Maternal uterine vascular remodeling during pregnancy

Perivascular Adipose Tissue and Uterine Artery Adaptations to Pregnancy

Pregnancy is characterized by longitudinal maternal, physiological adaptations to support the development of a fetus. One of the cardinal maternal adaptations during a healthy pregnancy is a progressive increase in uterine artery blood flow. This facilitates sufficient blood supply for the development of the placenta and the growing fetus. Regional hemodynamic changes in the uterine circulation, such as a vast reduction in uterine artery resistance, are mainly facilitated by changes in uterine artery reactivity and myogenic tone along with remodeling of the uterine arteries. These regional changes in vascular reactivity have been attributed to pregnancy-induced adaptations of cell-to-cell communication mechanisms, with an emphasis on the interaction between endothelial and vascular smooth muscle cells. Perivascular adipose tissue (PVAT) is considered the fourth layer of the vascular wall and contributes to the regulation of vascular reactivity in most vascular beds and most species. This review focuses on mechanisms of uterine artery reactivity and the role of PVAT in pregnancy-induced maternal vascular adaptations, with an emphasis on the uterine circulation.

Doppler Flow Indices and Prediction of Embryo Transfer Success and Pregnancy Outcome in Uterus Transplant Recipients

OBJECTIVE

 Doppler velocimetry of the uterine and umbilical arteries is used to predict preeclampsia and monitor fetal outcomes. There have been no reports of Doppler velocimetry indices in pregnancies conceived after uterus transplantation, which differ from traditional pregnancies because of different uterine vascular inflow and outflow and exposure to immunosuppressive agents. We sought to examine whether Doppler indices can be used to predict embryo transfer success after uterus transplantation and whether Doppler indices across pregnancy predict fetal growth restriction.

STUDY DESIGN

 This was a single-center cohort observational study of 14 uterus transplant recipients who underwent embryo transfer. Of these, 12 women successfully delivered 14 babies. Five Doppler investigations were performed within the cohort: (1) prepregnancy; (2) uterine artery assessment across pregnancy; (3) umbilical artery assessment across pregnancy; (4) successive pregnancies; and (5) fetal growth.

RESULTS

 Prepregnancy uterine artery Doppler indices did not correlate with successful implantation after embryo transfer. Uterine artery Doppler indices in uterus transplant recipients decreased across pregnancy as described in pregnancies without uterus transplantation. The umbilical artery systolic/diastolic velocity ratio was lower at all weeks of gestation after uterus transplantation compared with values described in pregnancies without uterus transplantation. In those women who delivered two successive babies after uterus transplant, umbilical artery Doppler indices were significantly lower during the second pregnancy. There was always forward flow throughout diastole in the umbilical arteries, and no babies experienced fetal growth restriction.

CONCLUSION

 In our study, uterus transplantation was not associated with abnormal blood flow indices in either the uterine or umbilical arteries. Although Doppler indices were not predictive of embryo transfer success, they supported the expectation that pregnancies after uterus transplantation at our center result in normally grown babies.

KEY POINTS

· Uterus transplantation is not associated with abnormal blood flow indices.. · Prepregnancy uterine artery Doppler indices did not correlate with successful embryo implantation.. · Doppler assessment supports the expectation of normal placentation, fetal growth, and healthy live births after uterus transplantation..

Gustatory and olfactory shifts during pregnancy and the postpartum period: A systematic review and meta-analysis

Pregnancy is a transformative phase marked by significant behavioral and physiological changes. Substantial changes in pregnancy-related hormones are thought to induce changes in chemosensory perception, as often observed in non-human animals. However, empirical behavioral research on pregnancy-related olfactory or gustatory changes has not yet reached a consensus. This PROSPERO pre-registered systematic review and meta-analysis evaluated published data of olfactory and gustatory changes in pregnant individuals, across the three pregnancy trimesters and postpartum period. Our comprehensive search strategy identified 20 relevant studies, for inclusion in the meta-analysis. The meta-analysis revealed that pregnant individuals, regardless of trimester, performed significantly poorer in terms of odour identification, however, no difference was detected between non-pregnant controls and women postpartum. Additionally, pregnant women in the second and third trimester rated olfactory stimuli to be more intense. A slight decline in odour pleasantness ratings was observed amongst those in the second trimester. No major difference was observed between pregnant and non-pregnant subjects in terms of gustatory functions, except the first trimester appeared to be associated with increased pleasantness for the sweet taste. Post-hoc meta-regression analyses revealed that pregnancy stage was a significant predictor for observed effect size for odour intensity ratings, but not for odour identification scores. These findings provide valuable insights into the interplay between pregnancy and chemosensory perception, highlighting systematic physiological changes due to pregnancy. Healthcare providers can also utilize the knowledge of sensory shifts to better support pregnant women in making appropriate dietary choices, managing sense-related discomfort, and leading to potential sensory interventions. Overall, this research enhances our comprehension of sensory shifts during pregnancy, benefiting maternal health and pregnancy-related care.

The effect of maternal position on placental blood flow and fetoplacental oxygenation in late gestation fetal growth restriction: a magnetic resonance imaging study

Fetal growth restriction (FGR) and maternal supine going-to-sleep position are both risk factors for late stillbirth. This study aimed to use magnetic resonance imaging (MRI) to quantify the effect of maternal supine position on maternal-placental and fetoplacental blood flow, placental oxygen transfer and fetal oxygenation in FGR and healthy pregnancies. Twelve women with FGR and 27 women with healthy pregnancies at 34-38 weeks' gestation underwent MRI in both left lateral and supine positions. Phase-contrast MRI and a functional MRI technique (DECIDE) were used to measure blood flow in the maternal internal iliac arteries (IIAs) and umbilical vein (UV), placental oxygen transfer (placental flux), fetal oxygen saturation (FO2 ), and fetal oxygen delivery (delivery flux). The presence of FGR, compared to healthy pregnancies, was associated with a 7.8% lower FO2 (P = 0.02), reduced placental flux, and reduced delivery flux. Maternal supine positioning caused a 3.8% reduction in FO2 (P = 0.001), and significant reductions in total IIA flow, placental flux, UV flow and delivery flux compared to maternal left lateral position. The effect of maternal supine position on fetal oxygen delivery was independent of FGR pregnancy, meaning that supine positioning has an additive effect of reducing fetal oxygenation further in women with FGR, compared to women with appropriately grown for age pregnancies. Meanwhile, the effect of maternal supine positioning on placental oxygen transfer was not independent of the effect of FGR. Therefore, growth-restricted fetuses, which are chronically hypoxaemic, experience a relatively greater decline in oxygen transfer when mothers lie supine in late gestation compared to appropriately growing fetuses. KEY POINTS: Fetal growth restriction (FGR) is the most common risk factor associated with stillbirth, and early recognition and timely delivery is vital to reduce this risk. Maternal supine going-to-sleep position is found to increase the risk of late stillbirth but when combined with having a FGR pregnancy, maternal supine position leads to 15 times greater odds of stillbirth compared to supine sleeping with appropriately grown for age (AGA) pregnancies. Using MRI, this study quantifies the chronic hypoxaemia experienced by growth-restricted fetuses due to 13.5% lower placental oxygen transfer and 26% lower fetal oxygen delivery compared to AGA fetuses. With maternal supine positioning, there is a 23% reduction in maternal-placental blood flow and a further 14% reduction in fetal oxygen delivery for both FGR and AGA pregnancies, but this effect is proportionally greater for growth-restricted fetuses. This knowledge emphasises the importance of avoiding supine positioning in late pregnancy, particularly for vulnerable FGR pregnancies.

Defective Uterine Spiral Artery Remodeling and Placental Senescence in a Pregnant Rat Model of Polycystic Ovary Syndrome

Pregnancy-related problems have been linked to impairments in maternal uterine spiral artery (SpA) remodeling. The mechanisms underlying this association are still unclear. It is also unclear whether hyperandrogenism and insulin resistance, the two common manifestations of polycystic ovary syndrome, affect uterine SpA remodeling. We verified previous work in which exposure to 5-dihydrotestosterone (DHT) and insulin (INS) in rats during pregnancy resulted in hyperandrogenism, insulin intolerance, and higher fetal mortality. Exposure to DHT and INS dysregulated the expression of angiogenesis-related genes in the uterus and placenta and also decreased expression of endothelial nitric oxide synthase and matrix metallopeptidases 2 and 9, increased fibrotic collagen deposits in the uterus, and reduced expression of marker genes for SpA-associated trophoblast giant cells. These changes were related to a greater proportion of unremodeled uterine SpAs and a smaller proportion of highly remodeled arteries in DHT + INS-exposed rats. Placentas from DHT + INS-exposed rats exhibited decreased basal and labyrinth zone regions, reduced maternal blood spaces, diminished labyrinth vascularity, and an imbalance in the abundance of vascular and smooth muscle proteins. Furthermore, placentas from DHT + INS-exposed rats showed expression of placental insufficiency markers and a significant increase in cell senescence-associated protein levels. Altogether, this work demonstrates that increased pregnancy complications in polycystic ovary syndrome may be mediated by problems with uterine SpA remodeling, placental functionality, and placental senescence.

Remodeling of the uterine artery during and early after pregnancy in the mouse

Pregnancy associates with dramatic changes in maternal cardiovascular physiology that ensure that the utero-placental circulation can support the developing fetus. Particularly striking is the marked flow-induced remodeling of uterine arteries during pregnancy and their recovery following birth. Whereas details are available in the literature on alterations in hemodynamics within and changes in the dimensions of uterine arteries during and following pregnancy in mice, we report here the first biaxial biomechanical phenotyping of these arteries during this dynamic period of growth and remodeling (G&R). To gain additional insight into the measured G&R, we also use a computational constrained mixture model to describe and predict findings, including simulations related to complications that may arise during pregnancy. It is found that dramatic pregnancy-induced remodeling of the uterine artery is largely, but not completely, reversed in the postpartum period, which appears to be driven by increases in collagen turnover among other intramural changes. By contrast, data on the remodeling of the ascending aorta, an elastic artery, reveal modest changes that are fully recovered postpartum. There is strong motivation to continue biomechanical studies on this critical aspect of women's health, which has heretofore not received appropriate consideration from the biomechanics community.

Mapping Pregnancy-dependent Sulfhydrome Unfolds Diverse Functions of Protein Sulfhydration in Human Uterine Artery

Uterine artery (UA) hydrogen sulfide (H2S) production is augmented in pregnancy and, on stimulation by systemic/local vasodilators, contributes to pregnancy-dependent uterine vasodilation; however, how H2S exploits this role is largely unknown. S-sulfhydration converts free thiols to persulfides at reactive cysteine(s) on targeted proteins to affect the entire proteome posttranslationally, representing the main route for H2S to elicit its function. Here, we used Tag-Switch to quantify changes in sulfhydrated (SSH-) proteins (ie, sulfhydrome) in H2S-treated nonpregnant and pregnant human UA. We further used the low-pH quantitative thiol reactivity profiling platform by which paired sulfhydromes were subjected to liquid chromatography tandem mass spectrometry-based peptide sequencing to generate site (cysteine)-specific pregnancy-dependent H2S-responsive human UA sulfhydrome. Total levels of sulfhydrated proteins were significantly greater in pregnant vs nonpregnant human UA and further stimulated by treatment with sodium hydrosulfide. We identified a total of 360 and 1671 SSH-peptides from 480 and 1186 SSH-proteins in untreated and sodium hydrosulfide-treated human UA, respectively. Bioinformatics analyses identified pregnancy-dependent H2S-responsive human UA SSH peptides/proteins, which were categorized to various molecular functions, pathways, and biological processes, especially vascular smooth muscle contraction/relaxation. Pregnancy-dependent changes in these proteins were rectified by immunoblotting of the Tag-Switch labeled SSH proteins. Low-pH quantitative thiol reactivity profiling failed to identify low abundance SSH proteins such as KATP channels in human UA; however, immunoblotting of Tag-Switch-labeled SSH proteins identified pregnancy-dependent upregulation of SSH-KATP channels without altering their total proteins. Thus, comprehensive analyses of human UA sulfhydromes influenced by endogenous and exogenous H2S inform novel roles of protein sulfhydration in uterine hemodynamics regulation.

Building a Scaffold for Arteriovenous Fistula Maturation: Unravelling the Role of the Extracellular Matrix

Vascular access is the lifeline for patients receiving haemodialysis as kidney replacement therapy. As a surgically created arteriovenous fistula (AVF) provides a high-flow conduit suitable for cannulation, it remains the vascular access of choice. In order to use an AVF successfully, the luminal diameter and the vessel wall of the venous outflow tract have to increase. This process is referred to as AVF maturation. AVF non-maturation is an important limitation of AVFs that contributes to their poor primary patency rates. To date, there is no clear overview of the overall role of the extracellular matrix (ECM) in AVF maturation. The ECM is essential for vascular functioning, as it provides structural and mechanical strength and communicates with vascular cells to regulate their differentiation and proliferation. Thus, the ECM is involved in multiple processes that regulate AVF maturation, and it is essential to study its anatomy and vascular response to AVF surgery to define therapeutic targets to improve AVF maturation. In this review, we discuss the composition of both the arterial and venous ECM and its incorporation in the three vessel layers: the tunica intima, media, and adventitia. Furthermore, we examine the effect of chronic kidney failure on the vasculature, the timing of ECM remodelling post-AVF surgery, and current ECM interventions to improve AVF maturation. Lastly, the suitability of ECM interventions as a therapeutic target for AVF maturation will be discussed.

The effects of progesterone on immune cellular function at the maternal-fetal interface and in maternal circulation

Progesterone is a sex steroid hormone that plays a critical role in the establishment and maintenance of pregnancy. This hormone drives numerous maternal physiological adaptations to ensure the continuation of pregnancy and to facilitate fetal growth, including broad and potent modulation of the maternal immune system to promote maternal-fetal tolerance. In this brief review, we provide an overview of the immunomodulatory functions of progesterone in the decidua, placenta, myometrium, and maternal circulation during pregnancy. Specifically, we summarize current evidence of the regulated functions of innate and adaptive immune cells induced by progesterone and its downstream effector molecules in these compartments, including observations in human pregnancy and in animal models. Our review highlights the gaps in knowledge of interactions between progesterone and maternal cellular immunity that may direct future research.

Single inhalation exposure to polyamide micro and nanoplastic particles impairs vascular dilation without generating pulmonary inflammation in virgin female Sprague Dawley rats

BACKGROUND

Exposure to micro- and nanoplastic particles (MNPs) in humans is being identified in both the indoor and outdoor environment. Detection of these materials in the air has made inhalation exposure to MNPs a major cause for concern. One type of plastic polymer found in indoor and outdoor settings is polyamide, often referred to as nylon. Inhalation of combustion-derived, metallic, and carbonaceous aerosols generate pulmonary inflammation, cardiovascular dysfunction, and systemic inflammation. Additionally, due to the additives present in plastics, MNPs may act as endocrine disruptors. Currently there is limited knowledge on potential health effects caused by polyamide or general MNP inhalation.

OBJECTIVE

The purpose of this study is to assess the toxicological consequences of a single inhalation exposure of female rats to polyamide MNP during estrus by means of aerosolization of MNP.

METHODS

Bulk polyamide powder (i.e., nylon) served as a representative MNP. Polyamide aerosolization was characterized using particle sizers, cascade impactors, and aerosol samplers. Multiple-Path Particle Dosimetry (MPPD) modeling was used to evaluate pulmonary deposition of MNPs. Pulmonary inflammation was assessed by bronchoalveolar lavage (BAL) cell content and H&E-stained tissue sections. Mean arterial pressure (MAP), wire myography of the aorta and uterine artery, and pressure myography of the radial artery was used to assess cardiovascular function. Systemic inflammation and endocrine disruption were quantified by measurement of proinflammatory cytokines and reproductive hormones.

RESULTS

Our aerosolization exposure platform was found to generate particles within the micro- and nano-size ranges (thereby constituting MNPs). Inhaled particles were predicted to deposit in all regions of the lung; no overt pulmonary inflammation was observed. Conversely, increased blood pressure and impaired dilation in the uterine vasculature was noted while aortic vascular reactivity was unaffected. Inhalation of MNPs resulted in systemic inflammation as measured by increased plasma levels of IL-6. Decreased levels of 17β-estradiol were also observed suggesting that MNPs have endocrine disrupting activity.

CONCLUSIONS

These data demonstrate aerosolization of MNPs in our inhalation exposure platform. Inhaled MNP aerosols were found to alter inflammatory, cardiovascular, and endocrine activity. These novel findings will contribute to a better understanding of inhaled plastic particle toxicity.

A placenta-on-a-chip model to determine the regulation of FKBPL and galectin-3 in preeclampsia

Preeclampsia is a pregnancy-specific cardiovascular disorder, involving significant maternal endothelial dysfunction. Although inappropriate placentation due to aberrant angiogenesis, inflammation and shallow trophoblast invasion are the root causes of preeclampsia, pathogenic mechanisms are poorly understood, particularly in early pregnancy. Here, we first confirm the abnormal expression of important vascular and inflammatory proteins, FK506-binding protein-like (FKBPL) and galectin-3 (Gal-3), in human plasma and placental tissues from women with preeclampsia and normotensive controls. We then employ a three-dimensional microfluidic placental model incorporating human umbilical vein endothelial cells (HUVECs) and a first trimester trophoblast cell line (ACH-3P) to investigate FKBPL and Gal-3 signaling in inflammatory conditions. In human samples, both circulating (n = 17 controls; n = 30 preeclampsia) and placental (n ≥ 6) FKBPL and Gal-3 levels were increased in preeclampsia compared to controls (plasma: FKBPL, p < 0.0001; Gal-3, p < 0.01; placenta: FKBPL, p < 0.05; Gal-3, p < 0.01), indicative of vascular dysfunction in preeclampsia. In our placenta-on-a-chip model, we show that endothelial cells are critical for trophoblast-mediated migration and that trophoblasts effectively remodel endothelial vascular networks. Inflammatory cytokine tumour necrosis factor-α (10 ng/mL) modulates both FKBPL and Gal-3 signaling in conjunction with trophoblast migration and impairs vascular network formation (p < 0.005). Our placenta-on-a-chip recapitulates aspects of inappropriate placental development and vascular dysfunction in preeclampsia.

Vascular Distribution and Expression Patterns of Angiogenic Factors in Caruncle during the Early Stage of Pregnancy in Goats (Capra hircus)

The placenta is a temporary maternal−fetal organ, and its maternal placenta (caruncle) is essential for fetal growth and development. The exchange function of the placenta requires vascular development (angiogenesis). However, the angiogenesis of the caruncle is poorly understood in goats during the early stage of pregnancy. Here, we investigated the vascular distribution, mRNA expression of major angiogenic factors, and the methylation levels of ANGPT2 in the goat caruncle. It showed that CAD (capillary area density), CSD (capillary surface density), and APC (area per capillary) increased gradually, while CND (capillary number density) showed an insignificant change, probably due to the variability between animals. The proportion of proliferating cells was observed to be very high (>26%) and increased (p < 0.002) approximately 2-fold from day 20 to 60 of pregnancy. Furthermore, the expression patterns of major angiogenic factors changed during the early stage of pregnancy. Interestingly, we discovered an absolute correlation between the mRNA for ANGPT2, TEK, FGF2, and vascular distribution. Subsequently, we evaluated the DNA methylation of ANGPT2, where we found that mean methylation was negatively correlated with CAD. The methylation at the CpG sites, such as CpG 4/18, CpG 9.10.11, and CpG 15, showed significant changes during the early stage of pregnancy. Thus, our findings suggest that the methylation of ANGPT2 may be involved in the regulation of caruncle angiogenesis during the early stage of pregnancy.

Evaluating cell viability, capillary perfusion, and collateral tortuosity in an ex vivo mouse intestine fluidics model

Numerous disease conditions involve the sudden or progressive loss of blood flow. Perfusion restoration is vital for returning affected organs to full health. While a range of clinical interventions can successfully restore flow to downstream tissues, the microvascular responses after a loss-of-flow event can vary over time and may involve substantial microvessel instability. Increased insight into perfusion-mediated capillary stability and access-to-flow is therefore essential for advancing therapeutic reperfusion strategies and improving patient outcomes. To that end, we developed a tissue-based microvascular fluidics model to better understand (i) microvascular stability and access-to-flow over an acute time course post-ischemia, and (ii) collateral flow in vessels neighboring an occlusion site. We utilized murine intestinal tissue regions by catheterizing a feeder artery and introducing perfusate at physiologically comparable flow-rates. The cannulated vessel as well as a portion of the downstream vessels and associated intestinal tissue were cultured while constant perfusion conditions were maintained. An occlusion was introduced in a selected arterial segment, and changes in perfusion within areas receiving varying degrees of collateral flow were observed over time. To observe the microvascular response to perfusion changes, we incorporated (i) tissues harboring cell-reporter constructs, specifically Ng2-DsRed labeling of intestinal pericytes, and (ii) different types of fluorescent perfusates to quantify capillary access-to-flow at discrete time points. In our model, we found that perfusion tracers could enter capillaries within regions downstream of an occlusion upon the initial introduction of perfusion, but at 24 h tissue perfusion was severely decreased. However, live/dead cell discrimination revealed that the tissue overall did not experience significant cell death, including that of microvascular pericytes, even after 48 h. Our findings suggest that altered flow conditions may rapidly initiate cellular responses that reduce capillary access-to-flow, even in the absence of cellular deterioration or hypoxia. Overall, this ex vivo tissue-based microfluidics model may serve as a platform upon which a variety of follow-on studies may be conducted. It will thus enhance our understanding of microvessel stability and access-to-flow during an occlusive event and the role of collateral flow during normal and disrupted perfusion.

Why is human uterine artery blood flow during pregnancy so high?

In healthy near-term women, blood flow to the uteroplacental circulation is estimated as 841 mL/min, which is greater than in other mammalian species. We argue that as uterine venous Po2 sets the upper limit for O2 diffusion to the fetus, high uterine artery blood flow serves to narrow the maternal arterial-to-uterine venous Po2 gradient and thereby raise uterine vein Po2. In support, we show that the reported levels for uterine artery blood flow agree with what is required to maintain normal fetal growth. Although residence at high altitudes (>2,500 m) depresses fetal growth, not all populations are equally affected; Tibetans and Andeans have higher levels of uterine artery blood flow than newcomers and exhibit normal fetal growth. Estimates of uterine venous Po2 from the umbilical blood-gas data available from healthy Andean pregnancies indicate that their high levels of uterine artery blood flow are consistent with their reported, normal birth weights. Unknown, however, are the effects on placental gas exchange of the lower levels of uterine artery blood flow seen in high-altitude newcomers or hypoxia-associated pregnancy complications. We speculate that, by widening the maternal artery to uterine vein Po2 gradient, lower levels of uterine artery blood flow prompt metabolic changes that slow fetal growth to match O2 supply.

The role of angiotensin II and relaxin in vascular adaptation to pregnancy

In brief

There is a pregnancy-induced vasodilation of blood vessels, which is known to have a protective effect on cardiovascular function and can be maintained postpartum. This review outlines the cardiovascular changes that occur in a healthy human and rodent pregnancy, as well as different pathways that are activated by angiotensin II and relaxin that result in blood vessel dilation.

Abstract

During pregnancy, systemic and uteroplacental blood flow increase to ensure an adequate blood supply that carries oxygen and nutrients from the mother to the fetus. This results in changes to the function of the maternal cardiovascular system. There is also a pregnancy-induced vasodilation of blood vessels, which is known to have a protective effect on cardiovascular health/function. Additionally, there is evidence that the effects of maternal vascular vasodilation are maintained post-partum, which may reduce the risk of developing high blood pressure in the next pregnancy and reduce cardiovascular risk later in life. At both non-pregnant and pregnant stages, vascular endothelial cells produce a number of vasodilators and vasoconstrictors, which transduce signals to the contractile vascular smooth muscle cells to control the dilation and constriction of blood vessels. These vascular cells are also targets of other vasoactive factors, including angiotensin II (Ang II) and relaxin. The binding of Ang II to its receptors activates different pathways to regulate the blood vessel vasoconstriction/vasodilation, and relaxin can interact with some of these pathways to induce vasodilation. Based on the available literature, this review outlines the cardiovascular changes that occur in a healthy human pregnancy, supplemented by studies in rodents. A specific focus is placed on vasodilation of blood vessels during pregnancy; the role of endothelial cells and endothelium-derived vasodilators will also be discussed. Additionally, different pathways that are activated by Ang II and relaxin that result in blood vessel dilation will also be reviewed.

Potassium Channels in the Uterine Vasculature: Role in Healthy and Complicated Pregnancies

A progressive increase in maternal uterine and placental blood flow must occur during pregnancy to sustain the development of the fetus. Changes in maternal vasculature enable an increased uterine blood flow, placental nutrient and oxygen exchange, and subsequent fetal development. K⁺ channels are important modulators of vascular function, promoting vasodilation, inducing cell proliferation, and regulating cell signaling. Different types of K⁺ channels, such as Ca²⁺-activated, ATP-sensitive, and voltage-gated, have been implicated in the adaptation of maternal vasculature during pregnancy. Conversely, K⁺ channel dysfunction has been associated with vascular-related complications of pregnancy, including intrauterine growth restriction and pre-eclampsia. In this article, we provide an updated and comprehensive literature review that highlights the relevance of K⁺ channels as regulators of uterine vascular reactivity and their potential as therapeutic targets.

The role of extravillous trophoblasts and uterine NK cells in vascular remodeling during pregnancy

Successful embryo implantation requires both a receptive endometrium and competent blastocysts. After implantation, the maternal decidua undergoes a series of changes, including uterine spiral artery (SA) remodeling to accommodate the fetus and provide nutrients and oxygen for the fetus to survive. Uterine spiral arteries transform from small-diameter, high-resistance arteries to large-diameter and low-resistance arteries during pregnancy. This transformation includes many changes, such as increased permeability and dilation of vessels, phenotypic switching and migration of vascular smooth muscle cells (VSMCs), transient loss of endothelial cells (ECs), endovascular invasion of extravillous trophoblasts (EVTs), and presence of intramural EVT, which are regulated by uterine NK (uNK) cells and EVTs. In this review, we mainly focus on the separate and combined roles of uNK cells and EVTs in uterine SA remodeling in establishing and maintaining pregnancy. New insight into related mechanisms will help us better understand the pathogenesis of pregnancy complications such as recurrent pregnancy loss (RPL) and preeclampsia (PE).

The Effect of Tauroursodeoxycholic Acid (TUDCA) Treatment on Pregnancy Outcomes and Vascular Function in a Rat Model of Advanced Maternal Age

Advanced maternal age (≥35 years) increases the risk of vascular complications in pregnancy that can result in fetal growth restriction and preeclampsia. Endoplasmic reticulum (ER) stress has been linked to adverse pregnancy outcomes in these complicated pregnancies. However, the role of ER stress in advanced maternal age is not known. We hypothesize that increased ER stress contributes to altered vascular function and poor pregnancy outcomes, and that treatment with the ER-stress inhibitor TUDCA will improve pregnancy outcomes. First, young and aged non-pregnant/pregnant rats were used to assess ER stress markers in mesenteric arteries; mesenteric artery phospho-eIF2α and CHOP expression were increased in aged dams compared to young dams. In a second study, young and aged control and TUDCA-treated dams were studied on gestational day (GD) 20 (term = 22 days). TUDCA treatment was provided via the drinking water throughout pregnancy (GD0-GD20; calculated dose of 150 mg/kg/day TUDCA). ER stress markers were quantified in mesenteric arteries, blood pressure was measured, pregnancy outcomes were recorded, mesenteric and main uterine arteries were isolated and vascular function was assessed by wire myography. Aged dams had increased phospho-eIF2α and CHOP expression, reduced fetal weight, reduced litter size, and impaired uterine artery relaxation. In the aged dams, TUDCA treatment reduced phospho-eIF2α and CHOP expression, reduced blood pressure, improved fetal body weight, and tended to improve uterine artery function compared to control-treated aged dams. In conclusion, our data illustrate the role of ER stress, as well as TUDCA as a potential therapeutic that may benefit pregnancy outcomes in advanced maternal age.

Using MRI to differentiate upper-lateral intracavitary pregnancy and interstitial pregnancy for the patients with pregnancies in the uterotubal junction during the first trimester

Objectives

To retrospectively evaluate the diagnostic value of MRI for the uterotubal junctional pregnancies during the first trimester.

Methods

This retrospective study involved 59 patients (January 2016 to July 2021) with a preoperative imaging diagnosis of uterotubal junctional pregnancy. Using operative and pathological reports as the reference standard, we identified 22 patients with upper-lateral intracavitary (angular) pregnancy and 37 patients with interstitial pregnancy. Two senior radiologists, blinded to the patients’ information, reviewed the MRI images and determined each MRI feature based on the original interpretation criteria. Any disagreement was resolved by discussion to achieve a consensus. The sensitivity and specificity of each MRI feature were calculated according to the reference standard.

Results

The endometrial thickness in the upper-lateral intracavitary pregnancy group was larger than in the interstitial group (p = 0.001). The cutoff value of the endometrial thickness was 11.5 mm with a sensitivity, specificity, and area under the curve that were 77.3%, 64.9%, and 0.743, respectively. Two key features to diagnose upper-lateral intracavitary pregnancy were “medial free edge” and “medial free edge plus above-cutoff endometrial thickness.” The sensitivity and specificity of the medial free edge were 100% and 94.9%, respectively. The sensitivity and specificity of the medial free edge plus above-cutoff endometrial thickness were 77.3% and 100%, respectively. The key feature to diagnose interstitial pregnancy was an “intact lateral junctional zone,” of which the sensitivity and specificity were 94.6% and 100%, respectively.

Conclusions

MRI can be used to differentiate the upper-lateral intracavitary pregnancy and interstitial pregnancy during the first trimester.

Key Points

• We demonstrated MRI diagnostic criteria for the interstitial pregnancy and upper-lateral intracavitary pregnancy.

• MRI might be used to identify the complex interstitial pregnancies, those with a gestational sac protruding into the uterine cavity.

Spatial transcriptomic profiles of mouse uterine microenvironments at pregnancy day 7.5†

Uterine dysfunctions lead to fertility disorders and pregnancy complications. Normal uterine functions at pregnancy depend on crosstalk among multiple cell types in uterine microenvironments. Here, we performed the spatial transcriptomics and single-cell RNA-seq assays to determine local gene expression profiles at the embryo implantation site of the mouse uterus on pregnancy day 7.5 (D7.5). The spatial transcriptomic annotation identified 11 domains of distinct gene signatures, including a mesometrial myometrium, an anti-mesometrial myometrium, a mesometrial decidua enriched with natural killer cells, a vascular sinus zone for maternal vessel remodeling, a fetal-maternal interface, a primary decidual zone, a transition decidual zone, a secondary decidual zone, undifferentiated stroma, uterine glands, and the embryo. The scRNA-Seq identified 12 types of cells in the D7.5 uterus including three types of stromal fibroblasts with differentiated and undifferentiated markers, one cluster of epithelium including luminal and glandular epithelium, mesothelium, endothelia, pericytes, myelomonocytic cell, natural killer cells, and lymphocyte B. These single-cell RNA signatures were then utilized to deconvolute the cell-type compositions of each individual uterine microenvironment. Functional annotation assays on spatial transcriptomic data revealed uterine microenvironments with distinguished metabolic preferences, immune responses, and various cellular behaviors that are regulated by region-specific endocrine and paracrine signals. Global interactome among regions is also projected based on the spatial transcriptomic data. This study provides high-resolution transcriptome profiles with locality information at the embryo implantation site to facilitate further investigations on molecular mechanisms for normal pregnancy progression.

Preeclampsia and Venous Thromboembolism: Pathophysiology and Potential Therapy

Preeclampsia (PET) is a multisystem inflammatory disorder that represents a leading cause of feto-maternal morbidity and mortality, complicating 2–5% of all pregnancies. PET incurs an increased risk of venous thromboembolism, which is one of the leading causes of death in pregnancy and in the postpartum period. This prothrombotic phenotype is attributable to the maternal phase of PET, which is characterized by a systemic inflammatory response and coagulation activation. Research continues to be undertaken in terms of preventative measures, however, currently revolves around pharmacological low dose aspirin initiated in the first trimester of pregnancy for those with risk factors. Treatment involves antenatal corticosteroids for fetal lung development in preterm birth, parenteral magnesium sulfate for fetal neuroprotection and maternal seizure prophylaxis, and timely birth of the fetus and placenta being the only definitive treatment of PET. Patients with a venous thromboembolism (VTE) risk deemed to be >1–3% are treated with pharmacological thromboprophylaxis in the form of low molecular weight heparin. Completing each woman’s VTE risk assessment is crucial, particularly in the setting of PET, as there is also a proven associated competing hemorrhagic risk.

A mathematical model of maternal vascular growth and remodeling and changes in maternal hemodynamics in uncomplicated pregnancy

The maternal vasculature undergoes tremendous growth and remodeling (G&R) that enables a > 15-fold increase in blood flow through the uterine vasculature from conception to term. Hemodynamic metrics (e.g., uterine artery pulsatility index, UA-PI) are useful for the prognosis of pregnancy complications; however, improved characterization of the maternal hemodynamics is necessary to improve prognosis. The goal of this paper is to develop a mathematical framework to characterize maternal vascular G&R and hemodynamics in uncomplicated human pregnancies. A validated 1D model of the human vascular tree from the literature was adapted and inlet blood flow waveforms at the ascending aorta at 4 week increments from 0 to 40 weeks of gestation were prescribed. Peripheral resistances of each terminal vessel were adjusted to achieve target flow rates and mean arterial pressure at each gestational age. Vessel growth was governed by wall shear stress (and axial lengthening in uterine vessels), and changes in vessel distensibility were related to vessel growth. Uterine artery velocity waveforms generated from this model closely resembled ultrasound results from the literature. The literature UA-PI values changed significantly across gestation, increasing in the first month of gestation, then dramatically decreasing from 4 to 20 weeks. Our results captured well the time-course of vessel geometry, material properties, and UA-PI. This 1D fluid-G&R model captured the salient hemodynamic features across a broad range of clinical reports and across gestation for uncomplicated human pregnancy. While results capture available data well, this study highlights significant gaps in available data required to better understand vascular remodeling in pregnancy.

Estrogen-Induced Uterine Vasodilation in Pregnancy and Preeclampsia

Normal pregnancy is associated with dramatically increased estrogen biosynthesis whose role is believed to raise uterine blood flow to facilitate the bi-directional maternal-fetal exchanges of gases (O₂ and CO₂), to deliver nutrients, and exhaust wastes to support fetal development and survival. Constrained uterine blood flow in pregnancy is a leading cause of preeclampsia with fetal growth restriction, rendering investigations of uterine hemodynamics to hold a high promise to inform pathways as targets for therapeutic interventions for preeclampsia. The mechanisms of estrogen-induced uterine vasodilation in pregnancy have long been attributed to enhanced endothelium production of nitric oxide, but clinical trials targeting this pathway that dominates uterine hemodynamics have achieved no to little success. Emerging evidence has recently shown a novel proangiogenic vasodilatory role of hydrogen sulfide in regulating uterine hemodynamics in pregnancy and preeclampsia, provoking a new field of perinatal research in searching for alternative pathways for pregnancy disorders especially preeclampsia and intrauterine growth restriction. This minireview is intended to summarize the nitric oxide pathway and to discuss the emerging hydrogen sulfide pathway in modulating estrogen-induced uterine vasodilation in pregnancy and preeclampsia.

How hypoxia slows fetal growth: insights from high altitude

A continuous oxygen supply is vital for fueling fetal growth, yet we know surprisingly little as to the precise mechanisms by which hypoxia reduces fetal growth. Animal models, while important, are limited by the enormous variability in mammalian physiologic responses to pregnancy. One of the earliest models for understanding hypoxia-induced reductions in fetal growth came from studies at high altitude that showed high altitude to have one of the strongest depressant effects on fetal growth. But all populations are not equally affected. Dolma et al., have added valuable information now showing that that Ladakhis, like Tibetans and Andeans, have a lower-than-expected frequency of small-for-gestational age (SGA) infants. Consistent with previous reports, these authors also found that uterine artery diameters at mid pregnancy (week 26–28) were larger in women giving birth to appropriate-for-gestational-age (AGA) than SGA infants at high but, interestingly, not at low altitude. Much remains to be learned about the physiologic pathways by which hypoxia impairs fetal growth. The variability among high-altitude populations and increasing sophistication of tools for investigating causal mechanisms have the potential to expand our presently limited means for identifying new treatments for hypoxia-related complications of pregnancy and fetal life.

From stem cells to spiral arteries: A journey through early placental development

Early placental development lays the foundation of a healthy pregnancy, and numerous tightly regulated processes must occur for the placenta to meet the increasing nutrient and oxygen exchange requirements of the growing fetus later in gestation. Inadequacies in early placental development can result in disorders such as fetal growth restriction that do not present clinically until the second half of gestation. Indeed, growth restricted placentae exhibit impaired placental development and function, including reduced overall placental size, decreased branching of villi and the blood vessels within them, altered trophoblast function, and impaired uterine vascular remodelling, which together combine to reduce placental exchange capacity. This review explores the importance of early placental development across multiple anatomical aspects of placentation, from the stem cells and lineage hierarchies from which villous core cells and trophoblasts arise, through extravillous trophoblast invasion and spiral artery remodelling, and finally remodelling of the larger uterine vessels.

Dual Role of Thrombospondin-1 in Flow-Induced Remodeling

(1) Background: Chronic increases in blood flow, as in cardiovascular diseases, induce outward arterial remodeling. Thrombospondin-1 (TSP-1) is known to interact with matrix proteins and immune cell-surface receptors, but its contribution to flow-mediated remodeling in the microcirculation remains unknown. (2) Methods: Mesenteric arteries were ligated in vivo to generate high- (HF) and normal-flow (NF) arteries in wild-type (WT) and TSP-1-deleted mice (TSP-1-/-). After 7 days, arteries were isolated and studied ex vivo. (3) Results: Chronic increases in blood flow induced outward remodeling in WT mice (increasing diameter from 221 ± 10 to 280 ± 10 µm with 75 mmHg intraluminal pressure) without significant effect in TSP-1-/- (296 ± 18 to 303 ± 14 µm), neutropenic or adoptive bone marrow transfer mice. Four days after ligature, pro inflammatory gene expression levels (CD68, Cox2, Gp91phox, p47phox and p22phox) increased in WT HF arteries but not in TSP-1-/- mice. Perivascular neutrophil accumulation at day 4 was significantly lower in TSP-1-/- than in WT mice. (4) Conclusions: TSP-1 origin is important; indeed, circulating TSP-1 participates in vasodilation, whereas both circulating and tissue TSP-1 are involved in arterial wall thickness and diameter expansion.

Fetal Cardiac Lipid Sensing Triggers an Early and Sex-related Metabolic Energy Switch in Intrauterine Growth Restriction

CONTEXT

Intrauterine growth restriction (IUGR) is an immediate outcome of an adverse womb environment, exposing newborns to developing cardiometabolic disorders later in life.

OBJECTIVE

This study investigates the cardiac metabolic consequences and underlying mechanism of energy expenditure in developing fetuses under conditions of IUGR.

METHODS

Using an animal model of IUGR characterized by uteroplacental vascular insufficiency, mitochondrial function, gene profiling, lipidomic analysis, and transcriptional assay were determined in fetal cardiac tissue and cardiomyocytes.

RESULTS

IUGR fetuses exhibited an upregulation of key genes associated with fatty acid breakdown and β-oxidation (Acadvl, Acadl, Acaa2), and mitochondrial carnitine shuttle (Cpt1a, Cpt2), instigating a metabolic gene reprogramming in the heart. Induction of Ech1, Acox1, Acox3, Acsl1, and Pex11a indicated a coordinated interplay with peroxisomal β-oxidation and biogenesis mainly observed in females, suggesting sexual dimorphism in peroxisomal activation. Concurring with the sex-related changes, mitochondrial respiration rates were stronger in IUGR female fetal cardiomyocytes, accounting for enhanced adenosine 5'-triphosphate production. Mitochondrial biogenesis was induced in fetal hearts with elevated expression of Ppargc1a transcript specifically in IUGR females. Lipidomic analysis identified the accumulation of arachidonic, eicosapentaenoic, and docosapentaenoic polyunsaturated long-chain fatty acids (LCFAs) in IUGR fetal hearts, which leads to nuclear receptor peroxisome proliferator-activated receptor α (PPARα) transcriptional activation in cardiomyocytes. Also, the enrichment of H3K27ac chromatin marks to PPARα-responsive metabolic genes in IUGR fetal hearts outlines an epigenetic control in the early metabolic energy switch.

CONCLUSION

This study describes a premature and sex-related remodeling of cardiac metabolism in response to an unfavorable intrauterine environment, with specific LCFAs that may serve as predictive effectors leading to IUGR.

Altered Vascular Adaptations to Pregnancy in a Rat Model of Advanced Maternal Age

Advanced maternal age (≥35 years old) increases the risk of pregnancy complications such as preeclampsia and fetal growth restriction. We previously demonstrated vascular dysfunction and abnormal pregnancy outcomes in a rat model of advanced maternal age. However, vascular adaptations to pregnancy in aging were not studied. We hypothesize that advanced maternal age is associated with a more vasoconstrictive phenotype due to reduced nitric oxide (NO) and increased activity of matrix metalloproteinases (MMPs), contributing to impaired vascular adaptations to pregnancy. A rat model of advanced maternal age was used: young (4 months) and aged (9.5 months; ∼35 years in humans) non-pregnant and pregnant rats. On gestational day 20 (term = 22 days; non-pregnant rats were aged-matched), blood pressure and heart rate were measured (tail cuff plethysmography) and vascular function was assessed in mesenteric arteries (wire myography). Endothelium-dependent relaxation to methylcholine (MCh) was assessed in the presence/absence of nitric oxide synthase inhibitor (L-NAME), or inhibitors of endothelium-dependent hyperpolarization (EDH; apamin and TRAM-34). Vasoconstriction responses to big endothelin-1 (bigET-1), in the presence/absence of MMPs-inhibitor (GM6001) or endothelin converting enzyme (ECE-1) inhibitor (CGS35066), in addition, ET-1 responsiveness, were measured. Blood pressure was elevated only in aged non-pregnant rats (p < 0.001) compared to all other groups. MCh responses were not different, however, L-NAME decreased maximum vasodilation in young (p < 0.01) and aged pregnant rats (p < 0.001), and decreased MCh sensitivity in young non-pregnant rats (p < 0.01), without effects in aged non-pregnant rats. EDH contribution to relaxation was similar in young non-pregnant, and aged non-pregnant and pregnant rats, while EDH-mediated relaxation was absent in young pregnant rats (p < 0.001). BigET-1 responses were enhanced in aged non-pregnant (p < 0.01) and pregnant rats (p < 0.05). No significant changes in bigET-1 conversion occurred in the presence of MMP-inhibitor, whereas ECE-1 inhibition reduced bigET-1 constriction in aged rats (p < 0.01). No differences in ET-1 sensitivity were observed. In conclusion, contrary to our hypothesis, reduced blood pressure, and an increased EDH-dependent contribution to vasodilation suggest a compensatory mechanism that may reflect beneficial adaptations in these aged rats that were able to maintain pregnancy. These data increase our understanding of how the vascular adaptive pathways in pregnancy compensate for advanced maternal age.

High Na+ Salt Diet and Remodeling of Vascular Smooth Muscle and Endothelial Cells

Our knowledge on essential hypertension is vast, and its treatment is well known. Not all hypertensives are salt-sensitive. The available evidence suggests that even normotensive individuals are at high cardiovascular risk and lower survival rate, as blood pressure eventually rises later in life with a high salt diet. In addition, little is known about high sodium (Na⁺) salt diet-sensitive hypertension. There is no doubt that direct and indirect Na⁺ transporters, such as the Na/Ca exchanger and the Na/H exchanger, and the Na/K pump could be implicated in the development of high salt-induced hypertension in humans. These mechanisms could be involved following the destruction of the cell membrane glycocalyx and changes in vascular endothelial and smooth muscle cells membranes’ permeability and osmolarity. Thus, it is vital to determine the membrane and intracellular mechanisms implicated in this type of hypertension and its treatment.

Gold nanoparticle biodistribution in pregnant mice following intravenous administration varies with gestational age

The use of nanoparticles (NPs) to deliver therapeutics to reproductive organs is an emerging approach to safely and effectively treat mothers and babies facing pregnancy complications. This study investigates the biodistribution of two different sized gold-based NPs in pregnant mice following systemic delivery as a function of gestational age. Poly(ethylene glycol)-coated 15 nm gold nanoparticles or 150 nm diameter silica core/gold nanoshells were intravenously administered to pregnant mice at gestational days (E)9.5 or 14.5. NP distribution was analyzed twenty-four hours later by inductively coupled plasma-mass spectrometry and silver staining of histological specimens. More NPs accumulated in placentas than embryos and delivery to these tissues was greater at E9.5 than E14.5. Neither NP type affected fetal weight or placental weight, indicating minimal short-term toxicity in early to mid-stage pregnancy. These findings warrant continued development of NPs as tools to deliver therapeutics to reproductive tissues safely.

Obesogenic diet exposure alters uterine natural killer cell biology and impairs vasculature remodeling in mice†

Prepregnancy obesity associates with adverse reproductive outcomes that impact maternal and fetal health. While obesity-driven mechanisms underlying adverse pregnancy outcomes remain unclear, local uterine immune cells are strong but poorly studied candidates. Uterine immune cells, particularly uterine natural killer cells (uNKs), play central roles in orchestrating developmental events in pregnancy. However, the effect of obesity on uNK biology is poorly understood. Using an obesogenic high-fat/high-sugar diet (HFD) mouse model, we set out to examine the effects of maternal obesity on uNK composition and establishment of the maternal-fetal interface. HFD exposure resulted in weight gain-dependent increases in systemic inflammation and rates of fetal resorption. While HFD did not affect total uNK frequencies, HFD exposure did lead to an increase in natural cytotoxicity receptor-1 expressing uNKs as well as overall uNK activity. Importantly, HFD-associated changes in uNK coincided with impairments in uterine artery remodeling in mid but not late pregnancy. Comparison of uNK mRNA transcripts from control and HFD mice identified HFD-directed changes in genes that play roles in promoting activity/cytotoxicity and vascular biology. Together, this work provides new insight into how obesity may impact uNK processes central to the establishment of the maternal-fetal interface in early and mid pregnancy. Moreover, these findings shed light on the cellular processes affected by maternal obesity that may relate to overall pregnancy health.

Uterine Vascular Control Preconception and During Pregnancy

Successful pregnancy and reproduction are dependent on adequate uterine blood flow, placental perfusion, and vascular responsivity to fetal demands. The ability to support pregnancy centers on systemic adaptation and endometrial preparation through decidualization, embryonic implantation, trophoblast invasion, arterial/arteriolar reactivity, and vascular remodeling. These adaptations occur through responsiveness to endocrine signaling and local uteroplacental mediators. The purpose of this article is to highlight the current knowledge associated with vascular remodeling and responsivity during uterine preparation for and during pregnancy. We focus on maternal cardiovascular systemic and uterine modifications, endometrial decidualization, implantation and invasion, uterine and spiral artery remodeling, local uterine regulatory mechanisms, placentation, and pathological consequences of vascular dysfunction during pregnancy. © 2021 American Physiological Society. Compr Physiol 11:1-23, 2021.

Long non-coding RNA MALAT1 regulates trophoblast functions through VEGF/VEGFR1 signaling pathway

Preeclampsia, as one of the most serious pregnancy-specific diseases, manifested by high blood pressure and companied by proteinuria in pregnancy women after 20 gestational weeks. Although the underlying mechanism has been studied for decades, no unambiguous interpretation of this phenomenon was well recognized. Recent researches focused on long non-coding RNAs (lncRNAs) as key regulators of cancer cell proliferation, invasion, migration and angiogenesis. Tumor development and placenta implantation share several common biological behaviors. The expression of lncRNA MALAT1 was downregulated in the placenta of patients with severe preeclampsia. MALAT1 smart silencer significantly inhibited HTR-8/SVneo trophoblast cell proliferation, invasion, migration and tube formation in vitro. Moreover, MALAT1 inhibited the expression of angiogenic factors in umbilical vein endothelial cells co-cultured with trophoblasts. These results indicated that MALAT1 was involved in the pathogenesis of preeclampsia and might be a candidate biomarker as well as a therapeutic target for preeclampsia.

Acetaminophen Attenuates invasion and alters the expression of extracellular matrix enzymes and vascular factors in human first trimester trophoblast cells

Acetaminophen is one of the most common medications taken during pregnancy, considered safe for maternal health and fetal development. However, recent epidemiological studies have associated prenatal acetaminophen use with several developmental disorders in offspring. As acetaminophen can freely cross into and through the placenta, epidemiological associations with prenatal acetaminophen use may reflect direct actions on the fetus and/or the impact of altered placental functions. In the absence of rigorous mechanistic studies, our understanding of how prenatal acetaminophen exposure can cause long-term effects in offspring is limited. The objective of this study was to determine whether acetaminophen can alter key functions of a major placental cell type by utilizing immortalized human first trimester trophoblast cells. This study employed a comparative analysis with the nonsteroidal, anti-inflammatory drug aspirin, which has established effects in first trimester trophoblast cells. We report that immortalized trophoblast cells express the target proteins of acetaminophen and aspirin: cyclooxygenase (COX) -1 and -2. Unlike aspirin, acetaminophen significantly repressed the expression of angiogenesis and vascular remodeling genes in HTR-8/SVneo cells. Moreover, acetaminophen impaired trophoblast invasion by over 80%, while aspirin had no effect on invasion. Acetaminophen exposure reduced the expression of matrix metalloproteinase (MMP)-2 and -9 and increased the expression of tissue inhibitors of matrix metalloproteinases 2, leading to an imbalance in the ratio of proteolytic enzymes. Finally, a bioinformatic approach identified novel acetaminophen-responsive gene networks associated with key trophoblast functions and disease. Together these results suggest that prenatal acetaminophen use may interfere with critical trophoblast functions early in gestation, which may subsequently impact fetal development.

Maternal and Neonatal Complications in Patients With Diminished Ovarian Reserve in In-Vitro Fertilization/Intracytoplasmic Sperm Injection Cycles

BACKGROUND

Diminished ovarian reserve (DOR) is one of the most intractable clinical issues in human reproduction and is reported to be associated with raised risk of recurrent pregnancy loss and aneuploid blastocysts. In this study, we aimed to explore whether DOR was also associated with maternal and neonatal complications in in-vitro fertilization/intracytoplasmic sperm injection cycles.

METHODS

A retrospective cohort study including women below 40 years of age who achieved singleton live birth after fresh embryo transfer in in-vitro fertilization/intracytoplasmic sperm injection cycles in a single center from January 2012 to June 2019 was conducted. Participants with DOR, defined as basal follicle-stimulating hormone (FSH) ≥ 10IU/L and antimullerian hormone (AMH) < 1.2ng/ml, were enrolled as the study group. The controls were 1:2 matched by age and body mass index with FSH < 10IU/L and AMH ≥ 1.2ng/ml. Maternal and neonatal complications were compared between the DOR group and the controls.

RESULTS

A total of 579 women, 193 in the DOR group and 386 matched as controls, were included in this study. Compared to controls, the incidence of hypertensive disorders of pregnancy was significantly increased in the DOR group (5.7% vs. 2.1%, P = 0.021). DOR patients also presented slightly higher incidences of preterm birth (10.9% vs. 7.5%, P = 0.174) and low birthweight (6.2% vs. 5.4%, P = 0.704) yet without statistical significances. The incidences of gestational diabetes mellitus and placenta previa were comparable between the two groups.

CONCLUSION

Compared to women with normal ovarian reserve, women with diminished ovarian reserve might have elevated incidence of hypertensive disorders of pregnancy. Patients with diminished ovarian reserve might need more strict antenatal care.

Current Researches, Rationale, Plausibility, and Evidence Gaps on Metformin for the Management of Hypertensive Disorders of Pregnancy

Hypertensive disorders of pregnancy (HDP) are a group of morbid pregnancy complications, with preeclampsia (PE) being the most common subclassification among them. PE affects 2%–8% of pregnancies globally and threatens maternal and fetal health seriously. However, the only effective treatment of PE to date is the timely termination of pregnancy, albeit with increased perinatal risks. Hence, more emerging therapies for PE management are in urgent need. Originally introduced as the first-line therapy for type 2 diabetes mellitus, metformin (MET) has now been found in clinical trials to significantly reduce the incidence of gestational hypertension and PE in pregnant women with PE-related risks, including but not limited to pregestational diabetes mellitus, gestational diabetes mellitus, polycystic ovary syndrome, or obesity. Additionally, existing clinical data have preliminarily ensured the safety of taking MET during human pregnancies. Relevant lab studies have indicated that the underlying mechanism includes angiogenesis promotion, endothelial protection, anti-inflammatory effects, and particularly protective effects on trophoblast cells against the risk factors, which are beneficial to placental development. Together with its global availability, easy administration, and low cost, MET is expected to be a promising option for the prevention and treatment of PE. Nevertheless, there are still some limitations in current studies, and the design of the relevant research scheme is supposed to be further improved in the future. Herein, we summarize the relevant clinical and experimental researches to discuss the rationale, safety, and feasibility of MET for the management of HDP. At the end of the article, gaps in current researches are proposed. Concretely, experimental MET concentration and PE models should be chosen cautiously. Besides, the clinical trial protocol should be further optimized to evaluate the reduction in the prevalence of PE as a primary endpoint. All of those evidence gaps may be of guiding significance to improve the design of relevant experiments and clinical trials in the future.

Recent Insights on the Maternal Microbiota: Impact on Pregnancy Outcomes

Hormonal changes during and after pregnancy are linked with modifications in the maternal microbiota. We describe the importance of the maternal microbiota in pregnancy and examine whether changes in maternal microbiotic composition at different body sites (gut, vagina, endometrium) are associated with pregnancy complications. We analyze the likely interactions between microbiota and the immune system. During pregnancy, the gastrointestinal (gut) microbiota undergoes profound changes that lead to an increase in lactic acid-producing bacteria and a reduction in butyrate-producing bacteria. The meaning of such changes needs clarification. Additionally, several studies have indicated a possible involvement of the maternal gut microbiota in autoimmune and lifelong diseases. The human vagina has its own microbiota, and changes in vaginal microbiota are related to several pregnancy-related complications. Recent studies show reduced lactobacilli, increased bacterial diversity, and low vaginal levels of beta-defensin 2 in women with preterm births. In contrast, early and healthy pregnancies are characterized by low diversity and low numbers of bacterial communities dominated by Lactobacillus. These observations suggest that early vaginal cultures that show an absence of Lactobacillus and polymicrobial vaginal colonization are risk factors for preterm birth. The endometrium is not a sterile site. Resident endometrial microbiota has only been defined recently. However, questions remain regarding the main components of the endometrial microbiota and their impact on the reproductive tract concerning both fertility and pregnancy outcomes. A classification based on endometrial bacterial patterns could help develop a microbiota-based diagnosis as well as personalized therapies for the prevention of obstetric complications and personalized treatments through nutritional, microbiotic, or pharmaceutical interventions.

The genomic regulatory elements for estrogen receptor alpha transactivation-function-1 regulated genes

Estrogen receptor alpha (ERα) is a ligand-dependent transcription regulator, containing two transactivation functional domains, AF-1 and AF-2. The selective estrogen receptor modulators (SERMs), including 4-hydroxytamoxifen (4OHT), activate AF-1 preferentially rather than AF-2. However, it is unclear whether this specific function is related to the tissue-selective functionality of SERMs. Moreover, there is no information determining AF-1-dependent estrogenic-genes existing in tissues. We sought to identify AF-1-dependent estrogenic-genes using the AF-2 mutated knock-in (KI) mouse model, AF2ERKI. AF2ER is an AF-2 disrupted estradiol (E2)-insensitive mutant ERα, but AF-1-dependent transcription can be activated by the estrogen-antagonists, fulvestrant (ICI) and 4OHT. Gene profiling and ChIP-Seq analysis identified Klk1b21 as an ICI-inducible gene in AF2ERKI uterus. The regulatory activity was analyzed further using a cell-based reporter assay. The 5'-flanking 0.4k bp region of Klk1b21 gene responded as an ERα AF-1-dependent estrogen-responsive promoter. The 150 bp minimum ERα binding element (EBE) consists of three direct repeats. These three half-site sequences were essential for the ERα-dependent transactivation and were differentially recognized by E2 and 4OHT for the gene activation. This response was impaired when the minimum EBE was fused with a thymidine-kinase promoter but could be restored by fusion with the 100 bp minimum transcription initiation element (TIE) of Klk1b21, suggesting that the cooperative function of EBE and TIE is essential for mediating AF-1-dependent transactivation. These findings provide the first in vivo evidence that endogenous ERα AF-1 dominant estrogenic-genes exist in estrogen-responsive organs. Such findings will aid in understanding the mechanism of ERα-dependent tissue-selective activity of SERMs.

Pregnancy-specific transcriptional changes upon endotoxin exposure in mice

Objectives Pregnant women are more susceptible to certain infections; however, this increased susceptibility is not fully understood. Herein, systems biology approaches were utilized to elucidate how pregnancy modulates tissue-specific host responses to a bacterial product, endotoxin. Methods Pregnant and non-pregnant mice were injected with endotoxin or saline on 16.5 days post coitum (n=8-11 per group). The uterus, cervix, liver, adrenal gland, kidney, lung, and brain were collected 12 h after injection and transcriptomes were measured using microarrays. Heatmaps and principal component analysis were used for visualization. Differentially expressed genes between groups were assessed using linear models that included interaction terms to determine whether the effect of infection differed with pregnancy status. Pathway analysis was conducted to interpret gene expression changes. Results We report herein a multi-organ atlas of the transcript perturbations in pregnant and non-pregnant mice in response to endotoxin. Pregnancy strongly modified the host responses to endotoxin in the uterus, cervix, and liver. In contrast, pregnancy had a milder effect on the host response to endotoxin in the adrenal gland, lung, and kidney. However, pregnancy did not drastically affect the host response to endotoxin in the brain. Conclusions Pregnancy imprints organ-specific host immune responses upon endotoxin exposure. These findings provide insight into the host-response against microbes during pregnancy.

Design of nanomaterials for applications in maternal/fetal medicine

Pregnancy complications are commonplace and the challenges of treatment during pregnancy with few options available pose a risk to the health of both the mother and baby. Patients suffering from conditions such as preeclampsia, placenta accreta, and intrauterine growth restriction have few treatment options apart from emergency caesarean section. Fortunately, researchers are beginning to develop nanomedicine-based therapies that could be utilized to treat conditions affecting the mother, placenta, or fetus to improve the prognosis for mothers and their unborn children. This review summarizes the field's current understanding of nanoparticle biodistribution and therapeutic effect following systemic or vaginal administration and overviews the design parameters researchers should consider when developing nanomedicines for maternal/fetal health. It also describes safety considerations for nanomedicines to limit undesirable maternal or fetal side effects and discusses future work that should be performed to advance nanomedicine for maternal/fetal health. With additional development and implementation, the application of nanomedicine to treat pregnancy complications may mitigate the need for emergency caesarean sections and allow pregnancies to extend to term.

Ovine uterine artery hydrogen sulfide biosynthesis in vivo: effects of ovarian cycle and pregnancy†

Uterine vasodilation dramatically increases during the follicular phase of the estrous cycle and pregnancy, which are estrogen-dominant physiological states. Uterine vasodilation is believed to be mainly controlled by local uterine artery (UA) production of vasodilators and angiogenic factors. The extremely potent vasodilator and proangiogenic hydrogen sulfide (H2S) is synthesized via metabolizing L-cysteine by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CTH). This study was designed to determine if UA H2S production increases with augmented expression and/or activity of CBS and/or CTH during the ovarian cycle and pregnancy in sheep. Uterine arteries from intact nonpregnant (NP) luteal and follicular phase and late (130-135 days, term ≈ 145 days) pregnant (P) ewes were collected; endothelium-enriched proteins (UAendo) and endothelium-denuded smooth muscle (UAvsm) were mechanically prepared for accessing CBS and CTH proteins by immunoblotting; their cellular localization was determined by semi-quantitative immunofluorescence microscopy. H2S production was measured by the methylene blue assay. Immunoblotting revealed that CBS but not CTH protein was greater in P > > > NP follicular > luteal UAendo and UAvsm (P < 0.001). H2S production was greater in P > > > NP UAendo and UAvsm (P < 0.01). Pregnancy-augmented UAendo and UAvsm H2S production was inhibited by the specific CBS but not CTH inhibitor. CBS and CTH proteins were localized to both endothelium and smooth muscle; however, only CBS protein was significantly greater in P vs NP UA endothelium and smooth muscle. Thus, ovine UA H2S production is significantly augmented via selectively upregulating endothelium and smooth muscle CBS during the follicular phase and pregnancy in vivo.

Circulating pregnancy hormone relaxin as a first trimester biomarker for preeclampsia

OBJECTIVE

Preeclampsia, a multi-system hypertensive disorder, is associated with perturbations in the maternal cardiovascular system during early pregnancy. The corpus luteal hormone relaxin, a potent vasodilator, may contribute to physiological circulatory changes especially in early gestation when circulating levels are highest. This study investigated whether first trimester circulating relaxin may be a suitable biomarker for the early prediction of preeclampsia.

METHODS

Relaxin was initially measured in first-trimester samples of women who developed late-onset preeclamptic (LO-PE; delivery ≥ 34 weeks; n = 33) and uncomplicated pregnancies (n = 25) in Pittsburgh, USA. Subsequently, to expand the group numbers, relaxin was measured in women who developed LO-PE (n = 95), early-onset preeclamptic (EO-PE; delivery < 34 weeks; n = 57), and uncomplicated pregnancies (n = 469) in Utrecht, the Netherlands.

RESULTS

In the Pittsburgh subjects, low relaxin levels (lowest centile: <p10) showed an adjusted odds ratio (OR) of 5.29 (95%CI 1.10-25.5) for LO-PE. In the Utrecht population, low relaxin levels (<p10) demonstrated adjusted ORs of 1.45 (95%CI 0.54-3.90) and 2.03 (95%CI 1.06-3.88) for EO-PE and LO-PE respectively, the latter increasing to an adjusted OR of 3.18 (95%CI 1.41-7.20) when newborn weight was < 10%. Serum relaxin concentrations slightly improved the detection rate of a previously derived prediction model for LO-PE from 42.5% to 45.1% at a fixed 10% false-positive rate.

CONCLUSION

Relaxin shows little improvement in the performance of first trimester prediction models, which does not support its clinical implementation as a biomarker. Although this study was only correlational, the results point to a possible pathophysiologic role for low relaxin levels in pregnancies that later develop LO-PE.

Hemodynamic forces enhance decidualization via endothelial-derived prostaglandin E2 and prostacyclin in a microfluidic model of the human endometrium

STUDY QUESTION

Does the uterine vasculature play a localized role in promoting stromal cell decidualization in the human endometrium?

SUMMARY ANSWER

Our study demonstrated that hemodynamic forces induced secretion of specific endothelial cell-derived prostanoids that enhanced endometrial perivascular decidualization via a paracrine mechanism.

WHAT IS KNOWN ALREADY

Differentiation of stromal cell fibroblasts into the specialized decidua of the placenta is a progesterone-dependent process; however, histologically, it has long been noted that the first morphological signs of decidualization appear in the perivascular stroma. These observations suggest that the human endometrial vasculature plays an active role in promoting stromal differentiation.

STUDY DESIGN, SIZE, DURATION

Primary human endometrial stromal cells were co-cultured for 14 days with primary uterine microvascular endothelial cells within a microfluidic Organ-on-Chip model of the endometrium.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cultures were maintained with estradiol and a progestin, with or without continuous laminar perfusion to mimic hemodynamic forces derived from the blood flow. Some cultures additionally received exogenous agonist-mediated challenges. Decidualization in the microfluidic model was assessed morphologically and biochemically. ELISA was used to examine the culture effluent for expression of decidualization markers and prostaglandins. Immunofluorescence was used to monitor cyclooxygenase-2 expression in association with decidualization.

MAIN RESULTS AND THE ROLE OF CHANCE

A significantly enhanced stromal decidualization response was observed in the co-cultures when the endothelial cells were stimulated with hemodynamic forces (e.g. laminar shear stress) derived from controlled microfluidic perfusion (<0.001). Furthermore, the enhanced progestin-driven stromal differentiation was mediated via cyclooxygenase-2 and the paracrine action of prostaglandin E2 and prostacyclin. Altogether, these translational findings indicate that the vascular endothelium plays a key physiologic role during the early events of perivascular decidualization in the human endometrium.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

This report is largely an in vitro study. Although we were able to experimentally mimic hemodynamic forces in our microfluidic model, we have not yet determined the contribution of additional cell types to the decidualization process or determined the precise physiological rates of shear stress that the microvasculature of the endometrium undergoes in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

Identification of specific endothelial-derived prostaglandins and their role during endometrial reproductive processes may have clinical utility as therapeutic targets for reproductive disorders such as infertility, endometriosis, adenomyosis, pre-eclampsia and poor pregnancy outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Veterans Affairs (I01 BX002853), the Bill and Melinda Gates Foundation Grand Challenges Exploration (OPP1159411), the Environmental Toxicology Training Grant (NIH T32 ES007028) and the Environmental Protection Agency STAR Center Grant (83573601).

CONFLICT OF INTEREST

The authors report no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Reduced right ventricular function on cardiovascular magnetic resonance imaging is associated with uteroplacental impairment in tetralogy of Fallot

BACKGROUND

Maternal right ventricular (RV) dysfunction (measured by echocardiography) is associated with impaired uteroplacental circulation, however echocardiography has important limitations in the assessment of RV function. We therefore aimed to investigate the association of pre-pregnancy RV and left ventricular (LV) function measured by cardiovascular magnetic resonance with uteroplacental Doppler flow parameters in pregnant women with repaired Tetralogy of Fallot (ToF).

METHODS

Women with repaired ToF were examined, who had been enrolled in a prospective multicenter study of pregnant women with congenital heart disease. Clinical data and CMR evaluation before pregnancy were compared with uteroplacental Doppler parameters at 20 and 32 weeks gestation. In particular, pulsatility index (PI) of uterine and umbilical artery were studied.

RESULTS

We studied 31 women; mean age 30 years, operated at early age. Univariable analyses showed that reduced RV ejection fraction (RVEF; P = 0.037 and P = 0.001), higher RV end-systolic volume (P = 0.004) and higher LV end-diastolic and end-systolic volume (P = 0.001 and P = 0.003, respectively) were associated with higher uterine or umbilical artery PI. With multivariable analyses (corrected for maternal age and body mass index), reduced RVEF before pregnancy remained associated with higher umbilical artery PI at 32 weeks (P = 0.002). RVEF was lower in women with high PI compared to women with normal PI during pregnancy (44% vs. 53%, p = 0.022). LV ejection fraction was not associated with uterine or umbilical artery PI.

CONCLUSIONS

Reduced RV function before pregnancy is associated with abnormal uteroplacental Doppler flow parameters. It could be postulated that reduced RV function on pre-pregnancy CMR (≤2 years) is a predisposing factor for impaired placental function in women with repaired ToF.

Bone Marrow Microvasculature

The skeleton is highly vascularized due to the various roles blood vessels play in the homeostasis of bone and marrow. For example, blood vessels provide nutrients, remove metabolic by-products, deliver systemic hormones, and circulate precursor cells to bone and marrow. In addition to these roles, bone blood vessels participate in a variety of other functions. This article provides an overview of the afferent, exchange and efferent vessels in bone and marrow and presents the morphological layout of these blood vessels regarding blood flow dynamics. In addition, this article discusses how bone blood vessels participate in bone development, maintenance, and repair. Further, mechanical loading-induced bone adaptation is presented regarding interstitial fluid flow and pressure, as regulated by the vascular system. The role of the sympathetic nervous system is discussed in relation to blood vessels and bone. Finally, vascular participation in bone accrual with intermittent parathyroid hormone administration, a medication prescribed to combat age-related bone loss, is described and age- and disease-related impairments in blood vessels are discussed in relation to bone and marrow dysfunction. © 2020 American Physiological Society. Compr Physiol 10:1009-1046, 2020.

Angiopoietin-2 regulated by progesterone induces uterine vascular remodeling during pregnancy

During pregnancy, the uterus undergoes intense neovascularization and vascular remodeling to supply oxygen and nutrients to the embryo. During this period, progesterone secreted from the ovary has effects on vascular remodeling in the endometrium and interacts with angiogenic factors. However, the exact mechanism of uterine vascular remodeling during pregnancy is poorly understood. Therefore, the aim of the present study was to investigate the association between angiopoietin-2 (Ang-2), one of the angiopoietins, and intrauterine vessel remodeling during pregnancy, and to determine the effect of progesterone on Ang-2 levels. Changes in Ang-2 expression were observed according to quantitative modification of progesterone using pregnant mice and human uterine microvascular endothelial cells. As a result, Ang-2 was observed mainly in the mesometrial region (MR) of the uterus during the period between implantation and placentation. Furthermore, a substantial amount of Ang-2 also appeared in endothelial cells, particularly of the venous sinus region (VSR). Interestingly, Ang-2 expression was increased by progesterone, whereas estrogen had limited effects. To confirm the association between Ang-2 and progesterone, the function of the progesterone receptor (PR) was inhibited using RU486, a blocker of PR. Ang-2 expression and vascular remodeling of the VSR in the uterus were decreased when the functions of progesterone were inhibited. Overall, the regulation of Ang-2 by progesterone/PR was associated with vascular remodeling in the VSR during pregnancy. The present study proposed a solution to prevent pregnancy failure due to a lack of vascularity in the uterus in advance.

Emerging concepts of shear stress in placental development and function

Blood flow, and the force it generates, is critical to placental development and function throughout pregnancy. This mechanical stimulation of cells by the friction generated from flow is called shear stress (SS) and is a fundamental determinant of vascular homeostasis, regulating remodelling and vasomotor tone. This review describes how SS is fundamental to the establishment and regulation of the blood flow through the uteroplacental and fetoplacental circulations. Amongst the most recent findings is that alongside the endothelium, embryonic stem cells and the villous trophoblast are mechanically sensitive. A complex balance of forces is required to enable effective establishment of the uteroplacental circulation, while protecting the embryo and placental villi. SS also generates flow-mediated vasodilatation through the release of endothelial nitric oxide, a process vital for adequate placental blood flow. The identification of SS sensors and the mechanisms governing how the force is converted into biochemical signals is a fast-paced area of research, with multiple cellular components under investigation. For example, the Piezo1 ion channel is mechanosensitive in a variety of tissues including the fetoplacental endothelium. Enhanced Piezo1 activity has been demonstrated in response to the Yoda1 agonist molecule, suggesting the possibility for developing tools to manipulate these channels. Whether such agents might progress to novel therapeutics to improve blood flow through the placenta requires further consideration and research.

Plasticity of the Maternal Vasculature During Pregnancy

Maternal cardiovascular changes during pregnancy include an expansion of plasma volume, increased cardiac output, decreased peripheral resistance, and increased uteroplacental blood flow. These adaptations facilitate the progressive increase in uteroplacental perfusion that is required for normal fetal growth and development, prevent the development of hypertension, and provide a reserve of blood in anticipation of the significant blood loss associated with parturition. Each woman's genotype and phenotype determine her ability to adapt in response to molecular signals that emanate from the fetoplacental unit. Here, we provide an overview of the major hemodynamic and cardiac changes and then consider regional changes in the splanchnic, renal, cerebral, and uterine circulations in terms of endothelial and vascular smooth muscle cell plasticity. Although consideration of gestational disease is beyond the scope of this review, aberrant signaling and/or maternal responsiveness contribute to the etiology of several common gestational diseases such as preeclampsia, intrauterine growth restriction, and gestational diabetes.

Excessive umbilical cord coiling confers risk of elevated nocturnal blood pressure and severe/early-onset preeclampsia

BACKGROUND

The associations between umbilical cord coiling, feto-placental vascular resistance and maternal blood pressure (BP) are not well understood.

METHOD

We retrospectively analyzed 502 pregnant women suspected of hypertensive disorders in the third trimester from a hospital-based cohort, who underwent ambulatory BP monitoring and umbilical artery Doppler velocimetry examinations within 14 days before delivery. By applying quantile regression, a significant quantile-dependent positive association between umbilical cord coiling index and umbilical artery pulsatility index (UAPIMOM; converted to multiples of median) was observed from above 0.75th quantiles for each parameter.

RESULTS

Using the cutoffs both at the 0.75th quantile to define high umbilical cord coiling (≥0.28 coils/cm) and high UAPIMOM (≥1.30), respectively, a graded increase in BP level was observed from patients with both low, either high and both high categories. Multivariate linear and quantile regression revealed that the high umbilical cord coiling/high UAPIMOM interaction was significantly correlated with night-time mean DBP level. Moreover, umbilical cord hypercoiling (≥0.3 coils/cm) was significantly correlated with night-time DBP with an average increase of ∼5 mmHg from the 0.05th to 0.70th quantiles and independently predicted the occurrence of severe (odds ratio 2.32, 95% confidence interval: 1.22-4.41) and early-onset (odds ratio 2.43, 95% confidence interval: 1.18-4.97) preeclampsia after adjusting for covariates. Further mediation analysis showed that elevated high UAPIMOM (≥1.30) could explain 11.4% of the umbilical cord hypercoiling → high night-time DBP association.

CONCLUSION

Therefore, this retrospective study identifies excessive umbilical cord coiling, and its interaction with increased feto-placental vascular resistance, as novel risk factors for nocturnal BP elevation and preeclampsia.