Confocal laser scanning microscope study of terminal villi vessels in normal term and pre-eclamptic placentas

Human Cord Blood Endothelial Progenitor Cells and Pregnancy Complications (Preeclampsia, Gestational Diabetes Mellitus, and Fetal Growth Restriction)

Hemangioblasts give rise to endothelial progenitor cells (EPCs), which also express the cell surface markers CD133 and c-kit. They may differentiate into the outgrowth endothelial cells (OECs) that control neovascularization in the developing embryo. According to numerous studies, reduced levels of EPCs in circulation have been linked to human cardiovascular disorders. Furthermore, preeclampsia and senescence have been linked to levels of EPCs produced from cord blood. Uncertainties surround how preeclampsia affects the way EPCs function. It is reasonable to speculate that preeclampsia may have an impact on the function of fetal EPCs during the in utero period; however, the present literature suggests that maternal vasculopathies, including preeclampsia, damage fetal circulation. Additionally, the differentiation potential and general activity of EPCs may serve as an indicator of the health of the fetal vascular system as they promote neovascularization and repair during pregnancy. Thus, the purpose of this review is to compare-through the assessment of their quantity, differentiation potency, angiogenic activity, and senescence-the angiogenic function of fetal EPCs obtained from cord blood for normal and pregnancy problems (preeclampsia, gestational diabetes mellitus, and fetal growth restriction). This will shed light on the relationship between the angiogenic function of fetal EPCs and pregnancy complications, which could have an effect on the management of long-term health issues like metabolic and cardiovascular disorders in offspring with abnormal vasculature development.

Fetoplacental Disposition and Toxicity of Cadmium in Mice Lacking the Bcrp Transporter

The environmental toxicant cadmium (Cd) impairs the growth of rodents and humans in utero which in turn heightens susceptibility to diseases later in life. We previously demonstrated that the maternal-facing efflux transporter, breast cancer resistance protein (human BCRP/ABCG2, mouse Bcrp/Abcg2) confers resistance against Cd toxicity in human trophoblasts. In the current study, we sought to determine whether the absence of Bcrp alters the fetoplacental disposition and toxicity of Cd in mice. Pregnant female wild-type (WT) and Bcrp-null mice (n = 9-10/group) were administered a single injection of saline (5 ml/kg) or CdCl2 (5 mg/kg) on gestational day (GD) 9. Following Cd treatment, Bcrp-null offspring were shorter and accumulated more Cd in their placentas on GD 17 compared to WT mice. Because Cd can adversely impact placentation and transplacental nutrient delivery in mice, multiple pathways were assessed using morphometrics and immunohistochemistry including placenta zonation, vasculature development, and nutrient transporter expression. Most notably, the placentas of Bcrp-null mice had reduced immunostaining of the cell adhesion marker, β-catenin, and the trophoblast marker, cytokeratin, as well as decreased expression of divalent metal nutrient transporters (Dmt1, Zip14, and ZnT1) following Cd treatment. In summary, the absence of Bcrp expression increased placental concentrations of Cd which was associated with shorter fetal size that may be related to differential changes in molecular patterns of placental development and nutrition.

Cadmium reduces growth of male fetuses by impairing development of the placental vasculature and reducing expression of nutrient transporters

In utero exposure to the toxic metal cadmium (Cd) alters fetoplacental growth in rodents and has been inversely associated with birth weight and infant size in some birth cohorts. Moreover, studies suggest that Cd may have differential effects on growth and development according to offspring sex. The purpose of the current study was to evaluate changes in male and female fetoplacental development following a single injection of saline (5 ml/kg ip) or cadmium chloride (CdCl2, 2.5, 5 mg/kg, ip) on gestational day (GD) 9. By GD18, no changes in fetal or placental weights were observed after treatment with 2.5 mg/kg CdCl2. By comparison, the weight and length of male fetuses and their placentas were reduced following treatment with 5 mg/kg CdCl2 whereas no change was observed in females. In addition, the area of maternal and fetal blood vessels as well as the expression of the glucose transporters, Glut1 and Glut3, and the endothelial marker, CD34, were reduced in the placentas of CdCl2-treated male offspring compared to females. Interestingly, the placentas of females accumulated 80% more Cd than males after CdCl2 (5 mg/kg) administration. Female placentas also had higher concentrations of zinc and the zinc transporter Znt1 compared to males which may explain the limited changes in fetal growth observed following CdCl2 treatment. Taken together, disruption of vasculature development and reduced expression of glucose transporters in the placenta provide potential mechanisms underlying reduced fetal growth in male offspring despite the greater accumulation of Cd in female placentas.

Developments in functional imaging of the placenta

The placenta is both the literal and metaphorical black box of pregnancy. Measurement of the function of the placenta has the potential to enhance our understanding of this enigmatic organ and serve to support obstetric decision making. Advanced imaging techniques are key to support these measurements. This review summarises emerging imaging technology being used to measure the function of the placenta and new developments in the computational analysis of these data. We address three important examples where functional imaging is supporting our understanding of these conditions: fetal growth restriction, placenta accreta, and twin-twin transfusion syndrome.

Definition and Quantification of Three-Dimensional Imaging Targets to Phenotype Pre-Eclampsia Subtypes: An Exploratory Study

Pre-eclampsia is a severe placenta-related complication of pregnancy with limited early diagnostic and therapeutic options. Aetiological knowledge is controversial, and there is no universal consensus on what constitutes the early and late phenotypes of pre-eclampsia. Phenotyping of native placental three-dimensional (3D) morphology offers a novel approach to improve our understanding of the structural placental abnormalities in pre-eclampsia. Healthy and pre-eclamptic placental tissues were imaged with multiphoton microscopy (MPM). Imaging based on inherent signal (collagen, and cytoplasm) and fluorescent staining (nuclei, and blood vessels) enabled the visualization of placental villous tissue with subcellular resolution. Images were analysed with a combination of open source (FIJI, VMTK, Stardist, MATLAB, DBSCAN), and commercially (MATLAB) available software. Trophoblast organization, 3D-villous tree structure, syncytial knots, fibrosis, and 3D-vascular networks were identified as quantifiable imaging targets. Preliminary data indicate increased syncytial knot density with characteristic elongated shape, higher occurrence of paddle-like villous sprouts, abnormal villous volume-to-surface ratio, and decreased vascular density in pre-eclampsia compared to control placentas. The preliminary data presented indicate the potential of quantifying 3D microscopic images for identifying different morphological features and phenotyping pre-eclampsia in placental villous tissue.

Multiscale and multimodal imaging of utero-placental anatomy and function in pregnancy

Placental structures at the nano-, micro-, and macro scale each play important roles in contributing to its function. As such, quantifying the dynamic way in which placental structure evolves during pregnancy is critical to both clinical diagnosis of pregnancy disorders, and mechanistic understanding of their pathophysiology. Imaging the placenta, both exvivo and invivo, can provide a wealth of structural and/or functional information. This review outlines how imaging across modalities and spatial scales can ultimately come together to improve our understanding of normal and pathological pregnancies. We discuss how imaging technologies are evolving to provide new insights into placental physiology across disciplines, and how advanced computational algorithms can be used alongside state-of-the-art imaging to obtain a holistic view of placental structure and its associated functions to improve our understanding of placental function in health and disease.

Intrauterine Inflammation Damages Placental Angiogenesis via Wnt5a-Flt1 Activation

Intrauterine inflammation is the main reason for neonatal adverse outcomes and normal placenta perfusion plays an important role in fetal development. However, whether inflammation will affect placental angiogenesis and the underlying mechanism are still poorly understood. To investigate lipopolysaccharide (LPS)-induced intrauterine inflammation on placenta angiogenesis and Wnt5a-Flt1 expression. LPS-induced intrauterine inflammation rat model was established. Preterm rat outcomes were analyzed and angiogenesis of placenta villi was calculated by immunohistochemistry (IHC) of CD34 staining, and placenta Wnt5a-Flt1 expression was detected by western blot and IHC. Compared to control group, neonatal rats in LPS group showed higher death rate (1.4% vs 10.1%, p < 0.05) and lower birth weight (6.36 ± 0.48 vs 5.70 ± 0.67, p < 0.01); the villi vessel area and mean diameter in the placenta were significantly reduced in the LPS group (total area %, 16.7% ± 0.6% vs 8.7% ± 0.4%, p < 0.01, n = 9; mean diameter (pixel), 15.6 ± 0.5 vs 12.9 ± 0.3, p < 0.01, n = 9). Placenta Wnt5a-Flt1 expression was upregulated significantly (integrated optical density (IOD) in IHC: Wnt5a, 1667 ± 1204 vs 11,076 ± 4046, p < 0.05; Flt1, 2554 ± 466.2 vs 7998 ± 1613, p < 0.05; western blot: Wnt5a, 0.33 ± 0.05 vs 0.96 ± 0.06, p < 0.05; Flt1, 0.36 ± 0.15 vs 1.08 ± 0.08, p < 0.05). Intrauterine inflammation gave rise to offspring death rate and low birth weight; the mechanism might be disordered placental angiogenesis via Wnt5a-Flt1 activation triggered by inflammation.

Quantitative characterization of rodent feto-placental vasculature morphology in micro-computed tomography images

BACKGROUND AND OBJECTIVE

Optimal development of placental vasculature is critical for fetal growth and health outcomes. Many studies characterizing the vascular structure of the fetal side of the placenta have utilized a range of two-dimensional and three-dimensional (3D) imaging techniques including X-ray micro-computed tomography (micro-CT) following perfusion of the vasculature with a radio-opaque compound. The CT approach has been used to study feto-placental vasculature in rodents and humans. Its inherent advantage is that it reveals the 3D structure in high resolution without destroying the sample. This permits both multiple scanning of the sample and follow-up histological investigations in the same sample. Nevertheless, the applicability of the approach is hampered both by the challenging segmentation of the vasculature and a lack of straightforward methodology to quantitate the feto-placental vascular network. This paper addresses these challenges.

METHODS

An end-to-end methodology is presented for automatically segmenting the vasculature; obtaining a Strahler-ordered rooted-tree representation and extracting quantitative features from its nodes, segments and branches (including volume, length, tortuosity and branching angles). The methodology is demonstrated for rat and mouse placentas at the end of gestation (day 22 and day 18, respectively), perfused with Microfil® and imaged using two different micro-CT scanners.

RESULTS

The 3D visualizations of the resulting vascular trees clearly demonstrate differences between the branching complexity, tree span and tree depth of the mouse and rat placentas. The quantitative characterizations of these trees include not only the fundamental features that have been utilized in other studies of feto-placental vasculature but also several additional features. Boxplots of several of these-tortuosity, number of side branches, number of offspring per branch and branch volume-computed at each Strahler order are presented and interpreted. Differences and similarities between the mouse and rat casts are readily detected.

CONCLUSION

The proposed end-to-end methodology, and the implementation presented using a combination of Amira and Matlab, offers researchers in the field of placental vasculature characterization a straightforward and objective approach for quantifying micro-CT vascular datasets.

Three-dimensional morphological analysis of placental terminal villi

Transport of nutrients and waste between the maternal and fetal circulations during pregnancy takes place at the final branches of the placental villous trees. Therefore, and unsurprisingly, pregnancy complications have been related to the maldevelopment of terminal villi. However, a deep analysis of placental villous morphology has been limited by tissue processing and imaging techniques. In this proof-of-principle study, placental lobules were fixed by perfusion and small clumps of villi were stained, sectioned optically and reconstructed. Morphological and network analyses were suggested and demonstrated on samples of normal placentas. The results show that most parameters are almost constant within a placenta but that there exists an inter-individual variation. Network analysis suggests that the feto-placental capillary network has several paths within an individual villus, serving as an efficient transport system. Three-dimensional reconstruction from confocal laser scanning microscopy images is a potent technique able to quantify placental architecture and capture the significant irregularities in vessel diameter and membrane thickness. This approach has the potential to become a powerful tool to further our understanding of the differences in placental structure which may underlie pregnancy complications.

Pericytes in the Placenta: Role in Placental Development and Homeostasis

The placenta is the most variable organ, in terms of structure, among the species. Besides it, all placental types have the same function: production of viable offspring, independent of pregnancy length, litter number, or invasion level. The angiogenesis is a central mechanism for placental functionality, due to proper maternal-fetal communication and exchanges. Much is known about the vasculature structure, but little is known about vasculature development and cellular interactions. Pericytes are perivascular cells that were described to control vasculature stability and permeability. Nowadays there are several new functions discovered, such as lymphocyte modulation and activation, macrophage-like phagocytic properties, tissue regenerative and repair processes, and also the ability to modulate stem cells, majorly the hematopoietic. In parallel, placental tissues are known to be a particularly immune microenvironment and a rich stem cell niche. The pericyte function plethora could be similar in the placental microenvironment and could have a central role in placental development and homeostasis.

Semaphorin 3F expression is reduced in pregnancy complicated by preeclampsia. An observational clinical study

Background and objective

Preeclampsia is a systemic disorder, affecting 2–10% of pregnancies, characterized by a deregulated pro- and anti-angiogenic balance. Semaphorin 3F is an angiogenesis inhibitor. We aimed to investigate whether semaphorin 3F expression is modulated in preeclampsia.

Design, setting, participants, and measurements

We performed two observational single center cohort studies between March 2013 and August 2014. In the first we enrolled 110 consecutive women, undergoing an elective cesarean section; in the second we included 150 consecutive women undergoing amniocentesis for routine clinical indications at 16–18 week of gestation. Semaphorin 3F concentration was evaluated in maternal peripheral blood, venous umbilical blood and amniotic fluid, along with its placenta protein expression at the time of delivery in the first study group and in the amniotic fluid at 16–18 weeks of gestation in the second study group.

Results

In the first study 19 patients presented at delivery with preeclampsia. Semaphorin 3F placenta tissue expression was significantly reduced in preeclampsia. In addition, semaphorin 3F level at delivery was significantly lower in serum, amniotic fluid and venous umbilical blood of preeclamptic patients compared with normal pregnant women. In the prospective cohort study 14 women developed preeclampsia. In this setting, semaphorin 3F amniotic level at 16–18 weeks of gestation was reduced in women who subsequently developed preeclampsia compared to women with a normal pregnancy. ROC curve analysis showed that semaphorin 3F amniotic levels could identify women at higher risk of preeclampsia.

Conclusions

Semaphorin 3F might represent a predictive biomarker of preeclampsia.

Effect of THP-1 Cells on the Formation of Vascular Tubes by Endothelial EA.hy926 Cells in the Presence of Placenta Secretory Products

We studied the effect of THP-1 cells on the formation of vessel-like structures by endothelial cells in the presence of placenta-conditioned media. Addition of THP-1 cells to endothelial cells cultured in the presence of media conditioned by first-trimester placentas led to an increase in the length of cell tubes and reduced their number in comparison with endothelial cell monoculture. In the presence of media conditioned by third-trimester placentas, THP-1 cells did not affect the length and number of cell tubes formed by endothelial cells. When evaluating the formation of vessel-like structures by endothelial cells in co-culture, marked decrease in the length of cell tubes in the presence of media conditioned by first-trimester placentas vs. third-trimester placentas was noted. No differences in the length and number of cell tubes formed by endothelial cells co-cultured with THP-1 cells in the presence of placental factors from women with preeclampsia and uncomplicated pregnancy were found. These findings can reflect the peculiarities of the influence of macrophages on the formation of blood vessels by endothelial cells in the placenta.

Adenosine A2A receptor regulates expression of vascular endothelial growth factor in feto-placental endothelium from normal and late-onset pre-eclamptic pregnancies

We aim to investigate whether A_2A/nitric oxide-mediated regulation of vascular endothelial growth factor (VEGF) expression is impaired in feto-placental endothelial cells from late-onset pre-eclampsia. Cultures of human umbilical vein endothelial cells (HUVECs) and human placental microvascular endothelial cells (hPMECs) from normal and pre-eclamptic pregnancies were used. Assays by using small interference RNA (siRNA) for A_2A were performed, and transfected cells were used for estimation of messenger RNA (mRNA) levels of VEGF, as well as for cell proliferation and angiogenesis in vitro. CGS-21680 (A_2A agonist, 24 h) increases HUVEC and hPMEC proliferation in a dose response manner. Furthermore, similar to CGS-21680, the nitric oxide donor, S-nitroso-N-acetyl-penicillamine oxide (SNAP), increased cell proliferation in a dose response manner (logEC₅₀ 10^-9.2 M). In hPMEC, CGS-21680 increased VEGF protein levels in both normal (∼1.5-fold) and pre-eclamptic pregnancies (∼1.2-fold), an effect blocked by the A_2A antagonist, ZM-241385 (10^-5 M) and the inhibitor of NO synthase, N _ω-nitro-L-arginine methyl ester hydrochloride (L-NAME). Subsequently, SNAP partially recovered cell proliferation and in vitro angiogenesis capacity of cells from normal pregnancies exposed to siRNA for A_2A. CGS-21680 also increased (∼1.5-fold) the level of VEGF mRNA in HUVEC from normal pregnancies, but not in pre-eclampsia. Additionally, transfection with siRNA for A_2A decrease (∼30 %) the level of mRNA for VEGF in normal pregnancy compared to untransfected cells, an effect partially reversed by co-incubation with SNAP. The A_2A-NO-VEGF pathway is present in endothelium from microcirculation and macrocirculation in both normal and pre-eclamptic pregnancies. However, NO signaling pathway seems to be impaired in HUVEC from pre-eclampsia.

Three-dimensional modeling of human placental terminal villi

INTRODUCTION

Placental transport is the main factor affecting the health and development of the fetus. Due to the placenta's geometrical and mathematical complexity, the structure-function relations of placental terminal villi have not been successfully modeled. Hence, a novel modeling approach is proposed.

METHODS

Computational models of four different specimens were generated from the three-dimensional reconstruction of confocal laser scanning microscopic image stacks. To evaluate the capabilities of the proposed methodology, stationary oxygen diffusion transport was calculated in the terminal villus volumes.

RESULTS

The reconstructions automatically provided the spatial arrangement of the fetal capillaries inside the terminal villi. The surface and volume ratios between the fetal capillaries and the villus were also calculated, and the effects of model parameters on the placental diffusive capacity were assessed by parametric analysis.

DISCUSSION

The potential of three-dimensional reconstructions combined with finite element analysis as a research tool for the human placenta was tested. The methodology herein could serve in the future as a simulation platform for complicated in vivo and in vitro scenarios.

The role of morphology in mathematical models of placental gas exchange

The performance of the placenta as a gas exchanger has a direct impact on the future health of the newborn. To provide accurate estimates of respiratory gas exchange rates, placenta models need to account for both the physiology of exchange and the organ morphology. While the former has been extensively studied, accounting for the latter is still a challenge. The geometrical complexity of placental structure requires use of carefully crafted approximations. We present here the state of the art of respiratory gas exchange placenta modeling and demonstrate the influence of the morphology description on model predictions. Advantages and shortcomings of various classes of models are discussed, and experimental techniques that may be used for model validation are summarized. Several directions for future development are suggested.

Morphometric evaluation of preeclamptic placenta using light microscopic images

Deficient trophoblast invasion and anomalies in placental development generally lead to preeclampsia (PE) but the inter-relationship between placental function and morphology in PE still remains unknown. The aim of this study was to evaluate the morphometric features of placental villi and capillaries in preeclamptic and normal placentae. The study included light microscopic images of placental tissue sections of 40 preeclamptic and 35 normotensive pregnant women. Preprocessing and segmentation of these images were performed to characterize the villi and capillaries. Fisher's linear discriminant analysis (FLDA), hierarchical cluster analysis (HCA), and principal component analysis (PCA) were applied to identify the most significant placental (morphometric) features from microscopic images. A total of 10 morphometric features were extracted, of which the villous parameters were significantly altered in PE. FLDA identified 5 highly significant morphometric features (>90% overall discrimination accuracy). Two large subclusters were clearly visible in HCA based dendrogram. PCA returned three most significant principal components cumulatively explaining 98.4% of the total variance based on these 5 significant features. Hence, quantitative microscopic evaluation revealed that placental morphometry plays an important role in characterizing PE, where the villous is the major component that is affected.

The effect of smoking on early chorionic villous vascularisation

The aim of the study was to investigate whether first trimester chorionic villous vascularisation is different in women who smoked cigarettes before and during pregnancy in comparison with women who did not smoke. Placentas of smoking (>10 cigarettes/day, n = 13) and non-smoking women (n = 13), scheduled for a legal termination of a viable first trimester pregnancy for social indications, were retrieved. Placental tissues of 3-5 mm³ were whole mount CD31 immunofluorescence stained. Images of the CD31 immunofluorescence and contour of the villi were captured using an Optical Projection Tomography scanner. An immersive BARCO virtual reality system was used to create an enlarged interactive 3-dimensional hologram of the reconstructed images. Automatic volume measurements were performed using a flexible and robust segmentation algorithm that is based on a region-growing approach in combination with a neighbourhood variation threshold. The villous volume, vascular volume and vascular density were measured for the total chorionic villous tree as well as for its central and peripheral parts. No differences in maternal age and gestational age were found between non-smoking and smoking women. No differences were found in the total, central and peripheral villous tree volume and vascular volume. The central (13.4% vs. 9.5%, p=0.03) and peripheral (8.4% vs. 6.4%, p=0.02) villous tree vascular densities were increased in the smoking women as compared with the non-smoking women. In conclusion, chorionic villous vascularisation is already altered in first trimester of pregnancy in women who smoked cigarettes before and during pregnancy.

The clinical significance of large placental lakes

OBJECTIVE

The aim of our study was to establish whether there is a correlation between the size of placental lakes and adverse pregnancy outcome.

STUDY DESIGN

Target ultrasonography for diagnosis of placental lake was performed in the 2nd trimester of pregnancy and followed up in the 3rd trimester. Placental lakes were defined as homogenous sonolucent avillous lesions greater than 2 cm × 2 cm in diameter. The 109 pregnant women enrolled in this study were divided into four groups according to the size and change in size of placental lakes. Clinical characteristics and pregnancy outcomes in each group were compared.

RESULTS

Some placental lakes decreased and disappeared, whereas others persisted. There were no significant differences in clinical characteristics among the four investigated groups. Fetal small-for-gestational-age status was significantly correlated with large placental lakes, compared to small.

CONCLUSION

Large placental lakes were correlated with the fetal status of small for gestational age. Therefore, if a large placental lake is identified in the 2nd trimester of pregnancy, appropriate surveillance should be considered for the remainder of the pregnancy.

Pilot study of comparative placental morphometry in pre-eclamptic and normotensive pregnancies suggests possible maladaptations of the fetal component of the placenta

OBJECTIVE

Adequate maternal, intervillous and fetal blood flow are all necessary for fetal well-being. Compromise to any part of this exchange would be detrimental to pregnancy outcome. Pre-eclampsia is associated with reduced maternal spiral artery flow, resulting in reduced placental perfusion. This in turn creates an ischaemic environment, which may predispose to morphological changes in placental villi. This pilot study sought to assess whether there were morphological alterations in the fetal component of the placenta which could be detrimental to exchange and therefore pregnancy outcome.

STUDY DESIGN

This study utilized morphometric image analysis to examine some features of the fetal component of the placenta in normotensive (NT) and pre-eclamptic (PE) groups. The features examined included: density of placental villi (expressed as percentage of field area occupied by placental tissue); stem vessel carrying capacity (expressed as percentage of stem villus area occupied by vessel lumina); the thickness of the stem arterial walls relative to artery size (expressed as percentage of artery area occupied by arterial wall) and the extent of fibrosis associated with villi (expressed as percentage of field area occupied by fibrosis).

RESULTS

There were significant differences between NT and PE placentae in density of placental villus arrangement NT: 51.89 ± 6.19, PE: 64.78 ± 6.93 (P<0.001); carrying capacity of stem villi NT: 17.20 ± 11.78, PE: 8.67 ± 8.51 (P<0.001); relative thickness of stem villi arterial walls NT: 74.08 ± 12.92, PE: 86.85 ± 10.55 (P<0.001); and extent of fibrosis NT: 0.727 ± 0.310, PE: 1.582 ± 0.707 (P<0.001).

CONCLUSION

These significant differences between normotensive and pre-eclamptic placentae suggest possible fetal maladaptations in response to the intervillous ischaemia, compounding the existing maternal compromise to materno-fetal exchange. Further investigations would, however, be necessary in order to make more conclusive deductions.

Increased senescence and reduced functional ability of fetal endothelial progenitor cells in pregnancies complicated by preeclampsia without intrauterine growth restriction

OBJECTIVE

The aim of this study was to investigate the number and functional ability of fetal endothelial progenitor cells in pregnancies complicated by preeclampsia without intrauterine growth restriction.

STUDY DESIGN

Fetal endothelial progenitor cells were isolated, and counted from 17 women with preeclampsia without intrauterine growth restricion and 30 normal women. Colony-forming assay and differentiation time assay were performed to detect functional activity of the cells. To assess cellular senescence, senescence-associated beta-galactosidase staining was performed for endothelial progenitor cells.

RESULTS

Compared with normal pregnancy, the number of endothelial progenitor cells was significantly lower, differentiation time from endothelial progenitor cell into outgrowing cell was longer, and the number of colonies after differentiation was smaller in preeclampsia (P< .001), respectively. The intensity of senescence-associated beta-galactosidase staining was higher in preeclamptic pregnancy (P < .001).

CONCLUSION

The number and functional ability of fetal endothelial progenitor cells from preeclampsia without intrauterine growth restriction are significantly decreased and they are more senescent compared with those of normal pregnancy.

Application of cryo-compatible antibodies to human placenta paraffin sections

The hepes-glutamic acid buffer-mediated organic solvent protection effect (HOPE) -fixation and paraffin embedding technique has been described to expand possibilities for immuno-labellings due to low denaturation of proteins. In this study, the issue was addressed as to whether the HOPE technique could be a useful tool in placenta tissue-based studies when only cryo-compatible antibodies are available. Such antibodies can be used on cryostat sections only, giving results of considerably inferior morphological detail as compared to routinely fixed paraffin embedded tissue sections. Commercially available, only cryo-compatible, monoclonal antibodies against a conformational epitope of HLA-G (clone MEM-G/9) and leukocyte differentiation antigens CD56, CD163 and CD34 III were selected and applied to frozen sections, routinely formalin-fixed and HOPE-fixed paraffin sections. All tested antibodies immunolocalized their antigen on cryo sections and on HOPE-fixed but not formalin-fixed paraffin sections. The HOPE technique provides an excellent preservation of protein antigenicity together with well presented morphological details in paraffin embedded placenta tissues. The detection of native or conformation-dependent epitopes in paraffin sections expands the immunolocalization possibilities in placenta research and reproductive immunology.

The architecture of first trimester chorionic villous vascularization: a confocal laser scanning microscopical study

BACKGROUND

The aim of this study was to investigate normal chorionic villous vascularization using CD31 immunofluorescence and confocal laser scanning microscopy (CLSM) to elucidate the spatial arrangement in terms of connections between vessels and cords and their branching patterns compared to deficient chorionic villous vascularization in complicated pregnancies.

METHODS

A descriptive morphologic study using CLSM after CD31 immunofluorescence staining of placental biopsies from normal pregnancies (n = 20), complete hydatidiform molar pregnancies (CHMs; n = 3) and empty sacs (n = 3), with a well documented gestational age (GA).

RESULTS

In this three-dimensional study, first trimester chorionic villi were occupied by a complex network of mainly cords with redundant connections as early as 5(+5) weeks GA. With increasing GA cords transform into vessels. From about 9 weeks GA onwards, vascular development is characterized by the presence of two large vessels located centrally and surrounded by and connected to a capillary network. In first trimester CHM and empty sacs, we observed a primitive network of mainly cords.

CONCLUSIONS

This first visualization of the spatio-temporal patterns of blood vessel formation in placental villi is characterized by the development of the vasculosyncytial membrane from a complex network of cords and can be regarded as the placental development before it becomes functional at the end of organogenesis.