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Malik JR, Fletcher CV, Podany AT, Dyavar SR, Scarsi KK, Pais GM, Scheetz MH, Avedissian SN. A novel 4-cell in-vitro blood-brain barrier model and its characterization by confocal microscopy and TEER measurement. J Neurosci Methods 2023; 392:109867. [PMID: 37116621 PMCID: PMC10275325 DOI: 10.1016/j.jneumeth.2023.109867] [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: 02/28/2023] [Revised: 04/18/2023] [Accepted: 04/25/2023] [Indexed: 04/30/2023]
Abstract
The blood-brain barrier (BBB) is a protective cellular anatomical layer with a dynamic micro-environment, tightly regulating the transport of materials across it. To achieve in-vivo characteristics, an in-vitro BBB model requires the constituent cell types to be layered in an appropriate order. A cost-effective in-vitro BBB model is desired to facilitate central nervous system (CNS) drug penetration studies. Enhanced integrity of tight junctions observed during the in-vitro BBB establishment and post-experiment is essential in these models. We successfully developed an in-vitro BBB model mimicking the in-vivo cell composition and a distinct order of seeding primary human brain cells. Unlike other in-vitro BBB models, our work avoids the need for pre-coated plates for cell adhesion and provides better cell visualization during the procedure. We found that using bovine collagen-I coating, followed by bovine fibronectin coating and poly-L-lysine coating, yields better adhesion and layering of cells on the transwell membrane compared to earlier reported use of collagen and poly-L-lysine only. Our results indicated better cell visibility and imaging with the polyester transwell membrane as well as point to a higher and more stable Trans Endothelial Electrical Resistance values in this plate. In addition, we found that the addition of zinc induced higher claudin 5 expressions in neuronal cells. Dolutegravir, a drug used in the treatment of HIV, is known to appear in moderate concentrations in the CNS. Thus, dolutegravir was used to assess the functionality of the final model and cells. Using primary cells and an in-house coating strategy substantially reduces costs and provides superior imaging of cells and their tight junction protein expression. Our 4-cell-based BBB model is a suitable experimental model for the drug screening process.
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Affiliation(s)
- Johid R Malik
- Antiviral Pharmacology Laboratory, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, USA
| | - Courtney V Fletcher
- Antiviral Pharmacology Laboratory, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, USA; Division of Infectious Diseases, Department of Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Anthony T Podany
- Antiviral Pharmacology Laboratory, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, USA
| | | | - Kimberly K Scarsi
- Antiviral Pharmacology Laboratory, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, USA; Division of Infectious Diseases, Department of Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Gwendolyn M Pais
- Department of Pharmacy Practice, Chicago College of Pharmacy, Midwestern University, Downers Grove, IL, USA; Midwestern University, College of Pharmacy Center of Pharmacometric Excellence, Downers Grove, IL, USA
| | - Marc H Scheetz
- Department of Pharmacy Practice, Chicago College of Pharmacy, Midwestern University, Downers Grove, IL, USA; Midwestern University, College of Pharmacy Center of Pharmacometric Excellence, Downers Grove, IL, USA
| | - Sean N Avedissian
- Antiviral Pharmacology Laboratory, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE, USA.
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Cytoskeleton Elements Contribute to Prion Peptide-Induced Endothelial Barrier Breakdown in a Blood–Brain Barrier In Vitro System. Int J Mol Sci 2022; 23:ijms232012126. [PMID: 36293002 PMCID: PMC9603506 DOI: 10.3390/ijms232012126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/02/2022] [Accepted: 10/07/2022] [Indexed: 11/17/2022] Open
Abstract
The mechanisms involved in the interaction of PrP 106-126, a peptide corresponding to the prion protein amyloidogenic region, with the blood–brain barrier (BBB) were studied. PrP 106-126 treatment that was previously shown to impair BBB function, reduced cAMP levels in cultured brain endothelial cells, increased nitric oxide (NO) levels, and changed the activation mode of the small GTPases Rac1 (inactivation) and RhoA (activation). The latter are well established regulators of endothelial barrier properties that act via cytoskeletal elements. Indeed, liquid chromatography-mass spectrometry (LC-MS)-based proteomic profiling study revealed extensive changes in expression of cytoskeleton-related proteins. These results shed light on the nature of the interaction between the prion peptide PrP 106-126 and the BBB and emphasize the importance of the cytoskeleton in endothelium response to prion- induced stress.
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Neumaier F, Zlatopolskiy BD, Neumaier B. Drug Penetration into the Central Nervous System: Pharmacokinetic Concepts and In Vitro Model Systems. Pharmaceutics 2021; 13:1542. [PMID: 34683835 PMCID: PMC8538549 DOI: 10.3390/pharmaceutics13101542] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 09/17/2021] [Accepted: 09/20/2021] [Indexed: 12/22/2022] Open
Abstract
Delivery of most drugs into the central nervous system (CNS) is restricted by the blood-brain barrier (BBB), which remains a significant bottleneck for development of novel CNS-targeted therapeutics or molecular tracers for neuroimaging. Consistent failure to reliably predict drug efficiency based on single measures for the rate or extent of brain penetration has led to the emergence of a more holistic framework that integrates data from various in vivo, in situ and in vitro assays to obtain a comprehensive description of drug delivery to and distribution within the brain. Coupled with ongoing development of suitable in vitro BBB models, this integrated approach promises to reduce the incidence of costly late-stage failures in CNS drug development, and could help to overcome some of the technical, economic and ethical issues associated with in vivo studies in animal models. Here, we provide an overview of BBB structure and function in vivo, and a summary of the pharmacokinetic parameters that can be used to determine and predict the rate and extent of drug penetration into the brain. We also review different in vitro models with regard to their inherent shortcomings and potential usefulness for development of fast-acting drugs or neurotracers labeled with short-lived radionuclides. In this regard, a special focus has been set on those systems that are sufficiently well established to be used in laboratories without significant bioengineering expertise.
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Affiliation(s)
- Felix Neumaier
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany; (B.D.Z.); (B.N.)
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Boris D. Zlatopolskiy
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany; (B.D.Z.); (B.N.)
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Bernd Neumaier
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany; (B.D.Z.); (B.N.)
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
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Abstract
The blood-brain barrier (BBB) is one of the most selective endothelial barriers. An understanding of its cellular, morphological, and biological properties in health and disease is necessary to develop therapeutics that can be transported from blood to brain. In vivo models have provided some insight into these features and transport mechanisms adopted at the brain, yet they have failed as a robust platform for the translation of results into clinical outcomes. In this article, we provide a general overview of major BBB features and describe various models that have been designed to replicate this barrier and neurological pathologies linked with the BBB. We propose several key parameters and design characteristics that can be employed to engineer physiologically relevant models of the blood-brain interface and highlight the need for a consensus in the measurement of fundamental properties of this barrier.
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Affiliation(s)
- Cynthia Hajal
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Baptiste Le Roi
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Roger D Kamm
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Ben M Maoz
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Feng F, Fawcett JP, Zhang H, Tucker IG. Cell-based, animal and H 1 receptor binding studies relative to the sedative effects of ketotifen and norketotifen atropisomers. ACTA ACUST UNITED AC 2020; 72:507-518. [PMID: 32030755 DOI: 10.1111/jphp.13220] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 11/29/2019] [Indexed: 12/01/2022]
Abstract
OBJECTIVES Ketotifen (K) and its active metabolite norketotifen (N) exist as optically active atropisomers. They both have antihistaminic and anti-inflammatory properties but the S-atropisomer of N (SN) causes less sedation than K and RN in rodents. This study investigated whether this could be related to a lower concentration of SN in brain or a lower affinity of SN for rat brain H1 receptors. METHODS Ketotifen and norketotifen atropisomers were quantified using a validated chiral HPLC assay. RBE4 and Caco-2 cell monolayers were used in uptake and permeability studies, respectively. Free and total brain-to-plasma (B/P) ratios were determined after injecting racemic K and N into rat tail veins. Affinity for rat brain H1 receptors (KI ) was determined using the [3 H]mepyramine binding assay. KEY FINDINGS Uptake and permeation studies indicate no stereoselective transport for K or N. B/P ratios reveal the brain concentration of N is lower than K with no stereoselective transport into brain. Finally, the [3 H]mepyramine binding assay shows SN has the lowest affinity for rat brain H1 receptors. CONCLUSION The lower sedative effect of SN in rodents is probably due to a combination of a lower uptake of N than K into the brain and less affinity of SN for CNS H1 receptors.
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Affiliation(s)
- Feifei Feng
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - J Paul Fawcett
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - Hu Zhang
- School of Pharmacy, University of Otago, Dunedin, New Zealand
| | - Ian G Tucker
- School of Pharmacy, University of Otago, Dunedin, New Zealand
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Hajal C, Campisi M, Mattu C, Chiono V, Kamm RD. In vitro models of molecular and nano-particle transport across the blood-brain barrier. BIOMICROFLUIDICS 2018; 12:042213. [PMID: 29887937 PMCID: PMC5980570 DOI: 10.1063/1.5027118] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/09/2018] [Indexed: 05/11/2023]
Abstract
The blood-brain barrier (BBB) is the tightest endothelial barrier in humans. Characterized by the presence of tight endothelial junctions and adherens junctions, the primary function of the BBB is to maintain brain homeostasis through the control of solute transit across the barrier. The specific features of this barrier make for unique modes of transport of solutes, nanoparticles, and cells across the BBB. Understanding the different routes of traffic adopted by each of these is therefore critical in the development of targeted therapies. In an attempt to move towards controlled experimental assays, multiple groups are now opting for the use of microfluidic systems. A comprehensive understanding of bio-transport processes across the BBB in microfluidic devices is therefore necessary to develop targeted and efficient therapies for a host of diseases ranging from neurological disorders to the spread of metastases in the brain.
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Affiliation(s)
- Cynthia Hajal
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 500 Technology Square, MIT Building, Room NE47-321, Cambridge, Massachusetts 02139, USA
| | | | - Clara Mattu
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin, Italy
| | - Valeria Chiono
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin, Italy
| | - Roger D. Kamm
- Author to whom correspondence should be addressed: and
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McRae M, LaFratta LM, Nguyen BM, Paris JJ, Hauser KF, Conway DE. Characterization of cell-cell junction changes associated with the formation of a strong endothelial barrier. Tissue Barriers 2018; 6:e1405774. [PMID: 29388870 DOI: 10.1080/21688370.2017.1405774] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A principal function of endothelial cells is the formation of a barrier between the blood and tissues. This barrier arises from the physical connections at cell-cell junctions, which includes cytoskeletal tight junction and adherens junction proteins. Methods that alter barrier function must therefore affect these cell-cell connections. The blood brain barrier (BBB) represents perhaps the most selective endothelial barrier, which arises from endothelial cell interactions with astrocytes and pericytes. Even in non-central nervous system (CNS) endothelial cells, barrier properties can be enhanced, mimicking the BBB, through induction of intercellular junctions, by either direct co-culture with astrocytes, supplementation with astrocyte conditioned medium (ACM) and/or pharmacologic enhancement of cAMP. To understand how cell-cell junctions change during endothelial barrier enhancement, we examined the effects of ACM and/or cAMP donors added to standard media on human umbilical vein endothelial cells (HUVEC). HUVEC cultured with cAMP-elevating agents had the most enhanced barrier function as measured by Electric Cell-substrate Impedance Sensing (ECIS®), a real-time, label-free, impedance based method of studying cell barrier properties. However, subtle differences in actin and cell-cell junction proteins were seen across all four culture conditions. cAMP-elevating agents also triggered the redistribution of ZO-1 and VE-cadherin to cell-cell junctions, and intensified the actin microfilament network at the cell cortex. Using a VE-cadherin FRET-force sensor, we observed a decrease in VE-cadherin force in HUVEC cultured with ACM with cAMP donors. Our data indicate cAMP elevation induces both junctional strengthening and reduced VE-cadherin forces. Additionally, treatment with an inhibitor of formin, which reduced actin stress fibers, enhanced barrier function. These data suggest that barrier function is modulated both through the trafficking of proteins to cell-cell junctions, and through the modulation and a relaxation of mechanical force through adherens junctions as intercellular junctional complexes become established.
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Affiliation(s)
- MaryPeace McRae
- a Department of Pharmacotherapy and Outcomes Science , School of Pharmacy, Virginia Commonwealth University , Richmond , VA , USA
| | - Lindsay M LaFratta
- b Department of Biomedical Engineering , Virginia Commonwealth University , Richmond , VA , USA
| | - Benjamin M Nguyen
- b Department of Biomedical Engineering , Virginia Commonwealth University , Richmond , VA , USA
| | - Jason J Paris
- c Department of BioMolecular Sciences , School of Pharmacy, University of Mississippi, University , MS , USA
| | - Kurt F Hauser
- d Department of Pharmacology , Virginia Commonwealth University , Richmond , VA , USA
| | - Daniel E Conway
- b Department of Biomedical Engineering , Virginia Commonwealth University , Richmond , VA , USA
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Restin T, Kajdi ME, Schläpfer M, Roth Z’graggen B, Booy C, Dumrese C, Beck-Schimmer B. Sevoflurane protects rat brain endothelial barrier structure and function after hypoxia-reoxygenation injury. PLoS One 2017; 12:e0184973. [PMID: 29023577 PMCID: PMC5638245 DOI: 10.1371/journal.pone.0184973] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2016] [Accepted: 09/05/2017] [Indexed: 12/23/2022] Open
Abstract
Background After cerebral injury blood-brain barrier disruption significantly impairs brain homeostasis. Volatile anesthetics have been shown to be protective in ischemia-reperfusion injury scenarios. Their impact on brain endothelial cells after hypoxia-reoxygenation (H/R) has not yet been studied in detail. Methods Rat brain endothelial cells (RBE4) were exposed to severe hypoxia and reoxygenated in air in the presence or absence of sevoflurane. Changes in dextran permeability and architecture of the cellular junctional proteins ZO-1 and β-catenin were measured. To determine necrosis and apoptosis rate DNA content, LDH release and caspase activity were quantified. The role of vascular endothelial growth factor (VEGF) as an inflammatory mediator increasing vascular permeability was assessed. At the same time, it was evaluated if sevoflurane effects are mediated through VEGF. Results were analyzed by unpaired t-tests or one way-analysis of variance followed by Bonferroni’s correction. Results H/R led to a 172% increase in permeability (p<0.001), cell swelling and qualitatively but not quantitatively modified expression of ZO-1, β-catenin and F-actin. In the presence of sevoflurane during reoxygenation, barrier function improved by 96% (p = 0.042) in parallel to a decrease of the cell size and less re-arranged junction proteins and F-actin. Sevoflurane-induced improvement of the barrier function could not be explained on the level of necrosis or apoptosis as they remained unchanged independent of the presence or absence of the volatile anesthetic. Increased expression of VEGF after H/R was attenuated by sevoflurane by 34% (p = 0.004). Barrier protection provided by sevoflurane was similar to the application of a blocking VEGF-antibody. Furthermore, the protective effect of sevoflurane was abolished in the presence of recombinant VEGF. Conclusions In H/R-induced rat brain endothelial cell injury sevoflurane maintains endothelial barrier function through downregulation of VEGF, which is a key player not only in mediating injury, but also with regard to the protective effect of sevoflurane.
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Affiliation(s)
- Tanja Restin
- Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Marie-Elisabeth Kajdi
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Martin Schläpfer
- Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Birgit Roth Z’graggen
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Christa Booy
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Claudia Dumrese
- Flow Cytometry Facility, University of Zurich, Zurich, Switzerland
| | - Beatrice Beck-Schimmer
- Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland
- Institute of Physiology, Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
- Department of Anesthesiology, University of Illinois at Chicago, Chicago, United States of America
- * E-mail:
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Matrix Metalloproteinase Activity in Infections by an Encephalitic Virus, Mouse Adenovirus Type 1. J Virol 2017; 91:JVI.01412-16. [PMID: 28053109 DOI: 10.1128/jvi.01412-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 12/24/2016] [Indexed: 12/17/2022] Open
Abstract
Mouse adenovirus type 1 (MAV-1) infection causes encephalitis in susceptible strains of mice and alters the permeability of infected brains to small molecules, which indicates disruption of the blood-brain barrier (BBB). Under pathological conditions, matrix metalloproteinases (MMPs) can disrupt the BBB through their proteolytic activity on basement membrane and tight junction proteins. We examined whether MAV-1 infection alters MMP activity in vivo and in vitro Infected MAV-1-susceptible SJL mice had higher MMP2 and MMP9 activity in brains, measured by gelatin zymography, than mock-infected mice. Infected MAV-1-resistant BALB/c mice had MMP activity levels equivalent to those in mock infection. Primary SJL mouse brain endothelial cells (a target of MAV-1 in vivo) infected ex vivo with MAV-1 had no difference in activities of secreted MMP2 and MMP9 from mock cells. We show for the first time that astrocytes and microglia are also infected in vivo by MAV-1. Infected mixed primary cultures of astrocytes and microglia had higher levels of MMP2 and MMP9 activity than mock-infected cells. These results indicate that increased MMP activity in the brains of MAV-1-infected susceptible mice may be due to MMP activity produced by endothelial cells, astrocytes, and microglia, which in turn may contribute to BBB disruption and encephalitis in susceptible mice.IMPORTANCE RNA and DNA viruses can cause encephalitis; in some cases, this is accompanied by MMP-mediated disruption of the BBB. Activated MMPs degrade extracellular matrix and cleave tight-junction proteins and cytokines, modulating their functions. MAV-1 infection of susceptible mice is a tractable small-animal model for encephalitis, and the virus causes disruption of the BBB. We showed that MAV-1 infection increases enzymatic activity of two key MMPs known to be secreted and activated in neuroinflammation, MMP2 and MMP9, in brains of susceptible mice. MAV-1 infects endothelial cells, astrocytes, and microglia, cell types in the neurovascular unit that can secrete MMPs. Ex vivo MAV-1 infection of these cell types caused higher MMP activity than mock infection, suggesting that they may contribute to the higher MMP activity seen in vivo To our knowledge, this provides the first evidence of an encephalitic DNA virus in its natural host causing increased MMP activity in brains.
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Thomsen MS, Birkelund S, Burkhart A, Stensballe A, Moos T. Synthesis and deposition of basement membrane proteins by primary brain capillary endothelial cells in a murine model of the blood-brain barrier. J Neurochem 2016; 140:741-754. [PMID: 27456748 DOI: 10.1111/jnc.13747] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 06/25/2016] [Accepted: 07/20/2016] [Indexed: 11/30/2022]
Abstract
The brain vascular basement membrane is important for both blood-brain barrier (BBB) development, stability, and barrier integrity and the contribution hereto from brain capillary endothelial cells (BCECs), pericytes, and astrocytes of the BBB is probably significant. The aim of this study was to analyse four different in vitro models of the murine BBB for expression and possible secretion of major basement membrane proteins from murine BCECs (mBCECs). mBCECs, pericytes and glial cells (mainly astrocytes and microglia) were prepared from brains of C57BL/6 mice. The mBCECs were grown as monoculture, in co-culture with pericytes or mixed glial cells, or as a triple-culture with both pericytes and mixed glial cells. The integrity of the BBB models was validated by measures of transendothelial electrical resistance (TEER) and passive permeability to mannitol. The expression of basement membrane proteins was analysed using RT-qPCR, mass spectrometry and immunocytochemistry. Co-culturing mBCECs with pericytes, mixed glial cells, or both significantly increased the TEER compared to the monoculture, and a low passive permeability was correlated with high TEER. The mBCECs expressed all major basement membrane proteins such as laminin-411, laminin-511, collagen [α1(IV)]2 α2(IV), agrin, perlecan, and nidogen 1 and 2 in vitro. Increased expression of the laminin α5 subunit correlated with the addition of BBB-inducing factors (hydrocortisone, Ro 20-1724, and pCPT-cAMP), whereas increased expression of collagen IV α1 primarily correlated with increased levels of cAMP. In conclusion, BCECs cultured in vitro coherently form a BBB and express basement membrane proteins as a feature of maturation. Cover Image for this issue: doi: 10.1111/jnc.13789.
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Affiliation(s)
- Maj Schneider Thomsen
- Laboratory of Neurobiology, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Svend Birkelund
- Laboratory of Medical Mass Spectrometry, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Annette Burkhart
- Laboratory of Neurobiology, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Allan Stensballe
- Laboratory of Medical Mass Spectrometry, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Torben Moos
- Laboratory of Neurobiology, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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11
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Immortalized endothelial cell lines for in vitro blood–brain barrier models: A systematic review. Brain Res 2016; 1642:532-545. [DOI: 10.1016/j.brainres.2016.04.024] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 04/05/2016] [Accepted: 04/12/2016] [Indexed: 12/18/2022]
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Aparicio-Blanco J, Martín-Sabroso C, Torres-Suárez AI. In vitro screening of nanomedicines through the blood brain barrier: A critical review. Biomaterials 2016; 103:229-255. [PMID: 27392291 DOI: 10.1016/j.biomaterials.2016.06.051] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/14/2016] [Accepted: 06/20/2016] [Indexed: 12/16/2022]
Abstract
The blood-brain barrier accounts for the high attrition rate of the treatments of most brain disorders, which therefore remain one of the greatest health-care challenges of the twenty first century. Against this background of hindrance to brain delivery, nanomedicine takes advantage of the assembly at the nanoscale of available biomaterials to provide a delivery platform with potential to raising brain levels of either imaging or therapeutic agents. Nevertheless, to prevent later failure due to ineffective drug levels at the target site, researchers have been endeavoring to develop a battery of in vitro screening procedures that can predict earlier in the drug discovery process the ability of these cutting-edge drug delivery platforms to cross the blood-brain barrier for biomedical purposes. This review provides an in-depth analysis of the currently available in vitro blood-brain barrier models (both cell-based and non-cell-based) with the focus on their suitability for understanding the biological brain distribution of forthcoming nanomedicines. The relationship between experimental factors and underlying physiological assumptions that would ultimately lead to a more predictive capacity of their in vivo performance, and those methods already assayed for the evaluation of the brain distribution of nanomedicines are comprehensively discussed.
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Affiliation(s)
- Juan Aparicio-Blanco
- Department of Pharmaceutical Technology, Faculty of Pharmacy, Complutense University, 28040, Madrid, Spain
| | - Cristina Martín-Sabroso
- Department of Pharmaceutical Technology, Faculty of Pharmacy, Complutense University, 28040, Madrid, Spain
| | - Ana-Isabel Torres-Suárez
- Department of Pharmaceutical Technology, Faculty of Pharmacy, Complutense University, 28040, Madrid, Spain; University Institute of Industrial Pharmacy, Complutense University, 28040, Madrid, Spain.
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Kułakowska A, Byfield FJ, Zendzian-Piotrowska M, Zajkowska JM, Drozdowski W, Mroczko B, Janmey PA, Bucki R. Increased levels of sphingosine-1-phosphate in cerebrospinal fluid of patients diagnosed with tick-borne encephalitis. J Neuroinflammation 2014; 11:193. [PMID: 25421616 PMCID: PMC4258275 DOI: 10.1186/s12974-014-0193-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 11/02/2014] [Indexed: 12/21/2022] Open
Abstract
Background Tick-borne encephalitis (TBE) is a serious acute central nervous system infection that can result in death or long-term neurological dysfunctions. We hypothesize that changes in sphingosine-1-phosphate (S1P) concentration occur during TBE development. Methods S1P and interleukin-6 (IL-6) concentrations in blood plasma and cerebrospinal fluid (CSF) were measured using HPLC and ELISA, respectively. The effects of S1P on cytoskeletal structure and IL-6 production were assessed using rat astrocyte primary cultures with and without addition of plasma gelsolin and the S1P receptor antagonist fingolimod phosphate (FTY720P). Results We report that acute inflammation due to TBE virus infection is associated with elevated levels of S1P and IL-6 in the CSF of infected patients. This elevated concentration is observed even at the earliest neurologic stage of disease, and may be controlled by glucocorticosteroid anti-inflammatory treatment, administered to patients unresponsive to antipyretic drugs and who suffer from a fever above 39°C. In vitro, treatment of confluent rat astrocyte monolayers with a high concentration of S1P (5 μM) results in cytoskeletal actin remodeling that can be prevented by the addition of recombinant plasma gelsolin, FTY720P, or their combination. Additionally, gelsolin and FTY720P significantly decreased S1P-induced release of IL-6. Conclusions TBE is associated with increased concentration of S1P and IL-6 in CSF, and this increase might promote development of inflammation. The consequences of increased extracellular S1P can be modulated by gelsolin and FTY720P. Therefore, blocking the inflammatory response at sites of infection by agents modulating S1P pathways might aid in developing new strategies for TBE treatment.
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Al-Shehri A, Favretto ME, Ioannou PV, Romero IA, Couraud PO, Weksler BB, Parker TL, Kallinteri P. Permeability of PEGylated Immunoarsonoliposomes Through In Vitro Blood Brain Barrier-Medulloblastoma Co-culture Models for Brain Tumor Therapy. Pharm Res 2014; 32:1072-83. [DOI: 10.1007/s11095-014-1519-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 09/12/2014] [Indexed: 10/24/2022]
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15
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Chen RL, Ogunshola OO, Yeoh KK, Jani A, Papadakis M, Nagel S, Schofield CJ, Buchan AM. HIF prolyl hydroxylase inhibition prior to transient focal cerebral ischaemia is neuroprotective in mice. J Neurochem 2014; 131:177-89. [PMID: 24974727 DOI: 10.1111/jnc.12804] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Revised: 06/19/2014] [Accepted: 06/23/2014] [Indexed: 12/17/2022]
Abstract
This study investigated the effects of 2-(1-chloro-4-hydroxyisoquinoline-3-carboxamido) acetic acid (IOX3), a selective small molecule inhibitor of hypoxia-inducible factor (HIF) prolyl hydroxylases, on mouse brains subject to transient focal cerebral ischaemia. Male, 8- to 12-week-old C57/B6 mice were subjected to 45 min of middle cerebral artery occlusion (MCAO) either immediately or 24 h after receiving IOX3. Mice receiving IOX3 at 20 mg/kg 24 h prior to the MCAO had better neuroscores and smaller blood-brain barrier (BBB) disruption and infarct volumes than mice receiving the vehicle, whereas those having IOX3 at 60 mg/kg showed no significant changes. IOX3 treatment immediately before MCAO was not neuroprotective. IOX3 up-regulated HIF-1α, and increased EPO expression in mouse brains. In an in vitro BBB model (RBE4 cell line), IOX3 up-regulated HIF-1α and delocalized ZO-1. Pre-treating IOX3 on RBE4 cells 24 h before oxygen-glucose deprivation had a protective effect on endothelial barrier preservation with ZO-1 being better localized, while immediate IOX3 treatment did not. Our study suggests that HIF stabilization with IOX3 before cerebral ischaemia is neuroprotective partially because of BBB protection, while immediate application could be detrimental. These results provide information for studies aimed at the therapeutic activation of HIF pathway for neurovascular protection from cerebral ischaemia. We show that IOX3, a selective small molecule (280.66 Da) HIF prolyl hydroxylase inhibitor, could up-regulate HIF-1α and increase erythropoietin expression in mice. We further demonstrate that HIF stabilization with IOX3 before cerebral ischaemia is neuroprotective partially because of blood-brain barrier (BBB) protection, while immediate application is detrimental both in vivo and in vitro. These findings provide new insights into the role of HIF stabilization in ischaemic stroke.
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Affiliation(s)
- Ruoli L Chen
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.,Institute for Science and Technology in Medicine, School of Pharmacy, Keele University, Staffordshire, UK
| | - O O Ogunshola
- Institute of Veterinary Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Karkheng K Yeoh
- Chemistry Research Laboratory, University of Oxford, Oxford, UK
| | - Anant Jani
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Michalis Papadakis
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Simon Nagel
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.,Department of Neurology, University of Heidelberg, Heidelberg, Germany
| | | | - Alastair M Buchan
- Acute Stroke Programme, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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16
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Affiliation(s)
- Yarong He
- From the Emergency Department, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China (Y.H., Y.C.); Laboratory of Neurobiology and Genetics, The Rockefeller University, New York, NY (Y.Y.); and Department of Pharmacological Sciences, Stony Brook University, NY (S.E.T.)
| | - Yao Yao
- From the Emergency Department, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China (Y.H., Y.C.); Laboratory of Neurobiology and Genetics, The Rockefeller University, New York, NY (Y.Y.); and Department of Pharmacological Sciences, Stony Brook University, NY (S.E.T.)
| | - Stella E Tsirka
- From the Emergency Department, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China (Y.H., Y.C.); Laboratory of Neurobiology and Genetics, The Rockefeller University, New York, NY (Y.Y.); and Department of Pharmacological Sciences, Stony Brook University, NY (S.E.T.)
| | - Yu Cao
- From the Emergency Department, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China (Y.H., Y.C.); Laboratory of Neurobiology and Genetics, The Rockefeller University, New York, NY (Y.Y.); and Department of Pharmacological Sciences, Stony Brook University, NY (S.E.T.).
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17
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Quinn M, McMillin M, Galindo C, Frampton G, Pae HY, DeMorrow S. Bile acids permeabilize the blood brain barrier after bile duct ligation in rats via Rac1-dependent mechanisms. Dig Liver Dis 2014; 46:527-34. [PMID: 24629820 PMCID: PMC4065628 DOI: 10.1016/j.dld.2014.01.159] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/10/2014] [Accepted: 01/28/2014] [Indexed: 02/08/2023]
Abstract
BACKGROUND The blood brain barrier tightly regulates the passage of molecules into the brain and becomes leaky following obstructive cholestasis. The aim of this study was to determine if increased serum bile acids observed during cholestasis permeabilize the blood brain barrier. METHODS Rats underwent bile duct ligation or deoxycholic or chenodeoxycholic acid injections and blood brain barrier permeability assessed. In vitro, the permeability of rat brain microvessel endothelial cell monolayers, the expression and phosphorylation of occludin, ZO-1 and ZO-2 as well as the activity of Rac1 was assessed after treatment with plasma from cholestatic rats, or bile acid treatment, in the presence of a Rac1 inhibitor. RESULTS Blood brain barrier permeability was increased in vivo and in vitro following bile duct ligation or treatment with bile acids. Associated with the bile acid-stimulated increase in endothelial cell monolayer permeability was elevated Rac1 activity and increased phosphorylation of occludin. Pretreatment of endothelial cell monolayers with a Rac1 inhibitor prevented the effects of bile acid treatment on occludin phosphorylation and monolayer permeability. CONCLUSIONS These data suggest that increased circulating serum bile acids may contribute to the increased permeability of the blood brain barrier seen during obstructive cholestasis via disruption of tight junctions.
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Affiliation(s)
- Matthew Quinn
- Department of Internal Medicine, Texas A&M Health Science Center College of Medicine, Temple, Texas, USA
| | - Matthew McMillin
- Department of Internal Medicine, Texas A&M Health Science Center College of Medicine, Temple, Texas, USA
| | - Cheryl Galindo
- Department of Internal Medicine, Texas A&M Health Science Center College of Medicine, Temple, Texas, USA
| | - Gabriel Frampton
- Department of Internal Medicine, Texas A&M Health Science Center College of Medicine, Temple, Texas, USA
| | - Hae Yong Pae
- Department of Internal Medicine, Texas A&M Health Science Center College of Medicine, Temple, Texas, USA
| | - Sharon DeMorrow
- Department of Internal Medicine, Texas A&M Health Science Center College of Medicine, Temple, Texas, USA,Digestive Disease Research Center, Scott & White Hospital, Temple, Texas, USA,Central Texas Veterans Health Care System, Temple, Texas, USA
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18
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Engelhardt S, Patkar S, Ogunshola OO. Cell-specific blood-brain barrier regulation in health and disease: a focus on hypoxia. Br J Pharmacol 2014; 171:1210-30. [PMID: 24641185 PMCID: PMC3952799 DOI: 10.1111/bph.12489] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/02/2013] [Accepted: 10/16/2013] [Indexed: 01/16/2023] Open
Abstract
The blood-brain barrier (BBB) is a complex vascular structure consisting of microvascular endothelial cells that line the vessel wall, astrocyte end-feet, pericytes, as well as the basal lamina. BBB cells act in concert to maintain the characteristic impermeable and low paracellular flux of the brain vascular network, thus ensuring a homeostatic neuronal environment. Alterations in BBB stability that occur during injury have dire consequences on disease progression and it is clear that BBB cell-specific responses, positive or negative, must make a significant contribution to injury outcome. Reduced oxygenation, or hypoxia, is a characteristic of many brain diseases that significantly increases barrier permeability. Recent data suggest that hypoxia-inducible factor (HIF-1), the master regulator of the hypoxic response, probably mediates many hypoxic effects either directly or indirectly via its target genes. This review discusses current knowledge of physiological cell-specific regulation of barrier function, their responses to hypoxia as well as consequences of hypoxic- and HIF-1-mediated mechanisms on barrier integrity during select brain diseases. In the final sections, the potential of current advances in targeting HIF-1 as a therapeutic strategy will be overviewed.
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Affiliation(s)
- S Engelhardt
- Institute of Veterinary Physiology, University of ZurichZurich, Switzerland
| | - S Patkar
- Institute of Veterinary Physiology, University of ZurichZurich, Switzerland
| | - O O Ogunshola
- Institute of Veterinary Physiology, University of ZurichZurich, Switzerland
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19
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Bertini G, Bramanti P, Constantin G, Pellitteri M, Radu BM, Radu M, Fabene PF. New players in the neurovascular unit: insights from experimental and clinical epilepsy. Neurochem Int 2013; 63:652-9. [PMID: 23962437 DOI: 10.1016/j.neuint.2013.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 07/26/2013] [Accepted: 08/01/2013] [Indexed: 01/12/2023]
Abstract
The conventional notion that neurons are exclusively responsible for brain signaling is increasingly challenged by the idea that brain function in fact depends on a complex interplay between neurons, glial cells, vascular endothelium, and immune-related blood cells. Recent data demonstrates that neuronal activity is profoundly affected by an entire cellular and extracellular 'orchestra', the so-called neurovascular unit (NVU). Among the 'musical instruments' of this orchestra, there may be molecules long-known in biomedicine as important mediators of inflammatory and immune responses in the organism, as well as non-neuronal cells, e.g., leukocytes. We here review recent evidence on the structure and function of the NVU, both in the healthy brain and in pathological conditions, such as the abnormal NVU activation observed in epilepsy. We will argue that a better understanding of NVU function will require the addition of new players to the 'orchestra'.
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Affiliation(s)
- Giuseppe Bertini
- Department of Neurological and Movement Sciences, Section of Anatomy and Histology, University of Verona, Strada Le Grazie 8, Verona 37134, Italy
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20
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Passeleu-Le Bourdonnec C, Carrupt PA, Scherrmann JM, Martel S. Methodologies to assess drug permeation through the blood-brain barrier for pharmaceutical research. Pharm Res 2013; 30:2729-56. [PMID: 23801086 DOI: 10.1007/s11095-013-1119-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 06/11/2013] [Indexed: 12/21/2022]
Abstract
The drug discovery process for drugs that target the central nervous system suffers from a very high rate of failure due to the presence of the blood-brain barrier, which limits the entry of xenobiotics into the brain. To minimise drug failure at different stages of the drug development process, new methodologies have been developed to understand the absorption, distribution, metabolism, excretion and toxicity (ADMET) profile of drug candidates at early stages of drug development. Additionally, understanding the permeation of drug candidates is also important, particularly for drugs that target the central nervous system. During the first stages of the drug discovery process, in vitro methods that allow for the determination of permeability using high-throughput screening methods are advantageous. For example, performing the parallel artificial membrane permeability assay followed by cell-based models with interesting hits is a useful technique for identifying potential drugs. In silico models also provide interesting information but must be confirmed by in vitro models. Finally, in vivo models, such as in situ brain perfusion, should be studied to reduce a large number of drug candidates to a few lead compounds. This article reviews the different methodologies used in the drug discovery and drug development processes to determine the permeation of drug candidates through the blood-brain barrier.
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Affiliation(s)
- Céline Passeleu-Le Bourdonnec
- School of Pharmaceutical Sciences, University of Geneva University of Lausanne, Quai Ernest Ansermet 30, 1211, Geneva, Switzerland
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21
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Achyuta AKH, Conway AJ, Crouse RB, Bannister EC, Lee RN, Katnik CP, Behensky AA, Cuevas J, Sundaram SS. A modular approach to create a neurovascular unit-on-a-chip. LAB ON A CHIP 2013; 13:542-53. [PMID: 23108480 DOI: 10.1039/c2lc41033h] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In this work, we describe the fabrication and working of a modular microsystem that recapitulates the functions of the "Neurovascular Unit". The microdevice comprised a vertical stack of a poly(dimethylsiloxane) (PDMS) neural parenchymal chamber separated by a vascular channel via a microporous polycarbonate (PC) membrane. The neural chamber housed a mixture of neurons (~4%), astrocytes (~95%), and microglia (~1%). The vascular channel was lined with a layer of rat brain microvascular endothelial cell line (RBE4). Cellular components in the neural chamber and vascular channel showed viability (>90%). The neural cells fired inhibitory as well as excitatory potentials following 10 days of culture. The endothelial cells showed diluted-acetylated low density lipoprotein (dil-a-LDL) uptake, expressed von Willebrand factor (vWF) and zonula occludens (ZO-1) tight junctions, and showed decreased Alexafluor™-conjugated dextran leakage across their barriers significantly compared with controls (p < 0.05). When the vascular layer was stimulated with TNF-α for 6 h, about 75% of resident microglia and astrocytes on the neural side were activated significantly (p < 0.05 compared to controls) recapitulating tissue-mimetic responses resembling neuroinflammation. The impact of this microsystem lies in the fact that this biomimetic neurovascular platform might not only be harnessed for obtaining mechanistic insights for neurodegenerative disorders, but could also serve as a potential screening tool for central nervous system (CNS) therapeutics in toxicology and neuroinfectious diseases.
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Affiliation(s)
- Anil Kumar H Achyuta
- The Charles Stark Draper Laboratory, Bioengineering Center, 3802 Spectrum Blvd. Suite 201, Tampa, FL, USA.
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22
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Modeling the blood-brain barrier using stem cell sources. Fluids Barriers CNS 2013; 10:2. [PMID: 23305164 PMCID: PMC3564868 DOI: 10.1186/2045-8118-10-2] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 11/13/2012] [Indexed: 12/18/2022] Open
Abstract
The blood–brain barrier (BBB) is a selective endothelial interface that controls trafficking between the bloodstream and brain interstitial space. During development, the BBB arises as a result of complex multicellular interactions between immature endothelial cells and neural progenitors, neurons, radial glia, and pericytes. As the brain develops, astrocytes and pericytes further contribute to BBB induction and maintenance of the BBB phenotype. Because BBB development, maintenance, and disease states are difficult and time-consuming to study in vivo, researchers often utilize in vitro models for simplified analyses and higher throughput. The in vitro format also provides a platform for screening brain-penetrating therapeutics. However, BBB models derived from adult tissue, especially human sources, have been hampered by limited cell availability and model fidelity. Furthermore, BBB endothelium is very difficult if not impossible to isolate from embryonic animal or human brain, restricting capabilities to model BBB development in vitro. In an effort to address some of these shortcomings, advances in stem cell research have recently been leveraged for improving our understanding of BBB development and function. Stem cells, which are defined by their capacity to expand by self-renewal, can be coaxed to form various somatic cell types and could in principle be very attractive for BBB modeling applications. In this review, we will describe how neural progenitor cells (NPCs), the in vitro precursors to neurons, astrocytes, and oligodendrocytes, can be used to study BBB induction. Next, we will detail how these same NPCs can be differentiated to more mature populations of neurons and astrocytes and profile their use in co-culture modeling of the adult BBB. Finally, we will describe our recent efforts in differentiating human pluripotent stem cells (hPSCs) to endothelial cells with robust BBB characteristics and detail how these cells could ultimately be used to study BBB development and maintenance, to model neurological disease, and to screen neuropharmaceuticals.
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23
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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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Abstract
The brain is one of the most protected organs in the body. There are two key barriers that control the access of endogenous substances and xenobiotics (drugs or toxins) to the CNS. These physiological structures are the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier. The BBB represents the main determinant of the effective delivery of drugs to the CNS. Good access through the BBB is essential if the target site is located within the CNS or, in contrast, can be a disadvantage if adverse reactions occur at central level. The development of new drugs targeted to the CNS requires a better knowledge of the factors affecting BBB permeation as well as in vitro and in silico predictive tools to optimize screening, and to reduce the attrition rate at later stages of drug development. This review discusses the particular characteristics of the biology and physiology of the BBB with respect to the permeation and distribution of drugs into the brain. The factors affecting rate, extent and distribution into the brain are discussed and a brief description of the in silico, in vitro, in situ and in vivo methods used to measure BBB transport are presented. Finally, the lastest proposals and strategies to enhance transport across the BBB of new CNS drugs are summarized.
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25
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The role of amino acid transporters in GSH synthesis in the blood-brain barrier and central nervous system. Neurochem Int 2012; 61:405-14. [PMID: 22634224 DOI: 10.1016/j.neuint.2012.05.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 04/17/2012] [Accepted: 05/15/2012] [Indexed: 12/22/2022]
Abstract
Glutathione (GSH) plays a critical role in protecting cells from oxidative stress and xenobiotics, as well as maintaining the thiol redox state, most notably in the central nervous system (CNS). GSH concentration and synthesis are highly regulated within the CNS and are limited by availability of the sulfhydryl amino acid (AA) l-cys, which is mainly transported from the blood, through the blood-brain barrier (BBB), and into neurons. Several antiporter transport systems (e.g., x(c)(-), x(-)(AG), and L) with clearly different luminal and abluminal distribution, Na(+), and pH dependency have been described in brain endothelial cells (BEC) of the BBB, as well as in neurons, astrocytes, microglia and oligodendrocytes from different brain structures. The purpose of this review is to summarize information regarding the different AA transport systems for l-cys and its oxidized form l-cys(2) in the CNS, such as expression and activity in blood-brain barrier endothelial cells, astrocytes and neurons and environmental factors that modulate transport kinetics.
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26
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Kuo TY, Huang CL, Yang JM, Huang WJ, Huang NK, Chen YW, Lin RJ, Yang YC. The role of ribosylated-BSA in regulating PC12 cell viability. Cell Biol Toxicol 2012; 28:255-67. [DOI: 10.1007/s10565-012-9220-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2011] [Accepted: 04/13/2012] [Indexed: 01/06/2023]
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27
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Wang L, Li Q, Du J, Chen B, Li Q, Huang X, Guo X, Huang Q. Advanced glycation end products induce moesin phosphorylation in murine retinal endothelium. Acta Diabetol 2012; 49:47-55. [PMID: 21327982 DOI: 10.1007/s00592-011-0267-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 02/02/2011] [Indexed: 12/20/2022]
Abstract
Increase in vascular permeability is the most important pathological event during the development of diabetic retinopathy. Deposition of advanced glycation end products (AGEs) plays a crucial role in the process of diabetes. This study was to investigate the role of moesin and its underlying signal transduction in retinal vascular hyper-permeability induced by AGE-modified mouse serum albumin (AGE-MSA). Female C57BL/6 mice were used to produce an AGE-treated model by intraperitoneal administration of AGE-MSA for seven consecutive days. The inner blood-retinal barrier was quantified by Evans blue leakage assay. Endothelial F-actin cytoskeleton in retinal vasculature was visualized by fluorescence probe staining. The expression and phosphorylation of moesin in retinal vessels were detected by RT-PCR and western blotting. Further studies were performed to explore the effects of Rho kinase (ROCK) and p38 MAPK pathway on the involvement of moesin in AGE-induced retinal vascular hyper-permeability response. Treatment with AGE-MSA significantly increased the permeability of the retinal microvessels and induced the disorganization of F-actin in retinal vascular endothelial cells. The threonine (T558) phosphorylation of moesin in retinal vessels was enhanced remarkably after AGE administration. The phosphorylation of moesin was attenuated by inhibitions of ROCK and p38 MAPK, while this treatment also prevented the dysfunction of inner blood-retinal barrier and the reorganization of F-actin in retinal vascular endothelial cells. These results demonstrate that moesin is involved in AGE-induced retinal vascular endothelial dysfunction and the phosphorylation of moesin is triggered via ROCK and p38 MAPK activation.
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Affiliation(s)
- Lingjun Wang
- Department of Pathophysiology, Key Lab for Shock and Microcirculation Research, Southern Medical University, Tonghe, Guangzhou, People's Republic of China
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28
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Abstract
The chapter provides an introduction and brief overview of currently available in vitro blood-brain barrier models, pointing out the major advantages and disadvantages of the respective models and potential applications. Bovine brain microvessel endothelial cell isolation, culture, and transendothelial permeability measurement procedures are discussed in detail as a model system for a laboratory to begin brain vascular investigations.
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Affiliation(s)
- Kaushik K Shah
- School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
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29
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Naik P, Cucullo L. In vitro blood-brain barrier models: current and perspective technologies. J Pharm Sci 2011; 101:1337-54. [PMID: 22213383 DOI: 10.1002/jps.23022] [Citation(s) in RCA: 181] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Revised: 11/21/2011] [Accepted: 12/01/2011] [Indexed: 01/22/2023]
Abstract
Even in the 21st century, studies aimed at characterizing the pathological paradigms associated with the development and progression of central nervous system diseases are primarily performed in laboratory animals. However, limited translational significance, high cost, and labor to develop the appropriate model (e.g., transgenic or inbred strains) have favored parallel in vitro approaches. In vitro models are of particular interest for cerebrovascular studies of the blood-brain barrier (BBB), which plays a critical role in maintaining the brain homeostasis and neuronal functions. Because the BBB dynamically responds to many events associated with rheological and systemic impairments (e.g., hypoperfusion), including the exposure of potentially harmful xenobiotics, the development of more sophisticated artificial systems capable of replicating the vascular properties of the brain microcapillaries are becoming a major focus in basic, translational, and pharmaceutical research. In vitro BBB models are valuable and easy to use supporting tools that can precede and complement animal and human studies. In this article, we provide a detailed review and analysis of currently available in vitro BBB models ranging from static culture systems to the most advanced flow-based and three-dimensional coculture apparatus. We also discuss recent and perspective developments in this ever expanding research field.
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Affiliation(s)
- Pooja Naik
- Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, Texas 79106, USA
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30
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AL-BADER MD, MALATIALI SA, REDZIC ZB. Expression of Estrogen Receptor α and β in Rat Astrocytes in Primary Culture: Effects of Hypoxia and Glucose Deprivation. Physiol Res 2011; 60:951-60. [DOI: 10.33549/physiolres.932167] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Estrogen replacement therapy could play a role in the reduction of injury associated with cerebral ischemia in vivo, which could be, at least partially, a consequence of estrogen influence of glutamate buffering by astrocytes during hypoxia/ischemia. Estrogen exerts biological effects through interaction with its two receptors: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), which are both expressed in astrocytes. This study explored effects of hypoxia and glucose deprivation (HGD), alone or followed by 1 h recovery, on ERα and ERβ expression in primary rat astrocyte cultures following 1 h exposure to: a) 5 % CO2 in air (control group-CG); b) 2 % O2/5 % CO2 in N2 with glucose deprivation (HGD group-HGDG); or c) the HGDG protocol followed by 1 h CG protocol (recovery group-RG). ERα mRNA expression decreased in HGDG. At the protein level, full-length ERα (67 kDa) and three ERα-immunoreactive protein bands (63, 60 and 52 kDa) were detected. A significant decrease in the 52 kDa band was seen in HGDG, while a significant decrease in expression of the full length ERα was seen in the RG. ERβ mRNA and protein expression (a 54 kDa single band) did not change. The observed decrease in ERα protein may limit estrogen-mediated signalling in astrocytes during hypoxia and recovery.
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Affiliation(s)
| | | | - Z. B. REDZIC
- Department of Physiology, Faculty of Medicine, Kuwait University, Kuwait
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31
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Yang L, Zhang H, Fawcett JP, Mikov M, Tucker IG. Effect of bile salts on the transport of morphine-6-glucuronide in rat brain endothelial cells. J Pharm Sci 2010; 100:1516-24. [PMID: 24081474 DOI: 10.1002/jps.22390] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 09/06/2010] [Accepted: 09/30/2010] [Indexed: 11/09/2022]
Abstract
Bile salts are known to enhance the permeability of biological barriers but little is known about their effects on drug permeability across the blood-brain barrier (BBB). In this paper, the rat brain endothelial 4 (RBE4) cell monolayer incubated with astrocyte-conditioned medium was used as an in vitro model of the BBB to investigate the effects of cholate (C), 12-monoketocholate (MKC), deoxycholate (DC), and taurocholate (TC) on the transport of the hydrophilic drug, morphine-6-glucuronide (M6G). C, MKC, and TC at a concentration of 5 mM each and DC at 1 mM increased the permeability of M6G through the paracellular pathway based on a similar permeability pattern to that of sucrose. RBE4 cell uptake of M6G was unaffected by 5 mM C and TC, whereas 1 mM DC dramatically increased it due to an effect shown to be cytotoxicity as measured by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. Surprisingly, 1 mM MKC significantly increased M6G uptake without any cytotoxicity. In summary, all bile salts increased paracellular permeation of M6G but MKC also enhanced transcellular transport with little cytotoxicity. MKC appears to have the potential to modulate biophysical properties of the cell membrane or membrane-bound transporters and may therefore enhance drug delivery to the brain.
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Affiliation(s)
- Lin Yang
- School of Pharmacy, University of Otago, Dunedin, New Zealand.
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32
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Beese M, Wyss K, Haubitz M, Kirsch T. Effect of cAMP derivates on assembly and maintenance of tight junctions in human umbilical vein endothelial cells. BMC Cell Biol 2010; 11:68. [PMID: 20822540 PMCID: PMC2941681 DOI: 10.1186/1471-2121-11-68] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Accepted: 09/07/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Endothelial tight and adherens junctions control a variety of physiological processes like adhesion, paracellular transport of solutes or trafficking of activated leukocytes. Formation and maintenance of endothelial junctions largely depend on the microenvironment of the specific vascular bed and on interactions of the endothelium with adjacent cell types. Consequently, primary cultures of endothelial cells often lose their specific junctional pattern and fail to establish tight monolayer in vitro. This is also true for endothelial cells isolated from the vein of human umbilical cords (HUVEC) which are widely used as model for endothelial cell-related studies. RESULTS We here compared the effect of cyclic 3'-5'-adenosine monophosphate (cAMP) and its derivates on formation and stabilization of tight junctions and on alterations in paracellular permeability in HUVEC. We demonstrated by light and confocal laser microscopy that for shorter time periods the sodium salt of 8-bromoadenosine-cAMP (8-Br-cAMP/Na) and for longer incubation periods 8-(4-chlorophenylthio)-cAMP (pCPT-cAMP) exerted the greatest effects of all compounds tested here on formation of continuous tight junction strands in HUVEC. We further demonstrated that although all compounds induced protein kinase A-dependent expression of the tight junction proteins claudin-5 and occludin only pCPT-cAMP slightly enhanced paracellular barrier functions. Moreover, we showed that pCPT-cAMP and 8-Br-cAMP/Na induced expression and membrane translocation of tricellulin. CONCLUSIONS pCPT-cAMP and, to a lesser extend, 8-Br-cAMP/Na improved formation of continuous tight junction strands and decreased paracellular permeability in primary HUVEC. We concluded that under these conditions HUVEC represent a feasible in vitro model to study formation and disassembly of endothelial tight junctions and to characterize tight junction-associated proteins.
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Affiliation(s)
- Michaela Beese
- Division of Nephrology, Department of Internal Medicine, Hannover Medical School, Carl-Neuberg-Str 1, 30625 Hannover, Germany
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33
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Esch MB, Sung JH, Shuler ML. Promises, challenges and future directions of μCCAs. J Biotechnol 2010; 148:64-9. [DOI: 10.1016/j.jbiotec.2010.02.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 02/17/2010] [Accepted: 02/22/2010] [Indexed: 10/19/2022]
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34
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Redzic ZB, Malatiali SA, Al-Bader M, Al-Sarraf H. Effects of hypoxia, glucose deprivation and recovery on the expression of nucleoside transporters and adenosine uptake in primary culture of rat cortical astrocytes. Neurochem Res 2010; 35:1434-44. [PMID: 20577800 DOI: 10.1007/s11064-010-0203-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2010] [Indexed: 01/16/2023]
Abstract
The aim of this study was to explore effects of hypoxia, glucose deprivation (HGD) and recovery on expression and activities of equilibrative nucleoside transporters (rENT) and concentrative nucleoside transporters (rCNT) in rat astrocytes in primary culture. Amounts of cellular ATP in the control group (CG, 5% CO(2) in air, medium containing 7 mM D-glucose, 1 mM Na(+)-pyruvate, 1 h), HGD group (2% O(2)/5% CO(2) in N(2), pyruvate-free medium containing 1.5 mM D-glucose and 10 mM 2-deoxy-D-glucose, 1 h) and recovery group (RG, HGD for 1 h, followed by 1 h exposure to the same conditions as the CG) were (nmol/mg protein, n = 4) 18 +/- 1.6, 4.9 +/- 0.6 and 10.1 +/- 0.8, respectively. Extracellular adenosine concentrations increased from (nM, n = 3) 42 +/- 4 in the CG, to 99 +/- 8 in the HGD group and 86 +/- 3 in the RG. Real-time PCR and immunoblotting revealed that in the HGD group and RG, the amounts of rENT1 mRNA and protein were reduced to 40 and 50%, when compared to the CG, respectively. Astrocyte cultures took up [(3)H]adenosine by concentrative and equilibrative transport processes; however, rENT1-mediated uptake was absent in the RG and cultures from the RG took up significantly less [(3)H]adenosine by equilibrative mechanisms than cultures from the CG.
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Affiliation(s)
- Zoran B Redzic
- Department of Physiology, Faculty of Medicine, Kuwait University, Safat, Kuwait.
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35
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dos Santos APM, Milatovic D, Au C, Yin Z, Batoreu MCC, Aschner M. Rat brain endothelial cells are a target of manganese toxicity. Brain Res 2010; 1326:152-61. [PMID: 20170646 DOI: 10.1016/j.brainres.2010.02.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 01/30/2010] [Accepted: 02/04/2010] [Indexed: 12/17/2022]
Abstract
Manganese (Mn) is an essential trace metal; however, exposure to high Mn levels can result in neurodegenerative changes resembling Parkinson's disease (PD). Information on Mn's effects on endothelial cells of the blood-brain barrier (BBB) is lacking. Accordingly, we tested the hypothesis that BBB endothelial cells are a primary target for Mn-induced neurotoxicity. The studies were conducted in an in vitro BBB model of immortalized rat brain endothelial (RBE4) cells. ROS production was determined by F(2)-isoprostane (F(2)-IsoPs) measurement. The relationship between Mn toxicity and redox status was investigated upon intracellular glutathione (GSH) depletion with diethylmaleate (DEM) or L-buthionine sulfoximine (BSO). Mn exposure (200 or 800 microM MnCl(2) or MnSO(4)) for 4 or 24h led to significant decrease in cell viability vs. controls. DEM or BSO pre-treatment led to further enhancement in cytotoxicity vs. exposure to Mn alone, with more pronounced cell death after 24-h DEM pre-treatment. F(2)-IsoPs levels in cells exposed to MnCl(2) (200 or 800 microM) were significantly increased after 4h and remained elevated 24h after exposure compared with controls. Consistent with the effects on cell viability and F(2)-IsoPs, treatment with MnCl(2) (200 or 800 microM) was also associated with a significant decrease in membrane potential. This effect was more pronounced in cells exposed to DEM plus MnCl(2) vs. cells exposed to Mn alone. We conclude that Mn induces direct injury to mitochondria in RBE4 cells. The ensuing impairment in energy metabolism and redox status may modify the restrictive properties of the BBB compromising its function.
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36
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Mensch J, Oyarzabal J, Mackie C, Augustijns P. In vivo, in vitro and in silico methods for small molecule transfer across the BBB. J Pharm Sci 2009; 98:4429-68. [DOI: 10.1002/jps.21745] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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37
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Al Ahmad A, Gassmann M, Ogunshola O. Maintaining blood-brain barrier integrity: Pericytes perform better than astrocytes during prolonged oxygen deprivation. J Cell Physiol 2009; 218:612-22. [DOI: 10.1002/jcp.21638] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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38
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Pottiez G, Sevin E, Cecchelli R, Karamanos Y, Flahaut C. Actin, gelsolin and filamin-A are dynamic actors in the cytoskeleton remodelling contributing to the blood brain barrier phenotype. Proteomics 2009; 9:1207-19. [DOI: 10.1002/pmic.200800503] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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39
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Poller B, Gutmann H, Krähenbühl S, Weksler B, Romero I, Couraud PO, Tuffin G, Drewe J, Huwyler J. The human brain endothelial cell line hCMEC/D3 as a human blood-brain barrier model for drug transport studies. J Neurochem 2008; 107:1358-68. [PMID: 19013850 DOI: 10.1111/j.1471-4159.2008.05730.x] [Citation(s) in RCA: 220] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The human brain endothelial capillary cell line hCMEC/D3 has been developed recently as a model for the human blood-brain barrier. In this study a further characterization of this model was performed with special emphasis on permeability properties and active drug transport. Para- or transcellular permeabilities (P(e)) of inulin (0.74 x 10(-3) cm/min), sucrose (1.60 x 10(-3) cm/min), lucifer yellow (1.33 x 10(-3) cm/min), morphine (5.36 x 10(-3) cm/min), propranolol (4.49 x 10(-3) cm/min) and midazolam (5.13 x 10(-3) cm/min) were measured. By addition of human serum the passive permeability of sucrose could be reduced significantly by up to 39%. Furthermore, the expression of a variety of drug transporters (ABCB1, ABCG2, ABCC1-5) as well as the human transferrin receptor was demonstrated on the mRNA level. ABCB1, ABCG2 and transferrin receptor proteins were detected and functional activity of ABCB1, ABCG2 and the ABCC family was quantified in efflux experiments. Furthermore, ABCB1-mediated bidirectional transport of rhodamine 123 was studied. The transport rate from the apical to the basolateral compartment was significantly lower than that in the inverse direction, indicating directed p-glycoprotein transport. The results of this study demonstrate the usefulness of the hCMEC/D3 cell line as an in vitro model to study drug transport at the level of the human blood-brain barrier.
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Affiliation(s)
- Birk Poller
- Department of Clinical Pharmacology and Toxicology, University Hospital of Basel, Basel, Switzerland
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40
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Abstract
Neurons have long held the spotlight as the central players of the nervous system, but we must remember that we have equal numbers of astrocytes and neurons in the brain. Are these cells only filling up the space and passively nurturing the neurons, or do they also contribute to information transfer and processing? After several years of intense research since the pioneer discovery of astrocytic calcium waves and glutamate release onto neurons in vitro, the neuronal-glial studies have answered many questions thanks to technological advances. However, the definitive in vivo role of astrocytes remains to be addressed. In addition, it is becoming clear that diverse populations of astrocytes coexist with different molecular identities and specialized functions adjusted to their microenvironment, but do they all belong to the umbrella family of astrocytes? One population of astrocytes takes on a new function by displaying both support cell and stem cell characteristics in the neurogenic niches. Here, we define characteristics that classify a cell as an astrocyte under physiological conditions. We will also discuss the well-established and emerging functions of astrocytes with an emphasis on their roles on neuronal activity and as neural stem cells in adult neurogenic zones.
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41
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Cecchelli R, Berezowski V, Lundquist S, Culot M, Renftel M, Dehouck MP, Fenart L. Modelling of the blood–brain barrier in drug discovery and development. Nat Rev Drug Discov 2007; 6:650-61. [PMID: 17667956 DOI: 10.1038/nrd2368] [Citation(s) in RCA: 435] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The market for neuropharmaceuticals is potentially one of the largest sectors of the global pharmaceutical market owing to the increase in average life expectancy and the fact that many neurological disorders have been largely refractory to pharmacotherapy. The brain is a delicate organ that can efficiently protect itself from harmful compounds and precisely regulate its microenvironment. Unfortunately, the same mechanisms can also prove to be formidable hurdles in drug development. An improved understanding of the regulatory interfaces that exist between blood and brain may provide novel and more effective strategies to treat neurological disorders.
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Affiliation(s)
- Romeo Cecchelli
- Laboratoire de physiopathologie de la barrière hémato-encéphalique E.A.2465, IMPRT IFR-114, Université d'Artois, Faculté Jean Perrin, 62307 Lens, France.
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42
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Smith M, Omidi Y, Gumbleton M. Primary porcine brain microvascular endothelial cells: biochemical and functional characterisation as a model for drug transport and targeting. J Drug Target 2007; 15:253-68. [PMID: 17487694 DOI: 10.1080/10611860701288539] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The blood-brain barrier (BBB) remains a significant obstacle to the delivery of therapeutic agents into the central nervous system (CNS). Primary cell cultures of brain capillary endothelial cells represent the closest possible phenotype to the in vivo BBB cell providing a convenient model for the study of transport systems and events that mediate solute delivery to the CNS. In this investigation we have characterized an in vitro primary BBB model from porcine brain microvascular endothelial capillary (PBMVEC) cells after recovery from cryopreservation of upto 12 months and studied their modulation by astrocytes. Co-cultures of PBMVECs with astrocytes (C6 astroglioma) resulted in trans-endothelial electrical resistance of up to approximately 900Omega cm2 and marked discrimination between the para- and trans- cellular markers sucrose and propranolol. Micrographs of confluent monolayers of PBMVECs showed the presence of tight junction complexes and vesicles with the morphological characteristics of either caveolae or clathrin coated pits. Extensive RT-PCR evaluation highlighted the expression of tight junction transcripts, ABC transporters, leptin receptor and select nutrient transporters. Functional studies examined the kinetics of transport of glucose, large neutral amino acids and p-glycoprotein (P-gp). Our findings indicate primary PBMVECs retain many barrier characteristics and transport pathways of the in vivo BBB. Further, primary cells can be stored as frozen stocks which can be thawed and cultured without phenotypic drift many months after isolation. Frozen PBMVECs therefore serve as a robust and convenient in vitro cell culture tool for research programs involving CNS drug delivery and targeting and in studies addressing blood-brain barrier transport mechanisms.
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Affiliation(s)
- Mathew Smith
- Pharmaceutical Cell Biology, Welsh School of Pharmacy, Cardiff University, Cardiff, UK
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43
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Siddharthan V, V. Kim Y, Liu S, Kim KS. Human astrocytes/astrocyte-conditioned medium and shear stress enhance the barrier properties of human brain microvascular endothelial cells. Brain Res 2007; 1147:39-50. [PMID: 17368578 PMCID: PMC2691862 DOI: 10.1016/j.brainres.2007.02.029] [Citation(s) in RCA: 145] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 01/12/2007] [Accepted: 02/02/2007] [Indexed: 11/20/2022]
Abstract
The blood-brain barrier (BBB) is a structural and functional barrier that regulates the passage of molecules into and out of the brain to maintain the neural microenvironment. We have previously developed the in vitro BBB model with human brain microvascular endothelial cells (HBMEC). However, in vivo HBMEC are shown to interact with astrocytes and also exposed to shear stress through blood flow. In an attempt to develop the BBB model to mimic the in vivo condition we constructed the flow-based in vitro BBB model using HBMEC and human fetal astrocytes (HFA). We also examined the effect of astrocyte-conditioned medium (ACM) in lieu of HFA to study the role of secreted factor(s) on the BBB properties. The tightness of HBMEC monolayer was assessed by the permeability of dextran and propidium iodide as well as by measuring the transendothelial electrical resistance (TEER). We showed that the HBMEC permeability was reduced and TEER was increased by non-contact, co-cultivation with HFA and ACM. The exposure of HBMEC to shear stress also exhibited decreased permeability. Moreover, HFA/ACM and shear flow exhibited additive effect of decreasing the permeability of HBMEC monolayer. In addition, we showed that the HBMEC expression of ZO-1 (tight junction protein) was increased by co-cultivation with ACM and in response to shear stress. These findings suggest that the non-contact co-cultivation with HFA helps maintain the barrier properties of HBMEC by secreting factor(s) into the medium. Our in vitro flow model system with the cells of human origin should be useful for studying the interactions between endothelial cells, glial cells, and secreted factor(s) as well as the role of shear stress in the barrier property of HBMEC.
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Affiliation(s)
- Venkatraman Siddharthan
- Division of Pediatric Infectious Diseases, Johns Hopkins University, School of Medicine, Baltimore, MD 21287
| | - Yuri V. Kim
- Division of Pediatric Infectious Diseases, Johns Hopkins University, School of Medicine, Baltimore, MD 21287
| | - Suyi Liu
- World Precision Instruments Inc., 175 Sarasota Center Blvd, Sarasota FL 34240 U.S.A
| | - Kwang Sik Kim
- Correspondence: Prof. Kwang Sik Kim, Division of Pediatric Infectious Diseases, Johns Hopkins University, School of Medicine, 600 North Wolfe Street, Park 256, Baltimore, MD 21287. , Phone: 410-614-3917, Fax: 410-614-1491
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44
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Pan W, Kastin AJ, Daniel J, Yu C, Baryshnikova LM, von Bartheld CS. TNFalpha trafficking in cerebral vascular endothelial cells. J Neuroimmunol 2007; 185:47-56. [PMID: 17316829 PMCID: PMC1924920 DOI: 10.1016/j.jneuroim.2007.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 01/03/2007] [Accepted: 01/16/2007] [Indexed: 11/23/2022]
Abstract
Using small tags, we tracked the pathway of tumor necrosis factor (TNF)alpha across cerebral vascular endothelial cells. In cerebral microvessel derived RBE4 cells, (125)I-TNFalpha had rapid endocytosis within the first 20 min and showed substantial exocytosis in the intact form. Biotinylated TNFalpha was detected at different time points after endocytosis by streptavidin-Quantum dots which showed its time-dependent colocalization with intracellular organelles. In mice, electron microscopic autoradiography after intravenous injection of (125)I-TNFalpha showed its transcytosis, as signals emerged on the abluminal side of the endothelial cells and reached brain parenchyma. The vesicular trafficking of TNFalpha reflects the immunomodulatory potential of peripheral cytokines for the CNS.
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Affiliation(s)
- Weihong Pan
- Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA.
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45
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Brown RC, Morris AP, O'Neil RG. Tight junction protein expression and barrier properties of immortalized mouse brain microvessel endothelial cells. Brain Res 2006; 1130:17-30. [PMID: 17169347 PMCID: PMC1995120 DOI: 10.1016/j.brainres.2006.10.083] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Revised: 10/19/2006] [Accepted: 10/22/2006] [Indexed: 11/27/2022]
Abstract
Understanding the molecular and biochemical mechanisms regulating the blood-brain barrier is aided by in vitro model systems. Many studies have used primary cultures of brain microvessel endothelial cells for this purpose. However, primary cultures limit the generation of material for molecular and biochemical assays since cells grow slowly, are prone to contamination by other neurovascular unit cells, and lose blood-brain barrier characteristics when passaged. To address these issues, immortalized cell lines have been generated. In these studies, we assessed the suitability of the immortalized mouse brain endothelial cell line, bEnd3, as a blood-brain barrier model. RT-PCR and immunofluorescence indicated expression of multiple tight junction proteins. bEnd3 cells formed barriers to radiolabeled sucrose, and responded like primary cultures to disrupting stimuli. Exposing cells to serum-free media on their basolateral side significantly decreased paracellular permeability; astrocyte-conditioned media did not enhance barrier properties. The serum-free media-induced decrease in permeability was correlated with an increase in claudin-5 and zonula occludens-1 immunofluorescence at cell-cell contracts. We conclude that bEnd3 cells are an attractive candidate as a model of the blood-brain barrier due to their rapid growth, maintenance of blood-brain barrier characteristics over repeated passages, formation of functional barriers and amenability to numerous molecular interventions.
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Affiliation(s)
- Rachel C Brown
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, 6431 Fannin, Houston, TX 77030, USA
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46
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Su Y, Sinko PJ. Drug delivery across the blood–brain barrier: why is it difficult? how to measure and improve it? Expert Opin Drug Deliv 2006; 3:419-35. [PMID: 16640501 DOI: 10.1517/17425247.3.3.419] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The development of drugs that act in the CNS has been significantly impeded by the difficulty of delivering them across the blood-brain barrier (BBB). This article aims to provide the reader with a critical overview of important issues in the discovery and development of drugs that need to enter the brain to elicit pharmacological activity, focusing particularly on i) the role of drug transporters in brain permeation and how to manipulate them to enhance drug brain bioavailability; ii) the successful application, limitations and challenges of commonly used in vitro and in vivo methodologies for measuring drug transport across the BBB, and iii) a discussion of recently developed strategies (e.g., modulation of efflux transporters by chemical inhibitors and the employment of delivery vectors taking advantage of native transport systems at the BBB) for facilitating drug penetration into the brain.
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Affiliation(s)
- Yaming Su
- Department of Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers, State University of New Jersey, 160 Frelinghuysen Road, Piscataway, NJ 08854, USA
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47
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Kusch-Poddar M, Drewe J, Fux I, Gutmann H. Evaluation of the immortalized human brain capillary endothelial cell line BB19 as a human cell culture model for the blood–brain barrier. Brain Res 2005; 1064:21-31. [PMID: 16289483 DOI: 10.1016/j.brainres.2005.10.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Revised: 10/05/2005] [Accepted: 10/11/2005] [Indexed: 11/23/2022]
Abstract
In vitro models of the blood-brain barrier (BBB) play a major role in the study of BBB permeability of drug candidates. However, most established in vitro models use cells of non-human origin, which is not optimal for the prediction of brain permeability in humans. The aim of this study was to assess the human brain capillary endothelial cell line BB19 for its usefulness as an in vitro model of the human BBB. Restrictive tight junctions are a prerequisite for drug transport studies. Sucrose permeability of BB19 cells on different filters was compared to porcine brain capillary endothelial cells (BCEC). Tightness of BB19 cell monolayers still needs further optimization. Hardly any discrimination between Sucrose and Propranolol (P(app) = 1.30 x 10(-5) vs. 2.18 x 10(-5) cm/s) was seen. Cells showed an improvement towards a more primary BCEC morphology with C6 conditioned medium, dexamethasone, and 1,25-dihydroxyvitamin D3. The presence of P-glycoprotein (P-gp), MRP4 and BCRP, ABC-transporters located in the BBB, has been shown on mRNA level, by immunostaining, and western blot. MRP1, MRP2, MRP5, OAT3, and OAT4 were also detected by RT-PCR. Functional properties of the BBB were shown with uptake of propranolol, morphine, and sucrose. Uptake studies with daunomycin and the P-gp inhibitor verapamil showed functional activity of P-gp. We conclude that BB19 cells might be feasible as a human in vitro model of the BBB for drug uptake studies. However, for the assessment of transport studies, further improvements of this model are necessary.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/drug effects
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP-Binding Cassette Transporters/drug effects
- ATP-Binding Cassette Transporters/metabolism
- Adrenergic beta-Antagonists/metabolism
- Animals
- Antibiotics, Antineoplastic/metabolism
- Biological Transport, Active/drug effects
- Biological Transport, Active/physiology
- Blood-Brain Barrier/drug effects
- Blood-Brain Barrier/metabolism
- Brain/blood supply
- Calcium Channel Blockers/metabolism
- Capillary Permeability/drug effects
- Capillary Permeability/physiology
- Cell Culture Techniques/methods
- Cell Line
- Cells, Cultured
- Daunorubicin/metabolism
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Humans
- Models, Biological
- Morphine/metabolism
- Narcotics/metabolism
- Propranolol/metabolism
- Sucrose/metabolism
- Swine
- Verapamil/metabolism
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Affiliation(s)
- Manisha Kusch-Poddar
- Department of Clinical Pharmacology and Toxicology, University Hospital Basel, Switzerland
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48
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Fitsanakis VA, Piccola G, Aschner JL, Aschner M. Manganese transport by rat brain endothelial (RBE4) cell-based transwell model in the presence of astrocyte conditioned media. J Neurosci Res 2005; 81:235-43. [PMID: 15948148 DOI: 10.1002/jnr.20560] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Manganese (Mn), an essential nutrient, is neurotoxic at high levels and has been associated with the development of a parkinsonian syndrome termed manganism. Currently, the mechanisms responsible for transporting Mn across the blood-brain barrier (BBB) are unknown. By using rat brain endothelial 4 (RBE4) cell monolayers cultured in astrocyte-conditioned media (ACM), we examine the effects of temperature, energy, proton (pH), iron (Fe), and sodium (Na(+)) dependence on Mn transport. Our results suggest that Mn transport is temperature, energy, and pH dependent, but not Fe or Na(+) dependent. These data suggest that Mn transport across the BBB is an active process, but they also demonstrate that the presence of ACM in endothelial cell cultures decreases the permeability of these cells to Mn, reinforcing the use of ACM or astrocyte cocultures in studies examining metal transport across the BBB.
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Affiliation(s)
- Vanessa A Fitsanakis
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232-2495, USA
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49
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Weksler BB, Subileau EA, Perrière N, Charneau P, Holloway K, Leveque M, Tricoire-Leignel H, Nicotra A, Bourdoulous S, Turowski P, Male DK, Roux F, Greenwood J, Romero IA, Couraud PO. Blood-brain barrier-specific properties of a human adult brain endothelial cell line. FASEB J 2005; 19:1872-4. [PMID: 16141364 DOI: 10.1096/fj.04-3458fje] [Citation(s) in RCA: 1010] [Impact Index Per Article: 53.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Establishment of a human model of the blood-brain barrier has proven to be a difficult goal. To accomplish this, normal human brain endothelial cells were transduced by lentiviral vectors incorporating human telomerase or SV40 T antigen. Among the many stable immortalized clones obtained by sequential limiting dilution cloning of the transduced cells, one was selected for expression of normal endothelial markers, including CD31, VE cadherin, and von Willebrand factor. This cell line, termed hCMEC/D3, showed a stable normal karyotype, maintained contact-inhibited monolayers in tissue culture, exhibited robust proliferation in response to endothelial growth factors, and formed capillary tubes in matrix but no colonies in soft agar. hCMEC/D3 cells expressed telomerase and grew indefinitely without phenotypic dedifferentiation. These cells expressed chemokine receptors, up-regulated adhesion molecules in response to inflammatory cytokines, and demonstrated blood-brain barrier characteristics, including tight junctional proteins and the capacity to actively exclude drugs. hCMEC/D3 are excellent candidates for studies of blood-brain barrier function, the responses of brain endothelium to inflammatory and infectious stimuli, and the interaction of brain endothelium with lymphocytes or tumor cells. Thus, hCMEC/D3 represents the first stable, fully characterized, well-differentiated human brain endothelial cell line and should serve as a widely usable research tool.
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MESH Headings
- Agar/chemistry
- Animals
- Antigens, CD
- Antigens, Polyomavirus Transforming/biosynthesis
- Antigens, Polyomavirus Transforming/genetics
- Blood-Brain Barrier/drug effects
- Blotting, Western
- Brain/cytology
- Brain/drug effects
- Brain/metabolism
- Brain/pathology
- Cadherins/biosynthesis
- Capillaries/pathology
- Cattle
- Cell Adhesion
- Cell Culture Techniques/methods
- Cell Line
- Cell Proliferation
- Cells, Cultured
- Cloning, Molecular
- Collagen/pharmacology
- Cytokines/metabolism
- Drug Combinations
- Drug Resistance, Multiple
- Endothelial Cells/cytology
- Endothelial Cells/pathology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/pathology
- Female
- Flow Cytometry
- Humans
- Immunohistochemistry
- Karyotyping
- Laminin/pharmacology
- Lentivirus/genetics
- Lymphocytes/metabolism
- Microscopy, Fluorescence
- Models, Biological
- Perfusion
- Permeability
- Phenotype
- Platelet Endothelial Cell Adhesion Molecule-1/biosynthesis
- Proteoglycans/pharmacology
- RNA/metabolism
- Rats
- Reverse Transcriptase Polymerase Chain Reaction
- Signal Transduction
- Telomerase/genetics
- Telomerase/metabolism
- Time Factors
- Up-Regulation
- von Willebrand Factor/biosynthesis
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Affiliation(s)
- B B Weksler
- Institut Cochin, CNRS UMR 8104-INSERM U567, Université René Descartes, Paris, France.
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Roux F, Couraud PO. Rat brain endothelial cell lines for the study of blood-brain barrier permeability and transport functions. Cell Mol Neurobiol 2005; 25:41-58. [PMID: 15962508 DOI: 10.1007/s10571-004-1376-9] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
(1) In vitro models of the BBB have been developed from cocultures between bovine, porcine, rodent or human brain capillary endothelial cells with rodent or human astrocytes. Since most in vivo BBB studies have been performed with small laboratory animals, especially rats, it is important to establish a rat brain endothelial (RBE) cell culture system that will allow correlations between in vitro and in vivo results. The present review will constitute a brief description of the best characterized RBE cell lines (RBE4, GP8/3.9, GPNT, RBEC1, TR-BBBs and rBCEC4 cell lines) and will summarize their recent and important contribution to our current knowledge of the BBB transport functions and permeability to blood-borne solutes, drugs, and cells. (2) In most cases, primary cultures of RBE cells were transduced with an immortalizing gene (SV40 or polyoma virus large T-antigen or adenovirus E1A), either by transfection of plasmid DNA or by infection using retroviral vectors. In one case however, the conditionally immortalized TR-BBB cell line was derived from primary cultures of brain endothelial cells of SV40-T-expressing transgenic rats. (3) All cell lines appear to have an endothelial morphology. The absence of foci formation would mean that the cells are not transformed. The endothelial origin is shown by the expression of Factor VIII-related antigen. Immortalized RBE cells express all the enzymes and transporters that are considered as specific for the blood-brain barrier endothelium, with similar characteristics to those expected from in vivo analyses, but at a significantly lower level. Some RBE cell lines are responsive to astroglial factors, such as RBE4 cells, rBEC4, and TR-BBB cells. None of the immortalized RBE cell lines appear to generate the necessary restrictive paracellular barrier properties that would allow to use them in transendothelial permeability screening. (4) RBE cell lines have been used to demonstrate that transporters such as organic cation transporter/carnitine transporter, serotonin transporter, and the ATA2 system A isoform are expressed in rat brain endothelium. When the transporter is shown to be expressed with the same properties in the immortalized RBE cells as in vivo, regulation studies may be initiated even if the transporter is down-regulated. Pharmacological applications have been proposed with well-characterized transporters such as monocarboxylic acid transporter-1, large neutral amino acid tansporter-1, nucleoside carrier systems, and P-glycoprotein. RBE cell monolayers have also been used to investigate the mechanism of the transendothelial transport of large molecules, such as immunoliposomes or nanoparticles, potentially useful as drug delivery vectors to the brain. (5) RBE4 and GP8 cell lines have been extensively used to demonstrate that intercellular adhesion molecule-1 (ICAM-1) engagement in brain endothelial cells triggers multiple signal transduction pathways. Using functional assays, it was established that ICAM-1 signaling is intimately and actively involved in facilitating lymphocyte infiltration. (6) Several RBE cell lines have been described, which constitute tentative in vitro models of the rat BBB. The major limitation of these models generally appears to be due to their relatively high paracellular permeability to small molecules, thus limiting their use for permeability studies. The strategies developed for the production of these RBE cell lines will enable the characterization of still more efficient permeability models, as well as the immortalization of human brain endothelial cells.
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