1
|
Lewis RM. Volume electron microscopy reveals placental ultrastructure in 3D. Placenta 2023; 141:78-83. [PMID: 37487796 DOI: 10.1016/j.placenta.2023.07.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 07/26/2023]
Abstract
Many structures necessary for placental function can only be visualised at the ultrastructural scale. Recent technological advances have made Volume electron microscopy (volume EM) approaches much more accessible. Volume EM allows the ultrastructure of tissues, cells and organelles to be visualised in 3D. It also allows the 3D spatial relationships between these structures to be determined. This review will highlight the potential for volume EM to advance our understanding of placental ultrastructure. It will focus on the human term placenta highlighting key findings spanning the placental barrier from trans-syncytial nanopores in the syncytiotrophoblast to tunnelling nanotubes in the fetal capillary endothelium. Volume EM is advancing our understanding of placental ultrastructure, but to fully exploit its potential, it will be necessary to use it as part of multimodal and correlative workflows. The complementary strengths of these different approaches can complement volume EM and reveal the biological significance of its novel observations. The use of volume EM also highlighted how ultrastructural features might underpin pregnancy pathologies and demonstrates the need for more research in this underrepresented area.
Collapse
|
2
|
Clark A, Flouri D, Mufti N, James J, Clements E, Aughwane R, Aertsen M, David A, Melbourne A. Developments in functional imaging of the placenta. Br J Radiol 2023; 96:20211010. [PMID: 35234516 PMCID: PMC10321248 DOI: 10.1259/bjr.20211010] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 01/26/2022] [Accepted: 02/22/2022] [Indexed: 12/21/2022] Open
Abstract
The placenta is both the literal and metaphorical black box of pregnancy. Measurement of the function of the placenta has the potential to enhance our understanding of this enigmatic organ and serve to support obstetric decision making. Advanced imaging techniques are key to support these measurements. This review summarises emerging imaging technology being used to measure the function of the placenta and new developments in the computational analysis of these data. We address three important examples where functional imaging is supporting our understanding of these conditions: fetal growth restriction, placenta accreta, and twin-twin transfusion syndrome.
Collapse
Affiliation(s)
- Alys Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | | | | | - Joanna James
- Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Eleanor Clements
- School of Biomedical Engineering and Imaging Sciences, King’s College London, London, UK
| | - Rosalind Aughwane
- Elizabeth Garrett Anderson Institute for Women’s Health, University College London, London, UK
| | - Michael Aertsen
- Department of Radiology, University Hospitals KU Leuven, Leuven, Belgium
| | - Anna David
- Elizabeth Garrett Anderson Institute for Women’s Health, University College London, London, UK
| | | |
Collapse
|
3
|
Mekler T, Plitman Mayo R, Weissmann J, Marom G. Impact of tissue porosity and asymmetry on the oxygen uptake of the human placenta: A numerical study. Placenta 2022; 129:15-22. [PMID: 36183458 DOI: 10.1016/j.placenta.2022.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 08/17/2022] [Accepted: 09/14/2022] [Indexed: 12/14/2022]
Abstract
INTRODUCTION This study proposes a computational fluid dynamics model of a human placenta's independent exchange unit (placentome) to assess the effect that the inner villi distribution and decidual veins (DVs) location and number, have on the oxygen uptake. METHODS The internal placentome porosity distribution was altered in symmetric morphology, while asymmetry was introduced by varying the location and number of DVs. The DV asymmetry was introduced by either displacing them circumferentially, thereby changing the angle between them, or by adding DVs in the inlet cross-section. The results were analyzed by the changes in the normalized oxygen mass fraction and the oxygen uptake. RESULTS Oxygenated blood was shown to be delivered deeper into the placentome when the area of non-homogeneous porosity was larger. The largest oxygen uptake was achieved in the asymmetric model with the smallest angle distance between the DVs, where a 10% decrease relative to the farthest case was obtained. Placing DVs adjacent to the spiral artery opening enhanced the drainage of oxygenated blood. DISCUSSION This study demonstrates the importance of the local porosity distribution for the proper perfusion of the intervillous space and proposes a novel approach to improve our understanding of the role of the DVs in placental oxygen uptake.
Collapse
Affiliation(s)
- Tirosh Mekler
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, 6997801, Israel.
| | - Romina Plitman Mayo
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel.
| | - Jonathan Weissmann
- Department of Biomedical Engineering, The Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv, 6997801, Israel.
| | - Gil Marom
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, 6997801, Israel.
| |
Collapse
|
4
|
Costa J, Mackay R, de Aguiar Greca SC, Corti A, Silva E, Karteris E, Ahluwalia A. The Role of the 3Rs for Understanding and Modeling the Human Placenta. J Clin Med 2021; 10:jcm10153444. [PMID: 34362227 PMCID: PMC8347836 DOI: 10.3390/jcm10153444] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/28/2021] [Accepted: 08/02/2021] [Indexed: 12/12/2022] Open
Abstract
Modeling the physiology of the human placenta is still a challenge, despite the great number of scientific advancements made in the field. Animal models cannot fully replicate the structure and function of the human placenta and pose ethical and financial hurdles. In addition, increasingly stricter animal welfare legislation worldwide is incentivizing the use of 3R (reduction, refinement, replacement) practices. What efforts have been made to develop alternative models for the placenta so far? How effective are they? How can we improve them to make them more predictive of human pathophysiology? To address these questions, this review aims at presenting and discussing the current models used to study phenomena at the placenta level: in vivo, ex vivo, in vitro and in silico. We describe the main achievements and opportunities for improvement of each type of model and critically assess their individual and collective impact on the pursuit of predictive studies of the placenta in line with the 3Rs and European legislation.
Collapse
Affiliation(s)
- Joana Costa
- Centro di Ricerca E.Piaggio, University of Pisa, 56126 Pisa, Italy; (J.C.); (A.C.)
| | - Ruth Mackay
- Centre for Genome Engineering and Maintenance, Department of Mechanical and Aerospace Engineering, Brunel University London, Uxbridge UB8 3PH, UK;
| | | | - Alessandro Corti
- Centro di Ricerca E.Piaggio, University of Pisa, 56126 Pisa, Italy; (J.C.); (A.C.)
- Department of Translational Medicine, University of Pisa, 56126 Pisa, Italy
| | - Elisabete Silva
- College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK; (S.-C.d.A.G.); (E.S.); (E.K.)
| | - Emmanouil Karteris
- College of Health, Medicine and Life Sciences, Brunel University London, Uxbridge UB8 3PH, UK; (S.-C.d.A.G.); (E.S.); (E.K.)
| | - Arti Ahluwalia
- Centro di Ricerca E.Piaggio, University of Pisa, 56126 Pisa, Italy; (J.C.); (A.C.)
- Department of Information Engineering, University of Pisa, 56122 Pisa, Italy
- Interuniversity Centro for the Promotion of 3Rs Principles in Teaching and Research (Centro3R), Italy
- Correspondence:
| |
Collapse
|
5
|
Wheeler ML, Oyen ML. Bioengineering Approaches for Placental Research. Ann Biomed Eng 2021; 49:1805-1818. [PMID: 33420547 DOI: 10.1007/s10439-020-02714-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 12/23/2020] [Indexed: 12/11/2022]
Abstract
Research into the human placenta's complex functioning is complicated by a lack of suitable physiological in vivo models. Two complementary approaches have emerged recently to address these gaps in understanding, computational in silico techniques, including multi-scale modeling of placental blood flow and oxygen transport, and cellular in vitro approaches, including organoids, tissue engineering, and organ-on-a-chip models. Following a brief introduction to the placenta's structure and function and its influence on the substantial clinical problem of preterm birth, these different bioengineering approaches are reviewed. The cellular techniques allow for investigation of early first-trimester implantation and placental development, including critical biological processes such as trophoblast invasion and trophoblast fusion, that are otherwise very difficult to study. Similarly, computational models of the placenta and the pregnant pelvis at later-term gestation allow for investigations relevant to complications that occur when the placenta has fully developed. To fully understand clinical conditions associated with the placenta, including those with roots in early processes but that only manifest clinically at full-term, a holistic approach to the study of this fascinating, temporary but critical organ is required.
Collapse
Affiliation(s)
- Mackenzie L Wheeler
- Department of Engineering, East Carolina University, Greenville, NC, 27834, USA
| | - Michelle L Oyen
- Department of Engineering, East Carolina University, Greenville, NC, 27834, USA.
| |
Collapse
|
6
|
Burton GJ, Jauniaux E. Placentation in the Human and Higher Primates. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2021; 234:223-254. [PMID: 34694484 DOI: 10.1007/978-3-030-77360-1_11] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Placentation in humans is precocious and highly invasive compared to other mammals. Implantation is interstitial, with the conceptus becoming completely embedded within the endometrium towards the end of the second week post-fertilization. Villi initially form over the entire surface of the chorionic sac, stimulated by histotrophic secretions from the endometrial glands. The secondary yolk sac never makes contact with the chorion, and a choriovitelline placenta is never established. However, recent morphological and transcriptomic analyses suggest that the yolk sac plays an important role in the uptake of nutrients from the coelomic fluid. Measurements performed in vivo demonstrate that early development takes place in a physiological, low-oxygen environment that protects against teratogenic free radicals and maintains stem cells in a multipotent state. The maternal arterial circulation to the placenta is only fully established around 10-12 weeks of gestation. By then, villi have regressed over the superficial, abembryonic pole, leaving the definitive discoid placenta, which is of the villous, hemochorial type. Remodeling of the maternal spiral arteries is essential to ensure a high-volume but low-velocity inflow into the mature placenta. Extravillous trophoblast cells migrate from anchoring villi and surround the arteries. Their interactions with maternal immune cells release cytokines and proteases that are key to remodeling, and a successful pregnancy.
Collapse
Affiliation(s)
- Graham J Burton
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
| | - Eric Jauniaux
- Faculty of Population Health Sciences, EGA Institute for Women's Health, University College London, London, UK
| |
Collapse
|
7
|
Abstract
Almost 2 billion adults in the world are overweight, and more than half of them are classified as obese, while nearly one-third of children globally experience poor growth and development. Given the vast amount of knowledge that has been gleaned from decades of research on growth and development, a number of questions remain as to why the world is now in the midst of a global epidemic of obesity accompanied by the "double burden of malnutrition," where overweight coexists with underweight and micronutrient deficiencies. This challenge to the human condition can be attributed to nutritional and environmental exposures during pregnancy that may program a fetus to have a higher risk of chronic diseases in adulthood. To explore this concept, frequently called the developmental origins of health and disease (DOHaD), this review considers a host of factors and physiological mechanisms that drive a fetus or child toward a higher risk of obesity, fatty liver disease, hypertension, and/or type 2 diabetes (T2D). To that end, this review explores the epidemiology of DOHaD with discussions focused on adaptations to human energetics, placental development, dysmetabolism, and key environmental exposures that act to promote chronic diseases in adulthood. These areas are complementary and additive in understanding how providing the best conditions for optimal growth can create the best possible conditions for lifelong health. Moreover, understanding both physiological as well as epigenetic and molecular mechanisms for DOHaD is vital to most fully address the global issues of obesity and other chronic diseases.
Collapse
Affiliation(s)
- Daniel J Hoffman
- Department of Nutritional Sciences, Program in International Nutrition, and Center for Childhood Nutrition Research, New Jersey Institute for Food, Nutrition, and Health, Rutgers, the State University of New Jersey, New Brunswick, New Jersey
| | - Theresa L Powell
- Department of Pediatrics and Department of Obstetrics and Gynecology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Emily S Barrett
- Department of Biostatistics and Epidemiology, School of Public Health and Division of Exposure Science and Epidemiology, Rutgers Environmental and Occupational Health Sciences Institute, Rutgers, the State University of New Jersey, New Brunswick, New Jersey
| | - Daniel B Hardy
- Department of Biostatistics and Epidemiology, School of Public Health and Division of Exposure Science and Epidemiology, Rutgers Environmental and Occupational Health Sciences Institute, Rutgers, the State University of New Jersey, New Brunswick, New Jersey
| |
Collapse
|
8
|
Advances in imaging feto-placental vasculature: new tools to elucidate the early life origins of health and disease. J Dev Orig Health Dis 2020; 12:168-178. [PMID: 32746961 DOI: 10.1017/s2040174420000720] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Optimal placental function is critical for fetal development, and therefore a crucial consideration for understanding the developmental origins of health and disease (DOHaD). The structure of the fetal side of the placental vasculature is an important determinant of fetal growth and cardiovascular development. There are several imaging modalities for assessing feto-placental structure including stereology, electron microscopy, confocal microscopy, micro-computed tomography, light-sheet microscopy, ultrasonography and magnetic resonance imaging. In this review, we present current methodologies for imaging feto-placental vasculature morphology ex vivo and in vivo in human and experimental models, their advantages and limitations and how these provide insight into placental function and fetal outcomes. These imaging approaches add important perspective to our understanding of placental biology and have potential to be new tools to elucidate a deeper understanding of DOHaD.
Collapse
|
9
|
Erlich A, Nye GA, Brownbill P, Jensen OE, Chernyavsky IL. Quantifying the impact of tissue metabolism on solute transport in feto-placental microvascular networks. Interface Focus 2019; 9:20190021. [PMID: 31485311 PMCID: PMC6710657 DOI: 10.1098/rsfs.2019.0021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2019] [Indexed: 12/19/2022] Open
Abstract
The primary exchange units in the human placenta are terminal villi, in which fetal capillary networks are surrounded by a thin layer of villous tissue, separating fetal from maternal blood. To understand how the complex spatial structure of villi influences their function, we use an image-based theoretical model to study the effect of tissue metabolism on the transport of solutes from maternal blood into the fetal circulation. For solute that is taken up under first-order kinetics, we show that the transition between flow-limited and diffusion-limited transport depends on two new dimensionless parameters defined in terms of key geometric quantities, with strong solute uptake promoting flow-limited transport conditions. We present a simple algebraic approximation for solute uptake rate as a function of flow conditions, metabolic rate and villous geometry. For oxygen, accounting for nonlinear kinetics using physiological parameter values, our model predicts that villous metabolism does not significantly impact oxygen transfer to fetal blood, although the partitioning of fluxes between the villous tissue and the capillary network depends strongly on the flow regime.
Collapse
Affiliation(s)
- Alexander Erlich
- School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Gareth A. Nye
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
- Chester Medical School, University of Chester, Chester CH1 4AR, UK
| | - Paul Brownbill
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| | - Oliver E. Jensen
- School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Igor L. Chernyavsky
- School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| |
Collapse
|
10
|
Plitman Mayo R, Abbas Y, Charnock-Jones DS, Burton GJ, Marom G. Three-dimensional morphological analysis of placental terminal villi. Interface Focus 2019; 9:20190037. [PMID: 31485319 DOI: 10.1098/rsfs.2019.0037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2019] [Indexed: 11/12/2022] Open
Abstract
Transport of nutrients and waste between the maternal and fetal circulations during pregnancy takes place at the final branches of the placental villous trees. Therefore, and unsurprisingly, pregnancy complications have been related to the maldevelopment of terminal villi. However, a deep analysis of placental villous morphology has been limited by tissue processing and imaging techniques. In this proof-of-principle study, placental lobules were fixed by perfusion and small clumps of villi were stained, sectioned optically and reconstructed. Morphological and network analyses were suggested and demonstrated on samples of normal placentas. The results show that most parameters are almost constant within a placenta but that there exists an inter-individual variation. Network analysis suggests that the feto-placental capillary network has several paths within an individual villus, serving as an efficient transport system. Three-dimensional reconstruction from confocal laser scanning microscopy images is a potent technique able to quantify placental architecture and capture the significant irregularities in vessel diameter and membrane thickness. This approach has the potential to become a powerful tool to further our understanding of the differences in placental structure which may underlie pregnancy complications.
Collapse
Affiliation(s)
| | - Yassen Abbas
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK.,Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - D Stephen Charnock-Jones
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK.,Department of Obstetrics and Gynaecology, University of Cambridge, Cambridge CB2 0SW, UK
| | - Graham J Burton
- Centre for Trophoblast Research (CTR), Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Gil Marom
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv, Israel
| |
Collapse
|
11
|
Tun WM, Yap CH, Saw SN, James JL, Clark AR. Differences in placental capillary shear stress in fetal growth restriction may affect endothelial cell function and vascular network formation. Sci Rep 2019; 9:9876. [PMID: 31285454 PMCID: PMC6614400 DOI: 10.1038/s41598-019-46151-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 06/19/2019] [Indexed: 11/09/2022] Open
Abstract
Fetal growth restriction (FGR) affects 5-10% of pregnancies, leading to clinically significant fetal morbidity and mortality. FGR placentae frequently exhibit poor vascular branching, but the mechanisms driving this are poorly understood. We hypothesize that vascular structural malformation at the organ level alters microvascular shear stress, impairing angiogenesis. A computational model of placental vasculature predicted elevated placental micro-vascular shear stress in FGR placentae (0.2 Pa in severe FGR vs 0.05 Pa in normal placentae). Endothelial cells cultured under predicted FGR shear stresses migrated significantly slower and with greater persistence than in shear stresses predicted in normal placentae. These cell behaviors suggest a dominance of vessel elongation over branching. Taken together, these results suggest (1) poor vascular development increases vessel shear stress, (2) increased shear stress induces cell behaviors that impair capillary branching angiogenesis, and (3) impaired branching angiogenesis continues to drive elevated shear stress, jeopardizing further vascular formation. Inadequate vascular branching early in gestation could kick off this cyclic loop and continue to negatively impact placental angiogenesis throughout gestation.
Collapse
Affiliation(s)
- Win M Tun
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Choon Hwai Yap
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Shier Nee Saw
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Joanna L James
- Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Alys R Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
| |
Collapse
|
12
|
Erlich A, Pearce P, Mayo RP, Jensen OE, Chernyavsky IL. Physical and geometric determinants of transport in fetoplacental microvascular networks. SCIENCE ADVANCES 2019; 5:eaav6326. [PMID: 31001587 PMCID: PMC6469945 DOI: 10.1126/sciadv.aav6326] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/01/2019] [Indexed: 05/14/2023]
Abstract
Across mammalian species, solute exchange takes place in complex microvascular networks. In the human placenta, the primary exchange units are terminal villi that contain disordered networks of fetal capillaries and are surrounded externally by maternal blood. We show how the irregular internal structure of a terminal villus determines its exchange capacity for diverse solutes. Distilling geometric features into three parameters, obtained from image analysis and computational fluid dynamics, we capture archetypal features of the structure-function relationship of terminal villi using a simple algebraic approximation, revealing transitions between flow- and diffusion-limited transport at vessel and network levels. Our theory accommodates countercurrent effects, incorporates nonlinear blood rheology, and offers an efficient method for testing network robustness. Our results show how physical estimates of solute transport, based on carefully defined geometrical statistics, provide a viable method for linking placental structure and function and offer a framework for assessing transport in other microvascular systems.
Collapse
Affiliation(s)
- Alexander Erlich
- School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Philip Pearce
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307, USA
| | - Romina Plitman Mayo
- Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
- Homerton College, University of Cambridge, Cambridge CB2 8PH, UK
| | - Oliver E. Jensen
- School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Igor L. Chernyavsky
- School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
- Maternal and Fetal Health Research Centre, Division of Developmental Biology and Medicine, School of Medical Sciences, University of Manchester, Manchester Academic Health Science Centre, Manchester M13 9PL, UK
| |
Collapse
|
13
|
Jensen OE, Chernyavsky IL. Blood flow and transport in the human placenta. ANNUAL REVIEW OF FLUID MECHANICS 2019; 51:25-47. [PMID: 38410641 PMCID: PMC7615669 DOI: 10.1146/annurev-fluid-010518-040219] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
The placenta is a multi-functional organ that exchanges blood gases and nutrients between a mother and her developing fetus. In humans, fetal blood flows through intricate networks of vessels confined within villous trees, the branches of which are bathed in pools of maternal blood. Fluid mechanics and transport processes play a central role in understanding how these elaborate structures contribute to the function of the placenta, and how their disorganization may lead to disease. Recent advances in imaging and computation have spurred significant advances in simulations of fetal and maternal flows within the placenta, across a range of lengthscales. Models describe jets of maternal blood emerging from spiral arteries into a disordered and deformable porous medium, and solute uptake by fetal blood flowing through elaborate three-dimensional capillary networks. We survey recent developments and emerging challenges in modeling flow and transport in this complex organ.
Collapse
Affiliation(s)
| | - Igor L. Chernyavsky
- School of Mathematics, University of Manchester, UK
- Maternal and Fetal Health Research Centre, Division of Developmental
Biology & Medicine, School of Medical Sciences, Faculty of Biology, Medicine
& Health, University of Manchester, UK
| |
Collapse
|
14
|
Melbourne A, Aughwane R, Sokolska M, Owen D, Kendall G, Flouri D, Bainbridge A, Atkinson D, Deprest J, Vercauteren T, David A, Ourselin S. Separating fetal and maternal placenta circulations using multiparametric MRI. Magn Reson Med 2018; 81:350-361. [PMID: 30239036 PMCID: PMC6282748 DOI: 10.1002/mrm.27406] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/21/2018] [Accepted: 05/24/2018] [Indexed: 12/18/2022]
Abstract
PURPOSE The placenta is a vital organ for the exchange of oxygen, nutrients, and waste products between fetus and mother. The placenta may suffer from several pathologies, which affect this fetal-maternal exchange, thus the flow properties of the placenta are of interest in determining the course of pregnancy. In this work, we propose a new multiparametric model for placental tissue signal in MRI. METHODS We describe a method that separates fetal and maternal flow characteristics of the placenta using a 3-compartment model comprising fast and slowly circulating fluid pools, and a tissue pool is fitted to overlapping multiecho T2 relaxometry and diffusion MRI with low b-values. We implemented the combined model and acquisition on a standard 1.5 Tesla clinical system with acquisition taking less than 20 minutes. RESULTS We apply this combined acquisition in 6 control singleton placentas. Mean myometrial T2 relaxation time was 123.63 (±6.71) ms. Mean T2 relaxation time of maternal blood was 202.17 (±92.98) ms. In the placenta, mean T2 relaxation time of the fetal blood component was 144.89 (±54.42) ms. Mean ratio of maternal to fetal blood volume was 1.16 (±0.6), and mean fetal blood saturation was 72.93 (±20.11)% across all 6 cases. CONCLUSION The novel acquisition in this work allows the measurement of histologically relevant physical parameters, such as the relative proportions of vascular spaces. In the placenta, this may help us to better understand the physiological properties of the tissue in disease.
Collapse
Affiliation(s)
- Andrew Melbourne
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom.,School of Biomedical Engineering and Imaging, Kings College London, London, United Kingdom
| | - Rosalind Aughwane
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom.,Institute for Women's Health, University College Hospital,London, London, United Kingdom
| | | | - David Owen
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom.,School of Biomedical Engineering and Imaging, Kings College London, London, United Kingdom
| | - Giles Kendall
- Institute for Women's Health, University College Hospital,London, London, United Kingdom
| | - Dimitra Flouri
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom.,School of Biomedical Engineering and Imaging, Kings College London, London, United Kingdom
| | - Alan Bainbridge
- Medical Physics, University College Hospital, London, United Kingdom
| | - David Atkinson
- Centre for Medical Imaging, University College London, London, United Kingdom
| | - Jan Deprest
- Institute for Women's Health, University College Hospital,London, London, United Kingdom.,University Hospital KU Leuven, Leuven, Belgium
| | - Tom Vercauteren
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom.,School of Biomedical Engineering and Imaging, Kings College London, London, United Kingdom
| | - Anna David
- Institute for Women's Health, University College Hospital,London, London, United Kingdom.,University Hospital KU Leuven, Leuven, Belgium.,NIHR University College London Hospitals Biomedical Research Centre, London, United Kingdom
| | - Sebastien Ourselin
- Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom.,School of Biomedical Engineering and Imaging, Kings College London, London, United Kingdom
| |
Collapse
|
15
|
Advances in Human Placental Biomechanics. Comput Struct Biotechnol J 2018; 16:298-306. [PMID: 30181841 PMCID: PMC6120428 DOI: 10.1016/j.csbj.2018.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/06/2018] [Accepted: 08/12/2018] [Indexed: 11/21/2022] Open
Abstract
Pregnancy complications are a major clinical concern due to the related maternal and fetal morbidity. Many are caused through defective placentation, but research into placental function is difficult, principally because of the ethical limitations associated with the in-vivo organ and the difficulty of extrapolating animal models. Perfused by two separate circulations, the maternal and fetal bloodstreams, the placenta has a unique structure and performs multiple complex functions. Three-dimensional imaging and computational modelling are becoming popular tools to investigate the morphology and physiology of this organ. These techniques bear the potential for better understanding the aetiology and development of placental pathologies, however, their full potential is yet to be exploited. This review aims to summarize the recent insights into placental structure and function by employing these novel techniques.
Collapse
|
16
|
Burton GJ, Jauniaux E. Development of the Human Placenta and Fetal Heart: Synergic or Independent? Front Physiol 2018; 9:373. [PMID: 29706899 PMCID: PMC5906582 DOI: 10.3389/fphys.2018.00373] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 03/27/2018] [Indexed: 12/03/2022] Open
Abstract
The placenta is the largest fetal organ, and toward the end of pregnancy the umbilical circulation receives at least 40% of the biventricular cardiac output. It is not surprising, therefore, that there are likely to be close haemodynamic links between the development of the placenta and the fetal heart. Development of the placenta is precocious, and in advance of that of the fetus. The placenta undergoes considerable remodeling at the end of the first trimester of pregnancy, and its vasculature is capable of adapting to environmental conditions and to variations in the blood supply received from the mother. There are two components to the placental membranes to consider, the secondary yolk sac and the chorioallantoic placenta. The yolk sac is the first of the extraembryonic membranes to be vascularized, and condensations in the mesenchyme at ~17 days post-conception (p.c.) give rise to endothelial and erythroid precursors. A network of blood vessels is established ~24 days p.c., with the vitelline vein draining through the region of the developing liver into the sinus venosus. Gestational sacs of early pregnancy failures often display aberrant development of the yolk sac, which is likely to be secondary to abnormal fetal development. Vasculogenesis occurs in the villous mesenchyme of the chorioallantoic placenta at a similarly early stage. Nucleated erythrocytes occupy the lumens of the placental capillaries and end-diastolic flow is absent in the umbilical arterial circulation throughout most of the first trimester, indicating a high resistance to blood flow. Resistance begins to fall in the umbilico-placental circulation around 12–14 weeks. During normal early pregnancy the placental capillary network is plastic, and considerable remodeling occurs in response to the local oxygen concentration, and in particular to oxidative stress. In pregnancies complicated by preeclampsia and/or fetal growth restriction, utero-placental malperfusion induces smooth muscle cells surrounding the placental arteries to dedifferentiate and adopt a proliferative phenotype. This change is associated with increased umbilical resistance measured by Doppler ultrasound, and is likely to exert a major effect on the developing heart through the afterload. Thus, both the umbilical and maternal placental circulations may impact on development of the heart.
Collapse
Affiliation(s)
- Graham J Burton
- Department of Physiology, Development and Neuroscience, Centre for Trophoblast Research, University of Cambridge, Cambridge, United Kingdom
| | - Eric Jauniaux
- Faculty of Population Health Sciences, EGA Institute for Women's Health, University College London, London, United Kingdom
| |
Collapse
|
17
|
Mirbod P. Analytical model of the feto-placental vascular system: consideration of placental oxygen transport. ROYAL SOCIETY OPEN SCIENCE 2018; 5:180219. [PMID: 29765697 PMCID: PMC5936962 DOI: 10.1098/rsos.180219] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 03/13/2018] [Indexed: 06/08/2023]
Abstract
The placenta is a transient vascular organ that enables nutrients and blood gases to be exchanged between fetal and maternal circulations. Herein, the structure and oxygen diffusion across the trophoblast membrane between the fetal and maternal red blood cells in the feto-placental vasculature system in both human and mouse placentas are presented together as a functional unit. Previous models have claimed that the most efficient fetal blood flow relies upon structures containing a number of 'conductive' symmetrical branches, offering a path of minimal resistance that maximizes blood flow to the terminal villi, where oxygen diffusion occurs. However, most of these models have disregarded the actual descriptions of the exchange at the level of the intermediate and terminal villi. We are proposing a 'mixed model' whereby both 'conductive' and 'terminal' villi are presumed to be present at the end of single (in human) or multiple (in mouse) pregnancies. We predict an optimal number of 18 and 22 bifurcation levels in the human and the mouse placentas, respectively. Wherever possible, we have compared our model's predictions with experimental results reported in the literature and found close agreement between them.
Collapse
Affiliation(s)
- Parisa Mirbod
- Department of Mechanical and Aeronautical Engineering, Clarkson University, Potsdam, NY, USA
| |
Collapse
|
18
|
Merz G, Schwenk V, Shah R, Salafia C, Necaise P, Joyce M, Villani T, Johnson M, Crider N. Three-dimensional Rendering and Analysis of Immunolabeled, Clarified Human Placental Villous Vascular Networks. J Vis Exp 2018. [PMID: 29658922 DOI: 10.3791/57099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nutrient and gas exchange between mother and fetus occurs at the interface of the maternal intervillous blood and the vast villous capillary network that makes up much of the parenchyma of the human placenta. The distal villous capillary network is the terminus of the fetal blood supply after several generations of branching of vessels extending out from the umbilical cord. This network has a contiguous cellular sheath, the syncytial trophoblast barrier layer, which prevents mixing of fetal blood and the maternal blood in which it is continuously bathed. Insults to the integrity of the placental capillary network, occurring in disorders such as maternal diabetes, hypertension and obesity, have consequences that present serious health risks for the fetus, infant, and adult. To better define the structural effects of these insults, a protocol was developed for this study that captures capillary network structure on the order of 1 - 2 mm3 wherein one can investigate its topological features in its full complexity. To accomplish this, clusters of terminal villi from placenta are dissected, and the trophoblast layer and the capillary endothelia are immunolabeled. These samples are then clarified with a new tissue clearing process which makes it possible to acquire confocal image stacks to z- depths of ~1 mm. The three-dimensional renderings of these stacks are then processed and analyzed to generate basic capillary network measures such as volume, number of capillary branches, and capillary branch end points, as validation of the suitability of this approach for capillary network characterization.
Collapse
Affiliation(s)
- George Merz
- The Institute for Basic Research, The New York State Office for People with Developmental Disabilities;
| | - Valerie Schwenk
- The Institute for Basic Research, The New York State Office for People with Developmental Disabilities
| | | | - Carolyn Salafia
- The Institute for Basic Research, The New York State Office for People with Developmental Disabilities; Placental Analytics LLC
| | | | - Michael Joyce
- The Institute for Basic Research, The New York State Office for People with Developmental Disabilities
| | | | | | | |
Collapse
|
19
|
Nye GA, Ingram E, Johnstone ED, Jensen OE, Schneider H, Lewis RM, Chernyavsky IL, Brownbill P. Human placental oxygenation in late gestation: experimental and theoretical approaches. J Physiol 2018; 596:5523-5534. [PMID: 29377190 PMCID: PMC6265570 DOI: 10.1113/jp275633] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 01/18/2018] [Indexed: 01/26/2023] Open
Abstract
The placenta is crucial for life. It is an ephemeral but complex organ acting as the barrier interface between maternal and fetal circulations, providing exchange of gases, nutrients, hormones, waste products and immunoglobulins. Many gaps exist in our understanding of the detailed placental structure and function, particularly in relation to oxygen handling and transfer in healthy and pathological states in utero. Measurements to understand oxygen transfer in vivo in the human are limited, with no general agreement on the most appropriate methods. An invasive method for measuring partial pressure of oxygen in the intervillous space through needle electrode insertion at the time of Caesarean sections has been reported. This allows for direct measurements in vivo whilst maintaining near normal placental conditions; however, there are practical and ethical implications in using this method for determination of placental oxygenation. Furthermore, oxygen levels are likely to be highly heterogeneous within the placenta. Emerging non-invasive techniques, such as MRI, and ex vivo research are capable of enhancing and improving current imaging methodology for placental villous structure and increase the precision of oxygen measurement within placental compartments. These techniques, in combination with mathematical modelling, have stimulated novel cross-disciplinary approaches that could advance our understanding of placental oxygenation and its metabolism in normal and pathological pregnancies, improving clinical treatment options and ultimately outcomes for the patient.
Collapse
Affiliation(s)
- Gareth A Nye
- 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, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK.,St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK
| | - Emma Ingram
- 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, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK.,St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK
| | - Edward D Johnstone
- 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, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK.,St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK
| | - Oliver E Jensen
- School of Mathematics, University of Manchester, Manchester, M13 9PL, UK
| | - Henning Schneider
- Department of Obstetrics and Gynecology, Inselspital, University of Bern, CH-3010, Bern, Switzerland
| | - Rohan M Lewis
- Faculty of Medicine, University of Southampton, Southampton, SO16 6YD, UK
| | - Igor L Chernyavsky
- 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, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK.,St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK.,School of Mathematics, University of Manchester, Manchester, M13 9PL, 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, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK.,St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK
| |
Collapse
|
20
|
Perazzolo S, Lewis R, Sengers B. Modelling the effect of intervillous flow on solute transfer based on 3D imaging of the human placental microstructure. Placenta 2017; 60:21-27. [DOI: 10.1016/j.placenta.2017.10.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 09/29/2017] [Accepted: 10/10/2017] [Indexed: 01/05/2023]
|
21
|
Gestational diabetes mellitus is associated with increased pro-migratory activation of vascular endothelial growth factor receptor 2 and reduced expression of vascular endothelial growth factor receptor 1. PLoS One 2017; 12:e0182509. [PMID: 28817576 PMCID: PMC5560693 DOI: 10.1371/journal.pone.0182509] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 07/19/2017] [Indexed: 12/27/2022] Open
Abstract
Placentas from gestational diabetes mellitus (GDM) are often hypervascularized; however, participation of vascular endothelial growth factor (VEGF) and its receptors in this placental adaptation is unclear. We aimed to test whether changes in phosphorylation of tyrosine 951 or tyrosine 1175 (pY951 or pY1175) of the vascular endothelial growth factor receptor 2 (KDR) are associated with the proangiogenic state observed in placentas from GDM. We obtained placental samples from women with normal pregnancies (n = 24) or GDM (n = 18). We measured the relative expression of markers for endothelial cell number (CD31, CD34), VEGF, vascular endothelial growth factor receptor 1 (Flt-1), KDR, pY951 and pY1175 of KDR in placental homogenate. Immunohistochemistry of placental blood vessels were performed using CD34. Proliferation and migration of human umbilical vein endothelial cells (HUVEC) obtained from normal pregnancy and GDM were determined in absence or presence of conditioned medium (CM) harvested from GDM or normoglycemic HUVEC cultures. GDM was associated with more CD31 and CD34 protein compared to normal pregnancy. High number, but reduced area of placental blood vessels was found in GDM. Reduced Flt-1 levels (mRNA and protein) are associated with reduced KDR mRNA, but higher KDR protein levels in placentas from GDM. No significant changes in Y951-or Y1175-phosphorylation of KDR in placentas from GDM were found. GDM did not alter proliferation of HUVECs, but enhanced migration. Conditioned medium harvested from GDM HUVEC cultures enhanced KDR protein amount, tube formation capacity and cell migration in HUVEC isolated from normoglycemic pregnancies. The data indicate that GDM is associated with reduced expression of Flt-1 but high pro-migratory activation of KDR reflecting a proangiogenic state in GDM.
Collapse
|