Placental Microvascular Endothelial Cells Research Articles

HAND1 knockdown disrupts trophoblast global geneexpression.

Congenital heart disease (CHD) affects nearly 1% of births annually, and CHD pregnancies carry increased risk of developing pathologies of abnormal placentation. We previously reported significant developmental impacts of disrupting Hand1, a gene associated with CHD, expression in placenta trophoblast and endothelial cells in multiple mouse models. In this study, we aimed to build upon this knowledge and characterize the mechanistic impacts of disrupting HAND1 on human placenta trophoblast and vascular endothelial cell gene expression. HAND1 gene expression was silenced in BeWo cells, a choriocarcinoma model of human cytotrophoblasts, (n=3-9 passages) and isolated human placental microvascular endothelial cells (HPMVEC; n=3 passages), with HAND1 siRNA for 96 h. Cells were harvested, mRNA isolated and RNA sequencing performed using the Illumina NextSeq 550 platform. Normalization and differential gene expression analyses were conducted using general linear modeling in edgeR packages. Statistical significance was determined using a log2 fold change of >1.0 or < -1.0 and unadjusted p-value ≤0.05. Panther DB was used for overrepresentation analysis, and String DB for protein association network analysis. There was downregulation of 664 genes, and upregulation of 59 genes in BeWo cells with direct HAND1 knockdown. Overrepresentation analysis identified disruption to pathways including cell differentiation, localization, and cell projection organization. In contrast, only seven genes were changed with direct HAND1 knockdown in HPMVECs. Disruption to HAND1 expression significantly alters gene expression profile in trophoblast but not endothelial cells. This data provides further evidence that future studies on genetic perturbations in CHDs should consider the extra-embryonic tissue in addition to the fetal heart.

Regulation of Proinflammatory Molecules and Tissue Factor by SARS-CoV-2 Spike Protein in Human Placental Cells: Implications for SARS-CoV-2 Pathogenesis in Pregnant Women.

SARS-CoV-2 infects cells via binding to ACE2 and TMPRSS2, which allows the virus to fuse with host cells. The viral RNA is detected in the placenta of SARS-CoV-2-infected pregnant women and infection is associated with adverse pregnancy complications. Therefore, we hypothesize that SARS-CoV-2 infection of placental cells induces pro-inflammatory cytokine release to contribute to placental dysfunction and impaired pregnancy outcomes. First, expression of ACE2 and TMPRSS2 was measured by qPCR in human primary cultured term cytotrophoblasts (CTBs), syncytiotrophoblast (STBs), term and first trimester decidual cells (TDCs and FTDCs, respectively), endometrial stromal cells (HESCs) as well as trophoblast cell lines HTR8, JEG3, placental microvascular endothelial cells (PMVECs) and endometrial endothelial cells (HEECs). Later, cultured HTR8, JEG3, PMVECs and HEECs were treated with 10, 100, 1000 ng/ml of recombinant (rh-) SARS-CoV-2 S-protein ± 10 ng/ml rh-IFNγ. Pro-inflammatory cytokines IL-1β, 6 and 8, chemokines CCL2, CCL5, CXCL9 and CXCL10 as well as tissue factor (F3), the primary initiator of the extrinsic coagulation cascade, were measured by qPCR as well as secreted IL-6 and IL-8 levels were measured by ELISA. Immunohistochemical staining for SARS-CoV-2 spike protein was performed in placental specimens from SARS-CoV-2–positive and normal pregnancies. ACE2 levels were significantly higher in CTBs and STBs vs. TDCs, FTDCs and HESCs, while TMPRSS2 levels were not detected in TDCs, FTDCs and HESCs. HTR8 and JEG3 express ACE2 and TMPRSS2, while PMVECs and HEECs express only ACE2, but not TMPRSS2. rh-S-protein increased proinflammatory cytokines and chemokines levels in both trophoblast and endothelial cells, whereas rh-S-protein only elevated F3 levels in endothelial cells. rh-IFNγ ± rh-S-protein augments expression of cytokines and chemokines in trophoblast and endothelial cells. Elevated F3 expression by rh-IFNγ ± S-protein was observed only in PMVECs. In placental specimens from SARS-CoV-2-infected mothers, endothelial cells displayed higher immunoreactivity against spike protein. These findings indicated that SARS-CoV-2 infection in placental cells: 1) induces pro-inflammatory cytokine and chemokine release, which may contribute to the cytokine storm observed in severely infected pregnant women and related placental dysfunction; and 2) elevates F3 expression that may trigger systemic or placental thrombosis.

Follistatin dysregulation impaired trophoblast biological functions by GDF11-Smad2/3 axis in preeclampsia placentas

IntroductionPreeclampsia (PE) is one of the main causes of maternal, fetal, and neonatal mortality. So far, the underlying mechanism of this pregnancy-specific syndrome remains unelucidated. The expression of Follistatin (FST) decreased in maternal serum (especially early onset severe PE) and placental trophoblasts of PE patients. However, whether FST-deficiency in preeclamptic placentas alters trophoblast function remains to be determined. MethodsTrophoblast cell lines were cultured in vitro and LV3 short hairpin RNA (shRNA) was used to silence FST. Growth and differentiation factor 11 (GDF11) expression level in placentas and serum were detected by immunohistochemistry and enzyme-linked immune-sorbent assay, respectively. To verify the effect of reduced FST expression on trophoblasts, microRNA-24-3p, which was predicted to target the 3′-untranslated region (3′-UTR) of FST, was screened out, and miR-24-3p mimic, inhibitor was used to regulate FST expression in trophoblasts. ResultsDownregulation of FST significantly enhanced the apoptosis and impaired migration and invasion of trophoblast. Reduced FST caused the upregulation of GDF11 in trophoblasts. Interestingly, GDF11 reduced in preeclamptic placental microvascular endothelial cells. Dysregulation of FST-GDF11-Smad2/3 signaling pathway, leading to increased apoptosis of trophoblast. Expression levels of miR-24-3p, was significantly elevated in preeclamptic placentas. Trophoblast cells transfected with miR-24-3p mimics displayed impaired migration and invasion and increased apoptosis. Treated by miR-24-3p inhibitor, trophoblast cells exhibited rescued function. DiscussionFST-deficiency impaired trophoblast function by upregulating GDF11 levels in trophoblasts. The regulation of FST-GDF11-Smad2/3 axis by microRNAs mimic or inhibitor may be critical to trophoblast function regulation and helps to deepen our understanding of the molecular mechanism of PE.

MiR-125b-5p ameliorates hypoxia/reoxygenation-induced endothelial cell dysfunction and attenuates reduced uterine perfusion pressure-induced hypertension in pregnant rats via targeting BMF

ABSTRACT Background and Purpose MicroRNA-125b-5p (miR-125b-5p) is downregulated in patients with gestational hypertension signs. However, the role of miR-125b-5p in pregnancy-induced hypertension (PIH) remains unknown. Methods The human placental microvascular endothelial cells (HPMECs) have undergone hypoxia and reoxygenation (H/R) treatment to establish PIH cellular model. Rats were performed with reduced uterine perfusion pressure (RUPP) operation to establish PIH animal model. Results MiR-125b-5p promoted viability while inhibited the apoptosis of H/R-treated HPMECs by downregulating BMF. MiR-125b-5p alleviated hypertensive symptoms and improved pregnancy outcomes in RUPP rats. Conclusion MiR-125b-5p ameliorates H/R-induced HPMEC dysfunction and attenuates RUPP-induced hypertension in pregnant rats by downregulating BMF.

MicroRNA-195-5p facilitates endothelial dysfunction by inhibiting vascular endothelial growth factor A in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a common disorder during pregnancy associated with endothelial dysfunction in the placental vasculature. MicroRNAs (miRNAs), which are short noncoding RNAs that modulate post-transcriptional gene expression, affect GDM progression. MiR-195-5p was reported to be a putative biomarker for GDM diagnosis, whose expression was markedly elevated in serum of GDM patients. Therefore, our study intended to explore whether miR-195-5p regulates endothelial cell dysfunction in GDM. Human placental microvascular endothelial cells (hPMECs) were treated with high concentration of glucose to establish an in vitro GDM model. The apoptosis, proliferation and angiogenesis of hPMECs were detected by flow cytometry analysis, CCK-8 assay and tube formation assay. The binding between vascular endothelial growth factor A (VEGFA) and miR-195-5p was verified by luciferase reporter assay. GDM mouse model was established by intraperitoneal injection of streptozocin. Cell apoptosis and the pathological changes in GDM mouse placenta tissues were evaluated by TUNEL staining and HE staining. Gene expression was detected by RT-qPCR. Protein levels were evaluated by western blotting. In this study, miR-195-5p knockdown promoted the proliferation and angiogenesis as well as inhibited the apoptosis of HG-treated hPMECs. MiR-195-5p targeted VEGFA, whose expression was downregulated in HG-treated hPMECs. VEGFA silencing antagonized the influence of miR-195-5p knockdown on the phenotypes of HG-treated hPMECs. Additionally, miR-195-5p inhibition decelerated cell apoptosis and improved pathological changes in GDM mouse placenta tissues. MiR-195-5p level was negatively correlated to VEGFA level in GDM mouse placenta tissues. Overall, miR-195-5p facilitates the endothelial cell dysfunction by inhibiting VEGFA in GDM.

Overexpression of microRNA-100-5p attenuates the endothelial cell dysfunction by targeting HIPK2 under hypoxia and reoxygenation treatment.

MicroRNAs (miRNAs) are important regulators of many cellular processes, and the dysregulation of miRNAs is associated with various diseases. MiR-100-5p is revealed to be downregulated in gestational hypertension, while its underlying regulatory mechanism remains unclear. The pathological condition of gestational hypertension was mimicked by the hypoxia and reoxygenation (H/R) treatment to human placental microvascular endothelial cells (HPMECs). RT-qPCR and western blotting were conducted to detect the mRNA and protein expression of RNAs. HPMEC viability was assessed by CCK-8 assay. HPMEC angiogenesis was examined using tube formation assay. The concentrations of ANG-1 and ANG-2 in HPMECs were detected by ELISA. The binding relationship between miR-100-5p and homeodomain interacting protein kinase 2 (HIPK2) was investigated using luciferase reporter assay. MiR-100-5p was downregulated in HPMECs after H/R treatment. MiR-100-5p overexpression reversed the H/R-induced decrease in viability, angiogenesis of HPMECs. HIPK2 was targeted by miR-100-5p in HPMECs, and miR-100-5p negatively modulated HIPK2 expression at the mRNA and protein levels. MiR-100-5p activated the PI3K/AKT pathway by downregulating HIPK2. Rescue assays demonstrated that miR-100-5p promoted the viability and angiogenesis of H/R treated HPMECs by targeting HIPK2 to activate the PI3K/AKT pathway. MiR-100-5p overexpression inhibits the dysfunction of HPMECs under hypoxia and reoxygenation by downregulating HIPK2 to activate the PI3K/AKT pathway.

Exosomal miR-486-5p derived from human placental microvascular endothelial cells regulates proliferation and invasion of trophoblasts via targeting IGF1

Preeclampsia (PE) is a serious complication of pregnancy. Exosomes are known to be upregulated in PE. In this study, we sought to investigate the effect of miR-486-5p from human placental microvascular endothelial cells, on the function of trophoblast cells. To investigate the function of human placental microvascular endothelial cell (HPVEC)-derived exosomes on trophoblast cells, HPVECs were treated with hypoxia/reoxygenation (H/R). The separation efficiency of exosomes was determined by transmission electron microscopy, nanosight and Western blot. Cell Counting Kit-8, EdU staining, wound-healing, and transwell assay were performed to detect the effect of exosomally transferred miR-486-5p inhibitor on proliferation, migration and invasion of trophoblast cells. MiRDB and dual-luciferase report assay were used to find the target of miR-486-5p. Our data revealed that miR-486-5p was significantly upregulated in H/R-treated HPVEC-Exo, and miR-486-5p was enriched in HPVEC-Exo. miR-486-5p inhibitor carried by HPVEC-Exo significantly inhibited the proliferation, migration and invasion of trophoblast cells. Insulin-like growth factor 1 (IGF1) was found to be the target of miR-486-5p, and IGF1 overexpression notably reversed the effect of miR-486-5p inhibitor from HPVEC-Exo on trophoblast cell function. In summary, H/R-treated HPVEC-derived exosomally expressing miR-486-5p inhibitor significantly inhibited the proliferation, migration and invasion of trophoblast cells via downregulation of IGF1. The findings from the present study may be useful in the development of treatments for PE.

1112HAND1 knockdown disrupts trophoblast but not placental endothelial global gene expression

We previously reported disrupted placental structure, and vascular changes in placentas from fetuses with Congenital Heart Defects. Signaling between trophoblast and villous endothelium is proposed for proper placental development and function. We hypothesize that disruption of genes associated with CHD within the trophoblast impacts fetal endothelium and results in dysregulated placental vasculature in CHD fetuses. A model of human cytotrophoblast, BeWo choriocarcinoma cells and isolated human placental microvascular endothelial cells (HPMVEC) were treated for 48 hrs with HAND1 siRNA/lipofectamine. Additionally, control HPMVECs were exposed to conditioned BeWo media (+/- HAND1) for 48 hrs. Cells were harvested and total RNA isolated. RNA was sequenced on an Illumina NextSeq 550 platform (single end reads 85bp, read depth 25M). The Galaxy Bioinformatic Platform was used for quality control, alignment (Bowtie2) and generation of read counts (Feature Counts). Normalization and differential gene expression analyses were conducted using general linear modeling in edgeR package from Bioconductor. Significance was determined using a fold change cut off of >1.5 and raw p<0.05. Overrepresentation analysis was performed using Panther DB for Reactome pathways and GO terms Direct HAND1 knockdown in the BeWo choriocarcinoma cell line caused downregulation of 632 genes, and upregulation of 102 genes. Overrepresentation analysis identified disruption to pathways including cell differentiation, neurogenesis, localization, and cell projection organization. In contrast, direct HAND1 knockdown in HPMVECs resulted in minimal disruption to global gene expression with differential expression in just 18 genes. Indirect HAND1 disruption did not alter HPMVEC gene expression. Disruption to HAND1 expression significantly alters gene expression profile in trophoblast but not HPMVEC, either directly or indirectly. Disruption to the structure and vasculature of the placenta in cases of CHD is likely primarily due to abnormal trophoblast development.

Inhibition of HIF-1a-mediated TLR4 activation decreases apoptosis and promotes angiogenesis of placental microvascular endothelial cells during severe pre-eclampsia pathogenesis

ObjectiveHypoxia-induced factor 1a (HIF-1a) and Toll-like receptor 4 (TLR4) are involved in pre-eclampsia (PE) pathogenesis. However, little is known about their relationships. This study aimed to investigate the interaction of HIF-1a and TLR4 in PE pathogenesis. MethodsThe expression of HIF-1a and TLR4 were analyzed by qRT-PCR. Celluar PE model was established by hypoxia/reoxygenation treatment of human placental microvascular endothelial cells (hPMEC). Cell proliferation, apoptosis, invasion and migration were analyzed by CCK-8, flow cytometry, Transwell and scratch adhesion test, respectively. Angiogenesis was performed by tube formation, Ang-1 in culture supernatant was analyzed by ELISA. ResultsHIF-1a and TLR4 expression were significantly elevated in placental tissues from early-onset and late-onset severe pre-eclampsia patients compared with control, with increased Bax, TRIF and PUMA, and decreased Bcl-2 and VEGFA; Down-regulation of HIF-1a expression decreased TLR4 expression, promoted proliferation, invasion, migration and angiogenesis but suppressed apoptosis in cellular model. In addition, silencing HIF-1a and TAK232 treatment synergically promoted some more proliferation, invasion, migration and angiogenesis but suppressed apoptosis in cellular model. ConclusionHIF-1a could promote hPMEC apoptosis by regulating TLR4 expression during PE pathogenesis.

Diversity in human placental microvascular endothelial cells and macrovascular endothelial cells

Angiogenesis is fundamental to normal placental development, and aberrant angiogenesis contributes substantially to placental pathologies. Placental angiogenesis is a pivotal process that plays a key mechanistic role in the elaboration of the placental villous tree, which is mainly taken by human placental microvascular endothelial cells (HPMECs), present in the fetal capillaries of chorionic villi, and macrovascular human umbilical vein endothelial cells (HUVECs) also play a role in this process. These are the two types of endothelial cells that form the placenta and differ in morphology and function. The placental vasculature represents a distinct territory that is highly specialized in structure and function. To distinguish the differences between HPMECs and HUVECs, we isolated HPMECs by paramagnetic particle separation and HUVECs through trypsinization and validated their characteristics. Then, we examined their response to fibroblast growth factor 2 (FGF2), vascular endothelial growth factor (VEGF) and endocrine-gland-derived vascular endothelial growth factor (EG-VEGF), as well as the underlying signaling mechanisms and their transcriptomes. We found that cultured HPMECs and HUVECs took up DiI-Ac-LDL and formed capillary-like tube structures on Matrigel. HPMECs and HUVECs had different expressions of eNOS, PROKR1 and PROKR2, and these characteristics substantiate the endothelial nature of cultured cells. FGF2 and VEGF stimulated the proliferation and migration of HPMECs and HUVECs via activation of PI3K/AKT1 and MEK1/MEK2/ERK1/ERK2. Interestingly, EG-VEGF increased the proliferation and migration of HPMECs via only MEK1/MEK2/ERK1/ERK2 and not PI3K/AKT1. Microarray analysis showed that there were some differentially expressed genes between HPMECs and HUVECs. Gene ontology analysis indicated that the differentially expressed genes were highly related to G-protein coupled receptor signaling pathway, angiogenesis, L-lysine transmembrane transport and blood vessel remodeling. These data provided evidence of heterogeneity between microvascular HPMECs and macrovascular HUVECs that most likely reflected significant differences in endothelial cell function in the two different cellular environments.

Upregulation of DAPK2 ameliorates oxidative damage and apoptosis of placental cells in hypertensive disorder complicating pregnancy by suppressing human placental microvascular endothelial cell autophagy through the mTOR signaling pathway

Death-associated protein kinase 2 (DAPK2) has indicated functional roles in cellular processes, including survival, apoptosis, and autophagy. This study is aimed to identify the effect of DAPK2 on oxidative damage and apoptosis of placental cells in hypertensive disorder complicating pregnancy (HDCP) through mTOR pathway. Microarray-based gene expression analysis was performed to predict the differentially expressed genes related to HDCP. To investigate the specific mechanism of DAPK2 in HDCP cells, placental microvascular endothelial cells were treated with mimic or siRNA of DAPK2 and mTOR to detect the expression of related genes, cell autophagy and apoptosis and oxidative damage. Finally, rats were modeled with HDCP to verify the cell experiment results. DAPK2 was downregulated in HDCP, and could activate mTOR. Besides, DAPK2 overexpression led to decreases in autophagy in HPVECs as well as apoptosis and oxidative damage in placental cells indicated by a substantial decrease in Beclin-1, LC3 II/LC3 I and Bax along with an increase in Bcl-2, 4EBP1 and p70S6K. It also ameliorates blood pressure elevation in HDCP rats. The study defined remission effect of DAPK2 on placental cell oxidative damage and apoptosis in HDCP via mTOR activation. Together, DAPK2 regulating mTOR pathway presents a promising therapy for HDCP treatment.

Maternal supraphysiological hypercholesterolemia associates with endothelial dysfunction of the placental microvasculature

Maternal physiological or supraphysiological hypercholesterolemia (MPH, MSPH) occurs during pregnancy. MSPH is associated with foetal endothelial dysfunction and atherosclerosis. However, the potential effects of MSPH on placental microvasculature are unknown. The aim of this study was to determine whether MSPH alters endothelial function in the placental microvasculature both ex vivo in venules and arterioles from the placental villi and in vitro in primary cultures of placental microvascular endothelial cells (hPMEC). Total cholesterol < 280 mg/dL indicated MPH, and total cholesterol ≥280 mg/dL indicated MSPH. The maximal relaxation to histamine, calcitonin gene-related peptide and adenosine was reduced in MSPH venule and arteriole rings. In hPMEC from MSPH placentas, nitric oxide synthase (NOS) activity and L-arginine transport were reduced without changes in arginase activity or the protein levels of endothelial NOS (eNOS), human cationic amino acid 1 (hCAT-1), hCAT-2A/B or arginase II compared with hPMEC from MPH placentas. In addition, it was shown that adenosine acts as a vasodilator of the placental microvasculature and that NOS is active in hPMEC. We conclude that MSPH alters placental microvascular endothelial function via a NOS/L-arginine imbalance. This work also reinforces the concept that placental endothelial cells from the macro- and microvasculature respond differentially to the same pathological condition.

An advanced human in vitro co-culture model for translocation studies across the placental barrier

Although various drugs, environmental pollutants and nanoparticles (NP) can cross the human placental barrier and may harm the developing fetus, knowledge on predictive placental transfer rates and the underlying transport pathways is mostly lacking. Current available in vitro placental transfer models are often inappropriate for translocation studies of macromolecules or NPs and do not consider barrier function of placental endothelial cells (EC). Therefore, we developed a human placental in vitro co-culture transfer model with tight layers of trophoblasts (BeWo b30) and placental microvascular ECs (HPEC-A2) on a low-absorbing, 3 µm porous membrane. Translocation studies with four model substances and two polystyrene (PS) NPs across the individual and co-culture layers revealed that for most of these compounds, the trophoblast and the EC layer both demonstrate similar, but not additive, retention capacity. Only the paracellular marker Na-F was substantially more retained by the BeWo layer. Furthermore, simple shaking, which is often applied to mimic placental perfusion, did not alter translocation kinetics compared to static exposure. In conclusion, we developed a novel placental co-culture model, which provides predictive values for translocation of a broad variety of molecules and NPs and enables valuable mechanistic investigations on cell type-specific placental barrier function.

602: Expression and function of ATP-binding cassette and solute carrier family transporters in isolated human placental microvascular endothelial cells

To identify and characterize the expression and function of ABC and SLC transporter proteins in isolated human placental microvascular endothelial cells (HPMVEC). This study was performed at a single center utilizing placentas from non-laboring cesarean delivery patients. Isolation of HPMVEC was accomplished through collagenase digestion of the placenta followed by positive selection with CD31 microbeads. Cell purity was determined by immunofluorescence staining for UEA-1 lectin, a robust endothelial marker. Relative mRNA abundance of ABC and SLC transporters in HPMVEC (n=4) was measured by qrtPCR using validated primers present on RT2 Profiler PCR array. The mean delta cycle threshold (ΔCq) was calculated by the difference in threshold cycle between the target gene and reference gene (RPLP0) in each sample. Transporter protein expression in HPMVEC was confirmed by Western blot analysis using commercially available antibodies. The ABC efflux transporters P-gp and BCRP are active components of the placental barrier and play an important role in fetal protection. The functional activity of P-gp and BCRP was assessed by measuring the intracellular accumulation of calcein AM and Hoescht 33342, in the presence or absence of transporter specific inhibitors. We obtained a proportion of 90% lectin-positive HPMVEC which was considered to be of sufficient purity (Fig 1). Transcripts from multiple ABC and SLC transporters were present in HPMVEC (Fig 2). BCRP was expressed in placental syncytium and vascular endothelium, while P-gp was predominately localized to the syncytiotrophoblasts. However, P-gp functional activity was present in HPMVEC, which showed a 64% increase in Calcein AM accumulation after 60-minute incubation in the presence of a P-gp inhibitor Elacridar (p<0.05). There was no calculated difference in Hoechst 33342 accumulation in the presence of the BCRP selective blocker Ko143. HPMVEC line blood vessels of the villous tree, where they form the last line of defense to the fetal circulation. The expression and function of uptake and efflux transporter proteins in HPMVEC may be as important as their expression in syncytiotrophoblasts in regulating transplacental transport of drugs and xenobiotics.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Eleveted maternal lipid level increases cholesterol efflux to hdl in human trophoblast but not in placental microvascular endothelial cells

Eleveted maternal lipid level increases cholesterol efflux to hdl in human trophoblast but not in placental microvascular endothelial cells

Effect of MgSO4 on protein expression and exosomes release from human placental microvascular endothelial cells from late-onset preeclampsia

Effect of MgSO4 on protein expression and exosomes release from human placental microvascular endothelial cells from late-onset preeclampsia

Adenosine A2A receptor regulates expression of vascular endothelial growth factor in feto-placental endothelium from normal and late-onset pre-eclamptic pregnancies.

We aim to investigate whether A2A/nitric oxide-mediated regulation of vascular endothelial growth factor (VEGF) expression is impaired in feto-placental endothelial cells from late-onset pre-eclampsia. Cultures of human umbilical vein endothelial cells (HUVECs) and human placental microvascular endothelial cells (hPMECs) from normal and pre-eclamptic pregnancies were used. Assays by using small interference RNA (siRNA) for A2A were performed, and transfected cells were used for estimation of messenger RNA (mRNA) levels of VEGF, as well as for cell proliferation and angiogenesis in vitro. CGS-21680 (A2A agonist, 24h) increases HUVEC and hPMEC proliferation in a dose response manner. Furthermore, similar to CGS-21680, the nitric oxide donor, S-nitroso-N-acetyl-penicillamine oxide (SNAP), increased cell proliferation in a dose response manner (logEC50 10-9.2M). In hPMEC, CGS-21680 increased VEGF protein levels in both normal (∼1.5-fold) and pre-eclamptic pregnancies (∼1.2-fold), an effect blocked by the A2A antagonist, ZM-241385 (10-5M) and the inhibitor of NO synthase, N ω-nitro-L-arginine methyl ester hydrochloride (L-NAME). Subsequently, SNAP partially recovered cell proliferation and in vitro angiogenesis capacity of cells from normal pregnancies exposed to siRNA for A2A. CGS-21680 also increased (∼1.5-fold) the level of VEGF mRNA in HUVEC from normal pregnancies, but not in pre-eclampsia. Additionally, transfection with siRNA for A2A decrease (∼30%) the level of mRNA for VEGF in normal pregnancy compared to untransfected cells, an effect partially reversed by co-incubation with SNAP. The A2A-NO-VEGF pathway is present in endothelium from microcirculation and macrocirculation in both normal and pre-eclamptic pregnancies. However, NO signaling pathway seems to be impaired in HUVEC from pre-eclampsia.

86 MgSO4 modulates A2A and A2B adenosine receptors, eNOS and iNOS expression, and l -arginine transport in human placental microvascular endothelial cells

Control of vascular tone in the human placenta depends on locally-generated endothelium derived vasoactive molecules. Nitric oxide (NO) is a vasodilator that caused low impedance, high-blood flow circuit facilitating the transfer of oxygen and other nutrients to the developing fetus. Thus, molecules that regulate the synthesis or bioavailability of NO are determinant in this phenomenon. The cationic amino acid l -arginine is the substrate for NO synthases (NOS) and NOS activity seems dependent on the l -arginine transport at the plasma membrane in endothelial cells. The endogenous nucleoside adenosine activates l -arginine transport and NO synthesis in the foetoplacental endothelium via activation of A2A adenosine receptors (A2AAR) in normal pregnancies. Interestingly, maternal foetal plasma concentration of adenosine is increased in preeclampsia, a syndrome associated with reduced vascular reactivity and blood flow. Since magnesium (Mg2+) is required for A2AAR-dependent dilation of rat mesenteric vessels, a potential link between Mg2+ and adenosine receptors in the foetoplacental vasculature is likely. We hypothesize that human placental microvascular endothelial cells (hPMECs) show increased A2AR expression and l -arginine transport when exposed to MgSO4. Objective To evaluate the effect of MgSO4 on eNOS, iNOS, A2AAR, and A2BAR expression, and l -arginine transport in hPMECs. Methods Primary cultures of hPMECs was made under standard conditions (37 °C, 5% CO2) in medium 199 supplemented with 10% newborn and 10% foetal calf serum (passage 3). Cells were incubated (37 °C, 12 h) in the absence or presence of MgSO4 (1.5–4 mM). eNOS, iNOS, A2AAR, and A2BAR protein abundance was assayed by Western blot. Kinetics of l -arginine transport (0–1000 μ M, 3 μ Ci/mL l -[3H]arginine, 1 min, 37 °C) at initial rates was measured. Results Incubation of hPMECs with MgSO4 increased A2AAR (0.53 ± 0.02 fold, EC50 =;0.53 ± 0.24 mM) and iNOS (0.43 ± 0.03 fold, EC50 = 0.81 ± 0.28 mM) protein abundance. However, MgSO4 did not alter the protein abundance of eNOS or A2BAR. Equally, MgSO4 increased (1.7 ± 0.2 fold, EC50 = 2.1 ± 0.3 mM) the maximal transport capacity (Vmax/Km) of l -arginine. Conclusions MgSO4 activates endothelial function via a mechanism requiring A2AAR and iNOS resulting in higher l -arginine transport in hPMECs from normal pregnancies. This phenomenon could be relevant in the endothelial dysfunction seen in preeclampsia where patients are treated with MgSO4. Acknowledgements: Fondo Nacional de Desarrollo Cientifico y Tecnologico (FONDECYT 3160194/1150377/1150344/1150083), Chile. Direccion de Investigacion (2015-0032-I), Universidad San Sebastian, Chile. RS holds Comision Nacional de Investigacion y Desarrollo (CONICYT) PhD and Faculty of Medicine, PUC-PhD fellowships, Chile.

Inhibition of human placental endothelial cell proliferation and angiogenesis by netrin-4

IntroductionNetrin-4 is a secreted member of the laminin-related protein family, known to be involved in axonal guidance and endothelial cell survival, proliferation, and migration. We have recently reported the cellular localization of netrin-4 and its receptor neogenin in human first trimester and term placenta. A strong expression of netrin-4 was observed in trophoblast and in endothelial cells, suggesting a potential role of this protein in placental angiogenesis. In relation to human pregnancy, it has been reported that circulating netrin-4 were increased in fetal umbilical cord blood of intrauterine growth restriction IUGR compared to normal pregnancy suggesting an adverse effect of this protein on placental and fetal development.The aim of this study was to determine the role of netrin-4 in placental angiogenesis. MethodsThe effects of netrin-4 on proliferation, migration, tube-like organization, and spheroid sprouting of human placental microvascular endothelial cells (HPEC) were studied. ResultsWe demonstrated that netrin-4 inhibits HPEC proliferation, tube-like formation, migration and spheroid sprouting, suggesting a direct role of netrin-4 in the regulation of intra-villus angiogenesis. DiscussionThis is the first report of an anti-angiogenic activity of netrin-4 in human placenta. This study brings new insights into netrin-4 roles in placental angiogenesis and suggests possible involvements of netrin-4 in angiogenesis-related pathologies such as IUGR.

Altered decorin leads to disrupted endothelial cell function: A possible mechanism in the pathogenesis of fetal growth restriction?

ObjectiveFetal growth restriction (FGR) is a key cause of adverse pregnancy outcome where maternal and fetal factors are identified as contributing to this condition. Idiopathic FGR is associated with altered vascular endothelial cell functions. Decorin (DCN) has important roles in the regulation of endothelial cell functions in vascular environments. DCN expression is reduced in FGR. The objectives were to determine the functional consequences of reduced DCN in a human microvascular endothelial cell line model (HMVEC), and to determine downstream targets of DCN and their expression in primary placental microvascular endothelial cells (PLECs) from control and FGR-affected placentae. ApproachShort-interference RNA was used to reduce DCN expression in HMVECs and the effect on proliferation, angiogenesis and thrombin generation was determined. A Growth Factor PCR Array was used to identify downstream targets of DCN. The expression of target genes in control and FGR PLECs was performed. ResultsDCN reduction decreased proliferation and angiogenesis but increased thrombin generation with no effect on apoptosis. The array identified three targets of DCN: FGF17, IL18 and MSTN. Validation of target genes confirmed decreased expression of VEGFA, MMP9, EGFR1, IGFR1 and PLGF in HMVECs and PLECs from control and FGR pregnancies. ConclusionsReduction of DCN in vascular endothelial cells leads to disrupted cell functions. The targets of DCN include genes that play important roles in angiogenesis and cellular growth. Therefore, differential expression of these may contribute to the pathogenesis of FGR and disease states in other microvascular circulations.