Endothelial cell proliferation is suppressed by plasma but not serum from women with preeclampsia

OBJECTIVES

Evidence has been sought for a circulating factor derived from the placenta that suppresses endothelial cell proliferation and hence contributes to the maternal endothelial cell disturbances of preeclampsia.

STUDY DESIGN

The effects of sera and plasmas from women with proteinuric preeclampsia and from matched normal pregnant control women on endothelial cell proliferation were compared. The recovery of endothelial cell inhibitory activity from syncytiotrophoblast microvesicles added to male blood and prepared as plasma or serum was determined to investigate the possible placental origin of the inhibitory factor.

RESULTS

Sera from women with preeclampsia did not inhibit endothelial cell proliferation. In contrast, plasma from preeclamptic women significantly suppressed endothelial cell growth at 20% dilution compared with controls, and suppression was more pronounced in severe preeclampsia. The inhibitory activity of syncytiotrophoblast microvesicles added to blood could not be recovered from serum, only from plasma, which may explain why there was no suppression with sera from preeclamptic women.

CONCLUSIONS

These results confirm that there is a blood-borne endothelial cell suppressive factor in preeclampsia that may be derived from the placenta.

Improvements in computerized fetal heart rate analysis antepartum

The continued development of a computerised system for measuring the pattern of the antepartum fetal heart rate (FHR) is described. Previous work had established that measurement of FHR variation objectively detects chronic fetal hypoxaemia and the onset of metabolic acidaemia antepartum. The normal centiles were calculated for the amplitude of long-term FHR variation, in episodes of high and low variation, week by week from 24-42 weeks gestation. Reference to these (automatically by the computer) improved discrimination between normal and questionable records in 38% of records, with a small saving of time. Two types of sinusoidal rhythm were described (slow, 1 in 2-5 minutes, incidence 0.16% of subjects; and faster, 2-5 per minute, incidence 0.025%) with methods for their detection. Both may be of sufficient amplitude to induce an episode of high FHR variation. The different effects of maternal steroid (betamethasone or dexamethasone) administration of FHR variation were compared, and the clinical consequences considered. The frequency distribution of basal FHR in normal and abnormal records was measured, and the effects on basal FHR outside the normal range (120-160 bpm) on FHR variation described. Adjustment of the FHR baseline was undertaken when, exceptionally, large abrupt changes in heart rate occurred during a record. The duration and frequency of FHR record acquisition in clinical practice were reviewed, and new policies recommended. With adequate safeguards, measurement by a computer offers reliable objective information from which fetal health may be assessed, more objectively and accurately than by visual inspection.

The angiotensin sensitivity test and low-dose aspirin are ineffective methods to predict and prevent hypertensive disorders in nulliparous pregnancy

OBJECTIVE

Our purpose was to assess the efficiency of the angiotensin sensitivity test as a predictive test for preeclampsia and the effectiveness of low-dose aspirin to prevent preeclampsia when commenced at 28 weeks' gestation in angiotensin II-sensitive women.

STUDY DESIGN

A total of 495 healthy nulliparous women underwent the angiotensin sensitivity test at 28 weeks' gestation. The angiotensin II-sensitive women were randomized to 60 mg of aspirin or placebo as a subset of a large multicenter, randomized, controlled trial of low-dose aspirin therapy in pregnancy. Assessment of the efficiency of the angiotensin sensitivity test and low-dose aspirin in pregnancy was performed after detailed review of case notes after delivery. The Oxford definition of preeclampsia was used. This includes women without proteinuria but requires blood pressure increments that have been validated to bias the selection to primigravid women.

RESULTS

Five women had proteinuric preeclampsia in the angiotensin II-sensitive group randomized to aspirin compared with none in the group randomized to placebo. Overall, 11 (25%) of the women randomized to aspirin had preeclampsia compared with four (11%) randomized to placebo (p < 0.05, not significant). The positive and negative predictive values for the angiotensin sensitivity test were 19% and 87%, respectively.

CONCLUSION

The angiotensin sensitivity test is not an effective screening test for preeclampsia, and low-dose aspirin does not prevent preeclampsia when commenced at 28 weeks' gestation in angiotensin II-sensitive women.

Corticotrophin-releasing hormone and corticotrophin-releasing hormone binding protein in normal and pre-eclamptic human pregnancies

OBJECTIVE

To measure the plasma levels of corticotrophin-releasing hormone and corticotrophin-releasing hormone binding protein in normal pregnancy and in pregnancies complicated by pre-eclampsia.

SETTING

John Radcliffe Hospital, Oxford and St Thomas's Hospital, London.

SUBJECTS

One hundred and twenty pregnant women sampled prospectively throughout gestation, of whom 91 experienced a normal pregnancy and eight developed pre-eclampsia; in a second study, 10 women with severe pre-eclampsia, presenting at a range of gestational ages, were sampled once and compared with appropriately matched normal pregnant women.

MAIN OUTCOME MEASURE

Plasma levels of corticotrophin-releasing hormone determined by immunoradiometric assay. Plasma levels of corticotrophin-releasing hormone binding protein measured by direct radioimmunoassay.

RESULTS

In the prospective study, plasma samples from women with pre-eclampsia exhibited higher (390.2 versus 292.7 pmol/l at 36 weeks) levels of corticotrophin-releasing hormone and significantly lower (5.24 versus 8.14 nmol/l at 36 weeks, P < 0.002) levels of corticotrophin-releasing hormone binding protein than normal controls. In the second, single time point study a significant elevation in CRH (P < 0.002) and reduction in CRH-BP (P < 0.001) was found in pre-eclamptic pregnancies compared with controls.

CONCLUSIONS

In human pregnancies complicated by pre-eclampsia there is an elevated level of corticotrophin releasing hormone whilst there is less corticotrophin-releasing hormone binding protein; therefore there is a net increase in free potentially bioactive hormone which may play a role in the pathology of the disease.

Expression of TAP1 by human trophoblast

Successful placentation in the human is dependent on the trophoblast evading recognition and destruction by the maternal immune system. However, invasive cytotrophoblast express HLA-G which may be able to present peptide to T cells. Transporter proteins are essential for peptide presentation and major histocompatibility complex (MHC) class I assembly. We have determined their expression by trophoblast in relation to HLA-G, using immunohistochemistry. Anti-transporter protein antibody (TAP1) labeling closely paralleled that of MHC class I, but the intensity of its expression was much greater on the HLA-G+ extravillous cytotrophoblast than any other fetal or maternal tissue in the first trimester and at term. This suggests that the extravillous cytotrophoblast are very actively assembling MHC class I antigens with peptides. However, expression of MHC class I by the cytotrophoblast was not correspondingly elevated. This pattern could result from HLA-G being shed from the surface of the trophoblast, a process which may play a central role in protecting the fetus from maternal immune attack.

Platelet intracellular free calcium response to arginine vasopressin is similar in preeclampsia and normal pregnancy

OBJECTIVE

Our purpose was to compare the effect of arginine vasopressin stimulation on platelet free intracellular calcium levels in normal pregnancy, incipient preeclampsia, and established preeclampsia.

STUDY DESIGN

Cross-sectional and prospective observational study designs were used. Platelet free intracellular calcium was measured by flow cytometry in 10 nonpregnant female volunteers, 10 women with established preeclampsia and their normal pregnant matched controls, and 64 normal pregnant women at 28 weeks' gestation. All pregnant women were nulliparous.

RESULTS

Increased response to arginine vasopressin stimulation was observed in nonpregnant compared with pregnant women (p < 0.001). No differences were observed between women with normal pregnancy, incipient preeclampsia, or established preeclampsia.

CONCLUSION

The platelet intracellular free calcium response to arginine vasopressin is not a feature of incipient or established preeclampsia. Therefore, in contrast to a previous report, it does not appear to have value as a predictive test for preeclampsia.

Interleukin-6, tumour necrosis factor and soluble tumour necrosis factor receptors in women with pre-eclampsia

OBJECTIVES

Generalised maternal endothelial cell dysfunction appears to be an underlying problem in pre-eclampsia presumed to be caused, directly or indirectly, by one or more circulating factors derived from the placenta. Recently it has been suggested that tumour necrosis factor (TNF) may play an important role in pre-eclampsia and contribute to endothelial activation. This study was designed to investigate this proposal.

DESIGN

Plasma TNF-alpha, IL-6 and both forms of soluble TNF receptors (p55 and p75 TNF-R) have been measured by ELISA in 31 pre-eclamptic patients and 31 pregnant controls matched for age, parity and gestational age.

RESULTS

Levels of IL-6, TNF-alpha and soluble TNF-R (p55 and p75) were significantly higher in pre-eclamptic patients, compared with age and gestation matched controls with a wide variation in levels between pre-eclamptic individuals. There was a correlation between levels of IL-6 and TNF or TNF-R and between TNF and TNF-R levels. However, when the pre-eclamptic patients were subdivided on the basis of the severity of their disease, the median values of plasma concentrations of IL-6, TNF-alpha and TNF-R were all higher in the group with lower platelet counts.

CONCLUSIONS

These new findings are consistent with the concept that the maternal syndrome of pre-eclampsia is associated with endothelial dysfunction and provide evidence that at least part of this dysfunction could arise from excessive release of TNF-alpha into the circulation.

Eclampsia in the United Kingdom

OBJECTIVES

To measure the incidence of eclampsia, establish how often it is preceded by signs of pre-eclampsia, document the morbidity associated with eclampsia, and determine the maternal case fatality rates.

DESIGN

A prospective, descriptive study of every case of eclampsia in the United Kingdom in 1992. Information was collected from reviews of hospital case notes and questionnaires to general practitioners.

SETTING

All 279 hospitals in the United Kingdom with a consultant obstetric unit.

RESULTS

Obstetricians and midwives notified 582 possible cases, and 383 were confirmed as eclampsia. The national incidence of eclampsia was 4.9/10,000 maternities (95% confidence interval 4.5 to 5.4). Most convulsions occurred despite antenatal care (70%) and within one week of the woman's last visit to a doctor or midwife (85%). Three quarters of first seizures occurred in hospital, of which 38% developed before both proteinuria and hypertension had been documented. Forty four per cent of cases occurred postpartum, more than a third (38%) antepartum, and the remainder (18%) intrapartum. Nearly one in 50 women (1.8%) died, and 35% of all women had at least one major complication. The rate of stillbirths and neonatal deaths was 22.2/1000 and 34.1/1000, respectively. Preterm eclampsia occurred more commonly antepartum and was associated with more maternal complications and fetuses that were small for gestational age, as well as with higher rates of stillbirth and neonatal mortality. Antepartum eclampsia, which was more likely to occur preterm, was associated with a higher rate of maternal complications and a higher neonatal mortality. Both factors (gestational prematurity and antepartum occurrence) contributed independently to the severity of the outcome.

CONCLUSION

Eclampsia occurs in nearly one in 2000 maternities in the United Kingdom and is associated with high maternal morbidity and fatality in cases. It may present unheralded by warning signs. Preterm and antenatal eclampsia seem to be particularly severe.

Progression of cervical intraepithelial neoplasia to cervical cancer: interactions of cytochrome P450 CYP2D6 EM and glutathione s-transferase GSTM1 null genotypes and cigarette smoking

The factors that determine progression of cervical intraepithelial neoplasia (CIN) to squamous cell carcinoma (SCC) are unknown. Cigarette smoking is an independent risk factor for cervical neoplasia, suggesting that polymorphism at detoxicating enzyme loci such as cytochrome P450 CYP2D6 and glutathione S-transferase GSTM1 may determine susceptibility to these cancers. We have studied the frequencies of genotypes at these loci in women suffering low-grade CIN, high-grade CIN and SCC. A non-cancer control group was provided by women with normal cervical histology suffering menorrhagia. Comparison of the frequency distributions of the CYP2D6 PM, HET and EM genotypes (G-->A transition at intron 3/exon 4 and base pair deletion in exon 5) revealed no significant differences between the menorrhagia and SCC groups. Frequency distributions in the menorrhagia group, however, were significantly different (P < 0.04) from those in the low- and high-grade CIN groups. Thus, the proportion of EM was significantly larger (P < 0.03) and of HET generally lower. We found that the frequency of GSTM1 null in the menorrhagia and case groups was not significantly different. Interactive effects of enzyme genotypes with cigarette smoking were studied by comparing the multinomial frequency distributions of CYP2D6 EM/GSTM1 null/smoking over mutually exclusive categories. These showed no significant differences between the menorrhagia group and SCC or low-grade CIN groups. The frequency distribution in high-grade CIN, however, was significantly different to that in the menorrhagia group and in both SCC and low-grade CIN groups. This study was identified, for the first time, an inherited characteristic in women with high-grade CIN who appear to be at reduced risk of SCC. Thus, women with CYP2D6 EM who smoke have increased susceptibility to high-grade CIN but are less likely to progress to SCC, possibly because they effectively detoxify an unidentified chemical involved in mediating disease progression.

Dexamethasone and fetal heart rate variation

OBJECTIVE

To determine the effect of maternal administration of dexamethasone on fetal heart rate and its variation.

DESIGN

Retrospective analysis of computerised data derived from cases studied over three years.

SETTING

High risk pregnancy unit, John Radcliffe Hospital, Oxford.

SUBJECTS

Twenty-eight pregnant women, at 27 to 32 weeks of gestation, to whom dexamethasone was given to accelerate pulmonary maturation in the expectation of preterm delivery.

METHODS

Dexamethasone (two doses of 12 mg intramuscularly, 12 h apart) was given on 51 occasions at weekly intervals (one to four occasions per patient). Complete data were available for cardiotocograph analysis from computerised measurement of fetal heart rate variables for two days before and four days after dexamethasone and, in 19 women, measurements of umbilical arterial flow velocity waveforms before and after dexamethasone.

RESULTS

In 10 pregnancies without fetal distress there was a highly significant (P < 0.01) transient rise in short term fetal heart rate variation after dexamethasone administration, from means (SE) 6.4 (0.28) to 9.8 (0.4) ms. In 18 pregnancies with subsequent delivery for fetal distress (abnormal fetal heart rate pattern) and high umbilical arterial resistance index [mean 0.93 (0.06 SE)], the rise in short term fetal heart rate variation was less (P < 0.01), from mean (SE) 5.4 (0.26) to 6.1 (0.48) ms. In a further case of discordant twin pregnancy, the larger twin continued to respond to dexamethasone administrations with a rise in fetal heart rate variation for five weeks; the smaller twin, with maintained tachycardia and reduced umbilical arterial end-diastolic flow velocity, failed to respond after the first two weeks.

CONCLUSION

The results show that maternal dexamethasone administration normally causes a rise in fetal heart rate variation for up to a day. This rise is reduced in pre-eclampsia or intrauterine growth retardation, associated with a reduction in umbilical flow, perhaps because of a consequential lower concentration of steroid in the fetus. The results contrast with those for betamethasone which has been reported to reduce fetal heart rate variation.

Distribution of cell adhesion molecules in decidua of early human pregnancy. An immunohistochemical study

BACKGROUND

The aim of the study was to investigate human decidua for cell adhesion molecules involved in interactions between the various different maternal and fetal cell populations, homing of the unusual intradecidual population of CD56+ lymphocytes, and organization of the decidual extracellular matrix.

EXPERIMENTAL DESIGN

First trimester human decidua from normal pregnancies was investigated immunohistochemically with antibodies against integrin subunits (alpha 1-6, alpha L, alpha M, alpha X, alpha IIb, alpha V, beta 1, beta 3, and beta 4), platelet-endothelial cell adhesion molecule, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and L-selectin.

RESULTS

Endometrial glands stained for alpha 1, alpha 2, alpha 3, alpha 5, alpha 6, alpha V, beta 1, beta 3, and beta 4, and stromal cells for alpha 1, alpha 3, alpha 5, alpha 6, alpha V, beta 1, beta 3, ICAM-1, and VCAM-1. Endothelium stained for alpha 1, alpha 2, alpha 3, alpha 4, alpha 5, alpha 6, alpha V, alpha IIb, beta 1, beta 3, and beta 4; platelet-endothelial cell adhesion molecule and ICAM-1 also were found on the endothelium of a large number of blood vessels of all types, and VCAM-1 on the endothelium of a moderate number of arterioles and venules, and a few capillaries. Weak staining for E-selectin was seen in a moderate number of arterioles and venules. Large numbers of lymphocytes stained for alpha 4, alpha L, alpha M, alpha X, beta 1, and moderate or small numbers for alpha 1, alpha 3, alpha 5, alpha v, beta 3, platelet-endothelial cell adhesion molecule, ICAM-1, and L-selectin.

CONCLUSIONS

Decidual stromal cells, like endometrial glands and endothelium, express integrins that bind basement membrane components. These integrins represent the basis for the formation of the pericellular basement membrane of these cells. They also bind certain glycoproteins that support outgrowth and attachment of the trophoblast in vitro. Vitronectin-binding integrins on endometrial glands, stromal cells, and endothelium may be involved in adhesion of the trophoblast through vitronectin on its surface. From our findings and published data it seems that adhesion of alpha 1 beta 2 (leukocyte function-associated antigen-1) on lymphocytes to ICAM-1 on the endothelium plays the most important role in the migration of CD56+ lymphocytes from the peripheral blood into the decidua. The expression of several beta 1 (VLA) integrins on lymphocytes suggests that these cells are activated, and, like the expression of ICAM-1 and VCAM-1 on stromal cells, probably contributes to their retention in the decidual stroma.

Neonatal outcome after pregnancy complicated by abnormal velocity waveforms in the umbilical artery

The neonatal outcome of 61 infants born after pregnancies complicated by absent or reversed end diastolic flow velocities (AREDFV) in the fetal umbilical artery was compared with that of 61 controls matched for gestational age born after high risk pregnancies with documented forward end diastolic flow velocities (EDFV). The AREDFV group was significantly more growth retarded, had lower platelet counts at birth, and were more likely to become significantly thrombocytopenic in the first week after birth. Owing to concerns about the possible increased risk of necrotising enterocolitis in newborn infants after AREDFV, this group was started on enteral feeds later and was more likely to receive parenteral nutrition than the EDFV group. Seven infants with AREDFV and one control infant developed necrotising enterocolitis.

Intervention debulking surgery in advanced epithelial ovarian cancer

OBJECTIVE

To study whether intervention debulking surgery improves survival in patients with advanced ovarian cancer who have bulky (> 2 cm) residual disease after primary surgery.

DESIGN

A prospective multicentre randomised study.

SETTING

Hospitals in the West Midlands.

SUBJECTS

Ovarian cancer patients with bulky residual disease after primary surgery who are considered well enough to receive cis-platinum based chemotherapy and further surgery.

METHODS

Eligible patients were randomised to receive combination chemotherapy alone or combined with intervention debulking surgery.

MAIN OUTCOME MEASURE

Survival was assessed using product limit method and log-rank test.

RESULTS

Seventy-nine patients were entered into the study. Thirty-seven patients were randomised to intervention debulking surgery, 25 (67%) of whom underwent intervention debulking surgery, which was performed a median of 13 weeks after primary surgery. The median survival for the intervention debulking surgery group was 15 months (95% CI 10-20 mo) and that of those randomised to chemotherapy alone, which was 12 months (95% CI 8-16 mo), were not significantly different (hazard ratio = 0.71; 95% CI 0.44-1.13).

CONCLUSION

Intervention debulking surgery may not improve survival in patients with advanced ovarian cancer.

Suppression of allogeneic reactivity in vitro by the syncytiotrophoblast membrane glycocalyx of the human term placenta is carbohydrate dependent

Immunosuppressive factors isolated from trophoblast are known to block both innate and major histocompatibility complex (MHC)-dependent cell-mediated immune responses in vitro and, in some cases, in vivo. We investigated the biochemical nature of these factors, which is presently unknown. Immunosuppressive activity, assessed by inhibition of two-way MLR, was extracted from term syncytiotrophoblast microvilli using 3 M KCl. The activity resisted both extensive pronase digestion and heating to 90 degrees C for 1 h, demonstrating that intact membrane proteins were not required. Although purified protein-linked oligosaccharides released by hydrazinolysis from the syncytiotrophoblast membrane were themselves inactive, they blocked the immunosuppressive activity of the KCl extract. After pronase digestion, the activity could be fractionated by TSK 55S gel filtration, followed by C18 reverse-phase chromatography. Sequential exoglycosidase digestion of hydrazine-released sugars of the active fraction demonstrated that it contained neutral N-linked oligomannose and hybrid oligosaccharides, which normally make up < 3% of the total syncytiotrophoblast-derived protein glycan library. These glycopeptides of the active fraction were associated with membrane phospholipid micelles. The possible mechanism by which incompletely processed N-linked oligosaccharides expressed by a variety of syncytiotrophoblast membrane glycoproteins may block allogeneic reactivity when presented as polyvalent sugar groups is discussed.

Management of severe, early pre-eclampsia: is conservative management justified?

A retrospective analysis was performed to assess the fetal and maternal benefits of allowing women presenting with severe pre-eclampsia between 24 and 32 weeks to continue their pregnancy following treatment of their hypertension. Cases presenting in Oxford (conservative management) and in Birmingham (stabilisation and early intervention) were compared. Patients were considered to require treatment when their systolic blood pressure was > or = 170 mmHg systolic or > or = 110 mmHg diastolic, associated with at least 1+ proteinuria and hyperuricaemia. We compared gestation at delivery, birth weight and neonatal complications for each group, and any maternal morbidity. There were 28 patients in each group. Gestational age at delivery was significantly less in the group managed by early intervention. Those women managed conservatively gained a mean of 9.5 days (range 2-26 days; P < 0.05), and their birthweight was significantly greater (P < 0.05). There was a significant difference between the length of stay in the neonatal intensive care unit between the 2 groups (P < 0.05), the babies of those women managed conservatively staying a mean of 7.4 days less. There were fewer neonatal complications in those cases managed conservatively, the number of newborns with 1 or more complications in the early intervention group being 18 (64.3%), compared with 8 (28.6%) in the expectant management group (P = 0.0001). All of the women in the group managed by early intervention recovered with no severe complications. However, those women managed conservatively had a higher incidence of HELLP (2 cases) and ELLP syndrome (2 cases), 1 case requiring temporary renal dialysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of the three endothelin genes and plasma levels of endothelin in pre-eclamptic and normal gestations

1. Maternal vasoconstriction and fetal growth retardation are part of the syndrome of pre-eclampsia and are thought to be related to placental insufficiency. There is evidence to suggest that the powerfully vasoactive endothelin peptides might be involved in the pathogenesis. 2. The production of endothelins appears to be regulated mainly by modulation of mRNA levels, and they are thought to exert their effects locally, rather than systemically. Hence, the measurement of endothelin mRNA levels in tissues would be expected to reflect the activity of the endothelin systems. 3. RNAase protection assays, using specific antisense probes capable of distinguishing between the endothelin mRNA isoforms, have been used to examine the expression of the three endothelin genes in placental villous tissue, amniotic membrane and myometrium. Samples were taken from 15 pre-eclamptic women and from 14 women with normal gestations. Myometrium was taken at hysterectomy from five non-pregnant women as an additional control. Plasma concentrations of immunoreactive endothelin [endothelin-1, endothelin-2 and big endothelin (not distinguished)] were measured in samples taken concurrently from uterine vein and peripheral blood during surgery in ten patients. 4. The level of endothelin-1 mRNA in placental villous tissue was significantly higher in pre-eclamptic women (32 weeks gestation) than in control subjects (38 weeks gestation) (1.85 +/- 0.26 versus 0.52 +/- 0.09 arbitrary units, means +/- SEM, P < 0.001) and in gravid than in non-gravid myometrium (P < 0.001). Endothelin-2 was not expressed in villous tissue, but was expressed in amniotic membrane and myometrium, with relatively little difference between pre-eclamptic and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of placental syncytiotrophoblast microvillous membranes from normal and pre-eclamptic women on the growth of endothelial cells in vitro

OBJECTIVES

To determine if placental syncytiotrophoblast microvillous (STBM) membranes contain factors which could cause the maternal endothelial cell disturbance thought to be central to the pathophysiology of the maternal syndrome of pre-eclampsia.

DESIGN

STMB membranes isolated from pre-eclamptic or normal placentae were added to cultures of endothelial cells and their effect on the proliferation (measured by 3H-thymidine incorporation), viability (measured by 51Cr release) and growth as a monolayer of these cells was determined. Membranes prepared from red blood cells, and non-endothelial adherent and nonadherent cell lines were used as specificity controls.

SUBJECTS

STBM membranes were isolated from the placentae of primigravid women, 10 having caesarean sections for breech presentations and 10 for pre-eclampsia.

RESULTS

STBM membranes from the placentae of normal and pre-eclamptic women suppressed endothelial cell proliferation to a similar extent and disrupted the cell monolayer to form a honeycomb-like pattern. This change in morphology was seen before significant endothelial cell death occurred. Red blood cell membranes had no effect on either endothelial cell proliferation, viability or monolayer integrity. Endothelial cells from human umbilical arteries and bovine adrenal capillaries were similarly suppressed, but comparable concentrations of STBM membranes had no effect on non-endothelial cell lines.

CONCLUSIONS

Syncytiotrophoblast microvillous membranes specifically interfered with endothelial cell growth in vitro. Our results demonstrate that there are trophoblast products which could cause the maternal syndrome of pre-eclampsia through endothelial cell damage.