Embryonic development in vitro is compromised by the ICSI procedure

Predictive Factors for the Formation of Viable Embryos in Subfertile Patients with Diminished Ovarian Reserve: A Clinical Prediction Study

This study aims to construct and validate a nomogram for predicting blastocyst formation in patients with diminished ovarian reserve (DOR) during in vitro fertilization (IVF) procedures. A retrospective analysis was conducted on 445 DOR patients who underwent in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) at the Reproductive Center of Yulin Maternal and Child Health Hospital from January 2019 to January 2023. A total of 1016 embryos were cultured for blastocyst formation, of which 487 were usable blastocysts and 529 did not form usable blastocysts. The embryos were randomly divided into a training set (711 embryos) and a validation set (305 embryos). Relevant factors were initially identified through univariate logistic regression analysis based on the training set, followed by multivariate logistic regression analysis to establish a nomogram model. The prediction model was then calibrated and validated. Multivariate stepwise forward logistic regression analysis showed that female age, normal fertilization status, embryo grade on D2, and embryo grade on D3 were independent predictors of blastocyst formation in DOR patients. The Hosmer-Lemeshow test indicated no statistical difference between the predicted probabilities of blastocyst formation and actual blastocyst formation (P > 0.05). These results suggest that female age, normal fertilization status, embryo grade on D2, and embryo grade on D3 are independent predictors of blastocyst formation in DOR patients. The clinical prediction nomogram constructed from these factors has good predictive value and clinical utility and can provide a basis for clinical prognosis, intervention, and the formulation of individualized medical plans.

Comparison of clinical outcomes between conventional in vitro fertilization and intracytoplasmic sperm injection in poor responders with only single oocyte retrieved

OBJECTIVE

To compare the clinical outcomes between conventional insemination (IVF) and intracytoplasmic sperm injection (ICSI) in poor responders with only a single oocyte retrieved.

MATERIALS AND METHODS

This is a retrospective case-control study. Couples who were treated with assisted reproductive technology (ART) with a single oocyte retrieved in Mackay Memorial Hospital from 1996 to 2016 were recruited. All data were categorized into three groups, according to their fertilization method and semen quality: group A, conventional insemination with non-male factor (IVF-NMF, n = 115), group B, ICSI with male factor (ICSI-MF, n = 30), and group C, ICSI with non-male factor (ICSI-NMF, n = 49).

RESULTS

No statistically significant difference was observed between IVF and ICSI groups in pregnancy outcomes, including the chemical or clinical pregnancy rate, miscarriage rate, and live birth rate. Similar fertilization rates per oocyte obtained were observed in IVF and ICSI patients, but significantly lower per mature oocyte in the ICSI group (IVF: 91.5%, ICSI-MF: 75.0%, ICSI-NMF: 77.8%). Although there is no statistical significance, the lower live birth rate is observed in group C than others (A:11.5%, B:25%, C:5%, p = 0.187).

CONCLUSION

In this study, pregnancy outcomes of conventional in vitro fertilization and ICSI in poor responders with only a single oocyte retrieved were similar. However, the fertilization rate of matured oocytes in ICSI groups is significantly lower than that in the IVF group, indicating that ICSI procedures might cause oocyte damage. Therefore, the choice of fertilization method should be based on semen quality. A randomized controlled trial should be performed to confirm our findings.

Intracytoplasmic sperm injection vs. conventional in vitro fertilization in patients with non-male factor infertility

OBJECTIVE

To compare the cumulative live birth rates (CLBRs) and cost effectiveness of intracytoplasmic sperm injection (ICSI) and conventional in vitro fertilization (cIVF) for non-male factor infertility.

DESIGN

A retrospective cohort study.

SETTING

Society for Assisted Reproductive Technology clinics.

PATIENT(S)

A total of 46,967 patients with non-male factor infertility with the first autologous oocyte retrieval cycle between January 2014 and December 2015.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The primary outcomes were CLBR, defined as up to 1 live birth from an autologous retrieval cycle between 2014 and 2015, and linked fresh and frozen embryo transfers through 2016. The secondary outcomes included miscarriage rate, 2 pronuclei per oocyte retrieved, and the total number of transferred and frozen embryos. Analyses were performed on subsamples with and without preimplantation genetic testing for aneuploidy (PGT-A). A cost analysis was performed to determine the costs accrued by ICSI.

RESULT(S)

Among cycles without PGT-A in patients with non-male factor infertility, the CLBR was 60.9% for ICSI cycles vs. 64.3% for cIVF cycles, a difference that was not significantly different after adjustment for covariates (adjusted risk ratio, 0.99; 95% confidence interval, 0.99-1.00). With PGT-A, no difference in CLBR was found between ICSI and cIVF cases after adjustment (64.7% vs. 69.0%, respectively; adjusted risk ratio, 0.97; 95% confidence interval, 0.93-1.01). The patients were charged an estimated additional amount of $37,476,000 for ICSI without genetic testing and an additional amount of $7,213,500 for ICSI with PGT-A over 2 years by Society for Assisted Reproductive Technology clinics.

CONCLUSION(S)

In patients with non-male factor infertility, ICSI did not improve CLBR. Given the additional cost and the lack of CLBR benefit, our data show that the routine use of ICSI in patients with non-male factor infertility is not warranted.

The impact of blastomere loss on pregnancy and neonatal outcomes of vitrified-warmed Day3 embryos in single embryo transfer cycles

BACKGROUND

Blastomere loss is a common phenomenon that occurs following cryopreservation. To date, studies have drawn conflicting conclusions regarding the impact of blastomere loss on pregnancy outcomes. Besides, limited information is available concerning the neonatal safety of embryos with blastomere loss. In the present study, we aimed to investigate the impact of blastomere loss on pregnancy and neonatal outcomes of vitrified/warmed Day3 cleavage-stage embryos in single embryo transfer cycles.

METHODS

This retrospective cohort study included all vitrified/warmed D3 cleavage-stage single frozen-thawed embryo transfer (FET) cycles between April 2015 and February 2021. We compared pregnancy and subsequent neonatal outcomes between the intact embryos group and the blastomere loss group in single FET cycles.

RESULTS

A total of 6287 single FET cycles were included in the study, in which 5873 cycles were classified into the intact embryo group and 414 cycles were classified into the blastomere loss group. The outcomes of the blastomere loss group were significantly inferior to those of the intact embryo group, in terms of implantation/biochemical pregnancy/clinical pregnancy/ongoing pregnancy rate and live birth rate per embryo transfer cycle/per clinical pregnancy. Further binary logistic regression confirmed that blastomere loss was negatively associated with live birth. Moreover, the blastomere loss group presented with an elevated early miscarriage rate. The neonatal conditions were broadly similar between the two groups. Additionally, multiple binary logistic regression analysis demonstrated that primary infertility and intracytoplasmic sperm injection (ICSI) were common influencing factors of blastomere loss (aOR 1.447, 95% CI 1.038-2.019, P = 0.029; aOR: 1.388, 95% CI: 1.044-51.846, P = 0.024).

CONCLUSIONS

The transfer of vitrified/warmed D3 embryos with blastomere loss is related to impaired embryo developmental potentials and reduced probabilities of conception. Moreover, even if the embryos with blastomere loss have implanted and reached clinical pregnancies, they present with a lower possibility of developing to live birth owing to a higher early miscarriage rate. However, once the embryos with blastomere loss result in a live birth, no adverse neonatal outcomes are observed. Primary infertility and ICSI were found to be risk factors for blastomere loss.

High concentration of dopamine treatment may induce acceleration of human sperm motility

Purpose

In humans, catecholamines (including dopamine) have been identified in semen and fallopian tubes, while dopamine D2 receptors (D2DR) are found in the sperm midpiece region. How dopamine dose affects human sperm function and whether dopamine treatment is useful in assisted reproductive technology is unclear.

Methods

Sperm samples were obtained from patients with normal semen parameters undergoing fertility treatment. We investigated the effects of dopamine treatment on tyrosine phosphorylation and sperm motility. Sperm motility was analyzed using the computer-assisted sperm analysis (CASA) system.

Results

This study revealed that various dopamine concentrations (0.1-100 μM) did not increase sperm tyrosine phosphorylation. Progressive motility increased substantially when treated with high concentrations of dopamine (10 and 100 μM) and was blocked by raclopride (a D2DR antagonist). After 24-h sperm culture, the addition of 10 μM dopamine significantly increased curvilinear velocity and amplitude of lateral head displacement, which are indicators of hyperactivation.

Conclusion

Dopamine did not affect tyrosine phosphorylation, but increased sperm motility. High concentrations of dopamine were more effective to accelerate sperm motility in cases where sperm motile capacity was low.

The Impact of Intracytoplasmic Sperm Injection in Non-Male Factor Infertility-A Critical Review

Intracytoplasmic sperm injection (ICSI) was originally designed to overcome barriers due to male factor infertility. However, a surveillance study found that ICSI use in non-male factor infertility increased from 15.4% to 66.9% between 1996 and 2012. Numerous studies have investigated fertilization rate, total fertilization failure, and live birth rate per cycle (LBR), comparing the use of ICSI versus conventional in vitro fertilization (IVF) for non-male factor infertility. The overwhelming conclusion shows no increase in fertilization rate or LBR per cycle with the use of ICSI for non-male factor infertility. The overuse of ICSI is likely related to the desire to avoid a higher rate of total fertilization failure in IVF. However, data supporting the benefit of using ICSI for non-male factor infertility is lacking, and 33 couples would need to be treated with ICSI unnecessarily to avoid one case of total fertilization failure. Such practice increases the cost to the patient, increases the burden on embryologist’s time, and is a misapplication of resources. Additionally, there remains conflicting data regarding the safety of offspring conceived by ICSI and potential damage to the oocyte. Thus, the use of ICSI should be limited to those with male factor infertility or a history of total fertilization factor infertility due to uncertainties of potential adverse impact and lack of proven benefit in non-male factor infertility.

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.

ICSI Does Not Improve Live Birth Rates but Yields Higher Cancellation Rates Than Conventional IVF in Unexplained Infertility

Objectives: Unexplained infertility has been one of the indications for utilization of intracytoplasmic sperm injection (ICSI). However, whether ICSI should be preferred to IVF for patients with unexplained infertility remains an open question. This study aims to determine if ICSI improves the clinical outcomes over conventional in vitro fertilization (IVF) in couples with unexplained infertility.

Methods: This was a retrospective cohort study of 549 IVF and 241 ICSI cycles for patients with unexplained infertility at a fertility center of a university hospital from January 2016 and December 2018. The live birth rate and clinical pregnancy rate were compared between the two groups. Other outcome measures included the implantation rate, miscarriage rate, and fertilization rate.

Results: The live birth rate was 35.2% (172/488) in the IVF group and 33.3% (65/195) in ICSI group, P = 0.635. The two groups also had similar clinical pregnancy rates, implantation rates, and miscarriage rates. The fertilization rate of IVF group was significantly higher than that of ICSI group (53.8 vs. 45.7%, P = 0.000, respectively). Sixty-one and 46 patients did not transfer fresh embryos in IVF and ICSI cycles, respectively. Patients with IVF cycles had lower cancellation rates than those with ICSI (11.1 vs. 19.1%, P = 0.003, respectively).

Conclusion: ICSI does not improve live birth rates but yields higher cancellation rates than conventional IVF in the treatment of unexplained infertility.

Is intracytoplasmic sperm (ICSI) better than traditional in vitro fertilization (IVF): confirmation of higher blastocyst rates per oocyte using a split insemination design

PURPOSE

To explore the effects of traditional vs. intracytoplasmic sperm injection (ICSI) insemination method on the outcome of high-quality blastocyst development in a split sibling oocyte cohort.

METHODS

In this retrospective cohort study, we analyzed 62 ICSI/IVF split cycles. Sibling oocytes were randomly assigned to ICSI or IVF insemination. Two hundred thirty-four ICSI-only cycles and 152 IVF-only cycles were also analyzed for comparison. Blastocysts were graded by Gardner's embryo grading and were considered a high-quality blastocyst if 3BB or better (Gardner 1999).

RESULTS

In the ICSI/IVF split group, (1) ICSI oocytes had a higher fertilization rate per oocyte allocated (73% vs 62%, p < 0.001), (2) more high-quality day 2 embryos (69% vs 55%, p < 0.005), (3) ICSI oocytes had a lower blastulation rate per 2PN (46% vs 54%, p < 0.05), but a higher blastulation rate when calculated per oocyte allocated (40% vs 32%, p < 0.05). The ICSI-only group had a lower fertilization rate (65% vs 70%, p < 0.001) but more high-quality day 2 embryos in comparison to the IVF-only group (68% vs 64%, p < .05). The total high-quality blastulation rate was higher for the IVF-only group per 2PN (49% vs 43%, p < 0.05) and per oocyte retrieved (34% vs 28%, p < 0.05).

CONCLUSIONS

This distinctive IVF/ICSI sibling oocyte split design demonstrated a higher-quality blastulation rate in the IVF group compared to the ICSI group when calculated per 2PN, but not per oocyte allocated to each insemination procedure.

Metabolic profile of in vitro derived human embryos is not affected by the mode of fertilization

The pattern of metabolism by early embryos in vitro has been linked to a range of phenotypes, including viability. However, the extent to which metabolic function of embryos is modified by specific methods used during ART has yet to be fully described. This study has sought to determine if the mode of fertilization used to create embryos affects subsequent embryo metabolism of substrates. A metabolic profile, including consumption of key substrates and the endogenous triglyceride content of individual IVF and ICSI supernumerary embryos, was assessed and compared. Embryo development and quality was also recorded. All embryos were donated at a single clinical IVF center, on Day 5, from 36 patients aged 18-38 years, The data revealed that consumption of glucose and pyruvate, and production of lactate, did not differ between embryos created by IVF or ICSI. Similarly, the mode of insemination did not impact on the triglyceride content of embryos. However, ICSI-derived embryos displayed a more active turnover of amino acids (P = 0.023), compared to IVF embryos. The specific amino acids produced in higher quantities from ICSI compared to IVF embryos were aspartate (P = 0.016), asparagine (P = 0.04), histidine (P = 0.021) and threonine (P = 0.009) while leucine consumption was significantly lower (P = 0.04). However, importantly neither individual nor collective differences in amino acid metabolism were apparent for sibling oocytes subjected to either mode of fertilization. Embryo morphology (the number of top grade embryos) and development (proportion reaching the blastocyst stage) were comparable in patients undergoing IVF and ICSI. In conclusion, the microinjection of spermatozoa into oocytes does not appear to have an impact on subsequent metabolism and viability. Observed differences in amino acid metabolism may be attributed to male factor infertility of the patients rather than the ICSI procedure per se.

Predictors of blastocyst formation rate in elective day 5 transfer cycle

This study aimed to investigate the factors affecting blastocyst formation rate. One hundred and seven fresh in vitro fertilisation (IVF) and elective day 5 blastocyst transfer cycles were selected. Univariate and multivariate analyses revealed that intracytoplasmic sperm injection (ICSI) (r = -.236, p = .014 vs. p = .005) was advantageous for blastocyst formation. In addition, the number of mature oocytes (r = -.274, p = .004 vs. p = .002) was a significant factor associated with blastocyst and good-quality blastocyst formation rates (p = .021, r = -.389). Both blastocyst and good-quality blastocyst formation rates were significantly higher with ICSI than with conventional insemination (65.0 ± 24.5% vs. 50.0 ± 21.2%, p = .012; 43.1 ± 22.8% vs. 30.9 ± 19.8%, p = .038, respectively). The number of mature oocytes appears to be the most important predictor of blastocyst formation rate. Additionally, ICSI fertilisation is superior to conventional insemination in terms of blastocyst formation rate.IMPACT STATEMENTWhat is already known on this subject? There are many advantages of blastocyst transfer cycle over cleavage transfer cycle, but there are no known routine selection criteria for the timing of embryo transfer. To date, the number of blastomeres, number of retrieved oocytes, quality of embryos and fertilisation method have been suggested as the important factors involved in blastocyst formation. However, the number of studies on this issue is limited, and some studies have shown conflicting results.What do the results of this study add? This study showed that the number of mature oocytes and ICSI fertilisation are the significant factors associated with blastocyst formation rate in elective day 5 transfer cycle.What are the implications of these findings for clinical practice and/or further research? This paper demonstrated that the number of mature oocytes and the fertilisation method should be considered before embryo transfer. Consideration of these factors would be meaningful in selecting patients who will be suitable for extended culture up to day 5.

Failure of complete hatching of ICSI-derived human blastocyst by cell herniation via small slit and insufficient expansion despite ongoing cell proliferation

PURPOSE

To assess the effect of intracytoplasmic sperm injection (ICSI) on embryo hatching and visualise the effects of zona thinning (ZT) on the embryo using time-lapse monitoring.

METHODS

In vitro fertilisation (IVF) (n = 178) and ICSI (n = 110)-derived cryopreserved blastocysts were donated by patients who previously had a baby. This study investigated the impacts of IVF, ICSI, laser-assisted hatching by ZT and formation of ICSI penetration trace on zona pellucida of IVF-derived blastocyst on blastcyst diameter, the estimated number of trophectoderm (TE) cells and completed hatching rate.

RESULTS

The completed hatching rate and diameters of the completely hatched blastocysts at hatching commencement and at the maximum expansion were significantly greater in the IVF than in ICSI groups. The completed hatching rate significantly increased with ZT in both groups. The maximum diameters of the completely hatched blastocysts were significantly smaller in the ZT than in non-ZT groups. The estimated TE cell numbers increased from hatching commencement to their maximum expansion points. The incompletely hatched ICSI-derived blastocysts intermittently herniated cells via small slits until degeneration. The completed hatching rate significantly decreased by the formation of ICSI penetration trace on zona pellucida of IVF-derived blastocyst.

CONCLUSION

ICSI-derived blastocysts intermittently release proliferating cells and extracted TE cells and/or inner cell masses via a small slit; thus, blastocyst expansion is not sufficiently increased, leading to a reduced complete hatching rate. Therefore, the ICSI penetration trace potentially has negative effects on blastocyst expansion process in vitro and is a risk factor for the failure of completed hatching.

Fertility and Neonatal Outcomes of Freeze-All vs. Fresh Embryo Transfer in Women With Advanced Endometriosis

Background: Eutopic endometrium from women with endometriosis has functional changes in several aspects, which may largely account for the decrease in the quality of endometrial receptivity. It is of utmost importance to know whether freeze-all strategy can restore optimal receptivity in endometriotic women leading to the better ART outcomes. Methods: Retrospective study involved patients with advanced endometriosis undergoing first embryo transfer cycles during the period from March 2006 to March 2017 at a tertiary care center. After propensity score matching, there were 506 women in the freeze-all group and 255 women in fresh group. Our main outcomes included the rates of implantation, clinical pregnancy, and live birth. Subgroup analyses were performed after stratification by the number of oocytes retrieved and fertilization method. Neonatal outcomes included gestational age and birth weight z-score for singletons and multiple births. Results: In our matched cohort, the implantation, clinical pregnancy and live birth rates were statistically significantly higher in the freeze-all group compared with fresh transfer groups (34.4 vs. 25.5%, 51.8 vs. 38.8%, and 45.3 vs. 31.8%, all P < 0.001, respectively). A more beneficial effect of freeze-all cycles was found in patients who got more than 15 oocytes. Additionally, when ICSI insemination techniques were used to achieve fertilization, the advantage of freeze-all strategy was not obvious. Assessment of 382 babies showed no statistically significant difference in the mode of delivery, sex of live-born, gestational age, unadjusted median birth weight, and z-score between two study groups. Conclusion: Freeze-all strategy is an attractive option to improve the outcomes of ART for women with advanced endometriosis.

Tolerance of lamb and mouse oocytes to cryoprotectants during vitrification

SummaryMouse and lamb oocytes were vitrified with, or exposed to, different cryoprotectants and evaluated for their effects on their survival and developmental competence after in vitro fertilization (IVF) and activation treatments. Control oocytes remained untreated, whilst the remainder were exposed to three different combinations of vitrification solutions [dimethyl sulfoxide (DMSO) + ethylene glycol (EG), EG only, or propanediol (PROH) + EG] and either vitrified or left unfrozen (exposed groups). Oocytes in the control and vitrified groups underwent IVF and developmental competence was assessed to the blastocyst stage. In lambs, survival rate in vitrified oocytes was significantly lower than for oocytes in the exposed groups (P &lt;0.05). Blastocyst development was low in vitrified oocytes compared with controls (&lt;6% vs 38.9%, P &lt;0.01). Parthenogenetic activation was more prevalent in vitrified lamb oocytes compared with controls (P &lt;0.05). No evidence of zona pellucida hardening or cortical granule exocytosis could account for reduced fertilization rates in vitrified lamb oocytes. Mouse oocytes demonstrated a completely different response to lamb oocytes, with survival and parthenogenetic activation rates unaffected by the vitrification process. Treatment of mouse oocytes with DMSO + EG yielded significantly higher survival and cleavage rates than treatment with PROH + EG (87.8% and 51.7% vs 32.7% and 16.7% respectively, P &lt;0.01), however cleavage rate for vitrified oocytes remained lower than for the controls (51.7% vs 91.7%, P &lt;0.01) as did mean blastocyst cell number (33 ± 3.1 vs 42 ± 1.5, P &lt;0.05). From this study, it is clear that lamb and mouse show different tolerances to cryoprotectants commonly used in vitrification procedures, and careful selection and testing of species-compatible cryoprotectants is required when vitrifying oocytes to optimize survival and embryo development.

Influence of the insemination method on the outcomes of elective blastocyst culture

Objective

The aim of this study was to explore the effects of the insemination method on the outcomes of elective blastocyst culture.

Methods

We retrospectively analyzed the outcomes of elective blastocyst culture performed between January 2011 and December 2014.

Results

There were 2,003 cycles of conventional in vitro fertilization (IVF) and 336 cycles of intracytoplasmic sperm injection (ICSI), including 25,652 and 4,164 embryos that underwent sequential blastocyst culture, respectively. No significant differences were found in the female patients' age, basal follicle-stimulating hormone level, basal luteinizing hormone level, body mass index, number of oocytes, maturity rate, fertilization rate, or good-quality embryo rate. However, the blastocyst formation rate and embryo utilization rate were significantly higher in the conventional IVF group than in the ICSI group (54.70% vs. 50.94% and 51.09% vs. 47.65%, respectively, p<0.05). The implantation/pregnancy rate (IVF, 50.93%; ICSI, 55.10%), miscarriage rate (IVF, 12.57%; ICSI, 16.29%), and live birth rate (IVF, 42.12%; ICSI, 44.08%) were similar (p>0.05). No cycles were canceled due to the formation of no usable blastocysts.

Conclusion

Although the fertilization method had no effect on clinical outcomes, the blastocyst formation rate and embryo utilization rate in the ICSI group were significantly lower than those observed in the conventional IVF group. Therefore, more care should be taken when choosing to perform blastocyst culture in ICSI patients.

Clinical outcomes after IVF or ICSI using human blastocysts derived from oocytes containing aggregates of smooth endoplasmic reticulum

In this study the clinical and neo-natal outcomes after transfer of blastocysts derived from oocytes containing aggregates of smooth endoplasmic reticulum (SER) were compared between IVF and intracytoplasmic sperm injection (ICSI) cycles. Clinical and neo-natal outcomes of blastocysts in cycles with at least one SER metaphase II oocyte (SER + MII; SER + cycles) did not significantly differ between the two insemination methods. When SER + MII were cultured to day 5/6, fertilization, embryo cleavage and blastocyst rates were not significantly different between IVF and ICSI cycles. In vitrified-warmed blastocyst transfer cycles, the clinical pregnancy rates from SER + MII in IVF and ICSI did not significantly differ. In this study, 52 blastocysts (27 IVF and 25 ICSI) derived from SER + MII were transferred, yielding 15 newborns (5 IVF and 10 ICSI) and no malformations. Moreover, 300 blastocysts (175 IVF and 125 ICSI) derived from SER-MII were transferred, yielding 55 newborns (24 IVF and 31 ICSI cycles). Thus, blastocysts derived from SER + cycles exhibited an acceptable ongoing pregnancy rate after IVF (n = 125) or ICSI (n = 117) cycles. In conclusion, blastocysts from SER + MII in both IVF and ICSI cycles yield adequate ongoing pregnancy rates with neo-natal outcomes that do not differ from SER-MII.

In vitro matured oocytes are more susceptible than in vivo matured oocytes to mock ICSI induced functional and genetic changes

Background

Concerns regarding the safety of ICSI have been intensified recently due to increased risk of birth defects in ICSI born children. Although fertilization rate is significantly higher in ICSI cycles, studies have failed to demonstrate the benefits of ICSI in improving the pregnancy rate. Poor technical skill, and suboptimal in vitro conditions may account for the ICSI results however, there is no report on the effects of oocyte manipulations on the ICSI outcome.

Objective

The present study elucidates the influence of mock ICSI on the functional and genetic integrity of the mouse oocytes.

Methods

Reactive Oxygen Species (ROS) level, mitochondrial status, and phosphorylation of H2AX were assessed in the in vivo matured and IVM oocytes subjected to mock ICSI.

Results

A significant increase in ROS level was observed in both in vivo matured and IVM oocytes subjected to mock ICSI (P<0.05-0.001) whereas unique mitochondrial distribution pattern was found only in IVM oocytes (P<0.01-0.001). Importantly, differential H2AX phosphorylation was observed in both in vivo matured and IVM oocytes subjected to mock ICSI (P <0.001).

Conclusion

The data from this study suggests that mock ICSI can alter genetic and functional integrity in oocytes and IVM oocytes are more vulnerable to mock ICSI induced changes.

Embryo selection strategy in sibling oocytes: a novel approach to measuring the likelihood of single‑embryo transfer using a mouse embryo transfer model

The present study investigated the effect of embryo transfer on post-implantation development using different fertilization approaches in sibling oocyte procedures. C57BL/6, DBA/2, C3H/HeJ and ICR mice were used at 8-10 weeks of age. Mature oocytes were collected, divided into two groups and fertilized using in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Different numbers of the resulting blastocysts were then transferred into recipients and designated as either: The single embryo transfer (SET) I model (one transferred embryo), the SET II model (six transferred embryos) or the multiple embryo transfer (MET) model (24 transferred embryos). The development efficiency, cell number, number of apoptotic cells in blastocysts, pregnancy efficiency, delivery rate and cumulative pregnancy efficiency were analyzed. IVF-fertilized embryos exhibited higher blastocyst development competence and embryo quality compared with ICSI embryos. The pregnancy and delivery efficiency was not identified to be significantly different between the two SET models, but it was lower in these two models than in the MET model. The cumulative pregnancy efficiency in SET models, calculated using a mathematical equation, was not decreased. In conclusion, embryo quality was shown to be the primary factor in selecting embryos prior to embryo transfer using sibling oocytes. In addition, single blastocyst transfer can be performed in sibling oocytes without compromising cumulative pregnancy rates, independent of the fertilization approach.

Influence of post-thaw culture on the developmental potential of human frozen embryos

PURPOSE

Apart from freezing/thawing related cryodamage, several additional factors have been identified as major players in the reduction of success rates after frozen embryo transfers. The post-thaw culture is particularly relevant as it may amplify environmental influences over a stressed embryo. In the present study the influence of the post-thaw culture duration on the implantation and developmental potential of cleavage stage embryos was evaluated.

METHODS

In this retrospective evaluation, that spanned an 8-year period, 631 frozen-thawed embryos were allocated to one of two study groups, depending on their post-thaw culture period: 1) the long (18-24 h), or 2) the short (2-5 h) culture group. Groups were compared regarding implantation rate and live birth rate per embryo transferred. This comparison was corrected for the most common confounding factors such as maternal age at oocyte pick-up, number of transferred embryos, developmental day at freezing, blastomere survival after thawing, catheter used for transfer and year of procedure.

RESULTS

Implantation and live birth rate per embryo transferred were inversely related to the duration of the post-thaw culture, as diminishing this period significantly increased both rates. Moreover, no advantage could be found for a long post-thaw culture period, even for embryos with observed mitotic activity.

CONCLUSION

This retrospective analysis indicates that a short post-thaw culture period is associated with higher implantation and live birth rates per embryo. This study supports selection of frozen-thawed embryos strictly based on blastomere cryosurvival and raises the hypothesis that environmental factors may have an important role on embryo implantation and developmental potential during post-thaw culture.

A novel isolator-based system promotes viability of human embryos during laboratory processing

In vitro fertilisation (IVF) and related technologies are arguably the most challenging of all cell culture applications. The starting material is a single cell from which one aims to produce an embryo capable of establishing a pregnancy eventually leading to a live birth. Laboratory processing during IVF treatment requires open manipulations of gametes and embryos, which typically involves exposure to ambient conditions. To reduce the risk of cellular stress, we have developed a totally enclosed system of interlinked isolator-based workstations designed to maintain oocytes and embryos in a physiological environment throughout the IVF process. Comparison of clinical and laboratory data before and after the introduction of the new system revealed that significantly more embryos developed to the blastocyst stage in the enclosed isolator-based system compared with conventional open-fronted laminar flow hoods. Moreover, blastocysts produced in the isolator-based system contained significantly more cells and their development was accelerated. Consistent with this, the introduction of the enclosed system was accompanied by a significant increase in the clinical pregnancy rate and in the proportion of embryos implanting following transfer to the uterus. The data indicate that protection from ambient conditions promotes improved development of human embryos. Importantly, we found that it was entirely feasible to conduct all IVF-related procedures in the isolator-based workstations.

A physiological replacement for polyvinylpyrrolidone (PVP) in assisted reproductive technology

The technique of intracytoplasmic sperm injection (ICSI) requires mechanical immobilization of the sperm that are to be injected; damage thus caused to the sperm membrane is considered to be necessary to activate the sperm for fertilization. Mechanical immobilization and the injection procedure are facilitated by introducing the sperm into a viscous medium that will hinder motility: a solution of polyvinylpyrrolidone (PVP) has been used successfully for this purpose. PVP is an artificial polymer, which has been regarded as chemically inert, although adverse effects have been reported as a result of its use both in vivo and in vitro. Therefore, the use of hyaluronate, the natural component of the extracellular matrix of the cumulus-oocyte complex, was investigated as a replacement for PVP during ICSI. A solution of hyaluronate was found to be as effective as PVP in facilitating the injection procedure, its effect on sperm motility was readily reversible, and its use did not affect the outcome of the treatment cycles in terms of fertilization, pregnancy and live birth rates. Every attempt should be made to eliminate artificial factors in assisted reproductive procedures. Hyaluronate, a natural and readily degradable glycosaminoglycan can be used as a substitute for the artificial PVP polymer without jeopardising the outcome of the treatment cycle.

Sperm nuclear vacuoles, as assessed by motile sperm organellar morphological examination, are mostly of acrosomal origin

Microinjection of nuclear vacuole-free spermatozoa selected by motile sperm organellar morphological examination (MSOME) has been claimed to enhance assisted reproduction treatment outcome compared with intracytoplasmic sperm injection. However, the nature of these nuclear vacuoles is unclear, since their localization at the front of the sperm head suggests they might be of acrosomal origin. To study this hypothesis, acrosomal status was evaluated using Pisum sativum agglutinin staining on a smear, together with sperm organellar morphological examination using the same optics as for MSOME on 30 sperm samples from infertile patients, yielding >3200 spermatozoa. Vacuoles were present in 61% of spermatozoa when acrosomal material or intact acrosomes were observed, versus 29% when spermatozoa were acrosome reacted (P<0.0001). Induction of the acrosomal reaction by ionophore A23587 from 17.4% to 36.1% significantly increased the percentage of vacuole-free spermatozoa from 41.2% to 63.8% (P<0.001). These data suggest that most nuclear vacuoles are of acrosomal origin. Hence, the best spermatozoa selected by MSOME are mostly acrosome-reacted spermatozoa. As microinjection of spermatozoa with a persistent acrosome drastically hampers embryo development in animal models, this suggests that the improvement in pregnancy rates reported following intracytoplasmic injection of morphologically selected sperm might be due to the procedure allowing injection of acrosome-reacted spermatozoa.

Embryo development after intracytoplasmic sperm injection can be predicted by assessment of sperm nuclear chromatin

Purpose

To assess the influence of structural differences in sperm nuclei on embryo development in intracytoplasmic sperm injection (ICSI).

Methods

Semen obtained from forty-four infertile patients who underwent ICSI was examined. In assessing blastocyst development, only those patients who had successfully obtained over five fertilized eggs were included to exclude any oocyte factors (n = 22). Spermatozoa were assessed using excitation fluorescence flow cytometry with acridine orange and the sperm chromatin dispersion (SCD) test.

Results

There was a significant positive correlation between the COMP values obtained from flow cytometry and blastocyst formation. (r = 0.477, p = 0.025). There was a significant negative correlation between the SCD values representing DNA fragmentation and blastocyst formation. (r = 0.796, p < 0.001). COMP values and SCD values were independent parameters to assess sperm nuclear quality regarding embryo development in vitro (r = 0.224, p = 0.080).

Conclusion

Results suggest that injection of spermatozoa with fewer disulfide bonds and less nuclear DNA fragmentation could achieve better blastocyst formation in human ICSI. Assessment of sperm chromatin should help to predict embryo development after ICSI.

Effect of glutathione on the development of rat embryos following microinsemination

Purpose

The present study was carried out to evaluate the role of glutathione on rat embryo developmental potential after ICSI. We observed the effects of glutathione on the development of non-treated rat embryos, ICSI embryos and embryos with sham injection treatment. The development of glutathione-microinjected embryos was also observed.

Methods

Oocytes and fertilized embryos were obtained from superovulated Wistar-Imamichi rats and cultured in mR1ECM medium. Oocytes and embryos were then allowed to develop to assess the effect of glutathione on the development rate in intact embryos, micro-injected embryos and ICSI embryos.

Results

(1) In the intact embryo, the proportion of blastocyst stage development increased when 0.01 mM GSH was added to the medium compared to the control. (2) Microinjection of glutathione (GSSG, GSH) into the embryo increased development at each stage, and the addition of 0.2 nM GSSG or GSH significantly increased blastocyst development, in comparison to that of the control (P < 0.05). (3) Compared to the control, all the GSSG and GSH concentrations improved damaged blastocyst development, where 0.01 mM GSH improved significantly (P < 0.05). (4) The addition of glutathione in the medium increased the rate of blastocyst development after ICSI. A significantly higher number of TE and total cells were obtained in the micro-injected embryo with both of the 0.02 mM GSSG and GSH treatments (P < 0.05).

Conclusions

The addition of glutathione into the culture media can improve early embryo development and is capable of repairing the damage of ICSI rat embryos.

Long-term effects of mouse intracytoplasmic sperm injection with DNA-fragmented sperm on health and behavior of adult offspring

Genetic and environmental factors produce different levels of DNA damage in spermatozoa. Usually, DNA-fragmented spermatozoa (DFS) are used with intracytoplasmic sperm injection (ICSI) treatments in human reproduction, and use of DFS is still a matter of concern. The purpose of the present study was to investigate the long-term consequences on development and behavior of mice generated by ICSI with DFS. Using CD1 and B6D2F1 mouse strains, oocytes were injected with fresh spermatozoa or with frozen-thawed spermatozoa without cryoprotector. This treatment increased the percentage of TUNEL-positive spermatozoa, tail length as measured by comet assay, and loss of telomeres as measured by quantitative PCR. The ICSI-generated embryos were cultured for 24 h in KSOM, and 2-cell embryos were transferred into CD1 females. The DFS reduced both the rate of preimplantation embryo development and number of offspring. Immunofluorescence staining with an antibody against 5-methylcytosine showed a delay of 2 h on the active demethylation of male pronucleus in the embryos produced by ICSI. Moreover, ICSI affected gene transcription and methylation of some epigenetically regulated genes like imprinting, X-linked genes, and retrotransposon genes. At 3 and 12 mo of age, ICSI with DFS-produced animals and in vivo-fertilized controls were submitted to behavioral tests: locomotor activity (open field), exploratory/anxiety behavior (elevated plus maze, open field), and spatial memory (free-choice exploration paradigm in Y maze). Females produced by ICSI showed increased anxiety, lack of habituation pattern, deficit in short-term spatial memory, and age-dependent hypolocomotion in the open-field test (P<0.05). Postnatal weight gain of mice produced by ICSI with fresh or frozen sperm was higher than that of their control counterparts from 16 wk on (P<0.01). Anatomopathological analysis of animals at 16 mo of age showed some large organs and an increase in pathologies (33% of CD1 females produced with DFS presented some solid tumors in lungs and dermis of back or neck). Moreover, 20% of the B6D2F1 mice generated with DFS died during the first 5 mo of life, with 25% of the surviving animals showing premature aging symptoms, and 70% of the B6D2F1 mice generated with DFS died earlier than controls with different kind of tumors. We propose that depending on the level of DFS, oocytes may partially repair fragmented DNA, producing blastocysts able to implant and produce live offspring. The incomplete repair, however, may lead to long-term pathologies. Our data indicate that use of DFS in ICSI can generate effects that only emerge during later life, such as aberrant growth, premature aging, abnormal behavior, and mesenchymal tumors.

Incomplete denudation of oocytes prior to ICSI enhances embryo quality and blastocyst development

BACKGROUND

Granulosa cells are essential mediators of oocyte maturation and fertilization. Because of the denudation of oocytes in preparation for ICSI, any potential positive effect of surplus cumulus cells (CCs) on further development would be unable to exert further effect. In order to evaluate the actual influence of adhering cumulus cells on further preimplantation development, this prospective study was carried out.

METHODS

Sibling cumulus-oocyte complexes for 57 ICSI patients were split into a study group (incomplete denudation, n = 314) and a control group (complete denudation, n = 336). According to the cumulus cell pattern after partial denudation, mature gametes from the study group were further subdivided into type A oocytes, which showed several prominent CC clusters (n = 202), and type B (n = 75), which showed a more homogeneous pattern with CC covering the whole surface of the gamete.

RESULTS

In immature oocytes, presence of adhered CCs led to a significant increase in resumption of meiosis (P < 0.01). Fertilization rate (P < 0.05) and ability to cleave (P < 0.01) was impaired in the study group, because of difficulties in ICSI of type B oocytes. By contrast, embryo morphology on days 2 (P < 0.01) and 3 (P < 0.05), as well as blastocyst formation, was better (P < 0.05) in the study group (55 blastocysts out of 88 zygotes) as compared to that in the control group (49/105).

CONCLUSION

These data indicate that co-culture of oocytes with attached CCs may enhance preimplantation development.

Use of laser-assisted intracytoplasmic sperm injection (ICSI) in patients with a history of poor ICSI outcome and limited metaphase II oocytes

In this study, laser-assisted intracytoplasmic sperm injection (ICSI) improved the fertilization rate and the embryo quality in patients with a history of poor ICSI outcome and with limited metaphase II oocytes. This technique is less traumatic to the oocytes during the procedure, and the use of the technique may be expanded.

A prospective randomized trial of conventional in vitro fertilization versus intracytoplasmic sperm injection in unexplained infertility

PURPOSE

To compare outcomes in patients with unexplained infertility undergoing conventional in vitro fertilization (IVF) versus intracytoplasmic sperm injection (ICSI).

METHODS

Sixty women with unexplained infertility in a Canadian tertiary-level clinic were randomized to IVF or ICSI. Subjects underwent downregulation with gonadotropin-releasing hormone agonist prior to initiation of recombinant human follicle-stimulating hormone. The primary outcome measure was fertilization rate. Secondary outcomes included implantation rate, embryo quality, clinical pregnancy rate, and live birth rate.

RESULTS

There was no statistically significant difference in fertilization rate (77.2% IVF vs. 82.4% ICSI), implantation rate (38.2% IVF vs. 44.4% ICSI), clinical pregnancy rate (50% in each group), or live birth rate (46.7% IVF vs. 50% ICSI). There were two cases of failed fertilization in the IVF group. There was no significant difference in embryo quality between groups.

CONCLUSIONS

There were no differences in clinical outcomes associated with IVF versus ICSI in the treatment of unexplained infertility.

Can dissenting findings regarding the comparative effectiveness of ICSI and IVF be explained by a learning curve?

PURPOSE

To determine whether between-trial heterogeneity in relative risk of fertilisation for intracytoplasmic sperm injection (ICSI) compared to in vitro fertilisation (IVF) can be explained by learning or by between-trial variation in patient characteristics.

METHODS

Systematic review and meta-analysis of trials comparing fertilisation outcomes for ICSI and IVF (without surgical sperm retrieval). Meta-regressions to identify associations between treatment effect and trial characteristics.

RESULTS

Coefficients on individually significant covariates from the meta-regressions confirm that the ICSI versus IVF treatment effect is increased when patients are "unsuited for IVF" but reduced as semen quality improves and when IVF insemination concentrations are increased. However, the relative risk of fertilisation varies inversely with publication date; contrary to the hypothesised learning effect.

CONCLUSION

While it is recognised that publication date might proxy for unobserved covariates, the possibility of a learning effect in favour of ICSI is not supported by the meta-regression.

Precycle administration of GnRH antagonist and microdose HCG decreases clinical pregnancy rates without affecting embryo quality and blastulation

The outcome of a novel protocol utilizing precycle gonadotrophin-releasing hormone (GnRH) antagonist administration and LH activity support with microdose recombinant human chorionic gonadotrophin (HCG) was compared to GnRH agonist long protocol used in patients undergoing their first ICSI (n=707) or IVF (n=571) cycles, which had resulted in one or two blastocyst transfers. In GnRH antagonist cycles, cetrorelix acetate (3 mg) was administered s.c. 4 days before FSH stimulation and a repeat dose was given when the lead follicular diameter was 13-14 mm. LH support was provided by recombinant HCG (2.5 microg). Embryo progression and blastulation were evaluated using embryo progression indices and blastocyst quality scores. The tested protocol demonstrated reduced implantation and clinical pregnancy rates as compared with GnRH agonist long protocol, although the embryo progression and blastulation parameters and blastocyst quality were comparable among the groups. Logistic regression models further supported the significant negative impact of GnRH antagonist/microdose HCG protocol on clinical pregnancy rates in both ICSI and IVF patients. Assisted reproduction cycles with fresh blastocyst transfers utilizing precycle GnRH antagonist administration and microdose HCG support resulted in lower implantation and clinical pregnancy rates as compared with GnRH agonist cycles, although the embryo progression and blastulation parameters were comparable.

Blastocyst formation in in vitro fertilization versus intracytoplasmic sperm injection cycles: influence of the fertilization procedure

OBJECTIVE

To compare the quality of early cleaving embryos and blastocysts obtained by IVF or intracytoplasmic sperm injection (ICSI).

DESIGN

Retrospective study.

SETTING

Tertiary infertility center.

PATIENT(S)

Sibling oocytes of 104 patients in 104 IVF vs. ICSI cycles.

INTERVENTION(S)

Cumulus oocyte complexes (n = 1,358) were randomly subjected to ICSI or IVF.

MAIN OUTCOME MEASURE(S)

Embryo development and blastocyst formation rate. The blastocyst quality and cycle efficiency were also evaluated.

RESULT(S)

Early embryo cleavage was higher after ICSI (37.1%) compared to IVF (14.1%). The percentage of > or =4-cell embryos on day 2 and > or =8-cell embryos on day 3 was similar for both procedures. The overall blastocyst formation was not different between ICSI (50.2%) and IVF (54.8%), neither was the percentage of good-quality blastocysts (31.3% for ICSI and 36.0% for IVF). The total cycle efficiency (percentage of embryos transferred and frozen per two pronuclei [2PN]) was comparable for the two techniques (51.7% for ICSI and 57.4% for IVF).

CONCLUSION(S)

No differences were found on sibling oocytes in the embryo development and blastocyst formation, irrespective of the fertilization procedure. Earlier suggestions that the ICSI technique may result in impaired blastocyst development were not confirmed in this study.

Surface morphology of the zona pellucida surrounding human blastocysts obtained after in vitro fertilization

Human zona pellucida (ZP) is maintained up to the blastocyst stage prior to hatching. In in vitro fertilized (IVF) embryos, it eventually acts as a morphodynamic interface between the cultured embryo and its microenvironment. Ultrastructural data on the ZP of IVF blastocysts are scarce in humans. We employed correlated phase contrast microscopy (PCM) and scanning electron microscopy (SEM) to study retrospectively the ultrastructural morphology of the ZP outer surface of 20 IVF human blastocysts from 16 Japanese patients (28-44 years of age, average 36.7+/-4.2) with a history of infertility. Blastocysts were derived from conventional in vitro fertilization (cIVF) (n = 10) and from intracytoplasmic sperm injection (ICSI) (n = 10). Both cIVF and ICSI groups included "clear blastocysts" (n = 5) and "dark blastocysts" (n = 5). By PCM, the clear blastocysts exhibited a regular, round-shaped contour and consisted of clear and voluminous cells. By SEM, they displayed a spongy ZP with numerous fenestrations formed by networked filaments. By PCM, dark blastocysts appeared irregularly shaped and often collapsed, and comprised dark cells and debris. By SEM, their ZP were smooth with remnants of compact fenestrations. In conclusion, viable blastocysts presented a normal ZP outer surface ultrastructure, whereas unhealthy blastocysts showed an altered ZP outer surface, comparable to that of immature/atretic oocytes. Such alterations could reflect sub-optimal culture conditions and/or could be related to blastocyst degenerative processes. The blastocyst ZP surface ultrastructure was unaffected by the fertilization technique (cIVF or ICSI). These data suggest that blastocyst survival in vitro is related to ZP ultrastructure maintenance.

World Health Organization grade 'a' motility and zona-binding test accurately predict IVF outcome for mild male factor and unexplained infertilities

BACKGROUND

The aim of this study was to determine the pronostic value of a sperm-zona pellucida (ZP) binding assay, combined with World Health Organization (WHO) grade 'a' sperm motility on the day of the IVF attempt, to predict sperm fertilizing ability in unexplained and moderate male factor infertilities.

METHODS

In total, 84 couples (64 unexplained infertility; 20 male factor) underwent both a sperm-ZP binding assay and an IVF attempt, irrespective of the test's result. The test was negative when grade 'a' motility was #5% and/or the ZP binding index was <0.7. Fertilization and pregnancy rates were related to the test's results.

RESULTS

Thirty-one patients had a negative test (group N) and 53 a positive test (group P). A difference was observed concerning the fertilization rate [median (range): 0 (0-75%) versus 50 (0-100%); P = 0.0001] and the number of cycles with fertilization rate <20% (65 versus 23%; P = 0.0002) between groups N and P respectively. In the group of unexplained and male factor infertilities, the test showed a sensitivity of 83 and 60%, specificity of 50 and 90%, positive predictive value of 76 and 86%, and negative predictive value of 61 and 69% respectively.

CONCLUSION

Sperm-ZP binding test, combined with WHO grade 'a' motility assessment, is relevant to prevent IVF fertilization failures in unexplained infertility and, most particularly, in moderate male factor infertility.

Should ICSI be used in non-male factor infertility?

There is general agreement that intracytoplasmic sperm injection (ICSI) should be used in male factor infertility cases, such as oligoasthenoteratozoospermia, presence of anti-sperm antibodies, or azoospermia, these cases being diagnosed through abnormal semen analysis. There are no randomized clinical trials comparing ICSI with IVF (or other interventions) where semen quality is so poor that IVF would not achieve fertilization. It is accepted that ICSI is the only treatment option in those circumstances. The role of ICSI where IVF can be expected to give a reasonable fertilization rate is the question that needs to be answered. The argument is whether or not ICSI should be used for all cases of infertility. This paper proposes and strongly supports the use of ICSI for all indications. Considerations of fertilization and embryo development, cost effectiveness and safety will be clearly discussed.

Growth rate of human preimplantation embryos is sex dependent after ICSI but not after IVF

BACKGROUND

There is concern that IVF and/or ICSI might have an adverse effect on embryonic development via epigenetic alterations. Such alterations might also be involved in the sex-related growth differences in preimplantation embryos found in some animal species. In the present study we analysed cell numbers of human male and female surplus embryos that developed to the blastocyst stage after either IVF or ICSI in order to investigate possible sex-dependent differential growth rates.

METHODS

Blastocysts resulting from surplus embryos obtained after either IVF or ICSI during a 5 year study period were analysed using fluorescence in situ hybridization (FISH).

RESULTS

The number of cells and sex could be determined in 330 blastocysts collected from 92 IVF cycles and in 322 blastocysts collected from 121 ICSI cycles. Whereas female and male embryos originating from IVF showed comparable mean log cell numbers per embryo +/- SEM (3.76+/-0.05 in 147 female and 3.72+/-0.04 in 183 male embryos), significant differences were observed in embryos originating from ICSI (3.57+/-0.05 in 162 female and 3.90+/-0.03 in 160 male embryos). The sex-related growth difference was significantly greater in ICSI than in IVF embryos. In a subset of 84 embryos, inner cell mass (ICM) and trophectoderm (TE) were analysed separately. A significantly higher mean log cell number of TE cells in ICSI male embryos was found as compared to their female counterparts (3.44+/-0.12 in 16 female and 3.90+/-0.11 in 29 male embryos), whereas this difference was not found in IVF embryos.

CONCLUSION

A clear sex-related growth difference was found in human blastocysts originating from ICSI, but not in blastocysts originating from IVF. It is as yet unknown which mechanism is responsible for our findings. We hypothesize that the ICSI procedure might interfere with the process of imprinted X-inactivation.

Conventional in vitro fertilization versus intracytoplasmic sperm injection for sibling oocytes in couples with mild oligoteratoasthenozoospermia and couples with normal sperm

Use of intracytoplasmic sperm injection (ICSI) in couples with mild oligoteratoasthenozoospermia decreases the complete fertilization failure rate and may also reduce the embryo cleavage rate. ICSI does not benefit couples with normal sperm.

Predictive value of the number of oocytes retrieved at ultrasound-directed follicular aspiration with regard to fertilization rates and pregnancy outcome in intracytoplasmic sperm injection treatment cycles

OBJECTIVE

To determine the number of oocytes sufficient for satisfactory fertilization and pregnancy rates in intracytoplasmic sperm injection cycles.

DESIGN

A retrospective analysis.

SETTING

A private assisted conception unit.

PATIENT(S)

Women in whom at least one oocyte was retrieved in consecutive ultrasound-directed follicular aspirations between June 1999 and June 2001.

INTERVENTION(S)

Standard protocol for pituitary down-regulation and ovarian stimulation.

MAIN OUTCOME MEASURE(S)

Number of oocytes retrieved, embryos transferred, fertilization, and pregnancy rates.

RESULT(S)

The numbers of oocytes obtained per cycle were classified into groups A, B, C, and D, consisting of 110, 124, 96, and 122 cycles, with 1-5, 6-10, 11-15, >15 oocytes retrieved from each patient in each group, respectively. The chance of not obtaining a viable oocyte for injection was highest in group A (5.5%). Most fertilization failures occurred in group A (11.8%). Total cleavage failure occurred in the greatest percentage of cycles in group A (3.6%) with a significantly lower mean number of embryos (1.9 +/- 1.7) being transferred. The clinical pregnancy rate was also lowest in group A (7.1%) compared with groups B (25.8%), C (20.8%), and D (23.8%).

CONCLUSION(S)

Retrieval of between 6 and 10 oocytes per patient and transfer of a maximum of three cleavage-stage embryos results in high pregnancy rates.

Overnight incubation improves selection of frozen–thawed blastocysts for transfer: preliminary study using supernumerary embryos

A study was undertaken to determine whether the interval between thawing and transfer influences both biological and clinical outcomes of cryopreserved blastocysts, using supernumerary embryos cultured in sequential media. One hundred and seventy-two patients who underwent blastocyst thawing without any exclusion criteria were included in this single center prospective study of blastocyst thawing cycles. Outcome of 338 blastocysts originating from culture of supernumerary embryos in sequential media was analyzed after 4 or 20 h of culture between thawing and transfer. Survival rate, re-expansion and hatching rates for surviving blastocysts, implantation rates (IRs), pregnancy and miscarriage rates were studied. Blastocyst survival was not influenced by the incubation time after thawing; however both re-expansion and hatching rates were increased after 20-h incubation. Moreover, the IR per thawed or transferred blastocyst was increased three-fold after 20-h incubation compared to 4-h incubation. Increasing the interval between thawing and transfer appears to be beneficial in order to better select for transfer frozen-thawed blastocysts.

Male infertility

Infertility affects 13-18% of couples and growing evidence from clinical and epidemiological studies suggests an increasing incidence of male reproductive problems. The pathogenesis of male infertility can be reflected by defective spermatogenesis due to pituitary disorders, testicular cancer, germ cell aplasia, varicocele and environmental factors or to defective sperm transport due to congenital abnormalities or immunological and neurogenic factors. Recent studies suggest an increased incidence of genetic disorders related to male infertility which may affect different levels, interfering with germ cell generation and maturation or leading to the production of non-functional spermatozoa. The identification of genetic causes of male infertility raises the issue of the transmission of defects to the offspring, a situation that is becoming more important given the increasing use of intracytoplasmic sperm injection (ICSI), a procedure in which the natural selection of the spermatozoa is by-passed. Fertilization can occur in vitro using ejaculated, epididymal or testicular spermatozoa, either fresh or frozen-thawed, providing opportunities hitherto not possible for men to be genetic fathers.

Effect of ICSI on subsequent blastocyst development and pregnancy rates

PURPOSE

To investigate whether ICSI (intracytoplasmic sperm injection) results in decreased blastocyst formation and pregnancy compared to IVF (in vitro fertilization).

METHODS

We performed a retrospective analysis of blastocyst transfer (BT) offered routinely to patients under age 40 with > or = three 8-cell embryos on day 3 and compared IVF to ICSI cycles. Sequential media were used with P1 until day 3, then Blastocyst Medium until day 5/6.

RESULTS

There were 131 IVF and 75 ICSI cycles. There was no difference in age, number of oocytes, zygotes, 8-cell embryos, blastocysts on days 5 and 6, or embryos transferred. Progression to blastocyst was similar (78% for IVF and 73% for ICSI) as was the viable pregnancy rate (51.4% for IVF and 55% for ICSI). No cycles failed to form blastocysts.

CONCLUSIONS

The progression to blastocyst and the likelihood of conceiving a viable pregnancy were unaltered by ICSI. Thus it seems appropriate for programs to offer BT to patients undergoing ICSI using the same inclusion criteria applied to their IVF patients.

Analysis of intracytoplasmic sperm injection procedures related to delayed insemination and ejaculated, epididymal and testicular spermatozoa

In all, 1210 treatment cycles were divided into three categories for retrospective analysis according to the period of delay between oocyte retrieval (occurring at a fixed time after human chorionic gonadotrophin) and intracytoplasmic sperm injection (ICSI) of <3 h, 3-5 h, >5 h (referred to as 'delayed ICSI'). Three stages from oocyte to the birth of a live baby were identified for statistical analysis, (i) fertilization (2PN zygotes), (ii) cleavage of 2PN zygotes, (iii) transferred embryo to live birth. Stages 1, 2 and 3 were analysed statistically for the three time periods. Chi-square analysis showed no significant effect of delayed ICSI on fertilization (chi(2) = 3.615, P = 0.65), and embryo transfer to birth (chi(2) = 1.840, P = 0.399). The effect on cleavage was significant (chi(2) = 9.625, P = 0.008). However, shorter incubation times produced results which were better than the traditional longer ones. The success rate at the cleavage stage was so high that the marginal advantage had very little effect on the overall process. This study of a substantial patient sample establishes that ICSI on a peri-ovulatory oocyte (<3 h after oocyte retrieval) does not compromise outcome parameters, and that longer periods of incubation (>5 h) do not offer a statistically significant advantage.

ICSI and day 5 embryo transfers: higher implantation rates and lower rate of multiple pregnancy with prolonged culture

This retrospective review study, carried out in a private IVF clinic, compared pregnancy and implantation rates with day 3 versus day 5 embryo transfers in a selected group of patients. Participants were patients who failed to achieve pregnancy in at least one previous attempt with embryo transfer on days 2 or 3, and had more than five oocytes fertilized. A total of 296 patients who had undergone day 3 (group A) transfers were compared with 154 who had undergone day 5 transfers (group B). Interventions were intracytoplasmic sperm injection (ICSI), day 3 and day 5 embryo transfer. Outcome measures were pregnancy, implantation, multiple gestation and blastocyst formation rates. Overall, 86.4% of embryos were at the six- to eight-cell stage at 72 h and 30% developed to blastocyst by day 5. The mean number of embryos transferred was 4.0 on day 3 and 3.0 on day 5. Pregnancy and implantation rates were 34.8 and 11.5% in group A, versus 45.3 and 18.5% in group B. Multiple gestation rate was 47.1% in group A and 28.5% in group B. Prolonging embryo culture in vitro to day 5 improved embryo selection and implantation rates. A significant decrease in high order gestations was achieved by reducing the number of embryos transferred, without compromising the pregnancy rates.

Fertilization rate and preimplantation development after intracytoplasmic sperm injection

Intracytoplasmic sperm injection (ICSI) is the treatment of choice in cases of male factor infertility. In the present review, all data from the literature regarding early fertlilization and preimplantation embryo development are analysed. ICSI seems to offer better fertilization rates than conventional IVF, even in the absence of a male factor and in prospective, randomized studies on sibling oocytes. Blastocyst formation is lower in ICSI than in IVF. This may be due to sublethal disturbances in oocyte architecture and function. Implantation and pregnancy rates, however, are similiar in ICSI and conventional IVF. Therefore, it can be concluded that ICSI offers a safe approach, as far as is known to date, for the treatment of male factor infertility. Embryo selection in cases of sublethal damage to oocytes seems to take place in the early preimplantation stages. Nor does the risk of monozygotic twinning, which was also proposed to be higher in ICSI compared with conventional IVF, seem to increase with this procedure.

Micromanipulation of the human oocyte

Intracytoplasmic sperm injection (ICSI) provides an excellent outcome in a consistent manner, and is therefore used worldwide as a routine procedure. Since its introduction, few modifications have been made to its methodology. Recently, a combination of ICSI with micro-hole drilling by laser (LA-ICSI) of the zona pellucida appeared to decrease oocyte degeneration rates and to improve embryo quality and implantation. Cytoplasmic transfer is a more recently introduced procedure where the objective is to improve the quality of patients' oocytes by transferring cytoplasm from a good quality donor oocyte, in cases where it is assumed that cytoplasm is compromised. Nuclear transfer, involving exchange of nuclei between donor and receptor oocytes, is still an experimental procedure, the objective being similar to cytoplasmic transfer in improving oocyte/embryo quality. A nuclear transfer procedure involving somatic cells for reproductive purposes should not be used in humans, for ethical and technical considerations. On the other hand, nuclear transfer for therapeutic purposes to obtain stem cells may be considered in respect of its unique potential in medicine. Finally, the most recently emerged new concept under investigation is the haploidization of somatic cells for the purpose of creating artificial gametes.