Embryo selection: the role of time-lapse monitoring

The mammalian sperm factor phospholipase C zeta is critical for early embryo division and pregnancy in humans and mice

STUDY QUESTION

Are sperm phospholipase C zeta (PLCζ) profiles linked to the quality of embryogenesis and pregnancy?

SUMMARY ANSWER

Sperm PLCζ levels in both mouse and humans correlate with measures of ideal embryogenesis whereby minimal levels seem to be required to result in successful pregnancy.

WHAT IS KNOWN ALREADY

While causative factors underlying male infertility are multivariable, cases are increasingly associated with the efficacy of oocyte activation, which in mammals occurs in response to specific profiles of calcium (Ca2+) oscillations driven by sperm-specific PLCζ. Although sperm PLCζ abrogation is extensively linked with human male infertility where oocyte activation is deficient, less is clear as to whether sperm PLCζ levels or localization underlies cases of defective embryogenesis and failed pregnancy following fertility treatment.

STUDY DESIGN, SIZE, DURATION

A cohort of 54 couples undergoing fertility treatment were recruited at the assisted reproductive technology laboratory at the King Faisal Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia. The recruitment criteria for males was a minimum sperm concentration of 5×106 sperm/ml, while all female patients had to have at least five oocytes. Sperm PLCζ analysis was performed in research laboratories, while semen assessments were performed, and time-lapse morphokinetic data were obtained, in the fertility clinic as part of routine treatment. The CRISPR/Cas9 system was concurrently used to induce indels and single-nucleotide mutations within the Plcζ gene to generate strains of Plcζ mutant mice. Sperm PLCζ was evaluated using immunofluorescence and immunoblotting with an antibody of confirmed consistent specificity against PLCζ.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We evaluated PLCζ profiles in sperm samples from 54 human couples undergoing fertility treatment in the context of time-lapse morphokinetic analysis of resultant embryos, correlating such profiles to pregnancy status. Concurrently, we generated two strains of mutant Plcζ mice using CRISPR/Cas9, and performed IVF with wild type (WT) oocytes and using WT or mutant Plcζ sperm to generate embryos. We also assessed PLCζ status in WT and mutant mice sperm in the context of time-lapse morphokinetic analysis and breeding outcomes.

MAIN RESULTS AND THE ROLE OF CHANCE

A significant (P ≤ 0.05) positive relationship was observed between both PLCζ relative fluorescence and relative density with the times taken for both the second cell division (CC2) (r = 0.26 and r = 0.43, respectively) and the third cell division (S2) (r = 0.26). Examination of localization patterns also indicated significant correlations between the presence or absence of sperm PLCζ and CC2 (r = 0.27 and r = -0.27, respectively; P ≤ 0.025). Human sperm PLCζ levels were at their highest in the ideal times of CC2 (8-12 h) compared to time ranges outside the ideal timeframe (<8 and >12 h) where levels of human sperm PLCζ were lower. Following assignment of PLCζ level thresholds, quantification revealed a significantly higher (P ≤ 0.05) rate of successful pregnancy in values larger than the assigned cut-off for both relative fluorescence (19% vs 40%, respectively) and relative density (8% vs 54%, respectively). Immunoblotting indicated a single band for PLCζ at 74 kDa in sperm from WT mice, while a single band was also observed in sperm from heterozygous of Plcζ mutant mouse sperm, but at a diminished intensity. Immunofluorescent analysis indicated the previously reported (Kashir et al., 2021) fluorescence patterns in WT sperm, while sperm from Plcζ mutant mice exhibited a significantly diminished and dispersed pattern at the acrosomal region of the sperm head. Breeding experiments indicated a significantly reduced litter size of mutant Plcζ male mice compared to WT mice, while IVF-generated embryos using sperm from mutant Plcζ mice exhibited high rates of polyspermy, and resulted in significantly reduced numbers of these embryos reaching developmental milestones.

LIMITATIONS, REASONS FOR CAUTION

The human population examined was relatively small, and should be expanded to examine a larger multi-centre cohort. Infertility conditions are often multivariable, and it was not possible to evaluate all these in human patients. However, our mutant Plcζ mouse experiments do suggest that PLCζ plays a significant role in early embryo development.

WIDER IMPLICATIONS OF THE FINDINGS

We found that minimal levels of PLCζ within a specific range were required for optimal early embryogenesis, correlating with increased pregnancy. Levels of sperm PLCζ below specific thresholds were associated with ineffective embryogenesis and lower pregnancy rates, despite eliciting successful fertilization in both mice and humans. To our knowledge, this represents the first time that PLCζ levels in sperm have been correlated to prognostic measures of embryogenic efficacy and pregnancy rates in humans. Our data suggest for the first time that the clinical utilization of PLCζ may stand to benefit not just a specific population of male infertility where oocyte activation is completely deficient (wherein PLCζ is completely defective/abrogated), but also perhaps the larger population of couples seeking fertility treatment.

STUDY FUNDING/COMPETING INTEREST(S)

J.K. is supported by a faculty start up grant awarded by Khalifa University (FSU-2023-015). This study was also supported by a Healthcare Research Fellowship Award (HF-14-16) from Health and Care Research Wales (HCRW) to J.K., alongside a National Science, Technology, and Innovation plan (NSTIP) project grant (15-MED4186-20) awarded by the King Abdulaziz City for Science and Technology (KACST) for J.K. and A.M.A. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

WISE: whole-scenario embryo identification using self-supervised learning encoder in IVF

PURPOSE

To study the effectiveness of whole-scenario embryo identification using a self-supervised learning encoder (WISE) in in vitro fertilization (IVF) on time-lapse, cross-device, and cryo-thawed scenarios.

METHODS

WISE was based on the vision transformer (ViT) architecture and masked autoencoders (MAE), a self-supervised learning (SSL) method. To train WISE, we prepared three datasets including the SSL pre-training dataset, the time-lapse identification dataset, and the cross-device identification dataset. To identify whether pairs of images were from the same embryos in different scenarios in the downstream identification tasks, embryo images including time-lapse and microscope images were first pre-processed through object detection, cropping, padding, and resizing, and then fed into WISE to get predictions.

RESULTS

WISE could accurately identify embryos in the three scenarios. The accuracy was 99.89% on the time-lapse identification dataset, and 83.55% on the cross-device identification dataset. Besides, we subdivided a cryo-thawed evaluation set from the cross-device test set to have a better estimation of how WISE performs in the real-world, and it reached an accuracy of 82.22%. There were approximately 10% improvements in cross-device and cryo-thawed identification tasks after the SSL method was applied. Besides, WISE demonstrated improvements in the accuracy of 9.5%, 12%, and 18% over embryologists in the three scenarios.

CONCLUSION

SSL methods can improve embryo identification accuracy even when dealing with cross-device and cryo-thawed paired images. The study is the first to apply SSL in embryo identification, and the results show the promise of WISE for future application in embryo witnessing.

The number of nuclei in compacted embryos, assessed by optical coherence microscopy, is a non-invasive and robust marker of mouse embryo quality

Optical coherence microscopy (OCM) visualizes nuclei in live, unlabeled cells. As most cells are uninucleated, the number of nuclei in embryos may serve as a proxy of the cell number, providing important information on developmental status of the embryo. Importantly, no other non-invasive method currently allows for the cell number count in compacted embryos. We addressed the question of whether OCM, by providing the number of nuclei in compacted mouse embryos, may help evaluate embryo quality. We subjected compacted embryonic Day 3 (E3.0: 72 h after onset of insemination) mouse embryos to OCM scanning and correlated nuclei number and developmental potential. Implantation was assessed using an outgrowth assay (in vitro model meant to reflect embryonic ability to implant in vivo). Embryos with more cells at E3.0 (>18 cells) were more likely to reach the blastocyst stage by E4.0 and E5.0 (P ≪ 0.001) and initiate hatching by E5.0 (P < 0.05) than those with fewer cells (<12 cells). Moreover, the number of cells at E3.0 strongly correlated with the total number of cells in E4.0 and E5.0 embryos (ρ = 0.71, P ≪ 0.001 and ρ = 0.61, P ≪ 0.001, respectively), also when only E4.0 and E5.0 blastocysts were considered (ρ = 0.58, P ≪ 0.001 and ρ = 0.56, P ≪ 0.001, respectively). Additionally, we observed a strong correlation between the number of cells at E3.0 and the number of trophectoderm cells in E4.0 and E5.0 blastocysts (ρ = 0.59, P ≪ 0.001 and ρ = 0.57, P ≪ 0.001, respectively). Importantly, embryos that had more cells at E3.0 (>18 cells) were also more likely to implant in vitro than their counterparts with fewer cells (<12 cells; P ≪ 0.001). Finally, we tested the safety of OCM imaging, demonstrating that OCM scanning affected neither the amount of reactive oxygen species nor mitochondrial activity in the embryos. OCM also did not hinder their preimplantation development, ability to implant in vitro, or to develop to term after transfer to recipient females. Our data indicate that OCM imaging provides important information on embryo quality. As the method seems to be safe for embryos, it could be a valuable addition to the current repertoire of embryo evaluation methods. However, our study was conducted only on mouse embryos, so the proposed protocol would require optimization in order to be applied in other species.

Use of artificial intelligence embryo selection based on static images to predict first-trimester pregnancy loss

RESEARCH QUESTION

Can an artificial intelligence embryo selection assistant predict the incidence of first-trimester spontaneous abortion using static images of IVF embryos?

DESIGN

In a blind, retrospective study, a cohort of 172 blastocysts from IVF cases with single embryo transfer and a positive biochemical pregnancy test was ranked retrospectively by the artificial intelligence morphometric algorithm ERICA. Making use of static embryo images from a light microscope, each blastocyst was assigned to one of four possible groups (optimal, good, fair or poor), and linear regression was used to correlate the results with the presence or absence of a normal fetal heart beat as an indicator of ongoing pregnancy or spontaneous abortion, respectively. Additional analyses included modelling for recipient age and chromosomal status established by preimplantation genetic testing for aneuploidy (PGT-A).

RESULTS

Embryos classified as optimal/good had a lower incidence of spontaneous abortion (16.1%) compared with embryos classified as fair/poor (25%; OR = 0.46, P = 0.005). The incidence of spontaneous abortion in chromosomally normal embryos (determined by PGT-A) was 13.3% for optimal/good embryos and 20.0% for fair/poor embryos, although the difference was not significant (P = 0.531). There was a significant association between embryo rank and recipient age (P = 0.018), in that the incidence of spontaneous abortion was unexpectedly lower in older recipients (21.3% for age ≤35 years, 17.9% for age 36-38 years, 16.4% for age ≥39 years; OR = 0.354, P = 0.0181). Overall, these results support correlation between risk of spontaneous abortion and embryo rank as determined by artificial intelligence; classification accuracy was calculated to be 67.4%.

CONCLUSIONS

This preliminary study suggests that artificial intelligence (ERICA), which was designed as a ranking system to assist with embryo transfer decisions and ploidy prediction, may also be useful to provide information for couples on the risk of spontaneous abortion. Future work will include a larger sample size and karyotyping of miscarried pregnancy tissue.

No major differences in perinatal and maternal outcomes between uninterrupted embryo culture in time-lapse system and conventional embryo culture

STUDY QUESTION

Is embryo culture in a closed time-lapse system associated with any differences in perinatal and maternal outcomes in comparison to conventional culture and spontaneous conception?

SUMMARY ANSWER

There were no significant differences between time-lapse and conventional embryo culture in preterm birth (PTB, <37 weeks), low birth weight (LBW, >2500 g) and hypertensive disorders of pregnancy for singleton deliveries, the primary outcomes of this study.

WHAT IS KNOWN ALREADY

Evidence from prospective trials evaluating the safety of time-lapse incubation for clinical use show similar embryo development rates, implantation rates, and ongoing pregnancy and live birth rates when compared to conventional incubation. Few studies have investigated if uninterrupted culture can alter risks of adverse perinatal outcomes presently associated with IVF when compared to conventional culture and spontaneous conceptions.

STUDY DESIGN, SIZE, DURATION

This study is a Swedish population-based retrospective registry study, including 7379 singleton deliveries after fresh embryo transfer between 2013 and 2018 from selected IVF clinics. Perinatal outcomes of singletons born from time-lapse-cultured embryos were compared to singletons from embryos cultured in conventional incubators and 71 300 singletons from spontaneous conceptions. Main perinatal outcomes included PTB and LBW. Main maternal outcomes included hypertensive disorders of pregnancy (pregnancy hypertension and preeclampsia).

PARTICIPANTS/MATERIALS, SETTING, METHODS

From nine IVF clinics, 2683 singletons born after fresh embryo transfer in a time-lapse system were compared to 4696 singletons born after culture in a conventional incubator and 71 300 singletons born after spontaneous conception matched for year of birth, parity, and maternal age. Patient and treatment characteristics from IVF deliveries were cross-linked with the Swedish Medical Birth Register, Register of Birth Defects, National Patient Register and Statistics Sweden. Children born after sperm and oocyte donation cycles and after Preimplantation Genetic testing cycles were excluded. Odds ratio (OR) and adjusted OR were calculated, adjusting for relevant confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

In the adjusted analyses, no significant differences were found for risk of PTB (adjusted OR 1.11, 95% CI 0.87-1.41) and LBW (adjusted OR 0.86, 95% CI 0.66-1.14) or hypertensive disorders of pregnancy; preeclampsia and hypertension (adjusted OR 0.99, 95% CI 0.67-1.45 and adjusted OR 0.98, 95% CI 0.62-1.53, respectively) between time-lapse and conventional incubation systems. A significantly increased risk of PTB (adjusted OR 1.31, 95% CI 1.08-1.60) and LBW (adjusted OR 1.36, 95% CI 1.08-1.72) was found for singletons born after time-lapse incubation compared to singletons born after spontaneous conceptions. In addition, a lower risk for pregnancy hypertension (adjusted OR 0.72 95% CI 0.53-0.99) but no significant difference for preeclampsia (adjusted OR 0.87, 95% CI 0.68-1.12) was found compared to spontaneous conceptions. Subgroup analyses showed that some risks were related to the day of embryo transfer, with more adverse outcomes after blastocyst transfer in comparison to cleavage stage transfer.

LIMITATIONS, REASONS FOR CAUTION

This study is retrospective in design and different clinical strategies may have been used to select specific patient groups for time-lapse versus conventional incubation. The number of patients is limited and larger datasets are required to obtain more precise estimates and adjust for possible effect of additional embryo culture variables.

WIDER IMPLICATIONS OF THE FINDINGS

Embryo culture in time-lapse systems is not associated with major differences in perinatal and maternal outcomes, compared to conventional embryo culture, suggesting that this technology is an acceptable alternative for embryo incubation.

STUDY FUNDING/COMPETING INTEREST(S)

The study was financed by a research grant from Gedeon Richter. There are no conflicts of interest for all authors to declare.

TRIAL REGISTRATION NUMBER

N/A.

A comparison of the morphokinetic profiles of embryos developed from vitrified versus fresh oocytes

RESEARCH QUESTION

Do morphokinetic profiles and treatment outcomes differ between embryos developed from vitrified or fresh oocytes?

DESIGN

Retrospective multicentre analysis using data from eight CARE Fertility clinics across the UK between 2012 and 2019. Patients receiving treatment using embryos developed from vitrified oocytes (n = 118 women, n = 748 oocytes), providing 557 zygotes during this time period, were recruited and matched with patients undergoing treatment with embryos developed from fresh oocytes (n = 123 women, n = 1110 oocytes), providing 539 zygotes in the same time frame. Time-lapse microscopy was used to assess morphokinetic profiles, including early cleavage divisions (2- through to 8-cell), post-cleavage stages including time to start of compaction, time to morula, time to start of blastulation and time to full blastocyst. Duration of key stages such as the compaction stage were also calculated. Treatment outcomes were compared between the two groups (live birth rate, clinical pregnancy rate and implantation rate).

RESULTS

A significant delay of 2-3 h across all early cleavage divisions (2- through to 8-cell) and time to start of compaction occurred in the vitrified group versus fresh controls (all P ≤ 0.01). The compaction stage was significantly shorter in vitrified oocytes (19.02 ± 0.5 h) compared with fresh controls (22.45 ± 0.6 h, P < 0.001). There was no difference in the time that fresh and vitrified embryos reached the blastocyst stage (108.03 ± 0.7 versus 107.78 ± 0.6 h). There was no significant difference in treatment outcomes between the two groups.

CONCLUSION

Vitrification is a useful technique for extending female fertility with no effects on IVF treatment outcome.

Previous infection with SARS-CoV-2 impacts embryo morphokinetics but not clinical outcomes in a time-lapse imaging system

The goal for the present study was to investigate whether previous infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may compromise embryo morphokinetics and implantation. For that, a historical cohort study was performed in a private university-affiliated in vitro fertilization center. The study included 1628 embryos from 88 patients undergoing intracytoplasmic sperm injection (ICSI) cycles. Patients were age-matched in a 1:3 ratio to either a coronavirus disease (COVID) group, including patients with a positive SARS-CoV-2 immunoglobulin test (n = 22 patients, 386 embryos), or a control group, including patients with a negative SARS-CoV-2 immunoglobulin test (n = 66, 1242 embryos). The effect of previous infection with SARS-CoV-2 on morphokinetic events and ICSI outcomes was evaluated. Embryos derived from patients in the COVID group presented longer time to pronuclei appearance and fading, time to form two, three, four and five cells, and time to blastulation. The durations of the third cell cycle and to time to complete synchronous divisions were also significantly increased in the COVID group compared with the control group, whereas known implantation diagnosis score Day 5 ranked significantly lower in the COVID group. No differences were observed between the COVID and control groups on clinical outcomes. In conclusion, patients planning parenthood, who have recovered from COVID-19 infection, must be aware of a possible effect of the infection on embryo development potential.

The effect of discrete wavelengths of visible light on the developing murine embryo

PURPOSE

A current focus of the IVF field is non-invasive imaging of the embryo to quantify developmental potential. Such approaches use varying wavelengths to gain maximum biological information. The impact of irradiating the developing embryo with discrete wavelengths of light is not fully understood. Here, we assess the impact of a range of wavelengths on the developing embryo.

METHODS

Murine preimplantation embryos were exposed daily to wavelengths within the blue, green, yellow, and red spectral bands and compared to an unexposed control group. Development to blastocyst, DNA damage, and cell number/allocation to blastocyst cell lineages were assessed. For the longer wavelengths (yellow and red), pregnancy/fetal outcomes and the abundance of intracellular lipid were investigated.

RESULTS

Significantly fewer embryos developed to the blastocyst stage when exposed to the yellow wavelength. Elevated DNA damage was observed within embryos exposed to blue, green, or red wavelengths. There was no effect on blastocyst cell number/lineage allocation for all wavelengths except red, where there was a significant decrease in total cell number. Pregnancy rate was significantly reduced when embryos were irradiated with the red wavelength. Weight at weaning was significantly higher when embryos were exposed to yellow or red wavelengths. Lipid abundance was significantly elevated following exposure to the yellow wavelength.

CONCLUSION

Our results demonstrate that the impact of light is wavelength-specific, with longer wavelengths also impacting the embryo. We also show that effects are energy-dependent. This data shows that damage is multifaceted and developmental rate alone may not fully reflect the impact of light exposure.

Division Behaviors and Their Effects on Preimplantation Development of Pig Embryos

Quality of preimplantation embryos could affect development efficiency after embryo transfer. However, assessment of preimplantation embryos was unsatisfied especially in pig embryos to date. Therefore, the present study was design to investigate available and applicable parameters which indicating development potential and quality of porcine preimplantation embryos produced by handmade cloning (HMC), parthenogenetic activation without zona pellucida (PAZF) and with zona pellucida (PAZI). Results firstly detected a common division behavior that formation of uneven division with two unequal size blastomeres (UD 2-cell), especially in HMC embryos, the proportion of UD 2-cell was significantly higher than that of equal size blastomeres (ED 2-cell) with 72.56 ± 4.56 vs. 24.57 ± 1.92. Formation of UD 2-cell might due to spindle migrates along the long axis in 1-cell stage, and the cleavage furrow not formed in the center of cytoplasm. In the two sister blastomeres of UD 2-cell, unevenly distribution of organelles (mitochondria and lipid droplet) was observed with lower proportion in the smaller one (p<0.05). Althoug no difference of blastocyst rate was observed between UD and ED 2-cell embryos, the cell number per blastocyst from UD 2-cell embryos was lower than that from ED 2-cell embryos (44.15 ± 2.05 vs. 51.55 ± 1.83). Besides, because of nonsynchronized division of each blastomeres, another common behavior that three cleavage routes were observed in all of HMC/PAZF/PAZI embryos that T1 (2-cell → 3-cell → 4-cell → ≥ 5-cell → morula → blastocyst), T2 (2-cell → 3-cell → 4-cell → morula → blastocyst), and T3 (2-cell → 3-cell / 4-cell → morula → blastocyst). Therefore, in pig in vitro produced embryos, division behaviors of uneven volume of cytoplasm and nonsynchronized cell cycles were observed at the early embryonic developmental stage, which might be another potential factor to evaluate embryonic development.

Oocyte quality and embryo selection strategies: a review for the embryologists, by the embryologists

With the advance of assisted reproduction techniques, and the trend towards blastocyst culture and single embryo transfer, gamete and embryo assessment have gained greater importance in ART treatment. Embryo quality depends mainly on gamete quality and culture conditions. Oocyte maturity identification is necessary in order to plan fertilization timing. Mature oocytes at the metaphase II stage show a higher fertilization rate compared to immature oocytes. Morphology assessment is a critical yet challenging task that may serve as a good prognostic tool for future development and implantation potential if done effectively. Various grading systems have been suggested to assess embryos at pronuclear, cleavage, and blastocyst stages. By identifying the embryo with the highest implantation potential, it is possible to reduce the number of embryos transferred without compromising the chances of a successful pregnancy. Apart from the conventional morphology assessment, there are several invasive or non-invasive methods for embryo selection such as preimplantation genetic testing, morphokinetics, proteomics, metabolomics, oxygen consumption, and measurement of oxidative stress in culture medium. Morphokinetics is a method based on time-lapse technology and continuous monitoring of embryos. In this review, we aim to describe and compare the most effective and widely used methods for gamete and embryo assessment as well as embryo selection.

Symmetry at the 4-Cell Stage Is Associated with Embryo Aneuploidy

The purpose of this study was to determine if morphometric parameters that can be measured quantitatively using a time-lapse embryo incubator are associated with aneuploidy. Embryos cultured in a time-lapse incubator and assessed with preimplantation genetic testing for aneuploidy (PGT-A) were analyzed retrospectively. Morphokinetic analysis included timing of cell divisions. Quantitative morphometric measurements included the distance between the second and first polar body, zona pellucida thickness at the pronuclear stage and at the 2-cell stage, and blastomere area at the 2- and 4-cell stages. Symmetry at the 2-cell stage was determined by percent difference between blastomeres; symmetry at the 4-cell stage was the percent difference between the smallest and largest blastomeres. Maternal age, blastocyst grade and day of biopsy were recorded. Euploid embryo characteristics were compared to aneuploid embryos. A receiver operating characteristic (ROC) curve was used to evaluate cell symmetry as a predictor of aneuploidy. Embryos (n = 182) from 21 patients (age 22-43; median = 34) were analyzed. Of the 182 embryos, 45% were euploid. Euploid and aneuploid embryos had similar morphokinetics and morphometry across many measures. As expected, age and blastocyst grade were associated with embryo ploidy. It was notable that, additionally, symmetry at the 4-cell stage (27% vs 31%, p = 0.01) was also associated with embryo ploidy. The optimized cutoff from the ROC curve to predict aneuploidy was determined to be 21%. Embryos with > 21% asymmetry at the 4-cell stage had high rates of aneuploidy while morphokinetic parameters were similar. In conclusion, this suggests that embryo selection models using time-lapse parameters would improve if they incorporate cleavage-stage morphometrics.

Cellular Fragments in the Perivitelline Space Are Not a Predictor of Expanded Blastocyst Quality

The presence of cellular fragments in the perivitelline space is a commonly used parameter to determine quality before transfer of in vitro produced (IVP) embryos. However, this parameter is difficult to assess after blastocyst expansion. In this study, we used mechanical hatching to confirm the presence of cellular fragments in the perivitelline space of bovine IVP blastocysts. We further looked for associations between possible apoptosis within extruded cells/ cellular fragments and the quality of bovine blastocysts using quantitative RT-PCR and immunofluorescence. Surprisingly, more than 42% of expanded blastocysts had cellular fragments in the perivitelline space; however, more than 37% of extruded cells were TUNEL negative. We observed no significant difference in embryo quality between expanded blastocysts with and without cellular fragments in the perivitelline space. Overall, our data suggest that embryos extrude abnormal cells to maintain their developmental potential. The presence of fragmented cells is not an indicator of embryo quality.

Evaluating the value of day 0 of an ICSI cycle on indicating laboratory outcome

A number of oocyte characteristics have been associated with fertilization, implantation and live-birth rates, albeit without reaching a consensus. This study aims to delineate possible associations between oocyte characteristics, oocyte behavior during intracytoplasmic sperm injection (ICSI), fertilization potential, and laboratory outcomes. Four-hundred and seventy-seven patients, yielding 3452 oocytes, were enrolled in this prospective observational study from 2015 to 2018. Οoplasm granularity was associated with poor embryo quality and higher probabilities of post-ICSI oocytes and embryos discarded in any developmental stage and never selected for embryo transfer or cryopreservation (p < 0.001). Both sudden or difficult ooplasm aspiration, and high or lack of resistance during ICSI were associated with either a poor Zygote-Score or fertilization failure (p < 0.001). Sudden or difficult ooplasm aspiration and high resistance during ICSI penetration were positively associated with resulting to a post-ICSI oocyte or embryo that would be selected for discard. Evaluation of oocyte characteristics and oocyte behavior during ICSI may provide early information regarding laboratory and cycle outcomes. Particularly, ooplasm granularity, and fragmentation of polar body, along with sudden or difficult ooplasm aspiration and high or lack of resistance during ICSI penetration may hinder the outcome of an ICSI cycle. The associations presented herein may contribute towards development of a grading system or a prediction model. Taking into account information on oocytes and ICSI behavior may effectively assist in enhancing IVF outcome rates.

Assessment of embryo implantation potential with a cloud-based automatic software

RESEARCH QUESTION

Is embryo selection by Dana (automatic software for embryo evaluation) associated with a higher implantation rate in IVF treatments?

DESIGN

A three-phase study for Dana system's validation: creation of a data-cloud of known implantation data (KID) embryos from 1676 transferred embryos; embryo evaluation by Dana considering manual annotations and embryo development videos (389 transferred embryos); and validation of Dana automatic selection, without embryologist's intervention (147 transferred embryos); RESULTS: The implantation rate of the 1021 KID embryos from phase 1 served to set four grades of embryos referring to implantation rate: A = 34%, B = 25%, C = 24%, and D = 19%. Phase 2: a classification ranking according to the unit average distance (UAD) and implantation potential was established: top (UAD ≤0.50), high (UAD = 0.51-0.66), medium (UAD = 0.67-1.03) and low (UAD >1.03). Pregnancy rates were 59%, 46%, 36% and 28%, respectively (P < 0.001). Phase 3: embryos were automatically categorized according to Dana's classification ranking. Most implanted embryos were found in groups top, high and medium (UAD ≤1.03), whereas the implantation rate in group low (UAD >1.03) was significantly lower: 46% versus 25%, respectively (P = 0.037). The twin gestation rate was higher when number of top embryos (UAD ≤0.5) transferred were two (52%) versus one (25%) (P < 0.001).

CONCLUSIONS

Embryo selection based on Dana ranking increases the success of IVF treatments at least in oocyte donation programmes. The multicentre nature of the study supports its applicability at different clinics, standardizing the embryo development's interpretation. Dana's innovation is that the system increases its accuracy as the database grows.

Mining of variables from embryo morphokinetics, blastocyst's morphology and patient parameters: an approach to predict the live birth in the assisted reproduction service

Based on growing demand for assisted reproduction technology, improved predictive models are required to optimize in vitro fertilization/intracytoplasmatic sperm injection strategies, prioritizing single embryo transfer. There are still several obstacles to overcome for the purpose of improving assisted reproductive success, such as intra- and inter-observer subjectivity in embryonic selection, high occurrence of multiple pregnancies, maternal and neonatal complications. Here, we compare studies that used several variables that impact the success of assisted reproduction, such as blastocyst morphology and morphokinetic aspects of embryo development as well as characteristics of the patients submitted to assisted reproduction, in order to predict embryo quality, implantation or live birth. Thereby, we emphasize the proposal of an artificial intelligence-based platform for a more objective method to predict live birth.

mir-320b rs755613466 T>C and mir-27a rs780199251 G>A polymorphisms and the risk of IVF failure in Kurdish women

In vitro fertilization failure is not only the cause of despair among couples and individuals undergoing the treatment, it has also been contributing to the impediment of assistive reproductive technologies' development. MicroRNAs (miRNAs) have been linked to significant events in the reproduction course. The identification of miRNA polymorphisms may provide a good lead for the potential of diagnosis and treatment of unidentified in vitro fertilization (IVF) failure causes. The aim of our study is to explore the association between miRNA polymorphisms (mir-320b T>C and mir-27a G >A) and IVF failure. Our case-control study consisted of 200 Kurdish women in total, 100 with IVF failure and the other 100 control who have had at least two successful pregnancies and no history of pregnancy loss, we used tetra amplification refractory mutation system PCR to identify the polymorphisms within the groups. The TT genotype of mir-320b was found more frequently in IVF failure patients when compared to the healthy women (OR 8.07, CI 2.18-29.78, P = 0.001) and T allele was more present in the case group (OR 1.83, CI 91.04-2.12, P = 0.034), however mir-27a seemed to show no association with IVF failure in regards to genotype and allele frequencies. The difference in genotype and allele frequencies of mir-320b of the two groups may indicate that it has an effect on the target mRNAs and alter the implantation of embryo during IVF cycles.

Identification of differentially expressed microRNAs in outgrowth embryos compared with blastocysts and non-outgrowth embryos in mice

Recurrent implantation failure (RIF) is one of the main causes for the repeated failure of IVF, and the major reason for RIF is thought to be a miscommunication between the embryo and uterus. However, the exact mechanism underlying embryo-uterus cross-talk is not fully understood. The aim of the present study was to identify differentially expressed microRNAs (miRNAs) among blastocysts, non-outgrowth and outgrowth embryos in mice using microarray analysis. A bioinformatics analysis was performed to predict the potential mechanisms of implantation. The miRNA expression profiles differed significantly between non-outgrowth and outgrowth embryos. In all, 3163 miRNAs were detected in blastocysts and outgrowth embryos. Of these, 10 miRNA candidates (let-7b, miR-23a, miR-27a, miR-92a, miR-183, miR-200c, miR-291a, miR-425, miR-429 and miR-652) were identified as significant differentially expressed miRNAs of outgrowth embryos by in silico analysis. The expression of the miRNA candidates was markedly changed during preimplantation embryo development. In particular, let-7b-5p, miR-200c-3p and miR-23a-3p were significantly upregulated in outgrowth embryos compared with non-outgrowth blastocysts. Overall, differentially expressed miRNAs in outgrowth embryos compared with blastocysts and non-outgrowth embryos could be involved in embryo attachment, and interaction between the embryo proper and maternal endometrium during the implantation process.

Review: Recent advances in bovine in vitro embryo production: reproductive biotechnology history and methods

In vitro production (IVP) of embryos and associated technologies in cattle have shown significant progress in recent years, in part driven by a better understanding of the full potential of these tools by end users. The combination of IVP with sexed semen (SS) and genomic selection (GS) is being successfully and widely used in North America, South America and Europe. The main advantages offered by these technologies include a higher number of embryos and pregnancies per unit of time, and a wider range of potential female donors from which to retrieve oocytes (including open cyclic females and ones up to 3 months pregnant), including high index genomic calves, a reduced number of sperm required to produce embryos and increased chances of obtaining the desired sex of offspring. However, there are still unresolved aspects of IVP of embryos that limit a wider implementation of the technology, including potentially reduced fertility from the use of SS, reduced oocyte quality after in vitro oocyte maturation and lower embryo cryotolerance, resulting in reduced pregnancy rates compared to in vivo-produced embryos. Nevertheless, promising research results have been reported, and work is in progress to address current deficiencies. The combination of GS, IVP and SS has proven successful in the commercial field in several countries assisting practitioners and cattle producers to improve reproductive performance, efficiency and genetic gain.

Biodynamic optical assay for embryo viability

Early stage porcine parthenogenetic embryos were evaluated for metabolic activity using a biodynamic microscope (BDM) that images dynamic light scattering using low-coherence digital holography. The microscope has a 45-deg illumination configuration that reduces specular background for the imaging of small translucent samples. The off-axis illumination is compatible with coherence-gated imaging because of volumetric light scattering in which the coherence plane is tilted at half the illumination angle in a three-dimensional tissue target. The BDM was used to profile the viability of porcine parthenotes with normal and with inhibited mitochondrial adenosine triphosphate (ATP) production using Doppler fluctuation spectroscopy. The ATP concentrations in the parthenotes, which are indicative of developmental potential, were validated by a conventional bioluminescence assay. Biodynamic classifications achieved ∼80  %   accuracy correlating sample ATP treatment, providing a quick, label-free surrogate measurement to replace invasive metabolic assays as a candidate for evaluating quality of early embryos in the assisted reproductive technology setting.

Treating Infertility: Current Affairs of Cross-border Reproductive Care

Infertility patients are willing to travel abroad to receive the medical treatment of choice. A 2010 study reported that approximately 25,000 couples travel abroad annually seeking infertility treatment. The purpose of this review is to analyze the criteria and risks related to cross-border reproductive care (CBRC) from the perspective of the patients and explore the issues raised regarding the country of origin and the destination country. A computerized search was performed in PubMed employing respective keywords. The total number of published articles provided by our PubMed search was 1905. Criteria for selecting the destination country include: the economic status, legislation, quality of care and anonymity. Despite the fact that CBRC is becoming a familiar concept, it raises concerns for the practitioner and issues of a social and bioethical nature. Most of them stem from the fact that health care acquires a commercialization aspect. Medical tourism entails several risks, such as misconceptions regarding the destination country, and legal issues arising from differences in the judiciary systems. Larger studies evaluating all aspects of CBRC are imperative. Quality assurance, a consensus and a common platform of practice, along with a system of international governance based on human rights, are a necessity for CBRC patients.

Effect of BMP15 and/or AMH during in vitro maturation of oocytes from involuntarily culled dairy cows

The high metabolic activity to which the dairy cattle are exposed to maintain milk production altered steroid metabolism that affects reproductive physiology and reduce oocyte competence. Our aims were (a) to characterize the competence of immature oocytes collected from dairy cattle based on the expression of genes in cumulus cells (CCs) and (b) to improve oocyte competence to support preimplantation embryo development by the supplementation of maturation medium with bone morphogenetic protein 15 (BMP15) and/or anti-mullerian hormone (AMH). Oocyte donors were identified at the moment of ovary collection and grouped by involuntarily culled dairy cows (Holstein breed) or beef cattle. The embryo development speed to blastocyst of the cull dairy cattle versus beef cattle (control group) was lower. Besides, <10% of oocytes (with CC biopsies) derived from dairy cattle were able to develop to the blastocyst stage. In addition, a higher level of expression and a positive correlation were observed in the expression of most of the genes evaluated (LUM, KRT18, KRT8, CLIC3, BMPR1B, and SLC38A3) in the cumulus-oocyte complexes that produced blastocysts versus those which did not develop correctly (arrested development). Further, use of BMP15 in the maturation of oocytes from dairy cattle seems to increase competence, modulating the expression of OCT4, SOX2, CDX2, GATA6, and TP1 in resulting blastocysts.

Artificial Intelligence-Based Grading Quality of Bovine Blastocyst Digital Images: Direct Capture with Juxtaposed Lenses of Smartphone Camera and Stereomicroscope Ocular Lens

In this study, we developed an online graphical and intuitive interface connected to a server aiming to facilitate professional access worldwide to those facing problems with bovine blastocysts classification. The interface Blasto3Q, where 3Q refers to the three qualities of the blastocyst grading, contains a description of 24 variables that were extracted from the image of the blastocyst and analyzed by three Artificial Neural Networks (ANNs) that classify the same loaded image. The same embryo (i.e., the biological specimen) was submitted to digital image capture by the control group (inverted microscope with 40× magnification) and the experimental group (stereomicroscope with maximum of magnification plus 4× zoom from the cell phone camera). The images obtained from the control and experimental groups were uploaded on Blasto3Q. Each image from both sources was evaluated for segmentation and submitted (only if it could be properly or partially segmented) for automatic quality grade classification by the three ANNs of the Blasto3Q program. Adjustments on the software program through the use of scaling algorithm software were performed to ensure the proper search and segmentation of the embryo in the raw images when they were captured by the smartphone, since this source produced small embryo images compared with those from the inverted microscope. With this new program, 77.8% of the images from smartphones were successfully segmented and from those, 85.7% were evaluated by the Blasto3Q in agreement with the control group.

Non-invasive embryo evaluation and selection using time-lapse monitoring: Results of a randomized controlled study

OBJECTIVE

Continuous monitoring of embryos via time-lapse (TL) provides more information on embryo kinetics and morphology compared to standard daily evaluation. Embryo selection by TL could support single embryo transfer (SET). With SET multiple gestations are avoided and perinatal outcome is improved. Our primary goal was to determine whether selection of a single blastocyst based on an algorithm comprising kinetic and morphologic scores assessed through continuous TL monitoring results in superior clinical outcome compared to embryo selection based on morphology alone. A secondary goal was to assess whether a time-lapse score based on kinetic and morphologic parameters was predictive of implantation.

STUDY DESIGN

Randomized controlled trial performed in two private IVF centers in Hungary. Infertile couples scheduled to undergo 1st or 2nd IVF cycles were enrolled. Female age had to be under 36 years. The intervention was embryo evaluation/selection based on TL algorithm. Patients were randomized to SET with TL monitoring (TL-eSET) vs. SET with standard evaluation (control-eSET). Assuming an increase in pregnancy from 44% to 58%, a sample size of 202 per group was calculated based on the interim analysis at 10% information fraction. The primary outcome of the study was pregnancy rate. Secondary outcomes were miscarriage rates, live birth, perinatal outcome and the ability of a time-lapse score constructed based on kinetic and morphologic parameters to predict implantation. Chi-square tests, likelihood-ratio tests and exact tests were used for the analysis of categorical variables. Continuous variables were compared using independent group t-test and analysis of variance.

RESULTS

The study was closed after three years. Eventually 161 patients were randomized and analyzed (N = 80 TL-eSET and N = 81 control-eSET). Pregnancy rate did not significantly differ between the groups though there was a trend favoring TL selection (TL-eSET: 46.3% vs control-eSET: 34.6%, p = 0.150; OR: 1.628 (95% CI: 0.857-3.092)). The time-lapse score based on morphologic and kinetic parameters was significantly higher for blastocysts that implanted vs. those that did not (14.5 ± 1.8 vs. 12.1 ± 2.9, p = 0.0001). There were no adverse effects of the intervention.

CONCLUSIONS

Selection of a single blastocyst based on information derived from time-lapse monitoring can aid embryo selection for SET.

Are computational applications the "crystal ball" in the IVF laboratory? The evolution from mathematics to artificial intelligence

Mathematics rules the world of science. Innovative technologies based on mathematics have paved the way for implementation of novel strategies in assisted reproduction. Ascertaining efficient embryo selection in order to secure optimal pregnancy rates remains the focus of the in vitro fertilization scientific community and the strongest driver behind innovative approaches. This scoping review aims to describe and analyze complex models based on mathematics for embryo selection, devices, and software most widely employed in the IVF laboratory and algorithms in the service of the cutting-edge technology of artificial intelligence. Despite their promising nature, the practicing embryologist is the one ultimately responsible for the success of the IVF laboratory and thus the one to approve embracing pioneering technologies in routine practice. Applied mathematics and computational biology have already provided significant insight into the selection of the most competent preimplantation embryo. This review describes the leap of evolution from basic mathematics to bioinformatics and investigates the possibility that computational applications may be the means to foretell a promising future for the IVF clinical practice.

Lysophosphatidic acid accelerates development of porcine embryos by activating formation of the blastocoel

Culture media modifications, including the addition of various factors, are important for the in vitro production of oocytes and embryos. In this study, we investigated the effects of lysophosphatidic acid (LPA) on porcine embryo development. Porcine parthenogenetic embryos were cultured with 0, 0.1, 1, and 10 μM LPA for 7 days, or cultured in basic medium until Day 4 and then treated with LPA from Days 4 to 7. No difference in the in vitro development of embryos cultured with LPA for 7 days was observed. Conversely, rates of blastocyst and over-expanded blastocyst formation were higher in the 0.1 and 1 µM LPA-treated versus the other groups of embryos treated from Days 4 to 7. Moreover, formation of early blastocysts occurred earlier and embryo size was larger in LPA-treated compared to control embryos. Expression of Connexin 43 and gap junction and cell adhesion-related genes (GJC1 and CDH1, respectively) was also higher in LPA-treated compared to control embryos. Despite no difference in the blastocyst total cell number between groups, the apoptotic index was lower in the LPA-treated group than in the control group; indeed, BCL2L1 (B-cell lymphoma 2-like protein 1) expression increased while BAK (Bcl-2 homologous antagonist killer) decreased in the LPA-treated group. Thus, addition of LPA to the medium from Days 4 to 7 of culture improves blastocyst formation and aids the development of preimplantation embryos.

Effect of oocyte vitrification on embryo quality: time-lapse analysis and morphokinetic evaluation

OBJECTIVE

To analyze whether oocyte vitrification may affect subsequent embryo development from a morphokinetic standpoint by means of time-lapse imaging.

DESIGN

Observational cohort study.

SETTING

University-affiliated private IVF center.

PATIENT(S)

Ovum donation cycles conducted with the use of vitrified (n = 631 cycles; n = 3,794 embryos) or fresh oocytes (n = 1,359 cycles; n = 9,935 embryos) over 2 years.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

Embryo development was analyzed in a time-lapse imaging incubator. The studied variables included time to 2 cells (t2), 3 cells (t3), 4 cells (t4), 5 cells (t5), morula (tM), and cavitated, early, and hatching blastocyst (tB, tEB, tHB) as well as 2nd cell cycle duration (cc2 = t3 - t2). All of the embryos were classified according to the hierarchic tree model currently used for embryo selection. The analyzed variables were compared with the use of analysis of variance or chi-square and included 95% confidence intervals (CIs).

RESULT(S)

The embryos that originated from vitrified oocytes showed a delay of ∼1 hour from the first division to 2 cells (t2) to the time of blastulation (tB). The embryos that originated from vitrified oocytes showed a delay of ∼1 hour from the 1st division to 2 cells (t2) to the time of blastulation (tB) (P<.05). The proportions of embryos allocated to categories A-E in the hierarchical tree were similar between groups. No differences in implantation rates between the fresh (51.3% [95% CI 47.1%-55.7%]) and vitrified (46.4% [95% CI 38.4%-54.4%]) groups were found.

CONCLUSION(S)

The embryo quality of vitrified oocytes was not impaired: cc2, quality according to our hierarchic morphokinetic model, and implantation rates were similar between fresh and vitrified oocytes. However, morphokinetic differences were observed from t2 to tB. Our main study limitation was the retrospective nature of the analysis, although a large database was studied.

A Method Based on Artificial Intelligence To Fully Automatize The Evaluation of Bovine Blastocyst Images

Morphological analysis is the standard method of assessing embryo quality; however, its inherent subjectivity tends to generate discrepancies among evaluators. Using genetic algorithms and artificial neural networks (ANNs), we developed a new method for embryo analysis that is more robust and reliable than standard methods. Bovine blastocysts produced in vitro were classified as grade 1 (excellent or good), 2 (fair), or 3 (poor) by three experienced embryologists according to the International Embryo Technology Society (IETS) standard. The images (n = 482) were subjected to automatic feature extraction, and the results were used as input for a supervised learning process. One part of the dataset (15%) was used for a blind test posterior to the fitting, for which the system had an accuracy of 76.4%. Interestingly, when the same embryologists evaluated a sub-sample (10%) of the dataset, there was only 54.0% agreement with the standard (mode for grades). However, when using the ANN to assess this sub-sample, there was 87.5% agreement with the modal values obtained by the evaluators. The presented methodology is covered by National Institute of Industrial Property (INPI) and World Intellectual Property Organization (WIPO) patents and is currently undergoing a commercial evaluation of its feasibility.

Predictive value of spindle retardance in embryo implantation rate

PURPOSE

We evaluated the relationship between meiotic spindle characteristics and in vitro fertilization cycle outcome.

METHODS

Five hundred sixty-nine oocytes from 86 in vitro fertilization cycles were analyzed for fertilization and subsequent implantation rates. Oocytes were assessed for maturation status. The oocytes and embryos were cultured in sequential and nonsequential media (G Series, Vitrolife, Sweden) and incubated in 6% CO₂, 5% O₂ at 37 °C. Two hours following oocyte decumulation (38-39 h post-hCG/GnRH administration) and prior to microinjection, the structure of the meiotic spindle was assessed using the Oosight Imaging System (CRI, UK).

RESULTS

Four hundred fifty-six oocytes (80.5%) had a visible meiotic spindle, 82 (14.7%) had no meiotic spindle, and 31 (5.5%) were in telophase I. Oocytes exhibiting a meiotic spindle had a significantly higher fertilization rate and a lower rate of abnormal fertilization. Implantation data were obtained for 195 of the embryos transferred. The implantation rate for embryos derived from oocytes with a meiotic spindle was 32.9%, while in embryos originating from oocytes without a meiotic spindle and oocytes in telophase, this value dropped significantly (8.8 and 0%, respectively). To determine the correlation between retardance values and implantation rate for each oocyte, we established four groups, finding a range of retardance values with significantly higher implantation rates (27.5, 21, 29.3, and 53.8%, respectively).

CONCLUSION

Meiotic spindle imaging may be a valuable tool for prediction of oocyte quality, and retardance values of meiotic spindles, together with classical morphological classification, can be useful to select embryos with a higher implantation potential.

Raman spectrum: A potential biomarker for embryo assessment during in vitro fertilization

The aim of the study was to investigate whether Raman spectrum is consistent with the morphological scoring of the embryo of day 3 during in vitro fertilization (IVF). The spent culture media of embryo of day 3 from 10 patients were collected and analyzed. The samples were analyzed using Raman spectroscopy and graded according to the standard embryo scoring system simultaneously. Data showed that the Raman spectra obtained from the droplet of media were useful, as they can act as the characteristic signature for protein and amino acids. The Raman biospectroscopy-based metabonomics profiling of spent media was consistent with the result of conventional morphological evaluation. In conclusion, this technology offers great potential for the development of tools allowing rapid non-invasive assessment of the quality of embryo of day 3 during IVF.

Predicting pregnancy rate following multiple embryo transfers using algorithms developed through static image analysis

Single-embryo image assessment involves a high degree of inaccuracy because of the imprecise labelling of the transferred embryo images. In this study, we considered the entire transfer cycle to predict the implantation potential of embryos, and propose a novel algorithm based on a combination of local binary pattern texture feature and Adaboost classifiers to predict pregnancy rate. The first step of the proposed method was to extract the features of the embryo images using the local binary pattern operator. After this, multiple embryo images in a transfer cycle were considered as one entity, and the pregnancy rate was predicted using three classifiers: the Real Adaboost, Gentle Adaboost, and Modest Adaboost. Finally, the pregnancy rate was determined via the majority vote rule based on classification results of the three Adaboost classifiers. The proposed algorithm was verified to have a good predictive performance and may assist the embryologist and clinician to select embryos to transfer and in turn improve pregnancy rate.

Time-lapse embryoscopy

Time-lapse (TL) embryo monitoring is the latest technology that is proposed for embryo evaluation and selection for transfer. TL technology enables us to collect significantly more information about the in vitro development of the embryos that can be obtained through the daily-once evaluation under the light microscope. In addition, the embryos do not need to be removed from the culture environment for this. The extra morphokinetic information and the undisturbed culture conditions could both be beneficial for the cultured embryo cohort. Many morphokinetic parameters have been tested in relation to variety of laboratory (e.g. blastocyst development) and clinical (implantation and live-birth rate) outcomes. Most of these studies are retrospective in nature and suffer from methodological problems (heterogeneous patient population, culture conditions not standardized, and small sample size). Several groups attempted to build algorithms, however, have not yet been confirmed externally as attempts so far could not reproduce the expected predictive abilities. Therefore, these algorithms cannot be universally accepted. The latest algorithm proposed for embryo selection was developed based on data from 24 clinics using local stimulation and laboratory procedures. It groups embryos into five categories (KIDScore) based on in and out of range kinetic events. The algorithm was tested in subsets of patients using various fertilization methods or culture conditions and its predictive ability remained the same. The authors, therefore, feel comfortable to recommend it for routine use in any laboratory using TL technology. There is, however, still limited prospective, randomized trial data testing the algorithms. This article reviews TL technology, retrospective and prospective reports on various morphokinetic parameters, and the benefits and shortcomings of currently available algorithms.

Methods for assessing the quality of mammalian embryos: How far we are from the gold standard?

Morphological embryo classification is of great importance for many laboratory techniques, from basic research to the ones applied to assisted reproductive technology. However, the standard classification method for both human and cattle embryos, is based on quality parameters that reflect the overall morphological quality of the embryo in cattle, or the quality of the individual embryonic structures, more relevant in human embryo classification. This assessment method is biased by the subjectivity of the evaluator and even though several guidelines exist to standardize the classification, it is not a method capable of giving reliable and trustworthy results. Latest approaches for the improvement of quality assessment include the use of data from cellular metabolism, a new morphological grading system, development kinetics and cleavage symmetry, embryo cell biopsy followed by pre-implantation genetic diagnosis, zona pellucida birefringence, ion release by the embryo cells and so forth. Nowadays there exists a great need for evaluation methods that are practical and non-invasive while being accurate and objective. A method along these lines would be of great importance to embryo evaluation by embryologists, clinicians and other professionals who work with assisted reproductive technology. Several techniques shows promising results in this sense, one being the use of digital images of the embryo as basis for features extraction and classification by means of artificial intelligence techniques (as genetic algorithms and artificial neural networks). This process has the potential to become an accurate and objective standard for embryo quality assessment.

Non-invasive methods for embryo selection

With the widespread use of assisted reproduction, a simple and practical method for embryo selection is needed to optimize the chances of pregnancy while diminishing the incidence of multiple pregnancy and its accompanying problems. Many non-invasive methods for embryo selection have been proposed and some are more promising than others. This review summarizes these methods and attempts to evaluate them in the light of the best currently available evidence and to find out whether any of them is ripe for replacing or supplementing the time-honored method of morphological assessment.

Zeta Sperm Selection Improves Pregnancy Rate and Alters Sex Ratio in Male Factor Infertility Patients: A Double-Blind, Randomized Clinical Trial

Background

Selection of sperm for intra-cytoplasmic sperm injection (ICSI) is usually considered as the ultimate technique to alleviate male-factor infertility. In routine ICSI, selection is based on morphology and viability which does not necessarily preclude the chance injection of DNA-damaged or apoptotic sperm into the oocyte. Sperm with high negative surface electrical charge, named “Zeta potential”, are mature and more likely to have intact chromatin. In addition, X-bearing spermatozoa carry more negative charge. Therefore, we aimed to compare the clinical outcomes of Zeta procedure with routine sperm selection in infertile men candidate for ICSI.

Materials and Methods

From a total of 203 ICSI cycles studied, 101 cycles were allocated to density gradient centrifugation (DGC)/Zeta group and the remaining 102 were included in the DGC group in this prospective study. Clinical outcomes were com- pared between the two groups. The ratios of Xand Y bearing sperm were assessed by fluorescence in situ hybridization (FISH) and quantitative polymerase chain reaction (qPCR) methods in 17 independent semen samples.

Results

In the present double-blind randomized clinical trial, a significant increase in top quality embryos and pregnancy rate were observed in DGC/Zeta group compared to DGC group. Moreover, sex ratio (XY/XX) at birth significantly was lower in the DGC/Zeta group compared to DGC group despite similar ratio of X/Y bearings sper- matozoa following Zeta selection.

Conclusion

Zeta method not only improves the percentage of top embryo quality and pregnancy outcome but also alters the sex ratio compared to the conventional DGC method, despite no significant change in the ratio of Xand Ybearing sperm population (Registration number: IRCT201108047223N1).

Can IVF influence human evolution?

IVF, a procedure in which pharmacological and technological manipulation is used to promote pregnancy, offers help to infertile couples by circumventing selection at the most fundamental level. Fertility is clearly one of the key fitness-promoting drivers in all forms of sexually reproducing life, and fertilization and pregnancy are fundamental evolutionary processes that involve a range of pre- and post-zygotic screening mechanisms. Here, we discuss the various selection and screening factors involved in fertilization and pregnancy and assess IVF practices in light of these factors. We then focus on the possible consequences of these differences in selection pressures, mainly at the individual but also at the population level, to evaluate whether changes in the reproducing genotype can affect human evolution. The aim of the article is not to argue for or against IVF, but to address aspects of assisted reproduction in an evolutionary context.

The IMSI Procedure Improves Laboratory and Clinical Outcomes Without Compromising the Aneuploidy Rate When Compared to the Classical ICSI Procedure

PURPOSE

The intracytoplasmic morphologically selected sperm injection (IMSI) procedure has been associated with better laboratory and clinical outcomes in assisted reproduction technologies. Less information is available regarding the relationship between embryo aneuploidy rate and the IMSI procedure. The aim of this study is to compare the clinical outcomes and chromosomal status of IMSI-derived embryos with those obtained from intracytoplasmic sperm injection (ICSI) in order to establish a clearer view of the benefits of IMSI in infertile patients.

METHODS

We retrospectively analyzed a total of 11 cycles of IMSI and 20 cycles of ICSI with preimplantation genetic diagnosis. The fertilization rate, cleavage rate, embryo quality, blastocyst development, aneuploidy rate, pregnancy rate, implantation rate, and miscarriage rate were compared between the groups.

RESULTS

Similar rates of fertilization (70% and 73%), cleavage (98% and 100%), and aneuploidy (76.9% and 70.9%) were observed in the IMSI and ICSI groups, respectively. The IMSI group had significantly more good quality embryos at day 3 (95% vs 73%), higher blastocyst development rates (33% vs 19%), and greater number of hatching blastocysts (43% vs 28%), cycles with at least one blastocyst at day 5 (55% vs 35%), and blastocysts with good trophoectoderm morphology (21% vs 6%) compared with the ICSI group (P < 0.001). Significantly higher implantation rates were observed in the IMSI group compared with the ICSI group (57% vs 27%; P < 0.05). Pregnancy and miscarriage rates were similar in both groups (80% vs 50% and 0% vs 33%, respectively).

CONCLUSION

The IMSI procedure significantly improves the embryo quality/development by increasing the implantation rates without affecting the chromosomal status of embryos. There is a tendency for the IMSI procedure to enhance the pregnancy rates and lower the miscarriage rates when compared with ICSI.