Health professionals' perspective on the applicability of AO Spine PROST (patient reported outcome Spine trauma) in people with a motor-complete traumatic or non-traumatic spinal cord injury.

PURPOSE: The AO Spine PROST (Patient Reported Outcome Spine Trauma) was developed for people with spine trauma and minor or no neurological impairment. The purpose is to investigate health professionals' perspective on the applicability of the AO Spine PROST for people with motor-complete traumatic or non-traumatic spinal cord injury (SCI), using a discussion meeting and international survey study. METHODS: A discussion meeting with SCI rehabilitation physicians in the Netherlands was performed, followed by a worldwide online survey among the AO Spine International community, involved in the care of people with SCI. Participants rated the comprehensibility, relevance, acceptability, feasibility and completeness of the AO Spine PROST on a 1-5 point scale (5 most positive). Comments could be provided per question. RESULTS: The discussion meeting was attended by 13 SCI rehabilitation physicians. The survey was completed by 196 participants. Comprehensibility (mean ± SD: 4.1 ± 0.8), acceptability (4.0 ± 0.8), relevance (3.9 ± 0.8), completeness (3.9 ± 0.8), and feasibility (4.1 ± 0.7) of the AO Spine PROST were rated positively for use in people with motor-complete traumatic or non-traumatic SCI. Only a few participants questioned the relevance of items on the lower extremities (e.g., walking) or missed items on pulmonary functioning and complications. Some recommendations were made for improvement in instructions, terminology and examples of the tool. CONCLUSION: Health professionals found the AO Spine PROST generally applicable for people with motor-complete traumatic or non-traumatic SCI. This study provides further evidence for the use of the AO Spine PROST in spine trauma care, rehabilitation and research, as well as suggestions for its further development.

PROST: AlphaFold2-aware Sequence-Based Predictor to Estimate Protein Stability Changes upon Missense Mutations.

An essential step in engineering proteins and understanding disease-causing missense mutations is to accurately model protein stability changes when such mutations occur. Here, we developed a new sequence-based predictor for the protein stability (PROST) change (Gibb's free energy change, ΔΔG) upon a single-point missense mutation. PROST extracts multiple descriptors from the most promising sequence-based predictors, such as BoostDDG, SAAFEC-SEQ, and DDGun. RPOST also extracts descriptors from iFeature and AlphaFold2. The extracted descriptors include sequence-based features, physicochemical properties, evolutionary information, evolutionary-based physicochemical properties, and predicted structural features. The PROST predictor is a weighted average ensemble model based on extreme gradient boosting (XGBoost) decision trees and an extra-trees regressor; PROST is trained on both direct and hypothetical reverse mutations using the S5294 (S2647 direct mutations + S2647 inverse mutations). The parameters for the PROST model are optimized using grid searching with 5-fold cross-validation, and feature importance analysis unveils the most relevant features. The performance of PROST is evaluated in a blinded manner, employing nine distinct data sets and existing state-of-the-art sequence-based and structure-based predictors. This method consistently performs well on frataxin, S217, S349, Ssym, S669, Myoglobin, and CAGI5 data sets in blind tests and similarly to the state-of-the-art predictors for p53 and S276 data sets. When the performance of PROST is compared with the latest predictors such as BoostDDG, SAAFEC-SEQ, ACDC-NN-seq, and DDGun, PROST dominates these predictors. A case study of mutation scanning of the frataxin protein for nine wild-type residues demonstrates the utility of PROST. Taken together, these findings indicate that PROST is a well-suited predictor when no protein structural information is available. The source code of PROST, data sets, examples, and pretrained models along with how to use PROST are available at https://github.com/ShahidIqb/PROST and https://prost.erc.monash.edu/seq.

Reliability, validity and responsiveness of the Dutch version of the AOSpine PROST (Patient Reported Outcome Spine Trauma).

PURPOSE: To validate the Dutch version of AOSpine PROST (Patient Reported Outcome Spine Trauma). METHODS: Patients were recruited from two level-1 trauma centers from the Netherlands. Next to the AOSpine PROST, patients also filled out SF-36 for concurrent validity. Descriptive statistics were used to analyze the characteristics. Content validity was assessed by evaluating the number of inapplicable or missing questions. Also floor and ceiling effects were analyzed. Internal consistency was assessed by calculating Cronbach's α and item-total correlation coefficients (itcc). Spearman correlation tests were performed within AOSpine PROST items and in correlation with SF-36. Test-retest reliability was analyzed using Intraclass Correlation Coefficients (ICC). Responsiveness was assessed by calculating effect sizes (ES) and standardized response mean (SRM). Factor analysis was performed to explore any dimensions within AOSpine PROST. RESULTS: Out of 179 enrolled patients, 163 (91.1%) were included. Good results were obtained for content validity. No floor or ceiling effects were seen. Internal consistency was excellent (Cronbach's α = 0.96, itcc 0.50-0.86), with also good Spearman correlations (0.25-0.79). Compared to SF-36, the strongest correlation was seen for physical functioning (0.79; p < .001). Also test-retest reliability was excellent (ICC = 0.92). Concerning responsiveness analysis, very good results were seen with ES = 1.81 and SRM = 2.03 (p < 0.001). Factor analysis revealed two possible dimensions (Eigenvalues > 1), explaining 65.4% of variance. CONCLUSIONS: Very satisfactory results were obtained for reliability, validity and responsiveness of the Dutch version of AOSpine PROST. Treating surgeons are encouraged to use this novel and validated tool in clinical setting and research to contribute to evidence-based and patient-centered care.

Are there moral differences between maternal spindle transfer and pronuclear transfer?

This paper examines whether there are moral differences between the mitochondrial replacement techniques that have been recently developed in order to help women afflicted by mitochondrial DNA diseases to have genetically related children absent such conditions: maternal spindle transfer (MST) and pronuclear transfer (PNT). Firstly, it examines whether there is a moral difference between MST and PNT in terms of the divide between somatic interventions and germline interventions. Secondly, it considers whether PNT and MST are morally distinct under a therapy/creation optic. Finally, it investigates whether there is a moral difference between MST and PNT from a human embryo destruction point of view. I conclude, contra recent arguments, that regarding the first two points there is no moral differences between PNT and MST; and that regarding the third one MST is morally preferable to PNT, but only if we hold a gradualist account of the moral value of human embryos where zygotes have slight moral value.

The oviduct: a neglected organ due for re-assessment in IVF.

The oviduct has long been considered a 'pipeline', a tube allowing transit of spermatozoa and embryos; this perspective has been reinforced by the success of human IVF. Evidence accumulated over several decades, however, indicates that embryos can modulate the metabolism of tubal cells in their environment. Human IVF culture media is based on formulations that pass mouse embryo assays as quality control: the requirements of mouse embryos differ from those of human embryos, and therefore conditions for human IVF are far removed from the natural environment of the oviduct. The preimplantation environment, both in vitro and in vivo, is known to affect the health of offspring through mechanisms that influence imprinting. Recent studies also show that male accessory glands act in synergy with the oviduct in providing an optimal environment, and this represents a further perspective on the oviduct's contribution to harmonious embryo development and subsequent long-term health. The metabolism of the human embryo is far from being understood, and a 'return' to in-vivo conditions for preimplantation development is worthy of consideration. Although results obtained in rodents must be interpreted with caution, lessons learned from animal embryo culture must not be neglected.

Zygote intrafallopian tube transfer versus intrauterine cleavage or blastocyst stage transfer after intracytoplasmic sperm injection cycles in patients with repeated implantation failure: A prospective follow-up study.

AIM: This study aimed to compare the outcomes between zygote intrafallopian transfer (ZIFT) with intrauterine day-3 (cleavage stage) embryo transfer and intrauterine day-5 (blastocyst stage) embryo transfer in patients undergoing intracytoplasmic sperm injection. MATERIAL AND METHODS: This prospective study was performed at Royan Institute, Tehran, Iran, between January 2012 and January 2014. Two hundred fifty women with more than three unexplained implantation failures were divided non-randomly into three groups according to embryonic age and methods used as follows: (i) intrauterine cleavage-stage embryo transfer (n = 100); (ii) intrauterine blastocyst-stage embryo transfer (n = 50); and (iii) ZIFT (n = 100). Implantation, clinical pregnancy, miscarriage and live birth rates were our main outcomes. RESULTS: Patients' characteristics and ovarian response were comparable among the three groups. Implantation rate (56.1% vs 27.9%) was significantly higher in the blastocyst group as compared to the ZIFT group; however, clinical pregnancy rate (38% vs 23%) was not statistically significantly different between the two groups, but due to the significantly higher miscarriage rate (34.7% vs 5.3%) in the ZIFT group, the live birth rate was significantly higher in the blastocyst group (P = 0.04). No significant differences were found between the cleavage-stage and blastocyst-stage groups in terms of implantation, clinical pregnancy, miscarriage and live birth rates. CONCLUSION: We do not recommend the use of the ZIFT procedure for patients with repeated implantation failures. It seems that replication of cleavage- or blastocyst-stage embryo transfer is more efficient and affordable.

Impact of PCOS on early embryo cleavage kinetics.

This study investigated whether polycystic ovary syndrome (PCOS) affected early embryo development assessed by time-lapse analysis of embryo kinetics from fertilization to the blastocyst stage. This was a prospective cohort study of two pronuclei (2PN) embryos from 25 hyperandrogenic PCOS patients (110 2PN embryos), 26 normoandrogenic PCOS patients (140 2PN embryos) and 20 healthy, regularly cycling women (controls, 97 2PN embryos). Patients underwent the same baseline evaluation and the same ovarian stimulation from April 2010 to February 2013. Oocytes were fertilized by intracytoplasmic sperm injection and incubated in an EmbryoScope with pictures taken every 20 min in seven focal planes. Time to 2PN breakdown, first cleavage and cleavage to 3, 4, 5, 6, 7 and 8 cells, morula and blastocyst (t2, t3, t4, t5, t6, t7, t8, t(M), t(B)) were annotated. Differences in embryo kinetics between groups were assessed by mixed modelling. Compared with controls, embryos from hyperandrogenic PCOS patients were significantly delayed at 2PN breakdown, t2, t3, t4 and t7 but not at t5, t6, t8, t(M) or t(B). Embryos from hyperandrogenic PCOS women had developed slower from fertilization to the 8-cell stage compared with embryos from controls.

Transfer of blastocysts with deviant morphological and morphokinetic parameters at early stages of in-vitro development: a case series.

Time-lapse imaging is increasingly applied as an adjunct to reproductive medicine. The gained information of the morphological and morphokinetic variables before the onset of transcription are supposed to be good predictors for the selection of the best embryo for transfer and are often seen in line with clinical outcomes. This retrospective case series investigated the outcome of transferred blastocysts that did not fulfil the proposed embryo scores at early cleavage or at later stages of development. The observations were made by time-lapse imaging. This study reports the birth of 16 healthy children after day-5 blastocyst transfer, of which at least one of the transferred embryos originated from deviant morphology and/or kinetic cleavage patterns. This case series suggests that some blastocysts derived from embryos with poor conventional morphological score and/or suboptimal morphokinetics can be successfully transferred and might result in live births. Such results might raise awareness that discarding embryos based only on early events is not a suitable approach to give patients the chance to conceive. In conclusion, to date only the transfer of viable embryos after culturing them until day 5 guarantees optimal embryo selection and helps to prevent embryo wastage.

Embryo quality but not pronuclear score is associated with clinical pregnancy following IVF.

PURPOSE: The association between pronuclear (PN) scoring of embryos from assisted reproductive technology (ART) and clinical pregnancy remains controversial. We hypothesized that embryos with PNs scored on the day of fertilization check offer better embryo selection on day 3 and higher CPR compared to non-PN scored embryos. METHODS: Patients (19-46 years) undergoing IVF/ICSI cycles at Montefiore's Institute for Reproductive Medicine and Health between January 2006 and December 2009 were included in our study. We analyzed fresh day 3 cycles only with autologous oocytes and partner's fresh sperm (n = 344). A total of 1,899 embryos were included. We compared CPR from non-PN scored embryos (Group 1, n = 835) with PN scored embryos (Group 2, n = 1,064). Composite scores by patient were developed based on embryo disposition. We also assessed traditional embryo grading derived from cell number, fragmentation and cell symmetry. Data analysis included chi square and t test to determine if PN scoring was associated with improved CPR, and to compare the additional variables. RESULTS: CPR between Group 1 and Group 2 were not different (p = 0.91). CPR was significantly associated with female age, number of mature oocytes retrieved, number of day 3 embryos and grade of embryos transferred on day 3 (p < 0.05). CONCLUSION: PN scoring was not associated with improved CPR in day 3 embryo transfers. Mean grade of transferred embryos continues to be a well-established, independent predictor of CPR. We conclude that further refinement of embryo grading by PN scoring is not beneficial.

Advanced scheduling for zygote intrafallopian transfer is possible via the use of a hormone replacement cycle for patients who have experienced repeated implantation failures.

PURPOSE: Zygote intrafallopian transfer (ZIFT) is an effective option for patients who have experienced repeated implantation failures (RIF) in assisted reproductive technology (ART) treatment. However, advance planning for the day of the operation can be problematic. Using a hormone replacement cycle (HRC) makes it possible to plan for the day of ZIFT. In the present study, we evaluated whether HRC-ZIFT is useful for RIF patients who have experienced difficulties obtaining morphologically good embryos in vitro. METHODS: A total of 55 patients with a history of five or more unsuccessful transfers received HRC-ZIFT between June 2008 and June 2013. The oocyte pick-ups were performed and the oocytes showing two pronuclei (2PN) were cryopreserved. After receiving more than five 2PN oocytes, the operation day was scheduled in advance, and as a consequence, a HRC was started and ZIFT was performed. The clinical outcomes were evaluated. RESULTS: The average age of the patients was 39.3 years, and the previous OPU and ET attempts numbered 7.5 and 6.9, respectively. The number of previously transferred embryos was 11.8, and the number of morphologically good embryos (MGEs) was only 1.2. The number of transferred 2PN oocytes was 6.7, and the subsequent pregnancy rate was 23.6 %. No ectopic or multiple pregnancies were observed, but there were 6 cases of miscarriage. CONCLUSION: Among RIF patients, in particular those who have difficulty obtaining MGEs in vitro, ZIFT might be a useful option. The HRC allows patients and medical staff to plan for the operation day in advance.

PROST: quantitative identification of spatially variable genes and domain detection in spatial transcriptomics.

Computational methods have been proposed to leverage spatially resolved transcriptomic data, pinpointing genes with spatial expression patterns and delineating tissue domains. However, existing approaches fall short in uniformly quantifying spatially variable genes (SVGs). Moreover, from a methodological viewpoint, while SVGs are naturally associated with depicting spatial domains, they are technically dissociated in most methods. Here, we present a framework (PROST) for the quantitative recognition of spatial transcriptomic patterns, consisting of (i) quantitatively characterizing spatial variations in gene expression patterns through the PROST Index; and (ii) unsupervised clustering of spatial domains via a self-attention mechanism. We demonstrate that PROST performs superior SVG identification and domain segmentation with various spatial resolutions, from multicellular to cellular levels. Importantly, PROST Index can be applied to prioritize spatial expression variations, facilitating the exploration of biological insights. Together, our study provides a flexible and robust framework for analyzing diverse spatial transcriptomic data.

Long-Term Reliability and Validity of the AO Spine PROST (Patient-Reported Outcome Spine Trauma).

STUDY DESIGN: Cross-sectional validation study. OBJECTIVE: The aim was to validate the AO Spine Patient-Reported Outcome Spine Trauma (PROST) at a minimum of 12 months posttrauma and to evaluate patient characteristics, types of spine fractures, and treatment strategies as determinants of AO Spine PROST scores. SUMMARY OF BACKGROUND DATA: The reliability and validity of the AO Spine PROST as a measure of health-related quality of life for more than 12 months after onset of spine trauma is unclear. MATERIALS AND METHODS: Patients with a traumatic spine injury were recruited from a level-1 trauma center. They were asked to complete the AO Spine PROST, EuroQoL 5D-5L (EQ-5D-5L), and either Oswestry disability index (ODI) or neck disability index (NDI) for concurrent validity. Internal consistency was assessed by calculating the Cronbach α and item-total correlation coefficients. Test-retest reliability was evaluated using intraclass correlation coefficients. Spearman correlation tests were performed for the AO Spine PROST in correlation with the EQ-5D-5L, and either ODI or NDI. Determinants for AO Spine PROST score were analyzed using multivariate regression models. RESULTS: A total of 175 patients participated in the cross-sectional arm and 49 in the test-retest arm of the study. Median duration of follow-up was 94.5 months. No floor or ceiling effects were seen. Internal consistency was excellent (α=0.98, item-total correlation coefficient: 0.73-0.91) as well as test-retest reliability (intraclass correlation coefficient=0.81). Satisfactory correlations were seen for the EQ-5D-5L (0.76; P <0.001), ODI (0.69; P <0.001), and NDI (0.68; P <0.001) with the AO Spine PROST. Multivariate linear regression models showed that having ≥1 comorbidities, duration of return to work within the range of 7 to 43 months and no return to work were significant independent determinants for a worse AO Spine PROST score. CONCLUSIONS: Very good long-term reliability and validity results were found for the AO Spine PROST.

Efficient reproduction of cynomolgus monkey using pronuclear embryo transfer technique.

One of the technical bottlenecks in producing nonhuman primate models is that current assisted reproductive techniques, such as in vitro culture and frozen conservation of multicell-stage embryos, often result in poor embryo quality and subsequently lead to low birth rates. We investigated whether pronuclear embryo transfer can be used as an effective means for improving pregnancy and live birth rates of nonhuman primates. We collected 174 metaphase II oocytes by laparoscopy from 22 superovulated mature females and then fertilized these eggs using either in vitro fertilization or intracytoplasmic sperm injection, resulting in a 33.3% and a 50% fertilization rate, respectively. These 66 fertilized pronuclear-stage embryos were then tubally transferred to 30 recipients and led to 7 births and 1 abortion. Importantly, we observed that the highest live birth rate of approximately 64% was obtained when the transfer of pronuclear embryos was performed in the presence of new corpus luteum in the ovary of recipients between 24 h and 36 h after estradiol peak. Therefore, our experiments demonstrate that by matching the critical time window in the recipient's reproductive cycle for achieving optimal embryo-uterine synchrony, pronuclear embryo transfer technology can significantly improve the pregnancy rate and live birth of healthy baby monkeys. This efficient method should be valuable to the systematic efforts in construction of various transgenic primate disease models.

Assisted reproductive technologies in Thailand: 2001-2007 results generated from the ART Registry, Royal Thai College of Obstetricians and Gynaecologists.

AIM: To present the results of assisted reproductive technology (ART) performed in Thailand during 2001-2007. METHODS: All licensed ART centers are obliged to submit annual reports on the number of patients, cycles, ART techniques and treatment outcomes to the Reproductive Medicine Subcommittee of the Royal Thai College of Obstetricians and Gynaecologists. Data from all centers were aggregated and analyzed retrospectively. RESULTS: Cycles were categorized into fresh and frozen/thawed embryo transfer (FET) cycles. Initiated cycles in the first category for 2001 to 2007 were 2183, 2112, 2780, 2717, 3458, 3579 and 4288, respectively. FET cycles during the same period were 467, 558, 733, 768, 1136, 1210 and 1473, respectively. The average pregnancy rate for in vitro fertilization (IVF) was 28.9% per retrieval (range, 26-32.3%) or 33.8% per transfer (range, 30.7-38.6%). Multiple pregnancies (of which 89.3% were twins) from all treatment procedures during this period were 11.4% (range, 9.2-14.5%). A congenital abnormality was reported in 0.56% of live births. The number of embryos per transfer in IVF decreased from 4.1 to 2.9, with no drop in pregnancy rates. Oocyte insemination by intracytoplasmic sperm injection (ICSI) was utilized more often than standard IVF, while gamete intrafallopian transfer and zygote intrafallopian transfer were almost completely replaced by IVF/ICSI. There was a significant difference in pregnancy rates (P < 0.01) when clinics were classified by cycle volumes (<100, 100-400 and >400 cycles/year). CONCLUSIONS: Despite many limitations, the data provided in this report will help patients, clinicians and policy makers understand the current situation of ART practice in Thailand.

Office microlaparoscopic intrafallopian transfer of day one zygote versus day three embryo transfer after previous failed ICSI trials.

The objective of the study was to investigate whether transferring zygotes on day 1 would result in similar pregnancy rates compared to transferring cleavage stage embryos on day 3 in a prospective randomized trial, using the office microlaparoscopic procedure. Patients undergoing IVF/ICSI treatments were randomized to either day 1 or day 3 transfers after previous failed ICSI trials due to failed implantation. The primary outcome measure was pregnancy rate. Pregnancy rates were higher in day 3 group (55/131, 42%) when compared to day 1 (34/123, 28%, P = 0.024). Similarly, implantation rates were higher in day 3 group (P = 0.03). There were more cycles with cryopreservation in the day 1 group (P < 0.001). Embryo quality on day 3 was similar between pattern 0 and non-pattern 0 zygotes. Day 3 embryo transfers result in better pregnancy and implantation rates compared to day 1 zygote transfers.

Obstetric and neonatal outcomes after the transfer of vitrified-warmed blastocysts developing from nonpronuclear and monopronuclear zygotes: a retrospective cohort study.

OBJECTIVE: To evaluate the obstetric and neonatal outcomes after the transfer of vitrified-warmed single blastocysts developing from nonpronuclear (0PN) and monopronuclear (1PN) zygotes. DESIGN: Cohort study. SETTING: Affiliated hospital. PATIENT(S): This study was a retrospective analysis of 435 0PN and 281 1PN vitrified-warmed single blastocyst transfers, and 151 0PN and 75 1PN singletons, compared with 13,167 two-pronuclear (2PN) vitrified-warmed single blastocyst transfers and 4,559 2PN singletons, respectively. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Pregnancy rate (PR), abortion rate (AR), live birth rate (LBR), and singleton birthweight were the primary outcome measures. RESULT(S): PR, AR, and LBR were similar when compared between the 0PN and 2PN groups after vitrified-warmed blastocyst transfer. However, the 0PN group had a higher birthweights, higher z scores, and a greater proportion of very large for gestational age newborns. When comparing the 1PN and 2PN groups, we found that the PR was similar whereas the AR was higher and the LBR was lower. No differences were detected in the other neonatal outcomes. CONCLUSION(S): The results of the present study show that the transfer of 2PN blastocysts should be prioritized because of a higher AR and a lower LBR after 1PN blastocyst transfers and a higher birthweight after 0PN blastocyst transfers when compared with 2PN blastocyst transfers. Our data indicate the need for concern about the safety of 1PN and 0PN embryo transfers.

Analysis of pronuclear zygote configurations in 459 clinical pregnancies obtained with assisted reproductive technique procedures.

BACKGROUND: Embryos selection is crucial to maintain high performance in terms of pregnancy rate, reducing the risk of multiple pregnancy during IVF. Pronuclear and nucleolar characteristics have been proposed as an indicator of embryo development and chromosomal complement in humans, providing information about embryo viability. METHODS: To correlate the zygote-score with the maternal age and the outcome of pregnancy, we analyzed the pronuclear and nucleolar morphology, the polar body alignment and the zygote configuration in 459 clinical pregnancies obtained by IVF and ICSI in our public clinic in Reggio Emilia, Italy. We derived odds ratios (OR) and Corenfield's 95% confidence intervals (CI). Continuous variables were compared with Student's t-test; P lower than .05 was considered statistically significant. RESULTS: We observed a significant increase of "A" pronuclear morphology configuration in 38-41 years old patients in comparison to that lower than or equal to 32 years old and a significant decrease of "B" configuration in 38-41 years old patients in comparison to that lower than or equal to 32 and in comparison to that of 33-37 years old. Related to maternal age we found no significant differences in P1 and in P2 configuration. We found no correlation between zygote-score, embryo cleavage and embryo quality. CONCLUSIONS: Our results confirm the limited clinical significance of zygote-score suggesting that it can not be associated with maternal age, embryo cleavage and embryo quality. The evaluation of embryo quality based on morphological parameters is probably more predictive than zygote-score.

Freeze-all: enhanced outcomes with cryopreservation at the blastocyst stage versus pronuclear stage using slow-freeze techniques.

This retrospective cohort study compared outcomes from transfer of embryos cryopreserved at the pronuclear versus blastocyst stage following 'freeze-all' IVF cycles without fresh transfer for 87 consecutive IVF patients <40 years, who underwent cryopreservation of all viable embryos followed by at least one subsequent frozen embryo transfer (FET) between January 2003 and July 2007. Cryopreservation of all embryos from one oocyte retrieval was performed at either the pronuclear (1.5 mol/l propanediol and 0.1 mol/l sucrose) (group A) or blastocyst (10% glycerol) (group B) stage. Main outcome measures included survival, live birth and implantation rates. A total of 110 FET cycles were analysed. Live birth and implantation rates observed after the first FET were significantly higher (P=0.025 and P=0.002) in group B (67.7% and 40.8%) than in group A (41.1% and 21.5%) despite a higher survival rate in group A. After two FET cycles, 32.1% of group A had not conceived despite thaw of all available embryos, compared with 6.5% of group B. When freeze-all is necessary, blastocyst cryopreservation leads to higher implantation and live birth rates compared with pronuclear-stage cryopreservation despite lower survival rates. Prolonged embryo culture may allow for more optimal embryo selection.

Comparison of different cryopreservation techniques: higher survival and implantation rate of frozen-thawed mouse pronuclear embryos in the presence of beta-mercaptoethanol in post-thaw culture.

The objective of this study was to investigate the effects of beta-mercaptoethanol (ß-ME) on post-thaw embryo developmental competence and implantation rate of mouse pronuclear (PN) embryos that were cryopreserved after slow freezing, solid surface vitrification (SSV) or open-pulled straw (OPS) vitrification methods. Mouse PN embryos were cryopreserved by using slow freezing, SSV and OPS methods. After cryopreservation, freeze-thawed PN embryos were cultured up to blastocyst stage in a defined medium supplemented without or with 50 µM ß-ME. The blastocyst formation rate of embryos that were cryopreserved by slow freezing method (40.0%) or vitrified by OPS method (18.3%) were lower than those vitrified by SSV method (55.6%) and fresh embryos (61.9%) in the absence of 50 ß-ME in the culture media (p < 0.05). The blastocyst formation rate of embryos that were cryopreserved by slow freezing method (53.1%) or by OPS method (41.9%) were lower than those vitrified by SSV method (79.5%) and that of fresh (85.7%) in the presence of ß-ME in the culture media (p < 0.05). The embryos transfer results revealed that the implantation rate of blastocyst derived from mouse PN embryos vitrified by SSV method (31.9% vs 51.2%) was similar to that of the control (39.0% vs 52.5%), but higher than those cryopreserved by slow freezing (28.2% vs 52.0%) and by OPS method (0.0% vs 51.2%) (p < 0.05). In conclusion, supplementation of ß-ME in an in vitro culture medium was shown to increase survival of embryo development and implantation rate of frozen-thawed mouse PN embryos after different cryopreservation protocols.