BackgroundHuman embryonic stem cells (hESCs) hold tremendous promise for cell replacement therapies for a range of degenerative diseases. In order to provide cost-effective treatments affordable by public health systems, HLA-matched allogeneic tissue banks of the highest quality clinical-grade hESCs will be required. However only a small number of existing hESC lines are suitable for clinical use; they are limited by moral and ethical concerns and none of them apply Good Manufacturing Practice (GMP) standards to the earliest and critical stages of gamete and embryo procurement. We thus aimed to derive new clinical grade hESC lines of highest quality from fresh surplus GMP grade human embryos.MethodsA comprehensive screen was performed for suitable combinations of culture media with supporting feeder cells or feeder-free matrix, at different stages, to support expansion of the inner cell mass and to establish new hESC lines.ResultsWe developed a novel two-step and sequential media system of clinical-grade hESC derivation and successfully generated seven new hESC lines of widely varying HLA type, carefully screened for genetic health, from human embryos donated under the highest ethical and moral standards under an integrated GMP system which extends from hESC banking all the way back to gamete and embryo procurement.ConclusionsThe present study, for the first time, reports the successful derivation of highest-quality clinical-grade hESC lines from fresh poor-quality surplus human embryos generated in a GMP-grade IVF laboratory. The availability of hESC lines of this status represents an important step towards more widespread application of regenerative medicine therapies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-017-0561-y) contains supplementary material, which is available to authorized users.

Mitochondria provide the major source of ATP for mammalian oocyte maturation and early embryo development. Oxygen Consumption Rate (OCR) is an established measure of mitochondrial function. OCR by mammalian oocytes and embryos has generally been restricted to overall uptake and detailed understanding of the components of OCR dedicated to specific molecular events remains lacking. Here, extracellular flux analysis (EFA) was applied to small groups of bovine, equine, mouse and human oocytes and bovine early embryos to measure OCR and its components. Using EFA, we report the changes in mitochondrial activity during the processes of oocyte maturation, fertilisation, and pre-implantation development to blastocyst stage in response to physiological demands in mammalian embryos. Crucially, we describe the real time partitioning of overall OCR to spare capacity, proton leak, non-mitochondrial and coupled respiration – showing that while activity changes over the course of development in response to physiological demand, the overall efficiency is unchanged. EFA is shown to be able to measure mitochondrial function in small groups of mammalian oocytes and embryos in a manner which is robust, rapid and easy to use. EFA is non-invasive and allows real-time determination of the impact of compounds on OCR, facilitating an assessment of the components of mitochondrial activity. This provides proof-of-concept for EFA as an accessible system with which to study mammalian oocyte and embryo metabolism.

Background Little is understood of the molecular mechanisms involved in the earliest cell fate decision in human development, leading to the establishment of the trophectoderm (TE) and inner cell mass (ICM) stem cell population. Notably, there is a lack of understanding of how transcriptional networks arise during reorganisation of the embryonic genome post-fertilisation. Results We identified a hierarchical structure of preimplantation gene network modules around the time of embryonic genome activation (EGA). Using network models along with eukaryotic initiation factor (EIF) and epigenetic-associated gene expression we defined two sets of blastomeres that exhibited diverging tendencies towards ICM or TE. Analysis of the developmental networks demonstrated stage specific EIF expression and revealed that histone modifications may be an important epigenetic regulatory mechanism in preimplantation human embryos. Comparison to published RNAseq data confirmed that during EGA the individual 8-cell blastomeres are transcriptionally primed for the first lineage decision in development towards ICM or TE. Conclusions Using multiple systems biology approaches to compare developmental stages in the early human embryo with single cell transcript data from blastomeres, we have shown that blastomeres considered to be totipotent are not transcriptionally equivalent. Furthermore we have linked the developmental interactome to individual blastomeres and to later cell lineage. This has clinical implications for understanding the impact of fertility treatments and developmental programming of long term health. Electronic supplementary material The online version of this article (10.1186/s12864-019-5558-8) contains supplementary material, which is available to authorized users.

Background: Mitochondria provide the major source of ATP for mammalian oocyte maturation and early embryo development. Oxygen Consumption Rate (OCR) is an established measure of mitochondrial function. OCR by mammalian oocytes and embryos has generally been restricted to overall uptake and detailed understanding of the components of OCR dedicated to specific molecular events remains lacking.Results: Here, extracellular flux analysis (EFA) was applied to small groups of bovine, equine, mouse and human oocytes and bovine early embryos to measure OCR. Using EFA, we report the changes in mitochondrial activity during the processes of oocyte maturation, fertilization, and pre-implantation development to blastocyst stage in response to physiological demands in mammalian embryos. Crucially, we describe the real time partitioning of overall OCR to spare capacity, proton leak, non-mitochondrial and coupled respirationshowing that while there are alterations in activity over the course of development to respond to physiological demand, the overall efficiency is unchanged.Conclusion: EFA is shown to be able to measure mitochondrial function in small groups of mammalian oocytes and embryos in a manner which is robust, rapid and easy to use. EFA is non-invasive and allows real-time determination of the impact of compounds on OCR, facilitating an assessment of the parameters of mitochondrial activity. This provides proof-ofconcept for EFA as an accessible system with which to study oocyte and embryo metabolism.

STUDY QUESTION Does the duration of embryo exposure to hyaluronic acid (HA) enriched medium improve the rate of live birth events (LBEs)? SUMMARY ANSWER The use of embryo transfer (ET) medium rich in HA improves LBE (a singleton or twin live birth) regardless of the duration of exposure evaluated in this study, but does not alter gestation or birthweight (BW). WHAT IS KNOWN ALREADY HA-enriched medium is routinely used for ET in ART to facilitate implantation, despite inconclusive evidence on safety and efficacy. STUDY DESIGN, SIZE, DURATION A cohort study was performed evaluating clinical treatment outcomes before and after HA-enriched ET medium was introduced into routine clinical practice. In total, 3391 fresh ET procedures were performed using low HA and HA-rich medium in women undergoing publicly funded IVF/ICSI treatment cycles between May 2011 and April 2015 were included in this cohort study. PARTICIPANTS/MATERIALS, SETTING, METHODS A total of 1018 ET performed using low HA medium were compared with 1198, and 1175 ET following exposure to HA-rich medium for 2–4 h (long HA exposure) or for 10–30 min (short HA exposure), respectively. A multiple logistic regression analysis was used to compare clinical outcomes including BW, gestational age and sex ratios between groups, whilst adjusting for patient age, previous attempt, incubator type and the number of embryos transferred. MAIN RESULTS AND THE ROLE OF CHANCE The use of HA-rich medium for ET was positively and significantly associated with improved clinical pregnancy rate and LBE, for both exposure durations: long HA (odds ratio (OR) = 1.21, 95% CI: 0.99–1.48), short HA (OR = 1.32, 95% CI: 1.02–1.72) and pooled OR = 1.26, 95% CI: 1.03–1.54, relative to the use of low HA medium. A comparative analysis of the risks of early pregnancy loss following long HA exposure (OR = 0.76, 95% CI: 0.54–1.06), short HA exposure (OR = 0.84, 95% CI: 0.54–1.30) and late miscarriage (OR = 0.88, 95% CI: 0.51–1.53) (OR = 1.41, 95% CI 0.72–2.77), were lower and not statistically significant. Similarly, ordinary regression analysis of the differences in BW at both HA exposures; pooled OR = −0.9 (−117.1 to 115.3), and adjusted BW between both HA cohorts; pooled OR = −13.8 (−106.1 to 78.6) did not show any differences. However, a difference in gestational age (pooled OR −0.3 (−3.4 to 2.9)) and sex ratio (pooled OR 1.43 (0.95–2.15)) were observed but these were not statistically significant relative to low HA medium. LIMITATIONS, REASONS FOR CAUTION The strength of a randomized treatment allocation was not available in this evaluation study, therefore effects of unmeasured or unknown confounding variables cannot be ruled out. WIDER IMPLICATIONS OF THE FINDINGS The result of this large cohort study strengthens the case for using HA-rich medium routinely at transfer, while adding the important clinical information that duration of exposure may not be critical. The composition and effects of commercial IVF culture media on success rate and safety remains a major controversy despite increasing calls for transparency and evidence-based practice in ART. Nonetheless, the lack of differences in BW and gestational age observed in this study were reassuring. However, an appraisal of clinical outcomes and appropriate research investigations are required for the continuous evaluation of efficacy and safety of HA. STUDY FUNDING/COMPETING INTEREST(S) T.A. is funded by a Clinical Doctoral Research Fellowship (CDRF) grant (reference: ICA-CDRF-2015-01-068) from the National Institute for Health Research (NIHR). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health. The authors declare no conflict of interest.