Serum-dependent effects of IGF-I and insulin on proliferation and invasion of human first trimester trophoblast cell models

Utility of In Vivo Magnetic Resonance Imaging Is Predictive of Gestational Diabetes Mellitus During Early Pregnancy

CONTEXT

Gestational diabetes (GDM) imposes long-term adverse health effects on the mother and fetus. The role of magnetic resonance imaging (MRI) during early gestation in GDM has not been well-studied.

OBJECTIVE

To investigate the role of quantitative MRI measurements of placental volume and perfusion, with distribution of maternal adiposity, during early gestation in GDM.

METHODS

At UCLA outpatient antenatal obstetrics clinics, ∼200 pregnant women recruited in the first trimester were followed temporally through pregnancy until parturition. Two placental MRI scans were prospectively performed at 14 to 16 weeks and 19 to 24 weeks gestational age (GA). Placental volume and blood flow (PBF) were calculated from placental regions of interest; maternal adiposity distribution was assessed by subcutaneous fat area ratio (SFAR) and visceral fat area ratio (VFAR). Statistical comparisons were performed using the two-tailed t test. Predictive logistic regression modeling was evaluated by area under the curve (AUC).

RESULTS

Of a total 186 subjects, 21 subjects (11.3%) developed GDM. VFAR was higher in GDM vs the control group, at both time points (P < 0.001 each). Placental volume was greater in GDM vs the control group at 19 to 24 weeks GA (P = 0.01). Combining VFAR, placental volume and perfusion, improved the AUC to 0.83 at 14 to 16 weeks (positive predictive value [PPV] = 0.77, negative predictive value [NPV] = 0.83), and 0.81 at 19 to 24 weeks GA (PPV = 0.73, NPV = 0.86).

CONCLUSION

A combination of MRI-based placental volume, perfusion, and visceral adiposity during early pregnancy demonstrates significant changes in GDM and provides a proof of concept for predicting the subsequent development of GDM.

Micro-RNAs in Human Placenta: Tiny Molecules, Immense Power

Micro-RNAs (miRNAs) are short non-coding single-stranded RNAs that modulate the expression of various target genes after transcription. The expression and distribution of kinds of miRNAs have been characterized in human placenta during different gestational stages. The identified miRNAs are recognized as key mediators in the regulation of placental development and in the maintenance of human pregnancy. Aberrant expression of miRNAs is associated with compromised pregnancies in humans, and dysregulation of those miRNAs contributes to the occurrence and development of related diseases during pregnancy, such as pre-eclampsia (PE), fetal growth restriction (FGR), gestational diabetes mellitus (GDM), recurrent miscarriage, preterm birth (PTB) and small-for-gestational-age (SGA). Thus, having a better understanding of the expression and functions of miRNAs in human placenta during pregnancy and thereby developing novel drugs targeting the miRNAs could be a potentially promising method in the prevention and treatment of relevant diseases in future. Here, we summarize the current knowledge of the expression pattern and function regulation of miRNAs in human placental development and related diseases.

Placental Endocrine Activity: Adaptation and Disruption of Maternal Glucose Metabolism in Pregnancy and the Influence of Fetal Sex

The placenta is an endocrine fetal organ, which secretes a plethora of steroid- and proteo-hormones, metabolic proteins, growth factors, and cytokines in order to adapt maternal physiology to pregnancy. Central to the growth of the fetus is the supply with nutrients, foremost with glucose. Therefore, during pregnancy, maternal insulin resistance arises, which elevates maternal blood glucose levels, and consequently ensures an adequate glucose supply for the developing fetus. At the same time, maternal β-cell mass and function increase to compensate for the higher insulin demand. These adaptations are also regulated by the endocrine function of the placenta. Excessive insulin resistance or the inability to increase insulin production accordingly disrupts physiological modulation of pregnancy mediated glucose metabolism and may cause maternal gestational diabetes (GDM). A growing body of evidence suggests that this adaptation of maternal glucose metabolism differs between pregnancies carrying a girl vs. pregnancies carrying a boy. Moreover, the risk of developing GDM differs depending on the sex of the fetus. Sex differences in placenta derived hormones and bioactive proteins, which adapt and modulate maternal glucose metabolism, are likely to contribute to this sexual dimorphism. This review provides an overview on the adaptation and maladaptation of maternal glucose metabolism by placenta-derived factors, and highlights sex differences in this regulatory network.

Nutritional and developmental programming effects of insulin

The discovery of insulin in 1921 was a major breakthrough in medicine and for therapy in patients with diabetes. The dramatic rise in the prevalence of overweight and obesity has been tightly linked to an increased prevalence of gestational diabetes mellitus (GDM), which poses major health concerns. Babies born to GDM mothers are more likely to develop obesity, type 2 diabetes and cardiovascular disease later in life. Evidence accumulated during the past two decades has revealed that high levels insulin, such as those observed during GDM, can have a widespread effect on the development and function of a variety of organs. This review summarises our current knowledge on the role of insulin in the placenta, cardiovascular system and brain during critical periods of development, as well as how it can contribute to lifelong metabolic regulation. We also discuss possible intervention strategies to ameliorate and hopefully reverse the developmental defects associated with obesity and GDM.

L-carnitine increases cell proliferation and amino acid transporter expression via the activation of insulin-like growth factor I signaling pathway in rat trophoblast cells

Early embryo implantation and development is primarily determined by the homeostasis between cellular apoptosis and proliferation as well as placental nutrient transporters. Recent studies showed that L-carnitine enhances female reproductive performance. However, the potential function of L-carnitine on placenta is largely unknown. In our study, primary rat trophoblast cells were separated and cultured for 12 hr in medium containing various concentrations of L-carnitine (0, 1, 10, and 50 mM). Placenta trophoblast cells treated with 50 mM L-carnitine increased the proportion of cells in S phase of the cell cycle (p < .05). In addition, live cell percentage was increased when treated with either 10 mM or 50 mM L-carnitine, which was accompanied with decreased necrotic cells, late apoptotic cells, and early apoptotic cells (p < .05). Compared with the control treatment, the mRNA expression of insulin-like growth factor I (IGF-1) and insulin-like growth factor I receptor (IGF-1R) was higher in rat placenta trophoblasts treated with either 10 mM or 50 mM L-carnitine (p < .05). Similarly, sodium-dependent neutral amino acid transporter (SNAT)-1 and SNAT2 were up-regulated in both mRNA and protein levels when trophoblast cells were treated with 50 mM L-carnitine (p < .05). Inhibiting downstream targets (Akt or ERK signaling pathways) of IGF-1 signaling pathway partially blocked the effect the L-carnitine-induced increase in protein abundances of SNAT1 and SNAT2. Collectively, our data showed protective role of L-carnitine on placenta trophoblast cells through the involvement of IGF-1 signaling pathway.

Transcriptomic profiling of trophoblast fusion using BeWo and JEG-3 cell lines

In human placenta, alteration in trophoblast differentiation has a major impact on placental maintenance and integrity. However, little is known about the mechanisms that control cytotrophoblast fusion. The BeWo cell line is used to study placental function, since it forms syncytium and secretes hormones after treatment with cAMP or forskolin. In contrast, the JEG-3 cell line fails to undergo substantial fusion. Therefore, BeWo and JEG-3 cells were used to identify a set of genes responsible for trophoblast fusion. Cells were treated with forskolin for 48 h to induce fusion. RNA was extracted, hybridised to Affymetrix HuGene ST1.0 arrays and analysed using system biology. Trophoblast differentiation was evaluated by real-time PCR and immunocytochemistry analysis. Moreover, some of the identified genes were validated by real-time PCR and their functional capacity was demonstrated by western blot using phospho-specific antibodies and CRISPR/cas9 knockdown experiments. Our results identified a list of 32 altered genes in fused BeWo cells compared to JEG-3 cells after forskolin treatment. Among these genes, four were validated by RT-PCR, including salt-inducible kinase 1 (SIK1) gene which is specifically upregulated in BeWo cells upon fusion and activated after 2 min with forskolin. Moreover, silencing of SIK1 completely abolished the fusion. Finally, SIK1 was shown to be at the center of many biological and functional processes, suggesting that it might play a role in trophoblast differentiation. In conclusion, this study identified new target genes implicated in trophoblast fusion. More studies are required to investigate the role of these genes in some placental pathology.

MicroRNA‑142‑3p inhibits trophoblast cell migration and invasion by disrupting the TGF‑β1/Smad3 signaling pathway

Insufficient invasion of trophoblasts is known to be associated with preeclampsia (PE) development. Recently, microRNAs (miRNAs) have been reported to serve important roles in the pathogenesis of PE. However, little is known regarding the regulation of trophoblastic invasion by miRNAs. The aim of the present study was to explore the role of miRNAs in trophoblastic invasion and the underlying molecular mechanism. Using a miRNA microarray, miRNAs putatively involved in the pathophysiology of PE were examined between normal and preeclamptic placentas. Validation analysis of miR‑142‑3p level in placenta specimens was performed using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). Then, the regulation of miR‑142‑3p on trophoblast cells migration and invasion was evaluated using wound healing and transwell migration assays. Furthermore, the target gene of miR‑142‑3p and the downstream signaling pathway were also investigated. Microarray analysis and RT‑qPCR revealed that miR‑142‑3p was significantly upregulated in placenta specimens from patients with PE. Its overexpression inhibited trophoblast cell invasion and migration, whereas its knockdown enhanced trophoblast cell invasion and migration. In addition, overexpression of miR‑142‑3p inhibited the mRNA expression and the activities of matrix metalloproteinase‑2 (MMP2) and MMP9, which are closely associated with cell invasion and migration, while inhibition of miR‑142‑3p had the opposite result. Subsequent analyses demonstrated that transforming growth factor‑β1 (TGF‑β1) was a direct and functional target of miR‑142‑3p. Notably, the knockdown of TGF‑β1 effectively reversed the enhancement of miR‑142‑3p inhibitor on trophoblast cell invasion and migration. Finally, the present study confirmed that miR‑142‑3p inhibitor enhanced cell invasion and migration by reactivating the TGF‑β1/Smad3 signaling pathway. Taken together, the results of the present study suggest that miR‑142‑3p may serve an important role in human placental development by suppressing trophoblast cell invasion and migration through disruption of the TGF‑β1/smad3 signaling pathway, suggesting that knockdown of miR‑142‑3p may provide a novel therapy for PE.

Role of insulin, adenosine, and adipokine receptors in the foetoplacental vascular dysfunction in gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a disease of pregnancy associated with maternal and foetal hyperglycaemia and altered foetoplacental vascular function. Human foetoplacental microvascular and macrovascular endothelium from GDM pregnancy show increased maximal l-arginine transport capacity via the human cationic amino acid transporter 1 (hCAT-1) isoform and nitric oxide (NO) synthesis by the endothelial NO synthase (eNOS). These alterations are paralleled by lower maximal transport activity of the endogenous nucleoside adenosine via the human equilibrative nucleoside transporter 1 (hENT1) and activation of adenosine receptors. A causal relationship has been described for adenosine-activation of A_2A adenosine receptors, hCAT-1, and eNOS activity (i.e. the Adenosine/l-Arginine/Nitric Oxide, ALANO, signalling pathway). Insulin restores these alterations in GDM via activation of insulin receptor A (IR-A) form in the macrovascular but IR-A and IR-B forms in the microcirculation of the human placenta. Adipokines are secreted from adipocytes influencing the foetoplacental metabolic and vascular function. Various adipokines are dysregulated in GDM, with adiponectin and leptin playing major roles. Abnormal plasma concentration of these adipokines and the activation or their receptors are involved in the pathophysiology of GDM. However, involvement of adipokines, adenosine, and insulin receptors and membrane transporters in the aetiology of this disease of pregnancy is unknown. This review focuses on the pathophysiology of insulin and adenosine receptors and l-arginine and adenosine membranes transporters giving an overview of the key adipokines leptin and adiponectin in the foetoplacental vasculature in GDM. This article is part of a Special Issue entitled: Membrane Transporters and Receptors in Pregnancy Metabolic Complications edited by Luis Sobrevia.

Transforming Growth Factor Beta has Dual Effects on MMP9 and uPA Expression in HTR-8/SVneo Human Trophoblastic Cell Line

Invasion of trophoblast into endometrium is vital for successful pregnancy development. MMP9 and uPA are key proteases in this process, but it is still not clear the regulation of its expression by Transforming Growth Factor Beta (TGF-β), known negative regulator of trophoblast invasion. We evaluated the effect of TGF-β on the transcriptional expression of uPA and MMP9 over time, in HTR- /SVneo trophoblast cells cultured with or without 0.5 % fetal bovine serum, via RT qPCR. The involved transcription factors and signaling pathways were analyzed in silico, using Proscan, Enrich, PCViz and WikiPathway. Results showed that that TGF-β regulates the expression of uPA and MMP9. Serum modified the nature of TGF-β’s effects on uPA expression, from negative without serum to positive with it, showing opposite effects on MMP9 expression. In silico analysis evidenced different transcription factors for each protease, some belonging to TGF-β ssignaling pathway, and crosstalk with MAPK and Wnt/β-catenin pathways. The TGF-β ddual role is discussed proposing that serum affects the cellular context. Transcriptional regulation of MMP9 and uPA by TGF-β is differential and depends on serum presence and evaluation time.

Pharmacotherapy for gestational diabetes

INTRODUCTION

Gestational diabetes mellitus (GDM) represents impaired carbohydrate metabolism during pregnancy and is characterized by progressive insulin resistance and compensatory hyperinsulinaemia. If inadequately treated, it may lead to fetal macrosomia and other adverse outcomes.

AREAS COVERED

In this review, the authors summarize the current evidence from studies on the use of insulin and other agents for the treatment of women with GDM.

EXPERT OPINION

Lifestyle management is of paramount importance for the treatment of GDM. In pharmacotherapy, insulin remains the long-established mainstay of treatment. NPH (Neutral Protamine Hagedorn) and soluble human insulin have long been established for use, but favorable experience has now also accumulated with the newer insulins (aspart, lispro, detemir). Alternatively, metformin and glyburide have been used in GDM, but they have never gained wide acceptance. Nutritional supplements based on micronutrients and bioactives (probiotics and myoinositol) have shown promising results as well. Further experience with incretin agents (DPP-4 inhibitors and GLP-1 receptor agonists) is awaited.

The effect of maternal NODAL on STOX1 expression in extravillous trophoblasts is mediated by IGF1

The number of molecules identified to be involved in communication between placenta and decidua is fast expanding. Previously, we showed that NODAL expressed in maternal endometrial stromal cells is able to affect NODAL and STOX1 expression in placental extravillous trophoblasts. The effect of maternal NODAL on placental NODAL expression is achieved via Activin A, while preliminary data suggests that maternal NODAL affects STOX1 expression in trophoblasts potentially via IGF1. In the current study, T-HESC endometrial stromal cells were treated with siRNAs against NODAL after which IGF1 mRNA expression was determined by quantitative RT-PCR, while IGF1 secretion was measured by ELISA. Recombinant IGF1 and inhibitors of the MAPK and PI3K/AKT pathways were added to SGHPL-5 extravillous trophoblasts after which the effects on STOX1 mRNA and STOX1 protein expression were determined. The effect of IGF1 and the MAPK and PI3K/AKT inhibitors on the invasive capacity of SGHPL-5 cells was investigated by performing invasion assays. We found that T-HESC cells treated with NODAL siRNAs showed significant upregulation of IGF1 mRNA expression and IGF1 protein secretion. Addition of IGF1 to SGHPL-5 cell media significantly upregulated STOX1 mRNA and protein expression. Using inhibitors of the PI3K/AKT and MAPK pathway showed that the effect of IGF1 on STOX1 expression is accomplished via MAPK signaling. Secondly, PI3K inhibition independently leads to reduced STOX1 expression which can be rescued by adding IGF1. IGF1 was unable to influence the invasive capacity of SGHPL-5 cells, while inhibiting the PI3K/AKT pathway did reduce the invasion of these cells. To conclude, here we show that downregulated NODAL expression in endometrial stromal cells, previously associated with pre-eclampsia like symptoms in mice, increases IGF1 secretion. Increased levels of IGF1 lead to increased expression levels of STOX1 in extravillous trophoblasts via the MAPK pathway, hereby identifying a novel signaling cascade involved in maternal-fetal communication.

Synergistic effects of tumor necrosis factor-α and insulin-like growth factor-I on survival of human trophoblast-derived BeWo cell line

OBJECTIVE

Trophoblast survival is regulated by cytokines and growth factors. While the pharmacological levels (10-100 ng/mL) of tumor necrosis factor (TNF)- α affect trophoblasts survival in vitro, the effects of the physiological levels (1-10 pg/mL) of TNF-α remain unknown. We investigated the effects of the physiological levels of TNF-α on proliferation and apoptosis of human trophoblast cells by using BeWo cells. Insulin-like growth factor (IGF)-I is also a potent regulator of trophoblast survival and has been known to exert synergistic effects with other hormones. The interaction of IGF-I and TNF-α on BeWo cells survival was also examined.

METHODS

After incubating BeWo under the presence of TNF-α (10-10⁵ pg/mL) and IGF-I (10² ng/mL), we assessed cell number by WST-1 assay and cell proliferation by BrdU uptake assay and immunocytochemistry with anti-Ki67 antibody. Apoptosis was evaluated by TUNEL assay and caspase-3, 8 activity assays.

RESULTS

Under the presence of IGF-I, cell number, BrdU uptake, and Ki-67 expression of BeWo were dose-dependently enhanced by low TNF-α (10-10² pg/mL), while no such effects were detected without IGF-I. Higher levels of TNF-α (10⁴-10⁵ pg/mL) showed inhibiting effects on cell number and cell proliferation. The number of TUNEL positive cells were decreased and caspase activities were suppressed by lower levels (10-10² pg/mL) of TNF-α and IGF-I independently. Higher levels of TNF-α (10⁴-10⁵ pg/mL) showed promoting effects on apoptosis irrespective of IGF-I.

CONCLUSION

The physiological levels of TNF-α and IGF-I had synergetic effects on enhancing cell proliferation and also independently inhibited apoptosis of Bewo cells.

The care of pregestational and gestational diabetes and drug metabolism considerations

INTRODUCTION

Normal pregnancy development involves gradual decline in insulin sensitivity, which sometimes requires pharmacotherapy. Insulin is the drug of choice for gestational and pregestational diabetes. Metabolism of traditional insulins results in inadequate onset and duration of action and marked peak activity. These properties increase risk of excessive glucose excursions, which are especially undesirable during pregnancy. Insulin analogs have been emerging as a safer and more effective treatment of diabetes during pregnancy. Areas covered: This manuscript reviews currently used antihyperglycemic agents: fast and long-acting insulins, metformin and glyburide. Trials demonstrating their efficacy and safety during pregnancy are described. Certain drug metabolism considerations (e.g. affinity to IGF-1) are emphasized. Expert opinion: The theories that insulin analogs bind to immunoglobulin and cross placenta have been disproved. Lispro, aspart, glargine and detemir do not transfer across the placenta and do not result in adverse maternal and neonatal outcomes. In addition, favorable pharmacokinetic profiles (rapid onset and 24-hour near peakless activity) substantially reduce blood glucose variability including hypoglycemia. We believe that insulin analogs should be given strong consideration for the treatment of diabetes during pregnancy. Metformin has also proven to be safe and may be considered as an initial single agent for milder gestational diabetes.

Serum depletion induces changes in protein expression in the trophoblast-derived cell line HTR-8/SVneo

BACKGROUND

How nutrition and growth factor restriction due to serum depletion affect trophoblast function remains poorly understood. We performed a proteomic differential study of the effects of serum depletion on a first trimester human immortalized trophoblast cell line.

METHODS

The viability of HTR-8/SVneo trophoblast cells in culture with 0, 0.5 and 10 % fetal bovine serum (FBS) were assayed via MTT at 24, 48 and 64 h. A comparative proteomic analysis of the cells grown with those FBS levels for 24 h was performed using two-dimensional electrophoresis (2DE), followed by mass spectrometry for protein spot identification, and a database search and bioinformatics analysis of the expressed proteins. Differential spots were identified using the Kolmogorov-Smirnov test (n = 3, significance level 0.10, D > 0.642) and/or ANOVA (n = 3, p < 0.05).

RESULTS

The results showed that low serum doses or serum depletion differentially affect cell growth and protein expression. Differential expression was seen in 25 % of the protein spots grown with 0.5 % FBS and in 84 % of those grown with 0 % FBS, using 10 % serum as the physiological control. In 0.5 % FBS, this difference was related with biological processes typically affected by the serum, such as cell cycle, regulation of apoptosis and proliferation. In addition to these changes, in the serum-depleted proteome we observed downregulation of keratin 8, and upregulation of vimentin, the glycolytic enzymes enolase and pyruvate kinase (PKM2) and tumor progression-related inosine-5'-monophosphate dehydrogenase 2 (IMPDH2) enzyme. The proteins regulated by total serum depletion, but not affected by growth in 0.5 % serum, are members of the glycolytic and nucleotide metabolic pathways and the epithelial-to-mesenchymal transition (EMT), suggesting an adaptive switch characteristic of malignant cells.

CONCLUSIONS

This comparative proteomic analysis and the identified proteins are the first evidence of a protein expression response to serum depletion in a trophoblast cell model. Our results show that serum depletion induces specific changes in protein expression concordant with main cell metabolic adaptations and EMT, resembling the progression to a malignant phenotype.

Insulin Exhibits an Antiproliferative and Hypertrophic Effect in First Trimester Human Extravillous Trophoblasts

Our aim was to investigate the effect of high levels of glucose, insulin, leptin, and tumor necrosis factor alpha, biomarkers of diabetes in pregnancy, in the process of placentation, using as a cell model a first trimester extravillous human trophoblast cell line (HTR8/SVneo cells). Exposure of HTR8/SVneo cells for 24 hours to either glucose (20 mmol/L) or leptin (25-100 ng/mL) did not cause significant changes in cell proliferation and viability. Tumor necrosis factor alpha (24 hours; 10-100 ng/L) caused a small decrease (10%) in cell proliferation and an increase (9%) in cell viability; however, both effects disappeared when exposure time was increased. Insulin (24 hours; 1-10 nmol/L) caused a concentration- and time-dependent decrease (10%-20%) in cell proliferation; the effect of insulin (10 nmol/L) was more pronounced after a 48 hours exposure (35%). In contrast, exposure to insulin (10 nmol/L; 48 hours) showed no significant effect on cell viability, apoptosis, and migration capacity. Insulin appears to cause hypertrophy of HTR8/SVneo cells as it reduces the cell mitotic index while increasing the culture protein content. The antiproliferative effect of insulin seems to involve activation of mammalian target of rapamycin, phosphoinositide 3-kinase, and p38 mitogen-activated protein kinase. Finally, simvastatin and the polyphenol quercetin potentiated the antiproliferative effect of insulin; on the contrary, the polyphenol resveratrol, the polyunsaturated fatty acids eicosapentaenoic and docosahexaenoic acids, and folic acid were not able to change it. In conclusion, we show that insulin has an antiproliferative and hypertrophic effect on a first trimester extravillous human trophoblast cell line. So insulin might affect the process of placentation.

STAT3 and ERK Signaling Pathways Are Implicated in the Invasion Activity by Oncostatin M through Induction of Matrix Metalloproteinases 2 and 9

PURPOSE

Our previous studies have shown that oncostatin M (OSM) promotes trophoblast invasion activity through increased enzyme activity of matrix metalloproteinase (MMP)-2 and -9. We further investigated OSM-induced intracellular signaling mechanisms associated with these events in the immortalized human trophoblast cell line HTR8/SVneo.

MATERIALS AND METHODS

We investigated the effects of OSM on RNA and protein expression of MMP-2 and -9 in the first-trimester extravillous trophoblast cell line (HTR8/SVneo) via Western blot. The selective signal transducer and activator of transcription (STAT)3 inhibitor, stattic, STAT3 siRNA, and extracellular signal-regulated kinase (ERK) siRNA were used to investigate STAT3 and ERK activation by OSM. The effects of STAT3 and ERK inhibitors on OSM-induced enzymatic activities of MMP-2 and -9 and invasion activity were further determined via Western blot and gelatin zymography.

RESULTS

OSM-induced MMP-2 and -9 protein expression was significantly suppressed by STAT3 inhibition with stattic and STAT3 siRNA silencing, whereas the ERK1/2 inhibitor (U0126) and ERK silencing significantly suppressed OSM-induced MMP-2 protein expression. OSM-induced MMP-2 and MMP-9 enzymatic activities were significantly decreased by stattic pretreatment. The increased invasion activity induced by OSM was significantly suppressed by STAT3 and ERK1/2 inhibition, though to a greater extent by STAT3 inhibition.

CONCLUSION

Both STAT3 and ERK signaling pathways are involved in OSM-induced invasion activity of HTR8/SVneo cells. Activation of STAT3 appears to be critical for the OSM-mediated increase in invasiveness of HTR8/SVneo cells.

Corticosterone alters materno-fetal glucose partitioning and insulin signalling in pregnant mice

Glucocorticoids affect glucose metabolism in adults and fetuses, although their effects on materno-fetal glucose partitioning remain unknown. The present study measured maternal hepatic glucose handling and placental glucose transport together with insulin signalling in these tissues in mice drinking corticosterone either from day (D) 11 to D16 or D14 to D19 of pregnancy (term = D21). On the final day of administration, corticosterone-treated mice were hyperinsulinaemic (P < 0.05) but normoglycaemic compared to untreated controls. In maternal liver, there was no change in glycogen content or glucose 6-phosphatase activity but increased Slc2a2 glucose transporter expression in corticosterone-treated mice, on D16 only (P < 0.05). On D19, but not D16, transplacental (3) H-methyl-d-glucose clearance was reduced by 33% in corticosterone-treated dams (P < 0.05). However, when corticosterone-treated animals were pair-fed to control intake, aiming to prevent the corticosterone-induced increase in food consumption, (3) H-methyl-d-glucose clearance was similar to the controls. Depending upon gestational age, corticosterone treatment increased phosphorylation of the insulin-signalling proteins, protein kinase B (Akt) and glycogen synthase-kinase 3β, in maternal liver (P < 0.05) but not placenta (P > 0.05). Insulin receptor and insulin-like growth factor type I receptor abundance did not differ with treatment in either tissue. Corticosterone upregulated the stress-inducible mechanistic target of rapamycin (mTOR) suppressor, Redd1, in liver (D16 and D19) and placenta (D19), in ad libitum fed animals (P < 0.05). Concomitantly, hepatic protein content and placental weight were reduced on D19 (P < 0.05), in association with altered abundance and/or phosphorylation of signalling proteins downstream of mTOR. Taken together, the data indicate that maternal glucocorticoid excess reduces fetal growth partially by altering placental glucose transport and mTOR signalling.

Treating diabetes during pregnancy

INTRODUCTION

Gestational diabetes mellitus (GDM), defined as glucose intolerance with first recognition or onset during pregnancy, is steadily rising in prevalence. GDM affects ∼ 3 - 5% of pregnancies in the US and is associated with significant adverse perinatal and maternal outcomes. Diagnosing and treating GDM early in pregnancy is of utmost importance as it can prevent poor outcomes such as macrosomia, shoulder dystocia and obstetric complications.

AREAS COVERED

This review describes the importance of treating GDM and the various available interventions for glycemic control in women with GDM, including the latest evidence regarding pharmacological treatments and specifically anti-hyperglycemic agents. It deals with timing of pharmacological treatments, recommended doses and what pharmacological agent should be used.

EXPERT OPINION

Unless diagnosed late during pregnancy, a stepwise approach is the best way to treat GDM, beginning with diet and exercise and proceeding to pharmacological interventions if failure occurred. Although insulin is the dominant treatment, the use of anti-hyperglycemic agents such as glyburide and metformin in treating GDM has gained popularity and consideration should be made using these agents as first-line pharmacological treatment. Anti-hyperglycemic agents do not require frequent monitoring or injections and may therefore appeal more to patients. Further studies are needed regarding long-acting insulin and other anti-hyperglycemic agents such as thiazolidinediones, as well as identifying treatment options more specific to an individual based on risk factors and other variables predicting treatment outcomes in GDM.

Obstetric conditions and the placental weight ratio

INTRODUCTION

To elucidate how obstetric conditions are associated with atypical placental weight ratios (PWR)s in infants born: (a) ≥37 weeks gestation; (b) at ≥33 but <37 weeks gestation; and (c) <33 weeks gestation.

METHODS

The study included all in-hospital singleton births in London, Ontario between June 1, 2006 and March 31, 2011. PWR was assessed as <10th or >90th percentile by gestational age-specific local population standards. Multivariable analysis was carried out using multinomial logistic regression with blockwise variable entry in order of temporality.

RESULTS

Baseline factors and maternal obstetric conditions associated with PWR <10th percentile were: increasing maternal height, overweight and obese body mass indexes (BMI), large for gestational age infants, smoking, and gestational diabetes. Obstetric factors associated with PWR >90th percentile were: underweight, overweight and obese BMIs, smoking, preeclampsia, placenta previa, and placental abruption. In particular, indicators of hypoxia and altered placental function were generally associated with elevated PWR at all gestations.

DISCUSSION

An association between obstetric conditions associated with fetal hypoxia and PWR ≥90th percentile was illustrated.

CONCLUSIONS

The multivariable findings suggest that the PWR is similarly increased regardless of the etiology of the hypoxia.

Regulation of amino acid transporters by adenoviral-mediated human insulin-like growth factor-1 in a mouse model of placental insufficiency in vivo and the human trophoblast line BeWo in vitro

Previous work in our laboratory demonstrated that over-expression of human insulin-like growth factor-11 (hIGF-1) in the placenta corrects fetal weight deficits in mouse, rat, and rabbit models of intrauterine growth restriction without changes in placental weight. The underlying mechanisms of this effect have not been elucidated. To investigate the effect of intra-placental IGF-1 over-expression on placental function we examined amino acid transporter expression and localization in both a mouse model of placental Insufficiency (PI) and a model of human trophoblast, the BeWo Choriocarcinoma cell line. For in vitro human studies, BeWo Choriocarcinoma cells were maintained in F12 complete medium + 10%FBS. Cells were incubated in serum-free control media ± Ad-IGF-1 or Ad-LacZ for 48 h. MOIs of 10:1 and 100:1 were utilized. In BeWo, transfection efficiency was 100% at an MOI of 100:1 and Ad-IGF-1 significantly increased IGF-1 secretion, proliferation and invasion but reduced apoptosis compared to controls. In vitro, amino acid uptake was increased following Ad-IGF-1 treatment and associated with significantly increased RNA expression of SNAT1, 2, LAT1 and 4F2hc. Only SNAT2 protein expression was increased but LAT1 showed relocalization from a perinuclear location to the cytoplasm and cell membrane. For in vivo studies, timed-pregnant animals were divided into four groups on day 18; sham-operated controls, uterine artery branch ligation (UABL), UABL + Ad-hIGF-1 (10(8) PFU), UABL + Ad-LacZ (10(8) PFU). At gestational day 20, pups and placentas were harvested by C-section. Only LAT1 mRNA expression changed, showing that a reduced expression of the transporter levels in the PI model could be partially rectified with Ad-hIGF1 treatment. At the protein level, System L was reduced in PI but remained at control levels following Ad-hIGF1. The System A isoforms were differentially regulated with SNAT2 expression diminished but SNAT1 increased in PI and Ad-hIGF1 groups. Enhanced amino acid isoform transporter expression and relocalization to the membrane may be an important mechanism contributing to Ad-hIGF-1 mediated correction of placental insufficiency.

Interleukin-1β inhibits insulin signaling and prevents insulin-stimulated system A amino acid transport in primary human trophoblasts

Interleukin-1β (IL-1β) promotes insulin resistance in tissues such as liver and skeletal muscle; however the influence of IL-1β on placental insulin signaling is unknown. We recently reported increased IL-1β protein expression in placentas of obese mothers, which could contribute to insulin resistance. In this study, we tested the hypothesis that IL-1β inhibits insulin signaling and prevents insulin-stimulated amino acid transport in cultured primary human trophoblast (PHT) cells. Cultured trophoblasts isolated from term placentas were treated with physiological concentrations of IL-1β (10pg/ml) for 24h. IL-1β increased the phosphorylation of insulin receptor substrate-1 (IRS-1) at Ser307 (inhibitory) and decreased total IRS-1 protein abundance but did not affect insulin receptor β expression. Furthermore, IL-1β inhibited insulin-stimulated phosphorylation of IRS-1 (Tyr612, activation site) and Akt (Thr308) and prevented insulin-stimulated increase in PI3K/p85 and Grb2 protein expression. IL-1β alone stimulated cRaf (Ser338), MEK (Ser221) and Erk1/2 (Thr202/Tyr204) phosphorylation. The inflammatory pathways nuclear factor kappa B and c-Jun N-terminal kinase, which are involved in insulin resistance, were also activated by IL-1β treatment. Moreover, IL-1β inhibited insulin-stimulated System A, but not System L amino acid uptake, indicating functional impairment of insulin signaling. In conclusion, IL-1β inhibited the insulin signaling pathway by inhibiting IRS-1 signaling and prevented insulin-stimulated System A transport, thereby promoting insulin resistance in cultured PHT cells. These findings indicate that conditions which lead to increased systemic maternal or placental IL-1β levels may attenuate the effects of maternal insulin on placental function and consequently fetal growth.

Consequences of gestational and pregestational diabetes on placental function and birth weight

Maternal diabetes constitutes an unfavorable environment for embryonic and fetoplacental development. Despite current treatments, pregnant women with pregestational diabetes are at increased risk for congenital malformations, materno-fetal complications, placental abnormalities and intrauterine malprogramming. The complications during pregnancy concern the mother (gravidic hypertension and/or preeclampsia, cesarean section) and the fetus (macrosomia or intrauterine growth restriction, shoulder dystocia, hypoglycemia and respiratory distress). The fetoplacental impairment and intrauterine programming of diseases in the offspring’s later life induced by gestational diabetes are similar to those induced by type 1 and type 2 diabetes mellitus. Despite the existence of several developmental and morphological differences in the placenta from rodents and women, there are similarities in the alterations induced by maternal diabetes in the placenta from diabetic patients and diabetic experimental models. From both human and rodent diabetic experimental models, it has been suggested that the placenta is a compromised target that largely suffers the impact of maternal diabetes. Depending on the maternal metabolic and proinflammatory derangements, macrosomia is explained by an excessive availability of nutrients and an increase in fetal insulin release, a phenotype related to the programming of glucose intolerance. The degree of fetal damage and placental dysfunction and the availability and utilisation of fetal substrates can lead to the induction of macrosomia or intrauterine growth restriction. In maternal diabetes, both the maternal environment and the genetic background are important in the complex and multifactorial processes that induce damage to the embryo, the placenta, the fetus and the offspring. Nevertheless, further research is needed to better understand the mechanisms that govern the early embryo development, the induction of congenital anomalies and fetal overgrowth in maternal diabetes.

Effect of pituitary growth hormone and insulin-like growth factor type-I on proliferation, apoptosis and hormone secretion of the placental cell line JEG-3

OBJECTIVE

Placenta human choriocarcinoma JEG-3 cells were used to study the possibility that pituitary growth hormone (GH) and insulin-like growth factor type I (IGF-I) act on first trimester of pregnancy progesterone (P4) and human chorionic gonadotropin (hCG) secretion, cell proliferation and apoptosis.

MATERIAL AND METHODS

The JEG-3 cell line was cultured in Dulbecco modified eagle medium without phenol red containing 10% FBS. The cells were plated in 96-well plates at the density of 3 x 10(3) for 24 h and treated with 10, 50, 100, or 200 ng/ml of GH or 10, 30, 100, or 250 ng/ml of IGF-I for 24 h. At the end of the culture period, cell proliferation was measured using the BrdU colorimetric assay and caspase-3 activity, as a marker of apoptosis, was determined by the colorimetric method. Media were frozen for hormone analysis by enzyme immunoassay. Results. We found that the stimulatory activities of GH and IGF-I on both P4 and hCG secretion paralleled the stimulation of cell proliferation and inhibition of apoptosis.

CONCLUSION

Our findings suggest an important role for pituitary GH and IGF-I in normal placental function during the first trimester of pregnancy.

Comparative proteomic analysis of the insulin-induced L6 myotube secretome

Emerging evidence has revealed an endocrine function for skeletal muscle; in fact, certain anti-inflammatory cytokines are secreted only from contractile skeletal muscle. However, the skeletal muscle secretome as a whole is poorly characterized, as is how it changes in response to extracellular stimuli. Herein, we sought to identify and characterize the members of the skeletal muscle secretome, and to determine which protein secretion levels were modulated in response to insulin stimulation. To conduct these studies, we treated differentiated L6 rat skeletal muscle cells with insulin or left them untreated, and we comparatively analyzed the proteins secreted into the media. We fractionated this conditioned media using offline RP HPLC, digested the fractionated proteins, and analyzed the resulting peptides with LC-ESI-MS/MS. We identified a total of 254 proteins, and by using three different filtering methods, we identified 153 of these as secretory proteins. Fourteen proteins were secreted at higher levels under insulin stimulation, including several proteins known to be highly secreted in metabolic diseases; 19 proteins were secreted at lower levels under insulin stimulation. These result not only pinpointed several previously unknown, insulin induced, secretory proteins of skeletal muscle, it also described a novel approach for conditioned secretome analysis.

The granulocyte colony stimulating factor (G-CSF) activates Jak/STAT and MAPK pathways in a trophoblastic cell line

Granulocyte colony-stimulating factor receptor (G-CSFR) has been found in placenta tissues, although its functional role has not yet been defined. In order to explore the molecular pathways induced by G-CSF in this tissue, we first reveal the presence of G-CSFR in the JEG-3 human trophoblastic cell line and then examined the phosphorylation of Janus tyrosine kinases (Jak), signal transducers and activators of transcription (STAT) proteins and mitogen-activated protein kinases (MAPK) after G-CSF binding to receptors. We showed that Jak1, Jak2, Tyk2, and STAT3 were phosphorylated after incubation with G-CSF. Phosphorylation of p38 and p44/42 MAPK was also activated by G-CSF, and specifically blocked in the presence of the corresponding inhibitors. Similar intracellular pathways were induced by G-CSF in a myeloid leukemia NFS-60 cell line that was studied in parallel. Conversely to cytokine action in myeloid cells, G-CSF did not induce a proliferative response in JEG-3 cells. When the effect of G-CSF on cellular viability was evaluated, cytokine-stimulated JEG-3 cells were protected from foetal serum starvation. In addition, when JEG-3 cells deprived of serum were incubated at different times in the presence of G-CSF, a progressive decrease in the percentage of hypodiploid cells was observed. In summary, we identified the molecular pathways activated after G-CSF binding to trophoblastic cell receptors and showed that G-CSF behaved as a protective cytokine, which supports JEG-3 cells survival.

AQP1 gene expression is upregulated by arginine vasopressin and cyclic AMP agonists in trophoblast cells

Aquaporins (AQPs) are water channels that regulate water flow in many tissues. As AQP1 is a candidate to regulate placental fluid exchange, we sought to investigate the effect of arginine vasopressin (AVP) and cAMP agonists on AQP1 gene expression in first trimester-derived extravillous cytotrophoblasts (HTR-8/Svneo) and two highly proliferative carcinoma trophoblast-like cell lines but with a number of functional features of the syncytiotrophoblast namely; JAR and JEG-3 cells. Our data demonstrated that AVP (0.1 nM) significantly increased the expression of AQP1 mRNA at 10 h in HTR-8/SVneo and JEG-3 cells (P<0.05). Both SP-cAMP, a membrane-permeable and phosphodiesterase resistant cAMP, and forskolin, an adenylate cyclase stimulator significantly increased AQP1 mRNA expression in all cell lines after 2 h in a dose-dependent manner (P<0.05) with a parallel increase in protein expression. In the time course study, 5 microM of either SP-cAMP or forskolin significantly stimulated AQP1 mRNA expression after 2 h in HTR-8/SVneo cells and after 10 h in JAR and JEG-3 cells. AQP1 protein expression was highest after 20 h in both HTR-8/SVneo and JEG-3 cells (P<0.05). AVP-stimulated cAMP elevation was blocked in the presence of 9-(tetrahydro-2'-furyl) adenine (SQ22536) (100 microM), a cell-permeable adenylate cyclase inhibitor (P<0.05). These results indicate that in trophoblasts-like cells AQP1 gene expression is upregulated by both AVP and cAMP agonists. Furthermore, our data demonstrate that a cAMP-dependent pathway is responsible for the AVP effect on AQP1. Thus, modulation of AQP1 expression by maternal hormones may regulate invasion and fetal-placental-amnion water homeostasis during gestation.

Comparison of cell cycle regulatory gene mRNA in three different types of human trophoblasts and effect of transforming growth factor

AIM

Identifying the factors responsible for reducing the proliferation, syncytialization, and invasiveness of trophoblast tissues, as seen with preeclampsia, intrauterine growth restriction, and spontaneous miscarriage, is a current challenge in reproductive biology. These factors, transforming growth factor (TGF)-beta as an example, can work by altering trophoblast differentiation or proliferation. We therefore investigated and compared specific markers of trophoblast proliferation and differentiation in three commonly used trophoblast tissue cell models, and also investigated the influence of TGF-beta on these markers.

METHODS

In this study, we isolated human trophoblasts from first trimester and term placentas, and additionally used human choriocarcinoma cells (JEG-3). Baseline values of human chorionic gonadotropin (hCG) secretion and relative mRNA levels of cell cycle regulators (cyclin E, p21, p27, and p57) were investigated for each cell type. We also investigated the influence of TGF-beta on these parameters.

RESULTS

Quantitative and longitudinal production of hCG differed between the three cell types. Significantly different amounts of cyclin E, p21, p27, and p57 mRNA were demonstrated within each cell type, as well as between all the cell types, throughout the culture time period. Each trophoblast type demonstrated a reduction of hCG secretion in response to TGF-beta. TGF-beta did not show a consistent effect on the cell cycle mRNA of any of the cell types.

CONCLUSION

We were able to characterize and compare the differential production of hCG, as well as the differential expression of cell cycle-associated mRNA of early trophoblasts, term trophoblasts, and choriocarcinoma cells. The production of hCG was altered by TGF-beta, although mRNA levels were not markedly altered by TGF-beta.

Myostatin regulates glucose uptake in BeWo cells

Myostatin is a member of the transforming growth factor (TGF)-beta superfamily, known for its ability to inhibit muscle growth. It can also regulate metabolism and glucose uptake in a number of tissues. To determine the mechanism of myostatin's effect on glucose uptake, we evaluated its actions using choriocarcinoma cell lines that are widely used as models for placental cells. Protein and mRNA were determined using immunoblotting and RT-PCR/PCR, respectively. Glucose uptake was assessed by uptake of radiolabeled deoxyglucose in vitro. All choriocarcinoma cell lines tested i.e., BeWo, JEG, and Jar, are used as models of placental cells, and all expressed myostatin protein and mRNA. Treatment of BeWo cells with myostatin resulted in inhibition of glucose uptake in a concentration-dependent manner (P < 0.01). At all concentrations tested, follistatin, a functional inhibitor of myostatin, completely blocked the inhibitory effect of myostatin (40 nM) on glucose uptake by BeWo cells (0.4 nM, P < 0.05). Follistatin treatment alone also increased glucose uptake (0.4 and 4 nM, P < 0.001; 40 nM, P < 0.05). Because BeWo cells proliferated and greater cell densities were achieved, glucose uptake declined irrespective of treatment. Myostatin treatment of BeWo cells did not alter the levels of myostatin receptor, ActRII A/B proteins. The levels of glucose transport proteins also remained unaltered in BeWo cells with myostatin treatment. This study has shown that myostatin specifically inhibits glucose uptake into BeWo cells, suggesting that locally produced myostatin may control glucose metabolism within the placenta.

Insulin analogues in the treatment of diabetes in pregnancy

This review reports the literature on the safety and efficacy of insulin analogues in pregnancy and thereby enables the clinician to choose the optimal insulin treatment protocol to achieve and maintain normoglycemia throughout pregnancies complicated by diabetes. This article also reviews the literature on the insulin analog during pregnancy and presents the authors' opinion as to the safety and efficacy of insulin analog treatment for the pregnant diabetic woman.

Impaired migration of trophoblast cells caused by simvastatin is associated with decreased membrane IGF-I receptor, MMP2 activity and HSP27 expression

BACKGROUND

Statins inhibit 3-hydroxy-3-methylglutaryl coenzyme-A reductase, the rate-limiting enzyme of the mevalonate pathway, and are used successfully in the treatment of hypercholesterolaemia. Statins are contraindicated during pregnancy. Lately, we have shown that simvastatin has adverse affects on human first trimester placental explants' proliferation and migration. The objective of the present study was to investigate the molecules involved in mediating simvastatin's effect on trophoblast cell migration. We hypothesized that simvastatin attenuates insuline-like growth factor-I (IGF-I) receptor expression (involved in trophoblast motility), matrix metalloproteinase (MMP) activities, and heat shock protein 27 (HSP27) levels (whose mRNA is actively transcribed during trophoblast differentiation) in trophoblast cells thus consequently effecting their migration.

METHODS

Human placental explants were cultured above a matrigel with/without simvastatin (10 microM) for 5 days. In this model, trophoblast migrates from the villi into the matrigel. Western-blot and immunohistochemistry served for analysing HSP27 expression. Immunohistochemistry was used for assessing IGF-I receptor localization. MMPs activity was assayed by gel zymography.

RESULTS

Simvastatin reduced IGF-I receptor membranal expression, MMP2 activity and HSP27 expression in trophoblast cells (P < 0.05).

CONCLUSIONS

The inhibitory effect of simvastatin on trophoblast cell migration is associated with a significant decrease in the tested molecules, which probably contributes to the impaired migration.

Effect of low oxygen concentrations on trophoblast-like cell line invasion

The applicability of trophoblast-like cell lines to the study of trophoblast function has been widely debated. The present study investigated the effect of oxygen on the invasiveness, apoptosis, proliferation and secreted proteases of four different trophoblast cell lines; HTR-8/SVneo, SGHPL-4, JEG3 and JAR. All experiments were performed at 20% and 3% oxygen for 24, 48 and 72h. Immunostaining for integrins alpha1, alpha6 and beta3, cytokeratin 7 and HLA-G was used to determine the phenotype of the different cell lines. Invasion was assessed using the Matrigel invasion assay. Immunostaining for M30 and Ki67 determined levels of apoptosis and proliferation, respectively. Gelatin and casein/plasminogen zymography were performed on conditioned media to determine levels of secreted matrix metalloproteinase (MMP) 2 and MMP9 and urokinase plasminogen activator (uPA), respectively. None of the cell lines immunostained for all markers normally expressed by extravillous trophoblast cells. Invasiveness of HTR-8/SVneo and JEG3 cells cultured in 3% oxygen was increased after 24h but was inhibited by 72h in culture. Invasion of SGHPL-4 cells was inhibited after culture in 3% oxygen for 24h. Invasion by JAR cells was not affected by changes in oxygen concentration. The different cell lines also displayed different responses to culture period in 3% oxygen with respect to apoptosis, proliferation and secreted proteases. Care should be taken before results obtained using cell lines as a model for EVT are extrapolated to extravillous trophoblast cell behaviour in vivo.

Expression of melatoninergic receptors in human placental choriocarcinoma cell lines

BACKGROUND

Melatonin crosses the placenta and enters the fetal circulation. Moreover, experimental data suggest a possible influence of melatonin on placental function and fetal development in humans. To date, the expression and role of melatonin receptors in human placenta choriocarcinoma cell lines and in human term placental tissues remain to be elucidated.

METHODS AND RESULTS

Results from RT-PCR, western blotting and confocal microscopy demonstrated that the MT1, MT2 and RORalpha1 melatonin receptors are expressed in the human term placental tissues and in choriocarcinoma cell lines JEG-3 and BeWo. Furthermore, enzyme-linked immunosorbent assay showed that 6-chloromelatonin (a melatonin agonist) inhibits, in a dose-dependent manner, forskolin-stimulated hCG-beta secretion in JEG-3 (P < 0.001) and BeWo (P < 0.05) cells but had no effect on basal human chorionic gonadotrophin (hCG-beta) levels. This effect of 6-chloromelatonin on forskolin-stimulated HCG-beta secretion was abolished by pertussis toxin (PTX), suggesting that melatonin regulates hCG-beta production by an action involving an inhibitory Gi/o protein. In PTX-treated BeWo cells, 6-chloromelatonin stimulated basal hCG-beta secretion (P < 0.001).

CONCLUSION

These results demonstrate, for the first time, the expression of melatonin receptors in human term placental tissues and in choriocarcinoma cells and suggest a possible paracrine/autocrine function for melatonin in human placenta.

Differential effects of inducers of syncytialization and apoptosis on BeWo and JEG-3 choriocarcinoma cells

BACKGROUND

The interactions of trophoblasts with the cytokine network at the fetomaternal interface determine the pathway the cell undertakes, e.g. proliferation, differentiation and apoptosis.

METHODS

We used cultures of fusigenic BeWo and non-fusigenic JEG-3 choriocarcinoma cells to study the effects of inducers of syncytialisation (forskolin) and apoptosis [tumour necrosis factor-alpha (TNFalpha)] on differentiation, viability, proliferation and apoptosis.

RESULTS

E-cadherin immunostaining showed that syncytium formation was confined to BeWo and not JEG-3 cells, while secretion of hCG was promoted by forskolin in both cell types implying a 'dissociation' between morphological and biochemical differentiation. Forskolin also had differential effects on cell viability (MTT reduction test) and proliferation (Ki67 immunostaining with MIB-1 monoclonal antibody), both decreasing in BeWo and increasing in JEG-3 cells. TNFalpha increased apoptosis (cytokeratin neo-epitope immunostaining with M30 monoclonal antibody) in both cell types, an effect which was blocked by epidermal growth factor selectively in JEG-3 cells.

CONCLUSION

Our results suggest that the differential responses of BeWo and JEG-3 cells to inducers of syncytialization and apoptosis might be related to their fusigenic capacity. Caution is needed when extrapolating results obtained by these models to normal trophoblast populations. However, we speculate that these models can help identify key factors involved in trophoblast differentiation at the placental bed.

Simvastatin has deleterious effects on human first trimester placental explants

BACKGROUND

Statins inhibit 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMG-CoA reductase), the rate-limiting enzyme of the mevalonate pathway, and have been used successfully in the treatment of hypercholesterolaemia. Animal models have provided evidence for the teratogenic effects of statins on pregnancy outcome. Thus statins are contraindicated during pregnancy. However, conflicting data are available from inadvertent use of statins in human pregnancy. Therefore we decided to explore the effects of simvastatin on the placenta in an in vitro human placental model.

METHODS

Human first trimester placental explants that were grown on matrigel were exposed to medium supplemented with simvastatin. Migration of extravillous trophoblast cells was assessed by visual observation. Proliferative and apoptotic events of the trophoblast cells were assesed by immunohistochemical examination using anti-Ki67 and anti-activated caspase-3 antibodies respectively. Hormone levels were measured.

RESULTS

Simvastatin sharply inhibited migration of extravillous trophoblast cells from the villi to the matrigel (P < 0.05). Moreover, simvastatin inhibited half of the proliferative events in the villi (P < 0.05) and increased apoptosis of cytotrophoblast cells compared to control. Moreover, simvastatin significantly decreased secretion of progesterone from the placental explants (P < 0.01).

CONCLUSION

Simvastatin adversely affects human first trimester trophoblast.

Insulin-like growth factor-I alters apoptosis related genes and reduces apoptosis in porcine parthenotes developing in vitro

The aim of this study was to determine the effects of IGF-I on the viability and development of porcine presumptive diploid parthenotes developing in vitro. In vitro derived 2-cell parthenotes were cultured to blastocysts with or without exogenous IGF-I in the presence or absence of BSA. The addition of 10 or 100 ng/ml IGF-I into NCSU 23 medium did not enhance the development of 2-cell parthenotes to the blastocyst stage. However, IGF-I increased cell numbers (P < 0.001) in the presence of BSA. Similarly, IGF-I alone did not affect apoptosis in the blastocysts but when combined with BSA, it reduced apoptosis (P < 0.05). Real time reverse-transcription polymerase chain reaction revealed that IGF-I significantly decreased the mRNA expression (pro-apoptotic gene Fas or Bak and anti-apoptotic gene Bcl-xL) ratios of both Fas/Bcl-xL (P < 0.01) and Bak/Bcl-xL (P < 0.01) in the presence of 0.4% BSA. These data suggest that IGF-I synergies with BSA to act as a mitogen and apoptotic survival factor in porcine preimplantation parthenotes.

Influence of IGF-I on adhesion, proliferation, and galectin-1 production in JAr and Jeg-3 choriocarcinoma cell lines

BACKGROUND: JAr and Jeg-3 choriocarcinoma cell lines are model systems for the transformed trophoblast and allow studies of phenotype and regulatory factors for particular cell functions. Both cell lines express the receptor for insulin-like growth factor-I (IGF-I). Effects of IGF-I on adhesion, proliferation and galectin-1 production in JAr and Jeg-3 cells were studied. METHODS: The effects of IGF-I on proliferation and galectin-1 production were examined by thiazolyl blue assay and cell based solid phase assay using polyclonal anti-galectin-1 antibodies. The cell adhesion assay was performed on Matrigel coated wells. Galectin-1 production and localization was examined by immunocytochemistry. RESULTS: IGF-I decreased adhesion of JAr cells to 70% of the control value (p<0.05). Cell treatment with 10 ?g/L of IGF-I significantly increased viable cell number: by 13.5% in JAr and 6% in Jeg-3. Gal-1 was immunolocalized intracellularly and associated with the cell membrane in both cell lines. Production of galectin-1 was significantly increased after treatment with IGF-I compared to control: by 7% in JAr cells and by 16% in Jeg-3 cells (p<0.05). CONCLUSION: The data showed that IGF-I affected adhesion and proliferation of choriocarcinoma cells, depending on the cell line. Both choriocarcinoma cell lines studied here produced galectin-1. The amount of galectin-1 was moderately stimulated by IGF-I.

Endocrine cell lines from the placenta

Cell-lines derived from human placenta and chorion have been used extensively to model the endocrine functions of human trophoblast. In general terms, the endocrine functions of the primary cells and tissues are at least partially replicated within the cell-lines, suggesting that they may be used as appropriate models. There are, however, two major provisos that compromise this generalisation. Firstly, the endocrine function of placenta represents a complex interaction between cytotrophoblast, syncytiotrophoblast and multiple regulators, so a single cell population digested from the normal environment is unlikely to represent this. Secondly, the characterisation of primary trophoblast populations and of cell-lines is incomplete, complicating the assignment of functions to trophoblast populations. Despite these difficulties, useful information has been obtained from the available cell-lines, regardless of whether they have arisen spontaneously, been transformed in vitro, or derived from cancers in vivo.

The use of laser capture microdissection (LCM) and quantitative polymerase chain reaction to define thyroid hormone receptor expression in human ‘term’ placenta

Term 'villous' placenta consists of a heterogeneous mix of different cell types comprising the trophoblast layers, villous stroma and fetal blood vessels. The importance of using techniques which allow investigation of pure populations of cells has been increasingly recognised. We demonstrate the use of laser capture microdissection (LCM) in combination with quantitative RT-PCR (QPCR) to assess the relative expression of mRNAs encoding the major thyroid hormone receptor (TR) isoforms (alpha1, alpha2 and beta1) in trophoblasts (syncytiotrophoblast and cytotrophoblast layers) compared with stromal cells in human term placenta. Highly reproducible results for each gene were obtained for each placental sample studied (n = 6). There was significantly less mRNA encoding TRalpha1 (68%; p = 0.05) and TRbeta1 (40%; p = 0.03) in the trophoblast layer compared to the heterogeneous stromal cells. However, there was no significant difference in TRalpha2 mRNA expression between the two groups of cells.

CONCLUSION

LCM with QPCR can precisely locate and accurately quantify mRNA expression in specific cell populations from placental tissue.

Trophoblast stem cells differentiate in vitro into invasive trophoblast giant cells

Trophoblast cells are characterized by an invasive behavior into the surrounding uterine tissue. In rodents, an early peri-/endovascular type of invasion exerted by trophoblast giant cells can be distinguished from a late interstitial type carried out by glycogen trophoblast cells. Analysis of the molecular mechanisms of trophoblast invasion has been hampered, however, by the complex temporal and spatial patterns of invasion. We utilized trophoblast stem (TS) cell lines to study trophoblast invasion in vitro and to establish a model that facilitates investigation of this process on the molecular level. Our results showed that trophoblast giant cells that differentiate from TS cells in vitro are capable of penetrating a reconstituted basement membrane matrix. Consequently, invasion rates were increased in various giant cell differentiation-promoting conditions. We also derived TS cell lines that are homozygous for a mutation of the Hand1 transcription factor. The Hand1-/- TS cells showed reduced levels of giant cell differentiation and exhibited an approximately 50% decrease in invasion rates. In summary, trophoblast giant cells that differentiate from TS cells in vitro recapitulate the invasive capacity of normal trophoblast cells in vivo. The TS cell system is a valuable tool to identify and quantitatively study regulators of trophoblast invasion.

Innovative techniques and applications in histochemistry and cell biology

Recent studies documenting novel histochemical methods and applications in cell biology and in other areas of the life sciences have again rendered insights into structure and functions of tissues, cells, and cellular components to the level of proteins and genes. Particularly, sophisticated microscopic techniques have proved to be able to significantly advance our knowledge. Findings of recent investigations representing this progress are summarized in the present review.

Progress in focus: recent advances in histochemistry and cell biology

Advances in histochemical and cell biological techniques enable increasingly refined investigations into the cellular and subcellular distribution of specific molecules and into their role in dynamic processes; thus progress in these fields complements the growing knowledge in genomics and proteomics. The present review summarizes recent technical progress and novel applications.