Use of a mouse in vitro fertilization model to understand the developmental origins of health and disease hypothesis

Metabolic regulation of preimplantation embryo development in vivo and in vitro: Molecular mechanisms and insights

Understanding of embryonic development has led to the clinical application of Assisted Reproductive technologies (ART), with the resulting birth of millions of children. Recent developments in metabolomics, proteomics, and transcriptomics have brought to light new insights into embryonic growth dynamics, with implications spanning reproductive medicine, stem cell research, and regenerative medicine. The review explores the key metabolic processes and molecular pathways active during preimplantation embryo development, including PI3K-Akt, mTOR, AMPK, Wnt/β-catenin, TGF-β, Notch and Jak-Stat signaling pathways. We focused on analyzing the differences occurring in vitro as opposed to in vivo development and we discussed significant physiological and clinical implications.

Bridging the Gap: Animal Models in Next-Generation Reproductive Technologies for Male Fertility Preservation

This review aims to explore advanced reproductive technologies for male fertility preservation, underscoring the essential role that animal models have played in shaping these techniques through historical contexts and into modern applications. Rising infertility concerns have become more prevalent in human populations recently. The surge in male fertility issues has prompted advanced reproductive technologies, with animal models playing a pivotal role in their evolution. Historically, animal models have aided our understanding in the field, from early reproductive basic research to developing techniques like artificial insemination, multiple ovulation, and in vitro fertilization. The contemporary landscape of male fertility preservation encompasses techniques such as sperm cryopreservation, testicular sperm extraction, and intracytoplasmic sperm injection, among others. The relevance of animal models will undoubtedly bridge the gap between traditional methods and revolutionary next-generation reproductive techniques, fortifying our collective efforts in enhancing male fertility preservation strategies. While we possess extensive knowledge about spermatogenesis and its regulation, largely thanks to insights from animal models that paved the way for human infertility treatments, a pressing need remains to further understand specific infertility issues unique to humans. The primary aim of this review is to provide a comprehensive analysis of how animal models have influenced the development and refinement of advanced reproductive technologies for male fertility preservation, and to assess their future potential in bridging the gap between current practices and cutting-edge fertility techniques, particularly in addressing unique human male factor infertility.

Maternal contributions to pregnancy success: from gamete quality to uterine environment

The establishment and maintenance of a pregnancy that goes to term is sine qua non for the long-term sustainability of dairy and beef cattle operations. The oocyte plays a critical role in providing the factors necessary for preimplantation embryonic development. Furthermore, the female, or maternal, environment where oocytes and embryos develop is crucial for the establishment and maintenance of a pregnancy to term. During folliculogenesis, the oocyte must sequentially acquire meiotic and developmental competence, which are the results of a series of molecular events preparing the highly specialized gamete to return to totipotency after fertilization. Given that folliculogenesis is a lengthy process in the cow, the occurrence of disease, metabolic imbalances, heat stress, or other adverse events can make it challenging to maintain oocyte quality. Following fertilization, the newly formed embryo must execute a tightly planned program that includes global DNA remodeling, activation of the embryonic genome, and cell fate decisions to form a blastocyst within a few days and cell divisions. The increasing use of assisted reproductive technologies creates an additional layer of complexity to ensure the highest oocyte and embryo quality given that in vitro systems do not faithfully recreate the physiological maternal environment. In this review, we discuss cellular and molecular factors and events known to be crucial for proper oocyte development and maturation, as well as adverse events that may negatively affect the oocyte; and the importance of the uterine environment, including signaling proteins in the maternal-embryonic interactions that ensure proper embryo development. We also discuss the impact of assisted reproductive technologies in oocyte and embryo quality and developmental potential, and considerations when looking into the prospects for developing systems that allow for in vitro gametogenesis as a tool for assisted reproduction in cattle.

The mammalian preimplantation embryo: Its role in the environmental programming of postnatal health and performance

During formation of the preimplantation embryo several cellular and molecular milestones take place, making the few cells forming the early embryo vulnerable to environmental stressors than can impair epigenetic reprogramming and controls of gene expression. Although these molecular alterations can result in embryonic death, a significant developmental plasticity is present in the preimplantation embryo that promotes full-term pregnancy. Prenatal epigenetic modifications are inherited during mitosis and can perpetuate specific phenotypes during early postnatal development and adulthood. As such, the preimplantation phase is a developmental window where developmental programming can take place in response to the embryonic microenvironment present in vivo or in vitro. In this review, the relevance of the preimplantation embryo as a developmental stage where offspring health and performance can be programmed is discussed, with emphasis on malnutrition and assisted reproductive technologies; two major environmental insults with important implications for livestock production and human reproductive medicine.

Body composition as an indicator of metabolic changes in mice obtained by in vitro fertilization

To identify body systems subject to epigenetic transformation during in vitro fertilization (IVF), comparative morphological and functional studies were performed on sexually mature offspring of outbred CD1 mice, specific-pathogen-free (SPF), obtained by IVF (experiment) and natural conception (control). The studies included assessment of age-related changes in body weight and composition, energy intake and expenditure, and glucose homeostasis. To level the effects caused by the different number of newborns in the control and in the experiment, the size of the fed litters was halved in the control females. Males obtained using the IVF procedure were superior in body weight compared to control males in all age groups. As was shown by analysis of variance with experiment/control factors, gender, age (7, 10 and 20 weeks), the IVF procedure had a statistically significant and unidirectional effect on body composition. At the same time, IVF offspring outperformed control individuals in relative fat content, but were behind in terms of lean mass. The effect of the interaction of factors was not statistically significant. IVF offspring of both sexes had higher fat to lean mass ratios (FLR). Since adipose tissue contributes significantly less to total energy intake compared to muscle, the main component of lean mass, it is not surprising that at the same level of IVF locomotor activity offspring consumed less food than controls. When converted to one gram of body weight, this difference reached 19 %. One of the consequences of reduced utilization of IVF energy substrates by offspring is a decrease in their tolerance to glucose loading. The integral criterion for the effectiveness of restoring the initial glucose level is the area under the curve (AUC), the value of which was 2.5 (males) and 3.2 (females) times higher in IVF offspring compared to the corresponding control. Thus, the totality of our original and literature data shows an increase in the risk of metabolic disorders in IVF offspring, which is confirmed by epidemiological studies of a relatively young cohort of people born using assisted reproductive technologies.

Metabolomic Profile of Children Conceived With Medically Assisted Technologies

CONTEXT

Assisted reproductive technologies (ART) and non-in vitro fertilization fertility treatments (NIFT) are treatments for infertility. These technologies may have long-term health effects in children such as increased hypertension, glucose intolerance, and hypertriglyceridemia. Few studies have compared children born following ART and NIFT to those conceived spontaneously by subfertile couples.

OBJECTIVE

This work aimed to describe metabolic differences in children conceived by ART and NIFT compared to children conceived spontaneously by infertile couples.

METHODS

Children conceived by parent(s) receiving infertility care at the University of California, San Francisco, between 2000 and 2017 were invited to participate in the Developmental Epidemiological Study of Children born through Reproductive Technology (DESCRT). Serum metabolomic analyses were conducted using samples from 143 enrolled children (age range 4-12 years, 43% female) conceived using NIFT or ART (with fresh or frozen embryos with and without intracytoplasmic sperm injection [ICSI]) and children conceived spontaneously by subfertile couples. Principal component analysis and multivariable regression were used to compare the distribution of metabolites between groups.

RESULTS

There was no separation in metabolites based on treatment or sex. NIFT-conceived children showed no differences compared to spontaneously conceived controls. Only spontaneously conceived children had different metabolomics profiles from children conceived from fresh ART, frozen ART, and all ICSI. Pantoate and propionylglycine levels were elevated in fresh ART compared to the spontaneous group (P < .001). Propionylglycine levels were elevated in the ICSI (both fresh and frozen) vs the spontaneous group (P < .001). Finally, 5-oxoproline levels were decreased in frozen ART compared to the spontaneous group (P < .001).

CONCLUSION

NIFT-conceived children did not show any metabolic differences compared with spontaneously conceived children. The metabolic differences between ART-conceived children and children conceived spontaneously were small but unlikely to be clinically significant but should be examined in future studies.

Offspring physiology following the use of IVM, IVF and ICSI: a systematic review and meta-analysis of animal studies

BACKGROUND

Since the birth of the first baby using IVF technology in 1978, over 10 million children have been conceived via ART. Although most aspects of ARTs were developed in animal models, the introduction of these technologies into clinical practice was performed without comprehensive assessment of their long-term safety. The monitoring of these technologies over time has revealed differences in the physiology of babies produced using ARTs, yet due to the pathology of those presenting for treatment, it is challenging to separate the cause of infertility from the effect of treatments offered. The use of systematic review and meta-analysis to investigate the impacts of the predominant ART interventions used clinically in human populations on animals produced in healthy fertile populations offers an alternative approach to understanding the long-term safety of reproductive technologies.

OBJECTIVE AND RATIONALE

This systematic review and meta-analysis aimed to examine the evidence available from animal studies on physiological outcomes in the offspring conceived after IVF, IVM or ICSI, compared to in vivo fertilization, and to provide an overview on the landscape of research in this area.

SEARCH METHODS

PubMed, Embase and Commonwealth Agricultural Bureaux (CAB) Abstracts were searched for relevant studies published until 27 August 2021. Search terms relating to assisted reproductive technology, postnatal outcomes and mammalian animal models were used. Studies that compared postnatal outcomes between in vitro-conceived (IVF, ICSI or IVM) and in vivo-conceived mammalian animal models were included. In vivo conception included mating, artificial insemination, or either of these followed by embryo transfer to a recipient animal with or without in vitro culture. Outcomes included birth weight, gestation length, cardiovascular, metabolic and behavioural characteristics and lifespan.

OUTCOMES

A total of 61 studies in five different species (bovine, equine, murine, ovine and non-human primate) met the inclusion criteria. The bovine model was the most frequently used in IVM studies (32/40), while the murine model was mostly used in IVF (17/20) and ICSI (6/8) investigations. Despite considerable heterogeneity, these studies suggest that the use of IVF or maturation results in offspring with higher birthweights and a longer length of gestation, with most of this evidence coming from studies in cattle. These techniques may also impair glucose and lipid metabolism in male mice. The findings on cardiovascular outcomes and behaviour outcomes were inconsistent across studies.

WIDER IMPLICATIONS

Conception via in vitro or in vivo means appears to have an influence on measurable outcomes of offspring physiology, manifesting differently across the species studied. Importantly, it can be noted that these measurable differences are noticeable in healthy, fertile animal populations. Thus, common ART interventions may have long-term consequences for those conceived through these techniques, regardless of the pathology underpinning diagnosed infertility. However, due to heterogeneous methods, results and measured outcomes, highlighted in this review, it is difficult to draw firm conclusions. Optimizing animal and human studies that investigate the safety of new reproductive technologies will provide insight into safeguarding the introduction of novel interventions into the clinical setting. Cautiously prescribing the use of ARTs clinically may also be considered to reduce the chance of promoting adverse outcomes in children conceived before long-term safety is confidently documented.

Effects of assisted reproductive technology on gene expression in heart and spleen tissues of adult offspring mouse

OBJECTIVES

Assisted reproductive technology (ART) is an important part of reproductive medicine, whose possible effects on offspring's health have drawn widespread attention in recent years. However, relevant studies are limited to postnatal short-term follow-up and lack of diverse sample sources analysis other than blood.

METHODS

In this study, a mouse model was used to explore the effects of ART on fetal development and gene expression in the organs of offspring in the adulthood using next-generation sequencing. The sequencing results were then analyzed.

RESULTS

The results showed that it caused abnormal expression in 1060 genes and 179 genes in the heart and spleen, respectively. Differentially expressed genes (DEGs) in the heart are mainly enriched in RNA synthesis and processing, and the cardiovascular system development also shows enrichment. STRING analysis identified Ccl2, Ptgs2, Rock1, Mapk14, Agt, and Wnt5a as the core interacting factors. DEGs in the spleen are significantly enriched in anti-infection and immune responses, which include the core factors Fos, Jun and Il1r2. Further exploration revealed the abnormal expression of 42 and 5 epigenetic modifiers in the heart and spleen, respectively. The expression of the imprinted genes Dhcr7, Igf2, Mest and Smoc1 decreased in the hearts of ART offspring, and the DNA methylation levels of Igf2- and Mest-imprinting control regions (ICRs) increased abnormally.

CONCLUSION

In the mouse model, ART can interfere with the gene expression pattern in the heart and spleen of the adult offspring and that these changes are related to the aberrant expression of epigenetic regulators.

GDF15 negatively regulates RGS16 to impair hepatic lipid metabolism in male mice offspring conceived by in vitro fertilization

OBJECTIVES

We generated an in vitro fertilization and embryo transfer (IVF-ET) mouse model to investigate the molecular mechanism underlying the abnormal lipid metabolism found in IVF-ET offspring.

METHODS

The glucose metabolism levels of offspring were assessed by glucose tolerance test (GTT), insulin tolerance test (ITT), and pyruvate tolerance test (PTT). The lipid metabolism levels were assessed by triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C). RNA-seq was performed on liver tissues. mRNA and protein expression of relevant genes was verified by the quantitative real-time PCR and protein immunoblotting. HepG2 cells were transfected with either interfering RNA or overexpression plasmids to investigate the gene functions.

RESULTS

Compared to the control, male IVF-ET offspring showed: 1) higher body, liver, and epididymal white adipose tissue weight; 2) disrupted glucolipid metabolism with abnormal GTT, ITT, and PTT; 3) significantly decreased GDF15 along with increased RGS16. Furthermore, phosphorylation of ERK1/2 and AKT was significantly reduced. In HepG2 cells, knockdown of GDF15 caused an abnormally increased RGS16 and decreased phosphorylation of ERK1/2 and AKT, accompanied by increased lipid deposition. In contrast, overexpression of GDF15 reduced expression of RGS16. Simultaneous knockdown of both GDF15 and RGS16 reversed lipid deposition.

CONCLUSIONS

Down-regulation of GDF15 results in elevated RGS16, which causes the weakening of the downstream ERK1/2 and AKT phosphorylation, leading to abnormal lipid metabolism in the livers of IVF-ET male offspring. This suggests that the GDF15-RGS16-p-ERK1/2/p-AKT pathway plays a crucial role in liver lipid deposition in IVF-ET male offspring and could be a therapeutic target.

Mitochondrial function and intracellular distribution is severely affected in in vitro cultured mouse embryos

Studies of mitochondrial dynamics have identified an intriguing link between energy supply balance and mitochondrial architecture. This suggests that inappropriate culture conditions might inhibit mitochondrial functions, and affect embryonic development. Therefore, this study was conducted to determine whether in vitro culture (IVC) might affect mitochondrial function, distribution, organization (by Mitotracker Green), gene expression on RNA level (by qPCR), and protein expression and localization (by western blot and immunostaining) involved in regulation of mitochondrial functions. Mitochondria in 2-cell IVC embryos were less numerous compare to IN VIVO while the localization and distribution do not differ between the groups. Mitochondria of in vivo blastocysts formed elongated network along the cells, while in IVC were fragmented, rounded, and aggregated mainly in the perinuclear region. Additionally, mitochondria of IN VIVO embryos moved back and forth along their long axis on radial tracks, while in IVC blastocysts were much less active. mtDNA copy number in IVC blastocysts (92,336.65 ± 5860.04) was significantly lower than that of IN VIVO (169,103.92 ± 16,322.41; P < 0.02) as well as lower protein expressions responsible for mitochondrial fusion was observed in IVC blastocysts. Results indicate that in vitro culture affect on perturbations in mitochondrial number and function, which is associated with decreased developmental competence of in vitro produced mouse embryos.

Murine blastocysts generated by in vitro fertilization show increased Warburg metabolism and altered lactate production

In vitro fertilization (IVF) has resulted in the birth of over 8 million children. Although most IVF-conceived children are healthy, several studies suggest an increased risk of altered growth rate, cardiovascular dysfunction, and glucose intolerance in this population compared to naturally conceived children. However, a clear understanding of how embryonic metabolism is affected by culture condition and how embryos reprogram their metabolism is unknown. Here, we studied oxidative stress and metabolic alteration in blastocysts conceived by natural mating or by IVF and cultured in physiologic (5%) or atmospheric (20%) oxygen. We found that IVF-generated blastocysts manifest increased reactive oxygen species, oxidative damage to DNA/lipid/proteins, and reduction in glutathione. Metabolic analysis revealed IVF-generated blastocysts display decreased mitochondria respiration and increased glycolytic activity suggestive of enhanced Warburg metabolism. These findings were corroborated by altered intracellular and extracellular pH and increased intracellular lactate levels in IVF-generated embryos. Comprehensive proteomic analysis and targeted immunofluorescence showed reduction of lactate dehydrogenase-B and monocarboxylate transporter 1, enzymes involved in lactate metabolism. Importantly, these enzymes remained downregulated in the tissues of adult IVF-conceived mice, suggesting that metabolic alterations in IVF-generated embryos may result in alteration in lactate metabolism. These findings suggest that alterations in lactate metabolism are a likely mechanism involved in genomic reprogramming and could be involved in the developmental origin of health and disease.

Altered Expression of Pulmonary Epithelial Cell Markers in Fetal and Adult Mice Generated by in vitro Embryo Culture and Embryo Transfer

Lung development is impaired in mice generated through transfer of in vitro-derived blastocysts. The main objective of the current study was to determine if the composition of epithelial cells in the fetal and adult lung tissue is altered in mice generated through transfer of in vitro-derived blastocysts. The study comprised two experimental (EGs) and two control (CGs) groups. Fetuses (18.5 d.p.c.) and adult mice (8 weeks old) of the EGs (EGfetus, n = 18; EGadult, n = 15) were produced by the transfer of day 5 F2 blastocysts to pseudo-pregnant females. F2 fetuses and adult mice derived from naturally ovulating females served as the CGs (CGfetus, n = 18; CGadult, n = 15). The expression of Tuba-1a (a marker of ciliated cells), Foxj-1 (a marker of motile ciliated cells), Uch-L1 (a marker of neuroendocrine cells), Cldn-10 (a marker of club cells), Aqp-5 (a marker of type I alveolar cells), and Sp-C (a marker of type II alveolar cells) was determined using Western blot, immunohistochemistry/immunofluorescence, and quantitative RT-PCR analyses. Weight of fetuses as well as adult mice is decreased in mice comprising the EGs. Impaired lung development observed in EGfetus was associated with altered expression of Tuba-1a, Foxj-1, Cldn-10, Uch-L1, Sp-C, and Aqp-5. Morphology of the adult lung tissue was similar between the groups except for a significant increase in the thickness of the epithelia in EGadult. The expression of Cldn-10 and Sp-C was also altered in EGadult. It remains to be determined whether altered expression of these genes has any long-term impact on epithelial cell functions in the adult lung tissue.

miR-17-5p in bovine oviductal fluid affects embryo development

This study identified microRNAs (miRNAs) in bovine oviductal fluids (OFs) and examined the effect of miR-17-5p in OFs on embryonic development to the blastocyst stage. Small RNA-seq of extracellular vesicles of OFs revealed 242 miRNAs. Additionally, analyzing expressions of randomly selected OF-miRNAs with RT-qPCR in the culture medium of oviductal epithelial cells indicated that the abundance of miRNAs in OFs increased during the luteal phase. miR-17-5p mimic-treated eight-cell-stage zona pellucida-free embryos showed improved embryonic development to the blastocyst stage. The effect of the miR-17-5p mimic was confirmed using a dual-luciferase assay and immunostaining. In addition, RNA-seq of the miR-17-5p mimic- or control-treated embryos revealed differentially expressed genes (DEGs), suggesting possible pathways that overlapped with the in silico-predicted pathways for miR-17-5p targeting genes. Furthermore, ingenuity pathway analysis of DEG predicted miR-17 to be a significant upstream regulator. Our results suggest that miR-17-5p in OFs regulates embryonic development in bovines.

Small Noncoding RNAs Contribute to Sperm Oxidative Stress-Induced Programming of Behavioral and Metabolic Phenotypes in Offspring

There is growing evidence that paternal environmental information alters small noncoding RNAs (sncRNAs) in sperm and in turn can induce alterations of metabolic and behavioral phenotypes of the next generation. However, the potential mediators of the effects remain to be elucidated. A great diversity of environmental insults and stresses can convergently induce the elevation of reactive oxygen species (ROS) in sperm; nonetheless, it remains unclear whether ROS mediates the biogenesis of sncRNAs in sperm and participates in the reprogramming of offspring phenotypes. Here, we show that ROS could induce the alteration of sncRNA profiles in sperm, especially for transfer RNA-derived small RNAs (tsRNAs) and ribosomal RNA-derived small RNAs (rsRNAs). Zygotic injection of 29-34 nt RNA fractions (predominantly tsRNAs and rsRNAs) from oxidative stress (OS) sperm could induce depressive-like and anxiety-like behaviors in male offspring. Moreover, zygotic injection with synthetic RNAs partially resembled OS sperm-induced depressive-like and anxiety-like behaviors in offspring. Male offspring maintained on a chow diet was found to develop impaired glucose tolerance and hyperactive hepatic gluconeogenesis, accompanied by the upregulation of hepatic gluconeogenic and lipolytic genes. Together, our results have shown that ROS-induced alteration of sncRNA profiles in sperm contributes to the alterations of behavioral and metabolic phenotypes of the offspring.

Comparative analysis of histone H3K27me3 modifications between blastocysts and somatic tissues in cattle

Epigenetic modifications established in the early developmental stages can have long-term consequences throughout life. This concept encompasses the possibility of controlling livestock health and diseases by epigenetic regulation during early development. To explore the candidates of epigenetic modifications in early embryos that might exert long-lasting effects in adulthood, we aimed to obtain genome-wide histone H3 lysine 27 trimethylation (H3K27me3) profiles of bovine blastocysts and compare these data with those from adult somatic tissues in order to extract common and typical features between them. Bovine blastocysts were produced in vitro and subjected to chromatin immunoprecipitation-sequencing analysis of H3K27me3. Comparative analysis of the blastocyst-derived H3K27me3 profile performed using publicly available data from adult muscle, fat, and liver tissues revealed that (1) blastocyst-specific modifications against somatic tissues were enriched in immune function-related genes, (2) somatic modifications "sieved" by blastocyst modifications were enriched in biological processes in tissue-specific trends, (3) the modifications common in blastocyst and each somatic tissue were largely overlapped and enriched in developmentally important genes, including homeobox and imprinted genes. The results of this study produced a genome-wide H3K27me3 profile of bovine blastocysts and revealed its common and typical features in relation to the profiles of adult somatic tissues.

Melatonin supplementation in the culture medium rescues impaired glucose metabolism in IVF mice offspring

Increasing evidence suggests that in vitro fertilization (IVF) may be associated with an increased risk of developing obesity and metabolic diseases later in life in the offspring. Notably, the addition of melatonin to culture medium may improve embryo development and prevent cardiovascular dysfunction in IVF adult mice. This study aimed to determine if melatonin supplementation in the culture medium can reverse impaired glucose metabolism in IVF mice offspring and the underlying mechanisms. Blastocysts used for transfer were generated by natural mating (control group) or IVF with or without melatonin (10^-6  M) supplementation (mIVF and IVF group, respectively) in clinical-grade culture media. Here, we first report that IVF decreased hepatic expression of Fbxl7, which was associated with impaired glucose metabolism in mice offspring. Melatonin addition reversed the phenotype by up-regulating the expression of hepatic Fbxl7. In vitro experiments showed that Fbxl7 enhanced the insulin signaling pathway by degrading RhoA through ubiquitination and was up-regulated by transcription factor Foxa2. Specific knockout of Fbxl7 in the liver of adult mice, through tail intravenous injection of recombinant adeno-associated virus, impaired glucose tolerance, while overexpression of hepatic Fbxl7 significantly improved glucose tolerance in adult IVF mice. Thus, the data suggest that Fbxl7 plays an important role in maintaining glucose metabolism of mice, and melatonin supplementation in the culture medium may rescue the long-term risk of metabolic diseases in IVF offspring.

How the environment affects early embryonic development

In the field of animal reproduction, the environment associated with gametes and embryos refers to the parents' condition as well as conditions surrounding gametes and embryos in vivo or in vitro . This environment is now known to influence not only the functionality of the early embryo but potentially the future phenotype of the offspring. Using transcriptomic and epigenetic molecular analysis, and the bovine model, recent research has shown that both the female and the male metabolic status, for example age, can affect gene expression and gene programming in the embryo. Evidence demonstrates that milking cows, which are losing weight at the time of conception, generates compromised embryos and offspring with a unique metabolic signature. A similar phenomenon has been associated with different culture conditions and the IVF procedure. The general common consequence of these situations is an embryo behaving on 'economy' mode where translation, cell division and ATP production is reduced, potentially to adapt to the perceived future environment. Few epidemiological studies have been done in bovines to assess if these changes result in a different phenotype and more studies are required to associate specific molecular changes in embryos with visible consequences later in life.

Early Embryo Exposure to Assisted Reproductive Manipulation Induced Subtle Changes in Liver Epigenetics with No Apparent Negative Health Consequences in Rabbit

Embryo manipulation is a requisite step in assisted reproductive technology (ART). Therefore, it is of great necessity to appraise the safety of ART and investigate the long-term effect, including lipid metabolism, on ART-conceived offspring. Augmenting our ART rabbit model to investigate lipid metabolic outcomes in offspring longitudinally, we detected variations in hepatic DNA methylation ART offspring in the F3 generation for embryonic exposure (multiple ovulation, vitrification and embryo transfer). Through adult liver metabolomics and proteomics, we identified changes mainly related to lipid metabolism (e.g., polyunsaturated fatty acids, steroids, steroid hormone). We also found that DNA methylation analysis was linked to changes in lipid metabolism and apoptosis genes. Nevertheless, these differences did not apparently alter the general health status. Thus, our findings suggest that ART is likely to be a player in embryo epigenetic events related to hepatic homeostasis alteration in adulthood.

Perturbations of the hepatic proteome behind the onset of metabolic disorders in mouse offspring developed following embryo manipulation

Assisted Reproductive Technologies (ART) allowed the births of >8 million babies worldwide. Even if ART children are healthy at birth, several studies reported that ART may cause changes in foetal programming, leading to an increased predisposition to metabolic disorders in adulthood. Previous studies on mouse model showed obesity, glucose intolerance, and hepatic lipid accumulation in ART offspring. A cumulative effect of the different components of ART protocol has been previously described, for example, in the occurrence of epigenetic defects. Here, we investigated whether there is a cumulative effect of embryo transfer (ET), in vitro culture (IVC) and blastomere biopsy (BB) in the onset of metabolic disorders in mouse offspring vs those naturally conceived (Control - CTR). To this aim, proteomic analysis was performed on the livers from adult mouse offspring developed following ET, IVC and BB vs CTR. We observed deregulated expression of proteins involved in lipid, carbohydrate, energy metabolisms and cellular processes in ART offspring. Moreover, we found increased body weight in all ART offspring while i) insulin resistance in BB male, ii) females glucose intolerance and high level of triglycerides and cholesterol in BB females and iii) low levels of interleukin-6 in BB, IVC and ET males. In conclusion, our study suggests that the use of various embryo manipulations influences the metabolic health of adult offspring, resulting in an increased predisposition to hepatic diseases and metabolic syndrome in a sex-specific manner.

Epigenomic and transcriptomic analyses reveal early activation of the HPG axis in in vitro-produced male dairy calves

In cattle, several calves born after IVP ("in vitro" embryo production) present similar birthweight to those generated after MOET (multiple ovulation and embryo transfer). However, the underlying molecular patterns in organs involved in the developmental process are unknown and could indicate physiological programming. The objectives of this study were: (1) to compare epigenomic and transcriptomic modifications in the hypothalamus, pituitary, gonadal and adrenal organs between 3 months old ovum pick-up-IVP and MOET male calves (n = 4 per group) and (2) to use blood epigenomic data to proxy methylation of the inner organs. Extracted gDNA and RNA were sequenced through whole-genome bisulfite sequencing and RNA sequencing, respectively. Next, bioinformatic analyses determined differentially methylated cytosines (DMC) and differentially expressed genes (DEG) (FDR < 0.05) in IVP versus MOET samples and the KEGG pathways that were overrepresented by genes associated with DMC or DEG (FDR < 0.1). Pathways related to hypothalamus, pituitary, gonadal (HPG) axis activation (GnRH secretion in the hypothalamus, GnRH signaling in the pituitary, and steroidogenesis in the testicle) were enriched in IVP calves. Modeling the effect of the methylation levels and the group on the expression of all the genes involved in these pathways confirmed their upregulation in HPG organs in IVP calves. The application of the DIABLO method allowed the identification of 15 epigenetic and five transcriptomic biomarkers, which were able to predict the embryo origin using the epigenomic data from the blood. In conclusion, the use of an integrated epigenomic-transcriptomic approach suggested an early activation of the HPG axis in male IVP calves compared to MOET counterparts, and the identification of potential biomarkers allowed the use of blood samples to proxy methylation levels of the relevant internal organs.

Ovulation induction is associated with altered growth but with preservation of normal metabolic function in murine offspring

OBJECTIVE

To study the effects of ovulation induction on mouse postnatal health, with a focus on growth pattern and glucose tolerance. To study the effect of ovulation induction on DNA methylation, we took advantage of the agouti viable yellow (Avy) mouse.

DESIGN

Animal study.

SETTING

University Setting.

ANIMALS

Agouti viable yellow (Avy) mice on a C57BL/6 background.

INTERVENTION(S)

Avy female mice were either allowed to mate spontaneously (control group, C) or after superovulation with 5 IU of PMSG and hCG (ovulation induction group, OI).

MAIN OUTCOME MEASURE(S)

Birth parameters and postnatal growth of the offspring were followed up to 29 weeks of age. Body composition analysis was performed by EchoMRI; fasting insulin, intraperitoneal glucose tolerance tests, and glucose-stimulated insulin secretion by beta cells were assessed to study glucose metabolism.

RESULT(S)

Mice born to superovulated dams had lower survival rates, shorter anogenital distances, and shorter crown-rump lengths. Female mice generated by OI weighed less at birth, whereas male mice generated by OI had lower weight gain and had reduced lean mass. Glucose parameters, including islet functions, did not differ between the groups. No difference in agouti coat color was noted between the groups.

CONCLUSION(S)

Ovulation induction resulted in mice having increased morphometric differences at birth and male mice showing reduced weight gain but no difference in glucose tolerance or agouti coat color.

Sex-specific effects of in vitro fertilization on adult metabolic outcomes and hepatic transcriptome and proteome in mouse

Although in vitro fertilization (IVF) is associated with adverse perinatal outcomes, there is increasing concern about the long-term and sex-specific health implications. Augmenting our IVF mouse model to longitudinally investigate metabolic outcomes in offspring from optimal neonatal litter sizes, we found sex-specific metabolic outcomes in IVF offspring. IVF-conceived females had higher body weight and cholesterol levels compared to naturally conceived females, whereas IVF-conceived males had higher levels of triglycerides and insulin, and increased body fat composition. Through adult liver transcriptomics and proteomics, we identified sexually dimorphic dysregulation of the sterol regulatory element-binding protein (SREBP) pathways that are associated with the sex-specific phenotypes. We also found that global loss of DNA methylation in placenta was linked to higher cholesterol levels in IVF-conceived females. Our findings indicate that IVF procedures have long-lasting sex-specific effects on metabolic health of offspring and lay the foundation to utilize the placenta as a predictor of long-term outcomes.

Enhanced Synergistic-Antioxidant Activity of Melatonin and Tretinoin by Co-encapsulation into Amphiphilic Chitosan Nanocarriers: During Mice In Vitro Matured Oocyte/Morula-Compact Stage Embryo Culture Model

The use of exogenous antioxidants or the combination of them during in vitro oocyte/embryo culture media is reasonable. Co-delivery by nanocarrier has been designed to overcome the limitations of combining them traditionally. In this work, amphiphilic chitosan nanocarrier (ACN) was applied to co-encapsulate melatonin (Mel) and tretinoin (TTN) by the self-assembled method and evaluate their synergistic antioxidant efficacy in mice oocytes/embryos. The formation of single/dual-ACN was confirmed by Fourier-transformed infrared spectroscopy (FT-IR). The average particle diameter, size distribution, polydispersity index (PDI), and zeta potential of them were measured by dynamic light scattering (DLS), and the morphology was evaluated by TEM and SEM technologies. Also, the encapsulation efficiency (EE%) and drug loading content (DL%) of the nanocapsules were determined by UV-vis spectrophotometry. Studies of the in vitro release showed a continued drug release without any bursting effect of Mel+TTN-ACNs compared with single Mel/TTN-ACNs. Then, in both experiments, nuclear staining (Aceto-orcein and Hoechst 33342), fluorescent staining of H2DCFDA, chemiluminescence test, and qRT-PCR technique were performed as in vitro toxicity studies. The results of all these evaluations demonstrated that the dual delivery of Mel and TTN could accumulate a safety (without high-dose toxicity) synergistic anti-oxidative effect in oocyte/embryo by passive controlled, and inhibit intra/extracellular ROS levels by an enhanced intracellular penetration.

DNA methylation profile of liver of mice conceived by in vitro fertilization

Offspring generated by in vitro fertilization (IVF) are believed to be healthy but display a possible predisposition to chronic diseases, like hypertension and glucose intolerance. Since epigenetic changes are believed to underlie such phenotype, this study aimed at describing global DNA methylation changes in the liver of adult mice generated by natural mating (FB group) or by IVF. Embryos were generated by IVF or natural mating. At 30 weeks of age, mice were sacrificed. The liver was removed, and global DNA methylation was assessed using whole-genome bisulfite sequencing (WGBS). Genomic Regions for Enrichment Analysis Tool (GREAT) and G:Profilerβ were used to identify differentially methylated regions (DMRs) and for functional enrichment analysis. Overrepresented gene ontology terms were summarized with REVIGO, while canonical pathways (CPs) were identified with Ingenuity® Pathway Analysis. Overall, 2692 DMRs (4.91%) were different between the groups. The majority of DMRs (84.92%) were hypomethylated in the IVF group. Surprisingly, only 0.16% of CpG islands were differentially methylated and only a few DMRs were located on known gene promoters (n = 283) or enhancers (n = 190). Notably, the long-interspersed element (LINE), short-interspersed element (SINE), and long terminal repeat (LTR1) transposable elements showed reduced methylation (P < 0.05) in IVF livers. Cellular metabolic process, hepatic fibrosis, and insulin receptor signaling were some of the principal biological processes and CPs modified by IVF. In summary, IVF modifies the DNA methylation signature in the adult liver, resulting in hypomethylation of genes involved in metabolism and gene transcription regulation. These findings may shed light on the mechanisms underlying the developmental origin of health and disease.

Co-encapsulation of tertinoin and resveratrol by solid lipid nanocarrier (SLN) improves mice in vitro matured oocyte/ morula-compact stage embryo development

As a promising strategy in overcoming drug resistance, the nano drug co-delivery system (NDCDS) can transport two or more drugs into the cell. In this study, we sought to compare the dual and single drug-delivery system, to deliver the optimal dose of Resveratrol (RES) and Tretinoin (TTN) into the in vitro matured oocyte and morula-compact stage embryonic cells. The formation of single (RES/TTN) and dual-drug (RES + TTN)-SLN were confirmed by Uv-vis spectrophotometery, dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) technologies. In two experiments, the oocytes/presumptive zygotes were cultured under various concentrations of the single (RES/TTN) and dual-drug (RES + TTN)-SLN. In vitro toxicity studies, including nuclear staining (Aceto-orcein and Hoechst 33342), H2DCFDA fluorescent staining, chemiluminescence assay, and quantitative reverse transcription-PCR (qRT-PCR) techniques, indicated an excellent oocyte/embryo internalization of RES and TTN. Moreover, when oocytes/embryos were treated with the lowest concentration of RES + TTN-SLN, antioxidants-related genes were upregulated, apoptotic-related genes were downregulated, and intra/extracellular ROS production was reduced. In vitro cytotoxicity studies also demonstrated that single/dual-encapsulation of RES or TTN were safe even at the highest concentration (10 and 5 μM) compared to the control group. To sum it up, both delivery systems of RES and TTN by SLN (dual or single encapsulation) can deliver the optimal dose of RES and TTN into the oocyte/embryo. Where the dual-delivery of RES and TTN even at the lowest concentration (0.25 μM + 0.1 μm) showed a synergistic anti-oxidative effect in oocyte/embryo with a better inhibition of intra/extra-cellular ROS production by an enhanced/controlled intracellular penetration.

The duration of embryo culture after mouse IVF differentially affects cardiovascular and metabolic health in male offspring

STUDY QUESTION

Do the long-term health outcomes following IVF differ depending upon the duration of embryo culture before transfer?

SUMMARY ANSWER

Using a mouse model, we demonstrate that in male but not female offspring, adverse cardiovascular (CV) health was more likely with prolonged culture to the blastocyst stage, but metabolic dysfunction was more likely if embryo transfer (ET) occurred at the early cleavage stage.

WHAT IS KNOWN ALREADY

ART associate with increased risk of adverse CV and metabolic health in offspring, and these findings have been confirmed in animal models in the absence of parental infertility issues. It is unclear which specific ART treatments may cause these risks. There is increasing use of blastocyst, versus cleavage-stage, transfer in clinical ART which does not appear to impair perinatal health of children born, but the longer-term health implications are unknown.

STUDY DESIGN, SIZE, DURATION

Five mouse groups were generated comprising: (i) natural mating (NM)—naturally mated, non-superovulated and undisturbed gestation; (ii) IV-ET-2Cell—in-vivo derived two-cell embryos collected from superovulated mothers, with immediate ET to recipients; (iii) IVF-ET-2Cell—IVF generated embryos, from oocytes from superovulated mothers, cultured to the two-cell stage before ET to recipients; (iv) IV-ET-BL—in-vivo derived blastocysts collected from superovulated mothers, with immediate ET to recipients; (v) IVF-ET-BL—IVF generated embryos, from oocytes from superovulated mothers, cultured to the blastocyst stage before ET to recipients. Both male and female offspring were analysed for growth, CV and metabolic markers of health. There were 8–13 litters generated for each group for analyses; postnatal data were analysed by multilevel random effects regression to take account of between-mother and within-mother variation and litter size.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

C57/BL6 female mice (3–4 weeks old) were used for oocyte production; CBA males for sperm with human tubal fluid medium were used for IVF. Embryos were transferred (ET) to MF1 pseudo-pregnant recipients at the two-cell stage or cultured in synthetic oviductal medium enriched with potassium medium to the blastocyst stage before ET. Control in-vivo embryos from C57BL6 × CBA matings were collected and immediately transferred at the two-cell or blastocyst stage. Postnatal assays included growth rate up to 27 weeks; systolic blood pressure (SBP) at 9, 15 and 21 weeks; lung and serum angiotensin-converting enzyme (ACE) activity at time of cull (27 weeks); glucose tolerance test (GTT; 27 weeks); basal glucose and insulin levels (27 weeks); and lipid accumulation in liver cryosections using Oil Red O imaging (27 weeks).

MAIN RESULTS AND THE ROLE OF CHANCE

Blastocysts formed by IVF developed at a slower rate and comprised fewer cells that in-vivo generated blastocysts without culture (P < 0.05). Postnatal growth rate was increased in all four experimental treatments compared with NM group (P < 0.05). SBP, serum and lung ACE and heart/body weight were higher in IVF-ET-BL versus IVF-ET-2Cell males (P < 0.05) and higher than in other treatment groups, with SBP and lung ACE positively correlated (P < 0.05). Glucose handling (GTT AUC) was poorer and basal insulin levels were higher in IVF-ET-2Cell males than in IVF-ET-BL (P < 0.05) with the glucose:insulin ratio more negatively correlated with body weight in IVF-ET-2Cell males than in other groups. Liver/body weight and liver lipid droplet diameter and density in IVF-ET-2Cell males were higher than in IVF-ET-BL males (P < 0.05). IVF groups had poorer health characteristics than their in-vivo control groups, indicating that outcomes were not caused specifically by background techniques (superovulation, ET). No consistent health effects from duration of culture were identified in female offspring.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Results from experimental animal models cannot be extrapolated to humans. Nevertheless, they are valuable to develop conceptual models, in this case, in the absence of confounding parental infertility, in assessing the safety of ART manipulations.

WIDER IMPLICATIONS OF THE FINDINGS

The study indicates that longer duration of embryo culture after IVF up to blastocyst before ET leads to increased dysfunction of CV health in males compared with IVF and shorter cleavage-stage ET. However, the metabolic health of male offspring was poorer after shorter versus longer culture duration. This distinction indicates that the origin of CV and metabolic health phenotypes after ART may be different. The poorer metabolic health of males after cleavage-stage ET coincides with embryonic genome activation occurring at the time of ET.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported through the European Union FP7-CP-FP Epihealth programme (278418) and FP7-PEOPLE-2012-ITN EpiHealthNet programme (317146) to T.P.F., the Biotechnology and Biological Sciences Research Council (BBSRC) (BB/F007450/1) to T.P.F., and the Saudi government, University of Jeddah and King Abdulaziz University to A.A. The authors have no conflicts of interest to declare.

Comparative analysis of histone H3K4me3 modifications between blastocysts and somatic tissues in cattle

Epigenetic changes induced in the early developmental stages by the surrounding environment can have not only short-term but also long-term consequences throughout life. This concept constitutes the “Developmental Origins of Health and Disease” (DOHaD) hypothesis and encompasses the possibility of controlling livestock health and diseases by epigenetic regulation during early development. As a preliminary step for examining changes of epigenetic modifications in early embryos and their long-lasting effects in fully differentiated somatic tissues, we aimed to obtain high-throughput genome-wide histone H3 lysine 4 trimethylation (H3K4me3) profiles of bovine blastocysts and to compare these data with those from adult somatic tissues in order to extract common and typical features between these tissues in terms of H3K4me3 modifications. Bovine blastocysts were produced in vitro and subjected to chromatin immunoprecipitation-sequencing analysis of H3K4me3. Comparative analysis of the blastocyst-derived H3K4me3 profile with publicly available data from adult liver and muscle tissues revealed that the blastocyst profile could be used as a “sieve” to extract somatic tissue-specific modifications in genes closely related to tissue-specific functions. Furthermore, principal component analysis of the level of common modifications between blastocysts and somatic tissues in meat production-related and imprinted genes well characterized inter- and intra-tissue differences. The results of this study produced a referential genome-wide H3K4me3 profile of bovine blastocysts within the limits of their in vitro source and revealed its common and typical features in relation to the profiles of adult tissues.

Ultrastructure of mitochondria of human oocytes in different clinical conditions during assisted reproduction

Infertility affects around 8% of couples with a slight change in percentage in the last years. Despite the significant efforts made in Assisted Reproductive Technologies (ARTs) in handling this disorder, oocyte quality remains a crucial factor for a positive outcome. A better understanding of the dynamics underlying oocyte maturation, fertilization, and embryo development remains one of the main areas for progress in the ARTs field. Mitochondria are believed to play an essential role in these processes. Mitochondria have a crucial part in producing energy for oocyte maturation and embryo development throughout precise cellular functions comprising Ca²⁺ homeostasis regulation, glycolysis, amino acid and fatty acid metabolism, and regulation of apoptosis. Recent studies suggest that mitochondrial structure, content, and function may be related to oocyte competence, embryo viability, and implantation success during ARTs. Their defects could lead to low fertilization rates and embryonic development failure. This review aimed to provide an overview of the available literature data surrounding the correlation between changes at ultrastructural level of mitochondria or correlated-mitochondrial aggregates and oocyte quality and ARTs treatments. Our reported data demonstrated that oocyte mitochondrial ultrastructural alterations could be partial or complete recovery during the early embryo stages. However, these changes could persist as quiescent during the pre-implantation embryo development, causing abnormalities that become evident only during fetal and postnatal life. These factors led to consider the mitochondria as a crucial marker of oocyte and embryo quality, as well as a strategic target for further prospective therapeutical approaches.

Abnormal Glucose Metabolism in Male Mice Offspring Conceived by in vitro Fertilization and Frozen-Thawed Embryo Transfer

Frozen and thawed embryo transfer (FET) is currently widely applied in routine assisted reproductive technology (ART) procedure. It is of great necessity to assess the safety of FET and investigate the long-term effect including glucose metabolism on FET-conceived offspring. The mouse model is a highly efficient method to figure out the relationship between the process of FET and offspring health. In this study, we obtained mouse offspring of natural conception (NC), in vitro fertilization (IVF), and FET. Glucose and insulin tolerance test (GTT/ITT) were performed on both chow fed or high fat diet (HFD) fed offspring to examine the glucose metabolism status. We detected hepatic PI3K/AKT pathway by western blotting and transcriptome status by RNA-sequencing. Impaired glucose tolerance (IGT) and decreased insulin tolerance were occurred in FET conceived male offspring. After challenged with the HFD-fed, male offspring in FET group performed earlier and severer IGT than IVF group. Furthermore, higher HOMA-IR index and higher serum insulin level post glucose injected in FET-chow group suggested the insulin resistance status. The PI3K/AKT signaling pathway, the major pathway of insulin in the liver, were also disrupted in FET group. Transcriptomics of the liver reveals significantly downregulated in glucose metabolic process and insulin resistance in the FET-chow group. In our study, FET-conceived male mouse offspring presented glucose metabolism dysfunction mainly manifesting insulin resistance. The hepatic insulin signaling pathway were in concordance with reduced glycogen synthesis, increased glycolysis and enhanced gluconeogenesis status in FET-conceived male offspring.

The effects of assisted reproduction technologies on metabolic health and disease†

The increasing prevalence of metabolic diseases places a substantial burden on human health throughout the world. It is believed that predisposition to metabolic disease starts early in life, a period of great susceptibility to epigenetic reprogramming due to environmental insults. Assisted reproductive technologies (ART), i.e., treatments for infertility, may affect embryo development, resulting in multiple adverse health outcomes in postnatal life. The most frequently observed alteration in ART pregnancies is impaired placental nutrient transfer. Moreover, consequent intrauterine growth restriction and low birth weight followed by catch-up growth can all predict future obesity, insulin resistance, and chronic metabolic diseases. In this review, we have focused on evidence of adverse metabolic alterations associated with ART, which can contribute to the development of chronic adult-onset diseases, such as metabolic syndrome, type 2 diabetes, and cardiovascular disease. Due to high phenotypic plasticity, ART pregnancies can produce both offspring with adverse health outcomes, as well as healthy individuals. We further discuss the sex-specific and age-dependent metabolic alterations reflected in ART offspring, and how the degree of interference of a given ART procedure (from mild to more severe manipulation of the egg) affects the occurrence and degree of offspring alterations. Over the last few years, studies have reported signs of cardiometabolic alterations in ART offspring that are detectable at a young age but that do not appear to constitute a high risk of disease and morbidity per se. These abnormal phenotypes could be early indicators of the development of chronic diseases, including metabolic syndrome, in adulthood. The early detection of metabolic alterations could contribute to preventing the onset of disease in adulthood. Such early interventions may counteract the risk factors and improve the long-term health of the individual.

[Metabolic phenotype of adult mice offspring obtained from different variants of embryo transfer]

Assisted reproductive technologies (ART) increasingly occupy the study of human reproduction. In addition, in developed countries they contribute to breeding of more than 50 % of cattle. In the management of collections of genetic lines of laboratory animals, these technologies are obligatory components of cryopreservation and rederivation. ART procedures include the development of early embryos outside the mother's body and the high probability of incomplete synchronization of the physiological state of the surrogate mother and transplanted embryos. Since all this occurs at the stage of the highest susceptibility of embryos to epigenetic reprogramming, the full cycle of ART and its individual components can lead to stable phenotypic changes in the offspring. Their reality is confirmed by studies of the morphological and functional characteristics of sexually mature offspring of CD1 outbred mice, obtained using different variants of early embryo transplantation. Comparative studies of body mass and body composition, basal glucose level and response to glucose load (glucose-tolerance test - GTT) have been done on sexually mature males and females. Animals were separated in 4 groups according to the variant of embryo transplantation: group (control) - natural mating; group (2cl-bl) - incubation of 2-cell up to blastocysts; group (2cl-2cl) - removal and transplantation of the 2-cell embryo without incubation; group (Bl-bl) removal and transplantation of the blastocysts without incubation. All embryos were transplanted to recipient females of the same line. It was found that sexually mature offspring obtained with all variants of transplantations had a higher relative fat content and, correspondingly, lower lean mass compared to the control. This effect was more pronounced in females than in males. Unlike body compositions, embryo transplantations had a greater effect on basal glucose concentration and GTT in males than in females. In this case, the offspring of the 2cl-2cl and 2cl-bl groups were characterized by a higher tolerance to glucose load (GTT) compared with the control and the Bl-bl group. Stable deviations of body compositions and glucose homeostasis indices detected in experimental groups of progenies indicate the phenotypic significance of the embryo transplantations per se.

Effect of culture conditions and method of conception on mouse live birth rate

OBJECTIVE

To understand in a mouse model whether there are differences in the decidua and live birth rate after transfer of blastocysts generated by in vitro fertilization (IVF) or by superovulation with spontaneous mating into unstimulated recipients.

DESIGN

Animal experiment.

SETTING

University-affiliated tertiary hospital.

ANIMAL(S)

Mice.

INTERVENTION(S)

IVF embryos were generated and cultured in either Whitten medium (WM, suboptimal conditions) and 20% O₂ or KSOM medium with amino acids (KAA, optimal conditions) and 5% O₂. The control blastocysts from superovulated mice were flushed out of the uterus 3.5 days (E3.5) after mating (FB group). The resulting blastocysts were transferred to nonsuperovulated CF1 recipients mated to vasectomized males. To understand whether anomalies of decidua were present, the expression of genes involved in decidual development and inflammation was analyzed at E7.5 and E18.5. Similarly, immunostaining was used to evaluate whether the pathways involved in activation of mTORC1 (p-S6) and Cox2 signaling (Cox 2 staining) were altered.

MAIN OUTCOME MEASURE(S)

Live birth rate, gene expression, and immunostaining of decidua.

RESULT(S)

Implantation rates at E7.5 were similar, but in vivo embryos (FB groups) were predicted to result in live births 3.3 times higher (2.2-5.1) and 6.6 times higher (4.7-9.3) compared with optimal and suboptimal cultures, respectively. Expression of genes involved in decidual development and inflammation or localization and intensity of staining for p-S6 (mTOR pathway), or inflammation (Cox 2 pathway) were not different among the groups.

CONCLUSION(S)

The predicted live birth rate was decreased in mouse embryos generated by IVF compared with embryos generated by mating, whereas the implantation rate was not different. Suboptimal culture conditions resulted in lower birth rate. We did not find evidence of abnormalities in decidualization that could explain these findings. These data indicate that blastocysts cultured in stressful conditions are less competent, suggesting that decreasing the number of embryonic manipulations may result in higher live birth rates.

Sex-specific epigenetic profile of inner cell mass of mice conceived in vivo or by IVF

The preimplantation stage of development is exquisitely sensitive to environmental stresses, and changes occurring during this developmental phase may have long-term health effects. Animal studies indicate that IVF offspring display metabolic alterations, including hypertension, glucose intolerance and cardiac hypertrophy, often in a sexual dimorphic fashion. The detailed nature of epigenetic changes following in-vitro culture is, however, unknown. This study was performed to evaluate the epigenetic (using whole-genome bisulfite sequencing (WGBS) and assay for transposase-accessible chromatin using sequencing (ATAC-seq)) and transcriptomic changes (using RNA-seq) occurring in the inner cell mass (ICM) of male or female mouse embryos generated in vivo or by IVF. We found that the ICM of IVF embryos, compared to the in-vivo ICM, differed in 3% of differentially methylated regions (DMRs), of which 0.1% were located on CpG islands. ATAC-seq revealed that 293 regions were more accessible and 101 were less accessible in IVF embryos, while RNA-seq revealed that 21 genes were differentially regulated in IVF embryos. Functional enrichment analysis revealed that stress signalling (STAT and NF-kB signalling), developmental processes and cardiac hypertrophy signalling showed consistent changes in WGBS and ATAC-seq platforms. In contrast, male and female embryos showed minimal changes. Male ICM had an increased number of significantly hyper-methylated DMRs, while only 27 regions showed different chromatin accessibility and only one gene was differentially expressed. In summary, this study provides the first comprehensive analysis of DNA methylation, chromatin accessibility and RNA expression changes induced by IVF in male and female ICMs. This dataset can be of value to all researchers interested in the developmental origin of health and disease (DOHaD) hypothesis and might lead to a better understanding of how early embryonic manipulation may affect adult health.

Transient Changes of Metabolism at the Pronuclear Stage in Mice Influences Skeletal Muscle Phenotype in Adulthood

Skeletal muscle has a remarkable plasticity, and its phenotype is strongly influenced by hormones, transcription factors, and physical activity. However, whether skeletal phenotype can be oriented or not during early embryonic stages has never been investigated. Here, we report that pyruvate as the only source of carbohydrate in the culture medium of mouse one cell stage embryo influenced the establishment of the muscular phenotype in adulthood. We found that pyruvate alone induced changes in the contractile phenotype of the skeletal muscle in a sexually dependent manner. For male mice, a switch to a more glycolytic phenotype was recorded, whereas, in females, the pyruvate induced a switch to a more oxidative phenotype. In addition, the influence of pyruvate on the contractile phenotypes was confirmed in two mouse models of muscle hypertrophy: the well-known myostatin deficient mouse (Mstn-/-) and a mouse carrying a specific deletion of p43, a mitochondrial triiodothyronine receptor. Finally, to understand the link between these adult phenotypes and the early embryonic period, we assessed the levels of two histone H3 post-translational modifications in presence of pyruvate alone just after the wave of chromatin reprogramming specific of the first cell cycle. We showed that H3K4 acetylation level was decreased in Mstn-/- 2-cell embryos, whereas no difference was found for H3K27 trimethylation level, whatever the genotype. These findings demonstrate for the first time that changes in the access of energy substrate during the very first embryonic stage can induce a precocious orientation of skeletal muscle phenotype in adulthood.

Consequences of assisted reproductive technologies for offspring function in cattle

Abnormal fetuses, neonates and adult offspring derived by assisted reproductive technologies (ART) have been reported in humans, rodents and domestic animals. The use of ART has also been associated with an increased likelihood of certain adult diseases. These abnormalities may arise as a result of an excess of or missing maternally derived molecules during invitro culture, because the invitro environment is artificial and suboptimal for embryo development. Nonetheless, the success of ART in overcoming infertility or improving livestock genetics is undeniable. Limitations of invitro embryo production (IVEP) in cattle include lower rates of the establishment and maintenance of pregnancy and an increased incidence of neonatal morbidity and mortality. Moreover, recent studies demonstrated long-term effects of IVEP in cattle, including increased postnatal mortality, altered growth and a slight reduction in the performance of adult dairy cows. This review addresses the effects of an altered preimplantation environment on embryo and fetal programming and offspring development. We discuss cellular and molecular responses of the embryo to the maternal environment, how ART may disturb programming, the possible role of epigenetic effects as a mechanism for altered phenotypes and long-term effects of ART that manifest in postnatal life.

Oxygen concentration alters mitochondrial structure and function in in vitro fertilized preimplantation mouse embryos

STUDY QUESTION

Does the oxygen concentration in the culture medium [either physiologic (5%) or atmospheric (20%)] affect mitochondrial ultrastructure and function in preimplantation mouse embryos generated by IVF?

SUMMARY ANSWER

Embryos cultured in 20% oxygen show increased mitochondrial abnormalities compared to embryos cultured in 5% oxygen.

WHAT IS KNOWN ALREADY

ART are widely used and have resulted in the birth of more than 8 million children. A variety of media and oxygen concentrations are used to culture embryos. Embryos cultured under physiological O2 tension (5%) reach the blastocyst stage faster and have fewer alterations in gene expression when compared with embryos cultured under atmospheric oxygen conditions (20%). The mechanisms by which oxygen tension affects preimplantation development remain unclear, but mitochondria are believed to play an important role. The aim of this study was to evaluate how mitochondrial ultrastructure and function in IVF embryos were affected by culture under physiologic (5%) or atmospheric (20%) oxygen concentrations.

STUDY DESIGN, SIZE, DURATION

Zygotes, 2-cell, 4-cell, morula and blastocyst were flushed out of the uterus after natural fertilization and used as controls. IVF was performed in CF1 x B6D2F1 mice and embryos were cultured in Potassium simplex optimized medium (KSOM) with amino acids (KAA) under 5% and 20% O2 until the blastocyst stage. Embryo development with the addition of antioxidants was also tested.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mitochondrial function was assessed by measuring mitochondrial membrane potential, reactive oxygen species (ROS) production, ATP levels, and the expression of selected genes involved in mitochondrial function. Mitochondria ultrastructure was evaluated by transmission electron microscopy (TEM).

MAIN RESULTS AND THE ROLE OF CHANCE

Embryos cultured under 20% O2 had fewer mitochondria and more vacuoles and hooded (abnormal) mitochondria compared to the other groups (P < 0.05). At the blastocyst stage the mitochondria of IVF embryos cultured in 20% O2 had lower mtDNA copy number, a denser matrix and more lamellar cristae than controls. Overall IVF-generated blastocysts had lower mitochondrial membrane potential, higher ROS levels, together with changes in the expression of selected mitochondrial genes (P < 0.05). ATP levels were significantly lower than controls only under 5% O2, with the 20% O2 IVF group having intermediate levels. Unexpectedly, adding antioxidant to the culture medium did not improve development.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Findings in mice embryos might be different from human embryos.

WIDER IMPLICATIONS OF THE FINDINGS

This study suggests that changes in the mitochondria may be part of the mechanism by which lower oxygen concentration leads to better embryo development and further emphasize the importance of mitochondria as a locus of reprogramming.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by R01 HD 082039 to PFR, the Department of Life, Health and Environmental Sciences, University of L'Aquila, Italy (RIA 2016-2018) and the Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, La Sapienza University of Rome, Italy (University grants 2016-2017). The authors declare no competing interests.

Long-term and transgenerational phenotypic, transcriptional and metabolic effects in rabbit males born following vitrified embryo transfer

The advent of assisted reproductive technologies (ART) in mammals involved an extraordinary change in the environment where the beginning of a new organism takes place. Under in vitro conditions, in which ART is currently being performed, it likely fails to mimic optimal in vivo conditions. This suboptimal environment could mediate in the natural developmental trajectory of the embryo, inducing lasting effects until later life stages that may be inherited by subsequent generations (transgenerational effects). Therefore, we evaluated the potential transgenerational effects of embryo exposure to the cryopreservation-transfer procedure in a rabbit model on the offspring phenotype, molecular physiology of the liver (transcriptome and metabolome) and reproductive performance during three generations (F1, F2 and F3). The results showed that, compared to naturally-conceived animals (NC group), progeny generated after embryo exposure to the cryopreservation-transfer procedure (VT group) exhibited lower body growth, which incurred lower adult body weight in the F1 (direct effects), F2 (intergenerational effects) and F3 (transgenerational effects) generations. Furthermore, VT animals showed intergenerational effects on heart weight and transgenerational effects on liver weight. The RNA-seq data of liver tissue revealed 642 differentially expressed transcripts (DETs) in VT animals from the F1 generation. Of those, 133 were inherited from the F2 and 120 from the F3 generation. Accordingly, 151, 190 and 159 differentially accumulated metabolites (DAMs) were detected from the F1, F2 and F3, respectively. Moreover, targeted metabolomics analysis demonstrated that transgenerational effects were mostly presented in the non-polar fraction. Functional analysis of molecular data suggests weakened zinc and fatty acid metabolism across the generations, associated with alterations in a complex molecular network affecting global hepatic metabolism that could be associated with the phenotype of VT animals. However, these VT animals showed proper reproductive performance, which verified a functional health status. In conclusion, our results establish the long-term transgenerational effects following a vitrified embryo transfer procedure. We showed that the VT phenotype could be the result of the manifestation of embryonic developmental plasticity in response to the stressful conditions during ART procedures.

Long-Term Phenotypic and Proteomic Changes Following Vitrified Embryo Transfer in the Rabbit Model

Nowadays, assisted reproductive technologies (ARTs) are considered valuable contributors to our past, but a future without their use is inconceivable. However, in recent years, several studies have evidenced a potential impact of ART on long-term development in mammal species. To date, the long-term follow-up data are still limited. So far, studies have mainly focused on in vitro fertilization or in vitro culture, with information from gametes/embryos cryopreservation field being practically missing. Herein, we report an approach to determine whether a vitrified embryo transfer procedure would have long-term consequences on the offspring. Using the rabbit as a model, we compared animals derived from vitrified-transferred embryos versus those naturally conceived, studying the growth performance, plus the weight throughout life, and the internal organs/tissues phenotype. The healthy status was assessed over the hematological and biochemical parameters in peripheral blood. Additionally, a comparative proteomic analysis was conducted in the liver tissue to investigate molecular cues related to vitrified embryo transfer in an adult tissue. After vitrified embryo transfer, birth weight was increased, and the growth performance was diminished in a sex-specific manner. In addition, vitrified-transferred animals showed significantly lower body, liver and heart weights in adulthood. Molecular analyses revealed that vitrified embryo transfer triggers reprogramming of the liver proteome. Functional analysis of the differentially expressed proteins showed changes in relation to oxidative phosphorylation and dysregulations in the zinc and lipid metabolism, which has been reported as possible causes of a disturbed growth pattern. Therefore, we conclude that vitrified embryo transfer is not a neutral procedure, and it incurs long-term effects in the offspring both at phenotypic and molecular levels. These results described a striking example of the developmental plasticity exhibited by the mammalian embryo.

PTEN: A Thrifty Gene That Causes Disease in Times of Plenty?

The modern obesity epidemic with associated disorders of metabolism and cancer has been attributed to the presence of "thrifty genes". In the distant past, these genes helped the organism to improve energy efficiency and store excess energy safely as fat to survive periods of famine, but in the present day obesogenic environment, have turned detrimental. I propose PTEN as the likely gene as it has functions that span metabolism, cancer and reproduction, all of which are deranged in obesity and insulin resistance. The activity of PTEN can be calibrated in utero by availability of nutrients by the methylation arm of the epigenetic pathway. Deficiency of protein and choline has been shown to upregulate DNA methyltransferases (DNMT), especially 1 and 3a; these can then methylate promoter region of PTEN and suppress its expression. Thus, the gene is tuned like a metabolic rheostat proportional to the availability of specific nutrients, and the resultant "dose" of the protein, which sits astride and negatively regulates the insulin-PI3K/AKT/mTOR pathway, decides energy usage and proliferation. This "fixes" the metabolic capacity of the organism periconceptionally to a specific postnatal level of nutrition, but when faced with a discordant environment, leads to obesity related diseases.

Pre-Implantation Mouse Embryos Cultured In Vitro under Different Oxygen Concentrations Show Altered Ultrastructures

Assisted Reproductive Technologies routinely utilize different culture media and oxygen (O2) concentrations to culture human embryos. Overall, embryos cultured under physiological O2 tension (5%) have improved development compared to embryos cultured under atmospheric O2 conditions (20%). The mechanisms responsible for this remain unclear. This study aimed to evaluate the effect of physiologic (5%) or atmospheric O2 (20%) tension on the microscopic ultrastructure of pre-implantation mouse embryos using Transmission Electron Microscopy (TEM). Embryos flushed out of the uterus after natural mating were used as the control. For use as the control, 2-cells, 4-cells, morulae, and blastocysts were flushed out of the uterus after natural fertilization. In vitro fertilization (IVF) was performed using potassium simplex optimized medium (KSOM) under different O2 tensions (5% and 20%) until the blastocyst stage. After collection, embryos were subjected to the standard preparative for light microscopy (LM) and TEM. We found that culture in vitro under 5% and 20% O2 results in an increase of vacuolated shaped mitochondria, cytoplasmic vacuolization and presence of multi-vesicular bodies at every embryonic stage. In addition, blastocysts generated by IVF under 5% and 20% O2 showed a lower content of heterochromatin, an interruption of the trophectodermal and inner cell mass cell membranes, an increased density of residual bodies, and high levels of glycogen granules in the cytoplasm. In conclusion, this study suggests that in vitro culture, particularly under atmospheric O2 tension, causes stage-specific changes in preimplantation embryo ultrastructure. In addition, atmospheric (20%) O2 is associated with increased alterations in embryonic ultrastructure; these changes may explain the reduced embryonic development of embryos cultured with 20% O2.

Developmental Plasticity in Response to Embryo Cryopreservation: The Importance of the Vitrification Device in Rabbits

Simple Summary

This study was conducted to demonstrate how embryo manipulation techniques incur phenotypic changes throughout life. This study reports the first evidence demonstrating that the vitrification device used is not a trivial decision, providing valuable information about how the cooling–warming rates during vitrification can be partly responsible of the postnatal phenotypic variations.

Abstract

In this study, we evaluated the effect of embryo vitrification using two different devices on adulthood phenotype in rabbits. In vitro development, prenatal embryo survival, body weight, growth performance, haematological and biochemical peripheral blood analysis, reproductive performance, and lactation performance traits were compared between the experimental groups. They derived from naturally-conceived embryos (NC), fresh-transferred embryos (FT), vitrified-transferred embryos using mini-straw (VTs), or vitrified-transferred embryos using Cryotop (VTc). Straw-vitrified embryos exhibited lower in vitro developmental rates and in vivo survival rates following embryo transfer compared to its Cryotop-vitrified counterparts. Moreover, the VTs group exhibited higher foetal losses than VTc, FT, and NC groups. Independently of the vitrification device, vitrified-transferred (VT) offspring showed a skewed sex ratio in favour of males, and an increased birth bodyweight. In contrast, postnatal daily growth was diminished in all ART (i.e., FT and VT) animals. In adulthood, significant differences in body weight between all groups was founded—all ART progenies weighed less than NC animals and, within ART, VT animals weighed less than FT. For VT groups, weight at adulthood was higher for the VTs group compared with the VTc group. Peripheral blood parameters ranged between common values. Moreover, no differences were found in the fertility rates between experimental groups. Furthermore, similar pregnancy rates, litter sizes, and the number of liveborns were observed, regardless of the experimental group. However, decreased milk yield occurred for VTc and FT animals compared to VTs and NC animals. A similar trend was observed for the milk composition of dry matter and fat. Concordantly, reduced body weight was found for suckling kits in the VTc and FT groups compared to VTs and NC animals. Our findings reveal that developmental changes after the embryo vitrification procedure could be associated with an exhibition of the embryonic developmental plasticity. Moreover, to our best knowledge, this study reports the first evidence demonstrating that the vitrification device used is not a trivial decision, providing valuable information about how the cooling–warming rates during vitrification can be partly responsible of the postnatal phenotypic variations.

Altered expression of DNA damage repair genes in the brain tissue of mice conceived by in vitro fertilization

Our previous study revealed a higher incidence of gene dynamic mutation in newborns conceived by IVF, highlighting that IVF may be disruptive to the DNA stability of IVF offspring. However, the underlying mechanisms remain unclear. The DNA damage repair system plays an essential role in gene dynamic mutation and neurodegenerative disease. To evaluate the long-term impact of IVF on DNA damage repair genes, we established an IVF mouse model and analyzed gene and protein expression levels of MSH2, MSH3, MSH6, MLH1, PMS2, OGG1, APEX1, XPA and RPA1 and also the amount of H2AX phosphorylation of serine 139 which is highly suggestive of DNA double-strand break (γH2AX expression level) in the brain tissue of IVF conceived mice and their DNA methylation status using quantitative real-time PCR, western blotting and pyrosequencing. Furthermore, we assessed the capacity of two specific non-physiological factors in IVF procedures during preimplantation development. The results demonstrated that the expression and methylation levels of some DNA damage repair genes in the brain tissue of IVF mice were significantly changed at 3 weeks, 10 weeks and 1.5 years of age, when compared with the in vivo control group. In support of mouse model findings, oxygen concentration of in vitro culture environment was shown to have the capacity to modulate gene expression and DNA methylation levels of some DNA damage repair genes. In summary, our study indicated that IVF could bring about long-term alterations of gene and protein expression and DNA methylation levels of some DNA damage repair genes in the brain tissue and these alterations might be resulted from the different oxygen concentration of culture environment, providing valuable perspectives to improve the safety and efficiency of IVF at early embryonic stage and also throughout different life stages.

Increased blood pressure and impaired endothelial function after accelerated growth in IVF/ICSI children

STUDY QUESTION

What is the effect of growth velocity (height and weight) in early infancy on metabolic end-points and endothelial function in children born after ART?

SUMMARY ANSWER

Neonatal, infant and childhood growth is positively related to blood pressure in 9-year-old IVF/ICSI offspring, while growth in childhood was negatively associated with endothelial function.

WHAT IS KNOWN ALREADY

Offspring of pregnancies conceived after ART are at risk for later cardiometabolic risk factors. It is well established that early growth is related to numerous later cardiometabolic risk factors such as high blood pressure. This concept is known as the Developmental Origin of Health and Disease theory.

STUDY DESIGN SIZE DURATION

The relation between early growth and later cardiometabolic risk profile was studied in the MEDIUM-KIDS study, a prospective observational cohort study in children born after an IVF/ICSI treatment. In 131 children (48.1% males) at the average age of 9.4 years, cardiometabolic outcomes were assessed and growth data from birth until age 9 years were collected from child welfare centers.

PARTICIPANTS/MATERIALS SETTINGS METHODS

The following cardiometabolic outcomes were assessed: blood pressure, skinfolds, lipid spectrum, hair cortisone and glucose and insulin levels. Data on maximum skin perfusion after transdermal delivery of acetylcholine as a measure of endothelial function were collected.Growth charts were obtained electronically from child welfare centers, which offer free consultations and vaccinations to all Dutch children. At these centers, height and weight are recorded at predefined ages. Growth was defined as z-score difference in weight between two time points. Multivariable linear regression analysis was used to model the relation between growth and cardiometabolic outcomes. The following growth windows were -studied simultaneously in each model: 0-1 month, 1-3 months, 3-6 months, 6-11 months, 11-24 months and 2-6 years. The model was adjusted for height growth in all intervals except for 0-1 month.

MAIN RESULTS AND THE ROLE OF CHANCE

In multivariable linear regression analyses, multiple growth windows were positively associated with blood pressure, for example growth from 2-6 years was significantly related to systolic blood pressure: B = 4.13, P = 0.005. Maximum skin perfusion after acetylcholine was negatively associated with height-adjusted weight gain from 2 to 6 years: B = -0.09 (log scale), P = 0.03. Several growth windows (weight 1-3 months, 3-6 months, 6-11 months, 11-24 months, 2-6 years) were positively linked with total adiposity. Lipids, glucose tolerance indices and cortisone were not related to growth.

LIMITATIONS REASONS FOR CAUTION

This study is of modest size and of observational nature, and we did not include a control group. Therefore, we cannot assess whether the observed associations are causal. It is also not possible to analyze if our observations are specific for, or exacerbated in, the ART population. Ideally, a control group of naturally conceived siblings of IVF/ICSI children should simultaneously be studied to address this limitation and to assess the impact of the ART procedure without the influence of parental (subfertility) characteristics.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this study contribute to our understanding of the reported increased risk for hypertension in ART offspring. We speculate that early, accelerated growth may be involved in the reported increased risk for hypertension in ART offspring, with endothelial dysfunction as a possible underlying mechanism. However, additional research into the mechanisms involved is required.

STUDY FUNDING/COMPETING INTERESTS

The study was financially supported by the March of Dimes, grant number #6-FY13-153. The sponsor of the study had no role in study design, data collection, data analysis, data interpretation or writing of the paper. The authors have no conflict of interest to declare.

TRIAL REGISTRATION NUMBER

NTR4220.

Does in vitro fertilization affect the expression of miRNAs and their biogenesis pathway in preimplantation mouse embryos?

BACKGROUND

In vitro fertilization (IVF) is a well-accepted procedure which has been utilized for the treatment of infertile patients. As embryos at early stages of development are very vulnerable, the IVF conditions may influence genetic and epigenetic regulation of preimplantation mouse embryo.

METHODS

We assessed the effect of IVF on the expression of developmental and implantation related miRNAs (miR-21, miR-93, miR-24, and let-7a), their common presumptive target (Stat3), and miRNA biogenesis pathway genes (Drosha, Dgcr8, Exportin-5, Dicer, and Ago2). in vivo 8-cell and blastocysts were compared to IVF embryos. Expression levels of miRNAs, Stat3, and miRNA biogenesis pathway genes were evaluated by qRT-PCR in in vivo (n = 8) and IVF (n = 4) embryos.

RESULTS

The expression levels of let-7a and Stat3 were significantly reduced in IVF blastocyst when compared with in vivo (p = .004 and p = .009, respectively). Nevertheless, the IVF procedure did not influence the expression levels of miRNA biogenesis pathway components in 8-cell and blastocyst embryos.

CONCLUSIONS

Downregulation of let-7a and developmental related transcription factor, Stat3, in IVF mouse blastocysts may affect preimplantation development and implantation of embryos. Moreover, the genes of the miRNA biogenesis pathway were not changed in preimplantation mouse embryos through the IVF procedure.

Increased susceptibility of mice obtained from in vitro fertilization to global cerebral ischemia-reperfusion injury: possible role of hydrogen sulphide and its biosynthetic enzymes

Aim of the Study: This study was designed to explore the relative susceptibility of in vitro fertilization (IVF)-conceived mice to global cerebral ischemic injury with the possible role of hydrogen sulphide and enzymes responsible for its production.Materials and Methods: IVF was carried to obtain pups, which were allowed to grow to the age of eight weeks. Thereafter, male mice were subjected to 20 min of global ischemia and 24 h of reperfusion. The mice obtained from other groups including normal mating, superovulation but normal mating and normal mating but embryo implantation were also subjected to global ischemia-reperfusion (I/R) injury.Results: IVF-derived mice exhibited significant more injury in response to I/R injury in comparison to other groups assessed in terms of impairment in locomotor activity, development of motor in coordination, neurological severity score, cerebral infarction and apoptosis markers (caspase-3 activity and Bcl-2 expression). Moreover, there was a relative decrease in the brain levels of hydrogen sulphide (H₂S) and its biosynthetic enzymes viz. cystathionine-β-synthase and cystathionine-γ-lyase. Interestingly, the levels of H₂S and cystathionine-γ-lyase were significantly low in IVF-derived mice in basal conditions also, i.e. before subjecting to I/R injury and these biochemical alterations were associated with the behavioural deficits in mice, even before subjecting to I/R injury.Conclusion: It is concluded that in vitro fertilization-derived mice are more susceptible to global cerebral I/R injury, which may be possibly due to decreased levels of hydrogen sulphide and its biosynthetic enzymes viz., cystathionine-β-synthase and cystathionine-γ-lyase.

Melatonin regulates the activities of ovary and delays the fertility decline in female animals via MT1/AMPK pathway

Female fertility irreversibly declines with aging, and this is primarily associated with the decreased quality and quantity of oocytes. To evaluate whether a long-term of melatonin treatment would improve the fertility of aged mice, different concentrations of melatonin (10^-3 , 10^-5 , 10^-7  mol/L) were supplemented into drinking water. Melatonin treatments improved the litter sizes of mice at the age of 24 weeks. Mice treated with 10^-5  mol/L melatonin had the largest litter size among other concentrations. At this optimal concentration, melatonin not only significantly increased the total number of oocytes but also their quality, having more oocytes with normal morphology that could generate more blastocyst after in vitro fertilization in melatonin (10^-5  mol/L)-treated group than that in the controls. When these blastocysts were transferred to recipients, the litter size was also significantly larger in melatonin treated mice than that in controls. The increases in TAOC and SOD level and decreases in MDA were detected in ovaries and uterus from melatonin-treated mice compared to the controls. Melatonin reduced ROS level and maintained mitochondrial membrane potential in the oocytes cultured in vitro. Mechanistically studies revealed that the beneficial effects of melatonin on oocytes were mediated by MT1 receptor and AMPK pathway. Thereafter, MT1 knocking out (MT1-KO) were generated and shown significantly reduced number of oocytes and litter size. The expression of SIRT1, C-myc, and CHOP were downregulated in the ovary of MT1-KO mice, but SIRT1 and p-NF-kB protein level were elevated in response to disturbed redox balance. The results have convincingly proven that melatonin administration delays ovary aging and improves fertility in mice via MT1/AMPK pathway.

Revisiting the early days of oocyte and embryo donation: relevance to contemporary clinical practice

Oocyte and embryo donation have evolved significantly since they were first introduced to treat human infertility nearly four decades ago. Social, ethical, and regulatory challenges to oocyte and embryo donation have generated controversy and invited public scrutiny. However, oocyte and embryo donation continued to provide physicians the opportunity to treat the "untreatable." Undoubtedly, clinical practices related to oocyte and embryo donation have greatly changed over the years. Yet, they have endured as viable choices of treatment for many patients and their physicians, remained popular owing to their versatility, and, perhaps most importantly, provided consistently high pregnancy success rates.