Mitochondrial DNA Copy Number in Cleavage Stage Human Embryos—Impact on Infertility Outcome

A retrospective case control study was undertaken at the molecular biology department of a private center for reproductive medicine in order to determine whether any correlation exists between mitochondrial DNA (mtDNA) content of cleavage-stage preimplantation embryos and their developmental potential. A total of 69 couples underwent IVF treatment (averaged women age: 36.5, SD 4.9) and produced a total of 314 embryos. A single blastomere was biopsied from each embryo at the cleavage stage (day-3 post-fertilization) subjected to low-pass next generation sequencing (NGS), for the purpose of detecting aneuploidy. For each sample, the number of mtDNA reads obtained after analysis using NGS was divided by the number of reads attributable to the nuclear genome. The mtDNA copy number amount was found to be higher in aneuploid embryos than in those that were euploid (mean mtDNA ratio ± SD: 6.3 ± 7.5 versus 7.1 ± 5.8, p < 0.004; U Mann–Whitney test), whereas no statistically significant differences in mtDNA content were seen in relation to embryo morphology (6.6 ± 4.8 vs. 8.5 ± 13.6, p 0.09), sex (6.6 ± 4.1 vs. 6.2 ± 6.8, p 0.16), maternal age (6.9 ± 7.8 vs. 6.7 ± 4.5, p 0.14) or its ability to implant (7.4 ± 6.6 vs. 5.1 ± 4.6, p 0.18). The mtDNA content cannot serve as a useful biomarker at this point in development. However, further studies investigating both quantitative and qualitative aspects of mtDNA are still required to fully evaluate the relationship between mitochondrial DNA and human reproduction.

Does Conventional Morphological Evaluation Still Play a Role in Predicting Blastocyst Formation?

BackgroundAdvanced models including time-lapse imaging and artificial intelligence technologies have been used to predict blastocyst formation. However, the conventional morphological evaluation of embryos is still widely used. The purpose of the present study was to evaluate the predictive power of conventional morphological evaluation regarding blastocyst formation.MethodsRetrospective evaluation of data from 15613 patients receiving blastocyst culture from January 2013 through December 2020 in our institution were reviewed. Generalized estimating equations (GEE) were used to establish the morphology-based model. To estimate whether including more features regarding patient characteristics and cycle parameters improve the predicting power, we also establish models including 27 more features with either LASSO regression or XGbosst. The predicted number of blastocyst were associated with the observed number of the blastocyst and were used to predict the blastocyst transfer cancellation either in fresh or frozen cycles. ResultsBased on early cleavage and routine observed morphological parameters (cell number, fragmentation, and symmetry), the GEE model predicted blastocyst formation with an AUC of 0.779(95%CI: 0.77-0.787) and an accuracy of 74.7%(95%CI: 73.9%-75.5%) in the validation set. LASSO regression model and XGboost model based on the combination of cycle characteristics and embryo morphology yielded similar predicting power with AUCs of 0.78(95%CI: 0.771-0.789) and 0.754(95%CI: 0.745-0.763), respectively. For per-cycle blastocyst yield, the predicted number of blastocysts using morphological parameters alone strongly correlated with observed blastocyst number (r=0.897, P<0.0001) and predicted blastocyst transfer cancel with an AUC of 0.926((95%CI: 0.911-0.94). ConclusionThe data suggested that routine morphology observation remained a feasible tool to support an informed decision regarding the day of transfer. However, models based on the combination of cycle characteristics and embryo morphology do not increase the predicting power significantly.

Evaluation of the quality of embryo based on morphology cultured at low oxygen concentration

Objectives: evaluating the quality of embryo morphology cultured at low oxygen concentration (5%) at different stages of embryonic development: day 3, day 5. Methods: the present study examined 168 IVF/ICSI cycles from October 2019 to February 2021 at the Assisted Reproductive Center, 16A Ha Dong General Hospital. Embryos were randomly assigned to 2 groups: group 1 used a K-system G-210 tri-gas incubator (Australia) (5% O2, 5% CO2, 90% N2) while group 2 used a Thermo Scientific 371 dual-gas incubator (Denmark) (5% CO2, 75% N2 with 20% atmospheric Oxygen concentration). Participants in the study were patients younger than 37 years old, with AMH>1.2 ng/ml, and AFC≥4. Mature oocytes were injected with sperm, and cultured in a sequential medium (G1,G2-PLUSTM). Embryologists assessed embryos on the day of fertilisation, days 3, 5, and compared the results of the two groups, using the method of descriptive statistics and T-test. The results revealed an insignificant difference in fertilisation rate and the quality of cleavages cultured in these 2 groups (percentages of good- and average quality cleavages were, in turn, 77.28±4.62% và 77.99±5.03%, at p>0.05, number of poor quality cleavages were, in turn, 1.71±0.38 vs 1.97±0.49 with p>0.05). The results on day 5 embryo showed that the percentage of blastocysts (from fertilisation) and the percentage of morphologically good- and average-quality blastocysts tended to increase higher when cultured in 5% oxygen concentration (p<0.05) compared with the 20% one (57.79±3.60% and 53.05±4.50%, 78.62±4.42% and 70.97±5.67%, respectively). Conclusions: embryo cultured in a low oxygen concentration helps embryos develop better on day 5 than when cultured at atmospheric concentrations

P–199 A case report to suggest that there must be other mutations than PATL2 or TUBB8 to cause oocyte maturation arrest

Study question What causes our patient’s repeated almost complete oocyte maturation arrest (OMA)? Summary answer Since we did not detect PATL2 and TUBB8 mutations, both known to cause OMA, this case was likely caused by mutations in HUS1 and ITGB3 What is known already OMA has been associated with loss-of-function in key genes, such as PATL2 and TUBB8. Such patients have, however, uniformly have been unable to conceive with IVF Study design, size, duration We here report the case of repeatedly presenting patient between 2009 until 2020 (age 30 at 1st and 41 at last visit). Participants/materials, setting, methods The couple underwent 7 IVF treatments under several ovarian stimulation protocols at different gonadotropin dosages and in different preparations to try to recruit mature eggs. She conceived in her 2nd IVF cycle in 2009 and delivered uneventfully in 2010. She then conceived spontaneously and delivered a healthy boy in 2014. The couple since then has been attempting another pregnancy. Remarkably, in all IVF cycles all eggs but one arrested at prophase. Main results and the role of chance The female demonstrates abnormally high ovarian reserve for age (AMH=5.9 ng/mL in 2019) (mean, 10.6 oocytes). In all cycles, all but one retrieved were immature. In vitro maturation rate for the GV oocytes was 28%. Resultant M2s, however, demonstrated morphological abnormalities, such as giant polar bodies. In vivo M2s, in contrast, were always morphologically unremarkable, and their fertilization rate was 85%. Embryo morphology deteriorated appreciatively with advancing age. Sanger sequencing for TUBB8 and PATL2 genes were unremarkable. Whole genome sequencing of her and her sister (who had no fertility problems) revealed mutations of genes belonging to the integrin family (ITGB3) and DNA repair checkpoint (HUS1), both of which could be determinants in the observed maturation arrest. Limitations, reasons for caution A functional study, coupled with imaging of the discarded material, will likely offer further information regarding the mechanisms leading to OMA in this female. Wider implications of the findings: This case report represents a new phenotype of female infertility, characterized by almost complete maturation arrest which, however, still offers opportunity for pregnancy. Further isolation of underlying mutation(s) may offer additional insights about checkpoints required for the transition of prophase to metaphase in human oocytes. Trial registration number NA

P–080 Higher sperm DNA fragmentation reduces the proportion of good quality embryos at day 5 on IVF and ICSI cycles from unselected males

Study question Does sperm DNA fragmentation (SDF) reduce the ratio of good-quality embryos in day 3 (D3) and day 5 (D5) of embryonic development? Summary answer High sperm DNA fragmentation (SDF &gt;15%) is associated with poor embryo quality at blastocyst-stage per cycle in unselected patients undergoing IVF and ICSI. What is known already It has been shown that the proportion of spermatozoa with DNA fragmentation is higher in infertile men than in semen from fertile men. However, the controversy regarding the impact that sperm genome damage can have on IVF or ICSI treatments is evident in the published literature. The effects of SDF would become evident after activation of the embryonic genome at 8-cell stage, compromising not only the quality of the embryos obtained, but also the reproductive outcomes, as reduced implantation rates, higher miscarriages rates and thus, a decreased chance of pregnancy. Study design, size, duration This multicentric observational retrospective study included 1339 couples who underwent 2759 IVF-ICSI cycles using autologous oocytes from January 2000 to March 2019. All men have an SDF test in their ejaculated spermatozoa by TUNEL assay (Terminal deoxynucleotidyl transferase dUTP nick end labeling). The subjects were divided into two groups according to their sperm DNA integrity: low (≤15%) (n = 2287 cycles) or high (&gt;15%) (n = 472) SDF. Participants/materials, setting, methods Embryo quality was assessed complying morphological standards at cleavage-stage on D3 and at blastocyst-stage on D5 (inner cell mass (ICM) and trophectoderm (TE) grade (A, B, C or D)) in according to ASEBIR’s embryo selection criteria, being embryos of good quality those categorized as A+B. The outcomes were calculated in relation to the total number of zygotes obtained. The results were compared by Student t test; p value &lt;0.05 was considered significant. Main results and the role of chance The SDF average of the low group was 5.8% (95% CI 5.6–5.9) whereas in high group was 23.7% (95% CI 23.0–24.4). The female age was equal, 37.1 years (95%CI 37.0–37.2) and 37.1 years (95% CI 36.8–37.4) respectively. A total of 9796 embryos were evaluated. The optimal cleavage-stage embryo rate per cycle was 25.0% (95% CI 21.7–28.3) (8.0 average cells number, 1.5 embryo fragmentation average, symmetry 1, mononucleated cells) versus 26.7% (95%CI 19.1–34.2) (7.9 average cells number, 1.8 embryo fragmentation average, symmetry 1, mononucleated cells) when comparing between groups (p &lt; 0.001). Blastocyst-stage arrival rate (number of embryos at D5) per cycle was 55.8% (95% CI 54.3–57.2) in ≤ 15% SDF group (embryo quality score was ICM A:12.1%, B:69.5%, C:8.8%, D:4.5%; TE A: 7.5%, B:42.2%, C:42.2%, D:8.1%) and 55.9% (95% CI 52.8–59.1) in the &gt;15% SDF group (ICM A:12.0%, B:68.7%, C:10.6%, D: 5.2%; TE A:9.1%, B:44.8%, C:37.8%, D:8.3%) (p &lt; 0.001). The good quality blastocyst rate per cycle was significantly higher in the group with SDF ≤15%, 27.7% (95%CI 26.5–29.0) versus SDF &gt;15% (27.4% (95%CI 24.6–30.2)). Of the total number of blastocysts, the proportion of A+B blastocyst was 60.5% (95% CI 58.3–62.7) and 64.2% (95% CI 59.2–69.2) (p &lt; 0.001), respectively. Limitations, reasons for caution The retrospective and multicenter nature of this study leads to uncontrolled biases derived from the clinical practice. Although the results were not adjusted for female’s age, it was not statistically different between groups. Embryo morphology evaluation was performed by senior embryologists, it still remains a subjective evaluation, though. Wider implications of the findings: In this study, a higher amount of data was compiled so that a large number of embryos were analyzed. The DNA integrity of the sperm may be an important consideration when poor quality embryos were obtained in the previous cycle when deciding on the next clinical strategy to apply. Trial registration number NA

O-222 An artificial intelligence model that was trained on pregnancy outcomes for embryo viability assessment is highly correlated with Gardner Score

Study question Do artificial intelligence (AI) models used to assess embryo viability (based on pregnancy outcomes) also correlate with known embryo quality measures such as Gardner score? Summary answer An AI for embryo viability assessment also correlated with Gardner score, further substantiating the use of AI for assessment and selection of good quality embryos. What is known already The Gardner score consists of three separate components of embryo morphology that are graded individually, then combined to give a final score describing Day 5 embryo (blastocyst) quality. Evidence suggests the Gardner score has some correlation with clinical pregnancy. We hypothesized that an AI model trained to evaluate likelihood of clinical pregnancy based on fetal heartbeat (in clinical use globally) would also correlate with components of the Gardner score itself. We also compared the ability of the AI and Gardner score to predict pregnancy outcomes. Study design, size, duration This study involved analysis of a prospectively collected dataset of single static Day 5 embryo images with associated Gardner scores and AI viability scores. The dataset comprised time-lapse images of 1,485 embryos (EmbryoScope) from 638 patients treated at a single in vitro fertilization (IVF) clinic between November 2019 and December 2020. The AI model was not trained on data from this clinic. Participants/materials, setting, methods Average patient age was 35.4 years. Embryologists manually graded each embryo using the Gardner method, then subsequently used the AI to obtain a score between 0 (predicted non-viable, unlikely to lead to a pregnancy) and 10 (predicted viable, likely to lead to a pregnancy). Correlation between the AI viability score and Gardner score was then assessed. Main results and the role of chance The average AI score was significantly correlated with the three components of the Gardner score: expansion grade, inner cell mass (ICM) grade, and trophectoderm grade. Average AI score generally increased with advancing blastocyst developmental stage. Blastocysts with expansion grades of ≥ 3 are generally considered suitable for transfer. This study showed that embryos with expansion grade 3 had lower AI scores than those with grades 4-6, consistent with a reduced pregnancy rate. AI correlation with trophectoderm grade was more significant than with ICM grade, consistent with studies demonstrating that trophectoderm grade is more important than ICM in determining clinical pregnancy likelihood. The AI predicted Gardner scores of ≥ 2BB with an accuracy of 71.7% (sensitivity 75.1%, specificity 45.9%), and an AUC of 0.68. However, when used to predict pregnancy outcome, the AI performed 27.9% better than the Gardner score (accuracies of 49.8% and 39.0% respectively). Even though the AI was highly correlated with the Gardner score, the improved efficacy for predicting pregnancy suggests that a) the AI provides an advantage in standardization of scoring over the manual and subjective Gardner method, and b) the AI is likely identifying and evaluating morphological features of embryo quality that are not captured by the Gardner method. Limitations, reasons for caution The Gardner score is not a linear score, creating challenges with setting a suitable threshold relating to the prediction of pregnancy. The 2BB treshold was chosen based on literature (Munné et al 2019) and verified by experienced embryologists. This correlative study may also require additional confirmatory studies on independent datasets. Wider implications of the findings The correlation between AI scores and known features of embryo quality (Gardner score) substantiates the use of the AI for embryo assessment. The AI score provides further insight into components of the Gardner score, and may detect morphological features related to clinical pregnancy beyond those evaluated by the Gardner method. Trial registration number Not applicable