 47) and 171 oocytes from normal BMI patients (n = 90).

MAIN RESULTS AND THE ROLE OF CHANCE

(i) Significantly more oocytes from the severely obese group exhibited two spindles compared with those from the normal BMI group (58.9 versus 35.1%; OR = 2.68, CI = 1.39-5.15, P-value = 0.003). (ii) Among oocytes with a single spindle, those from severely obese patients showed a significantly higher prevalence of disarranged spindles with non-aligned chromosomes compared with those from normal BMI patients (28.6 versus 8.6%; OR = 4.58, CI = 1.05-19.86, P-value = 0.04).

BIAS, CONFOUNDING AND OTHER REASONS FOR CAUTION

Inclusion of only failed fertilized oocytes, small sample size, unknown factors such as non-PCOS comorbidity.

GENERALIZABILITY TO OTHER POPULATIONS

For this study, by design, it is unclear whether the findings are generalizable to successfully fertilized oocytes, and whether this oocyte-level influence of obesity is generalizable to infertile women who do not undergo stimulation or, more broadly, to spontaneous conceptions in fertile women.

STUDY FUNDING/COMPETING INTEREST(S)

none.

TRIAL REGISTRATION NUMBER

n/a.

Importance of sperm gluthatione treatment in ART

PURPOSE

The aim of this study was to investigate whether treatment of sperm from infertile patients would gluthatione could reduce sperm premature chromosome condensation (PCC). To reach the goals of this study, the frequency of sperm PCC formation in sperm of normal and sub-fertile men with/without glutathione treatment were compared and analyzed.

METHODS

Hamster oocytes were retrieved after super ovulation by PMSG and HCG injection. Following treatment with hyaluronidase, zonae was removed by trypsin digestion. Sperm were classified into 3 groups according to morphology, movement and counts, treated with glutathione(10 μg/ml) and then processed by swim up method. After capacitation, zona-free oocytes were incubated with sperm then transferred to fresh media containing colcemid. Cells were fixed and slides prepared using Tarkowskie's standard air drying technique and after staining in 5% Giemsa, oocytes were analyzed at high magnification.

RESULTS

Sperm penetration rate was higher and the rate of intact sperm head and PCC was lower in GSH treated samples compared to non treated groups. Sperm penetration rate was significantly higher in treated astheno sperm samples compared to non-treated ones (66.4% and 50. 97% respectively) (P < 0.001). We observed a significantly higher PCC frequency in infertile patients (P < 0.001). In addition, there was a significantly lower rate of intact sperm head in treated astheno sperm samples (17.49%) compared to non treated ones (26.79%) (P < 0.001). Finally, a significantly lower rate of PCC in treated astheno sperm samples comparing to non treated ones was seen (51.06% and 72.96% respectively) (P < 0. 001).

CONCLUSIONS

Our results show that sperm PCC formation could be one of the major causes of failed fertilization in individuals with sperm abnormalities. Also sperm PCC formation may be involved in the etiology of some cases of idiopathic infertility. Given that the susceptibility of sperm to oxidative stress is significantly greater in idiopathic infertile men, our results show that treatment with glutathione could significantly reduce these stress factors and increase ART outcome.

Artificial oocyte activation and human failed-matured oocyte vitrification followed by in vitro maturation

The investigation presented in this paper was conducted on the effect of oocytes activation on frozen–thawed human immature oocytes followed by in vitro maturation (IVM). A total of 386 failed-matured oocytes (germinal vesicle (GV) and metaphase I (MI) stages) was randomly divided into two groups: fresh group and vitrification group, GV group and MI group, respectively). The matured oocytes were subject to intracytoplasmic sperm injection (ICSI) after IVM had been carried out. The vitrification group was randomly divided into two groups: controlled and artificial oocyte activation (AOA). The injected oocytes in the controlled group were cultured in cleavage medium. The AOA group oocytes were activated by exposing them to 7% anhydrous alcohol for 6 min then cultured in cleavage medium as well. The rates of fertilization and early embryonic development were compared between the controlled and AOA groups. In MI vitrification group, the high-quality embryo formation rate and blastocyst formation rate were significantly higher in the AOA group than in the controlled group (P < 0.01). In the GV vitrification group, the high-quality embryo formation rate was significantly higher in the AOA group than in the controlled group (P < 0.05). These results indicate that AOA may be good for early embryonic development of vitrified immature human oocytes.

Gas6 downregulation impaired cytoplasmic maturation and pronuclear formation independent to the MPF activity

Previously, we found that the growth arrest-specific gene 6 (Gas6) is more highly expressed in germinal vesicle (GV) oocytes than in metaphase II (MII) oocytes using annealing control primer (ACP)-PCR technology. The current study was undertaken to investigate the role of Gas6 in oocyte maturation and fertilization using RNA interference (RNAi). Interestingly, despite the specific and marked decrease in Gas6 mRNA and protein expression in GVs after Gas6 RNAi, nuclear maturation including spindle structures and chromosome segregation was not affected. The only discernible effect induced by Gas6 RNAi was a change in maturation promoting factor (MPF) activity. After parthenogenetic activation, Gas6 RNAi-treated oocytes at the MII stage had not developed further and arrested at MII (90.0%). After stimulation with Sr(2+), Gas6-silenced MII oocytes had markedly reduced Ca(2+) oscillation and exhibited no exocytosis of cortical granules. In these oocytes, sperm penetration occurred during fertilization but not pronucleus (PN) formation. By roscovitine and colcemid treatment, we found that the Gas6 knockdown affected cytoplasmic maturation directly, independent to the changed MPF activity. These results strongly suggest that 1) the Gas6 signaling itself is important to the cytoplasmic maturation, but not nuclear maturation, and 2) the decreased Gas6 expression and decreased MPF activity separately or mutually influence sperm head decondensation and PN formation.

Birth and follow-up of babies born following ICSI using SrCl2 oocyte activation

This report describes six successful pregnancies (five healthy children from four deliveries and two miscarriages) with SrC1(2) oocyte activation using spermatozoa from nine patients with repeated fertilization failure. Oocytes were artificially activated by SrC1(2) 30 min after intracytoplasmic sperm injection (ICSI). Oocytes were placed in 10 mmol/l of SrC1(2) medium for 1 h, rinsed several times, and then cultured in Universal IVF medium. Developmental characteristics of five resulting children until 1 year old were assessed according to the maternal and children health hand book issued by Mothers' and Children's Health Organization in Japan. Mean fertilization rate, mean frequency of good cleaved embryos, pregnancy rate, and implantation rate after artificial activation in nine couples were increased from 21.7 to 64.5% (P < 0.001), from 0 to 15.4%, from 0 to 40.0% and from 0 to 25.0% respectively. Five healthy children were born following ICSI and artificial activation between February 2005 and March 2006. Physical and mental development of the children from birth to 12 months was normal. These suggest the utility and safety of SrCl(2) for patients with repeated failed fertilizations following ICSI and artificial activation.

Developmental competence of immature and failed/abnormally fertilized human oocytes in nuclear transfer

Somatic cell nuclear transfer holds great promise for basic studies of reprogramming human somatic cells and for the potential development of novel cell-based therapeutics. The aim of this study was to examine experimental aspects of human nuclear transfer via use of an abundant source of oocytes, those that are routinely discarded from assisted reproduction clinics. The results suggest and reinforce several findings based on the analysis of multiple parameters: first, it was observed that supplementation of commercial culture media with hormones promoted embryo development after parthenogenetic activation. Second, the use of the chemical activation reagent puromycin resulted in significant differences in cleavage rates in oocytes that were failed/abnormally fertilized after intracytoplasmic sperm injection relative to those from IVF (P < 0.05). Third, cycloheximide promoted cleavage rates >/=40% in both groups of oocytes; moreover, two blastocysts were produced following cycloheximide treatment. Finally, the use of a subset of oocytes for nuclear transfer resulted in cleaved embryos that expressed green fluorescent protein from a transgene in donor nuclei from human embryonic stem cells. In light of these results, it is suggested that the discarded oocytes can be used to investigate new human nuclear transfer protocols for embryonic stem cell derivation.

Artificial oocyte activation with calcium ionophore A23187 in intracytoplasmic sperm injection cycles using surgically retrieved spermatozoa

OBJECTIVE

To evaluate the effect of artificial oocyte activation (AOA) on intracytoplasmic sperm injection (ICSI) cycles using surgically retrieved sperm.

DESIGN

Laboratory study.

SETTING

Fertility/assisted fertilization center.

PATIENT(S)

Couples undergoing surgical sperm retrieval for ICSI (n = 204).

INTERVENTION(S)

Application of calcium ionophore A23187 for AOA.

MAIN OUTCOME MEASURE(S)

Cycles were divided into experimental groups according to the origin of the sperm used for injection and the type of azoospermia: [1] testicular sperm aspiration in nonobstructive-azoospermic patients (TESA-NOA group, n = 58), [2] TESA in obstructive-azoospermic patients (TESA-OA group, n = 48), [3] and percutaneous epididymal sperm aspiration in obstructive-azoospermic patients (PESA-OA, n = 98). For each experimental group, cycles where AOA was applied (subgroup: activation) were compared with cycles in which AOA was not applied (subgroup: control). The fertilization, high-quality embryo, implantation, and pregnancy rates were compared among the subgroups.

RESULT(S)

For patients undergoing TESA, AOA did not improve ICSI outcomes for either type of azoospermia. However, for cases in which the injected sperm were retrieved from the epididymis, a statistically significantly increased rate of high-quality embryos was observed with AOA.

CONCLUSION(S)

Artificial oocyte activation may improve ICSI outcomes in azoospermic patients when epididymal, but not testicular spermatozoa, are injected.

The protamine family of sperm nuclear proteins

An overview of the vertebrate members of a diverse family of basic DNA-binding proteins that are synthesized in the late-stage spermatids of many animals and plants and condense the spermatid genome into a genetically inactive state.

The protamines are a diverse family of small arginine-rich proteins that are synthesized in the late-stage spermatids of many animals and plants and bind to DNA, condensing the spermatid genome into a genetically inactive state. Vertebrates have from one to 15 protamine genes per haploid genome, which are clustered together on the same chromosome. Comparison of protamine gene and amino-acid sequences suggests that the family evolved from specialized histones through protamine-like proteins to the true protamines. Structural elements present in all true protamines are a series of arginine-rich DNA-anchoring domains (often containing a mixture of arginine and lysine residues in non-mammalian protamines) and multiple phosphorylation sites. The two protamines found in mammals, P1 and P2, are the most widely studied. P1 packages sperm DNA in all mammals, whereas protamine P2 is present only in the sperm of primates, many rodents and a subset of other placental mammals. P2, but not P1, is synthesized as a precursor that undergoes proteolytic processing after binding to DNA and also binds a zinc atom, the function of which is not known. P1 and P2 are phosphorylated soon after their synthesis, but after binding to DNA most of the phosphate groups are removed and cysteine residues are oxidized, forming disulfide bridges that link the protamines together. Both P1 and P2 have been shown to be required for normal sperm function in primates and many rodents.

Paternal effects on early embryogenesis

Historically, less attention has been paid to paternal effects on early embryogenesis than maternal effects. However, it is now apparent that certain male factor infertility phenotypes are associated with increased DNA fragmentation and/or chromosome aneuploidies that may compromise early embryonic development. In addition, there is a growing body of evidence that the fertilizing sperm has more function than just carrying an intact, haploid genome. The paternally inherited centrosome is essential for normal fertilization, and the success of higher order chromatin packaging may impact embryogenesis. Epigenetic modifications of sperm chromatin may contribute to the reprogramming of the genome, and sperm delivered mRNA has also been hythesized to be necessary for embryogenesis. There is less information about the epigenetic factors affecting embryogenesis than genetic factors, but the epigenetics of gamete and early embryogenesis is a rapidly advancing field.