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Fritzen L, Wienken K, Wagner L, Kurtyka M, Vogel K, Körbelin J, Weggen S, Fricker G, Pietrzik CU. Truncated mini LRP1 transports cargo from luminal to basolateral side across the blood brain barrier. Fluids Barriers CNS 2024; 21:74. [PMID: 39289695 PMCID: PMC11409491 DOI: 10.1186/s12987-024-00573-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Accepted: 09/02/2024] [Indexed: 09/19/2024] Open
Abstract
BACKGROUND The most crucial area to focus on when thinking of novel pathways for drug delivery into the CNS is the blood brain barrier (BBB). A number of nanoparticulate formulations have been shown in earlier research to target receptors at the BBB and transport therapeutics into the CNS. However, no mechanism for CNS entrance and movement throughout the CNS parenchyma has been proposed yet. Here, the truncated mini low-density lipoprotein receptor-related protein 1 mLRP1_DIV* was presented as blood to brain transport carrier, exemplified by antibodies and immunoliposomes using a systematic approach to screen the receptor and its ligands' route across endothelial cells in vitro. METHODS The use of mLRP1_DIV* as liposomal carrier into the CNS was validated based on internalization and transport assays across an in vitro model of the BBB using hcMEC/D3 and bEnd.3 cells. Trafficking routes of mLRP1_DIV* and corresponding cargo across endothelial cells were analyzed using immunofluorescence. Modulation of γ-secretase activity by immunoliposomes loaded with the γ-secretase modulator BB25 was investigated in co-cultures of bEnd.3 mLRP1_DIV* cells and CHO cells overexpressing human amyloid precursor protein (APP) and presenilin 1 (PSEN1). RESULTS We showed that while expressed in vitro, mLRP1_DIV* transports both, antibodies and functionalized immunoliposomes from luminal to basolateral side across an in vitro model of the BBB, followed by their mLRP1_DIV* dependent release of the cargo. Importantly, functionalized liposomes loaded with the γ-secretase modulator BB25 were demonstrated to effectively reduce toxic Aß42 peptide levels after mLRP1_DIV* mediated transport across a co-cultured endothelial monolayer. CONCLUSION Together, the data strongly suggest mLRP1_DIV* as a promising tool for drug delivery into the CNS, as it allows a straight transport of cargo from luminal to abluminal side across an endothelial monolayer and it's release into brain parenchyma in vitro, where it exhibits its intended therapeutic effect.
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Affiliation(s)
- Laura Fritzen
- Molecular Neurodegeneration, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University of Mainz, Duesbergweg 6, 55099, Mainz, Germany.
| | - Katharina Wienken
- Institute for Pharmacy and Molecular Biotechnology, University Heidelberg, Heidelberg, Germany
| | - Lelia Wagner
- Institute for Pharmacy and Molecular Biotechnology, University Heidelberg, Heidelberg, Germany
| | - Magdalena Kurtyka
- Molecular Neurodegeneration, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University of Mainz, Duesbergweg 6, 55099, Mainz, Germany
| | - Katharina Vogel
- Department of Neuropathology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Jakob Körbelin
- Department for Oncology and Hematology, University Medical Center Hamburg-Eppendorf, Hubertus Wald Cancer Center, Hamburg, Germany
| | - Sascha Weggen
- Department of Neuropathology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Gert Fricker
- Institute for Pharmacy and Molecular Biotechnology, University Heidelberg, Heidelberg, Germany
| | - Claus U Pietrzik
- Molecular Neurodegeneration, Institute for Pathobiochemistry, University Medical Center of the Johannes Gutenberg-University of Mainz, Duesbergweg 6, 55099, Mainz, Germany.
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Chen T, Dai Y, Hu C, Lin Z, Wang S, Yang J, Zeng L, Li S, Li W. Cellular and molecular mechanisms of the blood-brain barrier dysfunction in neurodegenerative diseases. Fluids Barriers CNS 2024; 21:60. [PMID: 39030617 PMCID: PMC11264766 DOI: 10.1186/s12987-024-00557-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Accepted: 06/20/2024] [Indexed: 07/21/2024] Open
Abstract
BACKGROUND Maintaining the structural and functional integrity of the blood-brain barrier (BBB) is vital for neuronal equilibrium and optimal brain function. Disruptions to BBB performance are implicated in the pathology of neurodegenerative diseases. MAIN BODY Early indicators of multiple neurodegenerative disorders in humans and animal models include impaired BBB stability, regional cerebral blood flow shortfalls, and vascular inflammation associated with BBB dysfunction. Understanding the cellular and molecular mechanisms of BBB dysfunction in brain disorders is crucial for elucidating the sustenance of neural computations under pathological conditions and for developing treatments for these diseases. This paper initially explores the cellular and molecular definition of the BBB, along with the signaling pathways regulating BBB stability, cerebral blood flow, and vascular inflammation. Subsequently, we review current insights into BBB dynamics in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. The paper concludes by proposing a unified mechanism whereby BBB dysfunction contributes to neurodegenerative disorders, highlights potential BBB-focused therapeutic strategies and targets, and outlines lessons learned and future research directions. CONCLUSIONS BBB breakdown significantly impacts the development and progression of neurodegenerative diseases, and unraveling the cellular and molecular mechanisms underlying BBB dysfunction is vital to elucidate how neural computations are sustained under pathological conditions and to devise therapeutic approaches.
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Affiliation(s)
- Tongli Chen
- School of Medicine, Hangzhou City University, Hangzhou, China
| | - Yan Dai
- School of Medicine, Hangzhou City University, Hangzhou, China
| | - Chenghao Hu
- School of Medicine, Hangzhou City University, Hangzhou, China
| | - Zihao Lin
- School of Medicine, Hangzhou City University, Hangzhou, China
| | - Shengzhe Wang
- School of Medicine, Hangzhou City University, Hangzhou, China
| | - Jing Yang
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, China.
- Institute of Brain and Cognitive Science, Hangzhou City University, Hangzhou, China.
| | - Linghui Zeng
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, China.
- Institute of Brain and Cognitive Science, Hangzhou City University, Hangzhou, China.
| | - Shanshan Li
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, China.
- Institute of Brain and Cognitive Science, Hangzhou City University, Hangzhou, China.
| | - Weiyun Li
- Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, China.
- Institute of Brain and Cognitive Science, Hangzhou City University, Hangzhou, China.
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3
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Li F, Ma C, Lei S, Pan Y, Lin L, Pan C, Li Q, Geng F, Min D, Tang X. Gingipains may be one of the key virulence factors of Porphyromonas gingivalis to impair cognition and enhance blood-brain barrier permeability: An animal study. J Clin Periodontol 2024; 51:818-839. [PMID: 38414291 DOI: 10.1111/jcpe.13966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 01/24/2024] [Accepted: 02/08/2024] [Indexed: 02/29/2024]
Abstract
AIM Blood-brain barrier (BBB) disorder is one of the early findings in cognitive impairments. We have recently found that Porphyromonas gingivalis bacteraemia can cause cognitive impairment and increased BBB permeability. This study aimed to find out the possible key virulence factors of P. gingivalis contributing to the pathological process. MATERIALS AND METHODS C57/BL6 mice were infected with P. gingivalis or gingipains or P. gingivalis lipopolysaccharide (P. gingivalis LPS group) by tail vein injection for 8 weeks. The cognitive behaviour changes in mice, the histopathological changes in the hippocampus and cerebral cortex, the alternations of BBB permeability, and the changes in Mfsd2a and Cav-1 levels were measured. The mechanisms of Ddx3x-induced regulation on Mfsd2a by arginine-specific gingipain A (RgpA) in BMECs were explored. RESULTS P. gingivalis and gingipains significantly promoted mice cognitive impairment, pathological changes in the hippocampus and cerebral cortex, increased BBB permeability, inhibited Mfsd2a expression and up-regulated Cav-1 expression. After RgpA stimulation, the permeability of the BBB model in vitro increased, and the Ddx3x/Mfsd2a/Cav-1 regulatory axis was activated. CONCLUSIONS Gingipains may be one of the key virulence factors of P. gingivalis to impair cognition and enhance BBB permeability by the Ddx3x/Mfsd2a/Cav-1 axis.
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Affiliation(s)
- Fulong Li
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
- Center of Implantology, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Chunliang Ma
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Shuang Lei
- Department of Pediatric Dentistry, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Yaping Pan
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Li Lin
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Chunling Pan
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Qian Li
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Fengxue Geng
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Dongyu Min
- Traditional Chinese Medicine Experimental Center, Affiliated Hospital of Liaoning University of Traditional Chinese Medicine, Shenyang, China
- Key Laboratory of Ministry of Education for TCM Viscera State Theory and Applications, Liaoning University of Traditional Chinese Medicine, Shenyang, China
| | - Xiaolin Tang
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
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Hazell AS. Stem Cell Therapy and Thiamine Deficiency-Induced Brain Damage. Neurochem Res 2024; 49:1450-1467. [PMID: 38720090 DOI: 10.1007/s11064-024-04137-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 01/18/2024] [Accepted: 03/15/2024] [Indexed: 05/21/2024]
Abstract
Wernicke's encephalopathy (WE) is a major central nervous system disorder resulting from thiamine deficiency (TD) in which a number of brain regions can develop serious damage including the thalamus and inferior colliculus. Despite decades of research into the pathophysiology of TD and potential therapeutic interventions, little progress has been made regarding effective treatment following the development of brain lesions and its associated cognitive issues. Recent developments in our understanding of stem cells suggest they are capable of repairing damage and improving function in different maladys. This article puts forward the case for the potential use of stem cell treatment as a therapeutic strategy in WE by first examining the effects of TD on brain functional integrity and its consequences. The second half of the paper will address the future benefits of treating TD with these cells by focusing on their nature and their potential to effectively treat neurodegenerative diseases that share some overlapping pathophysiological features with TD. At the same time, some of the obstacles these cells will have to overcome in order to become a viable therapeutic strategy for treating this potentially life-threatening illness in humans will be highlighted.
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Affiliation(s)
- Alan S Hazell
- Department of Medicine, University of Montreal, 2335 Bennett Avenue, Montreal, QC, H1V 2T6, Canada.
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5
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Calado M, Ferreira R, Pires D, Santos-Costa Q, Anes E, Brites D, Azevedo-Pereira JM. Unravelling the triad of neuroinvasion, neurodissemination, and neuroinflammation of human immunodeficiency virus type 1 in the central nervous system. Rev Med Virol 2024; 34:e2534. [PMID: 38588024 DOI: 10.1002/rmv.2534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/05/2024] [Accepted: 03/28/2024] [Indexed: 04/10/2024]
Abstract
Since the identification of human immunodeficiency virus type 1 (HIV-1) in 1983, many improvements have been made to control viral replication in the peripheral blood and to treat opportunistic infections. This has increased life expectancy but also the incidence of age-related central nervous system (CNS) disorders and HIV-associated neurodegeneration/neurocognitive impairment and depression collectively referred to as HIV-associated neurocognitive disorders (HAND). HAND encompasses a spectrum of different clinical presentations ranging from milder forms such as asymptomatic neurocognitive impairment or mild neurocognitive disorder to a severe HIV-associated dementia (HAD). Although control of viral replication and suppression of plasma viral load with combination antiretroviral therapy has reduced the incidence of HAD, it has not reversed milder forms of HAND. The objective of this review, is to describe the mechanisms by which HIV-1 invades and disseminates in the CNS, a crucial event leading to HAND. The review will present the evidence that underlies the relationship between HIV infection and HAND. Additionally, recent findings explaining the role of neuroinflammation in the pathogenesis of HAND will be discussed, along with prospects for treatment and control.
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Affiliation(s)
- Marta Calado
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Rita Ferreira
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - David Pires
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- Center for Interdisciplinary Research in Health, Católica Medical School, Universidade Católica Portuguesa, Estrada Octávio Pato, Rio de Mouro, Portugal
| | - Quirina Santos-Costa
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Elsa Anes
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Dora Brites
- Neuroinflammation, Signaling and Neuroregeneration Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - José Miguel Azevedo-Pereira
- Host-Pathogen Interactions Unit, Research Institute for Medicines, iMed-ULisboa, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
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6
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Wu D, Chen Q, Chen X, Han F, Chen Z, Wang Y. The blood-brain barrier: structure, regulation, and drug delivery. Signal Transduct Target Ther 2023; 8:217. [PMID: 37231000 PMCID: PMC10212980 DOI: 10.1038/s41392-023-01481-w] [Citation(s) in RCA: 181] [Impact Index Per Article: 181.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 04/19/2023] [Accepted: 04/27/2023] [Indexed: 05/27/2023] Open
Abstract
Blood-brain barrier (BBB) is a natural protective membrane that prevents central nervous system (CNS) from toxins and pathogens in blood. However, the presence of BBB complicates the pharmacotherapy for CNS disorders as the most chemical drugs and biopharmaceuticals have been impeded to enter the brain. Insufficient drug delivery into the brain leads to low therapeutic efficacy as well as aggravated side effects due to the accumulation in other organs and tissues. Recent breakthrough in materials science and nanotechnology provides a library of advanced materials with customized structure and property serving as a powerful toolkit for targeted drug delivery. In-depth research in the field of anatomical and pathological study on brain and BBB further facilitates the development of brain-targeted strategies for enhanced BBB crossing. In this review, the physiological structure and different cells contributing to this barrier are summarized. Various emerging strategies for permeability regulation and BBB crossing including passive transcytosis, intranasal administration, ligands conjugation, membrane coating, stimuli-triggered BBB disruption, and other strategies to overcome BBB obstacle are highlighted. Versatile drug delivery systems ranging from organic, inorganic, and biologics-derived materials with their synthesis procedures and unique physio-chemical properties are summarized and analyzed. This review aims to provide an up-to-date and comprehensive guideline for researchers in diverse fields, offering perspectives on further development of brain-targeted drug delivery system.
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Affiliation(s)
- Di Wu
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, 310053, Hangzhou, China.
- Zhejiang Rehabilitation Medical Center, The Third Affiliated Hospital of Zhejiang Chinese Medical University, 310053, Hangzhou, China.
| | - Qi Chen
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, 310053, Hangzhou, China
| | - Xiaojie Chen
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, 310053, Hangzhou, China
| | - Feng Han
- Key Laboratory of Cardiovascular & Cerebrovascular Medicine, Drug Target and Drug Discovery Center, School of Pharmacy, Nanjing Medical University, Nanjing, China
| | - Zhong Chen
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, 310053, Hangzhou, China.
| | - Yi Wang
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, 310053, Hangzhou, China.
- Zhejiang Rehabilitation Medical Center, The Third Affiliated Hospital of Zhejiang Chinese Medical University, 310053, Hangzhou, China.
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Gullotta GS, Costantino G, Sortino MA, Spampinato SF. Microglia and the Blood-Brain Barrier: An External Player in Acute and Chronic Neuroinflammatory Conditions. Int J Mol Sci 2023; 24:ijms24119144. [PMID: 37298096 DOI: 10.3390/ijms24119144] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 05/18/2023] [Accepted: 05/20/2023] [Indexed: 06/12/2023] Open
Abstract
Microglia are the resident immune cells of the central nervous system that guarantee immune surveillance and exert also a modulating role on neuronal synaptic development and function. Upon injury, microglia get activated and modify their morphology acquiring an ameboid phenotype and pro- or anti-inflammatory features. The active role of microglia in blood-brain barrier (BBB) function and their interaction with different cellular components of the BBB-endothelial cells, astrocytes and pericytes-are described. Here, we report the specific crosstalk of microglia with all the BBB cell types focusing in particular on the involvement of microglia in the modulation of BBB function in neuroinflammatory conditions that occur in conjunction with an acute event, such as a stroke, or in a slow neurodegenerative disease, such as Alzheimer's disease. The potential of microglia to exert a dual role, either protective or detrimental, depending on disease stages and environmental conditioning factors is also discussed.
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Affiliation(s)
- Giorgia Serena Gullotta
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
| | - Giuseppe Costantino
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
- Ph.D. Program in Neuroscience and Education, DISTUM, University of Foggia, 71121 Foggia, Italy
| | - Maria Angela Sortino
- Department of Biomedical and Biotechnological Sciences, University of Catania, 95123 Catania, Italy
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8
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Chamarthy S, Mekala JR. Functional importance of glucose transporters and chromatin epigenetic factors in Glioblastoma Multiforme (GBM): possible therapeutics. Metab Brain Dis 2023; 38:1441-1469. [PMID: 37093461 DOI: 10.1007/s11011-023-01207-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/22/2023] [Indexed: 04/25/2023]
Abstract
Glioblastoma Multiforme (GBM) is an aggressive brain cancer affecting glial cells and is chemo- and radio-resistant. Glucose is considered the most vital energy source for cancer cell proliferation. During metabolism, hexose molecules will be transported into the cells via transmembrane proteins known as glucose transporter (GLUT). Among them, GLUT-1 and GLUT-3 play pivotal roles in glucose transport in GBM. Knockdown studies have established the role of GLUT-1, and GLUT-3 mediated glucose transport in GBM cells, providing insight into GLUT-mediated cancer signaling and cancer aggressiveness. This review focussed on the vital role of GLUT-1 and GLUT-3 proteins, which regulate glucose transport. Recent studies have identified the role of GLUT inhibitors in effective cancer prevention. Several of them are in clinical trials. Understanding and functional approaches towards glucose-mediated cell metabolism and chromatin epigenetics will provide valuable insights into the mechanism of cancer aggressiveness, cancer stemness, and chemo-resistance in Glioblastoma Multiforme (GBM). This review summarizes the role of GLUT inhibitors, micro-RNAs, and long non-coding RNAs that aid in inhibiting glucose uptake by the GBM cells and other cancer cells leading to the identification of potential therapeutic, prognostic as well as diagnostic markers. Furthermore, the involvement of epigenetic factors, such as microRNAs, in regulating glycolytic genes was demonstrated.
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Affiliation(s)
- Sahiti Chamarthy
- Department of Biotechnology, Koneru Lakshmaiah Education Foundation (KLEF), Green Fields, Vaddeswaram, Guntur, Andhra Pradesh, 522302, India
| | - Janaki Ramaiah Mekala
- Department of Biotechnology, Koneru Lakshmaiah Education Foundation (KLEF), Green Fields, Vaddeswaram, Guntur, Andhra Pradesh, 522302, India.
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9
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Archie SR, Al Shoyaib A, Cucullo L. Blood-Brain Barrier Dysfunction in CNS Disorders and Putative Therapeutic Targets: An Overview. Pharmaceutics 2021; 13:pharmaceutics13111779. [PMID: 34834200 PMCID: PMC8622070 DOI: 10.3390/pharmaceutics13111779] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/15/2021] [Accepted: 10/20/2021] [Indexed: 01/22/2023] Open
Abstract
The blood-brain barrier (BBB) is a fundamental component of the central nervous system (CNS). Its functional and structural integrity is vital to maintain the homeostasis of the brain microenvironment by controlling the passage of substances and regulating the trafficking of immune cells between the blood and the brain. The BBB is primarily composed of highly specialized microvascular endothelial cells. These cells’ special features and physiological properties are acquired and maintained through the concerted effort of hemodynamic and cellular cues from the surrounding environment. This complex multicellular system, comprising endothelial cells, astrocytes, pericytes, and neurons, is known as the neurovascular unit (NVU). The BBB strictly controls the transport of nutrients and metabolites into brain parenchyma through a tightly regulated transport system while limiting the access of potentially harmful substances via efflux transcytosis and metabolic mechanisms. Not surprisingly, a disruption of the BBB has been associated with the onset and/or progression of major neurological disorders. Although the association between disease and BBB disruption is clear, its nature is not always evident, specifically with regard to whether an impaired BBB function results from the pathological condition or whether the BBB damage is the primary pathogenic factor prodromal to the onset of the disease. In either case, repairing the barrier could be a viable option for treating and/or reducing the effects of CNS disorders. In this review, we describe the fundamental structure and function of the BBB in both healthy and altered/diseased conditions. Additionally, we provide an overview of the potential therapeutic targets that could be leveraged to restore the integrity of the BBB concomitant to the treatment of these brain disorders.
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Affiliation(s)
- Sabrina Rahman Archie
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; (S.R.A.); (A.A.S.)
| | - Abdullah Al Shoyaib
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; (S.R.A.); (A.A.S.)
| | - Luca Cucullo
- Department of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Rochester, MI 48309, USA
- Correspondence: ; Tel.: +1-248-370-3884; Fax: +1-248-370-4060
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10
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Surface Functionalization of PLGA Nanoparticles to Increase Transport across the BBB for Alzheimer’s Disease. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11094305] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alzheimer’s disease (AD) is a chronic neurodegenerative disorder that accounts for about 60% of all diagnosed cases of dementia worldwide. Although there are currently several drugs marketed for its treatment, none are capable of slowing down or stopping the progression of AD. The role of the blood-brain barrier (BBB) plays a key role in the design of a successful treatment for this neurodegenerative disease. Nanosized particles have been proposed as suitable drug delivery systems to overcome BBB with the purpose of increasing bioavailability of drugs in the brain. Biodegradable poly (lactic-co-glycolic acid) nanoparticles (PLGA-NPs) have been particularly regarded as promising drug delivery systems as they can be surface-tailored with functionalized molecules for site-specific targeting. In this review, a thorough discussion about the most recent functionalization strategies based on PLGA-NPs for AD and their mechanisms of action is provided, together with a description of AD pathogenesis and the role of the BBB in brain targeting.
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11
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Lu TM, Barcia Durán JG, Houghton S, Rafii S, Redmond D, Lis R. Human Induced Pluripotent Stem Cell-Derived Brain Endothelial Cells: Current Controversies. Front Physiol 2021; 12:642812. [PMID: 33868008 PMCID: PMC8044318 DOI: 10.3389/fphys.2021.642812] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/08/2021] [Indexed: 12/12/2022] Open
Abstract
Brain microvascular endothelial cells (BMECs) possess unique properties that are crucial for many functions of the blood-brain-barrier (BBB) including maintenance of brain homeostasis and regulation of interactions between the brain and immune system. The generation of a pure population of putative brain microvascular endothelial cells from human pluripotent stem cell sources (iBMECs) has been described to meet the need for reliable and reproducible brain endothelial cells in vitro. Human pluripotent stem cells (hPSCs), embryonic or induced, can be differentiated into large quantities of specialized cells in order to study development and model disease. These hPSC-derived iBMECs display endothelial-like properties, such as tube formation and low-density lipoprotein uptake, high transendothelial electrical resistance (TEER), and barrier-like efflux transporter activities. Over time, the de novo generation of an organotypic endothelial cell from hPSCs has aroused controversies. This perspective article highlights the developments made in the field of hPSC derived brain endothelial cells as well as where experimental data are lacking, and what concerns have emerged since their initial description.
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Affiliation(s)
- Tyler M Lu
- Division of Regenerative Medicine, Department of Medicine, Ansary Stem Cell Institute, Weill Cornell Medicine, New York, NY, United States.,Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY, United States
| | - José Gabriel Barcia Durán
- Division of Regenerative Medicine, Department of Medicine, Ansary Stem Cell Institute, Weill Cornell Medicine, New York, NY, United States
| | - Sean Houghton
- Division of Regenerative Medicine, Department of Medicine, Ansary Stem Cell Institute, Weill Cornell Medicine, New York, NY, United States
| | - Shahin Rafii
- Division of Regenerative Medicine, Department of Medicine, Ansary Stem Cell Institute, Weill Cornell Medicine, New York, NY, United States
| | - David Redmond
- Division of Regenerative Medicine, Department of Medicine, Ansary Stem Cell Institute, Weill Cornell Medicine, New York, NY, United States
| | - Raphaël Lis
- Division of Regenerative Medicine, Department of Medicine, Ansary Stem Cell Institute, Weill Cornell Medicine, New York, NY, United States.,Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY, United States
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12
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Hazell AS, Butterworth RF. Region-selective permeability of the blood-brain barrier to α-aminoisobutyric acid during thiamine deficiency and following its reversal. Metab Brain Dis 2021; 36:239-246. [PMID: 33245475 DOI: 10.1007/s11011-020-00644-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 11/03/2020] [Indexed: 11/30/2022]
Abstract
Thiamine deficiency (TD) results in focal lesions in several regions of the rat brain including the thalamus and inferior colliculus. Since alterations in blood-brain barrier (BBB) integrity may play a role in this damage, we have examined the influence of TD on the unidirectional blood-to-brain transfer constant (Ki) of the low molecular weight species α-aminoisobutyric acid (AIB) in vulnerable and non-vulnerable brain regions at different stages during progression of the disorder, and following its reversal with thiamine. Analysis of the regional distribution of Ki values showed early (day 10) increased transfer of [14C]-AIB across the BBB in the vulnerable medial thalamus as well as the non-vulnerable caudate and hippocampus. At the acute symptomatic stage (day 14), more widespread BBB permeability changes were detected in most areas including the lateral thalamus, inferior colliculus, and non-vulnerable cerebellum and pons. Twenty-four hours following thiamine replenishment, a heterogeneous pattern of increased BBB permeability was observed in which many structures maintained increased uptake of [14C]-AIB. No increase in the [3H]-dextran space, a marker of intravascular volume, was detected in brain regions during the progress of TD, suggesting that BBB permeability to this large tracer was unaffected. These results indicate that BBB opening i) occurs early during TD, ii) is not restricted to vulnerable areas of the brain, iii) is progressive, iv) persists for at least 24 h following treatment with thiamine, and v) is likely selective in nature, depending on the molecular species being transported.
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Affiliation(s)
- Alan S Hazell
- Department of Medicine, University of Montreal, Montreal, Quebec, Canada.
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13
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Ahishali B, Kaya M. Evaluation of Blood-Brain Barrier Integrity Using Vascular Permeability Markers: Evans Blue, Sodium Fluorescein, Albumin-Alexa Fluor Conjugates, and Horseradish Peroxidase. Methods Mol Biol 2021; 2367:87-103. [PMID: 32785841 DOI: 10.1007/7651_2020_316] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The blood-brain barrier (BBB) constituted by endothelial cells of brain microvessels is a dynamic interface, which controls and regulates the transport of various substances including peptides, proteins, ions, vitamins, hormones, and immune cells from the circulation into the brain parenchyma. Certain diseases/disorders such as Alzheimer's disease, sepsis, and hypertension can lead to varying degrees of BBB disruption. Moreover, impairment of BBB integrity has been implicated in the pathogenesis of various neurodegenerative diseases like epilepsy. In attempts to explore the wide spectrum of pathophysiologic mechanisms of these diseases/disorders, a variety of experimental insults targeted to the BBB integrity in vitro in cell culture models and in vivo in laboratory animals have been shown to alter BBB permeability causing enhanced transport of certain tracers such as sodium fluorescein, cadaverine-Alexa fluor, horseradish peroxidase, FITC-dextran, albumin-Alexa fluor conjugates, and Evans blue dye across the barrier. The permeability changes in barrier-type endothelial cells can be assessed by intravascular infusion of exogenous tracers and subsequent detection of the extravasated tracer in the brain tissue, which enable functional and structural analysis of BBB integrity. In this chapter, we aimed to highlight the current knowledge on the use of four most commonly performed tracers, namely, Evans blue, sodium fluorescein, albumin-Alexa fluor conjugates, and horseradish peroxidase. The experimental methodologies that we use in our laboratory for the detection of these tracers by macroscopy, spectrophotometry, spectrophotofluorometry, confocal laser scanning microscopy, and electron microscopy are also discussed. Tracing studies at the morphological level are mainly aimed at the identification of the tracers both in the barrier-related cells and brain parenchyma. In addition, BBB permeability to the tracers can be quantified using spectrophotometric and spectrophotofluorometric assays and image analysis by confocal laser scanning microscopy and electron microscopy. The results of our studies conducted under various experimental settings using the mentioned tracers indicate that barrier-type endothelial cells in brain microvessels orchestrate the paracellular and/or transcellular trafficking of substances across BBB. These efforts may not only contribute to designing approaches for the management of diseases/disorders associated with BBB breakdown but may also provide new insights for developing novel brain drug delivery strategies.
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Affiliation(s)
- Bulent Ahishali
- Department of Histology and Embryology, Koç University School of Medicine, Istanbul, Turkey
| | - Mehmet Kaya
- Department of Physiology, Koç University School of Medicine, Istanbul, Turkey.
- Koç University Research Center for Translational Medicine, Istanbul, Turkey.
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Viscusi ER, Viscusi AR. Blood-brain barrier: mechanisms governing permeability and interaction with peripherally acting μ-opioid receptor antagonists. Reg Anesth Pain Med 2020; 45:688-695. [PMID: 32723840 PMCID: PMC7476292 DOI: 10.1136/rapm-2020-101403] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/18/2020] [Accepted: 05/21/2020] [Indexed: 12/13/2022]
Abstract
The blood-brain barrier (BBB) describes the unique properties of endothelial cells (ECs) that line the central nervous system (CNS) microvasculature. The BBB supports CNS homeostasis via EC-associated transport of ions, nutrients, proteins and waste products between the brain and blood. These transport mechanisms also serve as physiological barriers to pathogens, toxins and xenobiotics to prevent them from contacting neural tissue. The mechanisms that govern BBB permeability pose a challenge to drug design for CNS disorders, including pain, but can be exploited to limit the effects of a drug to the periphery, as in the design of the peripherally acting μ-opioid receptor antagonists (PAMORAs) used to treat opioid-induced constipation. Here, we describe BBB physiology, drug properties that affect BBB penetrance and how data from randomized clinical trials of PAMORAs improve our understanding of BBB permeability.
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Affiliation(s)
- Eugene R Viscusi
- Department of Anesthesiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Andrew R Viscusi
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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15
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Zhang L, Wang H, Zhou X, Mao L, Ding K, Hu Z. Role of mitochondrial calcium uniporter-mediated Ca 2+ and iron accumulation in traumatic brain injury. J Cell Mol Med 2019; 23:2995-3009. [PMID: 30756474 PMCID: PMC6433723 DOI: 10.1111/jcmm.14206] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 12/28/2018] [Accepted: 01/16/2019] [Indexed: 12/17/2022] Open
Abstract
Previous studies have suggested that the cellular Ca2+ and iron homeostasis, which can be regulated by mitochondrial calcium uniporter (MCU), is associated with oxidative stress, apoptosis and many neurological diseases. However, little is known about the role of MCU‐mediated Ca2+ and iron accumulation in traumatic brain injury (TBI). Under physiological conditions, MCU can be inhibited by ruthenium red (RR) and activated by spermine (Sper). In the present study, we used RR and Sper to reveal the role of MCU in mouse and neuron TBI models. Our results suggested that the Ca2+ and iron concentrations were obviously increased after TBI. In addition, TBI models showed a significant generation of reactive oxygen species (ROS), decrease in adenosine triphosphate (ATP), deformation of mitochondria, up‐regulation of deoxyribonucleic acid (DNA) damage and increase in apoptosis. Blockage of MCU by RR prevented Ca2+ and iron accumulation, abated the level of oxidative stress, improved the energy supply, stabilized mitochondria, reduced DNA damage and decreased apoptosis both in vivo and in vitro. Interestingly, Sper did not increase cellular Ca2+ and iron concentrations, but suppressed the Ca2+ and iron accumulation to benefit the mice in vivo. However, Sper had no significant impact on TBI in vitro. Taken together, our data demonstrated for the first time that blockage of MCU‐mediated Ca2+ and iron accumulation was essential for TBI. These findings indicated that MCU could be a novel therapeutic target for treating TBI.
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Affiliation(s)
- Li Zhang
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu Province, China
| | - Handong Wang
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu Province, China
| | - Xiaoming Zhou
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu Province, China
| | - Lei Mao
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu Province, China
| | - Ke Ding
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu Province, China
| | - Zhigang Hu
- Department of Neurosurgery, Jinling Hospital, School of Medicine, Nanjing University, Nanjing, Jiangsu Province, China
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16
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Abstract
The blood-brain barrier (BBB) plays a vital role in the maintenance of brain homeostasis. It strictly restricts the passage of molecules from the brain vasculature into the brain via its high transendothelial electrical resistance and low paracellular and transcellular permeability. Specialized brain endothelial cells, astrocytes, pericytes, neurons, and microglia contribute synergistically to the functional properties of the BBB. Because of its complexity and relative inaccessibility, BBB research is fraught with difficulties. Most studies rely on animal or cell culture models, which are not able to fully recapitulate the properties of the human BBB. The recent development of three-dimensional (3D) microfluidic models of the BBB could address this issue. This chapter aims to provide an overview of the recent advances in modeling the BBB on microdevices, and illustrate important considerations for the design of such models. In addition, protocols for the fabrication of a 3D BBB microfluidic chip and BBB assessment experiments, including immunocytochemistry for analyzing cell morphology and protein marker expression, permeability assay, and calcium imaging for studying neuronal function as a measure of BBB integrity, are presented here. It is envisioned that continued advancements in microtechnology can lead to the creation of realistic in vivo-like BBB-on-chip models.
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Affiliation(s)
- Eunice Chin
- Neuroscience Academic Clinical Programme, Duke-NUS Medical School, Singapore
| | - Eyleen Goh
- Neuroscience Academic Clinical Programme, Duke-NUS Medical School, Singapore; Department of Research, National Neuroscience Institute, Singapore.
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17
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Coronado-Velázquez D, Betanzos A, Serrano-Luna J, Shibayama M. An In Vitro Model of the Blood-Brain Barrier: Naegleria fowleri Affects the Tight Junction Proteins and Activates the Microvascular Endothelial Cells. J Eukaryot Microbiol 2018; 65:804-819. [PMID: 29655298 DOI: 10.1111/jeu.12522] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/05/2018] [Accepted: 03/28/2018] [Indexed: 02/06/2023]
Abstract
Naegleria fowleri causes a fatal disease known as primary amoebic meningoencephalitis. This condition is characterized by an acute inflammation that originates from the free passage of peripheral blood cells to the central nervous system through the alteration of the blood-brain barrier. In this work, we established models of the infection in rats and in a primary culture of endothelial cells from rat brains with the aim of evaluating the activation and the alterations of these cells by N. fowleri. We proved that the rat develops the infection similar to the mouse model. We also found that amoebic cysteine proteases produced by the trophozoites and the conditioned medium induced cytopathic effect in the endothelial cells. In addition, N. fowleri can decrease the transendothelial electrical resistance by triggering the destabilization of the tight junction proteins claudin-5, occludin, and ZO-1 in a time-dependent manner. Furthermore, N. fowleri induced the expression of VCAM-1 and ICAM-1 and the production of IL-8, IL-1β, TNF-α, and IL-6 as well as nitric oxide. We conclude that N. fowleri damaged the blood-brain barrier model by disrupting the intercellular junctions and induced the presence of inflammatory mediators by allowing the access of inflammatory cells to the olfactory bulbs.
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Affiliation(s)
- Daniel Coronado-Velázquez
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies of the National Polytechnic Institute, Av. IPN 2508, Mexico City, 07360, Mexico
| | - Abigail Betanzos
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies of the National Polytechnic Institute, Av. IPN 2508, Mexico City, 07360, Mexico
| | - Jesús Serrano-Luna
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute, Av. IPN 2508, Mexico City, 07360, Mexico
| | - Mineko Shibayama
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies of the National Polytechnic Institute, Av. IPN 2508, Mexico City, 07360, Mexico
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18
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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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19
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Abstract
Blood vessels are critical to deliver oxygen and nutrients to all of the tissues and organs throughout the body. The blood vessels that vascularize the central nervous system (CNS) possess unique properties, termed the blood-brain barrier, which allow these vessels to tightly regulate the movement of ions, molecules, and cells between the blood and the brain. This precise control of CNS homeostasis allows for proper neuronal function and also protects the neural tissue from toxins and pathogens, and alterations of these barrier properties are an important component of pathology and progression of different neurological diseases. The physiological barrier is coordinated by a series of physical, transport, and metabolic properties possessed by the endothelial cells (ECs) that form the walls of the blood vessels, and these properties are regulated by interactions with different vascular, immune, and neural cells. Understanding how these different cell populations interact to regulate the barrier properties is essential for understanding how the brain functions during health and disease.
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Affiliation(s)
- Richard Daneman
- Departments of Neuroscience and Pharmacology, University of California, San Diego, San Diego, California 92093
| | - Alexandre Prat
- Department of Neuroscience, Université de Montréal, Montréal, Quebec H2X 0A9, Canada
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20
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A detailed method for preparation of a functional and flexible blood-brain barrier model using porcine brain endothelial cells. Brain Res 2013; 1521:16-30. [PMID: 23603406 PMCID: PMC3694295 DOI: 10.1016/j.brainres.2013.04.006] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 03/18/2013] [Accepted: 04/09/2013] [Indexed: 12/14/2022]
Abstract
The blood-brain barrier (BBB) is formed by the endothelial cells of cerebral microvessels and forms the critical interface regulating molecular flux between blood and brain. It contributes to homoeostasis of the microenvironment of the central nervous system and protection from pathogens and toxins. Key features of the BBB phenotype are presence of complex intercellular tight junctions giving a high transendothelial electrical resistance (TEER), and strongly polarised (apical:basal) localisation of transporters and receptors. In vitro BBB models have been developed from primary culture of brain endothelial cells of several mammalian species, but most require exposure to astrocytic factors to maintain the BBB phenotype. Other limitations include complicated procedures for isolation, poor yield and batch-to-batch variability. Some immortalised brain endothelial cell models have proved useful for transport studies but most lack certain BBB features and have low TEER. We have developed an in vitro BBB model using primary cultured porcine brain endothelial cells (PBECs) which is relatively simple to prepare, robust, and reliably gives high TEER (mean~800 Ω cm(2)); it also shows good functional expression of key tight junction proteins, transporters, receptors and enzymes. The model can be used either in monoculture, for studies of molecular flux including permeability screening, or in co-culture with astrocytes when certain specialised features (e.g. receptor-mediated transcytosis) need to be maximally expressed. It is also suitable for a range of studies of cell:cell interaction in normal physiology and in pathology. The method for isolating and growing the PBECs is given in detail to facilitate adoption of the model. This article is part of a Special Issue entitled Companion Paper.
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21
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Daneman R. The blood-brain barrier in health and disease. Ann Neurol 2012; 72:648-72. [DOI: 10.1002/ana.23648] [Citation(s) in RCA: 482] [Impact Index Per Article: 40.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 05/02/2012] [Accepted: 05/04/2012] [Indexed: 12/12/2022]
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23
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Kaya M, Ahishali B. Assessment of permeability in barrier type of endothelium in brain using tracers: Evans blue, sodium fluorescein, and horseradish peroxidase. Methods Mol Biol 2011; 763:369-382. [PMID: 21874465 DOI: 10.1007/978-1-61779-191-8_25] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Blood-brain barrier (BBB) constituted primarily by the capillary endothelial cells functions to maintain a constant environment for the brain, by preventing or slowing down the passage of a variety of blood-borne substances, such as serum proteins, chemical compounds, ions, and hormones from the circulation into the brain parenchyma. Various diseases such as brain tumors, epilepsy, and sepsis disturb the BBB integrity leading to enhanced permeability of brain microvessels. In animal models, a variety of experimental insults targeted to the BBB integrity have been shown to increase BBB permeability causing enhanced passage of molecules into the brain paranchyma by transcellular and/or paracellular pathways. This alteration can be demonstrated by intravascular infusion of exogenous tracers and subsequent detection of extravasated molecules in the brain tissue. A number of exogenous BBB tracers are available, and they can be used for functional and structural analysis of BBB permeability. In this chapter, we aimed to highlight the basic knowledge on the use of three most commonly performed tracers, namely Evans blue dye, sodium fluorescein, and horseradish peroxidase. The experimental methodologies that we use in our laboratory for the detection of these tracers by macroscopy, spectrophotometry, spectrophotofluorometry, and electron microscopy are also discussed. While tracing studies at the morphological level are mainly aimed at the identification and characterization of the tracers both in the barrier related cells and brain parenchyma, spectrophotometric and spectrophotofluorometric assays enable quantification of BBB permeability. The results of our studies that we performed using the mentioned tracers indicate that barrier type of endothelial cells in brain play an important role in paracellular and/or transcytoplasmic trafficking of macromolecules across BBB under various experimental settings, which may provide new insights in both designing approaches for the management of diseases with BBB breakdown and developing novel trans-BBB drug delivery strategies.
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Affiliation(s)
- Mehmet Kaya
- Departments of Physiology & Histology and Embryology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
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24
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Sheikov N, McDannold N, Jolesz F, Zhang YZ, Tam K, Hynynen K. Brain arterioles show more active vesicular transport of blood-borne tracer molecules than capillaries and venules after focused ultrasound-evoked opening of the blood-brain barrier. ULTRASOUND IN MEDICINE & BIOLOGY 2006; 32:1399-409. [PMID: 16965980 DOI: 10.1016/j.ultrasmedbio.2006.05.015] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Revised: 05/05/2006] [Accepted: 05/19/2006] [Indexed: 05/11/2023]
Abstract
Previously, activation of vesicular transport in the brain microvasculature was shown to be one of the mechanisms of focused ultrasound-induced blood-brain barrier (BBB) opening. In the present study, we aimed to estimate the rate of the transendothelial vesicular traffic after focused ultrasound sonication in the rabbit brain, using ultrastructural morphometry and horseradish peroxidase (HRP) as a tracer. In the capillaries, the mean endothelial pinocytotic densities (the number of HRP-containing vesicles per microm(2) of the cell cytoplasm) were 0.9 and 1.05 vesicles/microm(2) 1 h after sonication with ultrasound frequencies of 0.69 and 0.26 MHz, respectively. In the arterioles, these densities were 1.63 and 2.43 vesicles/microm(2), values 1.8 and 2.3 times higher. In control locations, the densities were 0.7 and 0.14 vesicles/microm(2) for capillaries and arterioles, respectively. A small number of HRP-positive vesicles were observed in the venules. Focal delivery of HRP tracer was also observed in light microscopy. The results indicate that the precapillary microvessels play an important role in macromolecular transcytoplasmic traffic through the ultrasound-induced BBB modulation, which should be considered in the future development of trans-BBB drug delivery strategies.
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Affiliation(s)
- Nickolai Sheikov
- Department of Radiology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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25
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Ueno M, Tomita S, Nakagawa T, Ueki M, Iwanaga Y, Ono JI, Onodera M, Huang CL, Kanenishi K, Shimada A, Maekawa N, Sakamoto H. Effects of aging and HIF-1α deficiency on permeability of hippocampal vessels. Microsc Res Tech 2006; 69:29-35. [PMID: 16416408 DOI: 10.1002/jemt.20266] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We examined age-related changes in the blood-brain barrier (BBB) of neural cell-specific hypoxia inducible factor-1alpha (HIF-1alpha) deficient mice, which showed hydrocephalus with neuronal cell loss, to investigate an effect of neural cell-specific HIF-1alpha deficiency or hydrocephalus on vascular function. Vascular permeability of horseradish peroxidase (HRP) and binding of cationized ferritin (CF) particles to the endothelial cell luminal surface, as a marker of glycocalyx, were investigated. The thickness of CF-labeled glycocalyx was significantly decreased in the cortex in mutant mice compared with that of control mice, although it was not paralleled by increased vascular permeability. In addition, strong staining for HRP was seen around vessels located along the hippocampal fissure in 24-month-old mutant mice. The reaction product of HRP appeared in an increasing number of the endothelial cell abluminal vesicles and within the thickened basal lamina of arterioles in the hippocampus, showing increased vascular permeability. There were no leaky vessels in 10-week-old mutant mice or 10-week-old and 24-month-old control mice. These findings suggest the necessity of two factors, aging and hydrocephalus, for BBB dysfunction in HIF-1alpha deficient mice.
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Affiliation(s)
- Masaki Ueno
- Department of Pathology and Host Defense, Faculty of Medicine, Kagawa University, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.
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Ueno M, Akiguchi I, Yagi H, Naiki H, Fujibayashi Y, Kimura J, Takeda T. Age-related changes in barrier function in mouse brain I. Accelerated age-related increase of brain transfer of serum albumin in accelerated senescence prone SAM-P/8 mice with deficits in learning and memory. Arch Gerontol Geriatr 2005; 16:233-48. [PMID: 15374337 DOI: 10.1016/0167-4943(93)90035-g] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/1992] [Revised: 04/16/1993] [Accepted: 04/22/1993] [Indexed: 10/27/2022]
Abstract
The time course of brain accumulation of radiolabelled human serum albumin ((125)I-HSA) injected intravenously and the transfer of (125)I-HSA from blood to brain were evaluated in DDD mice using a double isotope technique. The brain accumulation of (125)I-HSA at 3 and 9 h but not at 24 h postinjection and the brain transfer rates were significantly higher in 22-month-old DDD mice than in 4-month-old ones. The brain transfer rates of (125)I-HSA were measured also in senescence accelerated prone mice (SAM-P/8) with age-related deficits in learning and memory, and in senescence accelerated resistant mice (SAM-R/I) without these deficits. The brain transfer rates were significantly higher in 13-month-old SAM-P/8 and 22-month-old SAM-R/1 than in 3-month-old mice of the same strains, respectively. The mean brain transfer rates in five regions observed in 22-month-old DDD mice, 22-month-old SAM-R/1 and 13-month-old SAM-P/8 increased by 31%, 41% and 51% compared with corresponding values in 3- or 4-month-old mice of the same strains. DDD mice and SAM-R/1 mice with normal characteristics of aging showed similar age-related significant changes in brain transfer rates. Age-related increase in the brain transfer rate was manifested at the youngest age in SAM-P/8 among the three strains examined. These findings show that the transfer of human serum albumin into the mouse brain increases with aging and suggest that the barrier function in the mouse brain against macromolecules changes with aging.
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Affiliation(s)
- M Ueno
- Department of Senescence Biology, Chest Disease Research Institute, Kyoto University, Japan
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Ueno M, Akiguchi I, Naiki H, Fujibayashi Y, Fukuyama H, Kimura J, Kameyama M, Takeda T. The persistence of high uptake of serum albumin in the olfactory bulbs of mice throughout their adult lives. Arch Gerontol Geriatr 2005; 13:201-9. [PMID: 15374430 DOI: 10.1016/0167-4943(91)90062-u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/1991] [Revised: 05/15/1991] [Accepted: 05/17/1991] [Indexed: 10/27/2022]
Abstract
Brain to plasma concentration ratios of i.v. administered human serum albumin (HSA) in the olfactory bulb, frontal cortex and cerebellum were evaluated in DDD mice of different ages. We measured the brain uptake of serum albumin excluding intravascular content by using a double isotope technique and examined the time course of the brain uptake to evaluate the brain uptake at different time intervals. In young adult mice, the value was significantly higher in the olfactory bulb than in other brain regions 3-24 h after (125)I-HSA injection. It was about 2.3 times higher in the olfactory bulb than in the cerebellum (P < 0.01). The high concentration ratios in the olfactory bulb were observed in all 4-22-month-old mice. Moreover, the ratio in the olfactory bulb 24 h after (125)I-HSA injection was higher in 22-month-old mice than in younger animals. The high uptake of serum albumin in the olfactory bulb suggests that intravascular macromolecules can be transported into the olfactory bulb more easily than in other brain regions with tight endothelium, and the persistence of high uptake during adult life may be associated with age-related morphological changes in the olfactory bulb.
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Affiliation(s)
- M Ueno
- Department of Neurology, Kyoto University, Sakyo-ku, Kyoto 606, Japan
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28
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Abstract
(1) Three main barrier layers at the interface between blood and tissue protect the central nervous system (CNS): the endothelium of brain capillaries, and the epithelia of the choroid plexus (CP) and the arachnoid. The classical work on these barriers in situ until the 1970s laid the foundations for modern understanding. Techniques for brain endothelial cell isolation and culture pioneered by Ferenc Joó in the 1970s opened up new fields of examination, enabling study of mechanisms at the cellular and molecular level. (2) Astrocytic glial cells are closely associated with the brain endothelial barrier. During evolution the barrier appears to have shifted from the glial to the endothelial layer, in parallel with the increasing importance of the microvasculature and its regulation. Vestiges of the barrier potential of glia remain in the modern mammalian CNS. (3) Evolutionary evidence suggests that the advantage derived from ionic homeostasis around central synapses was the major selective pressure leading to refinement of CNS barrier systems. This is one element of the modern 'multitasking' barrier function. (4) While epithelia are constitutively able to form barriers at appropriate interfaces, the 'default' condition for endothelia is more leaky; inductive influences from associated cells especially astrocytes are important in generating the full blood-brain barrier (BBB) phenotype in brain capillaries. The underlying mechanisms are being elucidated at the molecular and genomics level. (5) The barrier layers of the nervous system can be modulated by a number of receptor-mediated processes, involving several signal transduction pathways, both calcium dependent and independent. Some agents acting as 'inducers' in the long term can act as 'modulators' in the short-term, with some overlap of signaling pathways. Modulating agents may be derived both from the blood and from cells associated with cerebral vessels. Less is known about the modulation of the CP. (6) The challenge for the next era of CNS barrier studies will be to apply new knowledge from proteomics and genomics to understanding the in vivo condition in physiology and pathology.
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Affiliation(s)
- N Joan Abbott
- Blood-Brain Barrier Group, Wolfson Centre for Age Related Diseases, King's College University of London, London, UK.
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Abstract
Few terms in the biomedical lexicon are as widely recognized as the phrase blood-brain barrier (BBB). Indeed, it immediately conjures up a "barricade" between the blood and the brain, a feature often considered more obstacle than safeguard. In truth, the BBB performs in both capacities, and it is precisely this duality that imparts such a vital role to the BBB in influencing physiological and pathophysiological processes in the CNS. Although the concept is more than a century old, the BBB continues to remain enigmatic in both substance and idea, with seemingly resolved issues once again beckoning for clarification. In this regard, recent technological advancements, such as sequencing of the human genome and development of microarray analysis, have illuminated novel aspects of vascular gene expression and provoked reconsideration of the cellular and biochemical makeup of the BBB. In light of the critical impact of the BBB in the realms of science and medicine, this Mini-Review will revisit the topic of the composition of the BBB, specifically highlighting how recent developments in endothelial biology have prompted a reevaluation of its precise vascular location. We have intentionally avoided discussing generalized features of the BBB, as these have been skillfully described elsewhere as noted.
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Affiliation(s)
- Shujun Ge
- Blood-Brain Barrier Laboratory, Department of Pharmacology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA
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Begley DJ, Brightman MW. Structural and functional aspects of the blood-brain barrier. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2003; 61:39-78. [PMID: 14674608 DOI: 10.1007/978-3-0348-8049-7_2] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- David J Begley
- Centre for Neuroscience Research, Kings College London, Hodgkin Building, Guy's Campus, London SE1 1UL, UK.
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Ueno M, Sakamoto H, Kanenishi K, Onodera M, Akiguchi I, Hosokawa M. Ultrastructural and permeability features of microvessels in the hippocampus, cerebellum and pons of senescence-accelerated mice (SAM). Neurobiol Aging 2001; 22:469-78. [PMID: 11378254 DOI: 10.1016/s0197-4580(01)00213-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We previously reported that the accumulation of blood-borne radiolabelled serum albumin in brain parenchyma increased with aging, especially in senescence-accelerated mice (SAMP8), which showed age-related deficits in learning and memory. In this study, in order to examine morphological events related to the age-related increase of the brain accumulation of serum albumin, the transvascular passage of blood-borne horseradish peroxidase (HRP) and ultrastructural features of microvessels were examined in the hippocampus, cerebellum and pons of SAMP8 and SAMR1 (control) mice. Ultrastructural examination of the hippocampus showed that the staining for HRP was occasionally spreading throughout the parajunctional cytoplasm of the endothelial cell of aged SAMP8 mice, but not in young SAMP8 mice nor in SAMR1 mice. The number of vessels showing the staining reaction for HRP in the parajunctional cytoplasm of the endothelial cells in aged SAMP8 mice increased significantly compared with that in the others. Electron microscopic morphometry showed that there were no significant differences among the number of HRP-positive vesicles per unit area of the endothelial cell cytoplasm in young and old mice of both strains. The staining reaction for HRP was not seen in the basal lamina of microvessels and the perivascular neuropil in all mice examined. Perivascular lipofuscin-like granules and collagen deposits, swelling of astroglial perivascular endfeet and perivascular cells containing foamy, lipid-like droplets were frequently found in several brain regions of aged SAMP8 mice. The perivascular cells with a few lipid-like droplets and more electron-homogeneous lysosomes were occasionally seen in SAMR1 and young SAMP8, while the other findings were scarcely observed in SAMR1 and young SAMP8 mice. These findings suggest that the blood-brain barrier to HRP was preserved in microvessels in three brain regions of SAM mice but the blood microvessels showed some age-related ultrastructural alterations in SAMP8 brains. Uncontrolled passage of HRP through the parajunctional cytoplasm of the endothelial cells may partly contribute to the age-related increase of accumulation of serum albumin in SAMP8 brains.
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Affiliation(s)
- M Ueno
- Second Department of Pathology, Kagawa Medical University, 1750-1 Ikenobe, Miki-cho, Kita-gun, 761-0793, Kagawa, Japan.
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Ueno M, Sakamoto H, Kanenishi K, Onodera M, Akiguchi I, Hosokawa M. Ultrastructural and permeability features of microvessels in the periventricular area of senescence-accelerated mice (SAM). Microsc Res Tech 2001; 53:232-8. [PMID: 11301499 DOI: 10.1002/jemt.1088] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Brain transfer of intravenously injected horseradish peroxidase (HRP) and the ultrastructural features of the vessels were examined in periventricular areas in senescence-accelerated mice (SAMP8), which show age-related deficits in learning and memory, and senescence-accelerated resistant mice (SAMR1), which do not show age-related deficits. In all mice examined with light microscopy, staining reaction for HRP was seen in the periventricular area adjacent to the medial side of the lateral ventricle. Electron microscopic examination in the periventricular area of young and old mice of both strains showed that the staining reaction for HRP appeared in the vesicular profiles of the endothelial cytoplasm, the cytoplasm of the perivascular cells, the basal lamina, and the adjoining extracellular spaces of the white matter, suggesting an incomplete blood-brain barrier (BBB) in the periventricular white matter. In addition, irregularly thickened endothelial cell cytoplasm, membranous inclusions within the basal lamina, and electron-dense endothelial cell cytoplasm were occasionally seen in aged SAMP8 mice. These findings were not observed in 3-month-old SAMP8 mice and 3- and 13-month-old SAMR1 mice. Perivascular collagen deposits were also frequently seen in aged SAMP8 mice. These findings indicate that the endothelial cells and pericytes in the periventricular white matter in aged SAMP8 mice have an ultrastructure with damaged BBB function. Intravascular substances can easily penetrate the periventricular white matter and the BBB of the vessels in the area can be deteriorated with aging in SAMP8 mice.
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Affiliation(s)
- M Ueno
- Department of Pathology II, Kagawa Medical University, Kagawa, Japan.
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Fullerton SM, Shirman GA, Strittmatter WJ, Matthew WD. Impairment of the blood-nerve and blood-brain barriers in apolipoprotein e knockout mice. Exp Neurol 2001; 169:13-22. [PMID: 11312553 DOI: 10.1006/exnr.2001.7631] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Apolipoprotein E (apoE) is well characterized as a plasma lipoprotein involved in lipid and cholesterol metabolism. Recent studies implicating apoE in Alzheimer's disease and successful recovery from neurological injury have stimulated much interest in the functions of apoE within the brain. To explore the functions of apoE within the nervous system, we examined apoE knockout (KO) mice. Previously, we showed that apoE KO mice have a delayed response to noxious thermal stimuli associated with a loss and abnormal morphology of unmyelinated fibers in the sciatic nerve. From these data, we hypothesized that apoE KO mice could have an impaired blood-nerve barrier (BNB). In this report, we demonstrate functionally impaired blood-nerve and blood-brain barriers (BBB) in apoE KO mice using immunofluorescent detection of serum protein leakage into nervous tissue as a diagnostic for decreased BNB and BBB integrity. Extensive extravasation of serum immunoglobulin G (IgG) is detected in the sciatic nerve, spinal cord, and cerebellum of apoE KO but not WT mice. In a subpopulation of apoE KO mice, IgG also extravasates into discrete cortical and subcortical locations, including hippocampus. Loss of BBB integrity was additionally confirmed by the ability of exogenously supplied Evans blue dye to penetrate the BBB and to colocalize with IgG immunoreactivity in CNS tissue. These observations support a role for apoE in maintaining the integrity of the BNB/BBB and suggest a novel relationship between apoE and neural injury.
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Affiliation(s)
- S M Fullerton
- Department of Neurobiology, Duke University Medical Center, Durham, North Carolina, 27710, USA
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Shinnou M, Ueno M, Sakamoto H, Ide M. Blood-brain barrier damage in reperfusion following ischemia in the hippocampus of the Mongolian gerbil brain. Acta Neurol Scand 1998; 98:406-11. [PMID: 9875619 DOI: 10.1111/j.1600-0404.1998.tb07322.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Vascular permeability to intravenously injected horseradish peroxidase (HRP) was qualitatively examined in the hippocampus of ischemic Mongolian gerbil brains by light and electron microscopy. After 30 min of right common carotid artery occlusion followed by 90 min of reperfusion, the animal was perfused with a fixative and killed. Before the perfusion of the fixative, HRP was injected into the femoral vein. HRP was visualized with tetramethyl benzidine (TMB) and diamino-benzidine (DAB) for light and electron microscopy, respectively. Staining reaction with TMB for HRP appeared in medial or dorsal portions of the operated side of the hippocampus, especially around some vessels along the hippocampal fissure. Ultrastructural examination in the vessels along hippocampal fissure revealed that the endothelial cytoplasm contained HRP-filled vesicles or vacuoles in close proximity to the basal lamina, and seemed to be slightly electron-dense. Swollen pericytes, swollen astrocytic foot processes and perivascular cells with HRP-filled cytoplasm were also observed in that area. In this study, it was clearly demonstrated that intravascular macromolecules leaked transendothelially, through vessel walls in the hippocampal fissure, from the blood stream in the medial portions of the hippocampus during reperfusion following ischemia. These findings suggest that the blood-brain barrier in some vessels along the hippocampal fissure in the medial parts of the hippocampus is more vulnerable to ischemic insults than those in other brain areas.
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Affiliation(s)
- M Shinnou
- Second Department of Pathology, Kagawa Medical University, Japan
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Thomas SA, Segal MB. The transport of the anti-HIV drug, 2',3'-didehydro-3'-deoxythymidine (D4T), across the blood-brain and blood-cerebrospinal fluid barriers. Br J Pharmacol 1998; 125:49-54. [PMID: 9776343 PMCID: PMC1565597 DOI: 10.1038/sj.bjp.0702044] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. The brain is a site of infection, viral replication and sanctuary for HIV-1. The treatment of HIV-1 infection therefore requires that an effective agent be delivered to the brain. 2',3'-Didehydro-3'-deoxythymidine (D4T) is a nucleoside analogue which has been shown to have beneficial clinical effects in the treatment of HIV infection. However, although D4T has been detected in human CSF, the ability of this drug to cross both the blood-brain and blood-cerebrospinal fluid (CSF) barriers and gain entrance into the brain tissue is not known. 2. This study examined the CNS entry of D4T by means of the bilateral vascular brain perfusion technique in the anaesthetized guinea-pig. 3. The results indicated that [3H]-D4T had a limited ability to cross the blood-brain barrier (BBB), which was not significantly greater than D-[14C]-mannitol (a slowly penetrating marker molecule). Although D4T was found to cross the blood-CSF barrier, the presence of D4T in the CSF did not reflect levels of the drug in the brain tissue. 4. These results can be related to the measured low lipophilicity of D4T, the higher paracellular permeability characteristics of the choroid plexus (blood-CSF barrier) compared to the BBB, and the sink action nature of the CSF to the brain tissue. 5. In conclusion, these animal studies suggest that D4T may only penetrate the brain tissue to a limited extent and consideration should be given to these findings in the clinical situation.
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Affiliation(s)
- S A Thomas
- Sherrington School of Physiology, U.M.D.S., St. Thomas Hospital Campus, London
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36
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Abstract
Wernicke's Encephalopathy (WE) is a serious neurological disorder resulting from thiamine deficiency, encountered in chronic alcoholics and in patients with grossly impaired nutritional status. Neuropathologic studies as well as Magnetic Resonance Imaging reveal selective diencephalic and brainstem lesions in patients with WE. The last decade has witnessed major advances in the understanding of pathophysiologic mechanisms linking thiamine deficiency to the selective brain lesions characteristic of WE. Activities of the thiamine-dependent enzyme alpha-ketoglutarate dehydrogenase, a rate-limiting tricarboxylic acid cycle enzyme are significantly reduced in autopsied brain tissue from patients with WE and from rats treated with the central thiamine antagonist, pyrithiamine. In the animal studies, evidence suggests that such enzyme deficits result in focal lactic acidosis, cerebral energy impairment and depolarization resulting from increased release of glutamate in vulnerable brain structures. It has been proposed that this depolarization may result in N-Methyl-D-Aspartate receptor-mediated excitotoxicity as well as increased expression of immediate early genes such as c-fos and c-jun resulting in apoptotic cell death. Other mechanisms involved in thiamine deficiency-induced cell loss may involve free radicals and alterations of the blood-brain barrier. Additional studies are still required to identify the site of the initial cellular insult and to explain the predilection of diencephalic and brainstem structures due to thiamine deficiency.
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Affiliation(s)
- A S Hazell
- Neuroscience Research Unit, Centre Hospitalier de l'Université de Montréal (Campus Saint-Luc), Quebec, Canada.
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Cassella JP, Lawrenson JG, Lawrence L, Firth JA. Differential distribution of an endothelial barrier antigen between the pial and cortical microvessels of the rat. Brain Res 1997; 744:335-8. [PMID: 9027393 DOI: 10.1016/s0006-8993(96)00974-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
An endothelial barrier antigen (EBA), reported to be a marker for endothelial cells (EC) displaying blood-brain barrier (BBB) characteristics, was probed with a monoclonal antibody in pial and cortical microvessels in rat brain. In contrast to the uniform labelling of EC in cortical vessels, pial microvessels showed a heterogeneity in EBA expression. Most pial vessels consisted of a mixture of EBA positive and EBA negative cells whereas a smaller number of vessels were either completely negative or uniformly positive. Significantly, in vessels showing incomplete expression it was typically EC furthest from the brain surface that did not express EBA. Although the function of EBA is unknown, the variable expression in pial microvascular EC may be related to their incomplete barrier characteristics.
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Affiliation(s)
- J P Cassella
- Department of Anatomy and Cell biology, St Mary's Hospital Medical School, Imperial College of Science Technology and Medicine, London, UK
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Zumkeller M, Dietz H. Ultrastructural changes in the blood-brain barrier in rats after treatment with nimodipine and flunarizine. A comparison. Neurosurg Rev 1996; 19:253-60. [PMID: 9007889 DOI: 10.1007/bf00314841] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The idea of using induced hypertension to treat the symptomatic ischaemia resulting from vasospasm after subarachnoidal hemorrhage, and the effect of this therapy on the blood-brain barrier, is checked in animal experiments. This therapy is combined with the application of nimodipine, which is recognised as the standard medication for prophylaxis of vasospasm. The effects of the induced hypertension combination with Nimodipine and in combination with another calcium antagonist, Flunarizine are compared. Seventy-four narcotised rats, one group with 22 animals treated with Nimodipine and 22 with placebo, and a second group 20 animals treated with Flunarizine and 10 with placebo, are evaluated. The blood pressure is raised to 150-180 mmHg by i.v. application of norfenephrine and measured continuously. The standard tracer, horseradish peroxidase, is applied as indicator for the blood-brain barrier function. 15 minutes later the experimental animals are exsanguinated by perfusion with saline, then perfused with Karnovsky's solution. After removal, the brains are stained for peroxidase to visualise extravasation of the horseradish peroxidase, and after evaluation of the results each brain is assigned to its experimental group. In the Nimodipine group, a significant accumulation (p < 0.001) of perivascular deposits of peroxidase reaction product were found, these were not found in the placebo group. The Flunarizine group does not differ from its placebo group in the number of extravasates, and thus, with respect to protein extravasation, appears better than the Nimodipine group. In electron micrographs of the extravasates one sees intact tight junctions and a neuroendothelial transport, and also vesicles, filled with horseradish peroxidase in the endothelium, the muscle cells, and the brain parenchyma, which arise from pinocytosis. The vesicles, which transport the high-molecular-weight protein, horseradish peroxidase, also transport other proteins and can, therefore, cause a brain edema. It follows from these morphological results that Nimodipine can disrupt the blood brain barrier function and can, therefore, also interfere with cerebral autoregulation, which depends on the resistance of vessels.
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Affiliation(s)
- M Zumkeller
- Neurosurgical Clinic, University Hannover, Medical School, Fed. Rep. of Germany
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Noble LJ, Kalinyak JE, Pitts LH, Hall JJ. Fluid-phase endocytosis of horseradish peroxidase by cerebral endothelial cells in primary culture: characterization and kinetic analysis. J Neurosci Res 1994; 38:654-63. [PMID: 7807581 DOI: 10.1002/jnr.490380608] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Endocytosis of horseradish peroxidase (HRP) was studied in primary cultures of cerebral endothelial cells prepared from 2-week-old rats. These cultures were considered "endothelial-like" on the basis of their ability to internalize acetylated low density lipoprotein. Cellular localization of HRP protein was examined at the light and ultrastructural levels and endocytosis of the protein was evaluated by a colorimetric assay. HRP was localized in discrete cytoplasmic granules by light microscopy. At the ultrastructural level these granules corresponded to pleomorphic membrane-bound structures that were present throughout the cytoplasm. The amount of internalized HRP was directly related to the concentration of the protein in the medium, was not saturable at high concentrations of HRP, and increased with time. Endocytosis proceeded at 37 degrees C, but was abolished at 4 degrees C. In pulse-chase experiments, the quantity of internalized protein in the cells did not significantly change during the 2 hr chase period. Taken together, these findings suggest that internalization of HRP occurs by fluid-phase endocytosis, a non-receptor-mediated process, and that the protein is stable within an intracellular compartment for at least several hours.
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Affiliation(s)
- L J Noble
- Department of Neurosurgery, University of California, San Francisco 94110
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Aihara N, Tanno H, Hall JJ, Pitts LH, Noble LJ. Immunocytochemical localization of immunoglobulins in the rat brain: relationship to the blood-brain barrier. J Comp Neurol 1994; 342:481-96. [PMID: 8040362 DOI: 10.1002/cne.903420402] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The central nervous system has been traditionally regarded as an immunologically privileged area. This feature has been in part attributed to the blood-brain barrier, which provides a restrictive interface to circulating immunoglobulins (IgG). Recent kinetic studies suggest that the barrier to immune proteins is not absolute, but rather may be regulated by a specific transfer mechanism. In this study, we confirm the presence of IgG in the central nervous system by immunocytochemistry and demonstrate a close anatomical relationship between the distribution of this protein and the blood-brain barrier. IgG was immunolocalized in the normal rat brain by using monoclonal and polyclonal antibodies to IgG and its subclasses. On the basis of an initial evaluation, the most appropriate antibodies and dilutions were selected for subsequent analyses. In the first study, IgG and albumin were immunolocalized in adjacent sections. In the second study, horseradish peroxidase (HRP) was given intravenously prior to sacrifice, in order to examine artifacts related to perfusion fixation. The distribution of HRP and IgG was then examined in adjacent sections. In the third study, IgG was immunolocalized in sections of brain after mild traumatic head injury. A monoclonal antibody to IgG2a and a polyclonal antibody to IgG were selected on the basis of specificity and consistent, mutual localization. Distinct, patchy, perivascular staining, infrequently associated with labeled neurons, was noted throughout the brain. Electron microscopy confirmed the perivascular localization; IgG was localized along the basal lamina of microvasculature and within the adjacent parenchyma. Albumin and HRP did not exhibit a similar pattern of perivascular immunostaining. After head injury, prominent immunostaining for IgG was observed in the injured hemisphere. In summary, these data indicate that the normal rat brain contains IgG, which dramatically increases after head injury. The distinct perivascular distribution in the normal brain suggests local microvascular permeability. This permeability is selective for IgG, since albumin does not share a similar perivascular localization. The neuronal staining which is closely associated with perivascular label may reflect one intracellular route for extravasated IgG.
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Affiliation(s)
- N Aihara
- Department of Neurosurgery, University of California, San Francisco
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41
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Joó F. Insight into the regulation by second messenger molecules of the permeability of the blood-brain barrier. Microsc Res Tech 1994; 27:507-15. [PMID: 8012053 DOI: 10.1002/jemt.1070270605] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Recent advances in our knowledge of the blood-brain barrier have in part been made by studying the properties and function of cerebral endothelial cells in vitro. After an era of working with a fraction, enriched in cerebral microvessels by centrifugation, the next generation of in vitro blood-brain barrier model systems was introduced, when the conditions for routinely culturing the endothelial cells were established. This review summarizes the results obtained mainly from this in vitro approach. Different elements of the intracellular signaling messenger systems have been detected in the course of our studies in the cerebral endothelial cells. It has been shown that the synthesizing enzymes of and substrate proteins for the second messenger molecules are present in the cerebral endothelial cells, and their activity and/or amount can change in pathological circumstances, i.e., during the formation of brain oedema. Pharmacological treatments interfering with the second messenger systems proved to be effective in the prevention of brain oedema formation.
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Affiliation(s)
- F Joó
- Laboratory of Molecular Neurobiology, Biological Research Center, Szeged, Hungary
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Rubin P, Gash DM, Hansen JT, Nelson DF, Williams JP. Disruption of the blood-brain barrier as the primary effect of CNS irradiation. Radiother Oncol 1994; 31:51-60. [PMID: 8041898 DOI: 10.1016/0167-8140(94)90413-8] [Citation(s) in RCA: 128] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The blood-brain barrier (BBB) is believed to be unique in organ microcirculation due to the 'tight junctions' which exist between endothelial cells and, some argue, the additional functional components represented by the perivascular boundary of neuroglial cells; these selectively exclude proteins and drugs from the brain parenchyma. This study was designed to examine the effects of irradiation on the BBB and determine the impact of the altered pathophysiology on the production of central nervous system (CNS) late effects such as demyelination, gliosis and necrosis. Rats, irradiated at 60 Gy, were serially sacrificed at 2, 6, 12 and 24 weeks. Magnetic resonance image analysis (MRI) was obtained prior to sacrifice with selected animals from each group. The remaining animals underwent horse-radish peroxidase (HRP) perfusion at the time of sacrifice. The serial studies showed a detectable disruption of the BBB at 2 weeks post-irradiation and this was manifested as discrete leakage; late injury seen at 24 weeks indicated diffuse vasculature leakage, severe loss of the capillary network, cortical atrophy and white matter necrosis. Reversal or repair of radiation injury was seen between 6 and 12 weeks, indicating a bimodal peak in events. Blood-brain barrier disruption is an early, readily recognizable pathophysiological event occurring after radiation injury, is detectable in vivo/in vitro by MRI and HRP studies, and appears to precede white matter necrosis. Dose response studies over a wide range of doses, utilizing both external and interstitial irradiation, are in progress along with correlative histopathologic and ultrastructural studies.
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Affiliation(s)
- P Rubin
- Department of Radiation Oncology, University of Rochester, NY 14642
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Joó F, Kovács J, Szerdahelyi P, Temesvári P, Tósaki A. The role of histamine in brain oedema formation. ACTA NEUROCHIRURGICA. SUPPLEMENTUM 1994; 60:76-8. [PMID: 7976661 DOI: 10.1007/978-3-7091-9334-1_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effects of histamine on the cerebral endothelial cells were studied. To determine if the extent of brain oedema formation could be reduced with histamine receptor antagonists, mepyramine (H1-receptor blocker), metiamide, cimetidine and ranitidine (H2-receptor antagonists) were administered at a dose of 5 mg/kg body weight 4, 2 and 0 h before the onset of experimental pneumothorax induced in newborn piglets. Mepyramine and ranitidine given 2 h before the induction of EBP prevented the accumulation of water, sodium and albumin in samples taken from the parietal cortex. In other experiments, carried out on Sprague-Dawley rats of CFY strain after permanent bilateral common carotid ligation (BCCL), the accumulation of water and sodium in the ischemic brain tissue could also be prevented in a dose dependent manner by intraperitoneal injections of ranitidine given 30 min before the surgery. Taken together, these results provide pharmacological evidence for the involvement of histamine receptors in the pathogenesis of brain oedema. Consequently, the use of histamine receptor blockers both in the prevention and in the treatment of brain oedema can be recommended.
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Affiliation(s)
- F Joó
- Laboratory of Molecular Neurobiology, Biological Research Center, Szeged, Hungary
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Vásquez JV, Pinardi G. Vasomotor responses in the isolated perfused external and internal carotid vascular beds of the rat. GENERAL PHARMACOLOGY 1992; 23:775-80. [PMID: 1397985 DOI: 10.1016/0306-3623(92)90165-g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
1. The external (ECB) or the internal (ICB) carotid vascular beds of the rat were isolated and perfused with Krebs-Henseleit solution at constant flow (1 ml/min). Changes in perfusion pressure (PP) were recorded after cervical sympathetic stimulation and after the administration of norepinephrine (NE) and serotonin (5-HT). 2. Sympathetic stimulation induced an increase in PP (vasoconstriction) in both vascular beds, however, this effect was significantly higher in the ECB than in the ICB. 3. Exogenous NE also induced a significantly higher contractile response in the ECB. 4. Prazosin (10(-8) M) significantly inhibited the response to sympathetic stimulation and to NE both in the ECB and in the ICB, but yohimbine (10(-7) M) had no effect, suggesting that the vasoconstriction was mainly due to the activation of alpha 1-adrenoceptors. 5. 5-HT induced a contractile response both in the ECB and the ICB. In contrast with the response to NE, the contraction induced by 5-HT in the ICB was significantly higher than in the ECB. 6. Ketanserine (10(-8) M) antagonised both responses, indicating the involvement of 5-HT2 receptors. 7. The contractile effect of 5-HT in the ECB was significantly enhanced by a subthreshold sympathetic stimulation that did not modify the PP by itself. This effect was not seen in the ICB. 8. The differential perfusions of the ECB or the ICB demonstrated a different reactivity of ECB and ICB, both to sympathetic stimulation and to the administration of exogenous NE or 5-HT. 9. Furthermore, the response to 5-HT in the ECB was modulated by a subthreshold sympathetic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J V Vásquez
- Department of Physiopathology, Vargas School of Medicine, Faculty of Medicine Central University of Venezuela, Caracas
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Dimitriadou V, Buzzi MG, Theoharides TC, Moskowitz MA. Ultrastructural evidence for neurogenically mediated changes in blood vessels of the rat dura mater and tongue following antidromic trigeminal stimulation. Neuroscience 1992; 48:187-203. [PMID: 1374861 DOI: 10.1016/0306-4522(92)90348-6] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We investigated the effects of unilateral electrical trigeminal ganglion stimulation (0.1 or 1.0 mA, 5 Hz, 5 ms, 5 min) on the morphology of blood vessels within the rat dura mater and tongue using light and transmission electron microscopy. Stimulation at both intensities caused changes which were confined to the ipsilateral post-capillary venules except in the tongue where arterioles were affected as well. Changes were more marked after 1.0 mA. Dramatic increases in the numbers of endothelial pinocytotic vesicles were found along the luminal and abluminal surfaces ipsilateral to the stimulation. Tight junctions remained largely intact, except that injected ferritin particles were occasionally trapped inside these junctions. Cytoplasmic microvilli and endothelial blebs were sometimes present as well. Approximately 80% of the examined dural post-capillary venules showed one or more of these endothelial changes. Horseradish peroxidase injected intravenously 5 min prior to stimulation was detected in the extracellular space surrounding dural blood vessels and within pinocytotic vesicles. Ferritin injected similarly, was also localized in post-capillary venule walls, interstitial spaces, intraendothelial vesicles and in vacuoles. Platelet accumulation and aggregation were present in approximately 10% of post-capillary venules in dura and tongue. These changes were associated with mast cell secretion, but neither vascular nor mast cell activation was observed in adult rats in whom C-fibers were destroyed during the neonatal period with capsaicin. The present observations provide morphological evidence which supports findings from previously reported albumin tracer studies suggesting enhanced transport and endothelial activation following electrical stimulation of small caliber afferent fibers.
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Affiliation(s)
- V Dimitriadou
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111
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46
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Joó F, Lengyel I, Kovács J, Penke B. Chapter 26: Regulation of transendothelial transport in the cerebral microvessels: the role of second messengers-generating systems. PROGRESS IN BRAIN RESEARCH 1992; 91:177-87. [PMID: 1357721 DOI: 10.1016/s0079-6123(08)62333-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
Different elements of the intracellular signaling messenger systems have been detected in the course of our studies in the cerebral endothelial cells. It has been shown that the synthesizing enzymes of and substrate proteins for the second messenger molecules are present in the cerebral endothelial cells, and their activity and/or amount can change in pathological circumstances, i.e., during the formation of brain oedema. Pharmacological treatments interfering with the second messenger systems proved to be effective in the prevention of brain oedema formation.
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Affiliation(s)
- F Joó
- Laboratory of Molecular Neurobiology, Biological Research Center, Szeged, Hungary
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Frey A, Meckelein B, Weiler-Güttler H, Möckel B, Flach R, Gassen HG. Pericytes of the brain microvasculature express gamma-glutamyl transpeptidase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 202:421-9. [PMID: 1684747 DOI: 10.1111/j.1432-1033.1991.tb16391.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The expression of gamma-glutamyl transpeptidase (GGT) is a specific property of the brain capillary endothelium that constitutes the blood-brain barrier. We report here the detection of GGT, not only in endothelial cells, but also in pericytes, demonstrating that a brain capillary-specific pericyte population exists. We raised antibodies to GGT using a porcine brain microvessel GGT-protein-A (staphylococcal protein A) fusion protein as antigen which was expressed in Escherichia coli. The immunohistochemical analysis of the subcapillary distribution of GGT in porcine brain cortex and cerebellum sections by both light and electron microscopy revealed the expression of GGT in the capillary-adjacent pericytes in addition to the GGT-positive endothelial layer. We confirmed these data for cultured porcine brain microvascular endothelial cells and pericytes. GGT immunofluorescence could be detected in both cell types in culture. Endothelial cells exhibited a weak staining, whereas pericytes were strongly positive for GGT. Due to the high phagocytotic activity of pericytes and their location on the abluminal surface of the microvessels, we propose a possible protective or detoxifying function of GGT in cerebrovascular pericytes.
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Affiliation(s)
- A Frey
- Institut für Biochemie, Technische Hochschule Darmstadt, Federal Republic of Germany
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48
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Polder TW, Jerusalem CR, Eling WM. Morphological characteristics of intracerebral arterioles in clinical (Plasmodium falciparum) and experimental (Plasmodium berghei) cerebral malaria. J Neurol Sci 1991; 101:35-46. [PMID: 2027026 DOI: 10.1016/0022-510x(91)90016-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Spastic constriction of intracerebral arterioles was identified in clinical (P. falciparum) and experimental (P. berghei) cerebral malaria. Morphological criteria were used to characterize pathologically spastic constriction of arterioles. The significance of spastic constriction of intracerebral arterioles for microcirculatory disturbance in relation to development of cerebral malaria is discussed.
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Affiliation(s)
- T W Polder
- Department of Neurosurgery, University Hospital Nijmegen, The Netherlands
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Holash JA, Sugamori K, Stewart PA. The difference in vascular volume between cerebrum and cerebellum is in the pia mater. J Cereb Blood Flow Metab 1990; 10:432-4. [PMID: 2329130 DOI: 10.1038/jcbfm.1990.75] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Previous studies using intravascular tracers have shown that the apparent vascular volume in the cerebellum is 10-60% higher than that in the cerebrum. We questioned whether the extravascular volume in the cerebellum could be accounted for by the vasculature of the pia mater that covers its highly infolded surface. Estimates of vascular volume were made using a previously reported point-counting method. Two counts were done: one in which only intraparenchymal vessels were included, and a second one in which both intraparenchymal vessels and pial vessels were included. We found no differences in intraparenchymal vascular volume between cerebellum and cerebrum. When the pial vessels are included, however, the cerebral vascular volume increases by less than 6%, whereas the cerebellar vascular volume increases by greater than 30%. We suggest that the higher cerebellar vascular volume measured using intravascular tracers is due to inclusion of the pial vasculature. Since pial vessels do not express blood-brain barrier characteristics as prominently as intraparenchymal vessels, we further suggest that estimates of barrier permeability in cerebellum should not be made using simple models developed for cerebral tissue.
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Affiliation(s)
- J A Holash
- Department of Anatomy, University of Toronto, Ontario, Canada
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Broadwell RD. Transcytosis of macromolecules through the blood-brain barrier: a cell biological perspective and critical appraisal. Acta Neuropathol 1989; 79:117-28. [PMID: 2688350 DOI: 10.1007/bf00294368] [Citation(s) in RCA: 137] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A critical appraisal is presented of nearly two decades of research publications and review articles advocating the bidirectional transcytosis of fluid-phase molecules, most notably native horseradish peroxidase (HRP), through the normal and experimentally modified blood-brain barrier (BBB). Extracellular routes circumventing the BBB in normal and pathological states and artifact introduced in histological preparation of CNS tissue exposed to blood-borne peroxidase are emphasized. The potential for transcytosis of macromolecules entering the nonfenestrated cerebral endothelium by the processes of non-specific fluid phase endocytosis (e.g., HRP), adsorptive endocytosis (e.g., lectins) and receptor-mediated endocytosis (e.g., ligands) is analyzed in the context of the cellular secretory process and the complimentary events of endocytosis and exocytosis at the luminal and abluminal plasma membranes. Available data suggest that the cerebral endothelium is polarized with regard to endocytosis and the internalization of cell surface membrane; hence, the transcytosis of specific macromolecules through the BBB may be vectorial. If these data are correct, the blood-brain barrier is not absolute, whereas its counterpart, the brain-blood barrier, may be.
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Affiliation(s)
- R D Broadwell
- Division of Neurological Surgery, University of Maryland School of Medicine, Baltimore 21201
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