Culture Of Preimplantation Embryos Research Articles

P-241 The in vivo human uterine pH and uterine fluid composition differs from pH and composition of clinically used in vitro preimplantation embryo culture media

Abstract Study question To study the pH and uterine fluid composition in the human uterus three days after a positive LH test or ovum pick-up. Summary answer The uterine pH three days after a positive LH test or ovum pick-up was 6.8. Concentrations of 37 components were determined in uterine fluid. What is known already In assisted reproductive technologies (ART), the in vitro culture of human preimplantation embryos is known to play a crucial role in the success of In Vitro Fertilization (IVF) treatments. It affects live birth rates and child outcomes such as birth weight. Numerous commercial embryo culture media are routinely used in clinical practice worldwide, but their composition is primarily based on laboratory-based clinical insights and experimental studies with animal models. Studies on the natural human preimplantation embryo environment during the physiologically relevant time of the menstrual cycle are limited. Study design, size, duration A cross sectional clinical study was conducted to study the uterine pH and the composition of human uterine fluid. The uterine pH was measured in 53 women on the third day after LH surge (N = 46) or ovum pickup (N = 7), as that time in the menstrual cycle is associated with endometrial receptivity for embryo implantation. Twenty-two samples of aspirated uterine fluid, that were collected at the same time, were analyzed for the concentrations of thirty-seven components. Participants/materials, setting, methods Healthy women of reproductive age with normal functional uterine anatomy were included. Uterine pH was determined using pH probe inserted through outer sheath of an Embryo Transfer (ET) catheter at the lithotomy position. Uterine fluid was then aspirated using a syringe connected to outer sheath of this ET catheter. Collected samples were analyzed using a Cobas 8000 chemistry analyser and ultra-performance liquid chromatography-tandem mass spectrometry. Main results and the role of chance The mean pH in the uterine cavity on the third day after a positive LH test (6.75 ± 0.22) or ovum pick-up (6.82 ± 0.18) was clearly lower than the pH used in routine clinical practice for preimplantation embryo culture (pH 7.3 ± 0.1). Calcium, phosphate, lactate(L), pyruvate, albumin and 21 amino acids were present at different concentrations in human uterine fluid compared to most commonly used preimplantation embryo culture media. Immunoglobulins, citrulline, ornithine and uric acid were present in uterine fluid, but not in clinically used culture media. Limitations, reasons for caution As the uterine cavity is only one part of the reproductive tract, our measurements do not fully represent the complete in vivo environment of preimplantation embryo development. We only studied 37 components, recognizing that uterine fluid likely contains additional components. Wider implications of the findings The observed differences between the uterine pH and the composition of uterine fluid and the pH and composition of preimplantation embryo culture media used in routine clinical practice could be a starting point to further optimize in vitro embryo culture in ART treatments. Trial registration number Not applicable

P-789 Trophoblast organoids as a 3D model for the study of oxygen concentration during in vitro preimplantation embryo culture

Abstract Study question To determine if trophoblast organoids could represent a relevant robust model to study the impact of oxygen concentration on human preimplantation embryo development. Summary answer Transcriptomic analysis of trophoblast organoids cultured in monophasic (5%) or biphasic (5-2%) O2 concentration identified 1,184 RNAs differentially expressed. What is known already Our team has previously demonstrated that a biphasic (5-2%) O2 concentration strategy during preimplantation embryo culture (from Day 0 to Day 6) significantly improved blastulation and live birth rates in in vitro fertilization (IVF). We also identified differentially expressed RNAs between monophasic and biphasic O2 strategies through whole transcriptome analysis on human embryos donated for research. However, the number of embryos donated to research is limited, they are all genetically different, and their use iethically controversial, representing a significative drawback to experimentation. Latest studies on trophoblast organoids indicate that they could represent a relevant model for studying preimplantation embryo development. Study design, size, duration A prospective monocentric study approved by the Institutional Review Board (I.R.B.) was conducted between February 2022 and September 2023: four early first-trimester human placentas were collected after surgical abortions and used for derivation of organoids in a 3D culture system. The protocol for organoid culture is described in the study of Sheridan and al, 2020. Organoids were cultured with either a monophasic or a biphasic oxygen concentration strategy. Participants/materials, setting, methods Trophoblast organoids were either exposed to 5% oxygen concentration during 5 days or to 5% O2 for 3 days and to 2% O2 for 2 days. Total RNA extraction of 21 organoids for each condition was performed. After whole transcriptome analysis using human Clariom D arrays (ThermoFisher Scientific®), microarray data were normalized and differentially expressed RNAs were identified using the Transcriptome Analysis Console software; the genetic network was generated with Ingenuity Pathway Analysis (Qiagen®). Main results and the role of chance Transcriptomic analysis of trophoblast organoids cultured in monophasic (5%) or biphasic (5-2%) O2 concentration identified 1,184 RNAs that were differentially expressed depending on the O2 strategy (fold change >2 or <-2, p < 0.05), with most of them (75.1%, n = 889/1,184) being downregulated in the biphasic (5-2%) O2 group. IPA analysis highlighted downregulation of transcripts involved in cell survival and differentiation as well as upregulation of transcripts involved in embryo angiogenesis and vascularization of extraembryonic tissue. The transcript HIF1a was upregulated in organoids cultured in biphasic strategy compared to monophasic strategy (fold change 2, p = 0.0129). Comparison between differentially expressed transcripts in monophasic and biphasic strategies highlighted 22 transcripts in common between organoids and embryos donated to research from our previous study. Limitations, reasons for caution Our study was limited by a low sample size. Wider implications of the findings This innovative model of trophoblast organoids could help us to overcome the rarity as well as the genetic/epigenetic heterogeneity associated with IVF human embryos donated to the research, thus leading to the realization of large-scale experimentations and promoting the identification of new non-invasive predictive biomarkers for IVF. Trial registration number not applicable

Influence of the storage conditions of embryo culture media on mouse development.

The culture of preimplantation embryos in vitro is an important method for human and mouse reproductive technology. This study aims to investigate the influence of different conditions of culture media on the preimplantation stage of mouse embryos cultured in vitro, and monitor the post-implantation development of new mice after embryo transfer to surrogate females. We demonstrated here that mouse embryos cultured in vitro in fresh M16, KSOM, Global, and HTF embryo culture media from one cell to the blastocyst stage and the subsequent embryo transfer to surrogate females are able to proceed through post-implantation development and, after birth, develop into healthy mice. However, culture of embryos in differently aged media shows various (often unpredictable) results. To find the optimal storage conditions of culture media, we suggest that the freezing and long-term storage of these media at - 80°C will not influence the quality of the media. To test this hypothesis, we grew embryos from one cell to blastocysts in vitro in the selected media after thawing and subsequently transferring them to surrogate females. Embryo culture in these four media after thawing does not affect preimplantation and postnatal mouse development. Thus, we have shown that storage of embryo culture media at low temperature (- 80°C) does not impact the quality of the media, and subsequently, it can be used for the culture of embryos for the full preimplantation period, the same as in fresh media.

The reproductive potential of vitrified-warmed euploid embryos declines following repeated uterine transfers

BackgroundRecurrent implantation failure (RIF) represents a vague clinical condition with an unclear diagnostic challenge that lacks solid scientific underpinning. Although euploid embryos have demonstrated consistent implantation capabilities across various age groups, a unanimous agreement regarding the advantages of preimplantation genetic testing for aneuploidy (PGT-A) in managing RIF is absent. The ongoing discussion about whether chromosomal aneuploidy in embryos significantly contributes to recurrent implantation failure remains unsettled. Despite active discussions in recent times, a universally accepted characterization of recurrent implantation failure remains elusive. We aimed in this study to measure the reproductive performance of vitrified-warmed euploid embryos transferred to the uterus in successive cycles.MethodsThis observational cohort study included women (n = 387) with an anatomically normal uterus who underwent oocyte retrieval for PGT-A treatment with at least one biopsied blastocyst, between January 2017 and December 2021 at a university-affiliated public fertility center. The procedures involved in this study included ICSI, blastocyst culture, trophectoderm biopsy and comprehensive 24-chromosome analysis of preimplantation embryos using Next Generation Sequencing (NGS). Women, who failed a vitrified-warmed euploid embryo transfer, had successive blastocyst transfer cycles (FET) for a total of three using remaining cryopreserved euploid blastocysts from the same oocyte retrieval cycle. The primary endpoints were sustained implantation rate (SIR) and live birth rate (LBR) per vitrified-warmed single euploid embryo. The secondary endpoints were mean euploidy rate (m-ER) per cohort of biopsied blastocysts from each patient, as well as pregnancy and miscarriage rates.ResultsThe mean age of the patient population was 33.4 years (95% CI 32.8–33.9). A total of 1,641 embryos derived from the first oocyte retrieval cycle were biopsied and screened. We found no associations between the m-ER and the number of previous failed IVF cycles among different ranges of maternal age at oocyte retrieval (P = 0.45). Pairwise comparisons showed a significant decrease in the sustained implantation rate (44.7% vs. 30%; P = 0.01) and the livebirth rate per single euploid blastocyst (37.1% vs. 25%; P = 0.02) between the 1st and 3rd FET. The cumulative SIR and LBR after up to three successive single embryo transfers were 77.1% and 68.8%, respectively. We found that the live birth rate of the first vitrified-warmed euploid blastocyst transferred decreased significantly with the increasing number of previously failed IVF attempts by categories (45.3% vs. 35.8% vs. 27.6%; P = 0.04). A comparable decrease in sustained implantation rate was also observed but did not reach statistical significance (50% vs. 44.2 vs. 37.9%; P = NS). Using a logistic regression model, we confirmed the presence of a negative association between the number of previous IVF failed attempts and the live birth rate per embryo transfer cycle (OR = 0.76; 95% CI 0.62–0.94; P = 0.01).ConclusionsThese findings are vital for enhancing patient counseling and refining management strategies for individuals facing recurrent implantation failure. By tailoring interventions based on age and ovarian reserve, healthcare professionals can offer more personalized guidance, potentially improving the overall success rates and patient experiences in fertility treatments.Trial registration numberN/A.

#124 : Microtubule Stability is Associated with the Functional Activity of Mitochondria for the Mouse Preimplantation Embryo Development

Background and Aims: Mitochondria have a pivotal role in the quality of embryos and good development to a healthy embryo pregnancy. Also, mitochondrial dysfunction increases during the aging of the embryos. But there is still a debate about the main cause of mitochondrial dysfunction in the aged embryos. We investigate that effect of microtubule stabilizer (MTS) as Taxol, EpD and microtubule disturber (MTD) as VNB in the preimplantation embryo of the mouse. Method: We performed preimplantation embryo culture with MTS and MTD. Then we assess development ratio and mitochondria functional activity between control and MTS and MTD. We performed comparable analysis of mitochondrial motility between MTS treated and MTD treated embryos by confocal live imaging. Results: In the MTS treated embryos, well-developed embryos with microtubules formation were present in the ooplasm. However, in the MTD treated embryos group, less development and poor microtubule polymer formation was observed in the ooplasm. Microtubules was also demonstrated by depolymerization and the clustering form in the ooplasm of MTD treated embryos. The high dynamic movement of the cytoskeleton with a mitochondrion compared to the MTD treated embryos. Conclusion: Our data suggest that the new function of MTS as Taxol, EpD shows promoting competence of embryo development with enhanced activity of a mitochondrial function. Therefore, MTS is useful as a supplement in vitro culture media of embryos.

Phenotypic Analysis of Preimplantation Mouse Embryos in Culture

Preimplantation embryo culture is a valuable approach to investigate a preimplantation lethal phenotype. Standard culture methods have been perfected such that the entire preimplantation period and the process of implantation can be followed in vitro. This protocol provides modifications for the analysis of clutches of embryos from heterozygous matings specifically for the purpose of distinguishing a preimplantation phenotype in homozygous mutants.

Long-term culture induces Bax-dependent apoptosis in rat preimplantation embryos.

Although rat preimplantation embryos are necessary for producing genetically modified rats, their in vitro culture remains a challenge. Rat zygotes can develop from the one-cell stage to the blastocyst stage in vitro; however, long-term culture reduces their developmental competence via an unknown mechanism. In this study, we examined how in vitro conditions affect rat preimplantation embryos, which may explain this reduced competence. Comprehensive gene expression analysis showed that genes related to apoptosis and energy metabolism were differentially expressed in rat embryos cultured long-term in vitro compared with those developed in vivo. Furthermore, we found that the expression of Bak1 and Bax, which are responsible for mitochondrial outer membrane permeabilization, were more upregulated in embryos cultured in vitro than those developed in vivo. Similarly, apoptosis-dependent DNA fragmentation was also exacerbated in in vitro culture conditions. Finally, gene disruption using CRISPR/Cas9 showed that Bax, but not Bak1, was responsible for these effects. These findings suggest that long-term in vitro culture induces Bax-dependent apoptosis through the mitochondrial pathway and may provide clues to improve the long-term culture of rat preimplantation embryos for genetic engineering research.

O-008 The composition of commercially available human preimplantation embryo culture media

Abstract Study question What is the composition of currently available commercial human preimplantation embryo culture media from eleven different brands for each stage of preimplantation embryo development? Summary answer Besides similarities in embryo culture medium composition between brands, there were also differences in composition for which there does not seem to be a rationale. What is known already Although a lot remains uncertain, there seems to be some consensus in the scientific literature on the environmental and nutritional needs of preimplantation embryos in in vitro culture, at least for certain components. Since suppliers do not disclose the exact formulations of their media, it is unclear whether the embryo culture media currently used in IVF laboratories meet these suggested conditions. We previously published composition analyses of a limited number of culture media, but have now repeated this analysis and have included a larger number of media from eleven brands of human preimplantation embryo culture media. Study design, size, duration Forty-seven human embryo culture media and protein supplements were purchased between December 2019 and June 2020. Upon arrival, each complete medium (n = 23), unsupplemented medium (n = 14), and supplement (n = 10) was aliquotted in Eppendorf tubes, snap frozen in liquid nitrogen and stored in -80oC until composition analysis in November 2021. Additionally, unsupplemented media were supplemented with each available supplement from the same brand (n = 33 combinations) and then also aliquotted, snap frozen and stored in -80oC until analysis. Participants/materials, setting, methods The concentration of forty components was determined in all collected samples (n = 80). Seven ions, glucose, three immunoglobulins, uric acid, alanine aminotransferase (ASAT), aspartate aminotransferase (ALAT), albumin, and the total amount of proteins were determined in each sample using a Cobas 8000 Analyser (Roche Diagnostics). Analysis of pyruvate, lactate, carnitine and twenty-one amino acids was achieved with Ultra-high Performance Liquid Chromatography-Mass Spectometry (UPLC-MS/MS). Main results and the role of chance Our analysis of the concentration of 40 components in ready to use embryo culture media of most available brands on the market showed that in general the culture media follow generally accepted assumptions on the changing needs of an embryo during early development. However, there were clear differences between brands, and no two embryo culture media were the same. For example, pyruvate concentrations were higher in fertilization and cleavage stage media and lower in blastocyst stage media, whereas glucose was relatively high in fertilization media, lower in cleavage stage media, and higher again in blastocyst media. This follows previous findings that demonstrate that pyruvate is the main energy source until blastocyst stage and that glucose becomes the main energy source for blastocysts. Other components, like lactate for example, followed different patterns in the sequential media of different brands, and concentrations also differed between brands. The composition of continuous media resembled the composition of the other media of the same brand, but differed between brands. Interestingly, some of the culture media brands belong to the same parent company, but differ in their composition. The rationale of such differences is not clear. Research providing such rationale seems warranted. Limitations, reasons for caution The analysed embryo culture media may contain other components that were not investigated in this study. Wider implications of the findings Detailed information on human embryo culture medium composition, including the exact concentrations of each ingredient, is much needed to in the end be able to understand its effect on IVF outcomes, and to facilitate the scientific improvement of media for human preimplantation embryo culture. Trial registration number not applicable

Effects of Assisted Reproductive Technologies on Social Behavior of BTBR Mice – A Model of Autism Spectrum Disorder

The present work is the first attempt to study the effect of such assisted reproductive technologies (ARTs), as in vitro culture of preimplantation embryos on the social behavior of offspring, using BTBR mice (BTBR T+Itpr3tf/J) as an idiopathic model of a-utism. The C57BL/6J mice were used as controls. Social behavior was studied in adult offspring mice obtained after in vitro culture and embryo transfer (ET) (groups ET-C57BL/6J and ET-BTBR). The BTBR mice demonstrated the reduced levels of social recognition and affiliation compared to C57BL/6J mice. The social affiliation and recognition test revealed that ET-C57BL/6J males had a high level of social interaction, which was of similar magnitude as in naturally conceived C57BL/6J males. However, ET-C57BL/6J and ET-BTBR females demonstrated a decrease in interest to a new stranger compared to naturally conceived controls of the same sex, which was revealed in a social recognition session of this test. Thus, the in vitro culture affected the social recognition in the offspring of C57BL/6J and BTBR mice, but only in females.

Non-invasive evaluation of embryo quality for the selection of transferable embryos in human in vitro fertilization-embryo transfer.

The ultimate goal of human assisted reproductive technology is to achieve a healthy pregnancy and birth, ideally from the selection and transfer of a single competent embryo. Recently, techniques for efficiently evaluating the state and quality of preimplantation embryos using time-lapse imaging systems have been applied. Artificial intelligence programs based on deep learning technology and big data analysis of time-lapse monitoring system during in vitro culture of preimplantation embryos have also been rapidly developed. In addition, several molecular markers of the secretome have been successfully analyzed in spent embryo culture media, which could easily be obtained during in vitro embryo culture. It is also possible to analyze small amounts of cell-free nucleic acids, mitochondrial nucleic acids, miRNA, and long non-coding RNA derived from embryos using real-time polymerase chain reaction (PCR) or digital PCR, as well as next-generation sequencing. Various efforts are being made to use non-invasive evaluation of embryo quality (NiEEQ) to select the embryo with the best developmental competence. However, each NiEEQ method has some limitations that should be evaluated case by case. Therefore, an integrated analysis strategy fusing several NiEEQ methods should be urgently developed and confirmed by proper clinical trials.

Biochemical Hazards during Three Phases of Assisted Reproductive Technology: Repercussions Associated with Epigenesis and Imprinting.

Medically assisted reproduction, now considered a routine, successful treatment for infertility worldwide, has produced at least 8 million live births. However, a growing body of evidence is pointing toward an increased incidence of epigenetic/imprinting disorders in the offspring, raising concern that the techniques involved may have an impact on crucial stages of early embryo and fetal development highly vulnerable to epigenetic influence. In this paper, the key role of methylation processes in epigenesis, namely the essential biochemical/metabolic pathways involving folates and one-carbon cycles necessary for correct DNA/histone methylation, is discussed. Furthermore, potential contributors to epigenetics dysregulation during the three phases of assisted reproduction: preparation for and controlled ovarian hyperstimulation (COH); methylation processes during the preimplantation embryo culture stages; the effects of unmetabolized folic acid (UMFA) during embryogenesis on imprinting methyl “tags”, are described. Advances in technology have opened a window into developmental processes that were previously inaccessible to research: it is now clear that ART procedures have the potential to influence DNA methylation in embryonic and fetal life, with an impact on health and disease risk in future generations. Critical re-evaluation of protocols and procedures is now an urgent priority, with a focus on interventions targeted toward improving ART procedures, with special attention to in vitro culture protocols and the effects of excessive folic acid intake.

Surface functionalization of poly(dimethylsiloxane) substrates facilitates culture of pre-implantation mouse embryos by blocking non-selective adsorption.

Poly(dimethylsiloxane) (PDMS) is widely used in biomedical settings such as microfluidics for its optical transparency, castability, gas permeability and relative biocompatibility. While PDMS devices with certain modifications or treatments have been used for mammalian pre-implantation embryo culture, it is unclear why native PDMS leads to significant embryo death. In this study, we employ Nile Red as a model hydrophobic small molecule to demonstrate that significant hydrophobic sequestration occurs on native PDMS substrates even with a bovine serum albumin-containing KSOM pre-equilibration. Our results suggest that this small molecule sequestration has detrimental effects on mouse embryo development in PDMS static culture wells, with 0% blastocyst development rates from embryos cultured on native PDMS. We found that prior saturation of the PDMS culture well with water vapour only rescues about 10% of blastocyst development rates, indicating osmolality alone is not responsible for the high rates of embryo arrest. We also present a safe and simple Pluronic F127 pretreatment for PDMS substrates that successfully circumvented the harmful effects of native PDMS, achieving a blastocyst and implantation rate akin to that of our polystyrene controls. Our results call into question how researchers and clinicians can account for the alterations in medium composition and embryo secretions when using hydrophobic substrates, especially in the mammalian embryo culture setting where minimum effective concentrations of peptides and amino acids are commonplace.

From lessons on the long-term effects of the preimplantation environment on later health to a "modified ART-DOHaD" animal model.

BackgroundAt its earliest stages, mammalian embryonic development is apparently simple but vulnerable. The environment during the preimplantation period, which only lasts a couple of days, has been implicated in adult health, extending to such early stages the concept of the developmental origin of health and disease (DOHaD).MethodsIn this review, we first provide a brief history of assisted reproductive technology (ART) focusing on in vitro culture and its outcomes during subsequent development mainly in mice and humans. Further, we introduce the “MEM mouse,” a novel type 2 diabetes mouse model generated by in vitro culture of preimplantation embryos in alpha minimum essential medium (αMEM).Main findingsThe association between ART and its long‐term effects has been carefully examined for its application in human infertility treatment. The “MEM mouse” develops steatohepatitis and kidney disease with diabetes into adulthood.ConclusionThe close association between the environment of preimplantation and health in postnatal life is being clarified. The approach by which severe mouse phenotypes are successfully induced by manipulating the environment of preimplantation embryos could provide new chronic disease animal models, which we call “modified ART‐DOHaD” animal models. This will also offer insights into the mechanisms underlying their long‐term effects.

Optimised CO2-containing medium for in vitro culture and transportation of mouse preimplantation embryos without CO2 incubator.

Conventional in vitro culture and manipulation of mouse embryos require a CO2 incubator, which not only increases the cost of performing experiments but also hampers the transport of embryos to the other laboratories. In this study, we established and tested a new CO2 incubator-free embryo culture system and transported embryos using this system. Using an Anaero pouch, which is a CO2 gas-generating agent, to increase the CO2 partial pressure of CZB medium to 4%-5%, 2-cell embryos were cultured to the blastocyst stage in a sealed tube without a CO2 incubator at 37°C. Further, the developmental rate to blastocyst and full-term development after embryo transfer were comparable with those of usual culture method using a CO2 incubator (blastocyst rate: 97% versus 95%, respectively; offspring rate: 30% versus 35%, respectively). Furthermore, using a thermal bottle, embryos were reliably cultured using this system for up to 2 days at room temperature, and live offspring were obtained from embryos transported in this simple and very low-cost manner without reducing the offspring rate (thermal bottle: 26.2% versus CO2 incubator: 34.3%). This study demonstrates that CO2 incubators are not essential for embryo culture and transportation and that this system provides a useful, low-cost alternative for mouse embryo culture and manipulation.

Cytokines in culture media of preimplantation embryos during in vitro fertilization: Impact on embryo quality.

Cytokine support of embryonic development includes promotion of implantation and protection of blastomeres from cell stress and apoptosis. Correlations between embryo quality and concentrations of specific cytokines in culture media of human embryos have been investigated for many years. The aim of this study was to assess the concentrations of cytokines in preimplantation embryo culture media and to investigate their relationships with embryo quality and in vitro fertilization (IVF) outcomes. Seventy-two samples were obtained from 39 infertile couples undergoing IVF or intracytoplasmic sperm injection treatment between October 2018 and May 2019. Each embryo was cultured separately, and the embryo culture medium was collected 72h after fertilization. Before embryo transfer on day 3, a morphological evaluation of each embryo was performed. Cytokine concentrations of each culture medium were analyzed for 23 selected cytokines using the Multiplex Cytokine/Chemokine Panel II Assay (Merck Millipore®). The results were categorized into two groups (top-quality and non-top-quality embryos). The median age of the 39 patients was 34years. Nine of 23 cytokines were quantified and compared between the top-quality embryo group and non-top-quality embryo group. Among the nine cytokines, CCL15, CCL27, and CXCL-12 were significantly elevated in the top-quality embryo group. These results suggested that specific cytokines measured in human embryo culture media can be used to predict embryo quality and IVF outcomes.

Biphasic (5–2%) oxygen concentration strategy significantly improves the usable blastocyst and cumulative live birth rates in in vitro fertilization

Oxygen (O2) concentration is approximately 5% in the fallopian tube and 2% in the uterus in humans. A “back to nature” approach could increase in vitro fertilization (IVF) outcomes. This hypothesis was tested in this monocentric observational retrospective study that included 120 couples who underwent two IVF cycles between 2014 and 2019. Embryos were cultured at 5% from day 0 (D0) to D5/6 (monophasic O2 concentration strategy) in the first IVF cycle, and at 5% O2 from D0 to D3 and 2% O2 from D3 to D5/6 (biphasic O2 concentration strategy) in the second IVF cycle. The total and usable blastocyst rates (44.4% vs. 54.8%, p = 0.049 and 21.8% vs. 32.8%, p = 0.002, respectively) and the cumulative live birth rate (17.9% vs. 44.1%, p = 0.027) were significantly higher with the biphasic (5%-2%) O2 concentration strategy. Whole transcriptome analysis of blastocysts donated for research identified 707 RNAs that were differentially expressed in function of the O2 strategy (fold-change > 2, p value < 0.05). These genes are mainly involved in embryo development, DNA repair, embryonic stem cell pluripotency, and implantation potential. The biphasic (5–2%) O2 concentration strategy for preimplantation embryo culture could increase the “take home baby rate”, thus improving IVF cost-effectiveness and infertility management.

Amino Acids and the Early Mammalian Embryo: Origin, Fate, Function and Life-Long Legacy.

Amino acids are now recognised as having multiple cellular functions in addition to their traditional role as constituents of proteins. This is well-illustrated in the early mammalian embryo where amino acids are now known to be involved in intermediary metabolism, as energy substrates, in signal transduction, osmoregulation and as intermediaries in numerous pathways which involve nitrogen metabolism, e.g., the biosynthesis of purines, pyrimidines, creatine and glutathione. The amino acid derivative S-adenosylmethionine has emerged as a universal methylating agent with a fundamental role in epigenetic regulation. Amino acids are now added routinely to preimplantation embryo culture media. This review examines the routes by which amino acids are supplied to the early embryo, focusing on the role of the oviduct epithelium, followed by an outline of their general fate and function within the embryo. Functions specific to individual amino acids are then considered. The importance of amino acids during the preimplantation period for maternal health and that of the conceptus long term, which has come from the developmental origins of health and disease concept of David Barker, is discussed and the review concludes by considering the potential utility of amino acid profiles as diagnostic of embryo health.

THE INTRODUCTION OF A GROUP CULTURE PROTOCOL IN DONOR OOCYTE-RECIPIENT CYCLES DID NOT INCREASE THE TOTAL USEABLE BLASTOCYST RATES: A RETROSPECTIVE STUDY

Group culture of human preimplantation embryos could increase the number of useable blastocysts per in vitro fertilization (IVF) cycle. The present study compares the outcomes of a specific group embryo culture strategy vs. single culture of 1 embryo per media droplet.

A pilot study investigating a novel particle-based growth factor delivery system for preimplantation embryo culture.

Can vascular endothelial growth factor (VEGF)-loaded silica supraparticles (V-SPs) be used as a novel mode of delivering VEGF to the developing preimplantation embryo in vitro? Supplementation of embryo culture media with V-SPs promoted embryonic development in a manner equivalent to media supplemented with free VEGF. VEGF is a maternally derived growth factor that promotes preimplantation embryonic development in vitro. However, its use in clinical media has limitations due to its low stability in solution. This study was a laboratory-based analysis utilising a mouse model. V-SPs were prepared in vitro and supplemented to embryonic culture media. The bioactivity of V-SPs was determined by analysis of blastocyst developmental outcomes (blastocyst development rate and total cell number). SPs were loaded with fluorescently labelled VEGF and release kinetics were characterised. Bioactivity of unlabelled VEGF released from V-SPs was determined by analysis of embryo developmental outcomes (blastocyst developmental rate and total cell number) following individual mouse embryo culture in 20 µl of G1/G2 media at 5% oxygen, supplemented with 10 ng/ml recombinant mouse VEGF in solution or with V-SPs. The bioactivity of freeze-dried V-SPs was also assessed to determine the efficacy of cryostorage. VEGF release kinetics were characterised by an initial burst of VEGF from loaded spheres followed by a consistent lower level of VEGF release over 48 h. VEGF released from V-SPs resulted in significant increases in total blastocyst cell number relative to the control (P < 0.001), replicating the effects of medium freely supplemented with fresh VEGF (P < 0.001). Similarly, freeze dried V-SPs exerted comparable effects on embryonic development (P < 0.05). N/A. In this proof of principle study, the effects of V-SPs on embryonic development were only analysed in a mouse model. These findings suggest that SPs represent a novel method by which a targeted dose of therapeutic agents (e.g. bioactive VEGF) can be delivered to the developing in vitro embryo to promote embryonic development, an approach that negates the breakdown of VEGF associated with storage in solution. As such, V-SPs may be an alternative and effective method of delivering bioactive VEGF to the developing in vitro embryo; however, the potential use of V-SPs in clinical IVF requires further investigation. This work was funded by the University of Melbourne. The authors have no conflict of interest to declare.

Optimized culture systems for the preimplantation ICR mouse embryos with wide range of EDTA concentrations.

In this study, in vitro preimplantation embryo culture media especially for outbred stock mice (Institute of Cancer Research (ICR)) were optimized with different concentrations of ethylenediaminetetraacetic acid (EDTA). A plot with embryo development rates against EDTA concentrations ranging from 0 to 500 µM showed a unique pattern with two characteristic peaks. Two hundred micromolar was adopted as an optimal concentration of EDTA. The optimized media were also evaluated with two culture systems: conventional large volume culture system (1 ml) and micro-droplet culture system. In the conventional large volume culture system, the blastocyst development rates were compared among three different media (F-10, KSOM and KSOM with the optimized 200 µM EDTA). The rates were 0.4%, 16.7% and 57.6%, respectively. The development rates for the micro-droplet (10 µl) culture system were 73.9%. In conclusion, 200 µM EDTA concentration in 10 µl droplets in the KSOM medium was found as the most suitable culture conditions for ICR mouse embryos, as the blastocyst development rate was higher in the micro-droplet culture system than in the traditional conventional large volume culture system.