Isolation and Culture of Arterial Smooth Muscle Cells From Human Placenta

Revealing the molecular landscape of human placenta: a systematic review and meta-analysis of single-cell RNA sequencing studies

BACKGROUND

With increasing significance of developmental programming effects associated with placental dysfunction, more investigations are devoted to improving the characterization and understanding of placental signatures in health and disease. The placenta is a transitory but dynamic organ adapting to the shifting demands of fetal development and available resources of the maternal supply throughout pregnancy. Trophoblasts (cytotrophoblasts, syncytiotrophoblasts, and extravillous trophoblasts) are placental-specific cell types responsible for the main placental exchanges and adaptations. Transcriptomic studies with single-cell resolution have led to advances in understanding the placenta's role in health and disease. These studies, however, often show discrepancies in characterization of the different placental cell types.

OBJECTIVE AND RATIONALE

We aim to review the knowledge regarding placental structure and function gained from the use of single-cell RNA sequencing (scRNAseq), followed by comparing cell-type-specific genes, highlighting their similarities and differences. Moreover, we intend to identify consensus marker genes for the various trophoblast cell types across studies. Finally, we will discuss the contributions and potential applications of scRNAseq in studying pregnancy-related diseases.

SEARCH METHODS

We conducted a comprehensive systematic literature review to identify different cell types and their functions at the human maternal-fetal interface, focusing on all original scRNAseq studies on placentas published before March 2023 and published reviews (total of 28 studies identified) using PubMed search. Our approach involved curating cell types and subtypes that had previously been defined using scRNAseq and comparing the genes used as markers or identified as potential new markers. Next, we reanalyzed expression matrices from the six available scRNAseq raw datasets with cell annotations (four from first trimester and two at term), using Wilcoxon rank-sum tests to compare gene expression among studies and annotate trophoblast cell markers in both first trimester and term placentas. Furthermore, we integrated scRNAseq raw data available from 18 healthy first trimester and nine term placentas, and performed clustering and differential gene expression analysis. We further compared markers obtained with the analysis of annotated and raw datasets with the literature to obtain a common signature gene list for major placental cell types.

OUTCOMES

Variations in the sampling site, gestational age, fetal sex, and subsequent sequencing and analysis methods were observed between the studies. Although their proportions varied, the three trophoblast types were consistently identified across all scRNAseq studies, unlike other non-trophoblast cell types. Notably, no marker genes were shared by all studies for any of the investigated cell types. Moreover, most of the newly defined markers in one study were not observed in other studies. These discrepancies were confirmed by our analysis on trophoblast cell types, where hundreds of potential marker genes were identified in each study but with little overlap across studies. From 35 461 and 23 378 cells of high quality in the first trimester and term placentas, respectively, we obtained major placental cell types, including perivascular cells that previously had not been identified in the first trimester. Importantly, our meta-analysis provides marker genes for major placental cell types based on our extensive curation.

WIDER IMPLICATIONS

This review and meta-analysis emphasizes the need for establishing a consensus for annotating placental cell types from scRNAseq data. The marker genes identified here can be deployed for defining human placental cell types, thereby facilitating and improving the reproducibility of trophoblast cell annotation.

Effects of Coronary Artery Disease-Associated Variants on Vascular Smooth Muscle Cells

BACKGROUND

Genome-wide association studies have identified many genetic loci that are robustly associated with coronary artery disease (CAD). However, the underlying biological mechanisms are still unknown for most of these loci, hindering the progress to medical translation. Evidence suggests that the genetic influence on CAD susceptibility may act partly through vascular smooth muscle cells (VSMCs).

METHODS

We undertook genotyping, RNA sequencing, and cell behavior assays on a large bank of VSMCs (n>1499). Expression quantitative trait locus and splicing quantitative trait locus analyses were performed to identify genes with an expression that was influenced by CAD-associated variants. To identify candidate causal genes for CAD, we ascertained colocalizations of VSMC expression quantitative trait locus signals with CAD association signals by performing causal variants identification in associated regions analysis and the summary data-based mendelian randomization test. Druggability analysis was then performed on the candidate causal genes. CAD risk variants were tested for associations with VSMC proliferation, migration, and apoptosis. Collective effects of multiple CAD-associated variants on VSMC behavior were estimated by polygenic scores.

RESULTS

Approximately 60% of the known CAD-associated variants showed statistically significant expression quantitative trait locus or splicing quantitative trait locus effects in VSMCs. Colocalization analyses identified 84 genes with expression quantitative trait locus signals that significantly colocalized with CAD association signals, identifying them as candidate causal genes. Druggability analysis indicated that 38 of the candidate causal genes were druggable, and 13 had evidence of drug-gene interactions. Of the CAD-associated variants tested, 139 showed suggestive associations with VSMC proliferation, migration, or apoptosis. A polygenic score model explained up to 5.94% of variation in several VSMC behavior parameters, consistent with polygenic influences on VSMC behavior.

CONCLUSIONS

This comprehensive analysis shows that a large percentage of CAD loci can modulate gene expression in VSMCs and influence VSMC behavior. Several candidate causal genes identified are likely to be druggable and thus represent potential therapeutic targets.

In vitro sepsis induces Nociceptin/Orphanin FQ receptor (NOP) expression in primary human vascular endothelial but not smooth muscle cells

Sepsis is a dysregulated host response to infection that can cause widespread effects on other organs including cardiovascular depression, hypotension and organ failure. The receptor for Nociceptin/Orphanin FQ (N/OFQ), NOP is expressed on immune cells and these cells can release the peptide. Exogenous N/OFQ can dilate blood vessels and this peptide is increased in animal and human sepsis. We hypothesise that NOP receptors are present on vascular endothelial cells and therefore provide the target for released N/OFQ to cause vasodilation and hence hypotension. Using human umbilical vein endothelial cells (HUVEC) and human vascular smooth muscle cells (HVSMC) freshly prepared from umbilical cords and up to passage 4, we assessed NOP mRNA expression by Polymerase Chain Reaction (PCR), NOP surface receptor expression using a fluorescent NOP selective probe (N/OFQ_ATTO594) and NOP receptor function with N/OFQ stimulated ERK1/2 phosphorylation. As an in vitro sepsis mimic we variably incubated cells with 100ng/ml Lipopolysaccharide and Peptidoglycan G (LPS/PepG). HUVECs express NOP mRNA and this was reduced by ~80% (n = 49) after 24–48 hours treatment with LPS/PepG. Untreated cells do not express surface NOP receptors but when treated with LPS/PepG the reduced mRNA was translated into protein visualised by N/OFQ_ATTO594 binding (n = 49). These NOP receptors in treated cells produced an N/OFQ (1μM) driven increase in ERK1/2 phosphorylation (n = 20). One (of 50) HUVEC lines expressed NOP mRNA and receptor protein in the absence of LPS/PepG treatment. In contrast, HVSMC expressed NOP mRNA and surface receptor protein (n = 10) independently of LPS/PepG treatment. These receptors were also coupled to ERK1/2 where N/OFQ (1μM) increased phosphorylation. Collectively these data show that an in vitro sepsis mimic (LPS/PepG) upregulates functional NOP expression in the vascular endothelium. Activation of these endothelial receptors as suggested from in vivo whole animal work may contribute to the hypotensive response seen in sepsis. Moreover, blockade of these receptors might be a useful adjunct in the treatment of sepsis.

Optic nerve head astrocytes contribute to vascular associated effects

Purpose

This study was conducted in order to test the expression of vasoactive substances within rat lamina cribrosa (LC) and optic nerve head (ONH) astrocytes, so as to investigate the role and potential mechanism of ONH astrocytes in vascular associated effects.

Methods

LC tissue sections and primary cultured ONH astrocytes were obtained from adult Sprague-Dawley (SD) rats. Immunofluorescent staining was then used to detect the expression of vasoactive substances. Hyperoxia exposure was carried out both in vivo and in vitro, after which nitric oxide (NO) levels in LC tissue and cell supernatant were detected. The variations of protein and gene expression associated with vasoactive substances were subsequently tested. ONH astrocytes and vascular smooth muscle cells (VSMCs) were then incubated in a direct co-culture manner. Morphological parameters of VSMCs were finally analyzed in order to evaluate cell contraction.

Results

Endothelin-1 (ET-1), nitric oxide synthase (NOS) and renin-angiotensin system (RAS) were detected in both LC tissue and ONH astrocytes. Retinal vessel diameter was found obviously decreased following hyperoxia exposure. Moreover, hyperoxia inhibited NO production both in vivo and in vitro. ET-1 and RAS elements were observed to be upregulated, whereas NOS was downregulated. In ONH astrocytes and VSMCs co-culture system, the length-to-width ratio of VSMCs was shown to significantly increase on days 3 and 7 in hyperoxia compared with normoxia.

Conclusions

There is an abundance of expression of vasoactive substances within LC tissue and ONH astrocytes. The contractile response of VSMCs in the co-culture system provided direct evidence for the involvement of ONH astrocytes in vascular associated effects, which may signify a potentially novel direction for future research.

Epigenetic Regulation of Interleukin-17-Related Genes and Their Potential Roles in Neutrophil Vascular Infiltration in Preeclampsia

DNA methylation is an epigenetic mechanism controlling gene expression, and reduced methylation is associated with increased gene expression. We hypothesized that IL-17 cytokines are regulated by DNA methylation, are elevated in the circulation of preeclamptic women, and stimulate vascular neutrophil chemokine expression, which could account for vascular infiltration of neutrophils in preeclampsia. We found significantly reduced DNA methylation of IL17A, IL17E, and IL17F genes in omental arteries of preeclamptic women, significantly reduced methylation of IL2, which regulates IL-17-producing T-lymphocytes, and significantly reduced methylation of genes encoding neutrophil chemokines and TNFα receptors related to lymphocyte function. Maternal plasma levels of IL-17A were significantly elevated in the second trimester of preeclamptic pregnancy as compared to normal pregnancy. To test if methylation regulates IL-17 cytokines, a lymphocyte cell line (Jurkat) was cultured with a hypomethylating agent. Hypomethylation increased expression of IL17E (aka IL25), IL17F, and IL2. IL17A was not expressed by Jurkat cells. To test the potential role of IL-17 cytokines in vascular neutrophil infiltration associated with preeclampsia, human vascular smooth muscle cells were cultured with IL-17 cytokines. IL-17A, but not IL-17E or IL-17F, increased gene expression of neutrophil chemokines (IL-8, CXCL5, and CXCL6) that are increased in vascular smooth muscle of preeclamptic women. The monocyte chemokine, CCL-2, was not increased. TNFα also increased neutrophil chemokines. IL-17 cytokines are regulated by DNA methylation; IL-17A is elevated in preeclampsia and stimulates expression of neutrophil chemokines in vascular smooth muscle. IL-17A could be responsible for vascular infiltration of neutrophils in preeclampsia.

Coxsackievirus and adenovirus receptor mediates the responses of endothelial cells to fluid shear stress

Endothelial mechanotransduction by fluid shear stress (FSS) modulates endothelial function and vascular pathophysiology through mechanosensors on the cell membrane. The coxsackievirus and adenovirus receptor (CAR) is not only a viral receptor but also a component of tight junctions and plays an important role in tissue homeostasis. Here, we demonstrate the expression, regulatory mechanism, and role of CAR in vascular endothelial cells (ECs) under FSS conditions. Disturbed flow increased, whereas unidirectional laminar shear stress (LSS) decreased, CAR expression in ECs through the Krüppel-like factor 2 (KLF2)/activator protein 1 (AP-1) axis. Deletion of CAR reduced the expression of proinflammatory genes and endothelial inflammation induced by disturbed flow via the suppression of NF-κB activation. Consistently, disturbed flow-induced atherosclerosis was reduced in EC-specific CAR KO mice. CAR was found to be involved in endothelial mechanotransduction through the regulation of platelet endothelial cell adhesion molecule 1 (PECAM-1) phosphorylation. Our results demonstrate that endothelial CAR is regulated by FSS and that this regulated CAR acts as an important modulator of endothelial mechanotransduction by FSS.

Research into the mechanisms by which blood flow disturbances affect the function of endothelial cells (ECs), the cells lining the interior of blood vessels, reveals potential new targets for treating atherosclerosis. Kihwan Kwon at Ewha Womans University in Seoul, South Korea, and colleagues found that a membrane protein, the coxsackie and adenovirus receptor, CAR, mediates the response of ECs to the shear stress exerted by blood flow. They showed, in human tissue and in mice, that CAR protein levels in ECs increase when they are exposed to low or oscillatory blood flow, which is linked to the build-up of plaque inside arteries. Lowering CAR levels in ECs reduced the expression of proinflammatory genes and the formation of atherosclerotic lesions in mice. These findings suggest that reducing CAR activity could be a promising approach for treating atherosclerosis.

[Pre-eclampsia prevention in 2018 in general population and in lupic women: At the dawn of a personalized medicine?]

Pre-eclampsia prevention represents a major public health issue, as this vasculo-placental disorder generates a great burden of foeto-maternal morbi-mortality. Aspirin has proved its efficacy in primary and secondary pre-eclampsia prevention, especially when it is given at 150mg per day bedtime before 15 weeks of gestation to high-risk women. In the English trial ASPRE, high-risk women were identified by an algorithm taking into account angiogenic biomarkers ascertained at the end of first trimester of pregnancy. This article focuses on physiopathological mechanisms and risk factors of pre-eclampsia and on the interest of early angiogenic biomarkers dosing during pregnancy, for the assessment of pre-eclampsia risk. Unlike Great Britain or Israel, cost-effectiveness of this algorithm in general population has not been assessed in France. Finally, systemic lupus erythematous is at high risk of vasculo-placental disorders. Although few studies of angiogenic biomarkers dosing during lupus pregnancies identified a correlation between high sFlt1 levels at the end of first trimester and subsequent onset of severe vasculo-placental disorders, with a very good negative predictive value of sFtl1. Angiogenic biomarkers ascertainment for screening of vasculo-placental disorders in pregnant women with systemic lupus erythematous could allow targeting at best women needing an aspirin treatment and a closer monitoring.

Novel regulations of the angiotensin II receptor type 1 by calmodulin

The angiotensin II receptor type 1 (AT₁R) mediates many Ca²⁺-dependent actions of angiotensin II (AngII). Calmodulin (CaM) is a key transducer of Ca²⁺ signals in cells. Two locations on the receptor's submembrane domains (SMD) 3 and 4 are known to interact with CaM. However, the binding sites for CaM, biochemical properties of the interactions, and their functional impact are not fully understood. Using a FRET-based screening method, we identified a new binding site for CaM on SMD2 (a.a. 125-141), in addition to SMD3 and the juxtamembranous region of SMD4 (SMD4_JM, a.a., 309-327). Simultaneous measurements of CaM binding and free Ca²⁺ show that the interactions are Ca²⁺-dependent, with disparate K_d and EC50(Ca²⁺) values within the physiological range of cytoplasmic Ca²⁺. Full interaction between CaM and SMD3 requires the entire domain (a.a. 215-242) and has an EC50(Ca²⁺) value in the range of resting cytoplasmic Ca²⁺, suggesting AT₁R-CaM interaction can occur in resting conditions in cells. AngII induces robust ERK1/2 phosphorylation in primary vascular smooth muscle cells. This effect is suppressed by AT₁R inhibitor losartan and virtually abolished by CaM antagonist W-7. AngII-induced ERK1/2 phosphorylation is suppressed in cells expressing mutant AT₁R with reduced CaM binding at each identified binding domain. AngII triggers transient Ca²⁺ signals in cells expressing wild-type AT₁R. These signals are reduced in cells expressing mutant AT₁R with reduced CaM binding at SMD3 or SMD4_JM, but are very slow-rising, low amplitude signal in cells expressing AT₁R with reduced CaM binding at SMD2. The data indicate that CaM interactions with AT₁R can occur at various domains, with different affinities, at different physiological Ca²⁺ levels, and are important for AT₁R-mediated signaling.

The biological impact of blood pressure-associated genetic variants in the natriuretic peptide receptor C gene on human vascular smooth muscle

Elevated blood pressure (BP) is a major global risk factor for cardiovascular disease. Genome-wide association studies have identified several genetic variants at the NPR3 locus associated with BP, but the functional impact of these variants remains to be determined. Here we confirmed, by a genome-wide association study within UK Biobank, the existence of two independent BP-related signals within NPR3 locus. Using human primary vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) from different individuals, we found that the BP-elevating alleles within one linkage disequilibrium block identified by the sentinel variant rs1173771 was associated with lower endogenous NPR3 mRNA and protein levels in VSMCs, together with reduced levels in open chromatin and nuclear protein binding. The BP-elevating alleles also increased VSMC proliferation, angiotensin II-induced calcium flux and cell contraction. However, an analogous genotype-dependent association was not observed in vascular ECs. Our study identifies novel, putative mechanisms for BP-associated variants at the NPR3 locus to elevate BP, further strengthening the case for targeting NPR-C as a therapeutic approach for hypertension and cardiovascular disease prevention.

TMEM16A regulates portal vein smooth muscle cell proliferation in portal hypertension

The aim of the present study was to elucidate the effect of transmembrane protein 16A (TMEM16A) on portal vein smooth muscle cell (PVSMC) proliferation associated with portal vein remodeling in portal hypertension (PHT). Sprague-Dawley rats were subjected to bile duct ligation to establish a rat model of liver cirrhosis and PHT. Sham-operated animals served as controls. At 8 weeks after bile duct ligation, the extent of liver fibrosis and the portal vein wall thickness were assessed using hematoxylin-eosin staining. The protein expression levels of TMEM16A, extracellular signal-regulated kinase 1 and 2 (ERK1/2) and phosphorylated ERK1/2 (p-ERK1/2) in the portal vein were detected by immunohistochemistry and western blotting. In vitro, the lentivirus vectors were constructed and transfected into PVSMCs to upregulate the expression of TMEM16A. Isolated rat primary PVSMCs were treated with a small molecule inhibitor of TMEM16A, T16A-inhA01. Cell cycle was detected by flow cytometry. The activity of TMEM16A in the portal vein isolated from bile duct ligated rats was decreased, while the expression level of p-ERK1/2 was increased. However, in vitro, upregulation of TMEM16A promoted the proliferation PVSMCs, while inhibition of TMEM16A channels inhibited the proliferation of PVSMCs. The results indicated that TMEM16A contributes to PVSMCs proliferation in vitro, but in vivo, it may be a negative regulator of cell proliferation influenced by numerous factors.

Expression of von Willebrand factor and caldesmon in the placental tissues of pregnancies complicated with intrauterine growth restriction

PURPOSE

The decreased placental perfusion is the underlying reason for intrauterine growth restriction that in turn leads to reduced placental perfusion and ischemia. However, there are several issues to be understood in the pathophysiology of intrauterine growth restriction. We aimed to study whether any compensatory response in placental vascular bed occur in pregnancies complicated with intrauterine growth restriction by the immunohistochemical staining of von Willebrand factor and caldesmon in placental tissues.

MATERIALS AND METHODS

A total of 103 pregnant women was enrolled in the study including 50 patients who were complicated with IUGR and 50 uncomplicated control patients. The study was designed in a prospective manner. All placentas were also stained with von Willebrand factor and caldesmon monoclonal kits.

RESULTS

The immunohistochemical staining of von Willebrand factor and caldesmon expressions in placental tissues were different between normal and intrauterine growth restriction group. The percentages of 2+ and 3+ von Willebrand factor expression were higher in the intrauterine growth restriction group comparing with the normal group, although the difference was not statistically significant. The intensity of caldesmon expression was significantly lower in the intrauterine growth restriction group in comparison with the normal group (p < .001).

CONCLUSION

Angiogenesis occurs as a placental response to intrauterine growth restriction which is a hypoxic condition. But newly formed vessels are immature and not strong enough. Our study is important to clarify the pathophysiology and placental compensatory responses in intrauterine growth restriction.

Increased NBCn1 expression, Na+/HCO3- co-transport and intracellular pH in human vascular smooth muscle cells with a risk allele for hypertension

Genome-wide association studies have revealed an association between variation at the SLC4A7 locus and blood pressure. SLC4A7 encodes the electroneutral Na+/HCO3- co-transporter NBCn1 which regulates intracellular pH (pHi). We conducted a functional study of variants at this locus in primary cultures of vascular smooth muscle and endothelial cells. In both cell types, we found genotype-dependent differences for rs13082711 in DNA-nuclear protein interactions, where the risk allele is associated with increased SLC4A7 expression level, NBCn1 availability and function as reflected in elevated steady-state pHi and accelerated recovery from intracellular acidosis. However, in the presence of Na+/H+ exchange activity, the SLC4A7 genotypic effect on net base uptake and steady-state pHi persisted only in vascular smooth muscle cells but not endothelial cells. We found no discernable effect of the missense polymorphism resulting in the amino acid substitution Glu326Lys. The finding of a genotypic influence on SLC4A7 expression and pHi regulation in vascular smooth muscle cells provides an insight into the molecular mechanism underlying the association of variation at the SLC4A7 locus with blood pressure.

Three-Dimensional Coculture Model to Analyze the Cross Talk Between Endothelial and Smooth Muscle Cells

The response of blood vessels to physiological and pathological stimuli partly depends on the cross talk between endothelial cells (EC) lining the luminal side and smooth muscle cells (SMC) building the inner part of the vascular wall. Thus, the in vitro analysis of the pathophysiology of blood vessels requires coculture systems of EC and SMC. We have developed and validated a modified three-dimensional sandwich coculture (3D SW-CC) of EC and SMC using open μ-Slides with a thin glass bottom allowing direct imaging. The culture dish comprises an intermediate plate to minimize the meniscus resulting in homogenous cell distribution. Human umbilical artery SMC were sandwiched between coatings of rat tail collagen I. Following SMC quiescence, human umbilical vein EC were seeded on top of SMC and cultivated until confluence. By day 7, EC had formed a confluent monolayer and continuous vascular endothelial (VE)-cadherin-positive cell/cell contacts. Below, spindle-shaped SMC had formed parallel bundles and showed increased calponin expression compared to day 1. EC and SMC were interspaced by a matrix consisting of laminin, collagen IV, and perlecan. Basal messenger RNA (mRNA) expression levels of E-selectin, angiopoietin-1, calponin, and intercellular adhesion molecule 1 (ICAM-1) of the 3D SW-CC was comparable to that of a freshly isolated mouse inferior vena cava. Addition of tumor necrosis factor alpha (TNF α) to the 3D SW-CC induced E-selectin and ICAM-1 mRNA and protein induction, comparable to the EC and SMC monolayers. In contrast, the addition of activated platelets induced a significantly delayed but more pronounced activation in the 3D SW-CC compared to EC and SMC monolayers. Thus, this 3D SW-CC permits analyzing the cross talk between EC and SMC that mediate cellular quiescence as well as the response to complex activation signals.

Linoleic Acid, but not Oleic Acid, Upregulates Production of Interleukin-8 by Human Vascular Smooth Muscle Cells via Arachidonic Acid Metabolites Under Conditions of Oxidative Stress

OBJECTIVE

Preeclampsia is associated with oxidative stress, elevated plasma levels of linoleic acid (LA), and increased vascular smooth muscle expression of the inflammatory chemokine, interleukin-8 (IL-8). We hypothesized that increased levels of LA under conditions of oxidative stress would increased production of IL-8 by vascular smooth muscle cells because LA is the dietary precursor to arachidonic acid (AA) and its metabolites that mediate inflammation. We also hypothesized that oleic acid (OA), which is not metabolized to AA metabolites, would not increase IL-8 under conditions of oxidative stress.

METHODS

To test this hypothesis, we cultured placental arterial smooth muscle (PASM) cells with an oxidizing solution enriched with LA (OxLA) or OA (OxOA). Media concentrations were analyzed for IL-8 and AA metabolites. Inhibitors were used to block the lipoxygenase and cyclooxygenase pathways.

RESULTS

Exposure of cells to OxLA, but not to OxOA, significantly increased production of IL-8. OxLA also significantly increased production of AA metabolites. Nordihydroguaiaretic acid, an inhibitor of the lipoxygenase pathway, blocked IL-8 and leukotriene B4 (LTB4) production induced by OxLA, whereas indomethacin, an inhibitor of the cyclooxygenase pathway, blocked IL-8, prostaglandin E2 (PGE2), and thromboxane B2 (TXB2) production. Reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated gene expression in PASM cells for representative lipoxygenase (LTB4) and cyclooxygenase (thromboxane) metabolite receptors.

CONCLUSION

PASM cells produced IL-8 in response to LA, but not OA, under conditions of oxidative stress. The IL-8 response was mediated by AA metabolites.

Activation of KV7 channels stimulates vasodilatation of human placental chorionic plate arteries

INTRODUCTION

Potassium (K(+)) channels are key regulators of vascular smooth muscle cell (VSMC) excitability. In systemic small arteries, Kv7 channel expression/activity has been noted and a role in vascular tone regulation demonstrated. We aimed to demonstrate functional Kv7 channels in human fetoplacental small arteries.

METHODS

Human placental chorionic plate arteries (CPAs) were obtained at term. CPA responses to Kv7 channel modulators was determined by wire myography. Presence of Kv7 channel mRNA (encoded by KCNQ1-5) and protein expression were assessed by RT-PCR and immunohistochemistry/immunofluorescence, respectively.

RESULTS

Kv7 channel blockade with linopirdine increased CPA basal tone and AVP-induced contraction. Pre-contracted CPAs (AVP; 80 mM K(+) depolarization solution) exhibited significant relaxation to flupirtine, retigabine, the acrylamide (S)-1, and (S) BMS-204352, differential activators of Kv7.1 - Kv7.5 channels. All CPAs assessed expressed KCNQ1 and KCNQ3-5 mRNA; KCNQ2 was expressed only in a subset of CPAs. Kv7 protein expression was confirmed in intact CPAs and isolated VSMCs.

DISCUSSION

Kv7 channels are present and active in fetoplacental vessels, contributing to vascular tone regulation in normal pregnancy. Targeting these channels may represent a therapeutic intervention in pregnancies complicated by increased vascular resistance.

Marker profile for the evaluation of human umbilical artery smooth muscle cell quality obtained by different isolation and culture methods

Even though umbilical cord arteries are a common source of vascular smooth muscle cells, the lack of reliable marker profiles have not facilitated the isolation of human umbilical artery smooth muscle cells (HUASMC). For accurate characterization of HUASMC and cells in their environment, the expression of smooth muscle and mesenchymal markers was analyzed in umbilical cord tissue sections. The resulting marker profile was then used to evaluate the quality of HUASMC isolation and culture methods. HUASMC and perivascular-Wharton's jelly stromal cells (pv-WJSC) showed positive staining for α-smooth muscle actin (α-SMA), smooth muscle myosin heavy chain (SM-MHC), desmin, vimentin and CD90. Anti-CD10 stained only pv-WJSC. Consequently, HUASMC could be characterized as α-SMA+ , SM-MHC+ , CD10- cells, which are additionally negative for endothelial markers (CD31 and CD34). Enzymatic isolation provided primary HUASMC batches with 90-99 % purity, yet, under standard culture conditions, contaminant CD10+ cells rapidly constituted more than 80 % of the total cell population. Contamination was mainly due to the poor adhesion of HUASMC to cell culture plates, regardless of the different protein coatings (fibronectin, collagen I or gelatin). HUASMC showed strong attachment and long-term viability only in 3D matrices. The explant isolation method achieved cultures with only 13-40 % purity with considerable contamination by CD10+ cells. CD10+ cells showed spindle-like morphology and up-regulated expression of α-SMA and SM-MHC upon culture in smooth muscle differentiation medium. Considering the high contamination risk of HUASMC cultures by CD10+ neighboring cells and their phenotypic similarities, precise characterization is mandatory to avoid misleading results.

The effect of pH and ion channel modulators on human placental arteries

Chorionic plate arteries (CPA) are located at the maternofetal interface where they are able to respond to local metabolic changes. Unlike many other types of vasculature, the placenta lacks nervous control and requires autoregulation for controlling blood flow. The placental circulation, which is of low-resistance, may become hypoxic easily leading to fetal acidosis and fetal distress however the role of the ion channels in these circumstances is not well-understood. Active potassium channel conductances that are subject to local physicochemical modulation may serve as pathways through which such signals are transduced. The aim of this study was to investigate the modulation of CPA by pH and the channels implicated in these responses using wire myography. CPA were isolated from healthy placentae and pre-contracted with U46619 before testing the effects of extracellular pH using 1 M lactic acid over the pH range 7.4 - 6.4 in the presence of a variety of ion channel modulators. A change from pH 7.4 to 7.2 produced a 29±3% (n = 9) relaxation of CPA which increased to 61±4% at the lowest pH of 6.4. In vessels isolated from placentae of women with pre-eclampsia (n = 6), pH responses were attenuated. L-methionine increased the relaxation to 67±7% (n = 6; p<0.001) at pH 6.4. Similarly the TASK 1/3 blocker zinc chloride (1 mM) gave a maximum relaxation of 72±5% (n = 8; p<0.01) which compared with the relaxation produced by the TREK-1 opener riluzole (75±5%; n = 6). Several other modulators induced no significant changes in vascular responses. Our study confirmed expression of several ion channel subtypes in CPA with our results indicating that extracellular pH within the physiological range has an important role in controlling vasodilatation in the human term placenta.

Identification of a cytotoxic form of dimeric interleukin-2 in murine tissues

Interleukin-2 (IL-2) is a multi-faceted cytokine, known for promoting proliferation, survival, and cell death depending on the cell type and state. For example, IL-2 facilitates cell death only in activated T cells when antigen and IL-2 are abundant. The availability of IL-2 clearly impacts this process. Our laboratory recently demonstrated that IL-2 is retained in blood vessels by heparan sulfate, and that biologically active IL-2 is released from vessel tissue by heparanase. We now demonstrate that heparanase digestion also releases a dimeric form of IL-2 that is highly cytotoxic to cells expressing the IL-2 receptor. These cells include "traditional" IL-2 receptor-bearing cells such as lymphocytes, as well as those less well known for IL-2 receptor expression, such as epithelial and smooth muscle cells. The morphologic changes and rapid cell death induced by dimeric IL-2 imply that cell death is mediated by disruption of membrane permeability and subsequent necrosis. These findings suggest that IL-2 has a direct and unexpectedly broad influence on cellular homeostatic mechanisms in both immune and non-immune systems.

Biosensor-based approach identifies four distinct calmodulin-binding domains in the G protein-coupled estrogen receptor 1

The G protein-coupled estrogen receptor 1 (GPER) has been demonstrated to participate in many cellular functions, but its regulatory inputs are not clearly understood. Here we describe a new approach that identifies GPER as a calmodulin-binding protein, locates interaction sites, and characterizes their binding properties. GPER coimmunoprecipitates with calmodulin in primary vascular smooth muscle cells under resting conditions, which is enhanced upon acute treatment with either specific ligands or a Ca(2+)-elevating agent. To confirm direct interaction and locate the calmodulin-binding domain(s), we designed a series of FRET biosensors that consist of enhanced cyan and yellow fluorescent proteins flanking each of GPER's submembrane domains (SMDs). Responses of these biosensors showed that all four submembrane domains directly bind calmodulin. Modifications of biosensor linker identified domains that display the strongest calmodulin-binding affinities and largest biosensor dynamics, including a.a. 83-93, 150-175, 242-259, 330-351, corresponding respectively to SMDs 1, 2, 3, and the juxta-membranous section of SMD4. These biosensors bind calmodulin in a strictly Ca(2+)-dependent fashion and with disparate affinities in the order SMD2>SMD4>SMD3>SMD1, apparent K d values being 0.44 ± 0.03, 1.40 ± 0.16, 8.01 ± 0.29, and 136.62 ± 6.56 µM, respectively. Interestingly, simultaneous determinations of biosensor responses and suitable Ca(2+) indicators identified separate Ca(2+) sensitivities for their interactions with calmodulin. SMD1-CaM complexes display a biphasic Ca(2+) response, representing two distinct species (SMD1 sp1 and SMD1 sp2) with drastically different Ca(2+) sensitivities. The Ca(2+) sensitivities of CaM-SMDs interactions follow the order SMD1sp1>SMD4>SMD2>SMD1sp2>SMD3, EC50(Ca(2+)) values being 0.13 ± 0.02, 0.75 ± 0.05, 2.38 ± 0.13, 3.71 ± 0.13, and 5.15 ± 0.25 µM, respectively. These data indicate that calmodulin may regulate GPER-dependent signaling at the receptor level through multiple interaction sites. FRET biosensors represent a simple method to identify unknown calmodulin-binding domains in G protein-coupled receptors and to quantitatively assess binding properties.

Polymer-based delivering of shRNA to rabbit aortic smooth muscle cells suppressed the expression of IGF-1R in vitro and in vivo

Restenosis is one of clinical limitations for vein graft in coronary bypass graft. It has been proved that signal pathway IGF-1 and its receptor (IGF-1R) activated by hemodynamic mechanical stretch are responsible for the vascular smooth muscle cells proliferation in vein graft neointima formation. Unfortunately, there is no routinely successful method to resolve this problem. Gene delivering to vein graft possesses great therapeutic potential to prevent neointima formation. Polymer is one kind of nanoparticles, which can activate the process of endocytosis of cells. In this study, we evaluated the transfection efficiency and therapeutic potential of polymer-based transfection of plasmids expressing GFP and shRNAs targeting IGF-1R (pGFPshIGF-1Rs) to smooth muscle cells and rabbit external jugular vein graft. Results showed that polymer-based transfection provided high efficiency of transgene expression in smooth muscle cells in vitro. In vitro, IGF-1R-specific shRNA transfected by polymer inhibited IGF-1R protein expression by 52 ± 3.6%, when compared with mock transfected cells. In vivo delivering efficiency of pGFPshIGF-1R plasmid into the rabbit external jugular vein graft was significantly high in the polymer-based transfection group, when compared with negative control group. In vivo, polymer-based transfection IGF-1R-specific shRNA efficiently inhibited the expression of IGF-1R protein by 77 ± 3.6%, 65.6 ± 4.9%, and 76.7 ± 4.3% at 24, 48, and 72 h, respectively, when compared with negative control group. Our findings indicated that polymer-based transfection may be a promising technique that allows the targeting of gene therapy for vein graft restenosis.

Clonality of smooth muscle and fibroblast cell populations isolated from human fibroid and myometrial tissues

Uterine fibroids are conventionally defined as clonally derived benign tumours from the proliferation of a single smooth muscle cell (SMC). We have previously identified fibroblast-like cells in fibroids, the presence of which raises the question as to whether all cells within the fibroid have the same clonal origin. The first aim of this study was to develop a fluorescence-activated cell sorting (FACS)-based method to isolate different cell types from human myometrium and fibroid tissues. Secondly, we aimed to use X chromosome inactivation analysis to determine the clonality of cell subpopulations isolated from myometrial and fibroid tissues. Human myometrium and fibroid tissues were collected from women undergoing hysterectomy. Immunohistochemistry (IHC) and flow cytometry confirmed that in addition to SMCs, fibroblasts constitute a significant proportion of cells in human myometrium and fibroid tissues. FACS based on CD90 and ALDH1 reliably separated cells into three myometrial and four fibroid subpopulations: SMCs, vascular smooth muscle cells and two fibroblast subsets. Clonality was first determined by X chromosome inactivation using the classic DNA methylation-sensitive HUMARA assay. Data from this assay were highly variable, with only a quarter of samples meeting the definition of clonal fibroid and non-clonal myometrium. However, using an RNA-based X chromosome inactivation HUMARA assay, we were able to demonstrate clonality of all cellular constituents of most fibroids. Our results confirm that most fibroids are derived from a single cell, and for the first time demonstrates that these clonal cells differentiate into fibroblast and SMC subpopulation as the fibroid grows.

Isolation and culture of smooth muscle cells from human acute type A aortic dissection

BACKGROUND

Acute type A aortic dissection (TAAD) is a life-threatening vascular disease. Smooth muscle cells (SMCs) are the main composition of aortic media and dysfunction of SMCs may lead to acute TAAD. The aim of this work was to investigate whether the SMCs of acute TAAD could be isolated and cultured for further research.

METHODS

TAAD tissues were obtained from acute TAAD patients who underwent emergent surgical treatment. A simple and economical technique of collagenase digestion method was used to isolate and culture human SMCs. Confocal laser scanning microscopy was applied to identify SMC phenotypes. Purity of isolated and cultured SMCs was analyzed with flow cytometry and fluorescence microscopy respectively.

RESULTS

The purity of isolated SMCs was 78.2%, including α-smooth muscle cell actin positive 13.9%, calponin positive 35.0% and double positive 29.3%. For cultured SMCs, abundant expression of α-smooth muscle cell actin was observed universally under fluorescence microscope. Confocal laser scanning microscope testified that cultured cells were double positive of α-smooth muscle actin and calponin.

CONCLUSIONS

This is the first report of successful culture of SMCs isolated from human acute TAAD tissues. Living human SMCs of acute TAAD provides us with a new method for studying formation of acute TAAD.

STAT1 activation by venous malformations mutant Tie2-R849W antagonizes VEGF-A-mediated angiogenic response partly via reduced bFGF production

A missense mutation from arginine to tryptophan at residue 849 in the kinase domain of Tie2 (Tie2-R849W) is commonly identified in familial venous malformations. The mechanistic action of Tie2-R849W variant expression on angiogenic cascades including smooth muscle cell recruitment, however, remains elusive. To avoid confounding factors from endogenous Tie2 expression, Tie2-depleted endothelial cells (ECs) were used to study the effects of ectopic shRNA-resistant Tie2 variant expression, Tie2-WT* and Tie2-R849W*, on vascular cell proliferation, migration, tube formation, and smooth muscle cell (SMC) recruitment. Tie2-R849W* induced STAT1 phosphorylation at Tyr701. Tie2-R849W*-expressing cells had reduced ability to migrate and form tubes on Matrigel than their wildtype counterparts. STAT1 phosphorylation attenuated VEGF-A-induced STAT3 tyrosine phosphorylation in Tie2-R849W*-expressing HUVECs. The induced STAT1 activation also decreased VEGF-A-induced bFGF mRNA expression by competing with activated STAT3 for a direct binding to the consensus STAT-binding site at positions -997 to -989 bp from transcription start site in the bFGF promoter. Depleting STAT1 expression rescued the inability of Tie2-R849W expression to mediate angiogenesis. Moreover, bFGF neutralization or constitutive STAT1 activation, reminiscence of Tie2-R849W* expression, suppressed the smooth muscle cell recruiting ability of endothelial conditioned medium. This work reveals an anti-angiogenic role of STAT1 activation that acts in Tie2-R849W-expressing ECs to impair VEGF-A-mediated STAT3 signaling, bFGF production, and smooth muscle cell recruitment. A balancing activity of STAT1 and STAT3 may be important for Tie2-mediated vascular homeostasis.

Preeclampsia is associated with alterations in DNA methylation of genes involved in collagen metabolism

Maternal vascular dysfunction is a hallmark of preeclampsia. A recently described vascular phenotype of preeclampsia involves increased expression of matrix metalloproteinase-1 (MMP-1) in endothelial cells, vascular smooth muscle, and infiltrating neutrophils. In contrast, the expression of tissue inhibitor of metalloproteinases-1 (TIMP-1) and collagen type Iα 1 is either reduced or not changed in the vessels, suggesting an imbalance in vessel collagen degradation and synthesis in preeclampsia. In the present study, we explored the possible contribution of DNA methylation to the altered expression of genes involved in collagen metabolism. We assayed the differences in DNA methylation in omental arteries from normal pregnant and preeclamptic women, and determined whether reduced DNA methylation increases the expression of MMP-1 in cultured vascular smooth muscle cells and a neutrophil-like cell line, HL-60. Several MMP genes, including MMP1 and MMP8, were significantly less methylated in preeclamptic omental arteries, whereas TIMP and COL genes either were significantly more methylated or had no significant change in their DNA methylation status compared with normal pregnancy. Experimentally induced DNA hypomethylation increased MMP-1 expression in cultured vascular smooth muscle cells and MMP-1 cells. Our findings suggest that epigenetic regulation contributes to the imbalance in genes involved in collagen metabolism in blood vessels of preeclamptic women.

Smooth muscle cells isolated from thoracic aortic aneurysms exhibit increased genomic damage, but similar tendency for apoptosis

Aortic aneurysms (AA) are characterized by structural deterioration leading to progressive dilation. During the development of AA, two key structural changes are pronounced, one being degradation of extracellular matrix and the other loss of smooth muscle cells (SMCs) through apoptosis. Reactive oxygen species (ROS) are produced above physiological levels in dilated (aneurismal) part of the aorta compared to the nondilated part and they are known to be associated with both the extracellular matrix degradation and the loss of SMCs. In this study, we hypothesized that aneurismal SMCs are more prone to apoptosis and that at least some cells undergo apoptosis due to elevated ROS in the aortic wall. To test this hypothesis, we first isolated SMCs from thoracic aneurismal tissue and compared their apoptotic tendency with normal SMCs in response to H(2)O(2), oxidized sterol, or UV treatment. Exposed cells exhibited morphological changes characteristic of apoptosis, such as cell shrinkage, membrane blebbing, chromatin condensation, and DNA fragmentation. Terminal deoxynucleotidyl transferased UTP nick end labeling (TUNEL) further confirmed the fragmentation of nuclear DNA in these cells. Vascular SMCs were analyzed for their micronuclei (MN) and binucleate (BN) frequency as indicators of genomic abnormality. These data were then compared to patient parameters, including age, gender, hypertension, or aortic diameter for existing correlations. While the tendency for apoptosis was not significantly different compared to normal cells, both the %MN and %BN were higher in aneurismal SMCs. The data suggest that there is increased DNA damage in TAA samples, which might play a pivotal role in disease development.

Vascular smooth muscle cells remodel collagen matrices by long-distance action and anisotropic interaction

While matrix remodeling plays a key role in vascular physiology and pathology, the underlying mechanisms have remained incompletely understood. We studied the remodeling of collagen matrices by individual vascular smooth muscle cells (SMCs), clusters and monolayers. In addition, we focused on the contribution of transglutaminase 2 (TG2), which plays an important role in the remodeling of small arteries. Single SMCs displaced fibers in collagen matrices at distances up to at least 300 μm in the course of 8–12 h. This process involved both ‘hauling up’ of matrix by the cells and local matrix compaction at a distance from the cells, up to 200 μm. This exceeded the distance over which cellular protrusions were active, implicating the involvement of secreted enzymes such as TG2. SMC isolated from TG2 KO mice still showed compaction, with changed dynamics and relaxation. The TG active site inhibitor L682777 blocked local compaction by wild type cells, strongly reducing the displacement of matrix towards the cells. At increasing cell density, cells cooperated to establish compaction. In a ring-shaped collagen matrix, this resulted in preferential displacement in the radial direction, perpendicular to the cellular long axis. This process was unaffected by inhibition of TG2 cross-linking. These results show that SMCs are capable of matrix remodeling by prolonged, gradual compaction along their short axis. This process could add to the 3D organization and remodeling of blood vessels based on the orientation and contraction of SMCs.

Human vascular endothelial cells reduce sphingosylphosphorylcholine-induced smooth muscle cell contraction in co-culture system through integrin β4 and Fyn

AIM

In vascular strips, the adjacent endothelial cells modulate the contraction of vascular smooth muscle cells (VSMCs) induced by sphingosylphosphorylcholine (SPC) through nitric oxide (NO). The aim of this study was to elucidate the mechanisms by which vascular endothelial cells (VECs) reduce the SPC-induced contraction of VSMCs in a co-culture system.

METHODS

Human umbilical VECs and VSMCs were co-cultured. The VECs were transfected with integrin β4- or Fyn-specific siRNA. The areas of VSMCs that are involved in cell contractility were quantified using the Leica confocal software and collagen contractility assay. The production of NO in VECs was measured in the cell supernatants using NO Detection Kit. The levels of integrin β4 and Fyn in VECs and the levels of Rho kinase (ROCK) in VSMC were detected using immunofluorescence assays or Western blots.

RESULTS

Co-culture with VECs reduced the contraction of VSMCs induced by SPC (30 μmol/L). The down-regulation of integrin β4 or Fyn in VECs by the specific siRNA (20 nmol/L) was able to counteract the effects of VECs on the SPC-induced VSMC contractions. Furthermore, the integrin β4-specific siRNA (20 and 40 nmol/L) significantly reduced the level of Fyn protein and the production of NO in VECs, while increased the level of ROCK in VSMCs that had been stimulated by SPC.

CONCLUSION

The VECs reduced the SPC-induced contraction of VSMCs in the co-culture system through integrin β4 and Fyn proteins. In this process, NO may be the factor downstream of integrin β4 in VECs, while ROCK may be the key protein regulating the contraction of VSMCs.

Increased expression of matrix metalloproteinase-1 in systemic vessels of preeclamptic women: a critical mediator of vascular dysfunction

This study was conducted to determine the following: (1) whether matrix metalloproteinase-1 (MMP-1) is increased in systemic vessels of preeclamptic women, (2) whether this increase might be mediated by neutrophils, and (3) whether MMP-1 could be responsible for vascular dysfunction. Omental arteries and plasma were collected from healthy pregnant and preeclamptic women. Omental arteries were evaluated for gene and protein expression of MMP-1, collagen type 1α, tissue inhibitor of metalloproteinase-1, and vascular reactivity to MMP-1. Gene and protein expression levels were also evaluated in human vascular smooth muscle cells (VSMCs) co-cultured with activated neutrophils, reactive oxygen species, or tumor necrosis factor α. Vessel expression of MMP-1 and circulating MMP-1 levels were increased in preeclamptic women, whereas vascular expression of collagen or tissue inhibitor of metalloproteinase-1 were down-regulated or unchanged. In cultured VSMCs, the imbalance in collagen-regulating genes of preeclamptic vessels was reproduced by treatment with neutrophils, tumor necrosis factor α, or reactive oxygen species. Chemotaxis studies with cultured cells revealed that MMP-1 promoted recruitment of neutrophils via vascular smooth muscle release of interleukin-8. Furthermore, MMP-1 induced vasoconstriction via protease-activated receptor-1, whose expression was significantly increased in omental arteries of preeclamptic women and in VSMCs co-cultured with neutrophils. Collectively, these findings disclose a novel role for MMP-1 as a mediator of vasoconstriction and vascular dysfunction in preeclampsia.

PKC plays an important mediated effect in arginine vasopressin induced restoration of vascular responsiveness and calcium sensitization following hemorrhagic shock in rats

The present study investigated the mediated effect of protein kinase C (PKC) in arginine vasopressin (AVP)-induced restoration of vascular responsiveness and calcium sensitization following hemorrhagic shock. Using both isolated superior mesenteric artery from hemorrhagic shock rats and hypoxia-treated vascular smooth muscle cell (VSMC), we investigated the roles of PKC-alpha, delta and epsilon isoforms in AVP-induced restoration of vascular reactivity and calcium sensitivity. Meanwhile, effects of their specific inhibitors on the activity of myosin light chain phosphatase (MLCP), myosin light chain kinase (MLCK), and the phosphorylation of myosin light chain (MLC(20)) in VSMC were observed. The results indicated that AVP improved the reactivity of superior mesenteric artery and VSMC to norepinephrine and calcium following hemorrhagic shock and hypoxia. PKC-alpha inhibitor and PKC-epsilon inhibitory peptide antagonized these effects of AVP, while PKC-delta inhibitor only partially antagonized these effects of AVP. AVP up-regulated the expression of PKC-alpha and epsilon in the particulate fractions of hypoxia-treated VSMC with the decrease of the activity of MLCP and the increase of the phosphorylation of MLC(20). These effects of AVP were inhibited by PKC-alpha inhibitor and PKC-epsilon inhibitory peptide, but not by the PKC-delta inhibitor. The results suggested that PKC plays an important role in AVP-induced restoration of vascular reactivity and calcium sensitivity following hemorrhagic shock. PKC-alpha and epsilon may be the main isoforms involved in this process and play effect via MLC(20) phosphorylation dependent mechanism, while PKC-delta may be partially involved in AVP action by other mechanisms.

CD90 Expression on human primary cells and elimination of contaminating fibroblasts from cell cultures

Cluster Differentiation 90 (CD90) is a cell surface glycoprotein originally identified on mouse thymocytes. Although CD90 has been identified on a variety of stem cells and at varying levels in non-lymphoid tissues such as on fibroblasts, brain cells, and activated endothelial cells, the knowledge about the levels of CD90 expression on different cell types, including human primary cells, is limited. The goal of this study was to identify CD90 as a human primary cell biomarker and to develop an efficient and reliable method for eliminating unwanted or contaminating fibroblasts from human primary cell cultures suitable for research pursuant to cell based therapy technologies.

Isolation and culture of human umbilical artery smooth muscle cells expressing functional calcium channels

The human umbilical cord is a biological sample that can be easily obtained just after birth. A methodology was developed to perform cultures of human umbilical artery smooth muscle cells (HUASMC) expressing contractile proteins and functional ionic channels. To avoid fibroblast and endothelial cell contamination, we mechanically separated the tunica media, which only contains HUASMC and matrix proteins. To isolate the cells, collagenase V and elastase were used as hydrolyzing enzymes. The isolated cells were plated in collagen-coated dishes to obtain cultures of HUASMC. The cells obtained after different passages (1 to 6) exhibit the characteristic vascular smooth cell morphology and express smooth muscle alpha-2 actin, myosin heavy chain SM1, and alpha subunits of L- and T-type calcium channels (Cav 1.2, Cav 1.2, and Cav 3.2). Electrophysiology recordings for L- and T-type calcium channels were made, indicating that these channels are functional in the cultured cells. In conclusion, the procedure developed allows obtaining cultures of HUASMC expressing contractile proteins and also functional ionic channels. These cells could be used to study cellular and molecular aspects about the regulation of the vascular function.

A novel butyrolactone derivative inhibited smooth muscle cell migration and proliferation and maintained endothelial cell functions through selectively affecting Na, K-ATPase activity and mitochondria membrane potential during in vitro angiogenesis

We have found that 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran -2(3H)-one (3BDO), could effectively suppress human umbilical vascular endothelial cell (HUVEC) apoptosis induced by deprivation of fibroblast growth factor-2 and serum. Here, our purpose was to investigate whether 3BDO could modulate angiogenesis and its possible acting mechanism. The effect of 3BDO on angiogenesis was investigated by capillary-like tubule formation and rat aortic ring assay. Proliferation and migration of cells were detected by counting living cell number and scraping cell monolayer, respectively. Na, K-ATPase activity was measured spectrophotometrically. Mitochondrial membrane potential was analyzed using tetramethylrhodamine methylester fluorescence by confocal microscopy. Our results showed that 3BDO inhibited migration and proliferation of vascular smooth muscle cells (VSMCs), but maintained migration and tubule formation of HUVECs. In HUVECs, 3BDO inhibited Na, K-ATPase activity, but had no effect on mitochondria membrane potential. In VSMCs, it did not affect Na, K-ATPase activity, but depressed mitochondria membrane potential obviously. The data showed that 3BDO had selective effects on HUVECs and VSMCs, it might perform its role through the selective effects on the activity of Na, K-ATPase and the mitochondria membrane potential in HUVECs and VSMCs.

Caldesmon is necessary for maintaining the actin and intermediate filaments in cultured bladder smooth muscle cells

Caldesmon (CaD), a component of microfilaments in all cells and thin filaments in smooth muscle cells, is known to bind to actin, tropomyosin, calmodulin, and myosin and to inhibit actin-activated ATP hydrolysis by smooth muscle myosin. Thus, it is believed to regulate smooth muscle contraction, cell motility and the cytoskeletal structure. Using bladder smooth muscle cell cultures and RNA interference (RNAi) technique, we show that the organization of actin into microfilaments in the cytoskeleton is diminished by siRNA-mediated CaD silencing. CaD silencing significantly decreased the amount of polymerized actin (F-actin), but the expression of actin was not altered. Additionally, we find that CaD is associated with 10 nm intermediate-sized filaments (IF) and in vitro binding assay reveals that it binds to vimentin and desmin proteins. Assembly of vimentin and desmin into IF is also affected by CaD silencing, although their expression is not significantly altered when CaD is silenced. Electronmicroscopic analyses of the siRNA-treated cells showed the presence of myosin filaments and a few surrounding actin filaments, but the distribution of microfilament bundles was sparse. Interestingly, the decrease in CaD expression had no effect on tubulin expression and distribution of microtubules in these cells. These results demonstrate that CaD is necessary for the maintenance of actin microfilaments and intermediate-sized filaments in the cytoskeletal structure. This finding raises the possibility that the cytoskeletal structure in smooth muscle is affected when CaD expression is altered, as in smooth muscle de-differentiation and hypertrophy seen in certain pathological conditions.

Experimental methods to study human transplacental exposure to genotoxic agents

Human placenta differs more than any other organ between species. This is the primary reason to develop models utilizing human tissue to study placental functions. There are no major ethical restrictions using human placenta for scientific studies. Also, the size of human placenta enables a great number of different parameters to be studied in one placenta. The most important cell types considering transplacental transfer, are the trophoblasts differentiating into syncytiotrophoblasts facing maternal circulation, and endothelial cells of fetal vessels. Primary trophoblasts are difficult to culture and do not grow in monolayer thus inhibiting studies on the polarized functions of transport. Several cell lines originating from trophoblasts have been developed, of which BeWo cells seem most useful for transport studies, because they grow in a tight monolayer. Placental tissue can also be retained as explant cultures, although the trophoblast viability is very restricted despite of culture conditions. Cotyledons of human placenta can be retained viable in an isolated organ perfusion. Perfused placental tissue stays viable longer than placental tissue in tissue culture. Although human placental perfusion is the most tedious experimental method to study placental functions, there are several good reasons to develop it further: transplacental transfer and molecular mechanisms of genotoxic compounds can be studied. Placental perfusion is the only experimental method that retains fully the structure of placenta for polarized transport. Furthermore, perfusion of placentas from mothers, who smoke, use illegal drugs or have a disease, allows studies on the impact of such factors on fetal exposure to genotoxic agents.

Bile duct ligation induced acute inflammation up-regulates cyclooxygenase-2 content and PGE2 release in guinea pig gallbladder smooth muscle cell cultures

INTRODUCTION

This study examines hypotheses that BDL induces increased guinea pig gallbladder smooth muscle PGE2 release by up-regulation of COX-2.

METHODS

BDL, Sham and Control Hartley guinea pig gallbladders were placed in cell culture, grown to confluence and underwent Western Blot analysis for smooth muscle cell content of COX-1, COX-2, Prostacylin Synthase, actin, caldesmon, vinculin, meta-vinculin and tropomyosin and were assayed for basal release of 6-keto-PGF(1alpha), PGE2 and TxB2 by EIA.

RESULTS

BDL did not alter content of smooth muscle cytoskeletal proteins. BDL for 48 h increased smooth muscle cell release of PGE2 and 6-keto-PGF(1alpha) by 3-fold or more when compared to the Control and Sham groups. Western Blot analysis showed increased content of COX-2 in the BDL group.

CONCLUSIONS

BDL for 48 h markedly increased endogenous guinea pig smooth muscle cell PG release, which was due to increased COX-2 synthesis.