Molecular Physiology of Freeze Tolerance in Vertebrates.

Freeze tolerance is an amazing winter survival strategy used by various amphibians and reptiles living in seasonally cold environments. These animals may spend weeks or months with up to ∼65% of their total body water frozen as extracellular ice and no physiological vital signs, and yet after thawing they return to normal life within a few hours. Two main principles of animal freeze tolerance have received much attention: the production of high concentrations of organic osmolytes (glucose, glycerol, urea among amphibians) that protect the intracellular environment, and the control of ice within the body (the first putative ice-binding protein in a frog was recently identified), but many other strategies of biochemical adaptation also contribute to freezing survival. Discussed herein are recent advances in our understanding of amphibian and reptile freeze tolerance with a focus on cell preservation strategies (chaperones, antioxidants, damage defense mechanisms), membrane transporters for water and cryoprotectants, energy metabolism, gene/protein adaptations, and the regulatory control of freeze-responsive hypometabolism at multiple levels (epigenetic regulation of DNA, microRNA action, cell signaling and transcription factor regulation, cell cycle control, and anti-apoptosis). All are providing a much more complete picture of life in the frozen state.

Does dual oocyte retrieval with continuous FSH administration increase the number of mature oocytes in low responders? An open-label randomized controlled trial.

STUDY QUESTION: Is there an increase in the total number of metaphase II (MII) oocytes between a conventional ovarian stimulation (OS) and a double uninterrupted stimulation? SUMMARY ANSWER: There is no increase in the total number of MII oocytes when comparing one conventional OS to a continuous stimulation with double oocyte aspiration. WHAT IS KNOWN ALREADY: Based on the concept of multiple follicular waves, the combination of two stimulations in the same ovarian cycle has gained interest in patients with a low ovarian reserve. This so-called dual stimulation approach is usually characterized by a discontinuation of FSH administration for ∼5 days and appears to have a favourable impact on the number of retrieved oocytes without affecting the embryo quality or ploidy status. The outcomes of dual uninterrupted OS have not yet been studied. STUDY DESIGN, SIZE, DURATION: This was an open-label randomized controlled trial (RCT) with superiority design, performed in a single tertiary centre. Subjects were randomized with a 1:1 allocation into two groups between October 2019 and September 2021. All patients underwent a conventional stimulation with recombinant FSH. When two or more follicles of 17 mm were present, the final inclusion criterion was assessed; randomization occurred only in the presence of ≤9 follicles of ≥11 mm. In Group A, ovulation was triggered with hCG, and oocyte retrieval (OR) was performed 34-36 h later, followed by a fresh single or double embryo transfer (SET or DET) on Day 3/5. In Group B, ovulation was triggered with GnRH agonist, followed by another OS, without discontinuation of the FSH administration. In the presence of one or more follicles of ≥17 mm, the second stimulation was completed with hCG. A freeze-all strategy (Day 3/5) was applied for both retrievals, followed by transfer of one or two embryos in an artificially prepared frozen-thawed cycle. In the absence of one or more follicles of ≥17 mm after 13 additional days of stimulation, the second cycle was cancelled. All ORs were executed by a senior fertility specialist who was blinded for the first treatment, and all follicles >10 mm were aspirated, according to routine clinical practice. The primary outcome was the total number of MII oocytes. Patients were followed up until all embryos were transferred, or until live birth was achieved. Other secondary outcomes included the number of cumulus-oocyte complexes (COCs), the number of good quality embryos (Day 3/5), the ongoing pregnancy rate, and gonadotropin consumption. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients between 25 and 40 years old, with an anti-Müllerian hormone level of ≤1.5 ng/ml, antral follicle count of ≤6, or ≤5 oocytes after a previous stimulation, were included. At the start, 70 patients were eligible for participation in the trial, of whom 48 patients fulfilled the final inclusion criterium and were randomized. After drop-out of two patients, 23 patients were randomized to a single round of OS (Group A), and 23 patients were randomized to two uninterrupted rounds of OS (Group B). MAIN RESULTS AND THE ROLE OF CHANCE: Baseline characteristics were similar between both groups. The cumulative number of COCs and MII oocytes after completion of the second OR was similar in Group A and Group B [5.3 ± 2.7 versus 5.3 ± 3.0 (P = 0.95); 4.1 ± 2.4 versus 4.3 ± 2.7 (P = 0.77)]. Likewise, a comparable number of excellent and good quality embryos was available on Day 3 (3.0 ± 2.0 versus 2.7 ± 2.0; P = 0.63). In Group B, the cancellation rate due to insufficient response to the second round of stimulation was 39.1% (9/23). When focusing on the first stimulation in both groups, there were no significant differences regarding basal FSH, gonadotropin consumption, and the number of preovulatory follicles. After the first OR, the mean number of COC and MII oocytes was significantly higher in Group A (who had hCG triggering), compared to Group B (who had GnRH agonist triggering) [5.3 ± 2.7 versus 3.3 ± 2.2; difference 95% CI (0.54 to 3.45), P = 0.004 and 4.1 ± 2.4 versus 3.0 ± 2.2; difference 95% CI (-0.15 to 2.6), P = 0.05, respectively]. Likewise, the number of excellent and good quality embryos on Day 3 was significantly higher (3.0 ± 2.0 versus 1.9 ± 1.7; P = 0.02) in Group A. LIMITATIONS, REASONS FOR CAUTION: This study was powered to demonstrate superiority for the number of MII oocytes after dual stimulation. Investigating the impact of dual stimulation on pregnancy rates would have required a larger sample size. Furthermore, the heterogeneity in embryo vitrification and transfer policies precluded a correct comparison of embryologic outcomes between both groups. WIDER IMPLICATIONS OF THE FINDINGS: This is the first RCT investigating the role of continuous stimulation with double aspiration in low responders. Our results show no statistically significant differences in the cumulative number of MII oocytes between one conventional stimulation with fresh ET and two consecutive stimulations with a freeze-only approach. Furthermore, the observed suboptimal oocyte yield after agonist ovulation triggering in low responders in the dual uninterrupted OS group is a reason for concern and further scrutiny, given that previous RCTs have shown similar outcomes in normal and high responders after hCG and GnRH agonist triggers. STUDY FUNDING/COMPETING INTEREST(S): This work was supported in part by a research grant from Organon. H.T. received honoraria for lectures and presentations from Abbott, Cooper Surgical, Gedeon-Richter, Cook, Goodlife, and Ferring. L.B. received fees for lectures from Merck & Organon and support for attending ESHRE 2023. M.D.V. reports fees for lectures from Ferring, Merck, Organon, IBSA, Gedeon Richter, and Cooper Surgical and support for attending ASRM 2023. S.M. received honoraria for lectures and presentations from Abbott, Cooper Surgical, Gedeon-Richter, IBSA, and Merck. C.B. was on the Advisory board and received consulting fees from Theramex and received honoraria for lectures and presentations from Abbott, Ferring, Gedeon-Richter, IBSA, and Merck. TRIAL REGISTRATION NUMBER: NCT03846544. TRIAL REGISTRATION DATE: 19 February 2019. DATE OF FIRST PATIENT'S ENROLMENT: 28 October 2019.

Follitropin delta combined with menotropin in patients at risk for poor ovarian response during in vitro fertilization cycles: a prospective controlled clinical study.

BACKGROUND: The maximum daily dose of follitropin delta for ovarian stimulation in the first in vitro fertilization cycle is 12 µg (180 IU), according to the algorithm developed by the manufacturer, and based on patient's ovarian reserve and weight. This study aimed to assess whether 150 IU of menotropin combined with follitropin delta improves the response to stimulation in women with serum antimullerian hormone levels less than 2.1 ng/mL. METHODS: This study involved a prospective intervention group of 44 women who received 12 µg of follitropin delta combined with 150 IU of menotropin from the beginning of stimulation and a retrospective control group of 297 women who received 12 µg of follitropin delta alone during the phase 3 study of this drug. The inclusion and exclusion criteria and other treatment and follow-up protocols in the two groups were similar. The pituitary suppression was achieved by administering a gonadotropin-releasing hormone (GnRH) antagonist. Ovulation triggering with human chorionic gonadotropin or GnRH agonist and the option of transferring fresh embryos or using freeze-all strategy were made according to the risk of developing ovarian hyperstimulation syndrome. RESULTS: Women who received follitropin delta combined with menotropin had higher estradiol levels on trigger day (2150 pg/mL vs. 1373 pg/mL, p < 0.001), more blastocysts (3.1 vs. 2.4, p = 0.003) and more top-quality blastocysts (1.8 vs. 1.3, p = 0.017). No difference was observed in pregnancy, implantation, miscarriage, and live birth rates after the first embryo transfer. The incidence of ovarian hyperstimulation syndrome did not differ between the groups. However, preventive measures for the syndrome were more frequent in the group using both drugs than in the control group (13.6% vs. 0.6%, p < 0.001). CONCLUSIONS: In women with serum antimullerian hormone levels less than 2.1 ng/mL, the administration of 150 IU of menotropin combined with 12 µg of follitropin delta improved the ovarian response, making it a valid therapeutic option in situations where ovulation triggering with a GnRH agonist and freeze-all embryos strategy can be used routinely. TRIAL REGISTRATION: U1111-1247-3260 (Brazilian Register of Clinical Trials, available at https://ensaiosclinicos.gov.br/rg/RBR-2kmyfm ).

Fresh or frozen day 6 blastocyst transfer: is there still a question?

BACKGROUND: The Live Birth Rate (LBR) after day 5 (D5) blastocyst transfer is significantly higher than that with D6 embryos in both fresh and frozen-vitrified embryo transfer cycles, according to the most recently published meta-analyses. Therefore, for women obtaining only D6 blastocysts, the chances of pregnancy may be lower but nonetheless sufficient to warrant transferring such embryos. The best strategy for transfer (i.e., in fresh versus frozen cycles) remains unclear and there is a paucity of data on this subject. METHODS: A total of 896 couples with D6 single blastocyst transfers were retrospectively analyzed: patients receiving a fresh D6 embryo transfer (Fresh D6 transfer group, n = 109) versus those receiving a frozen-thawed D6 embryo transfer (Frozen D6 transfer group, n = 787). A subgroup comprising a freeze-all cycle without any previous fresh or frozen D5 embryo transfers (Elective frozen D6, n = 77) was considered and also compared with the Fresh D6 transfer group. We compared LBR between these two groups. Correlation between D6 blastocyst morphology according to Gardner's classification and live birth occurrence was also evaluated. Statistical analysis was carried out using univariate and multivariate logistic regression models. RESULTS: The LBR was significantly lower after a fresh D6 blastocyst transfer compared to the LBR with a frozen-thawed D6 blastocyst transfer [5.5% (6/109) vs. 12.5% (98/787), p = 0.034]. Comparison between LBR after Elective frozen D6 group to the Fresh D6 blastocyst transfers confirmed the superiority of frozen D6 blastocyst transfers. Statistical analysis of the blastocyst morphology parameters showed that both trophectoderm (TE) and inner cell mass (ICM) grades were significantly associated with the LBR after D6 embryo transfer (p < 0.001, p = 0.037). Multiple logistic regression revealed that frozen D6 thawed transfer was independently associated with a higher LBR compared with fresh D6 transfer (OR = 2.54; 95% CI: [1.05-6.17]; p = 0.038). Our results also show that transferring a good or top-quality D6 blastocyst increased the chances of a live birth by more than threefold. CONCLUSIONS: Our results indicate that transferring D6 blastocysts in frozen cycles improves the LBR, making it the best embryo transfer strategy for these slow-growing embryos. CLINICAL TRIAL NUMBER: Not applicable.

Avoiding weekend frozen embryo transfer in modified natural cycles: is it possible?

In this era of the freeze-all strategy, the prevalence of frozen embryo transfer (FET) cycles is increasing rapidly. Although still quite often used, the hormone replacement therapy cycle to prepare a FET should now belong to the past, unless strictly necessary. This raises questions about possible flexible protocols for the preparation of an FET cycle in a (modified) natural cycle. In this viewpoint, an overview of the different options is discussed, stressing the importance of the corpus luteum.

GnRH agonist trigger in poor prognosis patients undergoing a multicycle approach through DuoStim or consecutive stimulations: a SWOT analysis.

PURPOSE OF REVIEW: Identify the most recent and significant evidence regarding the ovulation trigger within the framework of a multicycle approach through DuoStim, providing valuable insights for improving treatment strategies in patients with a poor prognosis. RECENT FINDINGS: The trigger method plays a pivotal role in optimizing in-vitro fertilization (IVF) stimulation, influencing oocyte retrieval and maturation rates, as well as follicle recruitment in consecutive ovarian stimulations such as double stimulation. Decision-making involves multiple factors and, while guidelines exist for conventional stimulation, specific recommendations for the multicycle approach are not well established. SUMMARY: The different methods for inducing oocyte maturation underscore the need for personalization of IVF protocols. The GnRH agonist trigger induces rapid luteolysis and establishes favorable hormonal conditions that do not adversely affect the recruitment of consecutive follicular waves in the context of DuoStim. It serves as a valid alternative to hCG in freeze-all cycles. This strategy might enhance the safety and flexibility of ovarian stimulations with no impact on oocyte competence and IVF efficacy.

Higher pre-pregnancy body mass index was associated with adverse pregnancy and perinatal outcomes in women with polycystic ovary syndrome after a freeze-all strategy: A historical cohort study.

INTRODUCTION: Previous studies have demonstrated that abnormal body mass index (BMI) is associated with adverse pregnancy outcomes in frozen-thawed embryo transfer cycles. However, the relationship between BMI and pregnancy and perinatal outcomes in patients with polycystic ovary syndrome (PCOS) remains unclear. Furthermore, whether a diagnosis of PCOS could result in adverse pregnancy and perinatal outcomes in women with different BMIs remains unknown. MATERIAL AND METHODS: A historical cohort study included 1667 women with PCOS and 12 256 women without PCOS after a freeze-all policy between January 2016 and December 2020. The outcomes encompassed both pregnancy and perinatal outcomes. Multivariate logistic regression analysis and restricted cubic spline models were performed to eliminate confounding factors when investigating the relationship between BMI and different outcomes. RESULTS: After controlling for covariates, pregnancy outcomes were comparable between underweight women with PCOS and normal weight women with PCOS. However, overweight patients had a lower clinical pregnancy rate and an overall live birth rate. Furthermore, patients with obesity had a lower rate of multiple pregnancies but a higher rate of biochemical pregnancy than in the normal BMI group. Additionally, the restricted cubic spline models showed that as maternal BMI increased to 32 kg/m2, the clinical pregnancy rate and live birth rate after blastocyst transfer decreased, but the risks of preterm birth, gestational diabetes mellitus, macrosomia, large-for-gestational age (LGA) and very LGA increased in patients with PCOS after a freeze-all strategy. Moreover, a diagnosis of PCOS resulted in a higher clinical pregnancy rate and live birth rate and a higher risk of small-for-gestational age in the normal weight group. However, women with PCOS in the overweight group exhibited higher risks of very preterm birth and gestational diabetes mellitus compared with women without PCOS. CONCLUSIONS: This study showed that a higher BMI had a detrimental impact on the pregnancy and perinatal outcomes of PCOS patients undergoing a freeze-all strategy. However, it was only statistically significant in the overweight group. A diagnosis of PCOS had a higher clinical pregnancy rate and live birth rate in normal weight women but higher risks of perinatal complications in normal weight and overweight women.

Comparison of Clinical Outcomes in the Slow-Developing Blastocysts With or Without Preimplantation Genetic Testing-Aneuploidy on Day 6 in the Frozen-Thawed Cycle.

OBJECTIVES: This study investigated the potential of the slow-developing blastocysts using preimplantation genetic testing-aneuploidy (PGT-A) in patients undergoing frozen-thawed embryo transfer, stratified by age. METHODS: A retrospective analysis was performed including a total of 743 cycles, the first frozen embryo transfer (FET) cycle with single embryo transfer, who underwent treatment between January 2020 and July 2023 in a single fertility centre, Gangnam CHA Fertility Center. A total of 743 cycles, in which we performed intracellular sperm injection and freeze-all strategy, from 743 patients were included. The patient group was divided into 4 groups as follows: group 1 (G1), 208 FET on day 5; group 2 (G2), 177 FET with PGT-A on day 5; group 3 (G3), 220 FET on day 6; group 4 (G4), 138 FET with PGT-A on day 6. We also divided into 2 groups-under 35 years of age and over 35 years of age-and performed the analysis separately for each group. RESULTS: In the under 35 years of age group, there were no significant differences in clinical pregnancy and miscarriage rates in G1 and G2 (67.2% vs. 63.8%, not statistically significantly different). Also, G4 had a higher clinical pregnancy rate than G3, but it was not significant (51.8% vs. 54.7%, not statistically significantly different). In the 35 years or older group, G2 had higher pregnancy rates than G1 and lower miscarriage rates (clinical pregnancy rate: 43.3% vs. 67.7%, P = 0.001, miscarriage rate: 22.5% vs. 3.4%, P = 0.001). In addition, G4 had a higher pregnancy rate than G3 and a lower miscarriage rate (clinical pregnancy rate: 31.8% vs. 46.9%, P = 0.003, miscarriage rate: 22.9% vs. 2.2%, P = 0.023). CONCLUSIONS: In the under-35-year-old group, PGT-A on day 5 and day 6 showed a high pregnancy rate and a low miscarriage rate. Therefore, using PGT-A seems advantageous for patients of an advanced maternal age.

Can serum progesterone concentration direct a fresh or freeze-all transfer strategy in the first in vitro fertilisation cycle?

PURPOSE: To examine the interaction between serum progesterone concentration on the trigger day and choice of freeze-all and fresh transfer strategies on live birth in an unselected population as well as in patients over 35 years old. METHODS: We performed a retrospective cohort study of 26,661 patients commencing their first IVF cycle in a large fertility centre between 2015 and 2019, including 4687 patients over 35 years old. We performed a multivariable fractional polynomial interaction analysis within a logistic regression model to investigate the interaction between serum progesterone concentration and the choice of freeze-all or fresh transfer strategy following the first transfer. RESULTS: 15,539 patients underwent a fresh embryo transfer and 11,122 underwent a freeze-all strategy in their first IVF cycle. The freeze-all group had a higher live birth rate compared to the fresh group (43.9% vs 40.3%). After adjusting for confounding factors, there was a positive interaction between serum progesterone concentrations and the choice of a freeze-all versus fresh embryo transfer on live birth (p for interaction 0.0001), with a larger magnitude of effect when progesterone concentration was higher. Such an interaction was also observed in patients over 35 years old (p for interaction 0.01), but the treatment effect curve over progesterone concentrations was almost flat. CONCLUSIONS: In an unselected population, frozen transfer is associated with greater chances of live birth, especially in patients with higher serum progesterone concentration. In patients over 35 years old, the benefit of a freeze-all policy appears small across all serum progesterone concentrations.

Effect of GnRH agonist trigger with or without low-dose hCG on reproductive outcomes for PCOS women with freeze-all strategy: a propensity score matching study.

PURPOSE: This study aimed to compare the effect of gonadotropin-releasing hormone agonist (GnRHa) trigger alone versus dual trigger comprising GnRHa and low-dose human chorionic gonadotropin (hCG) on reproductive outcomes in patients with polycystic ovary syndrome (PCOS) who received the freeze-all strategy. METHODS: A total of 615 cycles were included in this retrospective cohort study. Propensity score matching (PSM) was performed to control potential confounding factors between GnRHa-trigger group (0.2 mg GnRHa) and dual-trigger group (0.2 mg GnRHa plus 1000/2000 IU hCG) in a 1:1 ratio. Multivariate logistic regression was applied to estimate the association between trigger methods and reproductive outcomes. RESULTS: After PSM, patients with dual trigger (n = 176) had more oocytes retrieved, mature oocytes, and 2PN embryos compared to that with GnRHa trigger alone. However, the oocytes maturation rate, normal fertilization rate, and frozen embryos between the two groups were not statistically different. The incidence of ovarian hyperstimulation syndrome (OHSS) (14.8% vs. 2.8%, P < 0.001) and moderate/severe OHSS (11.4% vs. 1.7%, P < 0.001) were significantly higher in dual-trigger group than in GnRHa-alone group. Logistic regression analysis showed the adjusted odds ratio of dual trigger was 5.971 (95% confidence interval 2.201-16.198, P < 0.001) for OHSS. The pregnancy and single neonatal outcomes were comparable between the two groups (P > 0.05). CONCLUSION: For PCOS women with freeze-all strategy, GnRHa trigger alone decreased the risk of OHSS without damaging oocyte maturation and achieved satisfactory pregnancy outcomes.

Influence of nano-formulations of clove bud (Syzygium aromaticum) extract on freezing ability, antioxidant capacity, caspase-3 activity, acrosome reaction and fertility of frozen rabbit semen.

The current study aimed to investigate the impact of nano-formulations of clove bud ethanolic extract (CBENF) in the extender on sperm characteristics, antioxidant capacity, oxidative biomarkers, enzymatic activity, apoptosis and fertility of post-thawed rabbit semen. Twelve mature male rabbits semen samples were pooled and cryopreserved in a Tris-egg yolk-based extender containing varying concentrations of CBENF (0, 25, 50, 75 and 100 µg/mL). After the equilibration and freezing-thawing process, CBENF (100 µg /mL) significantly enhanced progressive motility, viability and membrane integrity. Conversely, sperm abnormality was significantly reduced by CBENF supplementation. Total antioxidant capacity was increased in the post-thawed sperm medium, while nitric oxide and malondialdehyde were decreased in all CBENF concentrations. The lactic dehydrogenase and caspase-3 activities were decreased, whereas the number of live spermatozoa with an intact acrosome was increased in all CBENF concentrations. Conception rate and litter size per doe were higher in doe rabbits inseminated with semen supplemented with 100 µg CBENF/mL than un-supplemented group (76% vs. 52% and 8.4 vs. 7.7/doe), with no statistical differences. These findings suggest that supplementing rabbit extenders with 100 µg of CBENF/mL could be an effective strategy for enhancing freeze-thawing rabbit sperm attributes and fertility.

Bioactive Potential of Carrot-Based Products Enriched with Lactobacillus plantarum.

The primary goal of this study was to generate different kinds of functional products based on carrots that were supplemented with lactic acid bacteria. The fact that carrots (Daucus carota sp.) rank among the most popular vegetables in our country led to the convergence of the research aim. Their abundance of bioactive compounds, primarily polyphenols, flavonoids, and carotenoids, offers numerous health benefits. Among the obtained products, the freeze-dried carrot powder (FDCP) variation presented the highest concentrations of total carotenoids (TCs) and ß-carotene (BC) of 26.977 ± 0.13 mg/g DW and 22.075 ± 0.14 mg/g DW, respectively. The amount of total carotenoids and ß-carotene significantly increased with the addition of the selected lactic acid bacteria (LAB) for most of the samples. In addition, a slight increase in the antioxidant activity compared with the control sample for the FDCP variant, with the highest value of 91.74%, was observed in these functional food products. The content of polyphenolic compounds varied from 0.044 to 0.091 mg/g DW, while the content of total flavonoids varied from 0.03 to 0.66 mg/g DW. The processing method had an impact on the population of L. plantarum that survived, as indicated by the viability of bacterial cells in all the analyzed products. The chromatographic analysis through UHPLC-MS/MS further confirmed the abundance of the bioactive compounds and their corresponding derivatives by revealing 19 different compounds. The digestibility study indicated that carotenoid compounds from carrots followed a rather controlled release. The carrot-based products enriched with Lactobacillus plantarum can be considered newly functional developed products based on their high content of biologically active compounds with beneficial effects upon the human body. Furthermore, these types of products could represent innovative products for every related industry such as the food, pharmaceutical, and cosmeceutical industries, thus converging a new strategy to improve the health of consumers or patients.

The CombE-IDMS Assay as an Alternate Potency Method for Adjuvanted Quadrivalent Influenza Vaccines.

The potency of all currently licensed inactivated influenza viral vaccines is assayed by the single radial immunodiffusion (SRID) method. SRID relies upon antisera and reference antigen reagents which are produced, standardized, and distributed in the mass quantities needed for vaccine manufacturers only after a significant amount of time has elapsed from the seasonal strain recommendations issued by the WHO; this time delay is exacerbated under conditions of an emerging pandemic. Previously, the limited trypsin digestion isotope dilution mass spectrometry (LTD-IDMS) method, which does not require antisera or reference antigens, demonstrated comparable quantitation of immunologically active hemagglutinin, the primary viral antigen, to SRID in stressed vaccine materials. Here, we demonstrate a streamlined improvement to the LTD-IDMS method by eliminating the need for its precipitation and washing steps, saving time and labor in the sample preparation process while paving the way for plate-based high-throughput analysis. This is accomplished using dissimilar proteases in the pretreatment (a combination of chymotrypsin and elastase) and analytical (trypsin) digestion steps so that any pretreatment digests will not cause interference while monitoring analytical tryptic digests by IDMS. The combination of enzymes (CombE)-IDMS method is tested alongside LTD-IDMS and SRID for the first time on MF59 adjuvanted seasonal cell-based quadrivalent influenza vaccines (aQIVc) under stressed conditions of heating, oxidation, lowered and elevated pH, and freeze-thaw. Overall, a correlation in the degradation trend is observed between CombE-IDMS and SRID in the four strains of the quadrivalent formulation, highlighting the method's stability indicating capability as a rapid alternate potency assay in a highly complex formulation of aQIVc.

Psychosocial wellbeing shortly after allocation to a freeze-all strategy compared with a fresh transfer strategy in women and men: a sub-study of a randomized controlled trial.

STUDY QUESTION: Is the psychosocial wellbeing affected in women and men shortly after allocation to a freeze-all strategy with postponement of embryo transfer compared to a fresh transfer strategy? SUMMARY ANSWER: In general, psychosocial wellbeing (i.e. emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit) was similar in women and men allocated to a freeze-all versus those allocated to a fresh-transfer strategy 6 days after disclosure of treatment strategy (i.e. 4 days after oocyte retrieval), although women in the freeze-all group reported a slightly higher degree of depressive symptoms and mood swings compared to women in the fresh transfer group. WHAT IS KNOWN ALREADY: The use of a freeze-all strategy, i.e. freezing of the entire embryo cohort followed by elective frozen embryo transfer in subsequent cycles has increased steadily over the past decade in assisted reproductive technology (ART). This strategy essentially eliminates the risk of ovarian hyperstimulation syndrome and has proven beneficial regarding some reproductive outcomes in subgroups of women. However, patients experience a longer time interval between oocyte retrieval and embryo transfer, hence a longer time to pregnancy, possibly adding additional stress to the ART treatment. So far, little focus has been on the possible psychosocial strains caused by postponement of embryo transfer. STUDY DESIGN, SIZE, DURATION: This is a self-reported questionnaire based sub-study of a multicentre randomized controlled trial (RCT) including 460 women and 396 male partners initiating their first, second, or third treatment cycle of invitro fertilisation or intracytoplasmic sperm injection (ICSI) from May 2016 to September 2018. This sub-study was included in the primary project protocol and project plan for the RCT, as psychosocial wellbeing was considered a secondary outcome. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women from eight public fertility clinics in Denmark and Sweden and one private clinic in Spain were randomized in a 1:1 ratio on the day of inclusion (menstrual cycle day 2 or 3) to either a freeze-all strategy with postponement of embryo transfer to a subsequent modified natural menstrual cycle or a fresh transfer strategy with embryo transfer in the hormone stimulated cycle. Treatment allocation was blinded until the day of the ovulation trigger. Women and their male partners were asked to complete a validated self-reported questionnaire 6 days after unblinding of treatment group allocation, corresponding to 4 days after oocyte retrieval, investigating their psychosocial wellbeing related to the treatment defined as emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit. The questionnaire included items from the Copenhagen Multi-Centre Psychosocial Infertility (COMPI) Fertility Problem Stress Scales and the COMPI Marital Benefit Measure. MAIN RESULTS AND THE ROLE OF CHANCE: Baseline characteristics were comparable between the two groups for both women and men. In total, response rates were 90.7% for women and 90.2% for men. In the freeze-all group, 207 women and 179 men completed the questionnaire compared with 204 women and 178 men in the fresh transfer group. Men in the two treatment groups did not differ in any of the explored aspects of psychosocial wellbeing (i.e. emotional reactions to the treatment, quality-of-life, infertility-related stress, and marital benefit) 6 days after disclosure of treatment strategy. Women in the freeze-all group reported a slightly higher degree of depressive symptoms (P = 0.045) and mood swings (P = 0.001) (i.e. variables included in 'emotional reactions to treatment') compared to women in the fresh transfer group. When adjusted for multiple testing, depressive symptoms were no longer significantly different between the two groups. No additional differences in psychosocial wellbeing were found. Self-reported quality-of-life during treatment was also rated as similar between the two groups in both women and men, but was slightly lower than they would rate their quality-of-life when not in fertility treatment. LIMITATIONS, REASONS FOR CAUTION: Although response rates were high, selection bias cannot be excluded. As this study was an RCT, we assume that psychosocial characteristics of the participants were equally distributed in the two groups, thus it is unlikely that the identified psychosocial differences between the freeze-all and fresh transfer group were present already at baseline. Furthermore, the questionnaire was completed as a one-time assessment 4 days after oocyte retrieval, thus not reflecting the whole treatment process, whereas an assessment after the full completed treatment cycle is needed to draw firm conclusions about the psychosocial consequences of the whole waiting period. However, a question posted that late would be highly biased on whether or not a pregnancy had been achieved. WIDER IMPLICATIONS OF THE FINDINGS: The results indicate that individuals in the freeze-all group exhibited slightly higher levels of depressive symptoms and mood swings compared to those in the fresh transfer group. Nevertheless, it is important to note that any worries related to potential emotional strains stemming from delaying embryo transfer should not overshadow the adoption of a freeze-all approach in cases where it is clinically recommended. As long as patients are provided with comprehensive information about the treatment strategy before initiating the process, it is worth emphasising that other aspects of psychosocial wellbeing were comparable between the two groups. STUDY FUNDING/COMPETING INTEREST(S): The study is part of the Reprounion collaborative study, co-financed by the European Union, Interreg V Öresund-Kattegat-Skagerrak. L.P. reports financial support from Merck A/S. H.S.N. reports grants from Freya Biosciences ApS, Ferring Pharmaceuticals, BioInnovation Institute, Ministry of Education, Novo Nordic Foundation, Augustinus Fonden, Oda og Hans Svenningsens Fond, Demant Fonden, Ole Kirks Fond and Independent Research Fund Denmark and personal fees from Ferring Pharmaceuticals, Merck A/S, Astra Zeneca, Cook Medical, IBSA Nordic and Gedeon Richter. H.S.N is founder and chairman of the Maternity Foundation and co-developed the Safe Delivery App (non-profit). N.C.F. reports grants from Gedeon Richter, Merck A/S, Cryos International and financial support from Ferring Pharmaceuticals, Merck A/S and Gedeon Richter. N.C.F. is chairman in the steering committee for the guideline groups for The Danish Fertility Society (non-profit). P.H. reports honoraria from Merch A/S, IBSA Nordic and Gedeon Richter. A.L.M.E. reports grants and financial support from Merck A/S and Gedeon Richter. A.P. reports grants from Gedeon Richter, Ferring Pharmaceuticals, Merck A/S and personal fees from Preglem S.A., Novo Nordic Foundation, Ferring Pharmaceuticals, Gedeon Richter, Cryos International, Merch A/S, Theramex and Organon and the lend of embryoscope to the institution from Gedeon Richter. All other authors declare no conflict of interest. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT02746562.

The BISTIM study: a randomized controlled trial comparing dual ovarian stimulation (duostim) with two conventional ovarian stimulations in poor ovarian responders undergoing IVF.

STUDY QUESTION: Is the total number of oocytes retrieved with dual ovarian stimulation in the same cycle (duostim) higher than with two consecutive antagonist cycles in poor responders? SUMMARY ANSWER: Based on the number of total and mature oocytes retrieved in women with poor ovarian response (POR), there is no benefit of duostim versus two consecutive antagonist cycles. WHAT IS KNOWN ALREADY: Recent studies have shown the ability to obtain oocytes with equivalent quality from the follicular and the luteal phase, and a higher number of oocytes within one cycle when using duostim. If during follicular stimulation smaller follicles are sensitized and recruited, this may increase the number of follicles selected in the consecutive luteal phase stimulation, as shown in non-randomized controlled trials (RCT). This could be particularly relevant for women with POR. STUDY DESIGN, SIZE, DURATION: This is a multicentre, open-labelled RCT, performed in four IVF centres from September 2018 to March 2021. The primary outcome was the number of oocytes retrieved over the two cycles. The primary objective was to demonstrate in women with POR that two ovarian stimulations within the same cycle (first in the follicular phase, followed by a second in the luteal phase) led to the retrieval of 1.5 (2) more oocytes than the cumulative number of oocytes from two consecutive conventional stimulations with an antagonist protocol. In a superiority hypothesis, with power 0.8 alpha-risk 0.05 and a 35% cancellation rate, 44 patients were needed in each group. Patients were randomized by computer allocation. PARTICIPANTS/MATERIALS, SETTING, METHODS: Eighty-eight women with POR, defined using adjusted Bologna criteria (antral follicle count ≤5 and/or anti-Müllerian hormone ≤1.2 ng/ml) were randomized, 44 in the duostim group and 44 in the conventional (control) group. HMG 300 IU/day with flexible antagonist protocol was used for ovarian stimulation, except in luteal phase stimulation of the duostim group. In the duostim group, oocytes were pooled and inseminated after the second retrieval, with a freeze-all protocol. Fresh transfers were performed in the control group, frozen embryo transfers were performed in both control and duostim groups in natural cycles. Data underwent intention-to-treat and per-protocol analyses. MAIN RESULTS AND THE ROLE OF CHANCE: There was no difference between the groups regarding demographics, ovarian reserve markers, and stimulation parameters. The mean (SD) cumulative number of oocytes retrieved from two ovarian stimulations was not statistically different between the control and duostim groups, respectively, 4.6 (3.4) and 5.0 (3.4) [mean difference (MD) [95% CI] +0.4 [-1.1; 1.9], P = 0.56]. The mean cumulative numbersof mature oocytes and total embryos obtained were not significantly different between groups. The total number of embryos transferred by patient was significantly higher in the control group 1.5 (1.1) versus the duostim group 0.9 (1.1) (P = 0.03). After two cumulative cycles, 78% of women in the control group and 53.8% in the duostim group had at least one embryo transfer (P = 0.02). There was no statistical difference in the mean number of total and mature oocytes retrieved per cycle comparing Cycle 1 versus Cycle 2, both in control and duostim groups. The time to the second oocyte retrieval was significantly longer in controls, at 2.8 (1.3) months compared to 0.3 (0.5) months in the duostim group (P < 0.001). The implantation rate was similar between groups. The cumulative live birth rate was not statistically different, comparing controls versus the duostim group, 34.1% versus 17.9%, respectively (P = 0.08). The time to transfer resulting in an ongoing pregnancy did not differ in controls 1.7 (1.5) months versus the duostim group, 3.0 (1.6) (P = 0.08). No serious adverse events were reported. LIMITATIONS, REASONS FOR CAUTION: The RCT was impacted by the coronavirus disease 2019 pandemic and the halt in IVF activities for 10 weeks. Delays were recalculated to exclude this period; however, one woman in the duostim group could not have the luteal stimulation. We also faced unexpected good ovarian responses and pregnancies after the first oocyte retrieval in both groups, with a higher incidence in the control group. However, our hypothesis was based on 1.5 more oocytes in the luteal than the follicular phase in the duostim group, and the number of patients to treat was reached in this group (N = 28). This study was only powered for cumulative number of oocytes retrieved. WIDER IMPLICATIONS OF THE FINDINGS: This is the first RCT comparing the outcome of two consecutive cycles, either in the same menstrual cycle or in two consecutive menstrual cycles. In routine practice, the benefit of duostim in patients with POR regarding fresh embryo transfer is not confirmed in this RCT: first, because this study demonstrates no improvement in the number of oocytes retrieved in the luteal phase after follicular phase stimulation, in contrast to previous non-randomized studies, and second, because the freeze-all strategy avoids a pregnancy with fresh embryo transfer after the first cycle. However, duostim appears to be safe for women. In duostim, the two consecutive processes of freezing/thawing are mandatory and increase the risk of wastage of oocytes/embryos. The only benefit of duostim is to shorten the time to a second retrieval by 2 weeks if accumulation of oocytes/embryos is needed. STUDY FUNDING/COMPETING INTERESTS: This is an investigator-initiated study supported by a research Grant from IBSA Pharma. N.M. declares grants paid to their institution from MSD (Organon France); consulting fees from MSD (Organon France), Ferring, and Merck KGaA; honoraria from Merck KGaA, General Electrics, Genevrier (IBSA Pharma), and Theramex; support for travel and meetings from Theramex, Merck KGaG, and Gedeon Richter; and equipment paid to their institution from Goodlife Pharma. I.A. declares honoraria from GISKIT and support for travel and meetings from GISKIT. G.P.-B. declares Consulting fees from Ferring and Merck KGaA; honoraria from Theramex, Gedeon Richter, and Ferring; payment for expert testimony from Ferring, Merck KGaA, and Gedeon Richter; and support for travel and meetings from Ferring, Theramex, and Gedeon Richter. N.C. declares grants from IBSA pharma, Merck KGaA, Ferring, and Gedeon Richter; support for travel and meetings from IBSA pharma, Merck KGaG, MSD (Organon France), Gedeon Richter, and Theramex; and participation on advisory board from Merck KGaA. E.D. declares support for travel and meetings from IBSA pharma, Merck KGaG, MSD (Organon France), Ferring, Gedeon Richter, Theramex, and General Electrics. C.P.-V. declares support for travel and meetings from IBSA Pharma, Merck KGaA, Ferring, Gedeon Richter, and Theramex. M.Pi. declares support for travel and meetings from Ferring, Gedeon Richetr, and Merck KGaA. M.Pa. declares honoraria from Merck KGaA, Theramex, and Gedeon Richter; support for travel and meetings from Merck KGaA, IBSA Pharma, Theramex, Ferring, Gedeon Richter, and MSD (Organon France). H.B.-G. declares honoraria from Merck KGaA, and Gedeon Richter and support for travel and meetings from Ferring, Merck KGaA, IBSA Pharma, MSD (Organon France), Theramex, and Gedeon Richter. S.G. and M.B. have nothing to declare. TRIAL REGISTRATION NUMBER: Registration number EudraCT: 2017-003223-30. ClinicalTrials.gov identifier: NCT03803228. TRIAL REGISTRATION DATE: EudraCT: 28 July 2017. ClinicalTrials.gov: 14 January 2019. DATE OF FIRST PATIENT'S ENROLMENT: 3 September 2018.

Eight weeks of androgen priming by daily low-dose hCG injections before ICSI treatment in women with low ovarian reserve.

STUDY QUESTION: Does 8 weeks of continuous low-dose hCG administration increase the proportion of antral follicles that reach the preovulatory state during ovarian stimulation (OS) in women with low ovarian reserve? SUMMARY ANSWER: The proportion of antral follicles (2-10 mm) that reached the preovulatory state did not increase. WHAT IS KNOWN ALREADY: The administration of androgens prior to OS might upregulate FSH receptor (FSHR) expression on granulosa cells, making follicles more responsive to exogenous FSH stimulation during OS. LH and hCG stimulate the local follicular androgen synthesis in theca cells and may be used as an endogenous androgen priming method. Exogenous priming by testosterone and dehydroepiandrosterone (DHEA) have been shown to increase the number of retrieved oocytes and live birth rate but the studies are small, and their use is associated with side effects. STUDY DESIGN, SIZE, DURATION: A prospective, paired, non-blinded single-center study including 20 women serving as their own controls conducted between January 2021 and July 2021 at The University Hospital Copenhagen Rigshospitalet, Denmark. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants underwent two identical consecutive IVF/ICSI treatments, a Control cycle and a Study cycle, separated by ∼8 weeks (two menstrual cycles) of daily injections of 260 IU recombinant hCG (rhCG). A freeze-all strategy was applied in the Control cycle. Both IVF/ICSI cycles were performed in a fixed GnRH antagonist protocol using a daily dose of 300 IU recombinant FSH (rFSH) and GnRH antagonist 0.25 mg from stimulation days 5-6. MAIN RESULTS AND THE ROLE OF CHANCE: Follicular output rate, defined as the number of follicles >16 mm on hCG trigger day divided by the antral follicle count (2-10 mm) at baseline, did not increase after 8 weeks of hCG priming (P = 0.8). The mean number of oocytes retrieved was significantly higher after the hCG priming being 4.7 (2.8) vs 3.2 (1.7) in the Study and Control cycle, respectively (P = 0.01). The duration of stimulation was longer in the Study versus the Control cycle (P = 0.05), despite the use of identical hCG trigger criterion and similar diameters of the three biggest follicles on hCG trigger day in the two cycles (P = 0.9). LIMITATIONS, REASONS FOR CAUTION: The sample size was small, and the number of oocytes retrieved was not the primary endpoint. Larger studies are needed to confirm this finding. WIDER IMPLICATIONS OF THE FINDINGS: Long-term, low-dose rhCG administration may increase the number of oocytes retrieved during IVF/ICSI in women with low ovarian reserve, but more research is needed before firm conclusions can be drawn. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by an unrestricted grant from Gedeon Richter. A.P. reports personal consulting fees from PregLem SA, Novo Nordisk A/S, Ferring Pharmaceuticals A/S, Gedeon Richter Nordics AB, Cryos International, and Merck A/S outside the submitted work and payment or honoraria for lectures from Gedeon Richter Nordics AB, Ferring Pharmaceuticals A/S, Merck A/S, and Theramex and Organon & Co. Grants to the institution have been provided by Gedeon Richter Nordics AB, Ferring Pharmaceuticals A/S, and Merck A/S and receipt of equipment by the institution from Gedeon Richter Nordics AB is reported. The remaining authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Identifier: NCT04643925.

The time interval between oocyte retrieval and frozen embryo transfer does not impact reproductive outcomes.

RESEARCH QUESTION: Does the time interval between oocyte retrieval and frozen embryo transfer (FET) affect pregnancy outcomes after a freeze-all strategy? DESIGN: Retrospective study including a total of 5995 patients who underwent their first FET following a freeze-all cycle between 1 January 2017 and 31 December 2020. Patients were divided into immediate (the interval between oocyte retrieval and the day of first FET ≤40 days), delayed (>40 days but ≤180 days) and overdue groups (>180 days). Pregnancy and neonatal outcomes were analysed, and multivariable regression analysis was used to study the effect of FET timing on the live birth rate (LBR) in the entire cohort and the different subgroups. RESULTS: The LBR was significantly lower in the overdue group than in the delayed group (34.9% versus 42.8%, P = 0.002); however, after adjusting for confounding factors, the difference was not statistically significant. The immediate group had a comparable LBR (36.9%) to the other two groups in both the crude and adjusted analyses. Multivariable regression analysis showed no impact of FET timing on LBR in the whole cohort or in the subgroups according to ovarian stimulation protocol, trigger type, insemination method, reason for freezing all, FET protocol or transferred embryo stage. CONCLUSIONS: The time interval between oocyte retrieval and FET does not impact reproductive outcomes. Unnecessary delays in FET should be avoided to shorten the time to live birth.

Nature (almost) always prevails - challenging the status quo of artificial cycle frozen embryo transfers.

Frozen embryo transfers (FET) have become increasingly popular in assisted reproductive technology (ART) due to advancements in cryopreservation techniques and the implementation of the 'freeze-all' strategy. The choice between artificial or natural cycles for FET preparation has been a subject of debate, considering factors such as endometrial receptivity, flexibility of scheduling and pregnancy outcomes. While artificial cycle protocols offer convenience and flexibility, studies have suggested potential drawbacks, including higher miscarriage rates and a greater risk of hypertensive disorders during pregnancy. In contrast, natural cycle protocols involve a frequently demanding monitoring of both endometrial proliferation and follicular growth, which may lead to increased clinic visits and scheduling issues. Multiple strategies have been proposed to enhance the usage of natural cycle FET, including addressing anovulation through minimal stimulation, reducing cycle monitoring and exploring novel FET approaches. These novel approaches, such as widening the window for human chorionic gonadotrophin administration and the natural proliferative phase protocol, offer promising outcomes and increased convenience for patients. However, further research is needed to establish the optimal timing and effectiveness of these strategies. Overall, enhancing the practicality of natural cycle FETs is crucial for expanding their utilization during ART.

Platelet extracellular vesicles are efficient delivery vehicles of doxorubicin, an anti-cancer drug: preparation and in vitro characterization.

Platelet extracellular vesicles (PEVs) are an emerging delivery vehi for anticancer drugs due to their ability to target and remain in the tumor microenvironment. However, there is still a lack of understanding regarding yields, safety, drug loading efficiencies, and efficacy of PEVs. In this study, various methods were compared to generate PEVs from clinical-grade platelets, and their properties were examined as vehicles for doxorubicin (DOX). Sonication and extrusion produced the most PEVs, with means of 496 and 493 PEVs per platelet (PLT), respectively, compared to 145 and 33 by freeze/thaw and incubation, respectively. The PEVs were loaded with DOX through incubation and purified by chromatography. The size and concentration of the PEVs and PEV-DOX were analyzed using dynamic light scattering and nanoparticle tracking analysis. The results showed that the population sizes and concentrations of PEVs and PEV-DOX were in the ranges of 120-150 nm and 1.2-6.2 × 1011 particles/mL for all preparations. The loading of DOX determined using fluorospectrometry was found to be 2.1 × 106, 1.7 × 106, and 0.9 × 106 molecules/EV using freeze/thaw, extrusion, and sonication, respectively. The internalization of PEVs was determined to occur through clathrin-mediated endocytosis. PEV-DOX were more efficiently taken up by MDA-MB-231 breast cancer cells compared to MCF7/ADR breast cancer cells and NIH/3T3 cells. DOX-PEVs showed higher anticancer activity against MDA-MB-231 cells than against MCF7/ADR or NIH/3T3 cells and better than acommercial liposomal DOX formulation. In conclusion, this study demonstrates that PEVs generated by PLTs using extrusion, freeze/thaw, or sonication can efficiently load DOX and kill breast cancer cells, providing a promising strategy for further evaluation in preclinical animal models. The study findings suggest that sonication and extrusion are the most efficient methods to generate PEVs and that PEVs loaded with DOX exhibit significant anticancer activity against MDA-MB-231 breast cancer cells.

What is the context?● Current synthetic drug delivery systems can have limitations and side effects.● Platelet extracellular vesicles (PEVs) are a natural and potentially safer alternative for delivering cancer drugs to tumors.● However, there is still a lack of understanding about how to produce PEVs and how effective they are in delivering drugs.What is new?● We compared different methods for producing PEVs from clinical-grade platelets and found that sonication and extrusion were the most effective methods.● The PEVs were loaded with a cancer drug called doxorubicin (DOX) and tested their ability to kill breast cancer cells.What is the impact?● PEVs loaded with DOX were effective at killing cancer cells, especially MDA-MB-231 breast cancer cells.● This study demonstrates that PEVs are a promising strategy for delivering cancer drugs to tumors and that sonication and extrusion are the most efficient methods for producing PEVs.● The results suggest that further evaluation of PEVs in preclinical animal models is warranted to determine their potential as a cancer drug delivery system.Abbreviations: ADP: adenosine diphosphate; bFGF: basic fibroblast growth factor; BSA: bovine serum albumin; CD41: platelet glycoprotein IIb; CD62P: P-selectin; CFDASE: 5-(and-6)-carboxyfluorescein diacetate: succinimidyl ester; CPLT: cryopreserved platelet; CPZ: chlorpromazine hydrochloride; CTC: circulating tumor cell; DMSO: dimethyl sulfoxide; DDS: drug delivery system; DOX: doxorubicin; EPR: enhanced permeability and retention; EV: extracellular vesicle; FBS: fetal bovine serum; GMP: good manufacturing practice; GF: growth factor; HER2: human epidermal growth factor receptor 2; HGF: hepatocyte growth factor; Lipo-DOX: liposomal doxorubicin; MDR: multi-drug resistance; MMP-2: matrix metalloproteinase-2; MP: microparticle; MSC: mesenchymal stromal cell; NP: nanoparticle; NTA: nanoparticle tracking analysis; PAR-1: protease activated receptor-1; PAS: platelet additive solution; PBS: phosphate-buffered saline; PC: platelet concentrate; PEG: polyethylene glycol; PEV: platelet-derived extracellular vesicle; DOX-PEV: doxorubicin-loaded platelet-derived extracellular vesicle-encapsulated; PFA: paraformaldehyde; PF4: platelet factor 4; P-gp: P-glycoprotein; PLT: platelet; PS: phosphatidylserine; SDS-PAGE: sodium dodecylsulfate polyacrylamide gel electrophoresis; SEM: scanning electron microscopy; TCIPA: tumor cell-induced PLT aggregation; TDDS: targeted drug delivery system; TEG: thromboelastography; TF: tissue factor; TF-EV: extracellular vesicle expressing tissue factor; TME: tumor microenvironment; TNBC: triple-negative breast cancer; TXA2: thromboxane-A2; VEGF: vascular endothelial growth factor; WHO: World Health Organization.

Clinical outcome of different embryo transfer strategies after late rescue ICSI procedure: a 10-year total fertilisation failure cohort study.

BACKGROUND: Late rescue intracytoplasmic sperm injection (r-ICSI) has not been widely accepted as an alternative solution for unexpected total fertilisation failure (TFF) after in vitro fertilisation (IVF), due to the time-dependent in vitro deterioration of oocyte quality and endometrial growth not being synchronised with embryo development. This study aimed to evaluate the safety profile and effectiveness of freeze-all blastocyst transfer in combination with late r-ICSI. METHODS: This was a retrospective cohort study carried out at the Reproductive Centre of Peking University Third Hospital, Beijing, China. All participants received treatment between 2009 and 2019. 2,270 patients in the aggregate encountered unexpected TFF during 149,054 cycles of IVF and adopted a late r-ICSI procedure. Among these patients, 263 women did not have cleavage-stage embryos available for evaluation. The remaining patients were grouped according to different embryo transfer (ET) strategies (926 women in Group 1 underwent fresh ET, 365 women in Group 2 underwent freeze-all ET, 716 women in Group 3 experienced blastulation failure). Patients received different ET strategies after r-ICSI, with the main outcome measures included live birth rate (LBR), cumulative live birth rate (cLBR), and conservative cLBR. RESULTS: TFF occurred in 7.4% of all IVF cycles. Group 1 tended to be older at oocyte retrieval, with more infertile years, higher follicle-stimulating hormone (FSH) levels, higher gonadotropin consumption, and fewer oocytes retrieved. Group 2 exhibited considerably better LBRs following the first ET cycle (37.53% vs. 4.64%) and cLBRs (52.60% vs. 8.21%). After adjustment for covariates using binary logistic regression analyses, Group 2 still showed better obstetric performance in LBRs [OR:11.77, 95% CI (8.42-16.45)], cLBRs (OR:11.29, 95% CI (7.84-16.27)], and conservative cLBRs (OR:2.55, 95% CI (1.83-3.55)]. Additionally, the two groups showed similar miscarriage rates, whilst no new-borns with malformations or congenital diseases were reported. CONCLUSIONS: Freeze-all blastocyst stage ET serves as an optimal strategy to support late r-ICSI. However, for women with limited oocytes available for r-ICSI use, weighing the benefits against the costs of the procedure might be prudent before implementing in vitro blastulation.