1
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Lofthouse EM, Cleal J, Lewis RM, Sengers BG. Computational Modelling of Paracellular Diffusion and OCT3 Mediated Transport of Metformin in the Perfused Human Placenta. J Pharm Sci 2023; 112:2570-2580. [PMID: 37211316 DOI: 10.1016/j.xphs.2023.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/15/2023] [Accepted: 05/15/2023] [Indexed: 05/23/2023]
Abstract
Metformin is an antidiabetic drug, increasingly prescribed in pregnancy and has been shown to cross the human placenta. The mechanisms underlying placental metformin transfer remain unclear. This study investigated the roles of drug transporters and paracellular diffusion in the bidirectional transfer of metformin across the human placental syncytiotrophoblast using placental perfusion experiments and computational modelling. 14C-metformin transfer was observed in the maternal to fetal and fetal to maternal directions and was not competitively inhibited by 5 mM unlabelled metformin. Computational modelling of the data was consistent with overall placental transfer via paracellular diffusion. Interestingly, the model also predicted a transient peak in fetal 14C-metformin release due to trans-stimulation of OCT3 by unlabelled metformin at the basal membrane. To test this hypothesis a second experiment was designed. OCT3 substrates (5 mM metformin, 5 mM verapamil and 10 mM decynium-22) added to the fetal artery trans-stimulated release of 14C-metformin from the placenta into the fetal circulation, while 5 mM corticosterone did not. This study demonstrated activity of OCT3 transporters on the basal membrane of the human syncytiotrophoblast. However, we did not detect a contribution of either OCT3 or apical membrane transporters to overall materno-fetal transfer, which could be represented adequately by paracellular diffusion in our system.
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Affiliation(s)
- Emma M Lofthouse
- Faculty of Medicine, University of Southampton, UK; Institute for Life Sciences, University of Southampton, UK
| | - Jane Cleal
- Faculty of Medicine, University of Southampton, UK; Institute for Life Sciences, University of Southampton, UK
| | - Rohan M Lewis
- Faculty of Medicine, University of Southampton, UK; Institute for Life Sciences, University of Southampton, UK
| | - Bram G Sengers
- Faculty of Engineering and Physical Sciences, University of Southampton, UK; Institute for Life Sciences, University of Southampton, UK.
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2
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Lewis RM, Baskaran H, Green J, Tashev S, Palaiologou E, Lofthouse EM, Cleal JK, Page A, Chatelet DS, Goggin P, Sengers BG. 3D visualization of trans-syncytial nanopores provides a pathway for paracellular diffusion across the human placental syncytiotrophoblast. iScience 2022; 25:105453. [DOI: 10.1016/j.isci.2022.105453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 09/02/2022] [Accepted: 10/24/2022] [Indexed: 11/13/2022] Open
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3
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Schneider H, Albrecht C, Ahmed MS, Broekhuizen M, Aengenheister L, Buerki-Thurnherr T, Danser AHJ, Gil S, Hansson SR, Greupink R, Lewis RM, Markert UR, Mathiesen L, Powles-Glover N, Wadsack C, Brownbill P. Ex vivo dual perfusion of an isolated human placenta cotyledon: Towards protocol standardization and improved inter-centre comparability. Placenta 2022; 126:83-89. [PMID: 35785693 DOI: 10.1016/j.placenta.2022.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 04/06/2022] [Accepted: 05/04/2022] [Indexed: 12/29/2022]
Abstract
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.
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Affiliation(s)
- Henning Schneider
- Dept. Obstetrics & Gynecology, Inselspital, Bern University Hospital, Switzerland.
| | - Christiane Albrecht
- Institute of Biochemistry & Molecular Medicine, University of Bern, Switzerland; Swiss National Centre of Competence in Research (NCCR) TransCure, University of Bern, Switzerland.
| | - Mahmoud S Ahmed
- Departments of Obstetrics and Gynecology and Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA.
| | - Michelle Broekhuizen
- Division of Neonatology, Department of Pediatrics, Erasmus MC, Rotterdam, the Netherlands; Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
| | - Leonie Aengenheister
- Particles-Biology Interactions, Empa, Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland.
| | - Tina Buerki-Thurnherr
- Particles-Biology Interactions, Empa, Swiss Federal Laboratories for Materials Science and Technology, St. Gallen, Switzerland.
| | - A H Jan Danser
- Division of Vascular Medicine and Pharmacology, Department of Internal Medicine, Erasmus MC, Rotterdam, the Netherlands.
| | - Sophie Gil
- University Paris Cité, Placentech®, Paris, F-75014, France.
| | - Stefan R Hansson
- Lund University, Department of Obstetrics and Gynecology, Institute of Clinical Sciences Lund, Lund University, Lund, Sweden.
| | - Rick Greupink
- Department of Pharmacology & Toxicology, Radboud University Medical Center, Nijmegen, the Netherlands.
| | | | - Udo R Markert
- Department of Obstetrics, Placenta Lab, Jena University Hospital, Jena, Germany.
| | - Line Mathiesen
- Department of Public Health, University of Copenhagen, Faculty of Health Sciences, Copenhagen, Denmark.
| | | | - Christian Wadsack
- Department of Obstetrics and Gynecology, Medical University of Graz, Graz, Austria.
| | - Paul Brownbill
- Maternal and Fetal Health Research Centre, University of Manchester, UK; Manchester Academic Health Sciences Centre, UK.
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4
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Angiolini E, Sandovici I, Coan PM, Burton GJ, Sibley CP, Fowden AL, Constância M. Deletion of the Imprinted Phlda2 Gene Increases Placental Passive Permeability in the Mouse. Genes (Basel) 2021; 12:genes12050639. [PMID: 33922969 PMCID: PMC8146920 DOI: 10.3390/genes12050639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 04/09/2021] [Accepted: 04/23/2021] [Indexed: 11/16/2022] Open
Abstract
Genomic imprinting, an epigenetic phenomenon that causes the expression of a small set of genes in a parent-of-origin-specific manner, is thought to have co-evolved with placentation. Many imprinted genes are expressed in the placenta, where they play diverse roles related to development and nutrient supply function. However, only a small number of imprinted genes have been functionally tested for a role in nutrient transfer capacity in relation to the structural characteristics of the exchange labyrinthine zone. Here, we examine the transfer capacity in a mouse model deficient for the maternally expressed Phlda2 gene, which results in placental overgrowth and a transient reduction in fetal growth. Using stereology, we show that the morphology of the labyrinthine zone in Phlda2−/+ mutants is normal at E16 and E19. In vivo placental transfer of radiolabeled solutes 14C-methyl-D-glucose and 14C-MeAIB remains unaffected at both gestational time points. However, placental passive permeability, as measured using two inert hydrophilic solutes (14C-mannitol; 14C-inulin), is significantly higher in mutants. Importantly, this increase in passive permeability is associated with fetal catch-up growth. Our findings uncover a key role played by the imprinted Phlda2 gene in modifying placental passive permeability that may be important for determining fetal growth.
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Affiliation(s)
- Emily Angiolini
- University of Cambridge Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Institute of Metabolic Science, Addenbrookes Hospital, Cambridge CB2 0QQ, UK; (E.A.); (I.S.)
- Department of Obstetrics and Gynaecology, National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge CB2 0SW, UK
- Epigenetics Programme, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Ionel Sandovici
- University of Cambridge Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Institute of Metabolic Science, Addenbrookes Hospital, Cambridge CB2 0QQ, UK; (E.A.); (I.S.)
- Department of Obstetrics and Gynaecology, National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge CB2 0SW, UK
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK; (P.M.C.); (G.J.B.); (A.L.F.)
| | - Philip M. Coan
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK; (P.M.C.); (G.J.B.); (A.L.F.)
| | - Graham J. Burton
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK; (P.M.C.); (G.J.B.); (A.L.F.)
| | - Colin P. Sibley
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9WL, UK;
- Manchester Academic Health Science Centre, St. Mary’s Hospital, Manchester University NHS Foundation Trust, Manchester M13 9WL, UK
| | - Abigail L. Fowden
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK; (P.M.C.); (G.J.B.); (A.L.F.)
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Miguel Constância
- University of Cambridge Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Institute of Metabolic Science, Addenbrookes Hospital, Cambridge CB2 0QQ, UK; (E.A.); (I.S.)
- Department of Obstetrics and Gynaecology, National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge CB2 0SW, UK
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK; (P.M.C.); (G.J.B.); (A.L.F.)
- Correspondence: ; Tel.: +44-1223-336873
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5
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Shojaei S, Ali MS, Suresh M, Upreti T, Mogourian V, Helewa M, Labouta HI. Dynamic placenta-on-a-chip model for fetal risk assessment of nanoparticles intended to treat pregnancy-associated diseases. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166131. [PMID: 33766738 DOI: 10.1016/j.bbadis.2021.166131] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/11/2021] [Accepted: 03/12/2021] [Indexed: 12/13/2022]
Abstract
Pregnant women often have to take medication either for pregnancy-related diseases or for previously existing medical conditions. Current maternal medications pose fetal risks due to off target accumulation in the fetus. Nanoparticles, engineered particles in the nanometer scale, have been used for targeted drug delivery to the site of action without off-target effects. This has opened new avenues for treatment of pregnancy-associated diseases while minimizing risks on the fetus. It is therefore instrumental to study the potential transfer of nanoparticles from the mother to the fetus. Due to limitations of in vivo and ex vivo models, an in vitro model mimicking the in vivo situation is essential. Placenta-on-a-chip provides a microphysiological recapitulation of the human placenta. Here, we reviewed the fetal risks associated with current therapeutic approaches during pregnancy, analyzed the advantages and limitations of current models used for nanoparticle assessment, and highlighted the current need for using dynamic placenta-on-a-chip models for assessing the safety of novel nanoparticle-based therapies during pregnancy.
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Affiliation(s)
- Shahla Shojaei
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.
| | - Moustafa S Ali
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada; Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, Canada.
| | - Madhumita Suresh
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.
| | - Tushar Upreti
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.
| | - Victoria Mogourian
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada.
| | - Michael Helewa
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Manitoba, Winnipeg, Canada.
| | - Hagar I Labouta
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Canada; Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, Canada; Biomedical Engineering, University of Manitoba, Winnipeg, Canada; Faculty of Pharmacy, Alexandria University, Alexandria, Egypt.
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6
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Zarriello S, Tuazon JP, Corey S, Schimmel S, Rajani M, Gorsky A, Incontri D, Hammock BD, Borlongan CV. Humble beginnings with big goals: Small molecule soluble epoxide hydrolase inhibitors for treating CNS disorders. Prog Neurobiol 2018; 172:23-39. [PMID: 30447256 DOI: 10.1016/j.pneurobio.2018.11.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 10/06/2018] [Accepted: 11/09/2018] [Indexed: 12/17/2022]
Abstract
Soluble epoxide hydrolase (sEH) degrades epoxides of fatty acids including epoxyeicosatrienoic acid isomers (EETs), which are produced as metabolites of the cytochrome P450 branch of the arachidonic acid pathway. EETs exert a variety of largely beneficial effects in the context of inflammation and vascular regulation. sEH inhibition is shown to be therapeutic in several cardiovascular and renal disorders, as well as in peripheral analgesia, via the increased availability of anti-inflammatory EETs. The success of sEH inhibitors in peripheral systems suggests their potential in targeting inflammation in the central nervous system (CNS) disorders. Here, we describe the current roles of sEH in the pathology and treatment of CNS disorders such as stroke, traumatic brain injury, Parkinson's disease, epilepsy, cognitive impairment, dementia and depression. In view of the robust anti-inflammatory effects of stem cells, we also outlined the potency of stem cell treatment and sEH inhibitors as a combination therapy for these CNS disorders. This review highlights the gaps in current knowledge about the pathologic and therapeutic roles of sEH in CNS disorders, which should guide future basic science research towards translational and clinical applications of sEH inhibitors for treatment of neurological diseases.
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Affiliation(s)
- Sydney Zarriello
- Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL, 33612, United States
| | - Julian P Tuazon
- Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL, 33612, United States
| | - Sydney Corey
- Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL, 33612, United States
| | - Samantha Schimmel
- Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL, 33612, United States
| | - Mira Rajani
- Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL, 33612, United States
| | - Anna Gorsky
- Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL, 33612, United States
| | - Diego Incontri
- Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL, 33612, United States
| | - Bruce D Hammock
- Department of Entomology & UCD Comprehensive Cancer Center, NIEHS-UCD Superfund Research Program, University of California - Davis, United States.
| | - Cesar V Borlongan
- Center of Excellence for Aging and Brain Repair, University of South Florida College of Medicine, 12901 Bruce B Downs Blvd, Tampa, FL, 33612, United States.
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7
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Desforges M, Rogue A, Pearson N, Rossi C, Olearo E, Forster R, Lees M, Sebire NJ, Greenwood SL, Sibley CP, David AL, Brownbill P. In Vitro Human Placental Studies to Support Adenovirus-Mediated VEGF-D ΔNΔC Maternal Gene Therapy for the Treatment of Severe Early-Onset Fetal Growth Restriction. HUM GENE THER CL DEV 2018; 29:10-23. [PMID: 29228803 DOI: 10.1089/humc.2017.090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Severe fetal growth restriction (FGR) affects 1 in 500 pregnancies, is untreatable, and causes serious neonatal morbidity and death. Reduced uterine blood flow (UBF) is one cause. Transduction of uterine arteries in normal and FGR animal models using an adenovirus (Ad) encoding VEGF isoforms increases UBF and improves fetal growth in utero. Understanding potential adverse consequences of this therapy before first-in-woman clinical application is essential. The aims of this study were to determine whether Ad.VEGF-DΔNΔC (1) transfers across the human placental barrier and (2) affects human placental morphology, permeability and primary indicators of placental function, and trophoblast integrity. Villous explants from normal term human placentas were treated with Ad.VEGF-DΔNΔC (5 × 107-10 virus particles [vp]/mL), or virus formulation buffer (FB). Villous structural integrity (hematoxylin and eosin staining) and tissue accessibility (LacZ immunostaining) were determined. Markers of endocrine function (human chorionic gonadotropin [hCG] secretion) and cell death (lactate dehydrogenase [LDH] release) were assayed. Lobules from normal and FGR pregnancies underwent ex vivo dual perfusion with exposure to 5 × 1010 vp/mL Ad.VEGF-DΔNΔC or FB. Perfusion resistance, para-cellular permeability, hCG, alkaline phosphatase, and LDH release were measured. Ad.VEGF-DΔNΔC transfer across the placental barrier was assessed by quantitative polymerase chain reaction in DNA extracted from fetal-side venous perfusate, and by immunohistochemistry in fixed tissue. Villous explant structural integrity and hCG secretion was maintained at all Ad.VEGF-DΔNΔC doses. Ad.VEGF-DΔNΔC perfusion revealed no effect on placental permeability, fetoplacental vascular resistance, hCG secretion, or alkaline phosphatase release, but there was a minor elevation in maternal-side LDH release. Viral vector tissue access in both explant and perfused models was minimal, and the vector was rarely detected in the fetal venous perfusate and at low titer. Ad.VEGF-DΔNΔC did not markedly affect human placental integrity and function in vitro. There was limited tissue access and transfer of vector across the placental barrier. Except for a minor elevation in LDH release, these test data did not reveal any toxic effects of Ad.VEGF-DΔNΔC on the human placenta.
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Affiliation(s)
- Michelle Desforges
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, University of Manchester , Manchester, United Kingdom .,2 St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust , Manchester Academic Health Science Centre, Manchester, United Kingdom
| | | | - Nick Pearson
- 4 Pharmaceutical Sciences, pRED, F Hoffmann-La Roche , Basel, Switzerland
| | - Carlo Rossi
- 5 Magnus Growth , London, United Kingdom .,6 Institute for Women's Health, University College London (UCL) , London, United Kingdom
| | - Elena Olearo
- 6 Institute for Women's Health, University College London (UCL) , London, United Kingdom
| | | | - Mark Lees
- 5 Magnus Growth , London, United Kingdom
| | - Neil J Sebire
- 7 Institute of Child Health, University College London (UCL) , London, United Kingdom
| | - Susan L Greenwood
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, University of Manchester , Manchester, United Kingdom .,2 St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust , Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Colin P Sibley
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, University of Manchester , Manchester, United Kingdom .,2 St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust , Manchester Academic Health Science Centre, Manchester, United Kingdom
| | - Anna L David
- 6 Institute for Women's Health, University College London (UCL) , London, United Kingdom
| | - Paul Brownbill
- 1 Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, University of Manchester , Manchester, United Kingdom .,2 St. Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust , Manchester Academic Health Science Centre, Manchester, United Kingdom
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8
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Swardfager W, Hennebelle M, Yu D, Hammock BD, Levitt AJ, Hashimoto K, Taha AY. Metabolic/inflammatory/vascular comorbidity in psychiatric disorders; soluble epoxide hydrolase (sEH) as a possible new target. Neurosci Biobehav Rev 2018; 87:56-66. [PMID: 29407524 DOI: 10.1016/j.neubiorev.2018.01.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 01/17/2018] [Accepted: 01/21/2018] [Indexed: 02/06/2023]
Abstract
The common and severe psychiatric disorders, including major depressive disorder (MDD) and bipolar disorder (BD), are associated with inflammation, oxidative stress and changes in peripheral and brain lipid metabolism. Those pathways are implicated in the premature development of vascular and metabolic comorbidities, which account for considerable morbidity and mortality, including increased dementia risk. During endoplasmic reticulum stress, the soluble epoxide hydrolase (sEH) enzyme converts anti-inflammatory fatty acid epoxides generated by cytochrome p450 enzymes into their corresponding and generally less anti-inflammatory, or even pro-inflammatory, diols, slowing the resolution of inflammation. The sEH enzyme and its oxylipin products are elevated post-mortem in MDD, BD and schizophrenia. Preliminary clinical data suggest that oxylipins increase with symptoms in seasonal MDD and anorexia nervosa, requiring confirmation in larger studies and other cohorts. In rats, a soluble sEH inhibitor mitigated the development of depressive-like behaviors. We discuss sEH inhibitors under development for cardiovascular diseases, post-ischemic brain injury, neuropathic pain and diabetes, suggesting new possibilities to address the mood and cognitive symptoms of psychiatric disorders, and their most common comorbidities.
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Affiliation(s)
- W Swardfager
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, Canada; Department of Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Pharmacology & Toxicology, Faculty of Medicine, University of Toronto, Toronto, Canada; Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, Canada; University Health Network Toronto Rehabilitation Institute, Toronto, Canada.
| | - M Hennebelle
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA
| | - D Yu
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, Canada; Department of Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Canada; Department of Pharmacology & Toxicology, Faculty of Medicine, University of Toronto, Toronto, Canada; Canadian Partnership for Stroke Recovery, Sunnybrook Research Institute, Toronto, Canada
| | - B D Hammock
- Department of Entomology and Nematology and Comprehensive Cancer Center UCDMC, University of California, Davis, CA, USA
| | - A J Levitt
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, Canada; Department of Psychiatry, Sunnybrook Health Sciences Centre, Toronto, Canada
| | - K Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | - A Y Taha
- Department of Food Science and Technology, College of Agriculture and Environmental Sciences, University of California, Davis, CA, USA
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9
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Sibley CP, Brownbill P, Glazier JD, Greenwood SL. Knowledge needed about the exchange physiology of the placenta. Placenta 2018; 64 Suppl 1:S9-S15. [PMID: 29370939 DOI: 10.1016/j.placenta.2018.01.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/09/2018] [Accepted: 01/10/2018] [Indexed: 01/30/2023]
Abstract
There is now a basic understanding of the driving forces and mechanisms underlying rates of solute exchange across the placenta but there are still major gaps in knowledge. Here we summarise this basic understanding, whilst highlighting gaps in knowledge. We then focus on two particular areas where more knowledge is needed: (1) the electrical potential difference (PD) across the placenta and (2) the paracellular permeability of the placenta to hydrophilic solutes. In many species a PD has been recorded between a catheter in a maternal blood vessel and one in a fetal vessel. However, the key question is whether this PD is the same as that across the placental exchange barrier. We addressed this in the human placenta using microelectrodes to measure the PD in isolated villi in vitro; the transtrophoblast PD so measured had a median value of -3 mV (range 0-15 mV). There have been no subsequent studies to validate this measurement. The syncytiotrophoblast of haemochorial placentas lacks any obvious extracellular water filled paracellular space between the syncytial nuclei. However, in mouse, rat, guinea pig and human there is an inverse relationship between the rate of diffusion of inert hydrophilic solutes across the placenta and their molecular size. The simplest explanation is that a paracellular route exists but its morphological identity is still uncertain. Areas of syncytial denudation could provide a paracellular route but this has not been proven. Answers to these and similar questions are required to fully understand the exchange physiology of the normal placenta and how this is affected in pathology.
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Affiliation(s)
- Colin P Sibley
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK; St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK.
| | - Paul Brownbill
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK; St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK
| | - Jocelyn D Glazier
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK; St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK
| | - Susan L Greenwood
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester, UK; St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK
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10
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Pereira FTV, Oliveira LJ, Barreto RDSN, Mess A, Perecin F, Bressan FF, Mesquita LG, Miglino MA, Pimentel JR, Neto PF, Meirelles FV. Fetal-maternal interactions in the synepitheliochorial placenta using the eGFP cloned cattle model. PLoS One 2013; 8:e64399. [PMID: 23724045 PMCID: PMC3665810 DOI: 10.1371/journal.pone.0064399] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 04/12/2013] [Indexed: 02/06/2023] Open
Abstract
Background To investigate mechanisms of fetal-maternal cell interactions in the bovine placenta, we developed a model of transgenic enhanced Green Fluorescent Protein (t-eGFP) expressing bovine embryos produced by nuclear transfer (NT) to assess the distribution of fetal-derived products in the bovine placenta. In addition, we searched for male specific DNA in the blood of females carrying in vitro produced male embryos. Our hypothesis is that the bovine placenta is more permeable to fetal-derived products than described elsewhere. Methodology/Principal Findings Samples of placentomes, chorion, endometrium, maternal peripheral blood leukocytes and blood plasma were collected during early gestation and processed for nested-PCR for eGFP and testis-specific Y-encoded protein (TSPY), western blotting and immunohistochemistry for eGFP detection, as well as transmission electron microscopy to verify the level of interaction between maternal and fetal cells. TSPY and eGFP DNA were present in the blood of cows carrying male pregnancies at day 60 of pregnancy. Protein and mRNA of eGFP were observed in the trophoblast and uterine tissues. In the placentomes, the protein expression was weak in the syncytial regions, but intense in neighboring cells on both sides of the fetal-maternal interface. Ultrastructurally, our samples from t-eGFP expressing NT pregnancies showed to be normal, such as the presence of interdigitating structures between fetal and maternal cells. In addition, channels-like structures were present in the trophoblast cells. Conclusions/Significance Data suggested that there is a delivery of fetal contents to the maternal system on both systemic and local levels that involved nuclear acids and proteins. It not clear the mechanisms involved in the transfer of fetal-derived molecules to the maternal system. This delivery may occur through nonclassical protein secretion; throughout transtrophoblastic-like channels and/or by apoptotic processes previously described. In conclusion, the bovine synepitheliochorial placenta displays an intimate fetal-maternal interaction, similar to other placental types for instance human and mouse.
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Affiliation(s)
| | - Lilian J. Oliveira
- Department of Veterinary Medicine, College of Animal Sciences and Food Engineering, University of São Paulo, Pirassununga, Brazil
- * E-mail:
| | - Rodrigo da Silva Nunes Barreto
- Department of Surgery - Anatomy of Domestic and Wild Animals - College of Veterinary Medicine and Animal Sciences - University of São Paulo, Butantã, Brazil
| | - Andrea Mess
- Department of Surgery - Anatomy of Domestic and Wild Animals - College of Veterinary Medicine and Animal Sciences - University of São Paulo, Butantã, Brazil
| | - Felipe Perecin
- Department of Veterinary Medicine, College of Animal Sciences and Food Engineering, University of São Paulo, Pirassununga, Brazil
| | - Fabiana Fernandes Bressan
- Department of Veterinary Medicine, College of Animal Sciences and Food Engineering, University of São Paulo, Pirassununga, Brazil
| | - Ligia Garcia Mesquita
- Department of Animal Nutrition and Production - College of Veterinary Medicine and Animal Sciences - University of São Paulo, Butantã, Brazil
| | - Maria Angelica Miglino
- Department of Surgery - Anatomy of Domestic and Wild Animals - College of Veterinary Medicine and Animal Sciences - University of São Paulo, Butantã, Brazil
| | - José RodrigoValim Pimentel
- Department of Veterinary Medicine, College of Animal Sciences and Food Engineering, University of São Paulo, Pirassununga, Brazil
| | - Paulo Fantinato Neto
- Department of Surgery - Anatomy of Domestic and Wild Animals - College of Veterinary Medicine and Animal Sciences - University of São Paulo, Butantã, Brazil
| | - Flávio Vieira Meirelles
- Department of Veterinary Medicine, College of Animal Sciences and Food Engineering, University of São Paulo, Pirassununga, Brazil
- Center for Cell-based Theraphy, College of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
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11
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Chui A, Evseenko D, Brennecke S, Keelan J, Kalionis B, Murthi P. Homeobox gene Distal-less 3 (DLX3) is a regulator of villous cytotrophoblast differentiation. Placenta 2011; 32:745-51. [DOI: 10.1016/j.placenta.2011.07.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 07/06/2011] [Accepted: 07/07/2011] [Indexed: 01/07/2023]
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12
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Abstract
Abstract
A system of dual perfusion of an isolated lobule of term human placenta was used as a model to study the transfer of heparin from maternal to foetal circulation. The metabolic viability of the system was assessed by measuring β-HCG and alkaline phosphatase levels in both maternal and foetal perfusates. Creatinine and antipyrine were used as markers to determine juxtaposition of the maternal and foetal circulations. Results of this study indicate that following administration of a single bolus dose of heparin into the maternal circulation, its concentration declined slowly from 99·01 ±2·98 at 15 min to 97·23 ±4·12% and transfer of heparin in the foetal circulation was linear and increased from 0·10% ±0·05% at 15 min to 0·46 ±0·19% over a period of 120 min. The maternal (MAUC) and foetal (FAUC) concentration-time integrals were found to be 70160 ± 1332 and 340 ± 30 int. units min mL−1, respectively. Placental permeability of heparin and creatinine, calculated as the ratio of foetal concentration to the integral maternal–foetal concentration difference, was 8·65 × 10−5 ± 0·80 × 10−5 and 0·033 ±0006 mL min−1 g−1 of perfused placental weight, respectively. These data suggest that heparin was transferred from the maternal to the foetal circulation in small quantities.
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Affiliation(s)
- R Bajoria
- Department of Obstetrics and Gynaecology, Charing Cross and Westminster Medical School, West London Hospital, UK
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13
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Bhattacharjee J, Ietta F, Giacomello E, Bechi N, Romagnoli R, Fava A, Paulesu L. Expression and localization of ATP binding cassette transporter A1 (ABCA1) in first trimester and term human placenta. Placenta 2010; 31:423-30. [PMID: 20338636 DOI: 10.1016/j.placenta.2010.02.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 02/22/2010] [Accepted: 02/23/2010] [Indexed: 01/23/2023]
Abstract
ATP binding cassette transporter A1 (ABCA1) is a membrane transporter which performs cellular efflux of cholesterol and phospholipid. ABCA1's cholesterol transporting role in human placenta appears to be crucial for normal fetal development. Despite the critical importance of cholesterol in fetal development, expression of ABCA1 in the human placenta throughout gestation and its specific cellular localization have not been known yet. We therefore investigated ABCA1 expression in human placenta at first trimester and term by western blot and quantitative real-time PCR (qRT-PCR) analysis. Furthermore, its localization was investigated by immunohistochemistry and confocal microscopy. Expression of ABCA1 did not differ significantly between first trimester and term placenta at both protein and mRNA levels. Immunohistochemical data demonstrated that ABCA1 was widely localized in the villous and extravillous cytotrophoblast as well as in some stromal and endothelial cells. Confocal microscopy imaging data showed that ABCA1 was localized largely at the basolateral and to some extent at the apical side of first trimester villous cytotrophoblast cell membranes. Placental expression of ABCA1 throughout the gestation and its specific cellular localization indicate that this transporter may play an important role in materno-fetal cholesterol transfer.
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Affiliation(s)
- J Bhattacharjee
- Department of Physiology, University of Siena, Via A. Moro, 53100 Siena, Italy
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14
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Chu M, Wu Q, Yang H, Yuan R, Hou S, Yang Y, Zou Y, Xu S, Xu K, Ji A, Sheng L. Transfer of quantum dots from pregnant mice to pups across the placental barrier. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2010; 6:670-678. [PMID: 20143348 DOI: 10.1002/smll.200902049] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Fluorescent quantum dots (QDs) have great potential for in vivo biomedical imaging and diagnostic applications. However, these nanoparticles are composed of heavy metals and are very small in diameter, and their possible toxicity must therefore be considered. As yet, no studies have reported the transfer of QDs between mother and fetus. The transfer of CdTe/CdS QDs of different sizes and dosages, and with different outer capping materials, from pregnant mice to fetuses is investigated. It is shown that QDs may be transferred from female mice to their fetuses across the placental barrier. Smaller QDs are more easily transferred than larger QDs and the number of QDs transferred increases with increasing dosage. Capping with an inorganic silica shell or organic polyethylene glycol reduces QD transfer but does not eliminate it. These results suggest that the clinical utility of QDs could be limited in pregnant women.
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Affiliation(s)
- Maoquan Chu
- School of Life Science and Technology Tongji University, Shanghai 200092, PR China.
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15
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Coan PM, Fowden AL, Constancia M, Ferguson-Smith AC, Burton GJ, Sibley CP. Disproportional effects of Igf2 knockout on placental morphology and diffusional exchange characteristics in the mouse. J Physiol 2008; 586:5023-32. [PMID: 18755750 DOI: 10.1113/jphysiol.2008.157313] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Both complete knockout of the Igf2 gene (Igf2null(+/-)) and knockout of its placental specific transcript alone (Igf2P0(+/-)) lead to fetal growth restriction in mice. However, in the Igf2null(+/-) this growth restriction occurs concurrently in gestation with placental growth restriction, whereas, placental growth restriction precedes fetal growth restriction in the Igf2P0(+/-) mouse. Previous studies have shown that the Igf2P0(+/-) placenta has proportionate reductions in its cellular compartments and its diffusional exchange characteristics. Yet, nothing is known about the structural development or diffusional exchange characteristics of the Igf2null(+/-) mouse. Hence, this study compares the structural properties (using stereology) and diffusional exchange characteristics (using measurement of permeability-surface area product, P.S, of three inert hydrophilic tracers) of the Igf2null(+/-) and the Igf2P0(+/-) placenta to identify the role of Igf2 in the development of the labyrinthine exchange membrane and its functional consequences. Our data show disproportionate effects of complete Igf2 ablation on the compartments of the placenta, not seen when the placental-specific transcript alone is deleted. Furthermore, although the theoretical diffusing capacity (calculated from the stereological data) of the Igf2null(+/-) placenta was reduced relative to control, there was no effect of the complete knockout on permeability surface area available for small hydrophilic tracers. This is in contrast to the Igf2P0(+/-) placenta, where theoretical diffusion capacity and P.S values were reduced similarly. Total ablation of the Igf2 gene from the fetoplacental unit in the mouse therefore results in a disproportionate growth of placental compartments whereas, deleting the placental specific transcript of Igf2 alone results in proportional placental growth restriction. Thus, placental phenotype depends on the degree of Igf2 gene ablation and the interplay between placental and fetal Igf2 in the mouse.
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Affiliation(s)
- P M Coan
- Department of Physiology, Development & Neuroscience, University of Cambridge, Cambridge, UK.
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16
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Shintaku K, Arima Y, Dan Y, Takeda T, Kogushi K, Tsujimoto M, Nagata H, Satoh S, Tsukimori K, Nakano H, Hori S, Ohtani H, Sawada Y. Kinetic analysis of the transport of salicylic acid, a nonsteroidal anti-inflammatory drug, across human placenta. Drug Metab Dispos 2007; 35:772-8. [PMID: 17312018 DOI: 10.1124/dmd.106.013029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to develop a pharmacokinetic model to describe the transplacental transfer of drugs, based on the human placental perfusion study. The maternal and fetal sides of human placentas were perfused with salicylic acid together with antipyrine, a passive diffusion marker. The drug concentration in the placental tissue was determined at the end of perfusion. A compartment model consisting of maternal space, fetal intravascular space, and placental tissue was fitted to the observed concentration profiles of salicylic acid in the maternal and fetal effluents. The developed model could adequately explain the concentration profiles of salicylic acid in the effluents with influx clearances from maternal and fetal perfusates to placental tissue of 0.0407 and 0.0813 ml/min/g cotyledon and efflux rate constants from placental tissue to maternal and fetal perfusates (k2 and k3) of 0.0238 and 0.176 min(-1), respectively. The kinetics of antipyrine was adequately described by assuming rapid equilibrium between fetal perfusate and placental tissue compartments. The influx plasma clearance from the maternal side (K''1) in humans was estimated by taking into account the protein binding. The K''1/k2 value of salicylic acid was 1.07 ml/g cotyledon and was larger than that of antipyrine (0.642 ml/g cotyledon). We evaluated the transplacental transfer kinetics of salicylic acid by human placental perfusion study with various perfusion protocols. Based on the data obtained, we developed a pharmacokinetic model, which should enable us to estimate the influx profile of drugs into umbilical arterial blood from the maternal plasma concentration profile.
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Affiliation(s)
- Kyohei Shintaku
- Department of Medico-Pharmaceutical Sciences, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
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17
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Dahlgren J, Samuelsson AM, Jansson T, Holmäng A. Interleukin-6 in the maternal circulation reaches the rat fetus in mid-gestation. Pediatr Res 2006; 60:147-51. [PMID: 16864694 DOI: 10.1203/01.pdr.0000230026.74139.18] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Maternal systemic infection during pregnancy may expose the fetus to infectious agents and high levels of mediators of the resulting inflammatory response, such as IL-6 (IL-6). Increased fetal and maternal levels of IL-6 have been associated with adverse neonatal outcome but might also stress the fetus and contribute to cardiovascular and neuroendocrine dysfunction in adulthood. It is unclear whether interleukins cross the placental barrier, although this matter has been little studied. The aim of this study was therefore to investigate if IL-6 administered to pregnant rats in vivo is transferred to the fetus. We injected 125I IL-6 i.v. to pregnant dams at gestation day 11-13 (mid-gestation) or 17-19 (late gestation). We found 125I-IL-6 in the exposed fetuses as well as in amniotic fluids. Fetal 125I-IL-6 levels were markedly higher in animals injected in mid-gestation compared with late pregnancy (p < 0.01). This difference was mirrored in a 15-fold higher unidirectional materno-fetal clearance for 125I-IL-6 in mid-gestation (p < 0.01). We conclude that the permeability of the rat placental barrier to IL-6 is much higher in mid-gestation than in late pregnancy. Maternally derived IL-6 may directly induce fetal injury but also stimulate the release of fetal stress hormones resulting in stimuli or insults in neuroendocrine structures and hormonal axes which might lead to disease at adult age.
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Affiliation(s)
- Jovanna Dahlgren
- Göteborg Pediatric Growth Research Center, Institute for the Health of Women and Children, Queen Silvia Childrens Hospital, Göteborg, Sweden.
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18
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Liévano S, Alarcón L, Chávez-Munguía B, González-Mariscal L. Endothelia of term human placentae display diminished expression of tight junction proteins during preeclampsia. Cell Tissue Res 2006; 324:433-48. [PMID: 16508790 DOI: 10.1007/s00441-005-0135-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Accepted: 11/22/2005] [Indexed: 01/20/2023]
Abstract
This study explores the molecular composition of the tight junction (TJ) in human term placenta from normal women and from patients with preeclampsia, a hypertensive disorder of pregnancy. Maternal endothelial dysfunction is a critical characteristic of preeclampsia; hence, we have analyzed its impact on placental vessels. The study concentrates on the TJ because this structure regulates the sealing of the paracellular route. We have found that, in placental endothelial vessels, TJ components include the peripheral protein ZO-1 and the integral proteins occludin and claudins 1, 3, and 5. During preeclampsia, the amounts of occludin and ZO-1 exhibit no significant variation, whereas those of claudins 1, 3, and 5 diminish, suggesting the presence of leakier TJs in the endothelia of the preeclamptic placenta, possibly in response to the decreased perfusion of this organ during preeclampsia. We have unexpectedly found that, in normal placentae, the multinucleated syncytiotrophoblast layer displays claudin 4 at the basal surface of the plasma membrane, and claudin 16 along the apical and basolateral surfaces. The presence of membrane-lined channels that cross the syncytiotrophoblast constituting a paracellular pathway has been determined by transmission electron microscopy and by the co-immunolocalization of claudin 16 with the plasma membrane proteins Na+K+-ATPase and GP135. Since claudin 16 functions as a paracellular channel for Mg2+, its diffuse pattern in preeclamptic placentae suggests the altered paracellular transport of Mg2+ between the maternal blood and the placental tissue.
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Affiliation(s)
- Samuel Liévano
- Gynecology and Obstetrics Hospital, La Raza Medical Center, Mexican Institute of Social Security (IMSS), México D.F., Mexico
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19
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Koizumi N, Mizuguchi H, Kondoh M, Fujii M, Nakanishi T, Utoguchi N, Watanabe Y. Efficient Gene Transfer into Differentiated Human Trophoblast Cells with Adenovirus Vector Containing RGD Motif in the Fiber Protein. Biol Pharm Bull 2006; 29:1297-9. [PMID: 16755039 DOI: 10.1248/bpb.29.1297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previously we reported fiber-modified adenovirus (Ad) vectors containing the Arg-Gly-Asp (RGD) motif on the HI loop of the fiber knob (Ad-RGD vectors) have high gene transfer efficacy into some human trophoblast cell lines. In the current study, we investigate transgene activity of Ad-RGD during differentiation of human cytotrophoblast BeWo cells into syncytiotrophoblast-like cells. Although cellular differentiation into syncytiotrophoblast cells was followed by a decrease in the coxsackievirus and adenovirus receptor levels on the cell membrane, the alphaVbeta3 and alphaVbeta5 integrin levels did not change. Conventional adenovirus vector had lower transduction activity in the differentiated cells than non-differentiated cells. In contrast, Ad-RGD vector had no influence on differentiation and had a ca. 2-5 fold higher transduction activity than that of the conventional Ad vector. Thus, Ad-RGD vector can be a powerful tool for gene transfer experiments in syncytiotrophoblast cells.
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Affiliation(s)
- Naoya Koizumi
- Laboratory of Gene Transfer and Regulation, National Institute of Biomedical Innovation, Osaka, Japan
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20
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Asano N, Kondoh M, Ebihara C, Fujii M, Nakanishi T, Soares MJ, Nakashima E, Tanaka K, Sato M, Watanabe Y. Expression profiles of zinc transporters in rodent placental models. Toxicol Lett 2004; 154:45-53. [PMID: 15475177 DOI: 10.1016/j.toxlet.2004.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Revised: 07/02/2004] [Accepted: 07/02/2004] [Indexed: 12/01/2022]
Abstract
Zinc is a vital metal that is a structural and functional component of many proteins. The precise mechanism of zinc transport in the placenta remains unclear. In this study, we investigated the expression of zinc transporters (ZnTs) in the mouse placenta and in two rat trophoblast cell lines, TR-TBT cells, which are syncytiotrophoblast cells of the labyrinth zone, and Rcho-1 cells, which retain trophoblast cell features and differentiate into trophoblast giant cells of the junctional zone. All of the ZnTs that have been identified in mice (ZnT1-7) were detected in the mouse placenta by RT-PCR. The expression profiles of ZnTs in the placenta during pregnancy were different. The mRNA levels of ZnTs, with the exception of ZnT7, did not change during pregnancy. The ZnT7 mRNA level in placenta was elevated during pregnancy. In TR-TBT cells, ZnT1, ZnT3 and ZnT4 were detected by RT-PCR analysis. In Rcho-1 cells, all of the ZnTs that have been identified in rats (ZnT1-4) were detected by RT-PCR analysis. There were no differences between the mRNA expression levels of ZnT family members in undifferentiated Rcho-1 cells and differentiated Rcho-1 cells. This is the first report of expression profiles of ZnTs during differentiation of the placenta in the mouse placenta and rat placental cell models.
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Affiliation(s)
- Nagayoshi Asano
- Department of Biopharmaceutics and Pharmaceutics, Showa Pharmaceutical University, Tokyo 194-8543, Japan
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21
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Sibley CP, Coan PM, Ferguson-Smith AC, Dean W, Hughes J, Smith P, Reik W, Burton GJ, Fowden AL, Constância M. Placental-specific insulin-like growth factor 2 (Igf2) regulates the diffusional exchange characteristics of the mouse placenta. Proc Natl Acad Sci U S A 2004; 101:8204-8. [PMID: 15150410 PMCID: PMC419581 DOI: 10.1073/pnas.0402508101] [Citation(s) in RCA: 208] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Indexed: 01/24/2023] Open
Abstract
Restricted fetal growth is associated with postnatal mortality and morbidity and may be directly related to alterations in the capacity of the placenta to supply nutrients. We proposed previously that imprinted genes can regulate nutrient supply by the placenta. Here, we tested the hypothesis that the insulin-like growth factor 2 gene (Igf2) transcribed from the placental-specific promoter (P0) regulates the development of the diffusional permeability properties of the mouse placenta. Using mice in which placental-specific Igf2 had been deleted (P0), we measured the transfer in vivo of three inert hydrophilic solutes of increasing size (14C-mannitol, 51CrEDTA, and 14C-inulin). At embryonic day 19, placental and fetal weights in P0 conceptuses were reduced to 66% and 76%, respectively, of wild type. In P0 mutants, the permeability.surface area product for the tracers at this stage of development was 68% of that of controls; this effect was independent of tracer size. Stereological analysis of histological sections revealed the surface area of the exchange barrier in the labyrinth of the mouse placenta to be reduced and thickness increased in P0 fetuses compared to wild type. As a result, the average theoretical diffusing capacity in P0 knockout placentas was dramatically reduced to 40% of that of wild-type placentas. These data show that placental Igf2 regulates the development of the diffusional exchange characteristics of the mouse placenta. This provides a mechanism for the role of imprinted genes in controlling placental nutrient supply and fetal growth. Altered placental Igf2 could be a cause of idiopathic intrauterine growth restriction in the human.
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Affiliation(s)
- C P Sibley
- Academic Unit of Child Health, Medical School, University of Manchester, St. Mary's Hospital, Manchester M13 OJH, United Kingdom.
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22
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Koizumi N, Mizuguchi H, Kondoh M, Fujii M, Hayakawa T, Watanabe Y. Efficient Gene Transfer into Human Trophoblast Cells with Adenovirus Vector Containing Chimeric Type 5 and 35 Fiber Protein. Biol Pharm Bull 2004; 27:2046-8. [PMID: 15577231 DOI: 10.1248/bpb.27.2046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recombinant adenovirus (Ad) vectors based on Ad type 5 have been widely used for gene transfer experiments. Conventional Ad type 5 vectors have a narrow range of tropism and are limited by the size of the transgene that can be packaged. To overcome these limitations, we previously developed an Ad vector (Ad5/35 vector) containing a chimeric Ad type 5 and 35 fiber protein. In the current study, we evaluated the ability of the Ad5/35 vector to transfer genes into human trophoblast cell lines (JAR, JEG-3 and BeWo cells), which are used as in vitro models of human placenta. We compared the gene transfer efficiency of Ad5/35 to that of conventional Ad vector. We found that expression of CD46, which are receptors for Ad5/35 vector, are higher than that of coxsackievirus and adenovirus receptor in all 3 trophoblast cell lines, as determined by flow cytometry. Next, we compared the transducing activity of Ad5 vector and Ad5/35 vector that each expressed luciferase as a reporter gene. Ad5/35 vector had greater gene transfer activity than the conventional Ad vector in all 3 trophoblast cell lines (1.82-fold in JAR cells, 5.37-fold in BeWo cells, 6.11-fold in JEG-3 cells). Thus, Ad vector that contains chimeric type 5 and 35 fiber protein can be a powerful tool for gene transfer experiments in human trophoblast cell lines.
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Affiliation(s)
- Naoya Koizumi
- Department of Pharmaceutics and Biopharmaceutics, Showa Pharmaceutical University, Machida, Tokyo, Japan
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Schmid KE, Davidson WS, Myatt L, Woollett LA. Transport of cholesterol across a BeWo cell monolayer: implications for net transport of sterol from maternal to fetal circulation. J Lipid Res 2003; 44:1909-18. [PMID: 12897187 DOI: 10.1194/jlr.m300126-jlr200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The placental transport of various compounds, such as glucose and fatty acids, has been well studied. However, the transport of cholesterol, a sterol essential for proper fetal development, remains undefined in the placenta. Therefore, the purpose of these studies was to examine the transport of cholesterol across a placental monolayer and its uptake by various cholesterol acceptors. BeWo cells, which originated from a human choriocarcinoma, were grown on transwells for 3 days to form a confluent monolayer. The apical side of the cells was radiolabeled with either free cholesterol or LDL cholesteryl ester. After 24 h, the radiolabel was removed and cholesterol acceptors were added to the basolateral chamber. Cholesterol was found to be taken up by the apical surface of the placental monolayer, transported to the basolateral surface of the cell, and effluxed to fetal human serum, fetal HDL, or phospholipid vesicles, but not to apolipoprotein A-I. In addition, increasing the cellular cholesterol concentration further increased the amount of cholesterol transported to the basolateral acceptors. These are the first studies to demonstrate the movement of cholesterol across a placental cell from the maternal circulation (apical side) to the fetal circulation (basolateral side).
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Affiliation(s)
- Kara E Schmid
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
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Takahashi T, Utoguchi N, Takara A, Yamamoto N, Nakanishi T, Tanaka K, Audus KL, Watanabe Y. Carrier-mediated transport of folic acid in BeWo cell monolayers as a model of the human trophoblast. Placenta 2001; 22:863-9. [PMID: 11718574 DOI: 10.1053/plac.2001.0742] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Using cultured BeWo cells as a model of human trophoblast, we investigated whether carrier-mediated transport of folic acid occurs. BeWo cells, which were derived from human choriocarcinoma, were cultured on a tissue culture plate or in a permeation chamber. When the cells reached confluence, drug uptake or transport experiments were performed. The uptake of [(3)H]folic acid by BeWo cells occurred at a much lower rate at 4 degrees C than at 37 degrees C. The uptake of [(3)H]folic acid was saturable at higher concentrations and inhibited by typical metabolic inhibitors, sodium azide and 2,4-dinitrophenol. The uptake of [(3)H]folic acid was significantly increased with decreasing pH of the incubation buffer and markedly inhibited by 4,4'-diidothiocyanostilbene-2,2'-disulfonic acid (DIDS). Analogs of folic acid, methotrexate and 5-methyltetrahydrofolate, inhibited the uptake of [(3)H]folic acid by BeWo cells. Kinetic analysis using Lineweaver-Burk plots revealed that methotrexate competitively inhibited the uptake of [(3)H]folic acid and folic acid competitively inhibited the uptake of [(3)H]methotrexate. In transport experiments, the permeation of [(3)H]folic acid from the apical-to-basal side was greater than that from the basal-to-apical side, and the transport of [(3)H]folic acid from the apical-to-basal side was inhibited by an excess of folic acid. The findings obtained in the present study confirm the existence of an asymmetric, carrier-mediated transport system for folic acid and its analog, methotrexate, across BeWo cells, a representative of the human trophoblast.
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Affiliation(s)
- T Takahashi
- Department of Pharmaceutics and Biopharmaceutics, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
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25
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Abstract
Paracellular pathways in the haemotrichorial placenta of the rat were studied by electron microscopy using lanthanum hydroxide as an electron dense marker. Near term placentae were dually perfused in situ, adding lanthanum to the fetal perfusate. In some placentae outflow pressure on the fetal side was elevated (between 10 and 25 cm H(2)O) to promote filtration of fluid in a fetomaternal direction. Under normal pressure conditions lanthanum particles lined the subendothelial spaces and tubular structures in the inner, syncytial layer of trophoblast. Further penetration of lanthanum into the tubules was blocked by coarse lanthanum aggregates. Elevated fetal hydrostatic pressure resulted in a fluid shift across the placenta (filtration rate 50+/-16 per cent of fetal arterial inflow rate), distending the tubules in the inner trophoblast layer. Lanthanum particles gradually appeared in tubular structures in the middle (syncytial) layer and in the lateral intercellular spaces in the outer (cellular) layer. Finally lanthanum reached the maternal surface of the trophoblast. These pressure effects were only partially reversible. When the fetal pressure was returned to control values, some distension of the tubules persisted and the entire length of the paracellular pathways remained accessible to lanthanum. It is concluded that the placental barrier in the rat contains pressure dependent paracellular pathways connecting the maternal and fetal extracellular compartments.
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Affiliation(s)
- S Kertschanska
- Department of Anatomy II, University of Technology Aachen, Aachen, D-52057, Germany.
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26
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Utoguchi N, Chandorkar GA, Avery M, Audus KL. Functional expression of P-glycoprotein in primary cultures of human cytotrophoblasts and BeWo cells. Reprod Toxicol 2000; 14:217-24. [PMID: 10838122 DOI: 10.1016/s0890-6238(00)00071-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The objective of this study was to investigate the functional expression of the efflux transporter, P-glycoprotein (P-gp), in primary cultures of human cytotrophoblasts and BeWo cell monolayers. Uptake studies with primary cultures of human cytotrophoblasts or BeWo cells were conducted with calcein-AM and vinblastine (P-gp markers) or fluorescein (MRP marker) in the presence of specific P-gp or MRP inhibitors. Results showed that the accumulation of P-gp substrates calcein-AM and vinblastine by BeWo cells or primary cultures of human cytotrophoblasts was significantly enhanced in the presence of a typical P-gp inhibitor, cyclosporin-A, or other inhibitors such as quinidine, verapamil, and dipyridamole. MRP inhibitors had no effect on the accumulation of calcein or fluorescein by BeWo cells. Western blots confirmed the presence of multidrug resistant gene product 1 (MDR1) in both primary cultures of human cytotrophoblasts and BeWo cells. This study demonstrates functional P-gp in term human trophoblasts and further supports the use of primary cultures of human cytotrophoblasts and BeWo cells as in vitro models of the trophoblast to investigate mechanisms regulating drug distribution across the placenta.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP-Binding Cassette Transporters/antagonists & inhibitors
- ATP-Binding Cassette Transporters/metabolism
- Adult
- Blotting, Western
- Choriocarcinoma/metabolism
- Culture Media, Conditioned/chemistry
- Cyclosporine/pharmacology
- Dipyridamole/pharmacology
- Drug Resistance, Multiple
- Female
- Fluoresceins/metabolism
- Fluorescent Dyes/metabolism
- Humans
- Multidrug Resistance-Associated Proteins
- Pregnancy
- Quinidine/pharmacology
- Trophoblasts/drug effects
- Trophoblasts/metabolism
- Tumor Cells, Cultured
- Verapamil/antagonists & inhibitors
- Vinblastine/pharmacology
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Affiliation(s)
- N Utoguchi
- Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, KS 66047, USA
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27
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Brownbill P, Mahendran D, Owen D, Swanson P, Thornburg KL, Nelson DM, Sibley CP. Denudations as paracellular routes for alphafetoprotein and creatinine across the human syncytiotrophoblast. Am J Physiol Regul Integr Comp Physiol 2000; 278:R677-83. [PMID: 10712288 DOI: 10.1152/ajpregu.2000.278.3.r677] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested two hypotheses: 1) that fibrin-containing fibrinoid-filled denudations of the syncytiotrophoblast may provide a route for paracellular diffusion and 2) that placentas from women who had elevated maternal serum alphafetoprotein (MSAFP) in midgestation had raised permeability to AFP and greater denudation than in normal pregnancy. We measured AFP and creatinine clearance across term placental cotyledons from the above groups and used light microscope morphometric analysis to determine the volume density of fibrin-containing fibrinoid deposits. There was no significant difference between the two groups in terms of AFP and creatinine clearance or volume density of fibrin-containing fibrinoid deposits. The combined data showed a significant (P < 0.05) positive correlation between creatinine clearance, but not AFP clearance, and volume density of fibrin-containing fibrinoid. We conclude that syncytiotrophoblast denudations, with associated fibrinoid, do provide a route for diffusion of small hydrophilic solutes, but that other anatomic features of the placenta are rate limiting for transfer of AFP and similarly sized molecules.
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Affiliation(s)
- P Brownbill
- Academic Unit, St. Mary's Hospital, Manchester, M13 0JH United Kingdom
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28
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Utoguchi N, Magnusson M, Audus KL. Carrier-mediated transport of monocarboxylic acids in BeWo cell monolayers as a model of the human trophoblast. J Pharm Sci 1999; 88:1288-92. [PMID: 10585224 DOI: 10.1021/js990173q] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The monolayer-forming, human choriocarcinoma cell line, BeWo, was used to study the mechanisms of monocarboxylic acid transport across the human trophoblast. Benzoic acid, acetic acid, and lactic acid were used as markers for monocarboxylic acid carrier-mediated transport. The uptake of benzoic acid by BeWo cells was saturable (K(t) = 0.6 +/- 0.3 mM) at higher concentrations and significantly inhibited by typical metabolic inhibitors, sodium azide and 2, 4-dinitrophenol. A selection of different monocarboxylic acids, including a natural substrate lactic acid, also substantially inhibited the uptake of benzoic acid and acetic acid by BeWo cells, whereas dicarboxylic acids did not affect the uptake of either marker. Monocarboxylic acid uptake was pH-dependent and inhibited by carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), a protonophore. Kinetic analysis using Lineweaver-Burk plots revealed that monocarboxylic acids competitively inhibited the uptake of benzoic, lactic, and acetic acid by BeWo cells. In transport experiments, the permeation of benzoic acid from apical-to-basolateral side was greater than the permeation from the basolateral-to-apical side, and the transport of benzoic acid from apical-to-basolateral side was inhibited by monocarboxylic acids. The findings obtained in the present study confirm the existence of an asymmetric, carrier-mediated transport system for monocarboxylic acids across the BeWo cell, a representative of the human trophoblast.
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Affiliation(s)
- N Utoguchi
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66047, USA
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29
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Abstract
Pregnancy in the 20th century involves women of many age groups from early teens to the fourth or fifth decade. Modern medicine and in vitro fertilization techniques have increased options for pregnancy and childbirth. Pregnancy is a dynamic state, and medical concerns may involve disorders of the fetus and mother requiring medications and special nutrients. Therefore, different techniques have been developed to evaluate the placental transfer of drugs and nutrients using tissues and cells derived from human placenta. These include (a) isolated tissues and cells to study placental transport, (b) primary and malignant trophoblast cell cultures and (c) biophysical methods for studying placental transport. Also, convenient study models have been developed to evaluate placental transfer of safe drugs in pregnant women. Some of the drugs studied by these techniques and models include (a) anesthetics and pain medications used during delivery, (b) antibiotics and anti-bacterials used to cure infections, (c) drugs abused by pregnant women and (d) nutrients required for proper fetal growth. Placental transfer and exchange mechanisms are complicated processes, and in vitro models reflect only partially the equilibria that exist among mother, placenta and fetus. The perfused cotyledon model is elegant and simple but gives only restricted information. Isolated placental tissues give useful information about the pharmacological effects of drugs. Metabolic studies using human placental models provide information on the metabolism of a drug during placental transfer and accumulation of the drug or its metabolite in the placenta or fetal circulation. Several studies on the transplacental passage of drugs exist but many questions regarding the transfer of drugs between the maternal and fetal circulations and clearance of drugs from fetal circulation have yet to be answered. This article reviews in vitro and in vivo methods for evaluation of transplacental transport of drugs and their current effectiveness to obtain clinically useful data.
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Affiliation(s)
- BV Sastry
- Professor of Pharmacology, Emeritus, Adjunct Professor of Anesthesiology, Vanderbilt Medical Center, Nashville, TN, USA
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30
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31
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Abstract
Angiotensin converting enzyme (ACE) and leucine aminopeptidase (LAP) regulate fetally and maternally generated peptides in the placenta. In this study, ACE-like activity was found to be decreased and LAP-like activity increased with increasing days of gestation in rat placental tissues forming the fetal:maternal interface. Membrane-associated ACE-like and LAP-like activities in the placenta of smokers were also found to be significantly higher than their respective activities in placenta of nonsmokers. Our collective findings suggest that gestational and environmentally-induced changes in placental peptidase activities may account for variable peptide hormone and/or therapeutic peptide metabolism in the placenta.
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Affiliation(s)
- J Kenagy
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence 66047, USA
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32
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Liu F, Soares MJ, Audus KL. Permeability properties of monolayers of the human trophoblast cell line BeWo. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:C1596-604. [PMID: 9374645 DOI: 10.1152/ajpcell.1997.273.5.c1596] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The BeWo cell line (b30 clone) has been examined as a potential in vitro system to study transplacental transport. At the light and electron microscope level, the cells were observed to form confluent monolayers on polycarbonate filters in approximately 5 days and morphologically resembled the typical human trophoblast. BeWo monolayers developed a modest transepithelial electrical resistance and a molecular size-dependent permeability to hydrophilic passive diffusion markers, fluorescein, and selected fluorescein-labeled dextrans. Linoleic acid permeation across BeWo monolayers was asymmetric, saturable, and inhibited by low temperature and excess competing fatty acid. Forskolin and 8-bromoadenosine 3',5'-cyclic monophosphate treatments stimulated morphological changes in BeWo cultures and enhanced the asymmetric passage of linoleic acid across the BeWo monolayers while having minimal effects on passive permeability, affirming that the differentiation state of the cells can influence membrane transporters and transmonolayer permeability. The basic permeability properties of the BeWo monolayers suggest that the cells grown on permeable supports may be examined as a convenient in vitro system to evaluate some transplacental transport mechanisms.
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Affiliation(s)
- F Liu
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence 66045, USA
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33
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Nelson DM, Swanson PE, Davison BB, Baskin GB, Enders AC. Ontogenetic and phylogenetic evaluation of the presence of fibrin-type fibrinoid in the villous haemochorial placenta. Placenta 1997; 18:605-8. [PMID: 9290158 DOI: 10.1016/0143-4004(77)90017-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The hypothesis that fibrin type fibrinoid deposition on villi is unique to the term human placenta was tested. Bright-field microscopy was used to examine sections of first and second trimester human placental villi and tissues from three animal species that have villous haemochorial placentae similar to the human: the armadillo, the baboon and the rhesus. Sections stained with haematoxylin and eosin showed fibrin type fibrinoid deposits were hypocellular, eosinophilic masses attached to the surface of villi examined from both the human and the animal species. The deposits were located at discontinuities in the syncytiotrophoblast layer, and the fibrinoid provided a matrix for trophoblast re-epithelization of the villous surface. It is concluded that fibrin-type fibrinoid is not unique to the term human placenta. The presence of the syncytiotrophoblast discontinuities associated with the fibrinoid deposition must be considered in models of maternal-fetal exchange in the villous haemochorial placenta.
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Affiliation(s)
- D M Nelson
- Department of Obstetrics and Gynaecology, Washington University School of Medicine, St Louis, Missouri, USA.
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34
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Shi F, Soares MJ, Avery M, Liu F, Zhang X, Audus KL. Permeability and metabolic properties of a trophoblast cell line (HRP-1) derived from normal rat placenta. Exp Cell Res 1997; 234:147-55. [PMID: 9223380 DOI: 10.1006/excr.1997.3603] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The HRP-1 cell line is derived from normal rat placenta and appears morphologically similar to and retains characteristic expression of cellular markers of labyrinthine trophoblast cells. In this study, monolayers of HRP-1 cells grown on permeable supports were evaluated as a potential in vitro system to study trophoblast transport and metabolism. The cell line was shown to express and retain functional activity of the predominant placental cytochrome P450 isozyme, CYP1A1. Additionally, the HRP-1 cells retain functional activity of angiotensin I converting enzyme and carboxypeptidase N-like enzyme, peptidases characteristic of the trophoblast. The permeation of several hydrophilic, inert markers across the HRP-1 monolayers was observed to be dependent on effective molecular size and to be passive in nature. Functional asymmetry of the HRP-1 cells was illustrated by the predominant permeation of linoleic acid in the apical-to-basolateral direction across the monolayers. Transferrin passage across HRP-1 monolayers was concentration-dependent, was bidirectional, and could be inhibited by unlabeled transferrin, features typical of the trophoblast transport system for transferrin. Collectively, these properties suggest that the HRP-1 cell line may provide a useful tool for evaluating some of the permeability and metabolic properties of the trophoblast.
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Affiliation(s)
- F Shi
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence 66047, USA
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35
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Abstract
Endothelial paracellular junctions are important structures for the regulation of vascular permeability, junctional organisation being systematically related to the functional properties of the endothelium. Electron microscopic studies, immunocytochemistry, and single-passage permeability measurements have established that the placental microvessels resemble the fairly tight continuous microvessels of skeletal muscle both in structure and permeability. The endothelial paracellular clefts of these microvessels contain two distinct junctional entities which may influence permeability: the tight junction and the adherens junction. These clefts impose a substantial restriction to molecules above RMM 1000 Da and large haemproteins cannot cross the clefts. The 18 nm-wide zones of the clefts possess the transmembrane adhesion molecules PECAM-1 and VE-cadherin, which have been implicated in junctional assembly and permeability. Inflammatory mediators such as histamine and tumour necrosis factor cause a redistribution of these adhesion molecules to non-junctional regions, and histamine (100 microM) causes a rapid and sustained rise in extraction of radio-labeled tracers. Electron microscopy has also revealed possible first indications of tight junctional disassembly. Both the endothelia of larger placental vessels and isolated placental microvascular endothelial cells express cadherins and PECAM-1 and contain an extensive F-actin cytoskeleton, which is implicated in changes of cell shape and junctional assembly/disassembly. Thus, the human placental endothelium, using perfusion techniques and in vitro experiments, offers a valuable model for vascular permeability studies.
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Affiliation(s)
- L Leach
- Department of Human Anatomy & Cell Biology, Medical School, University of Nottingham, Queens Medical Centre, United Kingdom
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36
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Kertschanska S, Kosanke G, Kaufmann P. Pressure dependence of so-called transtrophoblastic channels during fetal perfusion of human placental villi. Microsc Res Tech 1997; 38:52-62. [PMID: 9260837 DOI: 10.1002/(sici)1097-0029(19970701/15)38:1/2<52::aid-jemt7>3.0.co;2-w] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
To test the influence of perfusion pressures on structural preservation of human placental villi and on the dilatation of the so-called transtrophoblastic channels, cotyledons of 32 term human placentas have been perfused in vitro. Periods of perfusion with isotonic Ringer solution under various arterial and venous hydrostatic pressures were followed by perfusion fixation. In some experiments, lanthanum hydroxide as an extracellular marker was added to the fixative. Distention of the fetal vascular system, stromal edema and continuity, as well as trophoblastic vacuolization were studied via electron microscopy with subsequent morphometry. The findings suggest that arterial hydrostatic pressures in the perfusion system of about 80 cm H2O are needed to guarantee homogeneous perfusion of the fetal vascular system. To avoid stromal edema and trophoblastic vacuolization, venous hydrostatic pressures of 4 cm H2O and arterial hydrostatic pressures of 80 cm H2O should not be exceeded. It is concluded that the trophoblastic vacuoles are dilated segments of the so-called transtrophoblastic channels. The functional importance of in vivo variations of fetal intravascular hydrostatic pressure for the dilatation of transtrophoblastic channels and for fetal water balance is discussed.
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37
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Abstract
The occurrence of acetylcholine (ACh)-like activity in human placenta, a tissue without innervation, has been known for more than 60 years. However, the non-neuronal functions of ACh in human placenta are not clearly understood. The components of the cholinergic system-ACh, choline acetyltransferase, acetylcholinesterase, butyrylcholinesterase, muscarinic receptors, and nicotinic receptors--in human placenta have been demonstrated by unequivocal methods. Primate placentae store and release ACh by mechanisms similar to those of nervous tissue. However, there are many gaps in our knowledge, which include: (a) endogenous quaternary ammonium compounds other than ACh in human placental extracts; (b) the specificity of placental enzymes; (c) the subtypes and structures of placental muscarinic and nicotinic receptors; and (d) the significance of placental alpha-bungarotoxin binding proteins, ACh receptor stimulation-cellular signaling by second messengers, and activation of immediate early target genes (C-fos, C-jun) encoding transcription factors. Several hypothetical non-neuronal functions of ACh in placenta have been postulated based upon available experimental evidence. These include: (a) regulation of blood flow and fluid volume in placental vessels; (b) opening and closing of trophoblastic channels; (c) induction of contractile properties to myofibroblasts; (d) facilitation of amino acid transport necessary for fetal growth across placenta; (e) release of placental hormones; and (f) modulation of the formation of myometrial and placental prostaglandins in human parturition. All of these roles are reasonable, and some of these roles mav turn out to be linked to one another to influence or maintain placental function.
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Affiliation(s)
- B V Sastry
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232-2125, USA
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38
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Kertschanska S, Schröder H, Kaufmann P. The ultrastructure of the trophoblastic layer of the degu (Octodon degus) placenta: a re-evaluation of the 'channel problem'. Placenta 1997; 18:219-25. [PMID: 9089785 DOI: 10.1016/s0143-4004(97)90096-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Previous studies on immersion-fixed specimens of the haemomonochorial labyrinthine chorioallantoic placenta of the degu have made visible channels or pores which completely crossed the trophoblastic layer; for the first time hints for an open connection between maternal blood spaces and fetal interstitium were demonstrated in a placenta. This important finding was re-evaluated by means of transmission electron microscopy paying particular attention to the influence of the mode of fixation and of ischaemic periods prior to fixation. Thirty placentae from seven near-term degu (estimated gestational age 80-90 days) were fixed at various times (5-45 min) after maternal death. Placentae were perfused in situ via the aorta/uterine arteries or the umbilical vein with 2.2 per cent phosphate-buffered glutaraldehyde (n = 7, ischaemic periods < 5-45 min) or lanthanum hydroxide/osmium tetroxide (n = 7, ischaemic periods < 5 min), or were immersion-fixed in 2.2 per cent phosphate-buffered glutaraldehyde (n = 16, ischaemic periods 10-45 min). In material with brief ischaemic periods (n = 3, 5-10 min) no open connections between the maternal blood lacunae and fetal interstitium could be detected. Instead, occasional foci of trophoblast reduced to a thickness of 0.1 micron were found. After ischaemic periods exceeding 10 min, the thin trophoblastic diaphragms had partly disappeared resulting in complete transtrophoblastic pores. It is likely, therefore, that visible trophoblastic pores or channels in the degu placenta are ischaemic artefacts. Application of lanthanum hydroxide from the fetal circulation showed that a branching system of membrane-lined tubules (15-50 nm wide) intruded the trophoblast from its basal side, as has been reported for the guinea-pig and human placenta. It remains to be investigated whether these invaginations belong to a continuous transtrophoblastic channel system.
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39
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Firth JA, Leach L. Structure and permeability in human placental capillaries. Placenta 1997. [DOI: 10.1016/s0143-4004(97)80090-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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40
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Some gestational changes in placental transfer of ions. Placenta 1997. [DOI: 10.1016/s0143-4004(05)80162-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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41
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Firth JA, Leach L. Not trophoblast alone: a review of the contribution of the fetal microvasculature to transplacental exchange. Placenta 1996; 17:89-96. [PMID: 8730878 DOI: 10.1016/s0143-4004(96)80001-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The fetal microcirculation of the term human placenta offers an interesting microvascular model. A perfused placenta can be used for integrated studies of vascular permeability-structure relationships. The organization of the paracellular pathway in human placental microvessels closely resembles not only that of the guinea-pig placenta, but also that seen in typical continuous non-cerebral capillaries such as those of the myocardium. This uniformity of organization has allowed the development of a model of the organization of endothelial junctional complexes that allows testable predictions about the relationship between junctional organization and microvascular permeability. The key features of this model are: (1) molecular size restriction may be determined by a fibre matrix based on cadherin arrays in the zonula adhaerens. (2) The zonula occludens (tight junction) is discontinuous and so cannot act as a molecular sieve for solutes. It may serve as a shutter that limits the proportion of the paracellular cleft available for permeation. The main implication for placental function is that the human placental microcirculation is relatively tight and is an important restriction to diffusive permeation of the maternal-fetal barrier by large molecules.
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Affiliation(s)
- J A Firth
- Imperial College School of Medicine at St. Mary's, Department of Anatomy and Cell Biology, St. Mary's Hospital Medical Centre, London, UK
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42
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Malek A, Ivy D, Blann E, Mattison DR. Impact of cocaine on human placental function using an in vitro perfusion system. J Pharmacol Toxicol Methods 1995; 33:213-9. [PMID: 8527829 DOI: 10.1016/1056-8719(95)00018-d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The transport of cocaine from the maternal to fetal circulation and the effect of cocaine on placental function was investigated in vitro using dually perfused term human placentae with recirculation of both maternal and fetal perfusates. In the first experimental group (n = 5, 2 hr), after addition of 3H-cocaine and 14C-inulin to the maternal circulation, steady state concentrations were achieved within 20 min on the maternal side. However, in the following 100 min, uptake of 3H-cocaine remained higher than of the 14C-inulin on the maternal side. 3H-Cocaine was transported more rapidly than 14C-inulin into the fetal circulation and was detected within 10-15 min of initiation of perfusion. In the second experimental group (n = 6), the maternofetal permeability of 14C-insulin was determined in the same placental perfusion in both the absence (control period, 2 hr) and presence of cocaine (test phase, 2 hr) with its 3H-tracer. After the addition of cocaine (2-3 mg/L), the transfer of 14C-inulin was reduced from 6.59 to 3.64 mL/gm per min (p < .001), indicating that cocaine alters placental permeability. In addition to its effect on placental permeability, cocaine decreases the rate of release of hCG into the maternal circulation--reduced from 3.11 (control period) to 1.62 IU/min (test phase, p < .01).
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Affiliation(s)
- A Malek
- Department of Obstetrics and Gynecology, University of Arkansas for Medical Sciences, Little Rock, USA
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43
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Abstract
Normal fetal growth and development depend on a continuous supply of amino acids from the mother to the fetus. The placenta is responsible for the transfer of amino acids between the two circulations. The human placenta is hemomonochorial, meaning that the maternal and fetal circulations are separated by a single layer of polarized epithelium called the syncytiotrophoblast, which is in direct contact with maternal blood. Transport proteins located in the microvillous and basal membranes of the syncytiotrophoblast are the principal mechanism for transfer from maternal blood to fetal blood. Knowledge of the function and regulation of syncytiotrophoblast amino acid transporters is of great importance in understanding the mechanism of placental transport and potentially improving fetal and newborn outcomes. The development of methods for the isolation of microvillous and basal membrane vesicles from human placenta over the past two decades has contributed greatly to this understanding. Now a primary cultured trophoblast model is available to study amino acid transport and regulation as the cells differentiate. The types of amino acid transporters and their distribution between the syncytiotrophoblast microvillous and basal membranes are somewhat unique compared with other polarized epithelia. These differences may reflect the unusual circumstance of this epithelium that is exposed to blood on both sides. The current state of knowledge as to the types of transport systems present in syncytiotrophoblast, their regulation, and the effects of maternal consumption of drugs on transport are discussed.
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Affiliation(s)
- A J Moe
- Edward Mallinkrodt Department of Pediatrics, Children's Hospital, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Scherer R, Holzgreve W. Influence of epidural analgesia on fetal and neonatal well-being. Eur J Obstet Gynecol Reprod Biol 1995; 59 Suppl:S17-29. [PMID: 7556818 DOI: 10.1016/0028-2243(95)93909-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Epidural analgesia is a frequently used method to reduce the pain of child-bearing. Concerns regarding the safety and potential hazards still persist in the medical community. This review intends to examine how epidural analgesia determines the various factors of fetal and neonatal well-being. Placental drug transfer of opiates like morphine, pethidine and fentanyl is rapid and can lead to neonatal depression. Sufentanil seems to be the safest opiate to administer epidurally. Local anaesthetics are transferred to the fetus in substantial amounts, but the reported effects are subtle and are probably inconsequential. Utero- and fetoplacental blood flow seems to be improved by epidural analgesia with local anaesthetics. Even when using stronger solutions for more extensive blockade in patients for caesarean section, no adverse effects could be demonstrated using pulsed Doppler technique as long as prolonged hypotension (> 2 min) is avoided. Hypotension is best prevented with 20-25 ml/kg crystalloid preload and prompt treatment with ephedrine or etilephrine. Addition of adrenaline to local anaesthetics is considered to be safe for the healthy mother and fetus but it should best be avoided in mothers with pregnancy induced hypertension. Fetal and neonatal acid-base balance and gas-exchange are not adversely affected by epidural analgesia. Many studies show that epidural analgesia can indeed protect the fetus if hypotension is prevented. Neonatal well-being evaluated by APGAR, BRAZELTON, SCANLON and NACS scores is not significantly influenced by local anaesthetics. Neonatal depression can occur however with epidural use of morphine, fentanyl and alfentanil. Sufentanil, again in doses up to 30 micrograms in association with bupivacaine seems to be devoid of depressive effects on the neonate. In summary, the anaesthetist has good arguments to reassure his obstetrical colleagues that providing epidural analgesia for pregnant women in labour is a justifiable intervention to support the natural process of child-bearing.
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Affiliation(s)
- R Scherer
- Chefarzt der Klinik für Anästhesiologie und operative Intensivmedizin, Clemenshospital GmbH, Münster, Germany
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Abstract
The transport of large amounts of Ca2+ by the plasma membranes of human placental syncytiotrophoblast is essential to the mineralization of the growing fetal skeleton. We have investigated transport by the basal (fetal-facing) plasma membrane (BPM). Ca2+ was taken up by purified BPM vesicles in a time-dependent manner and equilibrium attained in approximately 60 min. The apparent equilibrium space was many fold higher than that determined using other substrates (e.g. leucine), suggesting that Ca2+ is concentrated or bound within the vesicles. The more rapid uptake and exit in the presence of A23187 indicates that membrane transport is rate limiting and that Ca2+ is internalized within the membrane space. The initial rate of uptake was approximately by measurement during the first 2 s of incubation. Concentration dependence data were fit to a Michaelis-Menten model with one saturable site and diffusion (Km = 12 microM; Vmax = 4 nmol/min/mg; KD = 39 nmol/min/mg/mM). Saturable Ca2+ binding (Kd = 16 microM; Bmax = 3.4 nmol/mg) was of lower capacity than previously observed for microvillous membrane.
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Affiliation(s)
- S G Kamath
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St Louis Children's Hospital, Missouri 63110
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Affiliation(s)
- G Desoye
- Department of Obstetrics and Gynecology, University of Graz, Austria
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Stulc J, Stulcová B, Sibley CP. Evidence for active maternal-fetal transport of Na+ across the placenta of the anaesthetized rat. J Physiol 1993; 470:637-49. [PMID: 8308747 PMCID: PMC1143938 DOI: 10.1113/jphysiol.1993.sp019879] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
1. In order to investigate mechanisms of Na+ transfer, the unidirectional maternal-fetal clearance (Kmf) of 22Na+ and of 51Cr-EDTA (a marker of paracellular diffusion) was measured across the intact or umbilically or dually perfused placenta of the anaesthetized rat. 2. The Kmf of 22Na+ in the intact preparation (18.5 +/- 2.7 microliters min-1, mean +/- S.D., n = 105 placentas) exceeded that of 51Cr-EDTA in the same experiments (1.4 +/- 0.3 microliters min-1) by more than ten times, whereas the difference in their diffusion coefficients in water was only 2-fold. In the perfused preparations the difference in the Kmf values was 6-fold. 3. Assuming that a simple model of paracellular diffusion through wide pores was one component of transfer, the Kmf of 51Cr-EDTA and the diffusion coefficients were used to calculate a component of 22Na+ clearance (Kmf,residual) and of Na+ flux (Jmf,residual) across the perfused placentas which could not be accounted for by transfer through the paracellular route. 4. Kmf,residual of 22Na+ across the dually perfused placenta was significantly lower when temperature was reduced, the temperature quotient (Q10) of the transfer being about 2. Kmf,residual was also significantly lower when 0.1 mM ouabain was perfused on the fetal side. Jmf,residual exhibited saturation kinetics characterized by an apparent Michaelis constant (Km) of 90 mM. Kmf,residual was not influenced by 0.5 mM frusemide, 0.5 mM amiloride or by 0.5 mM hydrochlorothiazide administered to the maternal side. It was significantly increased by 1 mM alanine on the maternal side suggesting that the coupled transfer of Na+ and amino acids may contribute significantly to the maternal-fetal flux of Na+. 5. These observations suggest that most (80%) of the maternal-fetal flux of Na+ across the rat placenta is effected by active transcellular transport. This transport involves passive entry of Na+ into the trophoblast from the maternal side by a largely unknown saturable mechanism and active extrusion of Na+ from trophoblast to the fetal side by Na(+)-K(+)-ATPase.
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Affiliation(s)
- J Stulc
- Department of Pharmacology, 2nd Faculty of Medicine, Charles University, Prague, Czech Republic
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Jansson T, Powell TL, Illsley NP. Non-electrolyte solute permeabilities of human placental microvillous and basal membranes. J Physiol 1993; 468:261-74. [PMID: 8254509 PMCID: PMC1143825 DOI: 10.1113/jphysiol.1993.sp019770] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
1. Permeability to non-electrolytes of isolated microvillous and basal membranes from human term placenta was measured using stopped-flow light-scattering techniques. The studied solutes were urea, ethylene glycol, glycerol, creatinine, erythritol, arabitol and mannitol. 2. At 37 degrees C, permeability of the microvillous membrane to mannitol and urea was 0.30 +/- 0.02 x 10(-6) cm/s (mean +/- S.E.M.) and 3.2 +/- 0.2 x 10(-6) cm/s, respectively. The corresponding permeabilities for the basal membrane were 1.2 +/- 0.1 x 10(-6) cm/s (mannitol) and 4.4 +/- 0.3 x 10(-6) cm/s (urea). The basal membrane was substantially more permeable to hydrophilic solutes than the microvillous membrane. This is probably due to differences in lipid composition, as illustrated by membrane cholesterol content, which was found to be approximately 50% lower in the basal as compared to the microvillous membrane. 3. Similarities between permeabilities in placental membranes and lipid bilayers and the linear relationship noted between solute hydrophobicity and placental permeability suggested that solutes permeate both human syncytiotrophoblast membranes by a solubility/diffusion mechanism. In the microvillous membrane this was supported by data obtained for activation energies (> 10 kcal/mol) and reflection coefficients (close to 1). In the basal membrane, low activation energies for glycerol and urea and a low reflection coefficient for urea indicated that these solutes may, in part, share a common pathway with water. 4. It was estimated that the placental permeability to molecules with a molecular weight under 200 observed in vivo can, to a great extent, be accounted for by transcellular permeation.
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Affiliation(s)
- T Jansson
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco 94143
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Greenwood SL, Boyd RD, Sibley CP. Transtrophoblast and microvillus membrane potential difference in mature intermediate human placental villi. THE AMERICAN JOURNAL OF PHYSIOLOGY 1993; 265:C460-6. [PMID: 8368275 DOI: 10.1152/ajpcell.1993.265.2.c460] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Single mature intermediate villi from term placentas after normal gestation and vaginal or cesarian delivery were identified microscopically and mounted in a bath for conventional micro-electrode studies. With the application of strict selection criteria, the following observations on electrical potential difference (PD) were made. 1) With the tissue bathed in Earle's medium (37 degrees C) the PD across the syncytiotrophoblast microvillus membrane with respect to the bath was not normally distributed. The median PD was -22 mV (range -12 to -60 mV, n = 200). This fell to -6 mV after prior incubation for 4 h with cyanide (3 mM) or iodoacetate (2 mM) but was not altered by short-term application of these agents or by 0.1 mM ouabain. Substituting Na+ in Earle's medium with choline had no effect on PD, but replacing Cl- with gluconate caused a depolarization of 6 mV (P < 0.002). Increasing KCl in the bath fluid revealed an apparently low microvillus membrane K+ conductance. The low microvillus membrane PD may reflect a low Na(+)-K(+)-ATPase activity and/or a low membrane permeability to K+. 2) The transtrophoblast PD measured by insertion and withdrawal of the electrode was significantly different from zero [P < 0.003, median -3 mV (range 0 to -15 mV), n = 11]; and PD measured by insertion of the electrode into the villus core and beyond was -6 mV (significantly different from zero P < 0.003, range -2.5 to -10 mV, n = 6). If a similar PD were to exist in vivo, it could have a significant influence on ion transport across the placenta at term.
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Affiliation(s)
- S L Greenwood
- Department of Child Health, University of Manchester, St. Mary's Hospital, United Kingdom
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