N-Acetylcysteine, a glutathione precursor, reverts vascular dysfunction and endothelial epigenetic programming in intrauterine growth restricted guinea pigs

Epigenetic regulation by hypoxia, N-acetylcysteine and hydrogen sulphide of the fetal vasculature in growth restricted offspring: A study in humans and chicken embryos

Fetal growth restriction (FGR) is a common outcome in human suboptimal gestation and is related to prenatal origins of cardiovascular dysfunction in offspring. Despite this, therapy of human translational potential has not been identified. Using human umbilical and placental vessels and the chicken embryo model, we combined cellular, molecular, and functional studies to determine whether N-acetylcysteine (NAC) and hydrogen sulphide (H2S) protect cardiovascular function in growth-restricted unborn offspring. In human umbilical and placental arteries from control or FGR pregnancy and in vessels from near-term chicken embryos incubated under normoxic or hypoxic conditions, we determined the expression of the H2S gene CTH (i.e. cystathionine γ-lyase) (via quantitative PCR), the production of H2S (enzymatic activity), the DNA methylation profile (pyrosequencing) and vasodilator reactivity (wire myography) in the presence and absence of NAC treatment. The data show that FGR and hypoxia increased CTH expression in the embryonic/fetal vasculature in both species. NAC treatment increased aortic CTH expression and H2S production and enhanced third-order femoral artery dilator responses to the H2S donor sodium hydrosulphide in chicken embryos. NAC treatment also restored impaired endothelial relaxation in human third-to-fourth order chorionic arteries from FGR pregnancies and in third-order femoral arteries from hypoxic chicken embryos. This NAC-induced protection against endothelial dysfunction in hypoxic chicken embryos was mediated via nitric oxide independent mechanisms. Both developmental hypoxia and NAC promoted vascular changes in CTH DNA and NOS3 methylation patterns in chicken embryos. Combined, therefore, the data support that the effects of NAC and H2S offer a powerful mechanism of human translational potential against fetal cardiovascular dysfunction in complicated pregnancy. KEY POINTS: Gestation complicated by chronic fetal hypoxia and fetal growth restriction (FGR) increases a prenatal origin of cardiovascular disease in offspring, increasing interest in antenatal therapy to prevent against a fetal origin of cardiovascular dysfunction. We investigated the effects between N-acetylcysteine (NAC) and hydrogen sulphide (H2S) in the vasculature in FGR human pregnancy and in chronically hypoxic chicken embryos. Combining cellular, molecular, epigenetic and functional studies, we show that the vascular expression and synthesis of H2S is enhanced in hypoxic and FGR unborn offspring in both species and this acts to protect their vasculature. Therefore, the NAC/H2S pathway offers a powerful therapeutic mechanism of human translational potential against fetal cardiovascular dysfunction in complicated pregnancy.

Guidelines for assessing maternal cardiovascular physiology during pregnancy and postpartum

Maternal mortality rates are at an all-time high across the world and are set to increase in subsequent years. Cardiovascular disease is the leading cause of death during pregnancy and postpartum, especially in the United States. Therefore, understanding the physiological changes in the cardiovascular system during normal pregnancy is necessary to understand disease-related pathology. Significant systemic and cardiovascular physiological changes occur during pregnancy that are essential for supporting the maternal-fetal dyad. The physiological impact of pregnancy on the cardiovascular system has been examined in both experimental animal models and in humans. However, there is a continued need in this field of study to provide increased rigor and reproducibility. Therefore, these guidelines aim to provide information regarding best practices and recommendations to accurately and rigorously measure cardiovascular physiology during normal and cardiovascular disease-complicated pregnancies in human and animal models.

Nurturing through Nutrition: Exploring the Role of Antioxidants in Maternal Diet during Pregnancy to Mitigate Developmental Programming of Chronic Diseases

Chronic diseases represent one of the major causes of death worldwide. It has been suggested that pregnancy-related conditions, such as gestational diabetes mellitus (GDM), maternal obesity (MO), and intra-uterine growth restriction (IUGR) induce an adverse intrauterine environment, increasing the offspring's predisposition to chronic diseases later in life. Research has suggested that mitochondrial function and oxidative stress may play a role in the developmental programming of chronic diseases. Having this in mind, in this review, we include evidence that mitochondrial dysfunction and oxidative stress are mechanisms by which GDM, MO, and IUGR program the offspring to chronic diseases. In this specific context, we explore the promising advantages of maternal antioxidant supplementation using compounds such as resveratrol, curcumin, N-acetylcysteine (NAC), and Mitoquinone (MitoQ) in addressing the metabolic dysfunction and oxidative stress associated with GDM, MO, and IUGR in fetoplacental and offspring metabolic health. This approach holds potential to mitigate developmental programming-related risk of chronic diseases, serving as a probable intervention for disease prevention.

Ovarian tissue cryopreservation and transplantation: a review on reactive oxygen species generation and antioxidant therapy

Cancer is the leading cause of death worldwide. Fortunately, the survival rate of cancer continues to rise, owing to advances in cancer treatments. However, these treatments are gonadotoxic and cause infertility. Ovarian tissue cryopreservation and transplantation (OTCT) is the most flexible option to preserve fertility in women and children with cancer. However, OTCT is associated with significant follicle loss and an accompanying short lifespan of the grafts. There has been a decade of research in cryopreservation-induced oxidative stress in single cells with significant successes in mitigating this major source of loss of viability. However, despite its success elsewhere and beyond a few promising experiments, little attention has been paid to this key aspect of OTCT-induced damage. As more and more clinical practices adopt OTCT for fertility preservation, it is a critical time to review oxidative stress as a cause of damage and to outline potential ameliorative interventions. Here we give an overview of the application of OTCT for female fertility preservation and existing challenges; clarify the potential contribution of oxidative stress in ovarian follicle loss; and highlight potential ability of antioxidant treatments to mitigate the OTCT-induced injuries that might be of interest to cryobiologists and reproductive clinicians.

Chorionicity-associated variation in metabolic phenotype of cord blood in twin

BACKGROUND

Monochorionic (MC) twins present a higher incidence of unfavorable clinical perinatal outcomes than dichorionic (DC) twins, often in association with placental vascular anastomosis. In this study, we profiled the umbilical cord plasma metabolomes of uncomplicated MC and DC twin pregnancies and related these to several offspring outcomes, previously associated with birthweight.

METHODS

Umbilical vein blood samples were collected at birth from 25 pairs of uncomplicated MC twins and 24 pairs of uncomplicated DC twins. The samples were subjected to gas chromatography-mass spectrometry-based metabolomics. 152 metabolites were identified from the cord plasma samples of MC and DC twins. Partial least squares discriminant analysis and pathway analysis were performed to compare within DC/MC twin pairs and between DC and MC twins. A generalized estimating equation (GEE) model was utilized to explore the correlation between metabolic differences and birthweight discordance within and between twin pairs.

RESULTS

Our study revealed clear differences between the metabolite profiles of umbilical cord plasma of MC and DC twins. Metabolite profiles in MC within twin pairs and DC within twin pairs were characterized by the differences in 2 - hydroxyglutaramic acid levels and nicotinamide levels, respectively. The metabolic pathways of GSH, tryptophan, and fatty acid metabolism, were significantly downregulated in MC twins compared to DC twins. In addition, the concentration of caffeine and decamethyl-cyclopentasiloxane (D5) was positively correlated with birthweight in MC and DC twins.

CONCLUSION

This study demonstrated that the altered metabolites in umbilical plasma made contributions to the different chorionicities between uncomplicated MC twins and DC twins. The chorionicity of twins seems to affect the metabolic cross-talk between co-twin pairs and be related to birthweight discordance of twins.

Prenatal interventions for fetal growth restriction in animal models: A systematic review

Fetal growth restriction (FGR) in human pregnancy is associated with perinatal mortality, short- and long-term morbidities. No prenatal therapy is currently established despite decades of research. We aimed to review interventions in animal models for prenatal FGR treatment, and to seek the next steps for an effective clinical therapy. We registered our protocol and searched MEDLINE, Embase, and The Cochrane Library with no language restrictions, in accordance with the PRISMA guideline. We included all studies that reported the effects of any prenatal intervention in animal models of induced FGR. From 3257 screened studies, 202 describing 237 interventions were included for the final synthesis. Mice and rats were the most used animals (79%) followed by sheep (16%). Antioxidants (23%), followed by vasodilators (18%), nutrients (14%), and immunomodulators (12%) were the most tested therapy. Two-thirds of studies only reported delivery or immediate neonatal outcomes. Adverse effects were rarely reported (11%). Most studies (73%), independent of the intervention, showed a benefit in fetal survival or birthweight. The risk of bias was high, mostly due to the lack of randomization, allocation concealment, and blinding. Future research should aim to describe both short- and long-term outcomes across various organ systems in well-characterized models. Further efforts must be made to reduce selection, performance, and detection bias.

Maternal supply of cysteamine alleviates oxidative stress and enhances angiogenesis in porcine placenta

BACKGROUND

Oxidative stress in placenta is associated with the occurrence of adverse pregnancy outcomes in sow, but there are few satisfactory treatment strategies for these conditions. This study investigated the potential of cysteamine (CS) as an antioxidant protectant for regulating the reproductive performance, redox status, and placental angiogenesis of sows.

METHODS

The placental oxidative stress status and vascular density of piglets with different birth weights: < 1.0 kg (low birth weight, LBW) and 1.4-1.6 kg (normal birth weight, NBW) were evaluated, followed by allotting 84 sows to four treatments (n = 21) and feeding them with a basal diet supplemented with 0, 100, 300, or 500 mg/kg of CS from d 85 of gestation to d 21 of lactation, respectively. Placenta, serum, and colostrum samples of sows or piglets were collected, and the characteristics of sows and piglets were recorded. Furthermore, the in vivo results were validated using porcine vascular endothelial cells (PVECs).

RESULTS

Compared with the NBW placentae, the LBW placentae showed increased oxidative damage and were vulnerable to angiogenesis impairment. Particularly, H2O2-induced oxidative stress prompted intracellular reactive oxygen species generation and inhibited the tube formation and migration of PVECs as well as the expression of vascular endothelial growth factor-A (VEGF-A) in vitro. However, dietary CS supplementation can alleviate oxidative stress and improve the reproductive performance of sows. Specifically, compared with the control group, dietary 100 mg/kg CS could (1) decrease the stillbirth and invalid rates, and increase both the piglet birth weight in the low yield sows and the placental efficiency; (2) increase glutathione and reduce malondialdehyde in both the serum and the colostrum of sows; (3) increase the levels of total antioxidant capacity and glutathione in LBW placentae; (4) increase the vascular density, the mRNA level of VEGF-A, and the immune-staining intensity of platelet endothelial cell adhesion molecule-1 in the LBW placentae. Furthermore, the in vitro experiment indicated that CS pre-treatment could significantly reverse the NADPH oxidase 2-ROS-mediated inactivation of signal transducer and activator of transcription-3 (Stat3) signaling pathway induced by H2O2 inhibition of the proliferation, tube formation, and migration of PVECs. Meanwhile, inhibition of Stat3 significantly decreased the cell viability, tube formation and the VEGF-A protein level in CS pretreated with H2O2-cultured PVECs.

CONCLUSIONS

The results indicated that oxidative stress and impaired angiogenesis might contribute to the occurrence of LBW piglets during pregnancy, but CS supplementation at 100 mg/kg during late gestation and lactation of sows could alleviate oxidative stress and enhance angiogenesis in placenta, thereby increasing birth weight in low yield sows and reducing stillbirth rate. The in vitro data showed that the underlying mechanism for the positive effects of CS might be related to the activation of Stat3 in PVECs.

Mechanisms of Impaired Lung Development and Ciliation in Mannosidase-1-Alpha-2 (Man1a2) Mutants

BACKGROUND

Ciliary defects cause heterogenous phenotypes related to mutation burden which lead to impaired development. A previously reported homozygous deletion in the Man1a2 gene causes lethal respiratory failure in newborn pups and decreased lung ciliation compared with wild type (WT) pups. The effects of heterozygous mutation, and the potential for rescue are not known.

PURPOSE

We hypothesized that survival and lung ciliation, (a) would decrease progressively in Man1a2 +/- heterozygous and Man1a2 -/- null newborn pups compared with WT, and (b) could be enhanced by gestational treatment with N-Acetyl-cysteine (NAC), an antioxidant.

METHODS

Man1a2+/- adult mice were fed NAC or placebo from a week before breeding through gestation. Survival of newborn pups was monitored for 24 h. Lungs, liver and tails were harvested for morphology, genotyping, and transcriptional profiling.

RESULTS

Survival (p = 0.0001, Kaplan-Meier) and percent lung ciliation (p = 0.0001, ANOVA) measured by frequency of Arl13b+ respiratory epithelial cells decreased progressively, as hypothesized. Compared with placebo, gestational NAC treatment enhanced (a) lung ciliation in pups with each genotype, (b) survival in heterozygous pups (p = 0.017) but not in WT or null pups. Whole transcriptome of lung but not liver demonstrated patterns of up- and down-regulated genes that were identical in living heterozygous and WT pups, and completely opposite to those in dead heterozygous and null pups. Systems biology analysis enabled reconstruction of protein interaction networks that yielded functionally relevant modules and their interactions. In these networks, the mutant Man1a2 enzyme contributes to abnormal synthesis of proteins essential for lung development. The associated unfolded protein, hypoxic and oxidative stress responses can be mitigated with NAC. Comparisons with the developing human fetal lung transcriptome show that NAC likely restores normal vascular and epithelial tube morphogenesis in Man1a2 mutant mice.

CONCLUSION

Survival and lung ciliation in the Man1a2 mutant mouse, and its improvement with N-Acetyl cysteine is genotype-dependent. NAC-mediated rescue depends on the central role for oxidative and hypoxic stress in regulating ciliary function and organogenesis during development.

Novel insights for the role of nitric oxide in placental vascular function during and beyond pregnancy

More than 30 years have passed since endothelial nitric oxide synthesis was described using the umbilical artery and vein endothelium. That seminal report set the cornerstone for unveiling the molecular aspects of endothelial function. In parallel, the understanding of placental physiology has gained growing interest, due to its crucial role in intrauterine development, with considerable long-term health consequences. This review discusses the evidence for nitric oxide (NO) as a critical player of placental development and function, with a special focus on endothelial nitric oxide synthase (eNOS) vascular effects. Also, the regulation of eNOS-dependent vascular responses in normal pregnancy and pregnancy-related diseases and their impact on prenatal and postnatal vascular health are discussed. Recent and compelling evidence has reinforced that eNOS regulation results from a complex network of processes, with novel data concerning mechanisms such as mechano-sensing, epigenetic, posttranslational modifications, and the expression of NO- and l-arginine-related pathways. In this regard, most of these mechanisms are expressed in an arterial-venous-specific manner and reflect traits of the fetal systemic circulation. Several studies using umbilical endothelial cells are not aimed to understand placental function but general endothelial function, reinforcing the influence of the placenta on general knowledge in physiology.

Mitochondria antioxidant protection against cardiovascular dysfunction programmed by early-onset gestational hypoxia

Mitochondria-derived oxidative stress during fetal development increases cardiovascular risk in adult offspring of pregnancies complicated by chronic fetal hypoxia. We investigated the efficacy of the mitochondria-targeted antioxidant MitoQ in preventing cardiovascular dysfunction in adult rat offspring exposed to gestational hypoxia, integrating functional experiments in vivo, with those at the isolated organ and molecular levels. Rats were randomized to normoxic or hypoxic (13%-14% O₂ ) pregnancy ± MitoQ (500 μM day^-1 ) in the maternal drinking water. At 4 months of age, one cohort of male offspring was chronically instrumented with vascular catheters and flow probes to test in vivo cardiovascular function. In a second cohort, the heart was isolated and mounted onto a Langendorff preparation. To establish mechanisms linking gestational hypoxia with cardiovascular dysfunction and protection by MitoQ, we quantified the expression of antioxidant system, β-adrenergic signaling, and calcium handling genes in the fetus and adult, in frozen tissues from a third cohort. Maternal MitoQ in hypoxic pregnancy protected offspring against increased α₁ -adrenergic reactivity of the cardiovascular system, enhanced reactive hyperemia in peripheral vascular beds, and sympathetic dominance, hypercontractility and diastolic dysfunction in the heart. Inhibition of Nfe2l2-mediated oxidative stress in the fetal heart and preservation of calcium regulatory responses in the hearts of fetal and adult offspring link molecular mechanisms to the protective actions of MitoQ treatment of hypoxic pregnancy. Therefore, these data show the efficacy of MitoQ in buffering mitochondrial stress through NADPH-induced oxidative damage and the prevention of programmed cardiovascular disease in adult offspring of hypoxic pregnancy.

Integrated Analysis of Key Genes and Pathways Involved in Fetal Growth Restriction and Their Associations With the Dysregulation of the Maternal Immune System

Fetal growth restriction (FGR) is a common pregnancy complication and a risk factor for infant death. Most patients with FGR have preeclampsia, gestational diabetes mellitus, or other etiologies, making it difficult to determine the specific molecular mechanisms underlying FGR. In this study, an integrated analysis was performed using gene expression profiles obtained from Gene Expression Omnibus. Differentially expressed genes (DEGs) between healthy and FGR groups were screened and evaluated by functional enrichment and network analyses. In total, 80 common DEGs (FDR < 0.05) and 17 significant DEGs (FDR < 0.005) were screened. These genes were enriched for functions in immune system dysregulation in the placenta based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses. Among hub genes identified as candidates for FGR and fetal reprogramming, LEP, GBP5, HLA–DQA1, and CTGF were checked by quantitative polymerase chain reaction, immunohistochemistry, and western blot assays in placental tissues. Immune imbalance could cause hypoxia environment in placenta tissues, thus regulating the fetal-reprogramming. A significant association between CTGF and HIF-1α levels was confirmed in placenta tissues and HTR8 cells under hypoxia. Our results suggest that an immune imbalance in the placenta causes FGR without other complications. We provide the first evidence for roles of CTGF in FGR and show that CTGF may function via HIF-1α-related pathways. Our findings elucidate the pathogenesis of FGR and provide new therapeutic targets.

Adaptations of the human placenta to hypoxia: opportunities for interventions in fetal growth restriction

BACKGROUND

The placenta is the functional interface between the mother and the fetus during pregnancy, and a critical determinant of fetal growth and life-long health. In the first trimester, it develops under a low-oxygen environment, which is essential for the conceptus who has little defense against reactive oxygen species produced during oxidative metabolism. However, failure of invasive trophoblasts to sufficiently remodel uterine arteries toward dilated vessels by the end of the first trimester can lead to reduced/intermittent blood flow, persistent hypoxia and oxidative stress in the placenta with consequences for fetal growth. Fetal growth restriction (FGR) is observed in ∼10% of pregnancies and is frequently seen in association with other pregnancy complications, such as preeclampsia (PE). FGR is one of the main challenges for obstetricians and pediatricians, as smaller fetuses have greater perinatal risks of morbidity and mortality and postnatal risks of neurodevelopmental and cardio-metabolic disorders.

OBJECTIVE AND RATIONALE

The aim of this review was to examine the importance of placental responses to changing oxygen environments during abnormal pregnancy in terms of cellular, molecular and functional changes in order to highlight new therapeutic pathways, and to pinpoint approaches aimed at enhancing oxygen supply and/or mitigating oxidative stress in the placenta as a mean of optimizing fetal growth.

SEARCH METHODS

An extensive online search of peer-reviewed articles using PubMed was performed with combinations of search terms including pregnancy, placenta, trophoblast, oxygen, hypoxia, high altitude, FGR and PE (last updated in May 2020).

OUTCOMES

Trophoblast differentiation and placental establishment are governed by oxygen availability/hypoxia in early pregnancy. The placental response to late gestational hypoxia includes changes in syncytialization, mitochondrial functions, endoplasmic reticulum stress, hormone production, nutrient handling and angiogenic factor secretion. The nature of these changes depends on the extent of hypoxia, with some responses appearing adaptive and others appearing detrimental to the placental support of fetal growth. Emerging approaches that aim to increase placental oxygen supply and/or reduce the impacts of excessive oxidative stress are promising for their potential to prevent/treat FGR.

WIDER IMPLICATIONS

There are many risks and challenges of intervening during pregnancy that must be considered. The establishment of human trophoblast stem cell lines and organoids will allow further mechanistic studies of the effects of hypoxia and may lead to advanced screening of drugs for use in pregnancies complicated by placental insufficiency/hypoxia. Since no treatments are currently available, a better understanding of placental adaptations to hypoxia would help to develop therapies or repurpose drugs to optimize placental function and fetal growth, with life-long benefits to human health.

MiR-21-5p directly contributes to regulating eNOS expression in human artery endothelial cells under normoxia and hypoxia

Clinical conditions associated with hypoxia and oxidative stress, such as fetal growth restriction (FGR), results in endothelial dysfunction. Previous reports show that changes in eNOS expression under these conditions are tightly controlled by DNA methylation and histone posttranslational modifications. However, the contribution of an orchestrating epigenetic mechanism, such as miRNAs, on the NO-related genes expression has not been addressed. We aimed to determine the levels of miRNAs highly expressed in normal endothelial cells (EC), miR-21 and miR-126, in FGR human umbilical artery EC (HUAEC), and their effects on hypoxia-dependent regulation of both, NO-related and oxidative stress-related genes. Results were validated by transcriptome analysis of HUAEC cultured under chronic low oxygen conditions. Cultured FGR-HUAEC showed decreased hsa-miR-21, DDAH1, SOD1, and NRF2, but increased miR-126, NOX4, and eNOS levels, compared with controls. MiR-21-5p levels in FGR were associated with increased hg-miR-21 gene promoter methylation, with no changes in hg-miR-126 gene promoter methylation. HUAEC exposed to hypoxia showed a transient increase in eNOS and DDAH11, paralleled by decrease miR-21-5p levels, but no changes in miR-126-3p and the other genes under study. Transcriptome profiling showed an inverse relationship among miR-21 and several transcripts targeted by miR-21 in HUAEC exposed to hypoxia, meanwhile miR-21-5p-mimic decreased eNOS and DDAH1 transcripts stability, blocking their induction by hypoxia. Consequently, FGR programs a hypoxia-related miRNA that contributes to the regulation of the NO pathway, involving a direct effect of miR-21-5p on eNOS transcript stability, not previously reported. Moreover, hypoxia downregulates miR-21-5p, contributing to increasing the expression of NO-related genes in arterial endothelial cells.

Association of Plasma Total Cysteine and Anthropometric Status in 6-30 Months Old Indian Children

High-quality protein has been associated with child growth; however, the role of the amino acid cysteine remains unclear. The aim was to measure the extent to which plasma total cysteine (tCys) concentration is associated with anthropometric status in children aged 6–30 months living in New Delhi, India. The study was a prospective cohort study including 2102 children. We calculated Z-scores for height-for-age (HAZ), weight-for-height (WHZ), or weight-for-age (WAZ) according to the WHO Child Growth Standards. We used multiple regression models to estimate the association between tCys and the anthropometric indices. A high proportion of the children were categorized as malnourished at enrolment; 41% were stunted (HAZ ≤ −2), 19% were wasted (WHZ ≤ −2) and 42% underweight (WAZ ≤ −2). Plasma total cysteine (tCys) was significantly associated with HAZ, WHZ and WAZ after adjusting for relevant confounders (p < 0.001). Low tCys (≤25th percentile) was associated with a decrease of 0.28 Z-scores for HAZ, 0.10 Z-scores for WHZ, and 0.21 Z-scores for WAZ compared to being >25th percentile. In young Indian children from low-to-middle socioeconomic neighborhoods, a low plasma total cysteine concentration was associated with an increased risk of poor anthropometric status.

Association of Maternal Plasma Total Cysteine and Growth among Infants in Nepal: A Cohort Study

Cysteine is a semi-essential amino acid that has been positively associated with growth in children. However, transgenerational effects remain unclear. The aim of this analysis was to assess whether maternal plasma total cysteine (tCys) concentration is associated with various growth indicators in infants living in peri-urban settings in Bhaktapur, Nepal. We used data from the 561 mothers enrolled in an ongoing randomized controlled trial. We built linear regression models to evaluate the associations between maternal tCys and birth weight, length-for-age Z-scores (LAZ) and weight-for-length Z-scores (WLZ) at birth and six months of age. Maternal tCys was inversely associated with birth weight among boys after adjusting for confounders (p < 0.05). In addition, there was a negative association between maternal tCys and LAZ at birth (p < 0.01). No associations between maternal tCys and the other anthropometric indicators were found significant, although there was a tendency for maternal tCys to be associated positively with WLZ at birth among girls (p < 0.10). This is a first study evaluating transgenerational relation of tCys on growth in infants. Further, larger and more comprehensive studies are needed to determine if and how maternal tCys alters child growth.

Revisiting pharmacology of oxidative stress and endothelial dysfunction in cardiovascular disease: Evidence for redox-based therapies

According to the latest Global Burden of Disease Study data, non-communicable diseases in general and cardiovascular disease (CVD) in particular are the leading cause of premature death and reduced quality of life. Demographic shifts, unhealthy lifestyles and a higher burden of adverse environmental factors provide an explanation for these findings. The expected growing prevalence of CVD requires enhanced research efforts for identification and characterisation of novel therapeutic targets and strategies. Cardiovascular risk factors including classical (e.g. hypertension, diabetes, hypercholesterolaemia) and non-classical (e.g. environmental stress) factors induce the development of endothelial dysfunction, which is closely associated with oxidant stress and vascular inflammation and results in CVD, particularly in older adults. Most classically successful therapies for CVD display vasoprotective, antioxidant and anti-inflammatory effects, but were originally designed with other therapeutic aims. So far, only a few 'redox drugs' are in clinical use and many antioxidant strategies have not met expectations. With the present review, we summarise the actual knowledge on CVD pathomechanisms, with special emphasis on endothelial dysfunction, adverse redox signalling and oxidative stress, highlighting the preclinical and clinical evidence. In addition, we provide a brief overview of established CVD therapies and their relation to endothelial dysfunction and oxidative stress. Finally, we discuss novel strategies for redox-based CVD therapies trying to explain why, despite a clear link between endothelial dysfunction and adverse redox signalling and oxidative stress, redox- and oxidative stress-based therapies have not yet provided a breakthrough in the treatment of endothelial dysfunction and CVD.

Prenatal Amino Acid Supplementation to Improve Fetal Growth: A Systematic Review and Meta-Analysis

Aberrant fetal growth remains a leading cause of perinatal morbidity and mortality and is associated with a risk of developing non-communicable diseases later in life. We performed a systematic review and meta-analysis combining human and animal studies to assess whether prenatal amino acid (AA) supplementation could be a promising approach to promote healthy fetal growth. PubMed, Embase, and Cochrane libraries were searched to identify studies orally supplementing the following AA groups during gestation: (1) arginine family, (2) branched chain (BCAA), and (3) methyl donors. The primary outcome was fetal/birth weight. Twenty-two human and 89 animal studies were included in the systematic review. The arginine family and, especially, arginine itself were studied the most. Our meta-analysis showed beneficial effects of arginine and (N-Carbamyl) glutamate (NCG) but not aspartic acid and citrulline on fetal/birth weight. However, no effects were reported when an isonitrogenous control diet was included. BCAA and methyl donor supplementation did not affect fetal/birth weight. Arginine family supplementation, in particular arginine and NCG, improves fetal growth in complicated pregnancies. BCAA and methyl donor supplementation do not seem to be as promising in targeting fetal growth. Well-controlled research in complicated pregnancies is needed before ruling out AA supplements or preferring arginine above other AAs.

Effects of N-Acetylcysteine on the reproductive performance, oxidative stress and RNA sequencing of Nubian goats

N-acetylcysteine (NAC) has been found to enhance the protective ability of cells to counter balance oxidative stress and inflammation. To investigate the effects of dietary NAC supplementation on the reproductive performance of goats, the reproductive performance and endometrial transcriptome of goats fed with diets with NAC (NAC group) and without NAC supplementation (control group) were compared. Results showed that the goats fed with 0.03% and 0.05% NAC had similar litter size, birth weight, nitric oxide (NO), sex hormones and amino acids levels compared with the goats of the control group. However, feeding with 0.07% NAC supplementation from day 0 to day 30 of gestation remarkably increased the litter size of goats. The goats of the 0.07% NAC group presented increased levels of NO relative to the control group, but their sex hormones and amino acids showed no differences. Comparative transcriptome analysis identified 207 differentially expressed genes (DEGs) in the endometrium between the control and the 0.07% NAC groups. These DEGs included 146 upregulated genes and 61 downregulated genes in the 0.07% NAC group. They were primarily involved in the cellular response to toxic substances, oxidoreductase activity, immune receptor activity, signalling receptor binding, cytokine-cytokine receptor interactions, PI3K-Akt signalling pathway and PPAR signalling pathway. In conclusion, results showed that dietary 0.07% NAC supplementation exerted a beneficial effect on the survival of goat embryos at the early pregnancy stage. Such positive outcome might be due to the increased NO production and affected expression of genes involved in the anti-inflammation pathways of the endometrium.

Antioxidant Effects of N-Acetylcysteine Prevent Programmed Metabolic Disease in Mice

An adverse maternal in utero and lactation environment can program offspring for increased risk for metabolic disease. The aim of this study was to determine whether N-acetylcysteine (NAC), an anti-inflammatory antioxidant, attenuates programmed susceptibility to obesity and insulin resistance in offspring of mothers on a high-fat diet (HFD) during pregnancy. CD1 female mice were acutely fed a standard breeding chow or HFD. NAC was added to the drinking water (1 g/kg) of the treatment cohorts from embryonic day 0.5 until the end of lactation. NAC treatment normalized HFD-induced maternal weight gain and oxidative stress, improved the maternal lipidome, and prevented maternal leptin resistance. These favorable changes in the in utero environment normalized postnatal growth, decreased white adipose tissue (WAT) and hepatic fat, improved glucose and insulin tolerance and antioxidant capacity, reduced leptin and insulin, and increased adiponectin in HFD offspring. The lifelong metabolic improvements in the offspring were accompanied by reductions in proinflammatory gene expression in liver and WAT and increased thermogenic gene expression in brown adipose tissue. These results, for the first time, provide a mechanistic rationale for how NAC can prevent the onset of metabolic disease in the offspring of mothers who consume a typical Western HFD.

Neonatal hair profiling reveals a metabolic phenotype of monochorionic twins with selective intrauterine growth restriction and abnormal umbilical artery flow

BACKGROUND

Selective intrauterine fetal growth restriction (sIUGR) in monochorionic diamniotic twins, especially types 2&3 with abnormal umbilical artery Doppler, results in increased risk of fetal/perinatal mortality and postnatal disability. We investigate whether the hair metabolome profiles of neonates were associated with the pathophysiological differences across the different clinical forms of sIUGR in twins.

METHODS

Hair samples were collected at delivery from 10 pairs of type 1 sIUGR twins, 8 pairs of types 2&3 sIUGR twins, and 11 pairs of twins without sIUGR. The hair metabolome was characterized using gas chromatography-mass spectrometry.

RESULTS

Our results demonstrated that the hair metabolite profiles of the different sIUGR subclinical forms were associated with the averaged fetal growth rate after 28 weeks of gestation but not with birthweight. The hair profiles were capable of discriminating type2&3 sIUGR twins from twins without sIUGR. In particular, the metabolites 2-aminobutyric acid, cysteine, alanine, and tyrosine all displayed areas under the receiver operating characteristic curve were above 0.9. The metabolic pathway analysis highlighted the associations of sIUGR twins with abnormal umbilical artery flow with increased metabolites from a nutrient depletion pathway, glutathione metabolism, and nerve development.

CONCLUSION

This study offers novel insight into the severity of intrauterine ischemia and hypoxia for T2&3 sIUGR twins, through evaluation of the neonatal hair metabolome.

Effects of dimethylglycine sodium salt supplementation on growth performance, hepatic antioxidant capacity, and mitochondria-related gene expression in weanling piglets born with low birth weight1

Dimethylglycine sodium salt (DMG-Na) has exhibited excellent advantages in animal experiments and human health. The present study aimed to investigate the effects of dietary supplementation with 0.1% DMG-Na on the growth performance, hepatic antioxidant capacity, and mRNA expression of mitochondria-related genes in low birth weight (LBW) piglets during weaning period. Sixteen piglets with normal birth weight (NBW) and 16 LBW piglets were fed either a basal diet or a 0.1% DMG-Na supplemented diet from age of 21 to 49 d. Blood and liver samples were collected at the end of the study. The results showed that compared with NBW piglets, LBW piglets exhibited greater (P < 0.05) alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase activities in the serum. LBW decreased (P < 0.05) the activity of glutathione peroxidase and increased (P < 0.05) the contents of malondialdehyde and H2O2 in liver. DMG-Na supplementation increased (P < 0.05) body weight gain, feed intake, and feed efficiency, decreased (P < 0.05) ALT and AST activities, and reduced the content of H2O2 in LBW piglets. LBW piglets had downregulated (P < 0.05) mRNA expression of thioredoxin 2, thioredoxin reductases 2, and nuclear respiratory factor-1 (Nrf1) in the liver. However, DMG-Na supplementation increased (P < 0.05) mRNA expression of Nrf1 in the liver. In conclusion, DMG-Na supplementation has beneficial effects in alleviating LBW-induced hepatic oxidative damage and changed mitochondrial genes expression levels, which is associated with increased antioxidant enzyme activities and up-regulating mRNA gene abundance.

Adult vascular dysfunction in foetal growth-restricted guinea-pigs is associated with a neonate-adult switching in Nos3 DNA methylation

AIM

Foetal growth restriction (FGR) is associated with endothelial dysfunction and cardiovascular diseases in adult subjects. Early vascular remodelling and epigenetic changes occurring on key endothelial genes might precede this altered vascular function. Further, it has been proposed that oxidative stress during development may determine some of these epigenetic modifications. To address this issue, we studied the in vivo and ex vivo vascular function and Nos3 promoter DNA methylation in arteries from eight-month-old guinea-pig born from control, FGR-treated and FGR-NAC-treated pregnancies.

METHODS

Femoral and carotid arteries in vivo vascular function were determined by Doppler, whilst ex vivo vascular function and biomechanical properties were assessed by wire myography. Levels of eNOS mRNA and site-specific DNA methylation in Nos3 promoter in aorta endothelial cells (AEC) were determined by qPCR and pyrosequencing respectively.

RESULTS

FGR adult showed an increased femoral vascular resistance (P < .05), stiffness (P < .05) and arterial remodelling (P < .01), along with an impaired NO-mediated relaxation (P < .001). These effects were prevented by maternal treatment with NAC. Endothelial-NOS mRNA levels were decreased in FGR adult compared with control and FGR-NAC (P < .05), associated with increased DNA methylation levels (P < .01). Comparison of Nos3 DNA methylation in AEC showed a differential methylation pattern between foetal and adult guinea-pigs (P < .05).

CONCLUSION

Altogether, these data suggest that adult vascular dysfunction in the FGR does not result from early changes in Nos3 promoter DNA methylation, but from an altered vessel structure established during foetal development.

Epigenetic Modulation in the Initiation and Progression of Pulmonary Hypertension

Pulmonary hypertension (PH) is a severe disease with multiple etiologies. In addition to genetics, recent studies have revealed the epigenetic modulation in the initiation and progression of PH. In this review, we summarize the epigenetic mechanisms in the pathogenesis of PH, specifically, DNA methylation, histone modifications, and microRNAs. We further emphasize the diagnostic and therapeutic potential of these epigenetic hallmarks in PH. Finally, we highlight the developmental reprogramming in adult-onset PH because of adverse perinatal exposures such as intrauterine growth restriction and extrauterine growth restriction. Therefore, epigenetic modifications provide promise for the therapy and prevention of PH.

Premature Vascular Aging in Guinea Pigs Affected by Fetal Growth Restriction

Cardiovascular risk associated with fetal growth restriction (FGR) could result from an early impaired vascular function. However, whether this effect results in premature vascular aging has not been addressed. We studied the ex vivo reactivity of carotid and femoral arteries in fetal (near term), adults (eight months-old) and aged (16 months-old) guinea pigs in normal (control) and FGR offspring. Additionally, an epigenetic marker of vascular aging (i.e., LINE-1 DNA methylation) was evaluated in human umbilical artery endothelial cells (HUAEC) from control and FGR subjects. Control guinea pig arteries showed an increased contractile response (KCl-induced) and a progressive impairment of NO-mediated relaxing responses as animals get older. FGR was associated with an initial preserved carotid artery reactivity as well as a later significant impairment in NO-mediated responses. Femoral arteries from FGR fetuses showed an increased contractility but a decreased relaxing response compared with control fetuses, and both responses were impaired in FGR-adults. Finally, FGR-HUAEC showed decreased LINE-1 DNA methylation compared with control-HUAEC. These data suggest that the aging of vascular function occurs by changes in NO-mediated responses, with limited alterations in contractile capacity. Further, these effects are accelerated and imposed at early stages of development in subjects exposed to a suboptimal intrauterine environment.

Effects of n-acetyl-cysteine supplementation in late gestational diet on maternal-placental redox status, placental NLRP3 inflammasome, and fecal microbiota in sows1

Although n-acetyl-cysteine (NAC) has been shown to efficiently alleviate oxidative stress, inflammatory response, and alter gut microbiota, little attention has been focused on their interactions with placental metabolic status of sows. The effects of NAC on the placental redox status, function, inflammasome, and fecal microbiota in sows were explored to clarify the correlation between the fecal microbiota and placenta. Sows were divided into either the control group or the NAC group which received dietary 0.5% NAC supplementation from day 85 of gestation to delivery. Plasma redox status, placental growth factors, nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome, fecal microbial metabolites, and communities were evaluated. Compared with the control group, although NAC did not ameliorate reproductive performance of sows (P > 0.05), it significantly improved maternal-placental health, which was accompanied by increased activities of glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD), decreased level of malondialdehyde (MDA), and lowered expression of interleukin (IL)-1β and IL-18 through inhibiting NLRP3 inflammasome (P < 0.05). Additionally, NAC significantly increased placental insulin-like growth factors (IGFs) and E-cadherin contents (P < 0.05), elevated the expression of genes involved in angiogenesis and amino acids transporters (P < 0.05), and decreased the microtubule-associated protein light chain 3B (LC3B) and Beclin-1 protein expression (P < 0.05). Furthermore, NAC increased the relative abundances of fecal Prevotella, Clostridium cluster XIVa, and Roseburial/Eubacterium rectale (P < 0.05), which were negatively correlated with placental NLRP3 and positively with solute carrier family 7, member 8 (Slc7a8; P < 0.05). In conclusion, NAC supplementation during late gestation alleviated maternal-placental oxidative stress and inflammatory response, improved placental function, and altered fecal microbial communities.

Oxidative Stress, Intrauterine Growth Restriction, and Developmental Programming of Type 2 Diabetes

Intrauterine growth restriction (IUGR) leads to reduced birth weight and the development of metabolic diseases such as Type 2 diabetes in adulthood. Mitochondria dysfunction and oxidative stress are commonly found in key tissues (pancreatic islets, liver, and skeletal muscle) of IUGR individuals. In this review, we explore the role of oxidative stress in IUGR-associated diabetes etiology.

New Therapeutic Implications of Endothelial Nitric Oxide Synthase (eNOS) Function/Dysfunction in Cardiovascular Disease

The Global Burden of Disease Study identified cardiovascular risk factors as leading causes of global deaths and life years lost. Endothelial dysfunction represents a pathomechanism that is associated with most of these risk factors and stressors, and represents an early (subclinical) marker/predictor of atherosclerosis. Oxidative stress is a trigger of endothelial dysfunction and it is a hall-mark of cardiovascular diseases and of the risk factors/stressors that are responsible for their initiation. Endothelial function is largely based on endothelial nitric oxide synthase (eNOS) function and activity. Likewise, oxidative stress can lead to the loss of eNOS activity or even “uncoupling” of the enzyme by adverse regulation of well-defined “redox switches” in eNOS itself or up-/down-stream signaling molecules. Of note, not only eNOS function and activity in the endothelium are essential for vascular integrity and homeostasis, but also eNOS in perivascular adipose tissue plays an important role for these processes. Accordingly, eNOS protein represents an attractive therapeutic target that, so far, was not pharmacologically exploited. With our present work, we want to provide an overview on recent advances and future therapeutic strategies that could be used to target eNOS activity and function in cardiovascular (and other) diseases, including life style changes and epigenetic modulations. We highlight the redox-regulatory mechanisms in eNOS function and up- and down-stream signaling pathways (e.g., tetrahydrobiopterin metabolism and soluble guanylyl cyclase/cGMP pathway) and their potential pharmacological exploitation.

Guinea pig models for translation of the developmental origins of health and disease hypothesis into the clinic

Over 30 years ago Professor David Barker first proposed the theory that events in early life could explain an individual's risk of non-communicable disease in later life: the developmental origins of health and disease (DOHaD) hypothesis. During the 1990s the validity of the DOHaD hypothesis was extensively tested in a number of human populations and the mechanisms underpinning it characterised in a range of experimental animal models. Over the past decade, researchers have sought to use this mechanistic understanding of DOHaD to develop therapeutic interventions during pregnancy and early life to improve adult health. A variety of animal models have been used to develop and evaluate interventions, each with strengths and limitations. It is becoming apparent that effective translational research requires that the animal paradigm selected mirrors the tempo of human fetal growth and development as closely as possible so that the effect of a perinatal insult and/or therapeutic intervention can be fully assessed. The guinea pig is one such animal model that over the past two decades has demonstrated itself to be a very useful platform for these important reproductive studies. This review highlights similarities in the in utero development between humans and guinea pigs, the strengths and limitations of the guinea pig as an experimental model of DOHaD and the guinea pig's potential to enhance clinical therapeutic innovation to improve human health.

Progressive uterine artery occlusion in the Guinea pig leads to defects in placental structure that relate to fetal growth

Intrauterine growth restriction (IUGR) is a common obstetric complication with immediate and life-long consequences for offspring health. Yet the mechanisms underlying its aetiology require elucidation. Recent work in the guinea pig shows that progressive uterine artery occlusion induced IUGR and vascular dysfunction in pups. Here we explore the extent to which uterine artery occlusion influences fetal outcomes via impacts on placental morphology. Our study demonstrates that uterine artery occlusion severely compromised both the labyrinth exchange zone (increased fibrosis and reduced vascularisation, trophoblast volume, surface area and diffusing capacity) and interlobium zone (increased apoptosis), which likely contributed to the IUGR observed.

Arginase upregulation and eNOS uncoupling contribute to impaired endothelium-dependent vasodilation in a rat model of intrauterine growth restriction

Individuals born after intrauterine growth restriction (IUGR) are at increased risk of developing cardiovascular diseases in adulthood, notably hypertension (HTN). Alterations in the vascular system, particularly impaired endothelium-dependent vasodilation, may play an important role in long-term effects of IUGR. Whether such vascular dysfunction precedes HTN has not been fully established in individuals born after IUGR. Moreover, the intimate mechanisms of altered endothelium-dependent vasodilation remain incompletely elucidated. We therefore investigated, using a rat model of IUGR, whether impaired endothelium-dependent relaxation precedes the development of HTN and whether key components of the l-arginine-nitric oxide (NO) pathway are involved in its pathogenesis. Pregnant rats were fed with a control (CTRL, 23% casein) or low-protein diet (LPD, 9% casein) to induce IUGR. Systolic blood pressure (SBP) was measured by tail-cuff plethysmography in 5- and 8-wk-old male offspring. Aortic rings were isolated to investigate relaxation to acetylcholine, NO production, endothelial NO synthase (eNOS) protein content, arginase activity, and superoxide anion production. SBP was not different at 5 wk but significantly increased in 8-wk-old offspring of maternal LPD (LP) versus CTRL offspring. In 5-wk-old LP versus CTRL males, endothelium-dependent vasorelaxation was significantly impaired but restored by preincubation with l-arginine or the arginase inhibitor S-(2-boronoethyl)-l-cysteine; NO production was significantly reduced but restored by l-arginine pretreatment; total eNOS protein, dimer-to-monomer ratio, and arginase activity were significantly increased; superoxide anion production was significantly enhanced but normalized by pretreatment with the NO synthase inhibitor N^ω-nitro-l-arginine. In this model, IUGR leads to early-impaired endothelium-dependent vasorelaxation, resulting from arginase upregulation and eNOS uncoupling, which precedes the development of HTN.

Role of glutathione in the regulation of epigenetic mechanisms in disease

Epigenetics is a rapidly growing field that studies gene expression modifications not involving changes in the DNA sequence. Histone H3, one of the basic proteins in the nucleosomes that make up chromatin, is S-glutathionylated in mammalian cells and tissues, making Gamma-L-glutamyl-L-cysteinylglycine, glutathione (GSH), a physiological antioxidant and second messenger in cells, a new post-translational modifier of the histone code that alters the structure of the nucleosome. However, the role of GSH in the epigenetic mechanisms likely goes beyond a mere structural function. Evidence supports the hypothesis that there is a link between GSH metabolism and the control of epigenetic mechanisms at different levels (i.e., substrate availability, enzymatic activity for DNA methylation, changes in the expression of microRNAs, and participation in the histone code). However, little is known about the molecular pathways by which GSH can control epigenetic events. Studying mutations in enzymes involved in GSH metabolism and the alterations of the levels of cofactors affecting epigenetic mechanisms appears challenging. However, the number of diseases induced by aberrant epigenetic regulation is growing, so elucidating the intricate network between GSH metabolism, oxidative stress and epigenetics could shed light on how their deregulation contributes to the development of neurodegeneration, cancer, metabolic pathologies and many other types of diseases.

Intrauterine growth restriction-induced deleterious adaptations in endothelial progenitor cells: possible mechanism to impair endothelial function

Intrauterine growth restriction (IUGR) can induce deleterious changes in the modulatory ability of the vascular endothelium, contributing to an increased risk of developing cardiovascular diseases in the long term. However, the mechanisms involved are not fully understood. Emerging evidence has suggested the potential role of endothelial progenitor cells (EPCs) in vascular health and repair. Therefore, we aimed to evaluate the effects of IUGR on vascular reactivity and EPCs derived from the peripheral blood (PB) and bone marrow (BM) in vitro. Pregnant Wistar rats were fed an ad libitum diet (control group) or 50% of the ad libitum diet (restricted group) throughout gestation. We determined vascular reactivity, nitric oxide (NO) concentration, and endothelial nitric oxide synthase (eNOS) protein expression by evaluating the thoracic aorta of adult male offspring from both groups (aged: 19-20 weeks). Moreover, the amount, functional capacity, and senescence of EPCs were assessed in vitro. Our results indicated that IUGR reduced vasodilation via acetylcholine in aorta rings, decreased NO levels, and increased eNOS phosphorylation at Thr495. The amount of EPCs was similar between both groups; however, IUGR decreased the functional capacity of EPCs from the PB and BM. Furthermore, the senescence process was accelerated in BM-derived EPCs from IUGR rats. In summary, our findings demonstrated the deleterious changes in EPCs from IUGR rats, such as reduced EPC function and accelerated senescence in vitro. These findings may contribute towards elucidating the possible mechanisms involved in endothelial dysfunction induced by fetal programming.

Endothelial dysfunction in individuals born after fetal growth restriction: cardiovascular and renal consequences and preventive approaches

Individuals born after intrauterine growth restriction (IUGR) have an increased risk of perinatal morbidity/mortality, and those who survive face long-term consequences such as cardiovascular-related diseases, including systemic hypertension, atherosclerosis, coronary heart disease and chronic kidney disease. In addition to the demonstrated long-term effects of decreased nephron endowment and hyperactivity of the hypothalamic-pituitary-adrenal axis, individuals born after IUGR also exhibit early alterations in vascular structure and function, which have been identified as key factors of the development of cardiovascular-related diseases. The endothelium plays a major role in maintaining vascular function and homeostasis. Therefore, it is not surprising that impaired endothelial function can lead to the long-term development of vascular-related diseases. Endothelial dysfunction, particularly impaired endothelium-dependent vasodilation and vascular remodeling, involves decreased nitric oxide (NO) bioavailability, impaired endothelial NO synthase functionality, increased oxidative stress, endothelial progenitor cells dysfunction and accelerated vascular senescence. Preventive approaches such as breastfeeding, supplementation with folate, vitamins, antioxidants, L-citrulline, L-arginine and treatment with NO modulators represent promising strategies for improving endothelial function, mitigating long-term outcomes and possibly preventing IUGR of vascular origin. Moreover, the identification of early biomarkers of endothelial dysfunction, especially epigenetic biomarkers, could allow early screening and follow-up of individuals at risk of developing cardiovascular and renal diseases, thus contributing to the development of preventive and therapeutic strategies to avert the long-term effects of endothelial dysfunction in infants born after IUGR.

Fetal Growth Restriction Induces Heterogeneous Effects on Vascular Biomechanical and Functional Properties in Guinea Pigs (Cavia porcellus)

Aim: Fetal growth restriction (FGR) is associated with a variety of cardiometabolic diseases in adulthood which could involve remodeling processes of the vascular walls that could start in the fetal period. However, there is no consensus whether this remodeling affects in a similar way the whole vascular system. We aimed to determine the effects of FGR on the vasoactive and biomechanical properties of umbilical and systemic vessels in fetal guinea pigs.

Methods: FGR was induced by implanting ameroid occluders at mid-gestation in uterine arteries of pregnant guinea pigs, whilst the control group was exposed to simulated surgery. At the term of gestation, systemic arteries (aorta, carotid and femoral) and umbilical vessels were isolated to determine ex vivo contractile and biomechanical responses (stretch-stress until rupture) on a wire myograph, as well as opening angle and residual stresses. Histological characteristics in tissue samples were measured by van Gieson staining.

Results: Aorta and femoral arteries from FGR showed an increased in biomechanical markers of stiffness (p < 0.01), contractile capacity (p < 0.05) and relative media thickness (p < 0.01), but a reduced internal diameter (p < 0.001), compared with controls. There were no differences in the biomechanical properties of carotid and umbilical from control and FGR fetuses, but FGR umbilical arteries had a decreased contractile response to KCl (p < 0.05) along with a reduced relative media thickness (p < 0.05).

Conclusion: Altogether, these changes in functional, mechanical and morphological properties suggest that FGR is associated with a heterogeneous pro-constrictive vascular remodeling affecting mainly the lower body fetal arteries. These effects would be set during a pathologic pregnancy in order to sustain the fetal blood redistribution in the FGR and may persist up to adulthood increasing the risk of a cardiovascular disease.