Effects of low molecular weight heparin and heparin-binding epidermal growth factor on human trophoblast in first trimester

Prophylactic low-molecular-weight heparin in women with thrombophilia undergoing in vitro fertilization

OBJECTIVE

To verify whether low-molecular-weight heparin (LMWH) could increase pregnancy rates and/or decrease abortion rates in women with thrombophilia undergoing assisted reproduction cycles.

METHODS

Cross-sectional study with patients undergoing in vitro fertilization (IVF) (N = 104). Women without thrombophilia (control group, n = 20), women with thrombophilia who did not receive LMWH (untreated group, n = 30), and women with thrombophilia, treated with daily enoxaparin from the day of embryo transfer until week 36 of gestation (treated group, n = 54). All women underwent controlled ovarian hyperstimulation. IVF was performed by intracytoplasmic sperm injection, and embryos were transferred on day 3. Pregnancy was detected by β-human chorionic gonadotropin (biochemical pregnancy) and fetal heartbeat at week 5 to 6. Ongoing pregnancy was determined by ultrasound on week 12.

RESULTS

Patients in the untreated thrombophilia group presented with significantly lower ongoing pregnancy rates and live birth rates and significantly higher early pregnancy loss and abortion rates when compared with the control and the treated thrombophilia groups.

CONCLUSIONS

In women with diagnosed coagulation disorders, use of LMWH is important to avoid miscarriages.

Progress of oxidative stress in endometrium decidualization

The difficulty in maintaining the balance between oxides and antioxidants causes a phenomenon named oxidative stress. Oxidative stress often leads to tissue damage and participates in the pathogenesis of a series of diseases. Decidua provides the 'soil' for embryo implantation, and the normal decidualization shows the characteristics of strong antioxidation. Once the mechanism of antioxidant stress goes awry, it will lead to a series of pregnancy-related diseases. In recent years, more and more studies have shown that oxidative stress is involved in pregnancy-related diseases caused by abnormal decidualization of the endometrium. In order to have a more comprehensive understanding of the role of oxidative stress in decidual defect diseases, this paper reviews the common decidual defect diseases in conjunction with relevant regulatory molecules, in order to arouse thinking about the importance of oxidative stress, and to provide more theoretical basis for the aetiology of decidual defects.

Temporal changes of the endothelin system in human cytotrophoblasts during the first trimester of pregnancy

The first trimester of pregnancy is characterized by continuous proliferation, invasion and differentiation of cytotrophoblasts. These processes are precisely controlled both, in space and time by molecules such as endothelin-1 (ET-1). ET-1 is expressed in human first trimester trophoblast and is known to stimulate cytotrophoblast proliferation through endothelin A and B receptor subtypes (ET(A) and ET(B)), and cytotrophoblast invasion through ET(B). However, temporal changes of the ET system during the first trimester of pregnancy have not been previously studied. This study tested the hypothesis that ET-1 release, ET(A) and ET(B) expression are increased towards the end of the first trimester of pregnancy (weeks 10-12 vs. weeks 6-9), resulting in increased cytotrophoblast proliferation and invasion. Tissue samples were obtained from 17 surgical pregnancy interruptions (week 6-9: n=9; week 10-12: n=8). After cytotrophoblast isolation, the invasive and proliferative phenotypes were immune-separated by an alpha(6)-integrin antibody. Both proliferative and invasive cytotrophoblasts were cultured separately on plastic or Matrigel for 24 h. ET-1 release into the culture medium of both cytotrophoblast subtypes was measured by radioimmunoassay. ET(A) and ET(B) mRNA expression was measured by RT-PCR, and the ET-1 effect on cytotrophoblast proliferation and invasion was determined using proliferation and invasion assays, respectively. ET-1 release increased from early to late first trimester of pregnancy in both proliferative (1.8-4.5 fold) and invasive cytotrophoblasts (9.3-28 fold), especially when cultured on Matrigel. This was paralleled by less ET(B) mRNA on invasive cytotrophoblasts independent of the time period in first trimester, whereas ET(A) expression was similar on proliferative an invasive cytotrophoblasts. Proliferation and invasion of cytotrophoblasts under control conditions decreased from early to late first trimester. ET-1 stimulated both processes at both periods with the most pronounced effect (7-fold) on invasion in late first trimester. The ET-1/ET-receptor system changes between weeks 6-9 and 10-12 in pregnancy. Our data suggest an autocrine and endocrine ET-1 effect, which is stronger in late than in early first trimester of pregnancy paralleled by different stimulatory effects on trophoblast invasion and proliferation. In general, this suggests time as an additional effector of the critical processes governing placental development in the first trimester of human pregnancy.

Molecular actions of heparin and their implications in preventing pre-eclampsia

Pre-eclampsia, a hypertensive disorder of pregnancy, continues to be a significant cause of global maternal morbidity. Low-dose aspirin remains the only standard-of-care prophylactic therapy for preventing pre-eclampsia, but is limited in efficacy. Heparin and its derivatives may further enhance the efficacy of aspirin therapy to prevent pre-eclampsia, but the mechanisms mediating this augmentative effect are not known. Although heparin is an anticoagulant agent, it also possesses many anticoagulant-independent properties that may be relevant in the prevention of pre-eclampsia, including effects on placental, vascular and inflammatory function. This review summarizes the non-anticoagulant properties of heparin, and extrapolates how these actions may influence the trajectory of pre-eclampsia pathogenesis as a means of pathway-specific therapy.

Enhancement of trophoblast differentiation and survival by low molecular weight heparin requires heparin-binding EGF-like growth factor

STUDY QUESTION

Does low molecular weight heparin (LMWH) require heparin-binding epidermal growth factor (EGF)-like growth factor (HBEGF) signaling to induce extravillous trophoblast differentiation and decrease apoptosis during oxidative stress?

SUMMARY ANSWER

LMWH increased HBEGF expression and secretion, and HBEGF signaling was required to stimulate trophoblast extravillous differentiation, increase invasion in vitro and reduce trophoblast apoptosis during oxidative stress.

WHAT IS KNOWN ALREADY

Abnormal trophoblast differentiation and survival contribute to placental insufficiency syndromes, including preeclampsia and intrauterine growth restriction. Preeclampsia often manifests as a pro-thrombotic state, with unsuccessful transformation of the spiral arteries that reduces oxygen supply and can produce placental infarction. LMWH improves placental function by increasing blood flow. Recent data suggest that the actions of LMWH transcend its anti-coagulative properties, but the molecular mechanism is unknown. There is evidence that LMWH alters the expression of human HBEGF in trophoblast cells, which regulates human trophoblast pathophysiology. HBEGF, itself, is capable of increasing trophoblast survival and invasiveness.

STUDY DESIGN, SIZE, DURATION

First-trimester placental explants and the HTR-8/SVneo cell line, established using extravillous trophoblast outgrowths from first-trimester villous explants, were treated in vitro with LMWH to examine the effects on HBEGF signaling and trophoblast function under normal physiological and pathological conditions. A highly specific antagonist of HBEGF and other inhibitors of HBEGF downstream signaling were used to determine the relationship between LMWH treatment and HBEGF.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Placental tissues (n = 5) were obtained with IRB approval and patient consent from first-trimester terminations. Placental explants and HTR-8/SVneo cells were cultured on plastic or Matrigel™ and treated with a therapeutic dose of LMWH (Enoxaparin; 10 IU/ml), with or without CRM197, pan Erb-B2 Receptor Tyrosine Kinase (ERBB) inhibitor, anti-ERBB1 or ERBB4 blocking antibodies, or pretreatment of cells with heparitinase I. Extravillous differentiation was assessed by immunocytochemistry to determine the relative levels of integrins α6β4 and α1β1. Trophoblast invasiveness was assessed in villous explants by measuring outgrowth from villous tips cultured on Matrigel, and by invasion assays with HTR-8/SVneo cells cultured on Matrigel-coated transwell insert. Placental explants and HTR-8/SVneo cells were exposed to oxidative stress in a hypoxia-reoxygenation (H-R) model, measuring cell death by TUNEL assay, caspase 3 cleavage, and BCL-2α expression.

MAIN RESULTS AND THE ROLE OF CHANCE

LMWH induced extravillous differentiation, according to trophoblast invasion assays and integrin (α6β4-α1β1) switching. Treatment with LMWH rescued cytotrophoblasts and HTR-8/SVneo cells from apoptosis during exposure to reoxygenation injury, based on TUNEL, caspase 3 cleavage and BCL-2α expression. Experiments using CRM197, ERBB1 and ERBB4 blocking antibodies, pan-ERBB inhibitor and removal of cell surface heparin demonstrated that the effects of LMWH on trophoblast invasion and survival were dependent upon HBEGF signaling.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

The primary limitation of this study was the use of only in vitro experiments. Patient demographics from elective terminations were not available.

WIDER IMPLICATIONS OF THE FINDINGS

These data provide new insights into the non-coagulation-related aspects of perinatal LMWH treatment in the management of placental insufficiency disorders.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by grants from the National Institutes of Health (HD071408 and HL128628), the March of Dimes, and the W. K. Kellogg Foundation. There were no conflicts or competing interests.

Modulation of antiphospholipid antibodies-induced trophoblast damage by different drugs used to prevent pregnancy morbidity associated with antiphospholipid syndrome

PROBLEM

Women with antiphospholipid antibodies (aPLs) present a risk of pregnancy morbidity (PM), vascular thrombosis (VT), or both (PM/VT). aPLs affect trophoblast function, and the aim of this study was to determine the modulation of this aPL-induced damage by different drugs.

METHOD OF STUDY

IgG was obtained from women with PM and PM/VT positive to aPLs. Binding of IgG to trophoblastic cells, proliferation, mitochondrial membrane integrity, and trophoblast invasion were assessed. The effect of enoxaparin, aspirin, and aspirin-triggered lipoxin (ATL) were evaluated as well as signal transducer and activator of transcription 3 (STAT3) phosphorylation.

RESULTS

IgG from women with aPLs strongly binds to trophoblastic cells. Integrity of mitochondrial membrane was reduced, and proliferation was increased by IgG-PM/VT. Both IgG-PM and IgG-PM/VT decreased trophoblast invasion, which was restored by enoxaparin, aspirin, and ATL. IgG-PM triggered reduction in STAT3 phosphorylation.

CONCLUSION

Some drugs used to prevent aPL-induced PM modulated the alteration of trophoblast function.

The Prevalence of Thrombophilia in Women With Recurrent Fetal Loss and Outcome of Anticoagulation Therapy for the Prevention of Miscarriages

OBJECTIVE

To estimate the prevalence of thrombophilia in women with recurrent miscarriages and to assess the effect of antithrombotic therapy.

DESIGN

A retrospective cohort study between the years 2004 and 2010.

SETTING

A hypercoagulation community clinic in northern Israel.

PATIENTS

Four hundred ninety pregnant women referred for thrombophilia screening.

MAIN OUTCOME MEASURES

Screening results for thrombophilia and antithrombotic treatment with enoxaparin, aspirin, or both and pregnancy outcomes.

RESULTS

The most common thrombophilia in our study group was factor V Leiden mutation with a prevalence of 20.9% followed by protein S deficiency with a prevalence of 19%. Live birth rate was higher in the group of women who received enoxaparin regardless of whether a specific thrombophilia could be found. This finding was more pronounced in women who had ≥4 miscarriages.

CONCLUSION

The prevalence of thrombophilia was higher in our study group than in the general population. Furthermore, treatment with enoxaparin might improve the rate of live births in women with or without evidence of thrombophilia, especially in women with ≥4 miscarriages.

Aspirin and low-molecular weight heparin combination therapy effectively prevents recurrent miscarriage in hyperhomocysteinemic women

The management of recurrent pregnancy loss (RPL) still remains a great challenge, and women with polycystic ovarian syndrome (PCOS) are at a greater risk for spontaneous abortion. Treatment with low-molecular-weight heparin (LMWH) has become an accepted treatment option for women with RPL; however, the subgroup of women, who are likely to respond to LMWH, has not been precisely identified. The present study evaluated the efficacy of LMWH with reference to PCOS and associated metabolic phenotypes including hyperhomocysteinemia (HHcy), insulin resistance (IR) and obesity. This prospective observational study was conducted at Institute of Reproductive Medicine, Kolkata, India. A total of 967 women with history of 2 or more consecutive first trimester abortions were screened and 336 were selected for the study. The selected patients were initially divided on the basis of presence or absence of PCOS, while subsequent stratification was based on HHcy, IR and/or obesity. The subjects had treatment with aspirin during one conception cycle and aspirin-LMWH combined anticoagulant therapy for the immediate next conception cycle, if the first treated cycle was unsuccessful. Pregnancy salvage was the sole outcome measure. The overall rate of pregnancy salvage following aspirin therapy was 43.15%, which was mostly represented by normohomocysteinemic women, while the salvage rate was lower in the HHcy populations irrespective of the presence or absence of PCOS, IR, or obesity. By contrast, aspirin-LMWH combined therapy could rescue 66.84% pregnancies in the aspirin-failed cases. Logistic regression analyses showed that HHcy remained a significant factor in predicting salvage rates in the PCOS, IR, and obese subpopulations controlled for other confounding factors. With regard to pregnancy salvage, combined anticoagulant therapy with aspirin and LMWH conferred added benefit to those with HHcy phenotype.

The tyrosine phosphatase SHP-1 negatively regulates cytotrophoblast proliferation in first-trimester human placenta by modulating EGFR activation

Insulin-like growth factors (IGFs) influence placental cell (cytotrophoblast) kinetics. We recently reported that the protein tyrosine phosphatase (PTP) SHP-2 positively regulates IGF actions in the placenta. In other systems, the closely related PTP, SHP-1, functions as a negative regulator of signaling events but its role in the placenta is still unknown. We examined the hypothesis that SHP-1 negatively regulates IGF actions in the human placenta. Immunohistochemical (IHC) analysis demonstrated that SHP-1 is abundant in cytotrophoblast. SHP-1 expression was decreased in first-trimester placental explants using siRNA; knockdown did not alter IGF-induced proliferation but it significantly enhanced proliferation in serum-free conditions, revealing that placental growth is endogenously regulated. Candidate regulators were determined by using antibody arrays, Western blotting, and IHC to examine the activation status of multiple receptor tyrosine kinases (RTKs) in SHP-1-depleted explants; amongst the alterations observed was enhanced activation of EGFR, suggesting that SHP-1 may interact with EGFR to inhibit proliferation. The EGFR tyrosine kinase inhibitor PD153035 reversed the elevated proliferation seen in the absence of SHP-1. This study demonstrates a role for SHP-1 in human trophoblast turnover and establishes SHP-1 as a negative regulator of EGFR activation. Targeting placental SHP-1 expression may provide therapeutic benefits in common pregnancy conditions with abnormal trophoblast proliferation.

Emerging nonanticoagulant role of low molecular weight heparins on extravillous trophoblast functions and on heparin binding-epidermal growth factor and cystein-rich angiogenic inducer 61 expression

OBJECTIVE

To examine the effects of low molecular weight heparins (LMWHs) on extravillous trophoblast (EVTC) invasiveness and on EVTC expression/secretion of heparin binding-EGF (HB-EGF) and cystein-rich angiogenic inducer 61 (Cyr61), both of which are involved in the process of EVTC invasion. Furthermore, to investigate the intracellular DNA binding activity of activator protein (AP)-1.

DESIGN

Experimental study.

SETTING

Department of Obstetrics Gynecology, Università Cattolica del Sacro Cuore, Rome, Italy.

PATIENT(S)

Cultures of primary EVTC cells isolated from patients with first trimester unexplained recurrent miscarriage.

INTERVENTION(S)

The effects of LMWHs on EVTC invasiveness were examined by an in vitro matrigel invasion assay. Matrix metalloprotease-2 activity (MMP-2) was examined by gelatin zimography. HB-EGF and Cyr61 expression and secretion were studied by Western blot analysis and ELISA assay. AP-1 activity was measured through a multiwell colorimetric assay.

MAIN OUTCOME MEASURE(S)

The EVTC invasiveness, the expression/secretion of HB-EGF and Cyr61 proteins, and the AP-1 DNA binding activity in the presence of increasing concentrations of LMWHs were investigated.

RESULT(S)

Both LMWHs, and primarily tinzaparin, increased EVTC invasiveness, by enhancing the MMP-2 proteolytic activity, and induced the expression/secretion of HB-EGF and Cyr61 in EVTC. This effect was mediated by an increased DNA binding activity of AP-1.

CONCLUSION(S)

Both LMWHs are able to promote EVTC development because they are able to stimulate the EVTC invasive properties. Our results may provide a possible biological rationale for the clinical use of LMWH for placental-mediated pregnancy complications unrelated to prothrombotic disorders.

Comparison of uterine artery Doppler in pregnant women with thrombophilia treated by LMWHs and without thrombophilia

OBJECTIVE

The aim of this study was to use uterine artery Doppler ultrasonography to investigate the cases of women with thrombophilia who used LMWH during the 18-22-week period of gestation.

METHODS

This retrospective study was conducted at our university between January 2005 and July 2010. 64 patients were treated with low-dose LMWHs (enoxaparine 40 mg) from the beginning of pregnancy until 36 weeks of gestation. Fifty control subjects were also included in this study. Transabdominal ultrasound examination and bilateral uterine artery Doppler measurements pulsatility index (PI), resistive index (RI), and systole/diastole measurement (S/D) were performed during the 18-22-weeks period of gestation.

RESULTS

No significant differences were found between the groups with respect to maternal age or gestational age at the time of uterine artery Doppler. However, the mean PI (1.07 ± 0.46 for LMWH group and 0.91 ± 0.31 for control, p = 0.036) and the mean RI (0.59 ± 0.12 for LMWH group and 0.54 ± 0.10 for control, p = 0.021) were significantly higher in the trombophilia group.

CONCLUSION

Women with trombophilia still have an increased mean PI and RI, as determined by uterine artery Doppler ultrasonography during the 18-22-week period of gestation, even if they use LMWH.