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Basu R, Ganesan S, Winkler CW, Anzick SL, Martens C, Peterson KE, Fraser IDC. Identification of age-specific gene regulators of La Crosse virus neuroinvasion and pathogenesis. Nat Commun 2023; 14:2836. [PMID: 37202395 DOI: 10.1038/s41467-023-37833-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Accepted: 04/03/2023] [Indexed: 05/20/2023] Open
Abstract
One of the key events in viral encephalitis is the ability of virus to enter the central nervous system (CNS). Several encephalitic viruses, including La Crosse Virus (LACV), primarily induce encephalitis in children, but not adults. This phenomenon is also observed in LACV mouse models, where the virus gains access to the CNS of weanling animals through vascular leakage of brain microvessels, likely through brain capillary endothelial cells (BCECs). To examine age and region-specific regulatory factors of vascular leakage, we used genome-wide transcriptomics and targeted siRNA screening to identify genes whose suppression affected viral pathogenesis in BCECs. Further analysis of two of these gene products, Connexin43 (Cx43/Gja1) and EphrinA2 (Efna2), showed a substantial effect on LACV pathogenesis. Induction of Cx43 by 4-phenylbutyric acid (4-PBA) inhibited neurological disease in weanling mice, while Efna2 deficiency increased disease in adult mice. Thus, we show that Efna2 and Cx43 expressed by BCECs are key mediators of LACV-induced neuroinvasion and neurological disease.
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Affiliation(s)
- Rahul Basu
- Neuroimmunology Section, Laboratory of Persistent Viral Disease, Rocky Mountain Laboratories, NIAID, NIH, 903 S. 4th Street, MT, 59840, Hamilton, USA
- Signaling Systems Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Memorial Drive, Bethesda, MD, 20892, USA
| | - Sundar Ganesan
- Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Memorial Drive, Bethesda, MD, 20892, USA
| | - Clayton W Winkler
- Neuroimmunology Section, Laboratory of Persistent Viral Disease, Rocky Mountain Laboratories, NIAID, NIH, 903 S. 4th Street, MT, 59840, Hamilton, USA
| | - Sarah L Anzick
- Genomics Research Section, Research Technologies Branch, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 S. 4th Street, MT 59840, Hamilton, MT, USA
| | - Craig Martens
- Genomics Research Section, Research Technologies Branch, Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 903 S. 4th Street, MT 59840, Hamilton, MT, USA
| | - Karin E Peterson
- Neuroimmunology Section, Laboratory of Persistent Viral Disease, Rocky Mountain Laboratories, NIAID, NIH, 903 S. 4th Street, MT, 59840, Hamilton, USA.
| | - Iain D C Fraser
- Signaling Systems Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Memorial Drive, Bethesda, MD, 20892, USA.
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2
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Ben-Zvi A, Liebner S. Developmental regulation of barrier- and non-barrier blood vessels in the CNS. J Intern Med 2022; 292:31-46. [PMID: 33665890 DOI: 10.1111/joim.13263] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 02/01/2021] [Indexed: 12/22/2022]
Abstract
The blood-brain barrier (BBB) is essential for creating and maintaining tissue homeostasis in the central nervous system (CNS), which is key for proper neuronal function. In most vertebrates, the BBB is localized to microvascular endothelial cells that acquire barrier properties during angiogenesis of the neuroectoderm. Complex and continuous tight junctions, and the lack of fenestrae combined with low pinocytotic activity render the BBB endothelium a tight barrier for water-soluble molecules that may only enter the CNS via specific transporters. The differentiation of these unique endothelial properties during embryonic development is initiated by endothelial-specific flavours of the Wnt/β-catenin pathway in a precise spatiotemporal manner. In this review, we summarize the currently known cellular (neural precursor and endothelial cells) and molecular (VEGF and Wnt/β-catenin) mechanisms mediating brain angiogenesis and barrier formation. Moreover, we introduce more recently discovered crosstalk with cellular and acellular elements within the developing CNS such as the extracellular matrix. We discuss recent insights into the downstream molecular mechanisms of Wnt/β-catenin in particular, the recently identified target genes like Foxf2, Foxl2, Foxq1, Lef1, Ppard, Zfp551, Zic3, Sox17, Apcdd1 and Fgfbp1 that are involved in refining and maintaining barrier characteristics in the mature BBB endothelium. Additionally, we elute to recent insight into barrier heterogeneity and differential endothelial barrier properties within the CNS, focussing on the circumventricular organs as well as on the neurogenic niches in the subventricular zone and the hippocampus. Finally, open questions and future BBB research directions are highlighted in the context of taking benefit from understanding BBB development for strategies to modulate BBB function under pathological conditions.
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Affiliation(s)
- A Ben-Zvi
- From the, The Department of Developmental Biology and Cancer Research, Institute for Medical Research IMRIC, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - S Liebner
- Institute of Neurology (Edinger Institute), University Hospital, Goethe University Frankfurt, Frankfurt am Main, Germany.,Excellence Cluster Cardio-Pulmonary Systems (ECCPS), Partner Site Frankfurt, Frankfurt am Main, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Rhine-Main, Frankfurt am Main, Germany
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3
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Yan L, Moriarty RA, Stroka KM. Recent progress and new challenges in modeling of human pluripotent stem cell-derived blood-brain barrier. Theranostics 2021; 11:10148-10170. [PMID: 34815809 PMCID: PMC8581424 DOI: 10.7150/thno.63195] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 10/05/2021] [Indexed: 12/13/2022] Open
Abstract
The blood-brain barrier (BBB) is a semipermeable unit that serves to vascularize the central nervous system (CNS) while tightly regulating the movement of molecules, ions, and cells between the blood and the brain. The BBB precisely controls brain homeostasis and protects the neural tissue from toxins and pathogens. The BBB is coordinated by a tight monolayer of brain microvascular endothelial cells, which is subsequently supported by mural cells, astrocytes, and surrounding neuronal cells that regulate the barrier function with a series of specialized properties. Dysfunction of barrier properties is an important pathological feature in the progression of various neurological diseases. In vitro BBB models recapitulating the physiological and diseased states are important tools to understand the pathological mechanism and to serve as a platform to screen potential drugs. Recent advances in this field have stemmed from the use of pluripotent stem cells (PSCs). Various cell types of the BBB such as brain microvascular endothelial cells (BMECs), pericytes, and astrocytes have been derived from PSCs and synergistically incorporated to model the complex BBB structure in vitro. In this review, we summarize the most recent protocols and techniques for the differentiation of major cell types of the BBB. We also discuss the progress of BBB modeling by using PSC-derived cells and perspectives on how to reproduce more natural BBBs in vitro.
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Affiliation(s)
- Li Yan
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Rebecca A. Moriarty
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Kimberly M. Stroka
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
- Biophysics Program, University of Maryland, College Park, MD 20742, USA
- Center for Stem Cell Biology and Regenerative Medicine, University of Maryland, Baltimore, MD 21201, USA
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland, Baltimore, MD 21201, USA
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4
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Basu R, Nair V, Winkler CW, Woods TA, Fraser IDC, Peterson KE. Age influences susceptibility of brain capillary endothelial cells to La Crosse virus infection and cell death. J Neuroinflammation 2021; 18:125. [PMID: 34082753 PMCID: PMC8173794 DOI: 10.1186/s12974-021-02173-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/11/2021] [Indexed: 12/02/2022] Open
Abstract
Background A key factor in the development of viral encephalitis is a virus crossing the blood-brain barrier (BBB). We have previously shown that age-related susceptibility of mice to the La Crosse virus (LACV), the leading cause of pediatric arbovirus encephalitis in the USA, was associated with the ability of the virus to cross the BBB. LACV infection in weanling mice (aged around 3 weeks) results in vascular leakage in the olfactory bulb/tract (OB/OT) region of the brain, which is not observed in adult mice aged > 6–8 weeks. Thus, we studied age-specific differences in the response of brain capillary endothelial cells (BCECs) to LACV infection. Methods To examine mechanisms of LACV-induced BBB breakdown and infection of the CNS, we analyzed BCECs directly isolated from weanling and adult mice as well as established a model where these cells were infected in vitro and cultured for a short period to determine susceptibility to virus infection and cell death. Additionally, we utilized correlative light electron microscopy (CLEM) to examine whether changes in cell morphology and function were also observed in BCECs in vivo. Results BCECs from weanling, but not adult mice, had detectable infection after several days in culture when taken ex vivo from infected mice suggesting that these cells could be infected in vitro. Further analysis of BCECs from uninfected mice, infected in vitro, showed that weanling BCECs were more susceptible to virus infection than adult BCECs, with higher levels of infected cells, released virus as well as cytopathic effects (CPE) and cell death. Although direct LACV infection is not detected in the weanling BCECs, CLEM analysis of brain tissue from weanling mice indicated that LACV infection induced significant cerebrovascular damage which allowed virus-sized particles to enter the brain parenchyma. Conclusions These findings indicate that BCECs isolated from adult and weanling mice have differential viral load, infectivity, and susceptibility to LACV. These age-related differences in susceptibility may strongly influence LACV-induced BBB leakage and neurovascular damage allowing virus invasion of the CNS and the development of neurological disease. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02173-4.
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Affiliation(s)
- Rahul Basu
- Research and Technologies Branch, Rocky Mountain Laboratories, NIAID, NIH, 903 S. 4th Street, MT, 59840, Hamilton, USA.,Signaling Systems Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Memorial Drive, Bethesda, MD, 20892, USA
| | - Vinod Nair
- Research and Technologies Branch, Rocky Mountain Laboratories, NIAID, NIH, 903 S. 4th Street, MT, 59840, Hamilton, USA
| | - Clayton W Winkler
- Research and Technologies Branch, Rocky Mountain Laboratories, NIAID, NIH, 903 S. 4th Street, MT, 59840, Hamilton, USA
| | - Tyson A Woods
- Research and Technologies Branch, Rocky Mountain Laboratories, NIAID, NIH, 903 S. 4th Street, MT, 59840, Hamilton, USA
| | - Iain D C Fraser
- Signaling Systems Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 4 Memorial Drive, Bethesda, MD, 20892, USA
| | - Karin E Peterson
- Research and Technologies Branch, Rocky Mountain Laboratories, NIAID, NIH, 903 S. 4th Street, MT, 59840, Hamilton, USA.
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5
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Hui F, Nguyen CTO, He Z, Vingrys AJ, Gurrell R, Fish RL, Bui BV. Retinal and Cortical Blood Flow Dynamics Following Systemic Blood-Neural Barrier Disruption. Front Neurosci 2017; 11:568. [PMID: 29075176 PMCID: PMC5643486 DOI: 10.3389/fnins.2017.00568] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 09/28/2017] [Indexed: 12/11/2022] Open
Abstract
To consider whether imaging retinal vasculature may be used as a marker for cortical vessels, we compared fluorescein angiography flow dynamics before and after pharmacological disruption of blood-neural barriers. Sodium fluorescein (1%, 200 μl/kg) was intravenously delivered in anesthetized adult Long Evans rats (n = 44, brain = 18, retina = 26). In the brain cohort, a cranial window was created to allow direct visualization of surface cortical vessels. Video fluorescein angiography was captured using a rodent retinal camera at 30 frames/second and fluorescence intensity profiles were evaluated for the time to reach 50% brightness (half-rise), 50% decay (half-fall), and the plateau level of remnant fluorescence (offset, %). Cortical vessels fluoresced earlier (artery half-rise: 5.6 ± 0.2 s) and decayed faster (half-fall: 10.3 ± 0.2 s) compared to retinal vasculature. Cortical vessels also had a considerably higher offset, particularly in the capillaries/extravascular space (41.4 ± 2.7%) whereas pigment in the retina reduces such residual fluorescence. In a sub-cohort of animals, sodium deoxycholate (DOC, 0.06 M dissolved in sterile saline, 1 mL) was delivered intravenously to cause simultaneous disruption of the blood-brain and blood-retinal barriers. A separate group received saline as vehicle control. Fluorescein angiography was re-measured at 6 and 24 h after drug infusion and evaluated by comparing flow dynamics to the upper quartile (75%) of the control group. Retinal vasculature was more sensitive to DOC-induced disruption with a higher fluorescence offset at 6 h (47.3 ± 10.6%). A delayed effect was seen in cortical vessels with a higher offset evident only at 24 h (65.6 ± 10.1%). Here we have developed a method to quantitatively compare fluorescein angiography dynamics in the retina and superficial cortical vessels. Our results show that systemic disruption of blood-neural barriers causes vascular leakage in both tissues but earlier in the retina suggesting that pharmacological blood-neural barrier disruption may be detected earlier in the eye than in cortical vasculature.
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Affiliation(s)
- Flora Hui
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Christine T. O. Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Zheng He
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Algis J. Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
| | - Rachel Gurrell
- Neuroscience and Pain Research Unit, Pfizer, Cambridge, United Kingdom
| | - Rebecca L. Fish
- Neuroscience and Pain Research Unit, Pfizer, Cambridge, United Kingdom
| | - Bang V. Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Melbourne, VIC, Australia
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6
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Guerra M, Blázquez JL, Rodríguez EM. Blood-brain barrier and foetal-onset hydrocephalus, with a view on potential novel treatments beyond managing CSF flow. Fluids Barriers CNS 2017; 14:19. [PMID: 28701191 PMCID: PMC5508761 DOI: 10.1186/s12987-017-0067-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/24/2017] [Indexed: 12/12/2022] Open
Abstract
Despite decades of research, no compelling non-surgical therapies have been developed for foetal hydrocephalus. So far, most efforts have pointed to repairing disturbances in the cerebrospinal fluid (CSF) flow and to avoid further brain damage. There are no reports trying to prevent or diminish abnormalities in brain development which are inseparably associated with hydrocephalus. A key problem in the treatment of hydrocephalus is the blood–brain barrier that restricts the access to the brain for therapeutic compounds or systemically grafted cells. Recent investigations have started to open an avenue for the development of a cell therapy for foetal-onset hydrocephalus. Potential cells to be used for brain grafting include: (1) pluripotential neural stem cells; (2) mesenchymal stem cells; (3) genetically-engineered stem cells; (4) choroid plexus cells and (5) subcommissural organ cells. Expected outcomes are a proper microenvironment for the embryonic neurogenic niche and, consequent normal brain development.
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Affiliation(s)
- M Guerra
- Instituto de Anatomía, Histología y Patología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile.
| | - J L Blázquez
- Departamento de Anatomía e Histología Humana, Facultad de Medicina, Universidad de Salamanca, Salamanca, Spain
| | - E M Rodríguez
- Instituto de Anatomía, Histología y Patología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile
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7
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Review: The blood-brain barrier; protecting the developing fetal brain. Placenta 2017; 54:111-116. [DOI: 10.1016/j.placenta.2016.12.005] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 12/01/2016] [Accepted: 12/05/2016] [Indexed: 11/18/2022]
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8
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Millar LJ, Shi L, Hoerder-Suabedissen A, Molnár Z. Neonatal Hypoxia Ischaemia: Mechanisms, Models, and Therapeutic Challenges. Front Cell Neurosci 2017; 11:78. [PMID: 28533743 PMCID: PMC5420571 DOI: 10.3389/fncel.2017.00078] [Citation(s) in RCA: 206] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 03/07/2017] [Indexed: 12/11/2022] Open
Abstract
Neonatal hypoxia-ischaemia (HI) is the most common cause of death and disability in human neonates, and is often associated with persistent motor, sensory, and cognitive impairment. Improved intensive care technology has increased survival without preventing neurological disorder, increasing morbidity throughout the adult population. Early preventative or neuroprotective interventions have the potential to rescue brain development in neonates, yet only one therapeutic intervention is currently licensed for use in developed countries. Recent investigations of the transient cortical layer known as subplate, especially regarding subplate's secretory role, opens up a novel set of potential molecular modulators of neonatal HI injury. This review examines the biological mechanisms of human neonatal HI, discusses evidence for the relevance of subplate-secreted molecules to this condition, and evaluates available animal models. Neuroserpin, a neuronally released neuroprotective factor, is discussed as a case study for developing new potential pharmacological interventions for use post-ischaemic injury.
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Affiliation(s)
- Lancelot J. Millar
- Molnár Group, Department of Physiology, Anatomy and Genetics, University of OxfordOxford, UK
| | - Lei Shi
- Molnár Group, Department of Physiology, Anatomy and Genetics, University of OxfordOxford, UK
- JNU-HKUST Joint Laboratory for Neuroscience and Innovative Drug Research, College of Pharmacy, Jinan UniversityGuangzhou, China
| | | | - Zoltán Molnár
- Molnár Group, Department of Physiology, Anatomy and Genetics, University of OxfordOxford, UK
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9
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Weiler A, Volkenhoff A, Hertenstein H, Schirmeier S. Metabolite transport across the mammalian and insect brain diffusion barriers. Neurobiol Dis 2017; 107:15-31. [PMID: 28237316 DOI: 10.1016/j.nbd.2017.02.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 01/02/2017] [Accepted: 02/20/2017] [Indexed: 12/31/2022] Open
Abstract
The nervous system in higher vertebrates is separated from the circulation by a layer of specialized endothelial cells. It protects the sensitive neurons from harmful blood-derived substances, high and fluctuating ion concentrations, xenobiotics or even pathogens. To this end, the brain endothelial cells and their interlinking tight junctions build an efficient diffusion barrier. A structurally analogous diffusion barrier exists in insects, where glial cell layers separate the hemolymph from the neural cells. Both types of diffusion barriers, of course, also prevent influx of metabolites from the circulation. Because neuronal function consumes vast amounts of energy and necessitates influx of diverse substrates and metabolites, tightly regulated transport systems must ensure a constant metabolite supply. Here, we review the current knowledge about transport systems that carry key metabolites, amino acids, lipids and carbohydrates into the vertebrate and Drosophila brain and how this transport is regulated. Blood-brain and hemolymph-brain transport functions are conserved and we can thus use a simple, genetically accessible model system to learn more about features and dynamics of metabolite transport into the brain.
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Affiliation(s)
- Astrid Weiler
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Anne Volkenhoff
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Helen Hertenstein
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany
| | - Stefanie Schirmeier
- Institut für Neuro- und Verhaltensbiologie, Universität Münster, Badestr. 9, 48149 Münster, Germany.
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10
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De Bock M, Van Haver V, Vandenbroucke RE, Decrock E, Wang N, Leybaert L. Into rather unexplored terrain-transcellular transport across the blood-brain barrier. Glia 2016; 64:1097-123. [DOI: 10.1002/glia.22960] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 11/16/2015] [Accepted: 12/03/2015] [Indexed: 01/22/2023]
Affiliation(s)
- Marijke De Bock
- Physiology Group, Department of Basic Medical Sciences; Ghent University; Ghent Belgium
| | - Valérie Van Haver
- Physiology Group, Department of Basic Medical Sciences; Ghent University; Ghent Belgium
| | - Roosmarijn E. Vandenbroucke
- Inflammation Research Center, VIB; Ghent Belgium
- Department of Biomedical Molecular Biology; Ghent University; Ghent Belgium
| | - Elke Decrock
- Physiology Group, Department of Basic Medical Sciences; Ghent University; Ghent Belgium
| | - Nan Wang
- Physiology Group, Department of Basic Medical Sciences; Ghent University; Ghent Belgium
| | - Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences; Ghent University; Ghent Belgium
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11
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Soares RV, Do TM, Mabondzo A, Pons G, Chhun S. Ontogeny of ABC and SLC transporters in the microvessels of developing rat brain. Fundam Clin Pharmacol 2016; 30:107-16. [PMID: 26662930 DOI: 10.1111/fcp.12175] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 11/19/2015] [Accepted: 12/08/2015] [Indexed: 01/01/2023]
Abstract
The blood-brain barrier (BBB) is responsible for the control of solutes' concentration in the brain. Tight junctions and multiple ATP-binding cassette (ABC) and SoLute Carrier (SLC) efflux transporters protect brain cells from xenobiotics, therefore reducing brain exposure to intentionally administered drugs. In epilepsy, polymorphisms and overexpression of efflux transporters genes could be associated with pharmacoresistance. The ontogeny of these efflux transporters should also be addressed because their expression during development may be related to different brain exposure to antiepileptic drugs in the immature brain. We detected statistically significant higher expression of Abcb1b and Slc16a1 genes, and lower expression of Abcb1a and Abcg2 genes between the post-natal day 14 (P14) and the adult rat microvessels. P-gP efflux activity was also shown to be lower in P14 rats when compared with the adults. The P-gP proteins coded by rodent genes Abcb1a and Abcb1b are known to have different substrate affinities. The role of the Abcg2 gene is less clear in pharmacoresistance in epilepsy, nonetheless the coded protein Bcrp is frequently associated with drug resistance. Finally, we observed a higher expression of the Mct1 transporter gene in the P14 rat brain microvessels. Accordingly to our results, we suppose that age may be another factor influencing brain exposure to antiepileptics as a consequence of different expression patterns of efflux transporters between the adult and immature BBB.
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Affiliation(s)
- Ricardo V Soares
- Inserm U1129, Paris, France.,University Paris Descartes, Faculty of Medicine, Paris, France.,CEA, Direction des Sciences du Vivant, iBiTec-S, Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Tuan M Do
- CEA, Direction des Sciences du Vivant, iBiTec-S, Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Aloïse Mabondzo
- CEA, Direction des Sciences du Vivant, iBiTec-S, Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Gérard Pons
- Inserm U1129, Paris, France.,University Paris Descartes, Faculty of Medicine, Paris, France
| | - Stéphanie Chhun
- University Paris Descartes, Faculty of Medicine, Paris, France.,Inserm U1151, INEM, Paris, France.,APHP, Hôpital Universitaire Necker-Enfants Malades, Laboratoire d'immunologie biologique, Paris, France
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12
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Hagan N, Ben-Zvi A. The molecular, cellular, and morphological components of blood-brain barrier development during embryogenesis. Semin Cell Dev Biol 2014; 38:7-15. [PMID: 25550218 DOI: 10.1016/j.semcdb.2014.12.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/24/2014] [Accepted: 12/21/2014] [Indexed: 01/24/2023]
Abstract
The blood brain barrier (BBB) is a hallmark of blood vessels in the brain and functions to protect the brain from unwanted blood born materials, support the unique metabolic needs of the brain, and define a stable environment crucial for brain homeostasis. The temporal profile of BBB development was long debated until recent studies produced convincing evidence demonstrating that the BBB is established and functional during embryogenesis. Here we review research focused on the molecular, cellular and morphological characteristics of BBB development. Our review discusses the precise temporal profile of BBB formation, the development of endothelial cell ultrastructure and the molecular components that provide sealing and transporting properties, the molecular pathways involved in the induction of BBB specific endothelial cell differentiation, the signaling pathways driving developmental angiogenesis versus barrier-genesis, and finally the contribution of other cell types to BBB formation. We examine aspects of BBB development that are still unresolved while highlighting research tools that could provide new insight to answer these open questions.
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Affiliation(s)
- Nellwyn Hagan
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Ayal Ben-Zvi
- Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA; Department of Developmental Biology and Cancer Research, The Hebrew University of Jerusalem, Jerusalem 91120, Israel.
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13
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Saunders NR, Dreifuss JJ, Dziegielewska KM, Johansson PA, Habgood MD, Møllgård K, Bauer HC. The rights and wrongs of blood-brain barrier permeability studies: a walk through 100 years of history. Front Neurosci 2014; 8:404. [PMID: 25565938 PMCID: PMC4267212 DOI: 10.3389/fnins.2014.00404] [Citation(s) in RCA: 149] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 11/20/2014] [Indexed: 12/16/2022] Open
Abstract
Careful examination of relevant literature shows that many of the most cherished concepts of the blood-brain barrier are incorrect. These include an almost mythological belief in its immaturity that is unfortunately often equated with absence or at least leakiness in the embryo and fetus. The original concept of a blood-brain barrier is often attributed to Ehrlich; however, he did not accept that permeability of cerebral vessels was different from other organs. Goldmann is often credited with the first experiments showing dye (trypan blue) exclusion from the brain when injected systemically, but not when injected directly into it. Rarely cited are earlier experiments of Bouffard and of Franke who showed methylene blue and trypan red stained all tissues except the brain. The term “blood-brain barrier” “Blut-Hirnschranke” is often attributed to Lewandowsky, but it does not appear in his papers. The first person to use this term seems to be Stern in the early 1920s. Studies in embryos by Stern and colleagues, Weed and Wislocki showed results similar to those in adult animals. These were well-conducted experiments made a century ago, thus the persistence of a belief in barrier immaturity is puzzling. As discussed in this review, evidence for this belief, is of poor experimental quality, often misinterpreted and often not properly cited. The functional state of blood-brain barrier mechanisms in the fetus is an important biological phenomenon with implications for normal brain development. It is also important for clinicians to have proper evidence on which to advise pregnant women who may need to take medications for serious medical conditions. Beliefs in immaturity of the blood-brain barrier have held the field back for decades. Their history illustrates the importance of taking account of all the evidence and assessing its quality, rather than selecting papers that supports a preconceived notion or intuitive belief. This review attempts to right the wrongs. Based on careful translation of original papers, some published a century ago, as well as providing discussion of studies claiming to show barrier immaturity, we hope that readers will have evidence on which to base their own conclusions.
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Affiliation(s)
- Norman R Saunders
- Department of Pharmacology and Therapeutics, University of Melbourne Parkville, VIC, Australia
| | | | | | - Pia A Johansson
- Institute for Stem Cell Research, Helmholtz Center Munich Munich, Germany
| | - Mark D Habgood
- Department of Pharmacology and Therapeutics, University of Melbourne Parkville, VIC, Australia
| | - Kjeld Møllgård
- Department of Cellular and Molecular Medicine, University of Copenhagen Copenhagen, Denmark
| | - Hans-Christian Bauer
- Institute of Tendon and Bone Regeneration, Paracelsus Medical University Salzburg, Austria ; Spinal Cord Injury and Tissue Regeneration Center, Paracelsus Medical University Salzburg, Austria
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14
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Huang X, Zhang F, Sun X, Choi KY, Niu G, Zhang G, Guo J, Lee S, Chen X. The genotype-dependent influence of functionalized multiwalled carbon nanotubes on fetal development. Biomaterials 2014; 35:856-65. [PMID: 24344357 DOI: 10.1016/j.biomaterials.2013.10.027] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In many cases cancer is caused by gene deficiency that is being passed along from generation to generation. Soluble carbon nanotubes (CNTs) have shown promising applications in the diagnosis and therapy of cancer, however, the potential relationship between cancer-prone individuals and response to CNT exposure as a prerequisite for development of personalized nanomedicine, is still poorly understood. Here we report that intravenous injections of multi-walled carbon nanotubes into p53 (a well-known cancer-susceptible gene) heterozygous pregnant mice can induce p53- dependent responses in fetal development. Larger sized multi-walled carbon nanotubes moved across the blood-placenta barrier (BPB), restricted the development of fetuses, and induced brain deformity, whereas single-walled and smaller sized multi-walled carbon nanotubes showed no or less fetotoxicity. A molecular mechanism study found that multi-walled carbon nanotubes directly triggered p53-dependent apoptosis and cell cycle arrest in response to DNA damage. Based on the molecular mechanism, we also incorporated N-acetylcysteine (NAC), an FDA approved antioxidant, to prevent CNTs induced nuclear DNA damage and reduce brain development abnormalities. Our findings suggest that CNTs might have genetic background-dependent toxic effect on the normal development of the embryo, and provide new insights into protection against nanoparticle-induced toxicity in potential clinical applications.
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15
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Siegenthaler JA, Sohet F, Daneman R. 'Sealing off the CNS': cellular and molecular regulation of blood-brain barriergenesis. Curr Opin Neurobiol 2013; 23:1057-64. [PMID: 23867075 DOI: 10.1016/j.conb.2013.06.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Accepted: 06/11/2013] [Indexed: 01/24/2023]
Abstract
From their initial ingression into the neural tube to the established, adult vascular plexus, blood vessels within the CNS are truly unique. Covered by a virtually continuous layer of perivascular cells and astrocytic endfeet and connected by specialized cell-cell junctional contacts, mature CNS blood vessels simultaneously provide nutritive blood flow and protect the neural milieu from potentially disruptive or harmful molecules and cells flowing through the vessel lumen. In this review we will discuss how the CNS vasculature acquires blood-brain barrier (BBB) properties with a specific focus on recent work identifying the cell types and molecular pathways that orchestrate barriergenesis.
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Affiliation(s)
- Julie A Siegenthaler
- Department of Pediatrics, Section of Developmental Biology, University of Colorado, Denver, Aurora, CO 80045, United States.
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16
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Lippmann ES, Azarin SM, Kay JE, Nessler RA, Wilson HK, Al-Ahmad A, Palecek SP, Shusta EV. Derivation of blood-brain barrier endothelial cells from human pluripotent stem cells. Nat Biotechnol 2013; 30:783-91. [PMID: 22729031 PMCID: PMC3467331 DOI: 10.1038/nbt.2247] [Citation(s) in RCA: 517] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 04/30/2012] [Indexed: 11/09/2022]
Abstract
The blood-brain barrier (BBB) is crucial to the health of the brain and is often compromised in neurological disease. Moreover, because of its barrier properties, this endothelial interface restricts uptake of neurotherapeutics. Thus, a renewable source of human BBB endothelium could spur brain research and pharmaceutical development. Here we show that endothelial cells derived from human pluripotent stem cells (hPSCs) acquire BBB properties when co-differentiated with neural cells that provide relevant cues, including those involved in Wnt/β-catenin signaling. The resulting endothelial cells have many BBB attributes, including well-organized tight junctions, appropriate expression of nutrient transporters and polarized efflux transporter activity. Notably, they respond to astrocytes, acquiring substantial barrier properties as measured by transendothelial electrical resistance (1,450 ± 140 Ω cm2), and they possess molecular permeability that correlates well with in vivo rodent blood-brain transfer coefficients.
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Affiliation(s)
- Ethan S Lippmann
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, Madison, Wisconsin, USA
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17
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Yang FY, Lin GL, Horng SC, Chen RC. Prenatal exposure to diagnostic ultrasound impacts blood-brain barrier permeability in rats. ULTRASOUND IN MEDICINE & BIOLOGY 2012; 38:1051-1057. [PMID: 22424599 DOI: 10.1016/j.ultrasmedbio.2012.01.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Revised: 01/20/2012] [Accepted: 01/21/2012] [Indexed: 05/31/2023]
Abstract
The central nervous system vasculature consists of a tightly sealed endothelium that forms the blood-brain barrier (BBB); these blood vessels are impermeable to large-molecular-size agents. The aim of this study was to determine the influence of prenatal ultrasound exposure on blood-brain barrier (BBB) integrity as measured by the permeation of Evans blue (EB) through the BBB during the postnatal development of the rat. Diagnostic levels of ultrasound (2.89 MHz, mechanical index = 1.1, acoustic output power = 70.5 mW) for 1 h and 2 h per day, for 9 consecutive days were used on Sprague-Dawley rats. Offspring were assessed postnatally on days 10, 17, 24 and 38. Our analysis of over 139 animals reveals that, when exposed to diagnostic levels of ultrasound during embryonic development, a statistically significant amount of EB extravasation into the cerebrum and cerebellum could be detected on postnatal day 10 but not later. In addition, small changes in pup body weight, cerebrum weight and cerebellum weight were observed after relatively prolonged ultrasound exposure on all postnatal days. Taken together, these results emphasize the need for further investigation of the effects of ultrasound exposure during the potentially vulnerable period of intense BBB development in the human fetus.
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Affiliation(s)
- Feng-Yi Yang
- Department of Biomedical Imaging and Radiological Sciences, School of Biomedical Science and Engineering, National Yang-Ming University, Taipei, Taiwan.
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18
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Saunders NR, Liddelow SA, Dziegielewska KM. Barrier mechanisms in the developing brain. Front Pharmacol 2012; 3:46. [PMID: 22479246 PMCID: PMC3314990 DOI: 10.3389/fphar.2012.00046] [Citation(s) in RCA: 324] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Accepted: 02/29/2012] [Indexed: 01/24/2023] Open
Abstract
The adult brain functions within a well-controlled stable environment, the properties of which are determined by cellular exchange mechanisms superimposed on the diffusion restraint provided by tight junctions at interfaces between blood, brain and cerebrospinal fluid (CSF). These interfaces are referred to as “the” blood–brain barrier. It is widely believed that in embryos and newborns, this barrier is immature or “leaky,” rendering the developing brain more vulnerable to drugs or toxins entering the fetal circulation from the mother. New evidence shows that many adult mechanisms, including functionally effective tight junctions are present in embryonic brain and some transporters are more active during development than in the adult. Additionally, some mechanisms present in embryos are not present in adults, e.g., specific transport of plasma proteins across the blood–CSF barrier and embryo-specific intercellular junctions between neuroependymal cells lining the ventricles. However developing cerebral vessels appear to be more fragile than in the adult. Together these properties may render developing brains more vulnerable to drugs, toxins, and pathological conditions, contributing to cerebral damage and later neurological disorders. In addition, after birth loss of protection by efflux transporters in placenta may also render the neonatal brain more vulnerable than in the fetus.
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Affiliation(s)
- Norman R Saunders
- Department of Pharmacology, The University of Melbourne Parkville, VIC, Australia
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19
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Gómez‐González B, Larios HM, Escobar A. Increased transvascular transport of WGA‐peroxidase after chronic perinatal stress in the hippocampal microvasculature of the rat. Int J Dev Neurosci 2011; 29:839-46. [DOI: 10.1016/j.ijdevneu.2011.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 07/08/2011] [Accepted: 08/08/2011] [Indexed: 12/20/2022] Open
Affiliation(s)
- Beatriz Gómez‐González
- Dept. Cell Biology and PhysiologyInstituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoCiudad Universitaria04510Mexico CityMexico
| | - Horacio Merchant Larios
- Dept. Cell Biology and PhysiologyInstituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoCiudad Universitaria04510Mexico CityMexico
| | - Alfonso Escobar
- Dept. Cell Biology and PhysiologyInstituto de Investigaciones BiomédicasUniversidad Nacional Autónoma de MéxicoCiudad Universitaria04510Mexico CityMexico
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20
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Liddelow SA. Fluids and barriers of the CNS: a historical viewpoint. Fluids Barriers CNS 2011; 8:2. [PMID: 21349150 PMCID: PMC3039834 DOI: 10.1186/2045-8118-8-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 01/18/2011] [Indexed: 02/03/2023] Open
Abstract
Tracing the exact origins of modern science can be a difficult but rewarding pursuit. It is possible for the astute reader to follow the background of any subject through the many important surviving texts from the classical and ancient world. While empirical investigations have been described by many since the time of Aristotle and scientific methods have been employed since the Middle Ages, the beginnings of modern science are generally accepted to have originated during the 'scientific revolution' of the 16th and 17th centuries in Europe. The scientific method is so fundamental to modern science that some philosophers consider earlier investigations as 'pre-science'. Notwithstanding this, the insight that can be gained from the study of the beginnings of a subject can prove important in the understanding of work more recently completed. As this journal undergoes an expansion in focus and nomenclature from cerebrospinal fluid (CSF) into all barriers of the central nervous system (CNS), this review traces the history of both the blood-CSF and blood-brain barriers from as early as it was possible to find references, to the time when modern concepts were established at the beginning of the 20th century.
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21
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Runkle EA, Antonetti DA. The blood-retinal barrier: structure and functional significance. Methods Mol Biol 2011; 686:133-48. [PMID: 21082369 DOI: 10.1007/978-1-60761-938-3_5] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Formation and maintenance of the blood-retinal barrier is required for proper vision and loss of this barrier contributes to the pathology of a wide number of retinal diseases. The retina is responsible for converting visible light into the electrochemical signal interpreted by the brain as vision. Multiple cell types are required for this function, which are organized into eight distinct cell layers. These neural and glial cells gain metabolic support from a unique vascular structure that provides the necessary nutrients while minimizing interference with light sensing. In addition to the vascular contribution, the retina also possesses an epithelial barrier, the retinal pigment epithelium, which is located at the posterior of the eye and controls exchange of nutrients with the choroidal vessels. Together the vascular and epithelial components of the blood-retinal barrier maintain the specialized environment of the neural retina. Both the vascular endothelium and pigment epithelium possess a well-developed junctional complex that includes both adherens and tight junctions conferring a high degree of control of solute and fluid permeability. Understanding induction and regulation of the blood-retinal barrier will allow the development of therapies aimed at restoring the barrier when compromised in disease or allowing the specific transport of therapies across this barrier when needed. This chapter will highlight the anatomical structure of the blood-retinal barrier and explore the molecular structure of the tight junctions that provide the unique barrier properties of the blood--retinal barrier.
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Affiliation(s)
- E Aaron Runkle
- Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, USA
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22
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The role of the blood-CNS barrier in CNS disorders and their treatment. Neurobiol Dis 2009; 37:3-12. [PMID: 19664711 DOI: 10.1016/j.nbd.2009.07.029] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 07/30/2009] [Accepted: 07/30/2009] [Indexed: 01/16/2023] Open
Abstract
The physical barrier between blood and the CNS (the blood-brain barrier, the blood-spinal cord barrier and the blood-CSF barrier) protects the CNS from both toxic and pathogenic agents in the blood. It is now clear that disruption of the blood-CNS barrier plays a key role in a number of CNS disorders, particularly those associated with neurodegeneration. Such disruption is inevitably accompanied by inflammatory change, as immune cells and immune mediators gain access to the brain or spinal cord. The blood-CNS barrier also presents a major obstacle for potential CNS medicines. Robust methods to assess CNS permeation are therefore essential for CNS drug discovery, particularly when brain pharmacokinetics are taken into account and especially when such measures are linked to neurochemical, physiological, behavioural or neuroimaging readouts of drug action. Drug candidates can be successfully designed to cross the blood-CNS barrier, but for those that can't there is the possibility of entry with a delivery system that facilitates the movement of drug candidate across the blood-CNS barrier.
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23
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Chen W, Ostrowski RP, Obenaus A, Zhang JH. Prodeath or prosurvival: two facets of hypoxia inducible factor-1 in perinatal brain injury. Exp Neurol 2008; 216:7-15. [PMID: 19041643 DOI: 10.1016/j.expneurol.2008.10.016] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Revised: 09/12/2008] [Accepted: 10/24/2008] [Indexed: 01/13/2023]
Abstract
Hypoxia, which occurs in the brain when oxygen availability drops below the normal level, is a major cause of perinatal hypoxic-ischemic injury (HII). The transcriptional factor hypoxia inducible factor-1 (HIF-1) is a key regulator in the pathophysiological response to the stress of hypoxia. Genes regulated by HIF-1 are involved in energy metabolism, erythropoiesis, angiogenesis, vasodilatation, cell survival and apoptosis. Compared with the adult brain, the neonatal brain is different in physiological structure, function, cellular composition and signaling pathway related gene activation and response after hypoxia. The purpose of this review is to determine if developmental susceptibility of the brain after hypoxic/ischemic injury is related to HIF-1alpha, which also plays a pivotal role in the normal brain development. HIF-1alpha regulates both prosurvival and prodeath responses in the neonatal brain and various mechanisms underlie the apparent contradictory effects, including duration of ischemic injury and severity, cell-types, and/or dependent on the nature of the stimulus after HII. Studies report an excessive induction of HIF-1 in the immature brain, which suggests that a cell death promoting role of HIF may prevail. Inhibition of HIF-1alpha and targeted activation of its prosurvival genes appear as a favorable therapeutic strategy. However, a better understanding of multifaceted HIF-1 function during brain development is required to explore potential targets for further therapeutic interventions in the neonate.
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Affiliation(s)
- Wanqiu Chen
- Department of Physiology, Loma Linda University, Loma Linda, CA 92354, USA
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24
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Abstract
Endothelial cells, which form the inner cellular lining of blood vessels and lymphatics, display remarkable heterogeneity in structure and function. This is the first of a 2-part review focused on phenotypic heterogeneity of blood vessel endothelium. This review provides an historical perspective of our understanding of endothelial heterogeneity, discusses the scope of phenotypic diversity across the vascular tree, and addresses proximate and evolutionary mechanisms of endothelial cell heterogeneity. The overall goal is to underscore the importance of phenotypic heterogeneity as a core property of the endothelium.
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Affiliation(s)
- William C Aird
- Division of Molecular and Vascular Medicine, Department of Medicine, and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass 02215, USA.
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25
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Weidenfeller C, Svendsen CN, Shusta EV. Differentiating embryonic neural progenitor cells induce blood-brain barrier properties. J Neurochem 2007; 101:555-65. [PMID: 17254017 PMCID: PMC2657050 DOI: 10.1111/j.1471-4159.2006.04394.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The blood-brain barrier (BBB) is a multifunctional endothelial interface separating the bloodstream from the brain interior. Although the mature BBB is well characterized, the embryonic development of this complex system remains poorly understood. Embryonic neural progenitor cells (NPC) are a potential inductive cell type populating the developing brain, and their ability to influence BBB properties was therefore examined. When puromycin-purified brain microvascular endothelial cells (BMEC) were co-cultured with embryonic NPC in a two-compartment Transwell system, the BMEC exhibited enhanced barrier properties in the form of increased transendothelial electrical resistance (TEER) and decreased permeability to the small molecule tracer, sodium fluorescein. These changes required the presence of NPC in the early stages of differentiation and were accompanied by alterations in the fidelity of BMEC tight junctions as indicated by occludin, claudin 5, and zonula occluden-1 redistribution at cell-cell borders. In contrast to the findings with NPC, post-natal astrocytes elicited a delayed, but longer duration response in BMEC TEER. BMEC co-culture also suppressed neuronal differentiation of NPC indicating a reciprocal signaling between the two cell populations. This study demonstrates that NPC-BMEC interactions are prevalent and for the first time demonstrates that NPC are capable of inducing BBB properties.
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Affiliation(s)
- Christian Weidenfeller
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Clive N. Svendsen
- Departments of Anatomy and Neurology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Eric V. Shusta
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
- To whom correspondence should be addressed: Eric V. Shusta, Department of Chemical and Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706, , Ph: (608) 265-5103, Fax: (608) 262-5434
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26
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Kraus J, Oschmann P. The impact of interferon-beta treatment on the blood-brain barrier. Drug Discov Today 2006; 11:755-62. [PMID: 16846804 DOI: 10.1016/j.drudis.2006.06.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Revised: 05/24/2006] [Accepted: 06/09/2006] [Indexed: 01/09/2023]
Abstract
Changes in the blood-brain barrier (BBB) are crucial to the pathogenesis of multiple sclerosis (MS). There are currently few established treatments for MS, and interferon-beta (IFN-beta) therapy is one of the most promising - proposed to act as an immunomodulator of the cytokine network reducing inflammatory damage. However, there is increasing evidence that direct effects on the BBB could also be relevant. This review surveys the evidence that IFN-beta stabilizes the BBB, and that this process itself might be the key target. Understanding IFN-beta-derived changes at the BBB will not only provide new insights in the pathogenesis of MS but will also be helpful to develop new, more-specific drugs for MS treatment.
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Affiliation(s)
- Jörg Kraus
- Paracelsus Private Medical University and Salzburger Landesklinken, Christian-Doppler-Klinik, Department of Neurology, Ignaz-Harrer-Strasse 79, 5020 Salzburg, Austria.
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27
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Anstrom JA, Thore CR, Moody DM, Brown WR. Immunolocalization of tight junction proteins in blood vessels in human germinal matrix and cortex. Histochem Cell Biol 2006; 127:205-13. [PMID: 16957815 DOI: 10.1007/s00418-006-0232-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2006] [Indexed: 01/21/2023]
Abstract
Brain development occurs in a specialized environment maintained by a blood-brain barrier (BBB). An important structural element of the BBB is the endothelial tight junction (TJ). TJs are present during the embryonic period, but BBB impermeability accrues over an extended gestational interval. In studies of human premature infants, we used immunomicroscopy to determine if amounts of the TJ proteins ZO-1, claudin and occludin increase with gestational age in vessels of germinal matrix (GM) and cortex. By 24 weeks postconception (PC), TJ proteins were present in both GM and cortical vessels, but immunoreactivity in the GM of the youngest subjects was less than in older subjects. At 24 weeks PC, TJ protein immunoreactivity in GM vessels was less than in cortical vessels suggesting that TJ maturation progresses along a superficial to deep brain axis. This concept correlates with conclusions from previous analyses of the expression of brain endothelial cell alkaline phosphatase (AP) activity. AP appears in cortical vessels before appearing in deep white matter and GM vessels. Together, these data indicate that differentiation of some functional specializations is still in progress in GM vessels during the third trimester. This maturation could relate to the pathogenesis of germinal matrix hemorrhage-intraventricular hemorrhage.
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Affiliation(s)
- John A Anstrom
- Department of Radiology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA,
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28
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Ek CJ, Dziegielewska KM, Stolp H, Saunders NR. Functional effectiveness of the blood-brain barrier to small water-soluble molecules in developing and adult opossum (Monodelphis domestica). J Comp Neurol 2006; 496:13-26. [PMID: 16528724 PMCID: PMC2634607 DOI: 10.1002/cne.20885] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We have evaluated a small water-soluble molecule, biotin ethylenediamine (BED, 286 Da), as a permeability tracer across the blood-brain barrier. This molecule was found to have suitable characteristics in that it is stable in plasma, has low plasma protein binding, and appears to behave in a similar manner across brain barriers as established by permeability markers such as sucrose. BED, together with a 3000-Da biotin-dextran (BDA3000), was used to investigate the effectiveness of tight junctions in cortical vessels during development and adulthood of a marsupial opossum (Monodelphis domestica). Marsupial species are born at an early stage of brain development when cortical vessels are just beginning to appear. The tracers were administered systemically to opossums at various ages and localized in brains with light and electron microscopy. In adults, the tight junctions restricted the movement of both tracers. In neonates, as soon as vessels grow into the neocortex, their tight junctions are functionally restrictive, a finding supported by the presence of claudin-5 in endothelial cells. However, both tracers are also found within brain extracellular space soon after intraperitoneal administration. The main route of entry for the tracers into immature neocortex appears to be via the cerebrospinal fluid over the outer (subarachnoid) and inner (ventricular) surfaces of the brain. These experiments demonstrate that the previously described higher permeability of barriers to small molecules in the developing brain does not seem to be due to leakiness of cerebral endothelial tight junctions, but to a route of entry probably via the choroid plexuses and cerebrospinal fluid.
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Affiliation(s)
- Carl Joakim Ek
- Department of Pharmacology, University of Melbourne, Parkville 3001, Australia
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29
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Haseloff RF, Blasig IE, Bauer HC, Bauer H. In Search of the Astrocytic Factor(s) Modulating Blood–Brain Barrier Functions in Brain Capillary Endothelial Cells In Vitro. Cell Mol Neurobiol 2005; 25:25-39. [PMID: 15962507 DOI: 10.1007/s10571-004-1375-x] [Citation(s) in RCA: 191] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
(1) The blood-brain barrier (BBB) is formed by brain capillary endothelial cells (ECs). There are various cell types, in particular astrocytes, but also pericytes and neurons, located in close vicinity to the capillary ECs which may influence formation and function of the BBB. Based on this consideration, this paper discusses various aspects of the influence of the surrounding cells on brain capillary ECs with special focus on the role of astrocytes. (2) Based on the morphology of the BBB, important aspects of brain EC functions are summarized, such as transport functions and maintenance of low paracellular permeability. Moreover, various facets are discussed with respect to the influence of astrocytes, pericytes, microglia, and neurons on the BBB. Data on the role of glial cells in the ontogenesis of the BBB are presented subsequently. The knowledge on this subject is far from being complete, however, these data imply that the neural/neuronal environment rather than glial cells may be of importance in the maturation of the barrier. (3) The role of glial cells in the induction and maintenance of the BBB is discussed under physiological as well as pathological conditions. Although the literature presents manifold evidence for a great variety of effects induced by astroglia, there are also many controversies, which may result from different cellular models and experimental conditions used in the respective studies. Numerous factors secreted by astrocytes have been shown to induce a BBB phenotype. On the molecular level, increased expression of barrier-relevant proteins (e.g., tight junction proteins) is documented in the presence of astrocyte-derived factors, and many studies demonstrate the improvement of physiological parameters, such as increased transendothelial resistance and decreased paracellular permeability, in different in vitro models of the BBB. Moreover, one has to take into account that the interaction of brain ECs and astrocytes is bi-directional, and that the other cell types surrounding the brain microvasculature also contribute to BBB function or dysfunction, respectively. (4) In conclusion, it is expected that the present and future research focused on molecular mechanisms and signaling pathways will produce new and exciting insights into the complex network of BBB regulation: the cornerstone is laid.
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Affiliation(s)
- R F Haseloff
- Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, D-13125 Berlin, Germany.
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Abstract
The pathogenesis of hypoxic-ischemic brain injury in the term infant is multifactorial and complex. Over the past decade the investigative emphasis has turned to cellular and molecular mechanisms of injury, and it has been increasingly recognized that the neonatal brain differs vastly from the adult brain in terms of response to hypoxia-ischemia. This review will discuss the initiation and evolution of brain injury in the term neonate, and the inherent biochemical and physiologic qualities of the neonatal brain that make its response to hypoxia-ischemia unique. Attention will be given to specific areas of investigation including excitotoxicity, oxidative stress, and inflammation. The coalescence of these entities to a final common pathway of hypoxic-ischemic brain injury will be emphasized.
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Affiliation(s)
- Claire McLean
- Division of Neonatology, Department of Pediatrics, University of California, Neonatal Brain Disorders Center, San Francisco, CA 94143-0663, USA
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31
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Erecinska M, Cherian S, Silver IA. Energy metabolism in mammalian brain during development. Prog Neurobiol 2004; 73:397-445. [PMID: 15313334 DOI: 10.1016/j.pneurobio.2004.06.003] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2004] [Accepted: 06/09/2004] [Indexed: 12/28/2022]
Abstract
Production of energy for the maintenance of ionic disequilibria necessary for generation and transmission of nerve impulses is one of the primary functions of the brain. This review attempts to link the plethora of information on the maturation of the central nervous system with the ontogeny of ATP metabolism, placing special emphasis on variations that occur during development in different brain regions and across the mammalian species. It correlates morphological events and markers with biochemical changes in activities of enzymes and pathways that participate in the production of ATP. The paper also evaluates alterations in energy levels as a function of age and, based on the tenet that ATP synthesis and utilization cannot be considered in isolation, investigates maturational profiles of the key processes that utilize energy. Finally, an attempt is made to assess the relevance of currently available animal models to improvement of our understanding of the etiopathology of various disease states in the human infant. This is deemed essential for the development and testing of novel strategies for prevention and treatment of several severe neurological deficits.
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Affiliation(s)
- Maria Erecinska
- Department of Anatomy, School of Veterinary Science, Southwell Street, Bristol BS2 8EJ, UK.
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Ballabh P, Braun A, Nedergaard M. The blood-brain barrier: an overview: structure, regulation, and clinical implications. Neurobiol Dis 2004; 16:1-13. [PMID: 15207256 DOI: 10.1016/j.nbd.2003.12.016] [Citation(s) in RCA: 1479] [Impact Index Per Article: 74.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2003] [Revised: 11/21/2003] [Accepted: 12/10/2003] [Indexed: 02/08/2023] Open
Abstract
The blood-brain barrier (BBB) is a diffusion barrier, which impedes influx of most compounds from blood to brain. Three cellular elements of the brain microvasculature compose the BBB-endothelial cells, astrocyte end-feet, and pericytes (PCs). Tight junctions (TJs), present between the cerebral endothelial cells, form a diffusion barrier, which selectively excludes most blood-borne substances from entering the brain. Astrocytic end-feet tightly ensheath the vessel wall and appear to be critical for the induction and maintenance of the TJ barrier, but astrocytes are not believed to have a barrier function in the mammalian brain. Dysfunction of the BBB, for example, impairment of the TJ seal, complicates a number of neurologic diseases including stroke and neuroinflammatory disorders. We review here the recent developments in our understanding of the BBB and the role of the BBB dysfunction in CNS disease. We have focused on intraventricular hemorrhage (IVH) in premature infants, which may involve dysfunction of the TJ seal as well as immaturity of the BBB in the germinal matrix (GM). A paucity of TJs or PCs, coupled with incomplete coverage of blood vessels by astrocyte end-feet, may account for the fragility of blood vessels in the GM of premature infants. Finally, this review describes the pathogenesis of increased BBB permeability in hypoxia-ischemia and inflammatory mechanisms involving the BBB in septic encephalopathy, HIV-induced dementia, multiple sclerosis, and Alzheimer disease.
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Affiliation(s)
- Praveen Ballabh
- Department of Pediatrics, New York Medical College and Westchester Medical Center, Valhalla, NY 10595, USA.
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Roux KJ, Amici SA, Notterpek L. The temporospatial expression of peripheral myelin protein 22 at the developing blood-nerve and blood-brain barriers. J Comp Neurol 2004; 474:578-88. [PMID: 15174074 DOI: 10.1002/cne.20154] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Peripheral myelin protein 22 (PMP22), also known as growth arrest-specific gene 3 (gas3), is a tetraspan membrane protein whose misexpression is associated with demyelinating peripheral neuropathies. Although the function of PMP22 in Schwann cells is unknown, the protein is found at intercellular junctions of various epithelia and endothelia. To begin to elucidate the role of PMP22 at cell junctions, we examined the temporal expression and protein localization during development and maturation of the rat blood-nerve barrier (BNB) and blood-brain barrier (BBB). Developing and adult rat sciatic nerves and brains were coimmunostained for PMP22 and known junctional proteins including zonula occludens-1 (ZO-1), occludin, and claudin-5. Prior to the maturation of the BNB and BBB and detection of the tight junction protein occludin, PMP22 is present at ZO-1 positive endothelial junctions of the sciatic nerve and brain cortex. The subcellular localization of PMP22 in cultured brain endothelia was confirmed by internalization with ZO-1 after EGTA-induced disruption of cell junctions. In choroid epithelia, PMP22 is detected along with occludin and ZO-1 as early as embryonic day 15 (E15). In agreement, PMP22 message is elevated in P1 rat brain microvasculature and choroid epithelia, compared with total cortex. Additionally, neuroepithelial cell junctions in the embryonic rat brain are immunoreactive for PMP22, ZO-1, and beta-catenin but not occludin. Together, these studies identify PMP22 as an early constituent of intercellular junctions in the developing and mature rat BNB and BBB.
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Affiliation(s)
- Kyle J Roux
- Department of Neuroscience, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida 32610, USA
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Lewandowski TA, Ponce RA, Charleston JS, Hong S, Faustman EM. Changes in cell cycle parameters and cell number in the rat midbrain during organogenesis. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 141:117-28. [PMID: 12644255 DOI: 10.1016/s0165-3806(03)00004-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We employed 5-bromo-2'-deoxyuridine (BrdU) labeling to identify in vivo changes in the cell cycle patterns of the rat midbrain during the major period of midbrain organogenesis, gestational days (gd) 11 to 16. We also used quantitative stereology to determine changes in absolute cell numbers during these gestational time points. Between gd 12 and 16, the length of S-phase did not change significantly while the fraction of cycling cells decreased from 73 to 11%. The average cell cycle length was determined to be 15 h on gd 12 and 17 h on gd 16, the difference not being statistically significant. The cell number in the midbrain increased from 1.3E5 cells on gd 11 to 1.7E7 cells on gd 16. On gd 12 and gd 13, there was a significant negative correlation between litter position and midbrain cell number, the effect diminishing on later days of gestation. The combined use of quantitative stereology and flow cytometry to study brain development represents a novel application that allows for simultaneous evaluation of changes in cell proliferation kinetics and the resulting effect of those kinetic changes on embryonic midbrain development.
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Affiliation(s)
- Thomas A Lewandowski
- Department of Environmental Health, University of Washington, Seattle, WA 98105, USA
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Wolburg H, Lippoldt A. Tight junctions of the blood-brain barrier: development, composition and regulation. Vascul Pharmacol 2002; 38:323-37. [PMID: 12529927 DOI: 10.1016/s1537-1891(02)00200-8] [Citation(s) in RCA: 779] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1. The blood-brain barrier is essential for the maintenance and regulation of the neural microenvironment. The main characteristic features of blood-brain barrier endothelial cells are an extremely low rate of transcytotic vesicles and a restrictive paracellular diffusion barrier. 2. Endothelial blood-brain barrier tight junctions differ from epithelial tight junctions, not only by distinct morphological and molecular properties, but also by the fact that endothelial tight junctions are more sensitive to microenvironmental than epithelial factors. 3. Many ubiquitous molecular tight junction components have been identified and characterized including claudins, occludin, ZO-1, ZO-2, ZO-3, cingulin and 7H6. Signaling pathways involved in tight junction regulation include G-proteins, serine-, threonine- and tyrosine-kinases, extra and intracellular calcium levels, cAMP levels, proteases and cytokines. Common to most of these pathways is the modulation of cytoskeletal elements and the connection of tight junction transmembrane molecules to the cytoskeleton. Additionally, crosstalk between components of the tight junction- and the cadherin-catenin system of the adherens junction suggests a close functional interdependence of the two cell-cell contact systems. 4. Important new molecular aspects of tight junction regulation were recently elucidated. This review provides an integration of these new results.
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Affiliation(s)
- Hartwig Wolburg
- Institute of Pathology, University of Tübingen, Liebermeisterstr. 8, D-72076 Tübingen, Germany.
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Ghabriel MN, Zhu C, Reilly PL, Blumbergs PC, Manavis J, Finnie JW. Toxin-induced vasogenic cerebral oedema in a rat model. ACTA NEUROCHIRURGICA. SUPPLEMENT 2001; 76:231-6. [PMID: 11450014 DOI: 10.1007/978-3-7091-6346-7_47] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Vasogenic cerebral oedema (VCO) was induced in Hooded Wistar rats by intraperitoneal injection of Clostridium perfringens type D epsilon prototoxin. Animals were killed, 1 h to 14 d postinjection, by perfusion fixation under general anaesthesia. VCO was detected by the presence of endogenous albumin in the brain, visualised by immunocytochemistry. As early as 1 h postinjection, albumin was detected in the walls of cerebral microvessels. Maximal diffuse leakage within the neural parenchyma was seen at 24 and 48 h and immunoreactivity was still present at 4 d. At 7 d only few foci were seen, and at 14 d albumin distribution was similar to that in controls. Ultrastructural assessment of the microvessels showed swelling of many astrocytic processes and abnormalities of the endothelial cells varying from swelling with loss of cytoplasmic organelles to cells showing increased electron density. Immunostaining for the endothelial barrier antigen (EBA) showed strongly immunoreactive vessels throughout normal brains. Experimental animals showed partial reduction in EBA expression, most evident at 24 and 48 h, with gradual recovery to normal by 14 d. The exact role that EBA plays in the intact BBB remains obscure.
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Affiliation(s)
- M N Ghabriel
- Department of Anatomical Sciences, University of Adelaide, Australia
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Nakai A, Taniuchi Y, Asakura H, Oya A, Yokota A, Koshino T, Araki T. Developmental changes in mitochondrial activity and energy metabolism in fetal and neonatal rat brain. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2000; 121:67-72. [PMID: 10837893 DOI: 10.1016/s0165-3806(00)00025-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Experiments were undertaken to investigate mitochondrial activity and energy metabolism in the developing rat brain from the late fetal stage to the neonatal stage. Samples of cerebral cortical tissue were obtained from fetuses at 14, 16, 18, and 20 days of gestation, and from pups at 1 h, 1 day and 7 days after birth. Mitochondrial respiration was measured polarographically using homogenates. Fetal and neonatal brains were frozen in situ and fluorometric enzymatic techniques were used for the analysis of ATP, ADP, AMP, and lactate. In the fetal brain, there was a gradual increase in stimulated (+ADP) and uncoupled respiratory rates using glutamate and malate as substrates, from 14 days to 20 days of gestation, together with a moderate increase in ATP concentration and in the sum total of adenine nucleotides, and a significant decrease in lactate. Since non-stimulated (-ADP) respiratory rates did not change with increasing gestational age, the respiratory control ratio appeared to increase over the same period. An increase in mitochondrial activity was more pronounced immediately after birth, together with a marked increase in ATP concentration and in the sum total of adenine nucleotides. The highest rate of mitochondrial respiration was observed in 1-hour-old pups. These results indicate that, in the rat brain, there is maturation of oxidative metabolism in mitochondria that is initiated in late gestation. Acceleration in mitochondrial respiration occurs immediately after birth in order to maintain high-energy phosphate levels, and this may be crucial for the successful outcome of the newborn.
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Affiliation(s)
- A Nakai
- Department of Obstetrics and Gynecology, Tama Nagayama Hospital, Nippon Medical School, 1-7-1 Nagayama, Tama-shi, 206-8512, Tokyo, Japan. Nakai.Akihito/
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38
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Stewart PA. Endothelial vesicles in the blood-brain barrier: are they related to permeability? Cell Mol Neurobiol 2000; 20:149-63. [PMID: 10696507 DOI: 10.1023/a:1007026504843] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1. Macromolecules cross capillary walls via large vascular pores that are thought to be formed by plasmalemmal vesicles. Early hypotheses suggested that vesicles transferred plasma constituents across the endothelial wall either by a "shuttle" mechanism or by fusing to form transient patent channels for diffusion. Recent evidence shows that the transcytotic pathway involves both movement of vesicles within the cell and a series of fusions and fissions of the vesicular and cellular membranes. 2. The transfer of macromolecules across the capillary wall is highly specific and is mediated by receptors incorporated into specific membrane domains. Therefore, despite their morphological similarity, endothelial vesicles from heterogeneous populations in which the predominant receptor proteins incorporated in their membranes define the functions of individual vesicles. 3. Blood-brain barrier capillaries have very low permeabilities to most hydrophilic molecules. Their low permeability to macromolecules has been presumed to be due to an inhibition of the transcytotic mechanism, resulting in a low density of endothelial vesicles. 4. A comparison of vesicular densities and protein permeabilities in a number of vascular beds shows only a very weak correlation, therefore vesicle numbers alone cannot be used to predict permeability to macromolecules. 5. Blood-brain barrier capillaries are fully capable of transcytosing specific proteins, for example, insulin and transferrin, although the details are still somewhat controversial. 6. It has recently been shown that the albumin binding protein gp60 (also known as albondin), which facilitates the transcytosis of native albumin in other vascular beds, is virtually absent in brain capillaries. 7. It seems likely that the low blood-brain barrier permeability to macromolecules may be due to a low level of expression of specific receptors, rather than to an inhibition of the transcytosis mechanism.
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Affiliation(s)
- P A Stewart
- Department of Surgery, University of Toronto, Ontario, Canada.
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Abstract
1. Fenestrated vessels can be reversibly induced in brain by agents that stimulate urokinase production. This plasminogen activator, like vascular endothelial growth factor and metalloproteinases, is secreted by tumor cells and may account for induction of fenestrated vessels. Why only some of the brain's barrier vessels are converted to fenestrated vessels is unknown. 2. The structures responsible for the filtering of solutes by fenestrated vessels may be the same as those of continuous, less permeable vessels: the glycocalyx on the surfaces of the endothelial cells and the subendothelial basal lamina. 3. Solutes leaving the cerebral ventricles immediately enter the interstitial clefts between the cells lining the ventricles. A fraction of a variety of solutes, injected into CSF compartments, is retained by subendothelial basal lamina, from which the solutes may be released in a regulated way. 4. The brain's CSF and interstitial clefts are the conduits for nonsynaptic volume transmission of diffusible signals, e.g., ions, neurotransmitters, and hormones. This type of transmission could be abetted by a parallel, cell-to-cell volume transmission mediated by gap junctions between astrocytes bordering CSF compartments and parenchymal astrocytes. 5. The width and contents of the interstitial clefts in fetal brain permit cell migration and outgrowth of neurites. The contents of the narrower and different interstitial clefts of mature brain permit solute convection but must be enzymatically degraded in order for cells to migrate through it.
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Affiliation(s)
- M W Brightman
- Laboratory of Neurobiology, National Institutes of Health, Bethesda, Maryland 20892-4062, USA.
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Abstract
1. The blood-brain barrier is essential for the maintenance and regulation of the neural microenvironment. The blood-brain barrier endothelial cells comprise an extremely low rate of transcytotic vesicles and a restrictive paracellular diffusion barrier. The latter is realized by the tight junctions between the endothelial cells of the brain microvasculature, which are subject of this review. Morphologically, blood-brain barrier-tight junctions are more similar to epithelial tight junctions than to endothelial tight junctions in peripheral blood vessels. 2. Although blood-brain barrier-tight junctions share many characteristics with epithelial tight junctions, there are also essential differences. However, in contrast to tight junctions in epithelial systems, structural and functional characteristics of tight junctions in endothelial cells are highly sensitive to ambient factors. 3. Many ubiquitous molecular constituents of tight junctions have been identified and characterized including claudins, occludin, ZO-1, ZO-2, ZO-3, cingulin, and 7H6. Signaling pathways involved in tight junction regulation comprise, among others, G-proteins, serine, threonine, and tyrosine kinases, extra- and intracellular calcium levels, cAMP levels, proteases, and TNF alpha. Common to most of these pathways is the modulation of cytoskeletal elements which may define blood-brain barrier characteristics. Additionally, cross-talk between components of the tight junction- and the cadherin-catenin system suggests a close functional interdependence of the two cell-cell contact systems. 4. Recent studies were able to elucidate crucial aspects of the molecular basis of tight junction regulation. An integration of new results into previous morphological work is the central intention of this review.
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Affiliation(s)
- U Kniesel
- Institute of Pathology, University of Tübingen, Germany
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Abstract
1. The term "blood-brain barrier" describes a range of mechanisms that control the exchange of molecules between the internal environment of the brain and the rest of the body. 2. The underlying morphological feature of these barriers is the presence of tight junctions which are present between cerebral endothelial cells and between choroid plexus epithelial cells. These junctions are present in blood vessels in fetal brain and are effective in restricting entry of proteins from blood into brain and cerebrospinal fluid. However, some features of the junctions appear to mature during brain development. 3. Although proteins do not penetrate into the extracellular space of the immature brain, they do penetrate into cerebrospinal fluid by a mechanism that is considered in the accompanying review (Dziegielewska et al., 2000). 4. In the immature brain there are additional morphological barriers at the interface between cerebrospinal fluid and brain tissue: strap junctions at the inner neuroependymal surface and these and other intercellular membrane specializations at the outer (piaarachnoid) surface. These barriers disappear later in development and are absent in the adult. 5. There is a decline in permeability to low molecular weight lipid-insoluble compounds during brain development which appears to be due mainly to a decrease in the intrinsic permeability of the blood-brain and blood-cerebrospinal fluid interfaces.
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DeVane CL, Simpkins JW, Boulton DW, Laizure SC, Miller RL. Disposition of morphine in tissues of the pregnant rat and foetus following single and continuous intraperitoneal administration to the mother. J Pharm Pharmacol 1999; 51:1283-7. [PMID: 10632086 DOI: 10.1211/0022357991776859] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Foetal exposure to maternally administered opiates such as morphine represent a serious human health problem but disposition studies in man are difficult to perform. Morphine disposition was therefore investigated in pregnant rats and their foetuses near term as a model. Disposition was examined either following intraperitoneal dosing as a single dose or continuous infusion. A high-pressure liquid chromatography assay for morphine in plasma and tissue was developed and validated. Following the single morphine dose, foetal distribution was rapid and concentrations in foetal and placental tissue were from 2.6 (whole foetus) to 27.6 (placenta) times higher compared with maternal plasma. The rank order of the area under the concentration vs time curve (AUC) of morphine in tissues was: placenta > or = foetal liver > foetal brain > whole foetus > maternal brain. The foetal brain to maternal brain AUC ratio for morphine was 9.5, suggesting large differences in their blood-brain barrier permeability. Following continuous administration of morphine there were significant linear relationships between maternal plasma and tissue concentrations with the same rank order as the single dose study. However, following continuous administration the relative amount of morphine in placenta and foetal liver was reduced by half and one-third, respectively, compared with the single dose study. These results document why the rat foetus is particularly susceptible to the pharmacodynamic effects of morphine following maternal administration.
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Affiliation(s)
- C L DeVane
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston 29425, USA.
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Wolburg H, Liebner S, Reichenbach A, Gerhardt H. The pecten oculi of the chicken: a model system for vascular differentiation and barrier maturation. INTERNATIONAL REVIEW OF CYTOLOGY 1999; 187:111-59. [PMID: 10212979 DOI: 10.1016/s0074-7696(08)62417-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The pecten oculi is a convolute of blood vessels in the vitreous body of the avian eye. This structure is well known for more than a century, but its functions are still a matter of controversies. One of these functions must be the formation of a blood-retina barrier because there is no diffusion barrier for blood-borne compounds available between the pecten and the retina. Surprisingly, the blood-retina barrier characteristics of this organ have not been studied so far, although the pecten oculi may constitute a fascinating model of vascular differentiation and barrier maturation: Pectinate endothelial cells grow by angiogenesis from the ophthalmotemporal artery into the pecten primordium and consecutively gain barrier properties. The pectinate pigmented cells arise during development from retinal pigment epithelial cells and subsequently lose barrier properties. These inverse transdifferentiation processes may be triggered by the peculiar microenvironment in the vitreous body. In addition, the question is discussed whether the avascularity of the avian retina may be due to the specific metabolic activity of the pecten.
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Affiliation(s)
- H Wolburg
- Institute of Pathology, University of Tübingen, Germany
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Nualart F, Godoy A, Reinicke K. Expression of the hexose transporters GLUT1 and GLUT2 during the early development of the human brain. Brain Res 1999; 824:97-104. [PMID: 10095047 DOI: 10.1016/s0006-8993(99)01078-1] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We used immunohistochemistry with anti-glucose transporter antibodies to document the presence of facilitative hexose transporters in the fetal human brain. GLUT1 is expressed in all regions of the fetal brain from ages 10 to 21 weeks. GLUT1 was present in the endothelial cells of the brain capillaries, the epithelial cells of the choroid plexus and neurons. High expression of GLUT2 was observed in the granular layer of the cerebellum in brains 21 weeks old, but GLUT2 immunoreactivity was absent at earlier stages. GLUT3 and GLUT4 immunoreactivities were absent at all stages studied. GLUT5 immunoreactivity was evident only in the cerebellar region of 21-week old fetal brains. We conclude that GLUT1 plays a fundamental role in early human brain development. The data also suggest that the cerebellum of the developing brain has the capacity to transport fructose, a substrate that has not been previously identified as a source of metabolic energy in the adult human brain.
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Affiliation(s)
- F Nualart
- Departamento de Histología y Embriología, Facultad de Ciencias Biológicas, Casilla 160-C, Universidad de Concepción, Concepción, Chile.
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Gupta A, Agarwal R, Shukla GS. Functional impairment of blood-brain barrier following pesticide exposure during early development in rats. Hum Exp Toxicol 1999; 18:174-9. [PMID: 10215108 DOI: 10.1177/096032719901800307] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
1. The effect of certain pesticides on the functional integrity of the developing blood-brain barrier (BBB) was studied following single and repeated exposure, and after subsequent withdrawal in rats. 2. Ten-day-old rat pups exposed orally to quinalphos (QP, organophosphate), cypermethrin (CM, pyrethroid) and lindane (LD, organochlorine) at a dose of 1/50th of LD50, showed a significant increase in the brain uptake index (BUI) for a micromolecular tracer, sodium fluorescein (SF), by 97, 37 and 72%, respectively, after 2 h. Residual increases in the BUI were found even after 3 days of the single treatment of QP (28%) and LD (23%). 3. Repeated exposure for 8 days (postnatal days (PND) 10-17) with QP, CM and LD increased the BBB permeability by 130, 80 and 50%, respectively. Recovery from these changes was complete in QP and LD-treated animals after 13 days (PND 18-30) of withdrawal. However, CM showed persistent effects that were normalized only after 43 days (PND 18-60) of withdrawal. 4. A single dose reduced to 1/100th of LD50 also increased BUI in 10-day-old rat pups following QP (20%) and CM (28%) exposure at 2 h. 5. An age-dependent effect of these pesticides was evident from the study showing higher magnitude of BUI changes in 10-day-old rats as compared to that in 15-day-old rats. Furthermore, adult rats did not show any effect on BBB permeability even at a higher dose (1/25th of LD50) of these pesticides given alone or in combination with piperonyl butoxide (600 mg/kg, i.p.) for 3 consecutive days. 6. This study showed that developing BBB is highly vulnerable to single or repeated exposure of certain pesticides. The observed persistent effects during brain development even after withdrawal of the treatment may produce some neurological dysfunction at later life as well.
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Affiliation(s)
- A Gupta
- Predictive Toxicology Research Group, Industrial Toxicology Research Centre, Lucknow, India
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46
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Saunders NR, Habgood MD, Dziegielewska KM. Barrier mechanisms in the brain, II. Immature brain. Clin Exp Pharmacol Physiol 1999; 26:85-91. [PMID: 10065326 DOI: 10.1046/j.1440-1681.1999.02987.x] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. It is widely believed that 'the' blood-brain barrier is immature in foetuses and newborns. 2. Much evidence in support of this belief is based on experiments that were unphysiological and likely to have disrupted fragile blood vessels of the developing brain. Some confusion about barrier development arises from insufficient recognition that the term 'blood-brain barrier' describes a complex series of mechanisms controlling the internal environment of the brain. 3. We present evidence showing that the brain develops within an environment that, particularly with respect to protein, is different from that of the rest of the body and that possesses a number of unique features not present in the adult. 4. Barriers to protein at blood-brain and blood-cerebrospinal fluid (CSF) interfaces (tight junctions) are present from very early in development; immunocytochemical and permeability data show that proteins are largely excluded from extracellular space in developing brain. 5. Cerebrospinal fluid in developing brain contains high concentrations of proteins largely derived from plasma. This protein is transferred from blood by an intracellular mechanism across the epithelial cells of the immature choroid plexus. Only a small proportion of choroid plexus cells is involved. The route is an intracellular system of tubulo-endoplasmic reticulum continuously connected across the epithelial cells only early in brain development. 6. High concentrations of proteins in CSF in developing brain are largely excluded from the brain's extracellular space by barriers at the internal and external CSF-brain interfaces. These consist of membrane specializations between surfaces of cells forming these interfaces (neuroependyma on the inner surface; radial glial end feet on the outer surface). In contrast with tight junctions present at the blood-brain and blood-CSF barriers, at the CSF-brain barriers of the immature brain, other junctional types are involved: strap junctions in the neuroependyma and a mixture of junctions at the outer CSF-brain barrier (plate junctions, strap junctions and wafer junctions). These barriers are not present in the adult. 7. Permeability to small lipid-insoluble molecules is greater in developing brain; more specific mechanisms, such as those involved in transfer of ions and amino acids, develop sequentially as the brain grows.
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Affiliation(s)
- N R Saunders
- Department of Anatomy and Physiology, University of Tasmania, Hobart, Australia.
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47
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Phillips DE, Krueger SK, Wall KA, Smoyer-Dearing LH, Sikora AK. The development of the blood-brain barrier in alcohol-exposed rats. Alcohol 1997; 14:333-43. [PMID: 9209548 DOI: 10.1016/s0741-8329(96)00180-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Circulating horseradish peroxidase (HRP) was used as a tracer to determine if the blood-brain barrier to protein was altered by dietary prenatal alcohol exposure. Animals were prepared for light microscopic visualization of HRP after HRP infusion on gestational days 16, 18, 20, 22 and postnatal day 4. There was no consistent evidence of HRP leakage through the BBB in the alcohol-exposed animals compared to control animals. Capillary endothelial cells and perivascular astrocytic endfeet were morphologically characterized by electron microscopy in rat optic nerve and cerebellum following dietary prenatal and postnatal ethanol exposure. Photomontages of optic nerve capillaries from G20 and P5 animals and cerebellar capillaries from P15 animals were examined for evidences of effects of alcohol on the development of the capillaries and adjacent astroglial endfeet. There was no consistent evidence of any alcohol-induced effect that could indicate a disruption of the vessel, the endothelial tight junctions, the perivascular glial limiting membranes, or the extent of vascular ensheathment by astrocytic endfeet.
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Affiliation(s)
- D E Phillips
- Biology Department, Montana State University, Bozeman 59717, USA.
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Kniesel U, Risau W, Wolburg H. Development of blood-brain barrier tight junctions in the rat cortex. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1996; 96:229-40. [PMID: 8922685 DOI: 10.1016/0165-3806(96)00117-4] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The structural equivalent of the blood-brain barrier are the complex tight junctions (TJs) between endothelial cells of brain capillaries. In this study, we have quantitatively investigated by the freeze-fracture technique the modulation of the fine structure of TJs in blood-brain barrier endothelial cells during development of the rat cerebral cortex. The complexity of the TJ network as defined by fractal dimension, the integrity of TJ strands and the degree of TJ particle association to the protoplasmic leaflet of the membrane bilayer in percent of total TJ length were evaluated at embryonic days (E) 13, 15, 18, postnatal day (P) 1 and adult. We observed that the overall complexity of the TJ network and P-face association of TJ particles are significantly increased between E18 and P1. The increase in both of these TJ parameters in combination with the completed particle insertion starting from E18 is likely to reflect the process of transition to the mature state of the blood-brain barrier, which is characterized by high complexity of TJs and predominance of P-face association of TJ particles and correlated tightly with previous physiological measurements, e.g. transendothelial electrical resistance. Two populations of TJs differing in TJ particle density were distinguishable at E15 and E18, which indicates a non-linear asynchronous mechanism of TJ assembly. At E13, particle-free membrane specializations arranged in a TJ-like pattern strongly resembled TJ specific grooves and ridges. Similar results were obtained from cultures of brain endothelial cells in the presence of low calcium conditions, which suggests the involvement of the cadherin/catenin complex in TJ regulation. The particle-free 'TJ precursors' strongly indicate an established TJ associated cytoskeletal network before the TJ particles are present in their intra-junctional location.
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Affiliation(s)
- U Kniesel
- Max-Planck-Institut für Physiologische, W.G. Kerckhoff-Institut, Bad Nauheim, Germany
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Kiernan JA. Vascular permeability in the peripheral autonomic and somatic nervous systems: controversial aspects and comparisons with the blood-brain barrier. Microsc Res Tech 1996; 35:122-36. [PMID: 8923447 DOI: 10.1002/(sici)1097-0029(19961001)35:2<122::aid-jemt3>3.0.co;2-s] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Endothelium, choroidal epithelium, and arachnoid exclude plasma proteins from most parts of the mammalian central nervous system (CNS). Nerve roots, in contrast, have permeable capillaries and permeable pia-arachnoid sheaths. Diffusion of plasma proteins into the cerebrospinal fluid is probably prevented by slow bulk flow along a pressure gradient from the subarachnoid space into the veins of the roots. In nerves, the perineurium prevents diffusion of proteins from the epineurium into the endoneurium. Capillaries within fascicles are permeable to macromolecules, though less so than the microvessels of roots and ganglia. Endoneurial vascular permeability is lowest in rats and mice, but even in these species albumin is normally present in the extracellular spaces around the nerve fibers. The so-called blood-nerve barrier is not equivalent to the blood-brain barrier. Capillaries in sensory and sympathetic ganglia are fully permeable to macromolecules, and extravasated protein is in contact with neuronal cell bodies and neurites. An impenetrable perineurium surrounds each ganglion, but serves no obvious purpose when the vessels inside are as permeable as those outside. The enteric nervous system lacks a perineurium, and the neurons in its avascular ganglia and tracts are exposed to extracellular fluid formed by permeable vessels in adjacent tissues of the gut. The reasons for excluding macromolecules from some parts of the nervous system are obscure. Carrier-mediated transport, which maintains a constant supply of ions, glucose, and other metabolites to cells in the CNS, would be impossible if larger molecules could diffuse freely. Presumably the metabolic needs of ganglia are adequately met by exchange vessels similar to those of nonnervous tissues. Most of the CNS is protected from exogenous toxic substances that bind to plasma proteins. Peripheral neurons and glial cells are damaged by some such substances because of the lack of blood-tissue barriers.
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Affiliation(s)
- J A Kiernan
- Department of Anatomy, University of Western Ontario, London, Canada
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