IL1ß-NFκß-Myocardin signaling axis governs trophoblast-directed plasticity of vascular smooth muscle cells.

Vascular smooth muscle cell (VSMC) plasticity is fundamental in uterine spiral artery remodeling during placentation in Eutherian mammals. Our previous work showed that the invasion of trophoblast cells into uterine myometrium coincides with a phenotypic change of VSMCs. Here, we elucidate the mechanism by which trophoblast cells confer VSMC plasticity. Analysis of genetic markers on E13.5, E16.5, and E19.5 in the rat metrial gland, the entry point of uterine arteries, revealed that trophoblast invasion is associated with downregulation of MYOCARDIN, α-smooth muscle actin, and calponin1, and concomitant upregulation of Smemb in VSMCs. Myocardin overexpression or knockdown in VSMCs led to upregulation or downregulation of contractile markers, respectively. Co-culture of trophoblast cells with VSMCs decreased MYOCARDIN expression along with compromised expression of contractile markers in VSMCs. However, co-culture of trophoblast cells with VSMCs overexpressing MYOCARDIN inhibited their change in phenotype, whereas, overexpression of transactivation domain deleted MYOCARDIN failed to elicit this response. Furthermore, the co-culture of trophoblast cells with VSMCs led to the activation of NFκß signaling. Interestingly, despite producing IL-1ß, trophoblast cells possess only the decoy receptor, whereas, VSMCs possess the IL-1ß signaling receptor. Treatment of VSMCs with exogenous IL-1ß led to a decrease in MYOCARDIN and an increase in phosphorylation of NFκß. The effect of trophoblast cells in the downregulation of MYOCARDIN in VSMCs was reversed by blocking NFκß translocation to the nucleus. Together, these data highlight that trophoblast cells direct VSMC plasticity, and trophoblast-derived IL-1ß is a key player in downregulating MYOCARDIN via the NFκß signaling pathway.

Identification of the role of DAB2 and CXCL8 in uterine spiral artery remodeling in early-onset preeclampsia.

Aberrant remodeling of uterine spiral arteries (SPA) is strongly associated with the pathogenesis of early-onset preeclampsia (EOPE). However, the complexities of SPA transformation remain inadequately understood. We conducted a single-cell RNA sequencing analysis of whole placental tissues derived from patients with EOPE and their corresponding controls, identified DAB2 as a key gene of interest and explored the mechanism underlying the communication between Extravillous trophoblast cells (EVTs) and decidual vascular smooth muscle cells (dVSMC) through cell models and a placenta-decidua coculture (PDC) model in vitro. DAB2 enhanced the motility and viability of HTR-8/SVneo cells. After exposure to conditioned medium (CM) from HTR-8/SVneoshNC cells, hVSMCs exhibited a rounded morphology, indicative of dedifferentiation, while CM-HTR-8/SVneoshDAB2 cells displayed a spindle-like morphology. Furthermore, the PDC model demonstrated that CM-HTR-8/SVneoshDAB2 was less conducive to vascular remodeling. Further in-depth mechanistic investigations revealed that C-X-C motif chemokine ligand 8 (CXCL8, also known as IL8) is a pivotal regulator governing the dedifferentiation of dVSMC. DAB2 expression in EVTs is critical for orchestrating the phenotypic transition and motility of dVSMC. These processes may be intricately linked to the CXCL8/PI3K/AKT pathway, underscoring its central role in intricate SPA remodeling.

Maternal serum PlGF associates with 3D power doppler ultrasound markers of utero-placental vascular development in the first trimester: the rotterdam periconception cohort.

OBJECTIVE (S): Circulating angiogenic factors are used for prediction of placenta-related complications, but their associations with first-trimester placental development is unknown. This study investigates associations between maternal angiogenic factors and utero-placental vascular volume (uPVV) and utero-placental vascular skeleton (uPVS) as novel imaging markers of volumetric and morphologic (branching) development of the first-trimester utero-placental vasculature. METHODS: In 185 ongoing pregnancies from the VIRTUAL Placenta study, a subcohort of the ongoing prospective Rotterdam Periconception cohort, three-dimensional power Doppler ultrasounds of the placenta were obtained at 7-9-11 weeks gestational age (GA). The uPVV was measured as a parameter of volumetric development and reported the vascular quantity in cm3. The uPVS was generated as a parameter of morphologic (branching) development and reported the number of end-, bifurcation- crossing- or vessel points and total vascular length. At 11 weeks GA, maternal serum biomarkers suggested to reflect placental (vascular) development were assessed: placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng). sFlt-1/PlGF and sEng/PlGF ratios were calculated. Multivariable linear regression with adjustments was used to estimate associations between serum biomarkers and uPVV and uPVS trajectories. RESULTS: Serum PlGF was positively associated with uPVV and uPVS development (uPVV: ß = 0.39, 95% CI = 0.15;0.64; bifurcation points: ß = 4.64, 95% CI = 0.04;9.25; crossing points: ß = 4.01, 95% CI = 0.65;7.37; total vascular length: ß = 13.33, 95% CI = 3.09;23.58, all p-values < 0.05). sEng/PlGF ratio was negatively associated with uPVV and uPVS development. We observed no associations between sFlt-1, sEng or sFlt-1/PlGF ratio and uPVV and uPVS development. CONCLUSION(S): Higher first-trimester maternal serum PlGF concentration is associated with increased first-trimester utero-placental vascular development as reflected by uPVV and uPVS. Clinical trial registration number Dutch Trial Register NTR6854.

Human amniotic epithelial cells improve uterine spiral artery remodeling to ameliorate preeclampsia in a rat model†.

Preeclampsia (PE) is a multisystem pregnancy disorder characterized by impaired remodeling of placental spiral arteries, which leads to the release of pro-inflammatory cytokines and anti-angiogenic agents. However, treatment options for PE are limited, with termination of pregnancy being the only curative option. In this work, we investigated the effects of human amniotic epithelial cells (hAECs) in PE rat model. The rats were induced with lipopolysaccharide (LPS) on gestational day 14.5 followed by injection of hAECs and human umbilical cord mesenchymal stem cells 24 h later. The hAECs treatment resulted in a reduction in blood pressure and proteinuria in the PE rat model. Furthermore, hAECs treatment decreased levels of pro-inflammatory cytokines, reduced inflammatory cells aggregation, and alleviated the damage to placental spiral arteries by downregulating the expression of anti-angiogenic factor and upregulating proangiogenic factor. In vitro experiments confirmed that hAECs treatment restored the proliferation, migration, and angiogenesis of LPS-damaged human umbilical vein endothelial cells. Additionally, hAECs treatment had positive effects on fetal weight and neurological development in the PE group, with no negative effects on the physical development or fertility of offspring rats. These results suggested that hAECs transplantation may be a novel adjuvant therapeutic strategy for PE by reducing the inflammatory and enhancing placental spiral artery angiogenesis.

Early spiral arteriole remodeling in the uterine-placental interface: A rat model.

The mammalian placenta's interface with the parent is a richly vascularized tissue whose development relies upon communication between many different cell types within the uterine microenvironment. The uterine blood vessels of the interface are reshaped during pregnancy into wide-bore, flaccid vessels that convey parental blood to the exchange region of the placenta. Invasive trophoblast as well as parental uterine macrophages and Natural Killer cells are involved in the stepwise remodeling of these vessels and their respective contributions to this crucial process are still being delineated. However, the earliest steps in arteriole remodeling are understudied as they are difficult to study in humans, and other species lack the deep trophoblast invasion that is so prominent a feature of placentation in humans. Here, we further characterize the rat, with deep hemochorial placentation akin to humans, as a model system in which to tease apart the earliest, relatively understudied events in spiral arteriole remodeling. We show that the rat uterine-placental interface increases in size and vascularity rapidly, before trophoblast invasion. The remodeling stages in the arterioles of the rat uterine-placental interface follow a sequence of anatomical changes similar to those in humans, and there are changes to the arterioles' muscular tunica media prior to the marked influx of immune cells. The rat is a tractable model in which to better understand the cell/cell interactions occurring in vivo in an intact tissue microenvironment over time.

Morphologic development of the first-trimester utero-placental vasculature is positively associated with embryonic and fetal growth: the Rotterdam Periconception Cohort.

STUDY QUESTION: Is morphologic development of the first-trimester utero-placental vasculature associated with embryonic growth and development, fetal growth, and birth weight percentiles? SUMMARY ANSWER: Using the utero-placental vascular skeleton (uPVS) as a new imaging marker, this study reveals morphologic development of the first-trimester utero-placental vasculature is positively associated with embryonic growth and development, fetal growth, and birth weight percentiles. WHAT IS KNOWN ALREADY: First-trimester development of the utero-placental vasculature is associated with placental function, which subsequently impacts embryonic and fetal ability to reach their full growth potential. The attribution of morphologic variations in the utero-placental vascular development, including the vascular structure and branching density, on prenatal growth remains unknown. STUDY DESIGN, SIZE, DURATION: This study was conducted in the VIRTUAL Placental study, a subcohort of 214 ongoing pregnancies, embedded in the prospective observational Rotterdam Periconception Cohort (Predict study). Women were included before 10 weeks gestational age (GA) at a tertiary referral hospital in The Netherlands between January 2017 and March 2018. PARTICIPANTS/MATERIALS, SETTING, METHODS: We obtained three-dimensional power Doppler volumes of the gestational sac including the embryo and the placenta at 7, 9, and 11 weeks of gestation. Virtual Reality-based segmentation and a recently developed skeletonization algorithm were applied to the power Doppler volumes to generate the uPVS and to measure utero-placental vascular volume (uPVV). Absolute vascular morphology was quantified by assigning a morphologic characteristic to each voxel in the uPVS (i.e. end-, bifurcation-crossing-, or vessel point). Additionally, total vascular length (mm) was calculated. The ratios of the uPVS characteristics to the uPVV were calculated to determine the density of vascular branching. Embryonic growth was estimated by crown-rump length and embryonic volume. Embryonic development was estimated by Carnegie stages. Fetal growth was measured by estimated fetal weight in the second and third trimester and birth weight percentiles. Linear mixed models were used to estimate trajectories of longitudinal measurements. Linear regression analysis with adjustments for confounders was used to evaluate associations between trajectories of the uPVS and prenatal growth. Groups were stratified for conception method (natural/IVF-ICSI conceptions), fetal sex (male/female), and the occurrence of placenta-related complications (yes/no). MAIN RESULTS AND THE ROLE OF CHANCE: Increased absolute vascular morphologic development, estimated by positive random intercepts of the uPVS characteristics, is associated with increased embryonic growth, reflected by crown-rump length (endpoints ß = 0.017, 95% CI [0.009; 0.025], bifurcation points ß = 0.012, 95% CI [0.006; 0.018], crossing points ß = 0.017, 95% CI [0.008; 0.025], vessel points ß = 0.01, 95% CI [0.002; 0.008], and total vascular length ß = 0.007, 95% CI [0.003; 0.010], and similarly with embryonic volume and Carnegie stage, all P-values ≤ 0.01. Density of vascular branching was negatively associated with estimated fetal weight in the third trimester (endpoints: uPVV ß = -94.972, 95% CI [-185.245; -3.698], bifurcation points: uPVV ß = -192.601 95% CI [-360.532; -24.670]) and birth weight percentiles (endpoints: uPVV ß = -20.727, 95% CI [-32.771; -8.683], bifurcation points: uPVV ß -51.097 95% CI [-72.257; -29.937], and crossing points: uPVV ß = -48.604 95% CI [-74.246; -22.961])), all P-values < 0.05. After stratification, the associations were observed in natural conceptions specifically. LIMITATION, REASONS FOR CAUTION: Although the results of this prospective observational study clearly demonstrate associations between first-trimester utero-placental vascular morphologic development and prenatal growth, further research is required before we can draw firm conclusions about a causal relationship. WIDER IMPLICATIONS OF THE FINDINGS: Our findings support the hypothesis that morphologic variations in utero-placental vascular development play a role in the vascular mechanisms involved in embryonic and fetal growth and development. Application of the uPVS could benefit our understanding of the pathophysiology underlying placenta-related complications. Future research should focus on the clinical applicability of the uPVS as an imaging marker for the early detection of fetal growth restriction. STUDY FUNDING/COMPETING INTEREST(S): This research was funded by the Department of Obstetrics and Gynecology of the Erasmus MC, University Medical Centre, Rotterdam, The Netherlands. There are no conflicts of interest. TRIAL REGISTRATION NUMBER: Registered at the Dutch Trial Register (NTR6854).

B-flow/spatiotemporal image correlation M-mode ultrasound provides novel method to quantify spiral artery remodeling during normal human pregnancy.

OBJECTIVES: During human pregnancy, placental extravillous trophoblasts replace vascular smooth muscle and elastic tissue within the walls of the uterine spiral arteries, thereby remodeling them into distensible low-resistance vessels to promote placental perfusion. The present study determined whether B-flow/spatiotemporal image correlation (STIC) M-mode ultrasonography provides an in-vivo imaging method able to digitally quantify spiral artery luminal distensibility as a physiological index of spiral artery remodeling during the advancing stages of normal human pregnancy. METHODS: A prospective, longitudinal, observational study was conducted to quantify spiral artery distensibility (i.e. vessel luminal diameter at systole minus diameter at diastole) by B-flow/STIC M-mode ultrasonography during the first, second and third trimesters in 290 women exhibiting a normal pregnancy. Maternal serum levels of placental growth factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1), growth factors that modulate important events in spiral artery remodeling, were quantified in a subset of the women in the first, second and third trimesters of pregnancy. RESULTS: Median (interquartile range (IQR)) spiral artery distensibility increased progressively between the first (0.17 (0.14-0.21) cm), second (0.23 (0.18-0.28) cm) and third (0.26 (0.21-0.35) cm) trimesters of pregnancy (P < 0.0001 for all). Median (IQR) spiral artery volume flow increased progressively between the first (2.49 (1.38-4.99) mL/cardiac cycle), second (3.86 (2.06-6.91) mL/cardiac cycle) and third (7.79 (3.83-14.98) mL/cardiac cycle) trimesters (P < 0.001 for all). In accordance with the elevation in spiral artery distensibility, the median (IQR) ratio of serum PlGF/sFlt-1 × 103 levels increased between the first (7.2 (4.5-10.0)), second (22.7 (18.6-42.2)) and third (56.2 (41.9-92.5)) trimesters (P < 0.001 for all). CONCLUSIONS: The present study shows that B-flow/STIC M-mode ultrasonography provides an in-vivo imaging technology to quantify digitally the structural and physiological expansion of the walls of the spiral arteries during the cardiac cycle as a consequence of their transformation into compliant vessels during advancing stages of normal human pregnancy. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Intersection of regulatory pathways controlling hemostasis and hemochorial placentation.

Hemochorial placentation is characterized by the development of trophoblast cells specialized to interact with the uterine vascular bed. We utilized trophoblast stem (TS) cell and mutant rat models to investigate regulatory mechanisms controlling trophoblast cell development. TS cell differentiation was characterized by acquisition of transcript signatures indicative of an endothelial cell-like phenotype, which was highlighted by the expression of anticoagulation factors including tissue factor pathway inhibitor (TFPI). TFPI localized to invasive endovascular trophoblast cells of the rat placentation site. Disruption of TFPI in rat TS cells interfered with development of the endothelial cell-like endovascular trophoblast cell phenotype. Similarly, TFPI was expressed in human invasive/extravillous trophoblast (EVT) cells situated within first-trimester human placental tissues and following differentiation of human TS cells. TFPI was required for human TS cell differentiation to EVT cells. We next investigated the physiological relevance of TFPI at the placentation site. Genome-edited global TFPI loss-of-function rat models revealed critical roles for TFPI in embryonic development, resulting in homogeneous midgestation lethality prohibiting analysis of the role of TFPI as a regulator of the late-gestation wave of intrauterine trophoblast cell invasion. In vivo trophoblast-specific TFPI knockdown was compatible with pregnancy but had profound effects at the uterine-placental interface, including restriction of the depth of intrauterine trophoblast cell invasion while leading to the accumulation of natural killer cells and increased fibrin deposition. Collectively, the experimentation implicates TFPI as a conserved regulator of invasive/EVT cell development, uterine spiral artery remodeling, and hemostasis at the maternal-fetal interface.

Pathologic maternal and neonatal outcomes associated with programmed embryo transfer: potential etiologies and strategies for prevention.

PURPOSE: In the first of two companion papers, we comprehensively reviewed the recent evidence in the primary literature, which addressed the increased prevalence of hypertensive disorders of pregnancy, late-onset or term preeclampsia, fetal overgrowth, postterm birth, and placenta accreta in women conceiving by in vitro fertilization. The preponderance of evidence implicated frozen embryo transfer cycles and, specifically, those employing programmed endometrial preparations, in the higher risk for these adverse maternal and neonatal pregnancy outcomes. Based upon this critical appraisal of the primary literature, we formulate potential etiologies and suggest strategies for prevention in the second article. METHODS: Comprehensive review of primary literature. RESULTS: Presupposing significant overlap of these apparently diverse pathological pregnancy outcomes within subjects who conceive by programmed autologous FET cycles, shared etiologies may be at play. One plausible but clearly provocative explanation is that aberrant decidualization arising from suboptimal endometrial preparation causes greater than normal trophoblast invasion and myometrial spiral artery remodeling. Thus, overly robust placentation produces larger placentas and fetuses that, in turn, lead to overcrowding of villi within the confines of the uterine cavity which encroach upon intervillous spaces precipitating placental ischemia, oxidative and syncytiotrophoblast stress, and, ultimately, late-onset or term preeclampsia. The absence of circulating corpus luteal factors like relaxin in most programmed cycles might further compromise decidualization and exacerbate the maternal endothelial response to deleterious circulating placental products like soluble fms-like tyrosine kinase-1 that mediate disease manifestations. An alternative, but not mutually exclusive, determinant might be a thinner endometrium frequently associated with programmed endometrial preparations, which could conspire with dysregulated decidualization to elicit greater than normal trophoblast invasion and myometrial spiral artery remodeling. In extreme cases, placenta accreta could conceivably arise. Though lower uterine artery resistance and pulsatility indices observed during early pregnancy in programmed embryo transfer cycles are consistent with this initiating event, quantitative analyses of trophoblast invasion and myometrial spiral artery remodeling required to validate the hypothesis have not yet been conducted. CONCLUSIONS: Endometrial preparation that is not optimal, absent circulating corpus luteal factors, or a combination thereof are attractive etiologies; however, the requisite investigations to prove them have yet to be undertaken. Presuming that in ongoing RCTs, some or all adverse pregnancy outcomes associated with programmed autologous FET are circumvented or mitigated by employing natural or stimulated cycles instead, then for women who can conceive using these regimens, they would be preferable. For the 15% or so of women who require programmed FET, additional research as suggested in this review is needed to elucidate the responsible mechanisms and develop preventative strategies.

Human Placenta and Evolving Insights into Pathological Changes of Preeclampsia: A Comprehensive Review of the Last Decade.

The placenta, the foremost and multifaceted organ in fetal and maternal biology, is pivotal in facilitating optimal intrauterine fetal development. Remarkably, despite its paramount significance, the placenta remains enigmatic, meriting greater comprehension given its central influence on the health trajectories of both the fetus and the mother. Preeclampsia (PE) and intrauterine fetal growth restriction (IUGR), prevailing disorders of pregnancy, stem from compromised placental development. PE, characterized by heightened mortality and morbidity risks, afflicts 5-7% of global pregnancies, its etiology shrouded in ambiguity. Pertinent pathogenic hallmarks of PE encompass inadequate restructuring of uteroplacental spiral arteries, placental ischemia, and elevated levels of vascular endothelial growth factor receptor-1 (VEGFR-1), also recognized as soluble FMS-like tyrosine kinase-1 (sFlt-1). During gestation, the placental derivation of sFlt-1 accentuates its role as an inhibitory receptor binding to VEGF-A and placental growth factor (PlGF), curtailing target cell accessibility. This review expounds upon the placenta's defining cellular component of the trophoblast, elucidates the intricacies of PE pathogenesis, underscores the pivotal contribution of sFlt-1 to maternal pathology and fetal safeguarding, and surveys recent therapeutic strides witnessed in the past decade.

Cellular Prion protein moonlights vascular smooth muscle cell fate: Surveilled by trophoblast cells.

Uterine spiral artery remodeling (uSAR) is a hallmark of hemochorial placentation. Compromised uSAR leads to adverse pregnancy outcomes. Salient developmental events involved in uSAR are active areas of research and include (a) trophendothelial cell invasion into the spiral arteries, selected demise of endothelial cells; (b) de-differentiation of vascular smooth muscle cells (VSMC); and (c) migration and/or death of VSMCs surrounding spiral arteries. Here we demonstrated that cellular prion (PRNP) is expressed in the rat metrial gland, the entry point of spiral arteries with the highest expression on E16.5, the day at which trophoblast invasion peaks. PRNP is expressed in VSMCs that drift away from the arterial wall. RNA interference of Prnp functionally restricted migration and invasion of rat VSMCs. Furthermore, PRNP interacted with two migration-promoting factors, focal adhesion kinase (FAK) and platelet-derived growth factor receptor-ß (PDGFR-ß), forming a ter-molecular complex in both the metrial gland and A7r5 cells. The presence of multiple putative binding site of odd skipped related-1 (OSR1) transcription factor on the Prnp promoter was observed using in silico promoter analysis. Ectopic overexpression of OSR1 increased, and knockdown of OSR1 decreased expression of PRNP in VSMCs. Coculture of VSMCs with rat primary trophoblast cells decreased the levels of OSR1 and PRNP. Interestingly, PRNP knockdown led to apoptotic death in ~9% of VSMCs and activated extrinsic apoptotic pathways. PRNP interacts with TRAIL-receptor DR4 and protects VSMCs from TRAIL-mediated apoptosis. These results highlight the biological functions of PRNP in VSMC cell-fate determination during uteroplacental development, an important determinant of healthy pregnancy outcome.

Alpha-2-macroglobulin is involved in the occurrence of early-onset pre-eclampsia via its negative impact on uterine spiral artery remodeling and placental angiogenesis.

BACKGROUND: Pre-eclampsia (PE) is one of the leading causes of maternal and fetal morbidity/mortality during pregnancy, and alpha-2-macroglobulin (A2M) is associated with inflammatory signaling; however, the pathophysiological mechanism by which A2M is involved in PE development is not yet understood. METHODS: Human placenta samples, serum, and corresponding clinical data of the participants were collected to study the pathophysiologic mechanism underlying PE. Pregnant Sprague-Dawley rats were intravenously injected with an adenovirus vector carrying A2M via the tail vein on gestational day (GD) 8.5. Human umbilical artery smooth muscle cells (HUASMCs), human umbilical vein endothelial cells (HUVECs), and HTR-8/SVneo cells were transfected with A2M-expressing adenovirus vectors. RESULTS: In this study, we demonstrated that A2M levels were significantly increased in PE patient serum, uterine spiral arteries, and feto-placental vasculature. The A2M-overexpression rat model closely mimicked the characteristics of PE (i.e., hypertension in mid-to-late gestation, histological and ultrastructural signs of renal damage, proteinuria, and fetal growth restriction). Compared to the normal group, A2M overexpression significantly enhanced uterine artery vascular resistance and impaired uterine spiral artery remodeling in both pregnant women with early-onset PE and in pregnant rats. We found that A2M overexpression was positively associated with HUASMC proliferation and negatively correlated with cell apoptosis. In addition, the results demonstrated that transforming growth factor beta 1 (TGFß1) signaling regulated the effects of A2M on vascular muscle cell proliferation described above. Meanwhile, A2M overexpression regressed rat placental vascularization and reduced the expression of angiogenesis-related genes. In addition, A2M overexpression reduced HUVEC migration, filopodia number/length, and tube formation. Furthermore, HIF-1α expression was positively related to A2M, and the secretion of sFLT-1 and PIGF of placental origin was closely related to PE during pregnancy or A2M overexpression in rats. CONCLUSIONS: Our data showed that gestational A2M overexpression can be considered a contributing factor leading to PE, causing detective uterine spiral artery remodeling and aberrant placental vascularization.

Conventional natural killer cells control vascular remodeling in the uterus during pregnancy by acidifying the extracellular matrix with a2V.

Vascular remodeling within the uterus immediately before and during early pregnancy increases blood flow in the fetus and prevents the development of gestational hypertension. Tissue-resident natural killer (trNK) cells secrete pro-angiogenic growth factors but are insufficient for uterine artery (UtA) remodeling in the absence of conventional natural killer (cNK) cells. Matrix metalloproteinase-9 (MMP9) is activated in acidic environments to promote UtA remodeling. We have previously shown that ATPase a2V plays a role in regulating the function of cNK cells during pregnancy. We studied the effect of a2V deletion on uterine cNK cell populations and pregnancy outcomes in VavCrea2Vfl/fl mice, where a2V is conditionally deleted in hematopoietic stem cells. Conventional NKcells were reduced but trNK cells were retained in implantation sites at gestational day 9.5, and UtA remodeling was inhibited despite no differences in concentrations of pro-angiogenic growth factors. The ratio of pro-MMP9 to total was significantly elevated in VavCrea2Vfl/fl mice, and MMP9 activity was significantly reduced. The pH of implantation sites was significantly elevated in VavCrea2Vfl/fl mice. We concluded that the role of cNK cells in the uterus is to acidify the extracellular matrix (ECM) using a2V, which activates MMP9 to degrade the ECM, release bound pro-angiogenic growth factors, and contribute to UtA remodeling. Our results are significant for the understanding of the development of gestational hypertension.

Extravillous trophoblast cell-derived exosomes induce vascular smooth muscle cell apoptosis via a mechanism associated with miR-143-3p.

The remodeling of uterine spiral arteries is a complex process requiring the dynamic action of various cell types. During early pregnancy, extravillous trophoblast (EVT) cells differentiate and invade the vascular wall, replacing the vascular smooth muscle cells (VSMCs). Several in vitro studies have shown that EVT cells play an important role in promoting VSMC apoptosis, however, the mechanism underlying this process is not fully understood. In this study, we demonstrated that EVT-conditioned media and EVT-derived exosomes could induce VSMC apoptosis. Through data mining and experimental verification, it was demonstrated that the EVT exosome miR-143-3p induced VSMC apoptosis in both VSMCs and a chorionic plate artery (CPA) model. Furthermore, FAS ligand was also expressed on the EVT exosomes and may play a co-ordinated role in apoptosis induction. These data clearly demonstrated that VSMC apoptosis is mediated by EVT-derived exosomes and their cargo of miR-143-3p as well as their cell surface presentation of FASL. This finding increases our understanding of the molecular mechanisms underlying the regulation of VSMC apoptosis during spiral artery remodeling.

Origins of abnormal placentation: why maternal veins must not be forgotten.

The importance of uterine microvascular adaptations during placentation in pregnancy has been well established for decades. Inadequate dilatation of spiral arteries is associated with gestational complications, such as preeclampsia and/or intrauterine growth restriction. More recently, it has become clear that trophoblast cells invade and adapt decidual veins and lymphatic vessels 1 month before spiral arteries become patent and before intervillous space perfusion starts. Normal intervillous space hemodynamics is characterized by high volume flow at low velocity and pressure in the interseptal compartments surrounding the chorionic villi, hereby facilitating efficient maternal-fetal exchange. In case of shallow decidual vein dilatation, intervillous arterial supply exceeds venous drainage. This will cause congestion in the interseptal compartments with subsequently reduced perfusion and increased pressure. An efficient mechanism to counteract venous congestion and safeguard the viability of the conceptus is by reducing arterial inflow via shallow dilatation of the spiral arteries. This review made the case for intervillous space congestion as an unexplored trigger for inadequate spiral artery dilatation during the placentation process, eventually leading to abnormal systemic circulatory dysfunctions. An abnormal maternal venous function can result from an abnormal maternal immune response to paternal antigens with an imbalanced release of vasoactive mediators or can exist before conception. To get the full picture of abnormal placentation, maternal veins must not be forgotten.

Longitudinal assessment of spiral and uterine arteries in normal pregnancy using novel ultrasound tool.

OBJECTIVES: To use superb microvascular imaging (SMI) to evaluate longitudinally spiral artery (SA) and uterine artery (UtA) vascular adaptation in normal human pregnancy, and to develop reference ranges for use at various gestational ages throughout pregnancy. METHODS: The data for this study were obtained from the National Institutes of Health (NIH)-funded Human Placenta Project. Women aged 18-35 years, with a body mass index < 30 kg/m2 , without comorbidities, with a singleton gestation conceived spontaneously, and gestational age at or less than 13 + 6 weeks were eligible for inclusion. The current analysis was restricted to uncomplicated pregnancies carried to term. Exclusion criteria included maternal or neonatal complications, fetal or umbilical cord anomalies, abnormal placental implantation or delivery < 37 weeks. Women who fulfilled the inclusion criteria formed the reference population of the Human Placenta Project study. Each participant underwent eight ultrasound examinations during pregnancy. The pulsatility index (PI) of both the left and right UtA were obtained twice for each artery and the presence or absence of a notch was noted. Using SMI technology, the total number of SA imaged was recorded in a sagittal placental section at the level of cord insertion. The PI and peak systolic velocity (PSV) were also measured in a total of six SA, including two in the central portion of the placenta, two peripherally towards the uterine fundal portion, and two peripherally towards the lower uterine segment. RESULTS: A total of 90 women fulfilled the study criteria. Maternal UtA-PI decreased throughout the first half of pregnancy from a mean ± SD of 1.39 ± 0.50 at 12-13 weeks' gestation to 0.88 ± 0.24 at 20-21 weeks' gestation. The mean number of SA visualized in a sagittal plane of the placenta increased from 8.83 ± 2.37 in the first trimester to 16.99 ± 3.31 in the late-third trimester. The mean SA-PI was 0.57 ± 0.12 in the first trimester and decreased progressively during the second trimester, reaching a nadir of 0.40 ± 0.10 at 24-25 weeks, and remaining constant until the end of pregnancy. SA-PSV was highest in early pregnancy with a mean of 57.16 ± 14.84 cm/s at 12-13 weeks' gestation, declined to a mean of 49.38 ± 17.88 cm/s at 20-21 weeks' gestation and continued to trend downward for the remainder of pregnancy, reaching a nadir of 34.50 ± 15.08 cm/s at 36-37 weeks' gestation. A statistically significant correlation was noted between SA-PI and UtA-PI (r = 0.5633; P < 0.001). Multilevel regression models with natural cubic splines were used to create reference ranges of SA-PSV and SA-PI for given gestational ages. CONCLUSION: From early gestation, we have demonstrated the ability to image and quantify SA blood flow in normal pregnancy, and have developed reference ranges for use at various gestational ages throughout pregnancy. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Natriuretic Peptide Signaling in Uterine Biology and Preeclampsia.

Endometrial decidualization is a uterine process essential for spiral artery remodeling, embryo implantation, and trophoblast invasion. Defects in endometrial decidualization and spiral artery remodeling are important contributing factors in preeclampsia, a major disorder in pregnancy. Atrial natriuretic peptide (ANP) is a cardiac hormone that regulates blood volume and pressure. ANP is also generated in non-cardiac tissues, such as the uterus and placenta. In recent human genome-wide association studies, multiple loci with genes involved in natriuretic peptide signaling are associated with gestational hypertension and preeclampsia. In cellular experiments and mouse models, uterine ANP has been shown to stimulate endometrial decidualization, increase TNF-related apoptosis-inducing ligand expression and secretion, and enhance apoptosis in arterial smooth muscle cells and endothelial cells. In placental trophoblasts, ANP stimulates adenosine 5'-monophosphate-activated protein kinase and the mammalian target of rapamycin complex 1 signaling, leading to autophagy inhibition and protein kinase N3 upregulation, thereby increasing trophoblast invasiveness. ANP deficiency impairs endometrial decidualization and spiral artery remodeling, causing a preeclampsia-like phenotype in mice. These findings indicate the importance of natriuretic peptide signaling in pregnancy. This review discusses the role of ANP in uterine biology and potential implications of impaired ANP signaling in preeclampsia.

Histopathology of fused triplet placenta in rat.

A fused triplet placenta was observed in a Wistar Hannover rat on gestation day 15. Each placenta (referred to as PL-A, PL-B, and PL-C) of this fused placenta was attached to one fetus each, but their fetal weights were lower than that of the fetus attached to the only normal placenta (referred to as PL-N) in this dam. Histopathologically, thinning of the trophoblastic septa and dilatation of the maternal sinusoid in the labyrinth zone were observed in PL-B and PL-C, but not in PL-A or PL-N. The points of placental fusion were at the junctional zone derived from each side of the placenta without connective tissues, and the septum was composed of trophoblastic giant cells. Although PL-A had a solitary metrial gland, PL-B and PL-C shared one metrial gland with one spiral artery terminus branching towards each labyrinth zone.

Uterine NK cell functions at maternal-fetal interface†.

During pregnancy, maternal decidual tissue interacts with fetal trophoblasts. They constitute the maternal-fetal interface responsible for supplying nutrition to the fetus. Uterine natural killer (uNK) cells are the most abundant immune cells at the maternal-fetal interface during early pregnancy and play critical roles throughout pregnancy. This review provides current knowledge about the functions of uNK cells. uNK cells have been shown to facilitate remodeling of the spiral artery, control the invasion of extravillous trophoblast (EVT) cells, contribute to the induction and maintenance of immune tolerance, protect against pathogen infection, and promote fetal development. Pregnancy-trained memory of uNK cells improves subsequent pregnancy outcomes. In addition, this review describes the distinct functions of three uNK cell subsets: CD27-CD11b-, CD27+, and CD27-CD11b+ uNK cells.

Failure of physiological transformation and spiral artery atherosis: their roles in preeclampsia.

Physiological transformation with remodeling of the uteroplacental spiral arteries is key to a successful placentation and normal placental function. It is an intricate process that involves, but is not restricted to, complex interactions between maternal decidual immune cells and invasive trophoblasts in the uterine wall. In normal pregnancy, the smooth muscle cells of the arterial tunica media of uteroplacental spiral arteries are replaced by invading trophoblasts and fibrinoid, and the arterial diameter increases 5- to 10-fold. Poor remodeling of the uteroplacental spiral arteries is linked to early-onset preeclampsia and several other major obstetrical syndromes, including fetal growth restriction, placental abruption, and spontaneous preterm premature rupture of membranes. Extravillous endoglandular and endovenous trophoblast invasions have recently been put forth as potential contributors to these syndromes as well. The well-acknowledged disturbed extravillous invasion of maternal spiral arteries in preeclampsia is summarized, as are briefly novel concepts of disturbed extravillous endoglandular and endovenous trophoblast invasions. Acute atherosis is a foam cell lesion of the uteroplacental spiral arteries associated with poor remodeling. It shares some morphologic features with early stages of atherosclerosis, but several molecular differences between these lesions have also recently been revealed. Acute atherosis is most prevalent at the maternal-fetal interface, at the tip of the spiral arteries. The localization of acute atherosis downstream of poorly remodeled arteries suggests that alterations in blood flow may trigger inflammation and foam cell development. Acute atherosis within the decidua basalis is not, however, confined to unremodeled areas of spiral arteries or to hypertensive disorders of pregnancy and may even be present in some clinically uneventful pregnancies. Given that foam cells of atherosclerotic lesions are known to arise from smooth muscle cells or macrophages activated by multiple types of inflammatory stimulation, we have proposed that multiple forms of decidual vascular inflammation may cause acute atherosis, with or without poor remodeling and/or preeclampsia. Furthermore, we propose that acute atherosis may develop at different gestational ages, depending on the type and degree of the inflammatory insult. This review summarizes the current knowledge of spiral artery remodeling defects and acute atherosis in preeclampsia. Some controversies will be presented, including endovascular and interstitial trophoblast invasion depths, the concept of 2-stage trophoblast invasion, and whether the replacement of maternal spiral artery endothelium by fetal endovascular trophoblasts is permanent. We will discuss the role of acute atherosis in the pathophysiology of preeclampsia and short- and long-term health correlates. Finally, we suggest future opportunities for research on this intriguing uteroplacental interface between the mother and fetus.