Cell-free fat extract improves embryo development and clinical outcomes in older women with previous in-vitro fertilization failure

BACKGROUND

Preimplantation embryos in vivo are exposed to various growth factors in the female reproductive tract that are absent in in vitro embryo culture media. Cell-free fat extract exerts antioxidant, anti-ageing, and ovarian function-promoting effects. However, its effects on embryo quality are yet to be investigated.

METHODS

We assessed the effect of cell-free fat extract supplementation on embryo culture using a naturally ageing mouse model. We assessed the model's efficacy in influencing embryo development and pregnancy rates in older women with in vitro fertilization failure. In addition, we performed immunofluorescence staining, multiplex immunoassay, whole-genome amplification and DNA sequencing, time-lapse embryo monitoring, and in vitro experiments.

RESULTS

Cell-free fat extract-supplemented media has a suitable osmolarity and pH and contains high levels of bioactive growth factors. Cell-free fat extract promoted embryo development and implantation in aged mice, probably by increasing embryo growth rate, inhibiting cell apoptosis, and promoting blastocyst adhesion. Clinical results showed that the cell-free fat extract group had significantly higher rates of the day 3 available and high-quality embryos than the control group, and the rate of usable embryos tended to be higher in the cell-free fat extract group. Furthermore, implantation and clinical pregnancy rates improved in the cell-free fat extract group than in the control group.

CONCLUSIONS

Our study implies that cell-free fat extract supplementation can promote embryo development and clinical outcomes and may serve as a rescue strategy for older women with in vitro fertilization failure.

Gestational Interrelationships among Gut-Metabolism-Transcriptome in Regulating Early Embryo Implantation and Placental Development in Mice

Decidualization of the uterine endometrium is a critical process for embryo implantation in mammals, primarily occurring on gestational day 8 in pregnant mice. However, the interplay between the maternal gut microbiome, metabolism, and the uterus at this specific time point remains poorly understood. This study employed a multi-omics approach to investigate the metabolic, gut microbiome, and transcriptomic changes associated with early pregnancy (gestational day 8 (E8)) in mice. Serum metabolomics revealed a distinct metabolic profile at E8 compared to controls, with the differential metabolites primarily enriched in amino acid metabolism pathways. The gut microbial composition showed that E8 mice exhibited higher alpha-diversity and a significant shift in beta-diversity. Specifically, the E8 group displayed a decrease in pathogenic Proteobacteria and an increase in beneficial Bacteroidetes and S24-7 taxa. Transcriptomics identified myriads of distinct genes between the E8 and control mice. The differentially expressed genes were enriched in pathways involved in alanine, aspartate, and glutamate metabolism, PI3K-Akt signaling, and the PPAR signaling pathway. Integrative analysis of the multi-omics data uncovered potential mechanistic relationships among the differential metabolites, gut microbiota, and uterine gene expression changes. Notably, the gene Asns showed strong correlations with specific gut S24-7 and metabolite L-Aspartatic acid, suggesting its potential role in mediating the crosstalk between the maternal environment and embryo development during early pregnancy. These findings provide valuable insights into the complex interplay between the maternal metabolome, the gut microbiome, and the uterine transcriptome in the context of early pregnancy, which may contribute to our understanding of the underlying mechanisms of embryo implantation and development.

Long-term health risk of offspring born from assisted reproductive technologies

Since the world's first in vitro fertilization baby was born in 1978, there have been more than 8 million children conceived through assisted reproductive technologies (ART) worldwide, and a significant proportion of them have reached puberty or young adulthood. Many studies have found that ART increases the risk of adverse perinatal outcomes, including preterm birth, low birth weight, small size for gestational age, perinatal mortality, and congenital anomalies. However, data regarding the long-term outcomes of ART offspring are limited. According to the developmental origins of health and disease theory, adverse environments during early life stages may induce adaptive changes and subsequently result in an increased risk of diseases in later life. Increasing evidence also suggests that ART offspring are predisposed to an increased risk of non-communicable diseases, such as malignancies, asthma, obesity, metabolic syndrome, diabetes, cardiovascular diseases, and neurodevelopmental and psychiatric disorders. In this review, we summarize the risks for long-term health in ART offspring, discuss the underlying mechanisms, including underlying parental infertility, epigenetic alterations, non-physiological hormone levels, and placental dysfunction, and propose potential strategies to optimize the management of ART and health care of parents and children to eliminate the associated risks. Further ongoing follow-up and research are warranted to determine the effects of ART on the long-term health of ART offspring in later life.

Effects of mycobacterium cell wall fraction on embryo development following in vitro embryo production and pregnancy rates following embryo transfer in virgin dairy heifers

An experiment was conducted to determine whether administration of mycobacterium cell wall fraction (MCWF; Amplimune, NovaVive) could enhance embryo developmental competence following in vitro embryo production (IVP) and pregnancy establishment after embryo transfer (ET). Nulliparous, Holstein heifers (n = 40; age 8-15 months) were submitted to two rounds of ovum pick-up (OPU) and IVP in a crossover design. Thirty-six h after follicle wave synchronization, treatments (saline or MCWF, 5 mL, im) were administered in conjunction with a single dose of follicle stimulating hormone (175 IU) and OPU was performed 48-52 h later. Recovered cumulus-oocyte complexes were used for IVP to assess embryo development. For ET, nulliparous, Holstein heifers (n = 225; age 12-18 months) were used as recipients. At 12-24 h after detection of spontaneous estrus, recipients were randomly treated with either saline or MCWF (5 mL, im). The effect of MCWF on pregnancy per ET (P/ET) was assessed in a 2 × 2 factorial design with recipients treated with or without MCWF receiving a fresh IVP embryo from a donor treated with or without MCWF at day 7 or 8 after detected estrus. Blood samples were collected from a subset of donors (n = 8) and recipients (n = 26 to 33 per treatment) prior to treatment and at 6 and 24 h post-treatment to determine serum concentration of interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and interferon-γ. Blood samples were also collected from a group of recipients (n = 31 to 39 per treatment) to assess serum concentration of progesterone at days 4, 7, and 16 post-treatment. Pregnancy status was determined at days 40 and 100 of gestation. Donor treatment with MCWF tended (P < 0.07) to increase the proportion of oocytes that developed into transferable embryos, but there was no effect of MCWF on other parameters of embryo development. The P/ET at days 40 and 100 of gestation and pregnancy loss were not affected by donor treatment or recipient treatment with MCWF and there was no interaction. Serum concentration of proinflammatory cytokines among donors and recipients and serum concentration of progesterone among recipients were not increased by treatment with MCWF. Results of the present study indicate that treatment of donors with MCWF has minimal impact on subsequent embryo development following IVP. Moreover, regardless of whether donors or recipients were treated with MCWF, there was no effect on P/ET following transfer of IVP embryos.

Making and selecting the best embryo in the laboratory

Over the past 4 decades our ability to maintain a viable human embryo in vitro has improved dramatically, leading to higher implantation rates. This has led to a notable shift to single blastocyst transfer and the ensuing elimination of high order multiple gestations. Future improvements to embryo culture systems will not only come from new improved innovative media formulations (such as the inclusion of antioxidants), but plausibly by moving away from static culture to more dynamic perfusion-based systems now made a reality owing to the breakthroughs in three-dimensional printing technology and micro fabrication. Such an approach has already made it feasible to create high resolution devices for intracytoplasmic sperm injection, culture, and cryopreservation, paving the way not only for improvements in outcomes but also automation of assisted reproductive technology. Although improvements in culture systems can lead to further increases in pregnancy outcomes, the ability to quantitate biomarkers of embryo health and viability will reduce time to pregnancy and decrease pregnancy loss. Currently artificial intelligence is being used to assess embryo development through image analysis, but we predict its power will be realized through the creation of selection algorithms based on the integration of information related to metabolic functions, cell-free DNA, and morphokinetics, thereby using vast amounts of different data types obtained for each embryo to predict outcomes. All of this will not only make assisted reproductive technology more effective, but it will also make it more cost effective, thereby increasing patient access to infertility treatment worldwide.

Detrimental actions of obesity-associated advanced glycation end-products on endometrial epithelial cell proliferation are alleviated by antioxidants

RESEARCH QUESTION

Advanced glycation end-products (AGE) are elevated in the uterine environment of obese infertile women. Can the detrimental effects of AGE on endometrial epithelial cells be mitigated with therapeutics, and recapitulated in a more physiologically relevant primary model (organoids)?

DESIGN

Human endometrial epithelial cells (ECC-1) were exposed to AGE at concentrations physiologically representative of uterine fluid in lean or obese individuals, and three potential therapeutics: 25 nmol/l receptor for AGE (RAGE) antagonist FPS-ZM1, 100 μmol/l metformin, or a combination of antioxidants (10 μmol/l N-acetyl-l-cysteine, 10 μmol/l N-acetyl-l-carnitine and 5 μmol/l α-lipoic acid). Real-time cell analysis (xCELLigence, ACEA Biosciences) determined the rate of adhesion and proliferation. The proliferation of organoid-derived cells and secretion of cytokines from organoids was characterized in the presence of AGE (n = 5). The uterine fluid of women undergoing assisted reproduction was profiled for AGE-associated inflammatory markers (n = 77).

RESULTS

ECC-1 proliferation was reduced by AGE from obese versus lean conditions and vehicle control (P = 0.04 and P < 0.001, respectively), and restored to a proliferation corresponding to lean conditions by antioxidants. AGE influenced organoid derived primary endometrial epithelial cell proliferation in a donor-dependent manner. AGE increased the organoid secretion of the proinflammatory cytokine CXCL16 (P = 0.006). Clinically, CXCL16 correlated positively to maternal body mass index (R = 0.264, P = 0.021) and intrauterine glucose concentration (R = 0.736, P < 0.0001).

CONCLUSIONS

Physiologically relevant concentrations of AGE alter endometrial epithelial cell function. Antioxidants restore the rate of proliferation of AGE-treated endometrial epithelial (ECC-1) cells. Primary endometrial epithelial cells, cultured as organoids, demonstrate altered proliferation and CXCL16 secretion in the presence of AGE equimolar with the uterine fluid from obese individuals.

GM-CSF perturbs cell identity in mouse pre-implantation embryos

Growth factors became attractive candidates for medium supplementation to further improve the quality of embryo culture and to mimic in vivo nutrition. Granulocyte macrophage colony-stimulating factor (GM-CSF) is a cytokine influencing the maternal-fetal interface and supporting placental development in mouse and human. It is expressed in epithelial cells of the endometrium under the regulation of estrogens. The factor is already in clinical use and a large clinical trial showed that, if supplemented to an embryo culture medium, it leads to increased survival of embryos, especially in women with previous miscarriages. Animal and cell culture studies on isolated trophectoderm cells support an effect mainly on cellular expansion. Aim of this study was to investigate, if the supplementation of GM-CSF either in a human ART medium or in a mouse optimized medium, leads to a change in cell number and cell lineages in the early pre-implantation mouse embryo. Our data shows that mouse GM-CSF increased total cell numbers with increasing concentrations. This increase of cell number has not been found in embryos cultured in ART media with or without human GM-CSF (hGM-CSF) or in a mouse medium supplemented with different concentrations of hGM-CSF. The changes were caused by a marked difference in TE and primitive endoderm cell numbers but not due to a change in epiblast cell numbers. Additionally, results show an ectopic expression of NANOG among trophectoderm cells in both, human ART media (with and without GM-CSF) and at increasing concentrations in the mouse and the human GM-CSF supplemented media. In conclusion, we could show that GM-CSF has an effect on cell identity in mice, which might probably also occur in the human. Therefore, we would like to rare awareness that the use of supplements without proper research could bare risks for the embryo itself and probably also in the post-implantation phase.

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

STUDY QUESTION

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?

SUMMARY ANSWER

Supplementation of embryo culture media with V-SPs promoted embryonic development in a manner equivalent to media supplemented with free VEGF.

WHAT IS KNOWN ALREADY

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.

STUDY DESIGN, SIZE, DURATION

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).

PARTICIPANTS/MATERIALS, SETTING, METHODS

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.

MAIN RESULTS AND THE ROLE OF CHANCE

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).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

In this proof of principle study, the effects of V-SPs on embryonic development were only analysed in a mouse model.

WIDER IMPLICATIONS OF THE FINDINGS

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.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by the University of Melbourne. The authors have no conflict of interest to declare.