Strong inhibitory effect of pre-eclampsia serum on angiogenesis detected in vitro by human cell-based angiogenesis tests

Immunometric and functional measurement of endogenous vasoinhibin in human sera

Introduction

Circulating levels of the antiangiogenic protein vasoinhibin, a fragment of prolactin, are of interest in vasoproliferative retinopathies, preeclampsia, and peripartum cardiomyopathy; however, it is difficult to determine the circulating levels of vasoinhibin due to the lack of quantitative assays.

Methods

This study used human serum samples to assess the concentration and bioactivity of vasoinhibin using a novel enzyme-linked immunosorbent assay (ELISA) for human vasoinhibin, which employs an anti-vasoinhibin monoclonal antibody, a human umbilical vein endothelial cell (HUVEC) proliferation assay, and a chick chorioallantoic membrane (CAM) angiogenesis assay.

Results

Serum samples from 17 pregnant women without (one group) and with preeclampsia and pregnancy induced hypertension (another group) demonstrated endogenous vasoinhibin concentrations in the range of 5-340 ng/ml. Immunoactive vasoinhibin levels were significantly higher in preeclampsia serum compared to healthy pregnancy serum (mean 63.09 ± 22.15 SD vs. 19.67 ± 13.34 ng/ml, p = 0.0003), as was the bioactive vasoinhibin level as determined by the HUVEC proliferation assay (56.12 ± 19.83 vs. 13.38 ± 4.88 ng/ml, p < 0.0001). There was a correlation between the concentration of vasoinhibin measured by ELISA and the HUVEC proliferation assay (Pearson r = 0.95, p < 0.0001). Healthy serum demonstrated a proangiogenic effect in the CAM assay (p < 0.05, compared to control), while serum from preeclamptic patients demonstrated an antiangiogenic effect (p < 0.05 vs. control), as did recombinant human vasoinhibin and a synthetic circular retro-inverse vasoinhibin analogue (CRIVi45-51). The antiangiogenic effects in the CAM assay and the inhibition of HUVEC proliferation were abolished by addition of the ELISA anti-vasoinhibin monoclonal antibody, but not by mouse IgG.

Discussion

These results demonstrate the first quantitation of endogenous vasoinhibin in human sera and the elevation of it levels and antiangiogenic activity in sera from women with preeclampsia. The development and implementation of a quantitative assay for vasoinhibin overcomes a long-standing barrier and suggests the thorough clinical verification of vasoinhibin as a relevant biomarker.

Long noncoding TUG1 promotes angiogenesis of HUVECs in PE via regulating the miR-29a-3p/VEGFA and Ang2/Tie2 pathways

BACKGROUND

Preeclampsia (PE) is a pregnancy-specific disease that is associated with oxidative stress-induced endothelial dysfunction. Long noncoding RNAs (lncRNAs) are related to PE progression. The purpose is to study whether lncRNA taurine-upregulated gene 1 (TUG1) takes part in endothelial dysfunction in PE.

METHODS

The placenta tissues were collected from PE patients and normal subjects. Human umbilical vein endothelial cells (HUVECs) were suffered from hypoxia-reoxygenation (H/R). TUG1, miR-29a-3p and vascular endothelial growth factor A (VEGFA) were detected via qRT-PCR. soluble fms-related tyrosine kinase-1 (sFLT1) and soluble endoglin (sENG) levels were detected by ELISA. Cell proliferation, migration, invasion and angiogenesis were examined via MTT, wound healing analysis, transwell and tube formation analysis. The proteins in VEGFA and angiopoietin 2 (Ang2)/tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie2) signaling were measured by western blot. The binding relationship was analyzed via Starbase, Jefferson and dual-luciferase reporter analysis.

RESULTS

TUG1 and VEGFA levels were downregulated, and levels of miR-29a-3p, sFLT1 and sENG were increased in PE patients. TUG1 abundance was reduced in H/R-stimulated HUVECs, and TUG1 overexpression increased proliferation, migration, invasion and angiogenesis, and activated the VEGFA and Ang2/Tie2 signaling in H/R-stimulated HUVECs. TUG1 sponged miR-29a-3p, and miR-29a-3p overexpression reversed the function of TUG1 on H/R-induced HUVECs dysfunction. MiR-29a-3p knockdown attenuated H/R-induced inhibition of proliferation, migration, invasion, angiogenesis and activation of the VEGFA and Ang2/Tie2 signaling in HUVECs. VEGFA and Ang2 were targeted by miR-29a-3p, and VEGFA or Ang2 silence weakened the role of miR-29a-3p knockdown in H/R-caused HUVECs dysfunction.

CONCLUSION

TUG1 facilitates proliferation, migration, invasion and angiogenesis in H/R-stimulated HUVECs via activating the VEGFA and Ang2/Tie2 signaling by regulating miR-29a-3p.

Angiogenic Effect of Pravastatin Alone and with Sera from Healthy and Complicated Pregnancies Studied by in vitro Vasculogenesis/Angiogenesis Assay

OBJECTIVE

To determine the direct effect of pravastatin on angiogenesis and to study the interaction between pravastatin and maternal sera from women with early- or late-onset pre-eclampsia (PE), intrauterine growth restriction, or healthy pregnancy.

METHODS

We collected 5 maternal serum samples from each group. The effect of pravastatin on angiogenesis was assessed with and without maternal sera by quantifying tubule formation in a human-based in vitro assay. Pravastatin was added at 20, 1,000, and 8,000 ng/mL concentrations. Concentrations of angiogenic and inflammatory biomarkers in serum and in test medium after supplementation of serum alone and with pravastatin (1,000 ng/mL) were measured.

RESULTS

Therapeutic concentration of pravastatin (20 ng/mL) did not have significant direct effect on angiogenesis, but the highest concentrations inhibited angiogenesis. Pravastatin did not change the levels of biomarkers in the test media. There were no changes in angiogenesis when therapeutic dose of pravastatin was added with maternal sera, but there was a trend to wide individual variation towards enhanced angiogenesis, particularly in the early-onset PE group.

CONCLUSIONS

At therapeutic concentration, pravastatin alone or with maternal sera has no significant effect on angiogenesis, but at high concentrations the effect seems to be anti-angiogenic estimated by in vitro assay.

Therapeutic doses of metformin do not have impact on angiogenesis in presence of sera from pre-eclamptic, IUGR and healthy pregnancies

Recent evidence suggests that metformin may prevent pre-eclampsia by reverting the angiogenic imbalance in maternal sera. In this study, we investigated effect of metformin on angiogenesis by quantifying tubule formation in a human-based in vitro test with co-culture of human adipose stromal cell (hASC) and human umbilical vein endothelial cell (HUVEC). A total of 20 pregnant women were recruited in the study. Serum samples were obtained from women with early- and late-onset pre-eclampsia and from women with pregnancies complicated by intrauterine growth restriction (IUGR) without pre-eclampsia (N = 5 in each of the three groups). Serum samples from women with healthy pregnancies served as controls (N = 5). The direct effect of metformin on angiogenesis was first assessed without maternal sera. Secondly, we investigated the impact of metformin on angiogenesis in the present of maternal sera. Metformin was used at 5, 50 and 600 µg/ml concentrations. Angiogenic and inflammatory biomarkers in maternal sera were analyzed by immunoassays. When the direct effect of metformin was studied, the two lowest concentrations of metformin did not affect tubule formation (angiogenesis), but the highest concentration inhibited angiogenesis. When metformin was supplemented at therapeutic concentrations of 5 and 50 µg/ml along with serum samples, there was no change in tubule formation in comparison to maternal sera alone. However, strong inhibitory effect on tubule formation was observed in all groups with the highest, non-therapeutic (600 µg/ml), concentration of metformin.

Pericytes Contribute to Dysfunction in a Human 3D Model of Placental Microvasculature through VEGF-Ang-Tie2 Signaling

Placental vasculopathies are associated with a number of pregnancy-related diseases, including pre-eclampsia (PE)-a leading cause of maternal-fetal morbidity and mortality worldwide. Placental presentations of PE are associated with endothelial dysfunction, reduced vessel perfusion, white blood cell infiltration, and altered production of angiogenic factors within the placenta (a candidate mechanism). Despite maintaining vascular quiescence in other tissues, how pericytes contribute to vascular growth and signaling in the placenta remains unknown. Here, pericytes are hypothesized to play a detrimental role in the pathogenesis of placental vascular growth. A perfusable triculture model is developed, consisting of human endothelial cells, fibroblasts, and pericytes, capable of recapitulating growth and remodeling in a system that mimics inflamed placental microvessels. Placental pericytes are shown to contribute to growth restriction of microvessels over time, an effect that is strongly regulated by vascular endothelial growth factor and Angiopoietin/Tie2 signaling. Furthermore, this model is capable of recapitulating essential processes including tumor necrosis factor alpha (TNFα)-mediated vascular leakage and leukocyte infiltration, both important aspects associated with placental PE. This placental vascular model highlights that an imbalance in endothelial-pericyte crosstalk can play a critical role in the development of vascular pathology and associated diseases.

Angiogenic capacity in pre-eclampsia and uncomplicated pregnancy estimated by assay of angiogenic proteins and an in vitro vasculogenesis/angiogenesis test

OBJECTIVE

The purpose of the study was to determine the angiogenic capacity of sera in early and late pregnancy and in umbilical blood serum after childbirth, and to define how angiogenic properties assessed in a functional in vitro test are related to individual angiogenic proteins in six women with pre-eclampsia and in six healthy pregnant controls.

METHODS

Maternal first and third trimester serum samples, and umbilical blood samples after childbirth, were tested in an in vitro human adipose stromal cell-human umbilical vein endothelial cell (hASC-HUVEC) vasculogenesis/angiogenesis assay. The angiogenic properties of the samples were measured by quantifying tubule formation. Concentrations of total placental growth factor (PlGF), total vascular endothelial growth factor (VEGF), soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng) were determined by immunoassay.

RESULTS

First-trimester maternal sera of both groups had a stimulatory effect on angiogenesis in vitro and levels of angiogenic proteins did not differ between the groups. Third-trimester maternal sera in the pre-eclampsia group had an inhibitory effect on tubule formation, while those from normal pregnancies remained stimulatory. Compared with the first trimester there was a significant change in the concentrations of angiogenic proteins toward an anti-angiogenic state in pre-eclampsia. Umbilical blood serum exhibited strong anti-angiogenic effects without a significant difference between groups.

CONCLUSIONS

Third-trimester serum of pre-eclamptic patients is anti-angiogenic. This phenomenon is not yet present in the first trimester. Umbilical blood serum shows inhibitory effects on angiogenesis after normal as well as pre-eclamptic pregnancy.

Elucidating the Pathogenesis of Pre-eclampsia Using In Vitro Models of Spiral Uterine Artery Remodelling

PURPOSE OF REVIEW

The aim of the study is to perform a critical assessment of in vitro models of pre-eclampsia using complementary human and cell line-based studies. Molecular mechanisms involved in spiral uterine artery (SUA) remodelling and trophoblast functionality will also be discussed.

RECENT FINDINGS

A number of proteins and microRNAs have been implicated as key in SUA remodelling, which could be explored as early biomarkers or therapeutic targets for prevention of pre-eclampsia. Various 2D and 3D in vitro models involving trophoblast cells, endothelial cells, immune cells and placental tissue were discussed to elucidate the pathogenesis of pre-eclampsia. Nevertheless, pre-eclampsia is a multifactorial disease, and the mechanisms involved in its pathogenesis are complex and still largely unknown. Further studies are required to provide better understanding of the key processes leading to inappropriate placental development which is the root cause of pre-eclampsia. This new knowledge could identify novel biomarkers and treatment strategies.