Maternal treatment with a placental-targeted antioxidant (MitoQ) impacts offspring cardiovascular function in a rat model of prenatal hypoxia

Targeting oxidative stress in preeclampsia

Preeclampsia is a complex condition characterized by elevated blood pressure and organ damage involving kidneys or liver, resulting in significant morbidity and mortality for both the mother and the fetus. Increasing evidence suggests that oxidative stress, often caused by mitochondrial dysfunction within fetal trophoblast cells may play a major role in the development and progression of preeclampsia. Oxidative stress occurs as a result of an imbalance between the production of reactive oxygen species (ROS) and the capacity of antioxidant defenses, which can lead to placental cellular damage and endothelial cell dysfunction. Targeting oxidative stress appears to be a promising therapeutic approach that has the potential to improve both short- and long-term maternal and fetal outcomes, thus reducing the global burden of preeclampsia. The purpose of this review is to provide a comprehensive account of the mechanisms of oxidative stress in preeclampsia. Furthermore, it also examines potential interventions for reducing oxidative stress in preeclampsia, including natural antioxidant supplements, lifestyle modifications, mitochondrial targeting antioxidants, and pharmacological agents.A better understanding of the mechanism of action of proposed therapeutic strategies targeting oxidative stress is essential for the identification of companion biomarkers and personalized medicine approaches for the development of effective treatments of preeclampsia.

Prenatal Origins of Obstructive Airway Disease: Starting on the Wrong Trajectory?

From the results of well-performed population health studies, we now have excellent data demonstrating that deficits in adult lung function may be present early in life, possibly as a result of developmental disorders, incurring a lifelong risk of obstructive airway diseases such as asthma and chronic obstructive pulmonary disease. Suboptimal fetal development results in intrauterine growth restriction and low birth weight at term (an outcome distinct from preterm complications), which are associated with subsequent obstructive disease. Numerous prenatal exposures and disorders compromise fetal development and these are summarized herein. Various physiological, structural, and mechanical abnormalities may result from prenatal disruption, including changes to airway smooth muscle structure-function, goblet cell biology, airway stiffness, geometry of the bronchial tree, lung parenchymal structure and mechanics, respiratory skeletal muscle contraction, and pulmonary inflammation. The literature therefore supports the need for early life intervention to prevent or correct growth defects, which may include simple nutritional or antioxidant therapy. © 2024 American Physiological Society. Compr Physiol 14:5729-5762, 2024.

Maladaptive cardiomyocyte calcium handling in adult offspring of hypoxic pregnancy: protection by antenatal maternal melatonin

Chronic fetal hypoxia is one of the most common complications of pregnancy and can programme cardiac abnormalities in adult offspring including ventricular remodelling, diastolic dysfunction and sympathetic dominance. However, the underlying mechanisms at the level of the cardiomyocyte are unknown, preventing the identification of targets for therapeutic intervention. Therefore, we aimed to link echocardiographic data with cardiomyocyte function to reveal cellular mechanism for cardiac dysfunction in rat offspring from hypoxic pregnancy. Further, we investigated the potential of maternal treatment with melatonin as antenatal antioxidant therapy. Wistar rats were randomly allocated into normoxic (21% O2) or hypoxic (13% O2) pregnancy with or without melatonin treatment (5 µg/ml; normoxic melatonin in the maternal drinking water from gestational day 6 to 20 (term = 22 days). After delivery, male and female offspring were maintained to adulthood (16 weeks). Cardiomyocytes were isolated from the left and right ventricles, and calcium (Ca2+) handling was investigated in field-stimulated myocytes. Systolic and diastolic function was negatively impacted in male and female offspring of hypoxic pregnancy demonstrating biventricular systolic and diastolic dysfunction and compensatory increases in cardiac output. Ca2+ transients from isolated cardiomyocytes in offspring of both sexes in hypoxic pregnancy displayed diastolic dysfunction with a reduced rate of [Ca2+]i recovery. Cardiac and cardiomyocyte dysfunction in male and female adult offspring was ameliorated by maternal antenatal treatment with melatonin in hypoxic pregnancy. Therefore, cardiomyocyte Ca2+ mishandling provides a cellular mechanism explaining functional deficits in hearts of male and female offspring in pregnancies complicated by chronic fetal hypoxia. KEY POINTS: This study identified significant changes in Ca2+ handling within cardiomyocytes isolated from offspring of hypoxic pregnancy including reduced systolic Ca2+ transients, impaired diastolic recovery of [Ca2+]i and a greater increase in systolic [Ca2+]i amplitude to β-adrenergic stimulation. These changes in cardiomyocyte Ca2+ handling help to explain dysregulation of biventricular systolic and diastolic dysfunction determined by echocardiography. The data show protection against maladaptive cardiomyocyte calcium handling and thereby improvement in cardiac function in adult offspring of hypoxic pregnancy treated with melatonin with doses lower than those recommended for overcoming jet lag in humans. Melatonin treatment alone in healthy pregnancy did cause some alterations in cardiac structure. Therefore, maternal treatment with melatonin should only be given to pregnancies affected by chronic fetal hypoxia.

The Use of Antioxidants for Cardiovascular Protection in Fetal Growth Restriction: A Systematic Review

Fetal growth restriction (FGR) increases the risk of cardiovascular disease. There are currently no treatment options available; however, antioxidants have shown potential to improve cardiovascular deficits associated with FGR. This systematic review aimed to determine whether antenatal antioxidant intervention can effectively protect the developing cardiovascular system in FGR. We searched for interventional studies that used an antenatal antioxidant intervention to improve cardiac and/or vascular outcomes in FGR published between 01/1946 and 09/2024 using MEDLINE and Embase (PROSPERO: CRD42024503756). The risk of bias was assessed with SYRCLE. The studies were assessed for cardiovascular protection based on the percentage of cardiac and/or vascular deficits that were restored with the antioxidant treatment. Studies were characterised as showing strong cardiovascular protection (≥50% restoration), mild cardiovascular protection (>0% but <50% restoration), an antioxidant-only effect (this did not include control group which showed a change with antioxidant intervention compared to FGR) or no cardiovascular protection (0% restoration). Thirty-eight publications met the inclusion criteria, encompassing 43 studies and investigating 15 antioxidant interventions. Moreover, 29/43 studies (71%) reported the restoration of at least one cardiac or vascular deficit with antioxidant intervention, and 21/43 studies (51%) were classified as strong cardiovascular protection. An ex vivo analysis of the arterial function in seven studies revealed endothelial dysfunction in growth-restricted offspring and antioxidant interventions restored the endothelial function in all cases. Additionally, four studies demonstrated that antioxidants reduced peroxynitrite-mediated oxidative stress. Notably, only 13/43 studies (32%) delayed antioxidant administration until after the induction of FGR. Antenatal antioxidant interventions show promise for providing cardiovascular protection in FGR. Melatonin was the most frequently studied intervention followed by nMitoQ, vitamin C and N-acetylcysteine, all of which demonstrated a strong capacity to reduce oxidative stress and improve nitric oxide bioavailability in the cardiovascular system of growth-restricted offspring; however, this systematic review highlights critical knowledge gaps and inconsistencies in preclinical research, which hinder our ability to determine which antioxidant treatments are currently suitable for clinical translation.

Preterm Birth and Kidney Health: From the Womb to the Rest of Life

Chronic kidney disease (CKD) is a widespread condition often resulting from multiple factors, including maternal influences. These risk factors not only heighten the likelihood of developing CKD but increase the risk of a preterm birth. Adverse events during nephrogenesis can disrupt kidney development, leading to a reduced number of nephrons. As survival rates for preterm infants improve, more individuals are living into adulthood, thereby elevating their risk of CKD later in life. This review aims to explore the connections between preterm birth, kidney development, and the increased risk of CKD, while proposing practical solutions for the future through a multidisciplinary approach. We examine human studies linking preterm birth to negative kidney outcomes, summarize animal models demonstrating kidney programming and reduced nephron numbers, and consolidate knowledge on common mechanisms driving kidney programming. Additionally, we discuss factors in the postnatal care environment that may act as secondary insults contributing to CKD risk, such as acute kidney injury (AKI), the use of nephrotoxic drugs, preterm nutrition, and catch-up growth. Finally, we outline recommendations for action, emphasizing the importance of avoiding modifiable risk factors and implementing early CKD screening for children born preterm. Together, we can ensure that advancements in kidney health keep pace with improvements in preterm care.

Preeclampsia: A comprehensive review

Preeclampsia (PE) is a life-threatening disease of pregnancy and a prominent cause of neonatal and maternal mortality and morbidity. PE affects approximately 5-10% of pregnancies worldwide, posing significant risks to perinatal and maternal health. It is characterized by a variety of interconnected pathological cascades contributing to the stimulation of intravascular inflammation, oxidative stress (OS), endothelial cell activation, and syncytiotrophoblast stress that converge on a common pathway, ultimately resulting in disease progression. The present study was designed and executed to review the existing scientific literature, specifically focusing on the etiology (gestational diabetes mellitus and maternal obesity, insulin resistance, metabolic syndrome, maternal infection, periodontal disease, altered microbiome, and genetics), clinical presentations (hypertension, blood disorders, proteinuria, hepatic dysfunction, renal dysfunction, pulmonary edema, cardiac dysfunction, fetal growth restrictions, and eclampsia), therapeutic clinical biomarkers (creatinine, albuminuria, and cystatin C) along with their associations and mechanisms in PE. In addition, this study provides insights into the potential of nanomedicines for targeting these mechanisms for PE management and treatment. Inflammation, OS, proteinuria, and an altered microbiome are prominent biomarkers associated with progression and PE-related pathogenesis. Understanding the molecular mechanisms, exploring suitable markers, targeted interventions, comprehensive screening, and holistic strategies are critical to decreasing the incidence of PE and promoting maternal-fetal well-being. The present study comprehensively reviewed the etiology, clinical presentations, therapeutic biomarkers, and preventive potential of nanomedicines in the treatment and management of PE.

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.

Placental Methylglyoxal in Preeclampsia: Vascular and Biomarker Implications

BACKGROUND

Preeclampsia is a multifaceted syndrome that includes maternal vascular dysfunction. We hypothesize that increased placental glycolysis and hypoxia in preeclampsia lead to increased levels of methylglyoxal (MGO), consequently causing vascular dysfunction.

METHODS

Plasma samples and placentas were collected from uncomplicated and preeclampsia pregnancies. Uncomplicated placentas and trophoblast cells (BeWo) were exposed to hypoxia. The reactive dicarbonyl MGO and advanced glycation end products (Nε-(carboxymethyl)lysine [CML], Nε-(carboxyethyl)lysine [CEL], and MGO-derived hydroimidazolone [MG-H]) were quantified using liquid chromatography-tandem mass spectrometry. The activity of GLO1 (glyoxalase-1), that is, the enzyme detoxifying MGO, was measured. The impact of MGO on vascular function was evaluated using wire/pressure myography. The therapeutic potential of the MGO-quencher quercetin and mitochondrial-specific antioxidant mitoquinone mesylate (MitoQ) was explored.

RESULTS

MGO, CML, CEL, and MG-H2 levels were elevated in preeclampsia-placentas (+36%, +36%, +25%, and +22%, respectively). Reduced GLO1 activity was observed in preeclampsia-placentas (-12%) and hypoxia-exposed placentas (-16%). Hypoxia-induced MGO accumulation in placentas was mitigated by the MGO-quencher quercetin. Trophoblast cells were identified as the primary source of MGO. Reduced GLO1 activity was also observed in hypoxia-exposed BeWo cells (-26%). Maternal plasma concentrations of CML and the MGO-derived MG-H1 increased as early as 12 weeks of gestation (+16% and +17%, respectively). MGO impaired endothelial barrier function, an effect mitigated by MitoQ, and heightened vascular responsiveness to thromboxane A2.

CONCLUSIONS

This study reveals the accumulation of placental MGO in preeclampsia and upon exposure to hypoxia, demonstrates how MGO can contribute to vascular impairment, and highlights plasma CML and MG-H1 levels as promising early biomarkers for preeclampsia.

Sex-specific differences in the mechanisms for enhanced thromboxane A2-mediated vasoconstriction in adult offspring exposed to prenatal hypoxia

BACKGROUND

Prenatal hypoxia, a common pregnancy complication, leads to impaired cardiovascular outcomes in the adult offspring. It results in impaired vasodilation in coronary and mesenteric arteries of the adult offspring, due to reduced nitric oxide (NO). Thromboxane A2 (TxA2) is a potent vasoconstrictor increased in cardiovascular diseases, but its role in the impact of prenatal hypoxia is unknown. To prevent the risk of cardiovascular disease by prenatal hypoxia, we have tested a maternal treatment using a nanoparticle-encapsulated mitochondrial antioxidant (nMitoQ). We hypothesized that prenatal hypoxia enhances vascular TxA2 responses in the adult offspring, due to decreased NO modulation, and that this might be prevented by maternal nMitoQ treatment.

METHODS

Pregnant Sprague-Dawley rats received a single intravenous injection (100 µL) of vehicle (saline) or nMitoQ (125 µmol/L) on gestational day (GD)15 and were exposed to normoxia (21% O2) or hypoxia (11% O2) from GD15 to GD21 (term = 22 days). Coronary and mesenteric arteries were isolated from the 4-month-old female and male offspring, and vasoconstriction responses to U46619 (TxA2 analog) were evaluated using wire myography. In mesenteric arteries, L-NAME (pan-NO synthase (NOS) inhibitor) was used to assess NO modulation. Mesenteric artery endothelial (e)NOS, and TxA2 receptor expression, superoxide, and 3-nitrotyrosine levels were assessed by immunofluorescence.

RESULTS

Prenatal hypoxia resulted in increased U46619 responsiveness in coronary and mesenteric arteries of the female offspring, and to a lesser extent in the male offspring, which was prevented by nMitoQ. In females, there was a reduced impact of L-NAME in mesenteric arteries of the prenatal hypoxia saline-treated females, and reduced 3-nitrotyrosine levels. In males, L-NAME increased U46619 responses in mesenteric artery to a similar extent, but TxA2 receptor expression was increased by prenatal hypoxia. There were no changes in eNOS or superoxide levels.

CONCLUSIONS

Prenatal hypoxia increased TxA2 vasoconstrictor capacity in the adult offspring in a sex-specific manner, via reduced NO modulation in females and increased TP expression in males. Maternal placental antioxidant treatment prevented the impact of prenatal hypoxia. These findings increase our understanding of how complicated pregnancies can lead to a sex difference in the programming of cardiovascular disease in the adult offspring.

Mitochondrial Dysfunction in Endothelial Progenitor Cells: Unraveling Insights from Vascular Endothelial Cells

Endothelial dysfunction is associated with several lifestyle-related diseases, including cardiovascular and neurodegenerative diseases, and it contributes significantly to the global health burden. Recent research indicates a link between cardiovascular risk factors (CVRFs), excessive production of reactive oxygen species (ROS), mitochondrial impairment, and endothelial dysfunction. Circulating endothelial progenitor cells (EPCs) are recruited into the vessel wall to maintain appropriate endothelial function, repair, and angiogenesis. After attachment, EPCs differentiate into mature endothelial cells (ECs). Like ECs, EPCs are also susceptible to CVRFs, including metabolic dysfunction and chronic inflammation. Therefore, mitochondrial dysfunction of EPCs may have long-term effects on the function of the mature ECs into which EPCs differentiate, particularly in the presence of endothelial damage. However, a link between CVRFs and impaired mitochondrial function in EPCs has hardly been investigated. In this review, we aim to consolidate existing knowledge on the development of mitochondrial and endothelial dysfunction in the vascular endothelium, place it in the context of recent studies investigating the consequences of CVRFs on EPCs, and discuss the role of mitochondrial dysfunction. Thus, we aim to gain a comprehensive understanding of mechanisms involved in EPC deterioration in relation to CVRFs and address potential therapeutic interventions targeting mitochondrial health to promote endothelial function.

Advance in placenta drug delivery: concern for placenta-originated disease therapy

In the therapy of placenta-originated diseases during pregnancy, the main challenges are fetal exposure to drugs, which can pass through the placenta and cause safety concerns for fetal development. The design of placenta-resident drug delivery system is an advantageous method to minimize fetal exposure as well as reduce adverse maternal off-target effects. By utilizing the placenta as a biological barrier, the placenta-resident nanodrugs could be trapped in the local placenta to concentrate on the treatment of this abnormal originated tissue. Therefore, the success of such systems largely depends on the placental retention capacity. This paper expounds on the transport mechanism of nanodrugs in the placenta, analyzes the factors that affect the placental retention of nanodrugs, and summarizes the advantages and concerns of current nanoplatforms in the treatment of placenta-originated diseases. In general, this review aims to provide a theoretical basis for the construction of placenta-resident drug delivery systems, which will potentially enable safe and efficient clinical treatment for placenta-originated diseases in the future.

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.

Sex-Specific Effects of Prenatal Hypoxia and a Placental Antioxidant Treatment on Cardiac Mitochondrial Function in the Young Adult Offspring

Prenatal hypoxia is associated with placental oxidative stress, leading to impaired fetal growth and an increased risk of cardiovascular disease in the adult offspring; however, the mechanisms are unknown. Alterations in mitochondrial function may result in impaired cardiac function in offspring. In this study, we hypothesized that cardiac mitochondrial function is impaired in adult offspring exposed to intrauterine hypoxia, which can be prevented by placental treatment with a nanoparticle-encapsulated mitochondrial antioxidant (nMitoQ). Cardiac mitochondrial respiration was assessed in 4-month-old rat offspring exposed to prenatal hypoxia (11% O2) from gestational day (GD)15-21 receiving either saline or nMitoQ on GD 15. Prenatal hypoxia did not alter cardiac mitochondrial oxidative phosphorylation capacity in the male offspring. In females, the NADH + succinate pathway capacity decreased by prenatal hypoxia and tended to be increased by nMitoQ. Prenatal hypoxia also decreased the succinate pathway capacity in females. nMitoQ treatment increased respiratory coupling efficiency in prenatal hypoxia-exposed female offspring. In conclusion, prenatal hypoxia impaired cardiac mitochondrial function in adult female offspring only, which was improved with prenatal nMitoQ treatment. Therefore, treatment strategies targeting placental oxidative stress in prenatal hypoxia may reduce the risk of cardiovascular disease in adult offspring by improving cardiac mitochondrial function in a sex-specific manner.

Nanomedicines: An approach to treat placental insufficiency and the current challenges

INTRODUCTION

Preeclampsia and fetal growth restriction are common pregnancy complications that significantly impact perinatal health and offspring development later in life. The origin of these complex syndromes overlap in placental insufficiency. Progress in developing treatments for maternal, placental or fetal health is mainly limited by the risk of maternal and fetal toxicity. Nanomedicines are a promising approach to safely treat pregnancy complications since they can regulate drug interaction with the placenta to enhance efficacy of the treatment while minimizing exposure of the fetus.

METHODS

This narrative review discusses the current developments and challenges of nanomedicines during pregnancy with a focus on preclinical models of placenta insufficiency syndromes. Firstly, we outline the safety requirements and potential therapeutic maternal and placental targets. Secondly, we review the prenatal therapeutic effects of the nanomedicines that have been tested in experimental models of placental insufficiency syndromes.

RESULTS

The majority of liposomes and polymeric drug delivery system show promising results regarding the prevention of trans-placental passage nanomedicines in uncomplicated and complicated pregnancies. The others two studied classes, quantum dots and silicon nanoparticles, have been investigated to a limited extent in placental insufficiency syndromes. Characteristics of the nanoparticles such as charge, size, and timing of administration have been shown to influence the trans-placental passage. The few available preclinical therapeutic studies on placental insufficiency syndromes predominantly show beneficial effects of nanomedicines on both maternal and fetal health, but demonstrate contradicting results on placental health. Interpretation of results in this field is complicated by the fact that results are influenced by the choice of animal species and model, gestational age, placental maturity and integrity, and nanoparticle administration route.

CONCLUSION

Nanomedicines form a promising therapeutic approach during (complicated) pregnancies mainly by reducing fetal toxicity and regulating drug interaction with the placenta. Different nanomedicines have been proven to effectively prevent trans-placental passage of encapsulated agents. This can be expected to dramatically reduce risks for fetal adverse effects. Furthermore, a number of these nanomedicines positively impacted maternal and fetal health in animal models for placental insufficiency. Demonstrating that effective drug concentrations can be reached in the target tissue. While these first animal studies are encouraging, more research is needed to better understand the influence of the pathophysiology of this multi-factorial disease before implementation in clinical practice can be considered. Therefore, extensive evaluation of safety and efficacy of these targeted nanoparticles is needed within multiple animal, in vitro, and/or ex vivo models. This may be complemented by diagnostic tools to assess the disease status to identify the best time to initiate treatment. Together these investigations should contribute to building confidence in the safety of nanomedicines for treating mother and child, as safety has, understandably, the highest priority in this sensitive patient groups.

TET2 confers a mechanistic link of microRNA-210 and mtROS in hypoxia-suppressed spontaneous transient outward currents in uterine arteries of pregnant sheep

Hypoxia during pregnancy impairs uterine vascular adaptation via microRNA-210 (miR-210)-mediated mitochondrial dysfunction and mitochondrial reactive oxygen species (mtROS) generation. TET methylcytosine dioxygenase 2 (TET2) participates in regulating inflammation and oxidative stress and its deficiency contributes to the pathogenesis of multiple cardiovascular diseases. Thus, we hypothesize a role of TET2 in hypoxia/miR-210-mediated mtROS suppressing spontaneous transient outward currents (STOCs) in uterine arteries. We found that gestational hypoxia downregulated TET2 in uterine arteries of pregnant sheep and TET2 was a target of miR-210. Knockdown of TET2 with small interfering RNAs suppressed mitochondrial respiration, increased mtROS, inhibited STOCs and elevated myogenic tone. By contrast, overexpression of TET2 negated hypoxia- and miR-210-induced mtROS. The effects of TET2 knockdown in uterine arteries on mtROS, STOCs and myogenic contractions were blocked by the mitochondria-targeted antioxidant MitoQ. In addition, the recovery effects of inhibiting endogenous miR-210 with miR-210-LNA on hypoxia-induced suppression of STOCs and augmentation of myogenic tone were reversed by TET2 knockdown in uterine arteries. Together, our study reveals a novel mechanistic link between the miR-210-TET2-mtROS pathway and inhibition of STOCs and provides new insights into the understanding of uterine vascular maladaptation in pregnancy complications associated with gestational hypoxia. KEY POINTS: Gestational hypoxia downregulates TET methylcytosine dioxygenase 2 (TET2) in uterine arteries of pregnant sheep. TET2 is a downstream target of microRNA-210 (miR-210) and miR-210 mediates hypoxia-induced TET2 downregulation. Knockdown of TET2 in uterine arteries recapitulates the effect of hypoxia and miR-210 and impairs mitochondrial bioenergetics and increases mitochondrial reactive oxygen species (mtROS) . Overexpression of TET2 negates the effect of hypoxia and miR-210 on increasing mtROS. TET2 knockdown reiterates the effect of hypoxia and miR-210 and suppresses spontaneous transient outward currents (STOCs) and elevates myogenic tone, and these effects are blocked by MitoQ. Knockdown of TET2 reverses the miR-210-LNA-induced reversal of the effects of hypoxia on STOCs and myogenic tone in uterine arteries.

Growth Restriction in Preeclampsia: Lessons from Animal Models

Preeclampsia remains a major health concern for mother and child. Yet, treatment options remain limited to early delivery. Placental dysfunction in preeclampsia occurs in response to an increase in oxidative stress and inflammatory cytokines with vasoactive and anti-angiogenic factors contributing to impaired maternal and fetal health. Moreover, recent studies indicate a potential role for epigenetic mediators in the pathophysiology of placental ischemia. Numerous animal models are utilized to explore the pathogenesis of preeclampsia and fetal growth restriction. This review provides a brief overview of recent progress in preclinical studies regarding potential therapeutic targets for the treatment and prevention of preeclampsia with an emphasis on fetal growth restriction and the fetal programming of increased cardiovascular risk.

Spermidine Alleviates Intrauterine Hypoxia-Induced Offspring Newborn Myocardial Mitochondrial Damage in Rats by Inhibiting Oxidative Stress and Regulating Mitochondrial Quality Control

Background

Intrauterine hypoxia (IUH) increases the risk of cardiovascular diseases in offspring. As a reactive oxygen species (ROS) scavenger, polyamine spermidine (SPD) is essential for embryonic and fetal survival and growth. However, further studies on the SPD protection and mechanisms for IUH-induced heart damage in offspring are required.

Objectives

This study aimed to investigate the preventive effects of prenatal SPD treatment on IUH-induced heart damage in newborn offspring rats and its underlying mitochondrial-related mechanism.

Methods

The rat model of IUH was established by exposure to 10% O₂ seven days before term. Meanwhile, for seven days, the pregnant rats were given SPD (5 mg.kg^-1.d^-1; ip). The one-day offspring rats were sacrificed to assess several parameters, including growth development, heart damage, cardiomyocytes proliferation, myocardial oxidative stress, cell apoptosis, and mitochondrial function, and have mitochondrial quality control (MQC), including mitophagy, mitochondrial biogenesis, and mitochondrial fusion/fission. In in vitro experiments, primary cardiomyocytes were subjected to hypoxia with or without SPD for 24 hours.

Results

IUH decreased body weight, heart weight, cardiac Ki67 expression, the activity of SOD, and the CAT and adenosine 5'-triphosphate (ATP) levels and increased the BAX/BCL2 expression, and TUNEL-positive nuclei numbers. Furthermore, IUH also caused mitochondrial structure abnormality, dysfunction, and decreased mitophagy (decreased number of mitophagosomes), declined mitochondrial biogenesis (decreased expression of SIRT-1, PGC-1α, NRF-2, and TFAM), and led to fission/fusion imbalance (increased percentage of mitochondrial fragments, increased DRP1 expression, and decreased MFN2 expression) in the myocardium. Surprisingly, SPD treatment normalized the variations in the IUH-induced parameters. Furthermore, SPD also prevented hypoxia-induced ROS accumulation, mitochondrial membrane potential decay, and the mitophagy decrease in cardiomyocytes.

Conclusion

Maternal SPD treatment caused IUH-induced heart damage in newborn offspring rats by improving the myocardial mitochondrial function via anti-oxidation and anti-apoptosis, and regulating MQC.

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.

MicroRNA-210-mediated mitochondrial reactive oxygen species confer hypoxia-induced suppression of spontaneous transient outward currents in ovine uterine arteries

Background and Purpose

Hypoxia during pregnancy is associated with increased uterine vascular resistance and elevated blood pressure both in women and female sheep. A previous study demonstrated a causal role of microRNA‐210 (miR‐210) in gestational hypoxia‐induced suppression of Ca²⁺ sparks/spontaneous transient outward currents (STOCs) in ovine uterine arteries, but the underlying mechanisms remain undetermined. We tested the hypothesis that miR‐210 perturbs mitochondrial metabolism and increases mitochondrial reactive oxygen species (mtROS) that confer hypoxia‐induced suppression of STOCs in uterine arteries.

Experimental Approach

Resistance‐sized uterine arteries were isolated from near‐term pregnant sheep and were treated ex vivo in normoxia and hypoxia (10.5% O₂) for 48 h.

Key Results

Hypoxia increased mtROS and suppressed mitochondrial respiration in uterine arteries, which were also produced by miR‐210 mimic to normoxic arteries and blocked by antagomir miR‐210‐LNA in hypoxic arteries. Hypoxia or miR‐210 mimic inhibited Ca²⁺ sparks/STOCs and increased uterine arterial myogenic tone, which were inhibited by the mitochondria‐targeted antioxidant MitoQ. Hypoxia and miR‐210 down‐regulated iron–sulfur cluster scaffold protein (ISCU) in uterine arteries and knockdown of ISCU via siRNAs suppressed mitochondrial respiration, increased mtROS, and inhibited STOCs. In addition, blockade of mitochondrial electron transport chain with antimycin and rotenone inhibited large‐conductance Ca²⁺‐activated K⁺ channels, decreased STOCs and increased uterine arterial myogenic tone.

Conclusion and Implications

This study demonstrates a novel mechanistic role for the miR‐210‐ISCU‐mtROS axis in inhibiting Ca²⁺ sparks/STOCs in the maladaptation of uterine arteries and provides new insights into the understanding of mitochondrial perturbations in the pathogenesis of pregnancy complications resulted from hypoxia.

Mitochondrial Dysfunction in the Pathogenesis of Preeclampsia

PURPOSE OF REVIEW

Preeclampsia complicates 5-10% of all pregnancies and is a leading cause of maternal and perinatal mortality and morbidity. The placenta plays a pivotal role in determining pregnancy outcome by supplying the fetus with oxygen and nutrients and by synthesizing hormones. Placental function is highly dependent on energy supplied by mitochondria. It is well-known that preeclampsia is originated from placental dysfunction, although the etiology of it remains elusive.

RECENT FINDINGS

During the last three decades, substantial evidence suggests that mitochondrial abnormality is a major contributor to placental dysfunction. In addition, mitochondrial damage caused by circulating bioactive factors released from the placenta may cause endothelial dysfunction and subsequent elevation in maternal blood pressure. In this review, we summarize the current knowledge of mitochondrial abnormality in the pathogenesis of preeclampsia and discuss therapeutic approaches targeting mitochondria for treatment of preeclampsia.

Computational Models on Pathological Redox Signalling Driven by Pregnancy: A Review

Oxidative stress is associated with a myriad of diseases including pregnancy pathologies with long-term cardiovascular repercussions for both the mother and baby. Aberrant redox signalling coupled with deficient antioxidant defence leads to chronic molecular impairment. Abnormal placentation has been considered the primary source for reactive species; however, placental dysfunction has been deemed secondary to maternal cardiovascular maladaptation in pregnancy. While various therapeutic interventions, aimed at combating deregulated oxidative stress during pregnancy have shown promise in experimental models, they often result as inconclusive or detrimental in clinical trials, warranting the need for further research to identify candidates. The strengths and limitations of current experimental methods in redox research are discussed. Assessment of redox status and oxidative stress in experimental models and in clinical practice remains challenging; the state-of-the-art of computational models in this field is presented in this review, comparing static and dynamic models which provide functional information such as protein-protein interactions, as well as the impact of changes in molecular species on the redox-status of the system, respectively. Enhanced knowledge of redox biology in during pregnancy through computational modelling such as generation of Systems Biology Markup Language model which integrates existing models to a larger network in the context of placenta physiology.

Prenatal Hypoxia Affects Foetal Cardiovascular Regulatory Mechanisms in a Sex- and Circadian-Dependent Manner: A Review

Prenatal hypoxia during the prenatal period can interfere with the developmental trajectory and lead to developing hypertension in adulthood. Prenatal hypoxia is often associated with intrauterine growth restriction that interferes with metabolism and can lead to multilevel changes. Therefore, we analysed the effects of prenatal hypoxia predominantly not associated with intrauterine growth restriction using publications up to September 2021. We focused on: (1) The response of cardiovascular regulatory mechanisms, such as the chemoreflex, adenosine, nitric oxide, and angiotensin II on prenatal hypoxia. (2) The role of the placenta in causing and attenuating the effects of hypoxia. (3) Environmental conditions and the mother's health contribution to the development of prenatal hypoxia. (4) The sex-dependent effects of prenatal hypoxia on cardiovascular regulatory mechanisms and the connection between hypoxia-inducible factors and circadian variability. We identified that the possible relationship between the effects of prenatal hypoxia on the cardiovascular regulatory mechanism may vary depending on circadian variability and phase of the days. In summary, even short-term prenatal hypoxia significantly affects cardiovascular regulatory mechanisms and programs hypertension in adulthood, while prenatal programming effects are not only dependent on the critical period, and sensitivity can change within circadian oscillations.

Sex-Specific Effects of Prenatal Hypoxia on the Cardiac Endothelin System in Adult Offspring

Fetal hypoxia, a major consequence of complicated pregnancies, impairs offspring cardiac tolerance to ischemia/reperfusion (I/R) insult, however, the mechanisms remain unknown. Endothelin-1 (ET-1) signaling through the endothelin A receptors (ET_A) is associated with cardiac dysfunction. We hypothesized that prenatal hypoxia exacerbates cardiac susceptibility to I/R via increased ET-1 and ET_A levels, while ET_A inhibition ameliorates this. Pregnant Sprague-Dawley rats were exposed to normoxia (21% O₂) or hypoxia (11% O₂) on gestational days 15-21. Offspring were aged to 4 months, and hearts were aerobically perfused or subjected to ex vivo I/R, with or without pre-infusion with an ET_A antagonist (ABT-627). ET-1 levels were assessed with ELISA in aerobically perfused and post-I/R left ventricles (LV). ET_A and ET_B levels were assessed by Western blotting in non-perfused LV. As hypothesized, ABT-627 infusion tended to improve post-I/R recovery in hypoxic females (p=0.0528), however, surprisingly, ABT-627 prevented post-I/R recovery only in the hypoxic males (p<0.001). ET-1 levels were increased in post-I/R LV in both sexes regardless of the prenatal exposure (p<0.01). ET_A expression was similar among all groups, while ET_B (isoform C) levels were decreased in prenatally hypoxic females (p<0.05). In prenatally hypoxic males, ET_A signaling may be essential for tolerance to I/R, while in prenatally hypoxic females, ET_A may contribute to cardiac dysfunction. Our data illustrate that understanding the prenatal history has critical implications for treatment strategies in adult chronic diseases.

Noninvasive Biomarkers for Cardiovascular Dysfunction Programmed in Male Offspring of Adverse Pregnancy

[Figure: see text].

Chronic hypoxia alters cardiac mitochondrial complex protein expression and activity in fetal guinea pigs in a sex-selective manner

We hypothesize that intrauterine hypoxia (HPX) alters the mitochondrial phenotype in fetal hearts contributing to developmental programming. Pregnant guinea pigs were exposed to normoxia (NMX) or hypoxia (HPX, 10.5% O2), starting at early [25 days (25d), 39d duration] or late gestation (50d, 14d duration). Near-term (64d) male and female fetuses were delivered by hysterotomy from anesthetized sows, and body/organ weights were measured. Left ventricles of fetal hearts were excised and frozen for measurement of expression of complex (I-V) subunits, fusion (Mfn2/OPA1) and fission (DRP1/Fis1) proteins, and enzymatic rates of I and IV from isolated mitochondrial proteins. Chronic HPX decreased fetal body weight and increased relative placenta weight regardless of timing. Early-onset HPX increased I, III, and V subunit levels, increased complex I but decreased IV activities in males but not females (all P < 0.05). Late-onset HPX decreased (P < 0.05) I, III, and V levels in both sexes but increased I and decreased IV activities in males only. Both HPX conditions decreased cardiac mitochondrial DNA content in males only. Neither early- nor late-onset HPX had any effect on Mfn2 levels but increased OPA1 in both sexes. Both HPX treatments increased DRP1/Fis1 levels in males. In females, early-onset HPX increased DRP1 with no effect on Fis1, whereas late-onset HPX increased Fis1 with no effect on DRP1. We conclude that both early- and late-onset HPX disrupts the expression/activities of select complexes that could reduce respiratory efficiency and shifts dynamics toward fission in fetal hearts. Thus, intrauterine HPX disrupts the mitochondrial phenotype predominantly in male fetal hearts, potentially altering cardiac metabolism and predisposing the offspring to heart dysfunction.

Hypoxia and the integrated stress response promote pulmonary hypertension and preeclampsia: Implications in drug development

Chronic hypoxia is a common cause of pulmonary hypertension, preeclampsia, and intrauterine growth restriction (IUGR). The molecular mechanisms underlying these diseases are not completely understood. Chronic hypoxia may induce the generation of reactive oxygen species (ROS) in mitochondria, promote endoplasmic reticulum (ER) stress, and result in the integrated stress response (ISR) in the pulmonary artery and uteroplacental tissues. Numerous studies have implicated hypoxia-inducible factors (HIFs), oxidative stress, and ER stress/unfolded protein response (UPR) in the development of pulmonary hypertension, preeclampsia and IUGR. This review highlights the roles of HIFs, mitochondria-derived ROS and UPR, as well as their interplay, in the pathogenesis of pulmonary hypertension and preeclampsia, and their implications in drug development.

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.

Placental hypoxia: What have we learnt from small animal models?

Intrauterine hypoxia is a feature of pregnancy complications, both at high altitude and sea level. To understand the placental response to reduced oxygen availability, small animal models of maternal inhalation hypoxia (MIH) or reduced uterine perfusion pressure (RUPP) may be utilised. The aim of this review was to compare the findings of those studies to identify the role of oxygen availability in adapting placental structural and functional phenotypes in relation to fetal outcome. It also sought to explore the evidence for the involvement of particular genes and protein signalling pathways in the placenta in mediating hypoxia driven alterations. The data available demonstrate that both MIH and RUPP can induce placental hypoxia, which affects placental structure and vascularity, as well as glucose, amino acid, calcium and possibly lipid transport capacity. In addition, changes have been observed in HIF, VEGF, insulin/IGF2, AMPK, mTOR, PI3K and PPARγ signalling, which may be key in linking together observed phenotypes under conditions of placental hypoxia. Many different manipulations have been examined, with varied outcomes depending on the intensity, timing and duration of the insult. Some manipulations have detrimental effects on placental phenotype, viability and fetal growth, whereas in others, the placenta appears to adapt to uphold fetal growth despite the challenge of low oxygen. Together these data suggest a complex response of the placenta to reduced oxygen availability, which links to changes in fetal outcomes. However, further work is required to explore the role of fetal sex, altered maternal physiology and placental molecular mechanisms to fully understand placental responses to hypoxia and their relevance for pregnancy outcome.

Cardiac magnetic resonance imaging: insights into developmental programming and its consequences for aging

Cardiovascular diseases (CVD) are important consequences of adverse perinatal conditions such as fetal hypoxia and maternal malnutrition. Cardiac magnetic resonance imaging (CMR) can produce a wealth of physiological information related to the development of the heart. This review outlines the current state of CMR technologies and describes the physiological biomarkers that can be measured. These phenotypes include impaired ventricular and atrial function, maladaptive ventricular remodeling, and the proliferation of myocardial steatosis and fibrosis. The discussion outlines the applications of CMR to understanding the developmental pathways leading to impaired cardiac function. The use of CMR, both in animal models of developmental programming and in human studies, is described. Specific examples are given in a baboon model of intrauterine growth restriction (IUGR). CMR offers great potential as a tool for understanding the sequence of dysfunctional adaptations of developmental origin that can affect the human cardiovascular system.

Developmental programming of cardiovascular function: a translational perspective

The developmental origins of health and disease (DOHaD) is a concept linking pre- and early postnatal exposures to environmental influences with long-term health outcomes and susceptibility to disease. It has provided a new perspective on the etiology and evolution of chronic disease risk, and as such is a classic example of a paradigm shift. What first emerged as the 'fetal origins of disease', the evolution of the DOHaD conceptual framework is a storied one in which preclinical studies played an important role. With its potential clinical applications of DOHaD, there is increasing desire to leverage this growing body of preclinical work to improve health outcomes in populations all over the world. In this review, we provide a perspective on the values and limitations of preclinical research, and the challenges that impede its translation. The review focuses largely on the developmental programming of cardiovascular function and begins with a brief discussion on the emergence of the 'Barker hypothesis', and its subsequent evolution into the more-encompassing DOHaD framework. We then discuss some fundamental pathophysiological processes by which developmental programming may occur, and attempt to define these as 'instigator' and 'effector' mechanisms, according to their role in early adversity. We conclude with a brief discussion of some notable challenges that hinder the translation of this preclinical work.

Dynamic placenta-on-a-chip model for fetal risk assessment of nanoparticles intended to treat pregnancy-associated diseases

Pregnant women often have to take medication either for pregnancy-related diseases or for previously existing medical conditions. Current maternal medications pose fetal risks due to off target accumulation in the fetus. Nanoparticles, engineered particles in the nanometer scale, have been used for targeted drug delivery to the site of action without off-target effects. This has opened new avenues for treatment of pregnancy-associated diseases while minimizing risks on the fetus. It is therefore instrumental to study the potential transfer of nanoparticles from the mother to the fetus. Due to limitations of in vivo and ex vivo models, an in vitro model mimicking the in vivo situation is essential. Placenta-on-a-chip provides a microphysiological recapitulation of the human placenta. Here, we reviewed the fetal risks associated with current therapeutic approaches during pregnancy, analyzed the advantages and limitations of current models used for nanoparticle assessment, and highlighted the current need for using dynamic placenta-on-a-chip models for assessing the safety of novel nanoparticle-based therapies during pregnancy.

Hypoxia and Mitochondrial Dysfunction in Pregnancy Complications

Hypoxia is a common and severe stress to an organism's homeostatic mechanisms, and hypoxia during gestation is associated with significantly increased incidence of maternal complications of preeclampsia, adversely impacting on the fetal development and subsequent risk for cardiovascular and metabolic disease. Human and animal studies have revealed a causative role of increased uterine vascular resistance and placental hypoxia in preeclampsia and fetal/intrauterine growth restriction (FGR/IUGR) associated with gestational hypoxia. Gestational hypoxia has a major effect on mitochondria of uteroplacental cells to overproduce reactive oxygen species (ROS), leading to oxidative stress. Excess mitochondrial ROS in turn cause uteroplacental dysfunction by damaging cellular macromolecules, which underlies the pathogenesis of preeclampsia and FGR. In this article, we review the current understanding of hypoxia-induced mitochondrial ROS and their role in placental dysfunction and the pathogenesis of pregnancy complications. In addition, therapeutic approaches selectively targeting mitochondrial ROS in the placental cells are discussed.

Placental treatment improves cardiac tolerance to ischemia/reperfusion insult in adult male and female offspring exposed to prenatal hypoxia

Offspring born from complicated pregnancies are at greater risk of cardiovascular disease in adulthood. Prenatal hypoxia is a common pregnancy complication that results in placental oxidative stress and impairs fetal development. Adult offspring exposed to hypoxia during fetal life are more susceptible to develop cardiac dysfunction, and show decreased cardiac tolerance to an ischemia/reperfusion (I/R) insult. To improve offspring cardiac outcomes, we have assessed the use of a placenta-targeted intervention during hypoxic pregnancies, by encapsulating the mitochondrial antioxidant MitoQ into nanoparticles (nMitoQ). We hypothesized that maternal nMitoQ treatment during hypoxic pregnancies improves cardiac tolerance to I/R insult in adult male and female offspring. Pregnant Sprague-Dawley rats were exposed to normoxia (21 % O²) or hypoxia (11 % O²) from gestational day 15-20, after injection with 100 μL saline or nMitoQ (125 μM) on GD15 (n=6-8/group). Male and female offspring were aged to 4 months. Both male and female offspring from hypoxic pregnancies showed reduced cardiac tolerance to I/R (assessed ex vivo using the isolated working heart technique) which was ameliorated by nMitoQ treatment. To identify potential molecular mechanisms for the changes in cardiac tolerance to I/R, cardiac levels/phosphorylation of proteins important for intracellular Ca²⁺ cycling were assessed with Western blotting. In prenatally hypoxic male offspring, improved cardiac recovery from I/R by nMitoQ was accompanied by increased cardiac phospholamban and phosphatase 2Ce levels, and a trend to decreased Ca²⁺/calmodulin-dependent protein kinase IIδ phosphorylation. In contrast, in female offspring, nMitoQ treatment in hypoxic pregnancies increased phospholamban and protein kinase Cε phosphorylation. Maternal nMitoQ treatment improves cardiac tolerance to I/R insult in adult offspring and thus has the potential to improve the later-life trajectory of cardiovascular health of adult offspring born from pregnancies complicated by prenatal hypoxia.

Hypoxia-induced mitochondrial abnormalities in cells of the placenta

INTRODUCTION

Impaired utero-placental perfusion is a well-known feature of early preeclampsia and is associated with placental hypoxia and oxidative stress. Although aberrations at the level of the mitochondrion have been implicated in PE pathophysiology, whether or not hypoxia-induced mitochondrial abnormalities contribute to placental oxidative stress is unknown.

METHODS

We explored whether abnormalities in mitochondrial metabolism contribute to hypoxia-induced placental oxidative stress by using both healthy term placentae as well as a trophoblast cell line (BeWo cells) exposed to hypoxia. Furthermore, we explored the therapeutic potential of the antioxidants MitoQ and quercetin in preventing hypoxia-induced placental oxidative stress.

RESULTS

Both in placental explants as well as BeWo cells, hypoxia resulted in reductions in mitochondrial content, decreased abundance of key molecules involved in the electron transport chain and increased expression and activity of glycolytic enzymes. Furthermore, expression levels of key regulators of mitochondrial biogenesis were decreased while the abundance of constituents of the mitophagy, autophagy and mitochondrial fission machinery was increased in response to hypoxia. In addition, placental hypoxia was associated with increased oxidative stress, inflammation, and apoptosis. Moreover, experiments with MitoQ revealed that hypoxia-induced reactive oxygen species originated from the mitochondria in the trophoblasts.

DISCUSSION

This study is the first to demonstrate that placental hypoxia is associated with mitochondrial-generated reactive oxygen species and significant alterations in the molecular pathways controlling mitochondrial content and function. Furthermore, our data indicate that targeting mitochondrial oxidative stress may have therapeutic benefit in the management of pathologies related to placental hypoxia.

Nanoparticle-encapsulated antioxidant improves placental mitochondrial function in a sexually dimorphic manner in a rat model of prenatal hypoxia

Pregnancy complications associated with prenatal hypoxia lead to increased placental oxidative stress. Previous studies suggest that prenatal hypoxia can reduce mitochondrial respiratory capacity and mitochondrial fusion, which could lead to placental dysfunction and impaired fetal development. We developed a placenta-targeted treatment strategy using a mitochondrial antioxidant, MitoQ, encapsulated into nanoparticles (nMitoQ) to reduce placental oxidative stress and (indirectly) improve fetal outcomes. We hypothesized that, in a rat model of prenatal hypoxia, nMitoQ improves placental mitochondrial function and promotes mitochondrial fusion in both male and female placentae. Pregnant rats were treated with saline or nMitoQ on gestational day (GD) 15 and exposed to normoxia (21% O₂ ) or hypoxia (11% O₂ ) from GD15-21. On GD21, male and female placental labyrinth zones were collected for mitochondrial respirometry assessments, mitochondrial content, and markers of mitochondrial biogenesis, fusion and fission. Prenatal hypoxia reduced complex IV activity and fusion in male placentae, while nMitoQ improved complex IV activity in hypoxic male placentae. In female placentae, prenatal hypoxia decreased respiration through the S-pathway (complex II) and increased N-pathway (complex I) respiration, while nMitoQ increased fusion in hypoxic female placentae. No changes in mitochondrial content, biogenesis or fission were found. In conclusion, nMitoQ improved placental mitochondrial function in male and female placentae from fetuses exposed to prenatal hypoxia, which may contribute to improved placental function. However, the mechanisms (ie, changes in mitochondrial respiratory capacity and mitochondrial fusion) were distinct between the sexes. Treatment strategies targeted against placental oxidative stress could improve placental mitochondrial function in complicated pregnancies.

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.

Mitochondria-Targeted Antioxidants: A Step towards Disease Treatment

Mitochondria are the main organelles that produce adenosine 5′-triphosphate (ATP) and reactive oxygen species (ROS) in eukaryotic cells and meanwhile susceptible to oxidative damage. The irreversible oxidative damage in mitochondria has been implicated in various human diseases. Increasing evidence indicates the therapeutic potential of mitochondria-targeted antioxidants (MTAs) for oxidative damage-associated diseases. In this article, we introduce the advantageous properties of MTAs compared with the conventional (nontargeted) ones, review different mitochondria-targeted delivery systems and antioxidants, and summarize their experimental results for various disease treatments in different animal models and clinical trials. The combined evidence demonstrates that mitochondrial redox homeostasis is a potential target for disease treatment. Meanwhile, the limitations and prospects for exploiting MTAs are discussed, which might pave ways for further trial design and drug development.

Riding the tiger - physiological and pathological effects of superoxide and hydrogen peroxide generated in the mitochondrial matrix

Elevated mitochondrial matrix superoxide and/or hydrogen peroxide concentrations drive a wide range of physiological responses and pathologies. Concentrations of superoxide and hydrogen peroxide in the mitochondrial matrix are set mainly by rates of production, the activities of superoxide dismutase-2 (SOD2) and peroxiredoxin-3 (PRDX3), and by diffusion of hydrogen peroxide to the cytosol. These considerations can be used to generate criteria for assessing whether changes in matrix superoxide or hydrogen peroxide are both necessary and sufficient to drive redox signaling and pathology: is a phenotype affected by suppressing superoxide and hydrogen peroxide production; by manipulating the levels of SOD2, PRDX3 or mitochondria-targeted catalase; and by adding mitochondria-targeted SOD/catalase mimetics or mitochondria-targeted antioxidants? Is the pathology associated with variants in SOD2 and PRDX3 genes? Filtering the large literature on mitochondrial redox signaling using these criteria highlights considerable evidence that mitochondrial superoxide and hydrogen peroxide drive physiological responses involved in cellular stress management, including apoptosis, autophagy, propagation of endoplasmic reticulum stress, cellular senescence, HIF1α signaling, and immune responses. They also affect cell proliferation, migration, differentiation, and the cell cycle. Filtering the huge literature on pathologies highlights strong experimental evidence that 30-40 pathologies may be driven by mitochondrial matrix superoxide or hydrogen peroxide. These can be grouped into overlapping and interacting categories: metabolic, cardiovascular, inflammatory, and neurological diseases; cancer; ischemia/reperfusion injury; aging and its diseases; external insults, and genetic diseases. Understanding the involvement of mitochondrial matrix superoxide and hydrogen peroxide concentrations in these diseases can facilitate the rational development of appropriate therapies.

The challenge of using nanotherapy during pregnancy: Technological aspects and biomedical implications

During the period of pregnancy, several processes and physiological adaptations occur in the body and metabolism of pregnant woman. These physiological adaptations in pregnant woman end up leading to a suppression in immune system favoring obstetric complications to the mother, fetus and placental tissue. An effective pharmacological therapy for these complications is still a challenge, since some drugs during pregnancy can have deleterious and teratogenic effects. An emerging alternative to pharmacological therapy during pregnancy is drugs encapsulated in nanoparticles (NP), recent area called nano-obstetrics. NP have the advantage of drug targeting and reduction of side effects. Then, maternal, placental or fetal uptake can be expected, depending on the characteristics of NP. Inorganic NP, crossing placental barrier effectively, but have several nanotoxicological effects. While organic NP appear to have a better targeting capacity and have few toxicological effects, but the studies are still scarce. Thus, in this review, were examined questions related to use and impact of physicochemical aspects of inorganic and organic NP during pregnancy.

Placenta-targeted treatment in hypoxic dams improves maturation and growth of fetal cardiomyocytes in vitro via the release of placental factors

NEW FINDINGS

What is the central question of this study? Does treatment of hypoxic dams with a placenta-targeted antioxidant prevent the release of placenta-derived factors that impair maturation or growth of fetal cardiomyocytes in vitro? What is the main finding and its importance? Factors released from hypoxic placentae impaired fetal cardiomyocyte maturation (induced terminal differentiation) and growth (increased cell size) in vitro, which was prevented by maternal treatment with a placenta-targeted antioxidant (nMitoQ). Moreover, there were no sex differences in the effects of placental factors on fetal cardiomyocyte maturation and growth. Overall, our data suggest that treatment targeted against placental oxidative stress could prevent fetal programming of cardiac diseases via the release of placental factors.

ABSTRACT

Pregnancy complications associated with placental oxidative stress may impair fetal organ development through the release of placenta-derived factors into the fetal circulation. We assessed the effect of factors secreted from placentae previously exposed to prenatal hypoxia on fetal cardiomyocyte development and developed a treatment strategy that targets placental oxidative stress by encapsulating the antioxidant MitoQ into nanoparticles (nMitoQ). We used a rat model of prenatal hypoxia (gestational day (GD) 15-21), which was treated with saline or nMitoQ on GD15. On GD21, placentae were harvested, placed in culture, and conditioned medium (containing placenta-derived factors) was collected after 24 h. This conditioned medium was then added to cultured cardiomyocytes from control dam fetuses. Conditioned medium from prenatally hypoxic placentae increased the percentage of binucleated cardiomyocytes (marker of terminal differentiation) and the size of mononucleated and binucleated cardiomyocytes (sign of hypertrophy), effects that were prevented by nMitoQ treatment. Our data suggest that factors derived from placentae previously exposed to prenatal hypoxia lead to abnormal fetal cardiomyocyte development, and show that treatment against placental oxidative stress may prevent fetal programming of cardiac disease.

Translatable mitochondria-targeted protection against programmed cardiovascular dysfunction

The prenatal origins of heart disease in offspring have been established. However, research in species with developmental milestones comparable to humans is lacking, preventing translation of this knowledge to clinical contexts. Using sheep and chickens, two species with similar cardiovascular developmental milestones to humans, we combined in vivo experiments with in vitro studies at organ, cellular, mitochondrial, and molecular levels. We tested mitochondria-targeted antioxidant intervention with MitoQ against cardiovascular dysfunction programmed by developmental hypoxia, a common complication in human pregnancy. Experiments in sheep determined in vivo fetal and adult cardiovascular function through surgical techniques not possible in humans, while those in chicken embryos isolated effects independent of maternal or placental influences. We show that hypoxia generates mitochondria-derived oxidative stress during cardiovascular development, programming endothelial dysfunction and hypertension in adult offspring. MitoQ treatment during hypoxic development protects against this cardiovascular risk via enhanced nitric oxide signaling, offering a plausible intervention strategy.

Prenatal Hypoxia and Placental Oxidative Stress: Insights from Animal Models to Clinical Evidences

Hypoxia is a common form of intrauterine stress characterized by exposure to low oxygen concentrations. Gestational hypoxia is associated with the generation of reactive oxygen species. Increase in oxidative stress is responsible for damage to proteins, lipids and DNA with consequent impairment of normal cellular functions. The purpose of this review is to propose a summary of preclinical and clinical evidences designed to outline the correlation between fetal hypoxia and oxidative stress. The results of the studies described show that increases of oxidative stress in the placenta is responsible for changes in fetal development. Specifically, oxidative stress plays a key role in vascular, cardiac and neurological disease and reproductive function dysfunctions. Moreover, the different finding suggests that the prenatal hypoxia-induced oxidative stress is associated with pregnancy complications, responsible for changes in fetal programming. In this way, fetal hypoxia predisposes the offspring to congenital anomalies and chronic diseases in future life. Several antioxidant agents, such as melatonin, erythropoietin, vitamin C, resveratrol and hydrogen, shown potential protective effects in prenatal hypoxia. However, future investigations will be needed to allow the implementation of these antioxidants in clinical practice for the promotion of health in early intrauterine life, in fetuses and children.

Placenta-targeted treatment strategies: An opportunity to impact fetal development and improve offspring health later in life

The Developmental Origins of Health and Disease (DOHaD) theory states that a sub-optimal prenatal and early postnatal environment during development leads to an increased risk of long-term development of adult chronic diseases. Developmental programming of disease has the potential to greatly impact the health of our population. Therefore, research has focused on the development of primary treatment strategies and/or therapeutic interventions for individuals who are at increased risk, with the objective to reverse or prevent later life onset of chronic disease in the offspring born from complicated pregnancies. Many studies have focused on systemic treatments and/or interventions in complicated pregnancies to improve offspring outcomes. However, there are limitations to systemic maternal/prenatal treatments, as most of the treatments are able to cross the placenta and have potential adverse off-target effects on the developing fetus. The placenta serves as the primary interface between mother and fetus, and placental dysfunction in complicated pregnancies has been associated with impaired fetal development and negative impact on offspring health. Therefore, recent research has focused on treatment strategies that specifically target the placenta to improve placental function and prevent passage of prenatal therapeutics and/or treatments into the fetal circulation, thus avoiding any potential adverse off-target effects on the fetus. This article reviews the currently available knowledge on treatment strategies and/or therapeutics that specifically target the placenta with the goal of improving pregnancy outcomes with a focus on long-term health of the offspring born of complicated pregnancies.

Strategies to target bioactive molecules to subcellular compartments. Focus on natural compounds

Many potential pharmacological targets are present in multiple subcellular compartments and have different pathophysiological roles depending on location. In these cases, selective targeting of a drug to the relevant subcellular domain(s) may help to sharpen its impact by providing topological specificity, thus limiting side effects, and to concentrate the compound where needed, thus increasing its effectiveness. We review here the state of the art in precision subcellular delivery. The major approaches confer "homing" properties to the active principle via permanent or reversible (in pro-drug fashion) modifications, or through the use of special-design nanoparticles or liposomes to ferry a drug(s) cargo to its desired destination. An assortment of peptides, substituents with delocalized positive charges, custom-blended lipid mixtures, pH- or enzyme-sensitive groups provide the main tools of the trade. Mitochondria, lysosomes and the cell membrane may be mentioned as the fronts on which the most significant advances have been made. Most of the examples presented here have to do with targeting natural compounds - in particular polyphenols, known as pleiotropic agents - to one or the other subcellular compartment.

Sex-Specific Effects of Nanoparticle-Encapsulated MitoQ (nMitoQ) Delivery to the Placenta in a Rat Model of Fetal Hypoxia

Pregnancy complications associated with chronic fetal hypoxia have been linked to the development of adult cardiovascular disease in the offspring. Prenatal hypoxia has been shown to increase placental oxidative stress and impair placental function in a sex-specific manner, thereby affecting fetal development. As oxidative stress is central to placental dysfunction, we developed a placenta-targeted treatment strategy using the antioxidant MitoQ encapsulated into nanoparticles (nMitoQ) to reduce placental oxidative/nitrosative stress and improve placental function without direct drug exposure to the fetus in order to avoid off-target effects during development. We hypothesized that, in a rat model of prenatal hypoxia, nMitoQ prevents hypoxia-induced placental oxidative/nitrosative stress, promotes angiogenesis, improves placental morphology, and ultimately improves fetal oxygenation. Additionally, we assessed whether there were sex differences in the effectiveness of nMitoQ treatment. Pregnant rats were intravenously injected with saline or nMitoQ (100 μl of 125 μM) on gestational day (GD) 15 and exposed to either normoxia (21% O2) or hypoxia (11% O2) from GD15 to 21. On GD21, placentae from both sexes were collected for detection of superoxide, nitrotyrosine, nitric oxide, CD31 (endothelial cell marker), and fetal blood spaces, Vegfa and Igf2 mRNA expression in the placental labyrinth zone. Prenatal hypoxia decreased male fetal weight, which was not changed by nMitoQ treatment; however, placental efficiency (fetal/placental weight ratio) decreased by hypoxia and was increased by nMitoQ in both males and females. nMitoQ treatment reduced the prenatal hypoxia-induced increase in placental superoxide levels in both male and female placentae but improved oxygenation in only female placentae. Nitrotyrosine levels were increased in hypoxic female placentae and were reduced by nMitoQ. Prenatal hypoxia reduced placental Vegfa and Igf2 expression in both sexes, while nMitoQ increased Vegfa and Igf2 expression only in hypoxic female placentae. In summary, our study suggests that nMitoQ treatment could be pursued as a potential preventative strategy against placental oxidative stress and programming of adult cardiovascular disease in offspring exposed to hypoxia in utero. However, sex differences need to be taken into account when developing therapeutic strategies to improve fetal development in complicated pregnancies, as nMitoQ treatment was more effective in placentae from females than males.

Placental Origins of Preeclampsia: Potential Therapeutic Targets

Preeclampsia (PE) remains a leading cause of maternal and perinatal morbidity and mortality in obstetrics worldwide. No effective treatments to reduce its incidence and severity in clinical practice are currently available. A variety of hypotheses have been generated aiming to explain the origins of PE, notably being the genetic predispositions and placental dysfunction. As regard to placental dysfunction, much progress has been made in basic research and several potential therapeutic targets have been identified. This review will discuss in detail the potential therapeutic targets in PE models including uteroplacental blood flow, oxidative stress, vasoactive factors and inflammation/immune response, and introduce the evolving technologies for placental research nowadays.

Intervention against hypertension in the next generation programmed by developmental hypoxia

Evidence derived from human clinical studies and experimental animal models shows a causal relationship between adverse pregnancy and increased cardiovascular disease in the adult offspring. However, translational studies isolating mechanisms to design intervention are lacking. Sheep and humans share similar precocial developmental milestones in cardiovascular anatomy and physiology. We tested the hypothesis in sheep that maternal treatment with antioxidants protects against fetal growth restriction and programmed hypertension in adulthood in gestation complicated by chronic fetal hypoxia, the most common adverse consequence in human pregnancy. Using bespoke isobaric chambers, chronically catheterized sheep carrying singletons underwent normoxia or hypoxia (10% oxygen [O2]) ± vitamin C treatment (maternal 200 mg.kg-1 IV daily) for the last third of gestation. In one cohort, the maternal arterial blood gas status, the value at which 50% of the maternal hemoglobin is saturated with oxygen (P50), nitric oxide (NO) bioavailability, oxidative stress, and antioxidant capacity were determined. In another, naturally delivered offspring were raised under normoxia until early adulthood (9 months). Lambs were chronically instrumented and cardiovascular function tested in vivo. Following euthanasia, femoral arterial segments were isolated and endothelial function determined by wire myography. Hypoxic pregnancy induced fetal growth restriction and fetal oxidative stress. At adulthood, it programmed hypertension by enhancing vasoconstrictor reactivity and impairing NO-independent endothelial function. Maternal vitamin C in hypoxic pregnancy improved transplacental oxygenation and enhanced fetal antioxidant capacity while increasing NO bioavailability, offsetting constrictor hyper-reactivity and replenishing endothelial function in the adult offspring. These discoveries provide novel insight into mechanisms and interventions against fetal growth restriction and adult-onset programmed hypertension in an animal model of complicated pregnancy in a species of similar temporal developmental milestones to humans.

Programming of Vascular Dysfunction in the Intrauterine Milieu of Diabetic Pregnancies

With the rising global tide of obesity, gestational diabetes mellitus (GDM) burgeoned into one of the most common antenatal disorders worldwide. Macrosomic babies born to diabetic mothers are more likely to develop risk factors for cardiovascular disease (CVD) before they reach adulthood. Rodent studies in offspring born to hyperglycemic pregnancies show vascular dysfunction characterized by impaired nitric oxide (NO)-mediated vasodilation and increased production of contractile prostanoids by cyclooxygenase 2 (COX-2). Vascular dysfunction is a key pathogenic event in the progression of diabetes-related vascular disease, primarily attributable to glucotoxicity. Therefore, glucose-induced vascular injury may stem directly from the hyperglycemic intrauterine environment of GDM pregnancy, as evinced by studies showing endothelial activation and inflammation at birth or in childhood in offspring born to GDM mothers. This review discusses potential mechanisms by which intrauterine hyperglycemia programs dysfunction in the developing vasculature.

Developmental origins of myocardial abnormalities in postnatal life 1

Poor quality and quantity maternal nutrition during pregnancy exerts permanent and damaging effects on the heart of the developing fetus. The developmental origin of adult heart disease is considered an important and critical factor in the pathogenesis of myocardial abnormalities in later life. Low birth mass, a marker of intrauterine stress, has been linked to a predisposition to heart disease. In this article, our work on the impact of exposure to a low-protein diet, in utero, on the developing heart and its long-term consequences are discussed. Other studies providing some supportive evidence are also described. It is proposed that normal fetal nutrition, growth, and development through efficient maternal nutrition (as well as other predisposing factors) before and during pregnancy may serve as a strategy for the primary prevention of heart disease.