Human IgG Fc-engineering for enhanced plasma half-life, mucosal distribution and killing of cancer cells and bacteria.

Monoclonal IgG antibodies constitute the fastest growing class of therapeutics. Thus, there is an intense interest to design more potent antibody formats, where long plasma half-life is a commercially competitive differentiator affecting dosing, frequency of administration and thereby potentially patient compliance. Here, we report on an Fc-engineered variant with three amino acid substitutions Q311R/M428E/N434W (REW), that enhances plasma half-life and mucosal distribution, as well as allows for needle-free delivery across respiratory epithelial barriers in human FcRn transgenic mice. In addition, the Fc-engineered variant improves on-target complement-mediated killing of cancer cells as well as both gram-positive and gram-negative bacteria. Hence, this versatile Fc technology should be broadly applicable in antibody design aiming for long-acting prophylactic or therapeutic interventions.

Contribution of the ex vivo placental perfusion model in understanding transplacental immunoglobulin G transfer.

INTRODUCTION: The acquisition of humoral immunity in utero is essential for the fetus. The crucial protein, which is responsible for this part of immunity, is immunoglobulin-G (IgG). Immune functions of IgGs are mediated via the interaction of the crystallizable fragment (Fc) region of IgG with specific Fc γ receptors (FcγRs). However, an atypical FcγR, the neonatal Fc receptor (FcRn), is a key regulator of IgG transfer across the human placenta. During the last four decades ex vivo placental perfusion studies have contributed significantly to the study of mechanisms of IgG transfer across the multicellular placental barrier. METHOD: A PubMed search was conducted by using specific keywords: placenta, perfusion and IgG to review manuscripts using human placental perfusion to study the transplacental transfer of IgG. Relevant studies found in reference lists of these manuscripts were also added to the review, and references were included that supported or gave nuance to the discussion of the mechanisms of IgG kinetics in the placenta. RESULTS AND DISCUSSION: We found twenty publications on the study of transplacental transfer of IgG using human ex vivo placental perfusion, by research groups with partly different settings. This review summarizes knowledge about placental IgG transfer, with a strong focus on the contributions from ex vivo placental perfusion studies.

Ex vivo dual perfusion of an isolated human placenta cotyledon: Towards protocol standardization and improved inter-centre comparability.

Since the full development of the ex vivo dual perfusion model of the human placenta cotyledon, the technique has provided essential insight into how nutrients, lipids, gases, immunoglobulins, endocrine agents, pharmaceuticals, chemicals, nanoparticles, micro-organisms and parasites might traverse the maternofetal barrier. Additionally, the model has been instrumental in gaining a better understanding of the regulation of vascular tone, endocrinology and metabolism within this organ. The human placenta is unique amongst species in its anatomy and transfer modalities. This orthologous diversity therefore requires an appropriate consideration of placental transfer rates of compounds, particles and micro-organisms specific to humans. Different research centres have adapted this model with a wide variation in perfusion parameters, including in the establishment of perfusion, perfusate composition, gassing regime, cannulation method, flow rates, perfused tissue mass, and also in the application of quality control measures. The requirement to harmonise and standardise perfusion practice between centres is largely driven by the need to obtain consistency in our understanding of placental function, but also in the qualification of the model for acceptance by regulatory agencies in drug and toxicology testing. A pilot study is proposed, aiming to describe how existing inter-centre variation in perfusion methodology affects placental metabolism, protein synthesis, oxygen consumption, the materno-fetal transfer of key molecular markers, and placental structure.

Placental transport of parabens studied using an ex-vivo human perfusion model.

INTRODUCTION: Parabens are a group of chemicals widely used as preservatives in daily consumer products such as cosmetics, food items, pharmaceuticals and household commodities. They have been broadly detected in human samples indicating a general human exposure, and concerns arose from their potential endocrine disrupting effect. Especially the exposure to parabens during pregnancy is concerning, as the time of fetal development is a particularly vulnerable period. The aim of this study was to investigate the transport and metabolism of four commonly used parabens: methyl-, ethyl-, propyl- and butylparaben (MeP, EtP, PrP and BuP) and the metabolite para-hydroxybenzoic acid (PHBA) across the human placenta. METHODS: An ex-vivo human placental perfusion model was used. The test compounds were added in the maternal compartment (with initial concentrations of 1 mM or 0.1 mM). Placental transport was evaluated by fetal-maternal concentration ratios (FM-ratio), transport index (TI) and indicative permeability (IP). RESULTS: Information about parabens kinetics was taken from 10 perfusions and PHBA from 7 perfusions. Paraben metabolism was not detected. The placental transport of MeP, EtP, PrP, BuP and PHBA revealed a transfer from maternal to fetal circulations with FM120 of 0.86 ± 0.27 (MeP), 0.98 ± 0.28 (EtP), 1.00 ± 0.28 (PrP), 1.12 ± 0.59 (BuP) and 0.82 ± 0.37 (PHBA). The test substances accumulated in the perfused tissue in some degree. The average kinetic parameters FM-ratio, TI and IP were not different between chemicals. DISCUSSION: The present study shows that the placenta barrier is permeable to all four parabens and the metabolite, which implies potential fetal exposure.

Intrapartum transfer of oxytocin across the human placenta: An ex vivo perfusion experiment.

INTRODUCTION: Investigation of the maternal to fetal transfer of oxytocin across the dually perfused term human placenta. METHODS: Human placentae obtained from term singleton pregnancies were utilized in a dual recirculating model of ex vivo placental perfusion. Six placentae from women delivering by elective cesarean at term were perfused, one blank and five with the test substance synthetic oxytocin (0.8 ng/mL) (OX) added to the maternal perfusate for 180 min. Antipyrine was used as positive control to validate overlap of the maternal and fetal circuits. The concentration of OX was determined by radioimmunoassay. RESULTS: A fall in maternal concentration of OX was seen throughout the experiment. At 90 min of perfusion a state of equilibrium was reached between maternal and fetal concentrations; however after 180 min the fetal concentration of OX was higher than that of the maternal. 31 % of the test substance was accounted for at the end of the experiment - suggesting OX protein binding and a high degree of oxytocinase activity. DISCUSSION: The ex vivo perfusion experiments revealed low transfer of OX to the fetal circuit below physiologically relevant concentrations.

Therapeutic concentration of ciprofloxacin and transfer across the human term placenta.

BACKGROUND: Pregnant women have an increased risk of infections, and early and decisive treatment is preferred to prevent complications. Although ciprofloxacin is very commonly used, safety aspects of maternal treatment during pregnancy are limited, and avoidance of its use during late pregnancy is recommended. OBJECTIVE: The aim is to estimate maternal-to-fetal transfer clearance of ciprofloxacin at a therapeutic concentration and to determine fetal exposure to maternally administered ciprofloxacin. STUDY DESIGN: Transplacental pharmacokinetics were determined with an ex vivo placental model, which is a reliable experimental model for estimating fetal drug exposure. Human placentas from uncomplicated term pregnancies were collected after delivery and a suitable cotyledon was cannulated. Ciprofloxacin was added at a therapeutic concentration (1.6 µg/mL) to the maternal compartment, and antipyrine was included as a reference drug (10.0 µg/mL). Samples were collected from the maternal and fetal compartment at 12 time points (-2 to 180 minutes), and the integrity and metabolic parameters were measured consecutively. Drug concentrations were determined using ultra-performance liquid chromatography-tandem mass spectrometry. RESULTS: A total of 5 human placentas from healthy term pregnancies were collected after delivery and cannulated with success. Ciprofloxacin crossed the placenta; its mean concentration in the fetal compartment was 0.3 µg/mL, accounting for 22% (0.29/1.30; range, 15%-31%) of the maternal concentration after 3 hours. The fetal/maternal ciprofloxacin concentration ratio increased gradually over time and reached 0.53. The transfer clearance for ciprofloxacin was 0.28 mL/min (range, 0.21-0.41 mL/min) during the first hour and 0.21 mL/min (range, 0.14-0.26 mL/min) during the following 2 hours. After end perfusion, the mean tissue concentration and proportion of ciprofloxacin were 0.7 µg/g and 11% (14/130; range, 7%-14%), respectively. CONCLUSION: Ciprofloxacin crossed the placenta at a slow, constant rate, indicating moderate fetal exposure. This study verifies an accumulation of ciprofloxacin in the placenta that may lengthen the duration of fetal exposure. These results are an essential element of fetal risk assessment, but further studies are needed to estimate fetal safety.

Fetal exposure to environmental chemicals; insights from placental perfusion studies.

INTRODUCTION: The burden of environmental chemicals in the human population is ubiquitous and especially problematic in pregnancy due to potential exposure of the vulnerable fetus. According to the Developmental Origins of Health and Disease hypothesis, the fetal period is highly sensitive to exposure to environmental factors that will determine the development of diseases later in life. A range of environmental chemicals has been studied in the ex vivo placental perfusion model, which is a human model using the intact placenta directly after birth to study the placental transfer and metabolism of selected compounds. METHODS: Here, we reviewed the existing knowledge on human placental perfusion of environmental chemicals in order to identify potential correlations between placental transfer and properties of chemicals and areas of future research needs. RESULTS: We found 32 studies of the following groups of environmental chemicals: pesticides, persistent organic pollutants (POPs), plastics and byproducts, phyto/myco-estrogens and fungal toxins, byproducts from heating/curing food, combustion in traffic and industry, and metals. The studies showed highly distinct transfer rates from very fast transport to the fetal side to negligible transfer. DISCUSSION: In general, a low molecular weight favors placental translocation, but placental translocation is dependent on other physicochemical properties of the substances, claiming the need for more standardized studies and proper quantitative structure-activity relationship (QSAR) analysis. Overall, we recommend using placental perfusion studies in the risk assessment of environmental toxicants, to determine the transfer, metabolism and toxic effects of this diverse class of substances, on the human term placenta.

Telomere length in newborns is associated with exposure to low levels of air pollution during pregnancy.

Telomere length (TL) is a biomarker of biological aging that may be affected by prenatal exposure to air pollution. The aim of this study was to assess the association between prenatal exposure to air pollution and TL in maternal blood cells (leukocytes), placenta and umbilical cord blood cells, sampled immediately after birth in 296 Danish mother-child pairs from a birth cohort. Exposure data was obtained using the high-resolution and spatial-temporal air pollution modeling system DEHM-UBM-AirGIS for PM2.5, PM10, SO2, NH4+, black carbon (BC), organic carbon (OC), CO, O3, NO2, and NOx at residential and occupational addresses of the participating women for the full duration of the pregnancy. The association between prenatal exposure to air pollutants and TL was investigated using distributed lag models. There were significant and positive associations between TL in umbilical cord blood cells and prenatal exposure to BC, OC, NO2, NOx, CO, and O3 during the second trimester. TL in umbilical cord blood was significantly and inversely associated with prenatal exposure to PM2.5, BC, OC, SO2, NH4+, CO and NO2 during the third trimester. There were similar inverse associations between TL from umbilical cord blood cells and air pollution exposure at the residential and occupational addresses. There were weaker or no associations between air pollution exposure and TL in placenta tissue and maternal blood cells. In conclusion, both the second and third trimesters of pregnancy are shown to be sensitive windows of exposure to air pollution affecting fetal TL.

Maternal stress and placental function; ex vivo placental perfusion studying cortisol, cortisone, tryptophan and serotonin.

BACKGROUND: Exposure to maternal stress during pregnancy can have adverse effects on the fetus, which has potential long-term effects on offspring´s development and health. We investigated the kinetics and metabolism of the hormones and amino acids: cortisol, cortisone, tryptophan and serotonin in the term placenta in an ex vivo human placental perfusion model. The placentas used in the experiments were donated from families participating in the Maternal Stress and Placental Function project with a known maternal stress background. METHOD: Cortisol, cortisone, tryptophan and serotonin were added simultaneously to the maternal side in the 6 hour ex vivo term human recirculating placental perfusion model, in four experimental set-ups: without inhibitors, with carbenoxolone -that inhibits cortisol metabolism into cortisone, with fluoxetine that inhibits the serotonin transporter, and with PCPA that inhibits metabolism of tryptophan into serotonin. The concentration of cortisol and cortisone, and tryptophan and serotonin were quantified using UPLC and HPLC-MS respectively. RESULTS: Cortisol was rapidly metabolized into cortisone in the placenta, to a somewhat lesser degree when adding the inhibitor carbenoxolone, resulting in higher fetal exposure to cortisol. Serotonin was also rapidly metabolized in the placenta. When adding fluoxetine a peak of fetal serotonin levels was seen in the first hour of the perfusion. No effect was seen of the maternal stress levels on placental transport kinetics in this study. CONCLUSION: Inhibiting the metabolism of cortisol in the placenta increased fetal exposure to cortisol as expected. Unexpectedly we saw an increased fetal exposure to serotonin when inhibiting the serotonin transporter, which may be related to the increased serotonin concentration on the maternal side of the placenta. No effect on placental kinetics were evident on maternal stress levels during the pregnancy as the majority of participating mothers had normal stress levels.

Placental transfer of pesticides studied in human placental perfusion.

To investigate the transplacental transport of pesticides, the pyrethroid cypermethrin and the fungicide azoles, propiconazole and bitertanol were tested in the placental perfusion model. Cypermethrin, propiconazole and bitertanol were also tested in the BeWo cell transfer model. The pesticides were chosen with the selection criteria: use in Denmark, significant treated areas and knowledge on hormone-disrupting effects. Propiconazole and bitertanol showed rapid transfer and adsorbance to the system in both placental perfusion and BeWo cell system, whereas cypermethrin had a slower transport across the placental cell layers in the two models. There was no difference between data of the single pesticides and their mixture in either placental perfusion or BeWo cell transfer model. Both the placental perfusion model and the BeWo cell model metabolized the pesticides and released metabolites into both foetal and maternal circulation. Using human exposure models, this study shows the potential exposure of the human foetus to pesticides cypermethrin, propiconazole and bitertanol and their metabolites.

Maternal stress and placental function, a study using questionnaires and biomarkers at birth.

BACKGROUND: Prenatal stress affects the health of the pregnant woman and the fetus. Cortisol blood levels are elevated in pregnancy, and fetal exposure to cortisol is regulated by the placenta enzyme 11ß-HSD2. A decrease in enzyme activity allows more maternal cortisol to pass through the placental barrier. Combining the fetal and maternal cortisol to cortisone ratio into the adjusted fetal cortisol exposure (AFCE) represents the activity of the enzyme 11ß-HSD2 in the placenta. AIM: To investigate the effect of prenatal maternal stress on the ratio of cortisol and cortisone in maternal and fetal blood at birth in a normal population. METHOD: Maternal self-reported stress was assessed at one time-point, as late in the pregnancy as convenient for the participant, using the Depression Anxiety Stress Scales (DASS-42), Pregnancy Related Anxiety (PRA), and Major Life Events during pregnancy. The study included 273 participants from Copenhagen University Hospital. Maternal and umbilical cord blood was sampled directly after birth and cortisol and cortisone concentrations were quantified using UPLC chromatography. Data were analyzed in a five-step regression model with addition of possible confounders. The primary outcome was AFCE, and plasma concentrations of maternal and fetal cortisol and cortisone were secondary outcomes. RESULTS: Significant associations were seen for the primary outcome AFCE and the plasma concentrations of maternal cortisol and fetal cortisone with exposure to Pregnancy Related Anxiety (PRA), though the associations were reduced when adjusting for birth related variables, especially delivery mode. The weight of the placenta affected the associations of exposures on AFCE, but not plasma concentrations of cortisol and cortisone in mother and fetus. Moreover, the study demonstrated the importance of delivery mode and birth strain on cortisol levels right after delivery. CONCLUSION: Our main finding was associations between PRA and AFCE, which shows the effect of maternal stress on placental cortisol metabolism.

Biomonitoring of Danish school children and mothers including biomarkers of PBDE and glyphosate.

BACKGROUND: The Danish part of the large European Human biomonitoring pilot project Demonstration of a study to Coordinate and Perform Human biomonitoring on a European Scale (DEMOCOPHES) investigated the urine, hair and blood concentrations of 66 different environmental chemicals in a group of 145 Danish school children aged 6-11 years and their mothers from rural and urban areas in autumn 2011. Some - but not all - results were published; however, the concurrence of the chemicals has not been assessed. METHODS: The measured concentrations of polybrominated diphenyl ethers (PBDEs) and glyphosate is assessed to complete the investigation of all 66 chemicals in DEMOCOPHES. The concentrations of PBDEs were measured in plasma samples of 143 mothers and 116 children. Glyphosate was measured in a subsample of 27 urine samples. Previously assessed chemicals were polychlorinated biphenyls (PCBs), and polyfluoroalkyl substances (PFASs) analyzed in blood samples, mercury analyzed in hair, and phthalate metabolites, parabens, phenols, cadmium, paracetamol and cotinine analyzed in urine samples. Differences in concentrations between mothers and children were assessed, and the associations between the concentrations of the different environmental chemicals. investigated by correlation analysis. RESULTS: PBDE47 was found in relatively high levels compared with previous Danish results in both mothers and children, with a significantly higher level in the children compared to their mothers. Glyphosate in concentrations around 1 ng/mL was detected in all 27 samples. The analyzed environmental exposures seem to follow a pattern where chemicals within the same classes are strongly correlated and where children and mothers are exposed to the same chemicals. CONCLUSION: The correlations between the measured environmental chemicals indicate that a specific exposure pattern may exist, where people who are highly exposed to one class of environmental chemicals also may be highly exposed to certain other classes. As some of the compounds were measured in higher levels in children compared to mothers, increased focus also on the exposure in young children is recommended. For more detailed investigation of specific exposure sources more studies with increased power and detailed questionnaires should be developed.

Comparison of functional assays used in the clinical development of a placental malaria vaccine.

BACKGROUND: Malaria in pregnancy is associated with significant morbidity in pregnant women and their offspring. Plasmodium falciparum infected erythrocytes (IE) express VAR2CSA that mediates binding to chondroitin sulphate A (CSA) in the placenta. Two VAR2CSA-based vaccines for placental malaria are in clinical development. The purpose of this study was to evaluate the robustness and comparability of binding inhibition assays used in the clinical development of placental malaria vaccines. METHODS: The ability of sera from animals immunised with different VAR2CSA constructs to inhibit IE binding to CSA was investigated in three in vitro assays using 96-well plates, petri dishes, capillary flow and an ex vivo placental perfusion assay. RESULTS: The inter-assay variation was not uniform between assays and ranged from above ten-fold in the flow assay to two-fold in the perfusion assay. The intra-assay variation was highest in the petri dish assay. A positive correlation between IE binding avidity and the level of binding after antibody inhibition in the petri dish assay indicate that high avidity IE binding is more difficult to inhibit. The highest binding inhibition sensitivity was found in the 96-well and petri dish assays compared to the flow and perfusion assays where binding inhibition required higher antibody titers. CONCLUSIONS: The inhibitory capacity of antibodies is not easily translated between assays and the high sensitivity of the 96-well and petri dish assays stresses the need for comparing serial dilutions of serum. Furthermore, IE binding avidity must be in the same range when comparing data from different days. There was an overall concordance in the capacity of antibody-mediated inhibition, when comparing the in vitro assays with the perfusion assay, which more closely represents in vivo conditions. Importantly the ID1-ID2a protein in a liposomal formulation, currently in a phase I trial, effectively induced antibodies that inhibited IE adhesion in placental tissue.

Placental Sequestration of Plasmodium falciparum Malaria Parasites Is Mediated by the Interaction Between VAR2CSA and Chondroitin Sulfate A on Syndecan-1.

During placental malaria, Plasmodium falciparum infected erythrocytes sequester in the placenta, causing health problems for both the mother and fetus. The specific adherence is mediated by the VAR2CSA protein, which binds to placental chondroitin sulfate (CS) on chondroitin sulfate proteoglycans (CSPGs) in the placental syncytium. However, the identity of the CSPG core protein and the cellular impact of the interaction have remain elusive. In this study we identified the specific CSPG core protein to which the CS is attached, and characterized its exact placental location. VAR2CSA pull-down experiments using placental extracts from whole placenta or syncytiotrophoblast microvillous cell membranes showed three distinct CSPGs available for VAR2CSA adherence. Further examination of these three CSPGs by immunofluorescence and proximity ligation assays showed that syndecan-1 is the main receptor for VAR2CSA mediated placental adherence. We further show that the commonly used placental choriocarcinoma cell line, BeWo, express a different set of proteoglycans than those present on placental syncytiotrophoblast and may not be the most biologically relevant model to study placental malaria. Syncytial fusion of the BeWo cells, triggered by forskolin treatment, caused an increased expression of placental CS-modified syndecan-1. In line with this, we show that rVAR2 binding to placental CS impairs syndecan-1-related Src signaling in forskolin treated BeWo cells, but not in untreated cells.

Adhesion of Plasmodium falciparum infected erythrocytes in ex vivo perfused placental tissue: a novel model of placental malaria.

BACKGROUND: Placental malaria occurs when Plasmodium falciparum infected erythrocytes sequester in the placenta. Placental parasite isolates bind to chondroitin sulphate A (CSA) by expression of VAR2CSA on the surface of infected erythrocytes, but may sequester by other VAR2CSA mediated mechanisms, such as binding to immunoglobulins. Furthermore, other parasite antigens have been associated with placental malaria. These findings have important implications for placental malaria vaccine design. The objective of this study was to adapt and describe a biologically relevant model of parasite adhesion in intact placental tissue. RESULTS: The ex vivo placental perfusion model was modified to study adhesion of infected erythrocytes binding to CSA, endothelial protein C receptor (EPCR) or a transgenic parasite where P. falciparum erythrocyte membrane protein 1 expression had been shut down. Infected erythrocytes expressing VAR2CSA accumulated in perfused placental tissue whereas the EPCR binding and the transgenic parasite did not. Soluble CSA and antibodies specific against VAR2CSA inhibited binding of infected erythrocytes. CONCLUSION: The ex vivo model provides a novel way of studying receptor-ligand interactions and antibody mediated inhibition of binding in placental malaria.

Kinetics of silica nanoparticles in the human placenta.

The potential medical applications of nanoparticles (NPs) warrant their investigation in terms of biodistribution and safety during pregnancy. The transport of silica NPs across the placenta was investigated using two models of maternal-foetal transfer in human placenta, namely, the BeWo b30 choriocarcinoma cell line and the ex vivo perfused human placenta. Nanotoxicity in BeWo cells was examined by the MTT assay which demonstrated decreased cell viability at concentrations >100 µg/mL. In the placental perfusion experiments, antipyrine crossed the placenta rapidly, with a foetal:maternal ratio of 0.97 ± 0.10 after 2 h. In contrast, the percentage of silica NPs reaching the foetal perfusate after 6 h was limited to 4.2 ± 4.9% and 4.6 ± 2.4% for 25 and 50 nm NPs, respectively. The transport of silica NPs across the BeWo cells was also limited, with an apparent permeability of only 1.54 × 10(-6) ± 1.56 × 10(-6) cm/s. Using confocal microscopy, there was visual confirmation of particle accumulation in both BeWo cells and in perfused placental tissue. Despite the low transfer of silica NPs to the foetal compartment, questions regarding biocompatibility could limit the application of unmodified silica NPs in biomedical imaging or therapy.

Pathologic evaluation of normal and perfused term placental tissue.

This study reports for the 1st time the incidence and interobserver variation of morphologic findings in a series of 34 term placentas from pregnancies with normal outcome used for perfusion studies. Histologic evaluation of placental tissue is challenging, especially when it comes to defining "normal tissue" versus "pathologic lesions." A scoring system for registration of abnormal morphologic findings was developed. Light microscopic examination was performed independently by 2 pathologists, and interobserver variation was analyzed. Findings in normal and perfused tissue were compared and selected findings were tested against success parameters from the perfusions. Finally, the criteria for frequent lesions with fair to poor interobserver variation in the nonperfused tissue were revised and reanalyzed. In the perfused tissue, the perfusion artefact "trophoblastic vacuolization," which is believed to represent dilated transtrophoblastic channels, was reproducible and significantly correlated to the perfusion marker "fetal leakage." In longer perfusions, microscopy of the perfused cotyledon revealed bacteria in the fetal vessels. This finding led to an adjustment in the perfusion protocol with addition of antibiotics to the medium. In the "normal" tissue, certain lesions were very frequent and showed only fair or poor interobserver agreement. Revised minimum criteria for these lesions were defined and found reproducible. This study has emphasized the value of pathologic examination as a supplement in placental perfusion models. Examination of the perfused cotyledon for trophoblastic vacuolization is recommended as an additional quality marker in perfusion models. The study also underlines the need for exact definitions of abnormality in frequent placental lesions.

Modelling of human transplacental transport as performed in Copenhagen, Denmark.

Placenta perfusion models are very effective when studying the placental mechanisms in order to extrapolate to real-life situations. The models are most often used to investigate the transport of substances between mother and foetus, including the potential metabolism of these. We have studied the relationships between maternal and foetal exposures to various compounds including pollutants such as polychlorinated biphenyls, polybrominated flame retardants, nanoparticles as well as recombinant human antibodies. The compounds have been studied in the human placenta perfusion model and to some extent in vitro with an established human monolayer trophoblast cell culture model. Results from our studies distinguish placental transport of substances by physicochemical properties, adsorption to placental tissue, binding to transport and receptor proteins and metabolism. We have collected data from different classes of chemicals and nanoparticles for comparisons across chemical structures as well as different test systems. Our test systems are based on human material to bypass the extrapolation from animal data. By combining data from our two test systems, we are able to rank and compare the transport of different classes of substances according to their transport ability. Ultimately, human data including measurements in cord blood contribute to the study of placental transport.

PCB concentrations and dioxin-like activity in blood samples from Danish school children and their mothers living in urban and rural areas.

Human exposure to persistent organic pollutants (POPs) is of major concern due to a diversity of adverse effects from prolonged exposure and bioaccumulation. Manufacturing of polychlorinated biphenyls (PCBs), a subgroup of POPs, has been prohibited for many decades; however, human exposure still occurs due to the persistent nature of the chemicals. The concentrations of the dioxin-like PCB congeners 105, 118 and 156 and the non-dioxin-like PCB congeners 28, 52, 101, 138, 153 and 180, p,p'-DDE, p,p'-DDT, o,p'-DDE, o,p'-DDT, HCB and ß-HCH as well as the dioxin-like activity using the AhR transactivity assay were analysed in blood samples from Danish schoolchildren and their mothers in the European framework of the DEMOCOPHES/COPHES projects. The participants were selected from an urban and a rural area, respectively. The PCB concentrations and the AhR-TEQ (TCDD toxic equivalent) were significantly higher in schoolchildren living in the urban area compared with the rural, and for AhR-TEQ, a strong correlation between the mothers and children was observed. We found a significant negative correlation between BMI and PCB concentrations in the children. Finally, in the mothers, there was a positive association between age and PCB concentration. These results show that both PCBs and dioxin-like activity can be measured as biomarkers of exposure and effects in blood samples from children and women. The results indicate that people living in urban areas may be exposed to higher concentrations of PCBs, dioxins and dioxin-like chemicals, which may lead to a greater risk of adverse effects for urban populations.