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Martinez-Lozada Z, Todd FW, Schober AL, Krizman E, Robinson MB, Murai KK. Cooperative and competitive regulation of the astrocytic transcriptome by neurons and endothelial cells: Impact on astrocyte maturation. J Neurochem 2023; 167:52-75. [PMID: 37525469 PMCID: PMC10543513 DOI: 10.1111/jnc.15908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 06/19/2023] [Accepted: 06/20/2023] [Indexed: 08/02/2023]
Abstract
Astrocytes have essential roles in central nervous system (CNS) health and disease. During development, immature astrocytes show complex interactions with neurons, endothelial cells, and other glial cell types. Our work and that of others have shown that these interactions are important for astrocytic maturation. However, whether and how these cells work together to control this process remains poorly understood. Here, we test the hypothesis that cooperative interactions of astrocytes with neurons and endothelial cells promote astrocytic maturation. Astrocytes were cultured alone, with neurons, endothelial cells, or a combination of both. This was followed by astrocyte sorting, RNA sequencing, and bioinformatic analysis to detect transcriptional changes. Across culture configurations, 7302 genes were differentially expressed by 4 or more fold and organized into 8 groups that demonstrate cooperative and antagonist effects of neurons and endothelia on astrocytes. We also discovered that neurons and endothelial cells caused splicing of 200 and 781 mRNAs, respectively. Changes in gene expression were validated using quantitative PCR, western blot (WB), and immunofluorescence analysis. We found that the transcriptomic data from the three-culture configurations correlated with protein expression of three representative targets (FAM107A, GAT3, and GLT1) in vivo. Alternative splicing results also correlated with cortical tissue isoform representation of a target (Fibronectin 1) at different developmental stages. By comparing our results to published transcriptomes of immature and mature astrocytes, we found that neurons or endothelia shift the astrocytic transcriptome toward a mature state and that the presence of both cell types has a greater effect on maturation than either cell alone. These results increase our understanding of cellular interactions/pathways that contribute to astrocytic maturation. They also provide insight into how alterations to neurons and/or endothelial cells may alter astrocytes with implications for astrocytic changes in CNS disorders and diseases.
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Affiliation(s)
- Zila Martinez-Lozada
- Departments of Pediatrics and Systems Pharmacology & Translational Therapeutics, The Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA, 19104-4318
| | - Farmer W. Todd
- Centre for Research in Neuroscience, Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada H3G 1A4
| | - Alexandra L. Schober
- Centre for Research in Neuroscience, Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada H3G 1A4
| | - Elizabeth Krizman
- Departments of Pediatrics and Systems Pharmacology & Translational Therapeutics, The Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA, 19104-4318
| | - Michael B. Robinson
- Departments of Pediatrics and Systems Pharmacology & Translational Therapeutics, The Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA, 19104-4318
| | - Keith K. Murai
- Centre for Research in Neuroscience, Department of Neurology & Neurosurgery, Brain Repair and Integrative Neuroscience Program, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada H3G 1A4
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Extracellular vesicles derived from bone marrow mesenchymal stem cells alleviate neurological deficit and endothelial cell dysfunction after subarachnoid hemorrhage via the KLF3-AS1/miR-83-5p/TCF7L2 axis. Exp Neurol 2022; 356:114151. [PMID: 35738418 DOI: 10.1016/j.expneurol.2022.114151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 06/14/2022] [Accepted: 06/16/2022] [Indexed: 11/21/2022]
Abstract
BACKGROUND New data are accumulating on the effects of mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) in cerebrovascular diseases. We explored the potential role of KLF3-AS1-containing bone marrow MSC-EVs (BMSC-EVs) in a rat model of subarachnoid hemorrhage (SAH). METHODS A rat model of SAH was established by endovascular perforation method, into which KLF3-AS1-containing EVs from BMSCs or miR-183-5p mimic were injected. Further, brain microvascular endothelial cells (BMECs) were induced by oxyhemoglobin (OxyHb) to simulate in vitro setting, which were co-cultured with KLF3-AS1-containing EVs from BMSCs. Effects of KLF3-AS1 on neurological deficits in vivo and endothelial cell dysfunction in vitro were investigated. We also performed bioinformatics analysis to predict downstream factors miR-183-5p and TCF7L2, which were verified by RIP, RNA pull-down and luciferase activity assays. RESULTS BMSC-EVs was demonstrated to alleviate neurological deficits in SAH rats and endothelial cell dysfunction in OxyHb-induced BMECs. In addition, BMSC-EVs were shown to deliver KLF3-AS1 to BMECs, where KLF3-AS1 bound to miR-183-5p and miR-183-5p targeted TCF7L2. In vivo results confirmed that BMSC-EVs regulated the KLF3-AS1/miR-183-5p/TCF7L2 signaling axis to attenuate neurological deficit and endothelial dysfunction after SAH. CONCLUSION Overall, KLF3-AS1 delivered by BMSC-EVs upregulate TCF7L2 expression by binding to miR-138-5p, thus attenuating neurological deficits and endothelial dysfunction after SAH.
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Abstract
In vitro blood-brain barrier (BBB) models have been widely used to simulate in vivo models due to their low cost, feasibility, and repeatability. To serve as a valid substitute, the in vitro BBB should have the similar barrier function as that in vivo. This chapter summarizes the detailed methods for quantifying the barrier function, e.g., the permeability of the BBB to water, ions, and solutes for an in vitro BBB generated on the Transwell filter.
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Martinez-Lozada Z, Robinson MB. Reciprocal communication between astrocytes and endothelial cells is required for astrocytic glutamate transporter 1 (GLT-1) expression. Neurochem Int 2020; 139:104787. [PMID: 32650029 DOI: 10.1016/j.neuint.2020.104787] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/15/2020] [Accepted: 06/14/2020] [Indexed: 12/12/2022]
Abstract
Astrocytes have diverse functions that are supported by their anatomic localization between neurons and blood vessels. One of these functions is the clearance of extracellular glutamate. Astrocytes clear glutamate using two Na+-dependent glutamate transporters, GLT-1 (also called EAAT2) and GLAST (also called EAAT1). GLT-1 expression increases during synaptogenesis and is a marker of astrocyte maturation. Over 20 years ago, several groups demonstrated that astrocytes in culture express little or no GLT-1 and that neurons induce expression. We recently demonstrated that co-culturing endothelia with mouse astrocytes also induced expression of GLT-1 and GLAST. These increases were blocked by an inhibitor of γ-secretase. This and other observations are consistent with the hypothesis that Notch signaling is required, but the ligands involved were not identified. In the present study, we used rat astrocyte cultures to further define the mechanisms by which endothelia induce expression of GLT-1 and GLAST. We found that co-cultures of astrocytes and endothelia express higher levels of GLT-1 and GLAST protein and mRNA. That endothelia activate Hes5, a transcription factor target of Notch, in astrocytes. Using recombinant Notch ligands, anti-Notch ligand neutralizing antibodies, and shRNAs, we provide evidence that both Dll1 and Dll4 contribute to endothelia-dependent regulation of GLT-1. We also provide evidence that astrocytes secrete a factor(s) that induces expression of Dll4 in endothelia and that this effect is required for Notch-dependent induction of GLT-1. Together these studies indicate that reciprocal communication between astrocytes and endothelia is required for appropriate astrocyte maturation and that endothelia likely deploy additional non-Notch signals to induce GLT-1.
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Affiliation(s)
- Zila Martinez-Lozada
- Departments of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA, 19104-4318
| | - Michael B Robinson
- Departments of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA, 19104-4318; Systems Pharmacology and Translational Therapeutics, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, 19104-4318, USA.
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5
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Barui AK, Jhelum P, Nethi SK, Das T, Bhattacharya D, B V, Karri S, Chakravarty S, Patra CR. Potential Therapeutic Application of Zinc Oxide Nanoflowers in the Cerebral Ischemia Rat Model through Neuritogenic and Neuroprotective Properties. Bioconjug Chem 2020; 31:895-906. [PMID: 32050064 DOI: 10.1021/acs.bioconjchem.0c00030] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Neuritogenesis, a complex process of the sprouting of neurites, plays a vital role in the structural and functional restoration of cerebral ischemia-injured neuronal tissue. Practically, there is no effective long-term treatment strategy for cerebral ischemia in clinical practice to date due to several limitations of conventional therapies, facilitating the urgency to develop new alternative therapeutic approaches. Herein, for the first time we report that pro-angiogenic nanomaterials, zinc oxide nanoflowers (ZONF), exhibit neuritogenic activity by elevating mRNA expression of different neurotrophins, following PI3K/Akt-MAPK/ERK signaling pathways. Further, ZONF administration to global cerebral ischemia-induced Fischer rats shows improved neurobehavior and enhanced synaptic plasticity of neurons via upregulation of Neurabin-2 and NT-3, revealing their neuroprotective activity. Altogether, this study offers the basis for exploitation of angio-neural cross talk of other pro-angiogenic nano/biomaterials for future advancement of alternative treatment strategies for cerebral ischemia, where neuritogenesis and neural repair are highly critical.
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Affiliation(s)
- Ayan Kumar Barui
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| | - Priya Jhelum
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India
| | - Susheel Kumar Nethi
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| | - Tapatee Das
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| | - Dwaipayan Bhattacharya
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India
| | - Vinothkumar B
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India
| | - Shailaja Karri
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India
| | - Sumana Chakravarty
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
| | - Chitta Ranjan Patra
- Department of Applied Biology, CSIR-Indian Institute of Chemical Technology, Uppal Road, Tarnaka, Hyderabad 500007, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, Uttar Pradesh 201002, India
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6
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Fu BM. Transport Across the Blood-Brain Barrier. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1097:235-259. [PMID: 30315549 DOI: 10.1007/978-3-319-96445-4_13] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The blood-brain barrier (BBB) is a dynamic barrier essential for maintaining the microenvironment of the brain. Although the special anatomical features of the BBB determine its protective role for the central nervous system (CNS) from blood-borne neurotoxins, however, the BBB extremely limits the therapeutic efficacy of drugs into the CNS, which greatly hinders the treatment of major brain diseases. This chapter summarized the unique structures of the BBB; described a variety of in vivo and in vitro experimental methods for determining the transport properties of the BBB and the permeability of the BBB to water, ions, and solutes including nutrients, therapeutic agents, and drug carriers; and presented recently developed mathematical models which quantitatively correlate the anatomical structures of the BBB with its barrier functions. Recent findings for modulation of the BBB permeability by chemical and physical stimuli were described. Finally, drug delivery strategies through specific trans-BBB routes were discussed.
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Affiliation(s)
- Bingmei M Fu
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY, USA.
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7
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Reuten R, Patel TR, McDougall M, Rama N, Nikodemus D, Gibert B, Delcros JG, Prein C, Meier M, Metzger S, Zhou Z, Kaltenberg J, McKee KK, Bald T, Tüting T, Zigrino P, Djonov V, Bloch W, Clausen-Schaumann H, Poschl E, Yurchenco PD, Ehrbar M, Mehlen P, Stetefeld J, Koch M. Structural decoding of netrin-4 reveals a regulatory function towards mature basement membranes. Nat Commun 2016; 7:13515. [PMID: 27901020 PMCID: PMC5141367 DOI: 10.1038/ncomms13515] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 10/09/2016] [Indexed: 02/07/2023] Open
Abstract
Netrins, a family of laminin-related molecules, have been proposed to act as guidance cues either during nervous system development or the establishment of the vascular system. This was clearly demonstrated for netrin-1 via its interaction with the receptors DCC and UNC5s. However, mainly based on shared homologies with netrin-1, netrin-4 was also proposed to play a role in neuronal outgrowth and developmental/pathological angiogenesis via interactions with netrin-1 receptors. Here, we present the high-resolution structure of netrin-4, which shows unique features in comparison with netrin-1, and show that it does not bind directly to any of the known netrin-1 receptors. We show that netrin-4 disrupts laminin networks and basement membranes (BMs) through high-affinity binding to the laminin γ1 chain. We hypothesize that this laminin-related function is essential for the previously described effects on axon growth promotion and angiogenesis. Our study unveils netrin-4 as a non-enzymatic extracellular matrix protein actively disrupting pre-existing BMs. Netrins are secreted guidance factors that promote axon outgrowth and orientation during nervous system development. Here the authors present structural and biological evidence that netrin-4 is not a guidance cue per se, but rather functions to modulate laminin-laminin interactions.
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Affiliation(s)
- Raphael Reuten
- Institute for Dental Research and Oral Musculoskeletal Biology, Medical Faculty, University of Cologne, Joseph-Stelzmann-Strasse 52, Cologne 50931, Germany.,Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Joseph-Stelzmann-Strasse 52, Cologne 50931, Germany
| | - Trushar R Patel
- Alberta RNA Research and Training Institute, Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta T1K 3M4, Canada.,School of Biosciences, University of Birmingham, Edgbaston B15 2TT, UK
| | - Matthew McDougall
- Department of Chemistry, University of Manitoba, Winnipeg R3T 2N2, Canada
| | - Nicolas Rama
- Apoptosis, Cancer and Development Laboratory, Equipe labellisée 'La Ligue', LabEx DEVweCAN, Centre de Recherche en Cancérologie de Lyon, INSERM U1052-CNRS UMR5286, Université de Lyon, Centre Léon Bérard, Lyon 69008, France
| | - Denise Nikodemus
- Institute for Dental Research and Oral Musculoskeletal Biology, Medical Faculty, University of Cologne, Joseph-Stelzmann-Strasse 52, Cologne 50931, Germany.,Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Joseph-Stelzmann-Strasse 52, Cologne 50931, Germany
| | - Benjamin Gibert
- Apoptosis, Cancer and Development Laboratory, Equipe labellisée 'La Ligue', LabEx DEVweCAN, Centre de Recherche en Cancérologie de Lyon, INSERM U1052-CNRS UMR5286, Université de Lyon, Centre Léon Bérard, Lyon 69008, France
| | - Jean-Guy Delcros
- Apoptosis, Cancer and Development Laboratory, Equipe labellisée 'La Ligue', LabEx DEVweCAN, Centre de Recherche en Cancérologie de Lyon, INSERM U1052-CNRS UMR5286, Université de Lyon, Centre Léon Bérard, Lyon 69008, France
| | - Carina Prein
- Center for Applied Tissue Engineering and Regenerative Medicine-CANTER, Munich University of Applied Sciences, Lothstrasse 34, Munich D-80335, Germany.,Laboratory of Experimental Surgery and Regenerative Medicine - ExperiMed, Department of Surgery, Clinical Center University of Munich, Nussbaumstrasse 20, Munich D-80336, Germany.,Center for Nanoscience-CeNS, Geschwister-Scholl-Platz 1, Munich D-80539, Germany
| | - Markus Meier
- Department of Chemistry, University of Manitoba, Winnipeg R3T 2N2, Canada
| | - Stéphanie Metzger
- Laboratory for Cell and Tissue Engineering, Department of Obstetrics, University Hospital Zurich, Schmelzbergstr. 12, Zurich 8091, Switzerland
| | - Zhigang Zhou
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.,Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Jennifer Kaltenberg
- Institute for Dental Research and Oral Musculoskeletal Biology, Medical Faculty, University of Cologne, Joseph-Stelzmann-Strasse 52, Cologne 50931, Germany.,Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Joseph-Stelzmann-Strasse 52, Cologne 50931, Germany
| | - Karen K McKee
- Department of Pathology, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
| | - Tobias Bald
- Department of Dermatology, University Hospital Magdeburg, Magdeburg 39120, Germany.,Laboratory of Experimental Dermatology, Department of Dermatology and Allergy, University of Bonn, Bonn 53105, Germany
| | - Thomas Tüting
- Department of Dermatology, University Hospital Magdeburg, Magdeburg 39120, Germany.,Laboratory of Experimental Dermatology, Department of Dermatology and Allergy, University of Bonn, Bonn 53105, Germany
| | - Paola Zigrino
- Department of Dermatology and Venerology, University of Cologne, Cologne 50931, Germany
| | - Valentin Djonov
- Institute of Anatomy, University of Bern, Baltzerstrasse 2, Bern 3000, Switzerland
| | - Wilhelm Bloch
- Institute of Cardiovascular Research and Sport Medicine, Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, Cologne 50933, Germany
| | - Hauke Clausen-Schaumann
- Center for Applied Tissue Engineering and Regenerative Medicine-CANTER, Munich University of Applied Sciences, Lothstrasse 34, Munich D-80335, Germany.,Center for Nanoscience-CeNS, Geschwister-Scholl-Platz 1, Munich D-80539, Germany
| | - Ernst Poschl
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Peter D Yurchenco
- Department of Pathology, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
| | - Martin Ehrbar
- Laboratory for Cell and Tissue Engineering, Department of Obstetrics, University Hospital Zurich, Schmelzbergstr. 12, Zurich 8091, Switzerland
| | - Patrick Mehlen
- Apoptosis, Cancer and Development Laboratory, Equipe labellisée 'La Ligue', LabEx DEVweCAN, Centre de Recherche en Cancérologie de Lyon, INSERM U1052-CNRS UMR5286, Université de Lyon, Centre Léon Bérard, Lyon 69008, France
| | - Jörg Stetefeld
- Department of Chemistry, University of Manitoba, Winnipeg R3T 2N2, Canada
| | - Manuel Koch
- Institute for Dental Research and Oral Musculoskeletal Biology, Medical Faculty, University of Cologne, Joseph-Stelzmann-Strasse 52, Cologne 50931, Germany.,Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Joseph-Stelzmann-Strasse 52, Cologne 50931, Germany
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8
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Chen Y, Huang XJ, Yu N, Xie Y, Zhang K, Wen F, Liu H, Di Q. HMGB1 Contributes to the Expression of P-Glycoprotein in Mouse Epileptic Brain through Toll-Like Receptor 4 and Receptor for Advanced Glycation End Products. PLoS One 2015; 10:e0140918. [PMID: 26485677 PMCID: PMC4613137 DOI: 10.1371/journal.pone.0140918] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 10/01/2015] [Indexed: 12/22/2022] Open
Abstract
The objective of the present study was to investigate the role of high-mobility group box-1 (HMGB1) in the seizure-induced P-glycoprotein (P-gp) overexpression and the underlying mechanism. Kainic acid (KA)-induced mouse seizure model was used for in vivo experiments. Male C57BL/6 mice were divided into four groups: normal saline control (NS) group, KA-induced epileptic seizure (EP) group, and EP group pretreated with HMGB1 (EP+HMGB1 group) or BoxA (HMGB1 antagonist, EP+BoxA group). Compared to the NS group, increased levels of HMGB1 and P-gp in the brain were observed in the EP group. Injection of HMGB1 before the induction of KA further increased the expression of P-gp while pre-treatment with BoxA abolished this up-regulation. Next, the regulatory role of HMGB1 and its potential involved signal pathways were investigated in mouse microvascular endothelial bEnd.3 cells in vitro. Cells were treated with HMGB1, HMGB1 plus lipopolysaccharide from Rhodobacter sphaeroides (LPS-RS) [toll-like receptor 4 (TLR4) antagonist], HMGB1 plus FPS-ZM1 [receptor for advanced glycation end products (RAGE) inhibitor], HMGB1 plus SN50 [nuclear factor-kappa B (NF-κB) inhibitor], or vehicle. Treatment with HMGB1 increased the expression levels of P-gp, TLR4, RAGE and the activation of NF-κB in bEnd.3 cells. These effects were inhibited by the pre-treatment with either LPS-RS or FPS-ZM1, and were abolished by the pre-treatment of SN50 or a combination treatment of both LPS-RS and FPS-ZM1. Luciferase reporter assays showed that exogenous expression of NF-κB p65 increased the promoter activity of multidrug resistance 1a (P-gp-encoding gene) in endothelial cells. These data indicate that HMGB1 contributes to the overexpression of P-gp in mouse epileptic brain tissues via activation of TLR4/RAGE receptors and the downstream transcription factor NF-κB in brain microvascular endothelial cells.
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Affiliation(s)
- Yan Chen
- Department of Neurology, Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing, Jiangsu, China
| | - Xian-Jing Huang
- Department of Neurology, Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing, Jiangsu, China
| | - Nian Yu
- Department of Neurology, Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yuan Xie
- Department of Neurology, Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing, Jiangsu, China
| | - Kang Zhang
- Department of Neurology, Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing, Jiangsu, China
| | - Fang Wen
- Department of Neurology, Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing, Jiangsu, China
| | - Hao Liu
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Qing Di
- Department of Neurology, Nanjing Brain Hospital affiliated to Nanjing Medical University, Nanjing, Jiangsu, China
- * E-mail:
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9
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Lien CF, Mohanta SK, Frontczak-Baniewicz M, Swinny JD, Zablocka B, Górecki DC. Absence of glial α-dystrobrevin causes abnormalities of the blood-brain barrier and progressive brain edema. J Biol Chem 2012; 287:41374-85. [PMID: 23043099 DOI: 10.1074/jbc.m112.400044] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The blood-brain barrier (BBB) plays a key role in maintaining brain functionality. Although mammalian BBB is formed by endothelial cells, its function requires interactions between endotheliocytes and glia. To understand the molecular mechanisms involved in these interactions is currently a major challenge. We show here that α-dystrobrevin (α-DB), a protein contributing to dystrophin-associated protein scaffolds in astrocytic endfeet, is essential for the formation and functioning of BBB. The absence of α-DB in null brains resulted in abnormal brain capillary permeability, progressively escalating brain edema, and damage of the neurovascular unit. Analyses in situ and in two-dimensional and three-dimensional in vitro models of BBB containing α-DB-null astrocytes demonstrated these abnormalities to be associated with loss of aquaporin-4 water and Kir4.1 potassium channels from glial endfeet, formation of intracellular vacuoles in α-DB-null astrocytes, and defects of the astrocyte-endothelial interactions. These caused deregulation of tight junction proteins in the endothelia. Importantly, α-DB but not dystrophins showed continuous expression throughout development in BBB models. Thus, α-DB emerges as a central organizer of dystrophin-associated protein in glial endfeet and a rare example of a glial protein with a role in maintaining BBB function. Its abnormalities might therefore lead to BBB dysfunction.
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Affiliation(s)
- Chun Fu Lien
- Molecular Medicine, School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth PO1 2DT, United Kingdom
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10
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Li G, Simon MJ, Cancel LM, Shi ZD, Ji X, Tarbell JM, Morrison B, Fu BM. Permeability of endothelial and astrocyte cocultures: in vitro blood-brain barrier models for drug delivery studies. Ann Biomed Eng 2010; 38:2499-511. [PMID: 20361260 DOI: 10.1007/s10439-010-0023-5] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2009] [Accepted: 03/19/2010] [Indexed: 11/28/2022]
Abstract
The blood-brain barrier (BBB) is a major obstacle for drug delivery to the brain. To seek for in vitro BBB models that are more accessible than animals for investigating drug transport across the BBB, we compared four in vitro cultured cell models: endothelial monoculture (bEnd3 cell line), coculture of bEnd3 and primary rat astrocytes (coculture), coculture with collagen type I and IV mixture, and coculture with Matrigel. The expression of the BBB tight junction proteins in these in vitro models was assessed using RT-PCR and immunofluorescence. We also quantified the hydraulic conductivity (L (p)), transendothelial electrical resistance (TER) and diffusive solute permeability (P) of these models to three solutes: TAMRA, Dextran 10K and Dextran 70K. Our results show that L (p) and P of the endothelial monoculture and coculture models are not different from each other. Compared with in vivo permeability data from rat pial microvessels, P of the endothelial monoculture and coculture models are not significantly different from in vivo data for Dextran 70K, but they are 2-4 times higher for TAMRA and Dextran 10K. This suggests that the endothelial monoculture and all of the coculture models are fairly good models for studying the transport of relatively large solutes across the BBB.
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Affiliation(s)
- Guanglei Li
- Department of Biomedical Engineering, The City College of the City University of New York, New York, NY 10031, USA
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13
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Crivellato E, Nico B, Ribatti D. Contribution of endothelial cells to organogenesis: a modern reappraisal of an old Aristotelian concept. J Anat 2007; 211:415-27. [PMID: 17683480 PMCID: PMC2375830 DOI: 10.1111/j.1469-7580.2007.00790.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/27/2007] [Indexed: 01/02/2023] Open
Abstract
It is well established that many tissue-derived factors are involved in blood vessel formation, but evidence is now emerging that endothelial cells themselves represent a crucial source of instructive signals to non-vascular tissue cells during organ development. Thus, endothelial cell signalling is currently believed to promote fundamental cues for cell fate specification, embryo patterning, organ differentiation and postnatal tissue remodelling. This review article summarizes some of the recent advances in our understanding of the role of endothelial cells as effector cells in organ formation.
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Affiliation(s)
- E Crivellato
- Department of Medical and Morphological Research, Anatomy Section, University of Udine, Italy.
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Lin G, Bjornsson CS, Smith KL, Abdul-Karim MA, Turner JN, Shain W, Roysam B. Automated image analysis methods for 3-D quantification of the neurovascular unit from multichannel confocal microscope images. Cytometry A 2006; 66:9-23. [PMID: 15934061 DOI: 10.1002/cyto.a.20149] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND There is a need for integrative and quantitative methods to investigate the structural and functional relations among elements of complex systems, such as the neurovascular unit (NVU), that involve multiple cell types, microvasculatures, and various genomic/proteomic/ionic functional entities. METHODS Vascular casting and selective labeling enabled simultaneous three-dimensional imaging of the microvasculature, cell nuclei, and cytoplasmic stains. Multidimensional segmentation was achieved by (i) bleed-through removal and attenuation correction; (ii) independent segmentation and morphometry for each corrected channel; and (iii) spatially associative feature computation across channels. The combined measurements enabled cell classification based on nuclear morphometry, cytoplasmic signals, and distance from vascular elements. Specific spatial relations among the NVU elements could be quantified. RESULTS A software system combining nuclear and vessel segmentation codes and associative features was constructed and validated. Biological variability contributed to misidentified nuclei (9.3%), undersegmentation of nuclei (3.7%), hypersegmentation of nuclei (14%), and missed nuclei (4.7%). Microvessel segmentation errors occurred rarely, mainly due to nonuniform lumen staining. CONCLUSIONS Associative features across fluorescence channels, in combination with standard features, enable integrative structural and functional analysis of the NVU. By labeling additional structural and functional entities, this method can be scaled up to larger-scale systems biology studies that integrate spatial and molecular information.
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Affiliation(s)
- Gang Lin
- Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180-3590, New York, USA
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15
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Abstract
The cerebrovascular endothelium exerts a profound influence on cerebral vessels and cerebral blood flow. This review summarizes current knowledge of various dilator and constrictor mechanisms intrinsic to the cerebrovascular endothelium. The endothelium contributes to the resting tone of cerebral arteries and arterioles by tonically releasing nitric oxide (NO•). Dilations can occur by stimulated release of NO•, endothelium-derived hyperpolarization factor, or prostanoids. During pathological conditions, the dilator influence of the endothelium can turn to that of constriction by a variety of mechanisms, including decreased NO• bioavailability and release of endothelin-1. The endothelium may participate in neurovascular coupling by conducting local dilations to upstream arteries. Further study of the cerebrovascular endothelium is critical for understanding the pathogenesis of a number of pathological conditions, including stroke, traumatic brain injury, and subarachnoid hemorrhage.
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Affiliation(s)
- Jon Andresen
- Department of Anesthesiology, Baylor College of Medicine, One Baylor Plaza, Suite 434D, Houston, Texas 77030, USA.
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16
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Abstract
Adaptation is a central organizing principle throughout biology, whether we are studying species, populations, or individuals. Adaptation in biological systems occurs in response to molar and molecular environments. Thus, we would predict that genetic systems and nervous systems would be dynamic (cybernetic) in contrast to previous conceptualizations with genes and brains fixed in form and function. Questions of nature versus nurture are meaningless, and we must turn to epigenetics--the way in which biology and experience work together to enhance adaptation throughout thick and thin. Defining endophenotypes--road markers that bring us closer to the biological origins of the developmental journey--facilitates our understanding of adaptive or maladaptive processes. For human behavioral disorders such as schizophrenia and autism, the inherent plasticity of the nervous system requires a systems approach to incorporate all of the myriad epigenetic factors that can influence such outcomes.
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Affiliation(s)
- Irving I Gottesman
- Department of Psychiatry and Department of Psychology, University of Minnesota, Minneapolis, MN 55454, USA.
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17
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Harmon D, Ghori K, Lan W, Shorten G. Effect of aprotinin on in vitro cerebral endothelial ICAM-1 expression induced by astrocyte-conditioned medium. Eur J Anaesthesiol 2005; 22:277-82. [PMID: 15892405 DOI: 10.1017/s0265021505000463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND OBJECTIVE Aprotinin administration may decrease the incidence of stroke associated with coronary artery bypass surgery by an unknown mechanism. Astrocytes exposed to hypoxia produce proinflammatory cytokines and upregulate intercellular adhesion molecule (ICAM)-1 on cerebral endothelium. This study investigated the effects of aprotinin on cerebral endothelial activation by hypoxic astrocytes in vitro. METHODS Mouse astrocytes were exposed to hypoxia in an anaerobic chamber for 4 h followed by reoxygenation for 24 h. Astrocyte-conditioned medium (ACM) collected from mouse astrocytes subjected to hypoxia/reoxygenation (HR) or normoxia were applied to mouse cerebral endothelial cell (MCEC) cultures for 4 and 24 h in normoxia. Endothelial cells were preincubated for 1 h with aprotinin (1600 KIU mL(-1)) prior to exposure to ACM. Flow cytometry was used to estimate endothelial ICAM-1 expression. Interleukin (IL)-1beta space concentrations in ACM were estimated with enzyme-linked immunosorbent assay (ELISA). Repeated comparisons were made using analysis of variance (ANOVA) and post hoc Tukey test as appropriate. P < 0.05 was considered significant. Data is presented as mean (standard deviation, SD). RESULTS MCEC ICAM-1 expression was greater after 24 h exposure to HR-ACM compared to normoxic-ACM (mean channel flouresence (MCF) 107.5 (4.5) vs. 74.3 (4.5), respectively, P < 0.001). ICAM-1 expression was decreased by aprotinin preincubation compared to control (MCF 91.0 (1.1) vs. 107.5 (2.1), P = 0.006). Supernatant IL-1beta concentrations in astrocytes exposed to HR were greater than those exposed to normoxia (7.1 (0.2) vs. 4.1 (0.2), P = 0.01). CONCLUSIONS This may be a neuroprotective mechanism associated with aprotinin administration.
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Affiliation(s)
- D Harmon
- Walton Centre for Neurology and Neurosurgery, Liverpool, UK.
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18
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Nicchia GP, Nico B, Camassa LMA, Mola MG, Loh N, Dermietzel R, Spray DC, Svelto M, Frigeri A. The role of aquaporin-4 in the blood-brain barrier development and integrity: studies in animal and cell culture models. Neuroscience 2005; 129:935-45. [PMID: 15561409 DOI: 10.1016/j.neuroscience.2004.07.055] [Citation(s) in RCA: 157] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2004] [Indexed: 02/09/2023]
Abstract
Aquaporin-4 (AQP4) is the major water channel expressed in brain perivascular astrocyte processes. Although the role of AQP4 in brain edema has been extensively investigated, little information exists regarding its functional role at the blood-brain barrier (BBB). The purpose of this work is to integrate previous and recent data regarding AQP4 expression during BBB formation and depending on BBB integrity, using several experimental models. Results from studies on the chick optic tectum, a well-established model of BBB development, and the effect of lipopolysaccharide on the BBB integrity and on perivascular AQP4 expression have been analyzed and discussed. Moreover, data on the BBB structure and AQP4 expression in murine models of Duchenne muscular dystrophy are reviewed. In particular, published results obtained from mdx(3cv) mice have been analyzed together with new data obtained from mdx mice in which all the dystrophin isoforms including DP71 are strongly reduced. Finally, the role of the endothelial component on AQP4 cellular expression and distribution has been investigated using rat primary astrocytes and brain capillary endothelial cell co-cultures as an in vitro model of BBB.
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Affiliation(s)
- G P Nicchia
- Department of General and Environmental Physiology and Centre of Excellence in Comparative Genomics (CEGBA), University of Bari, via Amendola 165/A, I-70126 Bari, Italy
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19
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Hanson DR, Gottesman II. Theories of schizophrenia: a genetic-inflammatory-vascular synthesis. BMC MEDICAL GENETICS 2005; 6:7. [PMID: 15707482 PMCID: PMC554096 DOI: 10.1186/1471-2350-6-7] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2004] [Accepted: 02/11/2005] [Indexed: 12/13/2022]
Abstract
BACKGROUND Schizophrenia, a relatively common psychiatric syndrome, affects virtually all brain functions yet has eluded explanation for more than 100 years. Whether by developmental and/or degenerative processes, abnormalities of neurons and their synaptic connections have been the recent focus of attention. However, our inability to fathom the pathophysiology of schizophrenia forces us to challenge our theoretical models and beliefs. A search for a more satisfying model to explain aspects of schizophrenia uncovers clues pointing to genetically mediated CNS microvascular inflammatory disease. DISCUSSION A vascular component to a theory of schizophrenia posits that the physiologic abnormalities leading to illness involve disruption of the exquisitely precise regulation of the delivery of energy and oxygen required for normal brain function. The theory further proposes that abnormalities of CNS metabolism arise because genetically modulated inflammatory reactions damage the microvascular system of the brain in reaction to environmental agents, including infections, hypoxia, and physical trauma. Damage may accumulate with repeated exposure to triggering agents resulting in exacerbation and deterioration, or healing with their removal. There are clear examples of genetic polymorphisms in inflammatory regulators leading to exaggerated inflammatory responses. There is also ample evidence that inflammatory vascular disease of the brain can lead to psychosis, often waxing and waning, and exhibiting a fluctuating course, as seen in schizophrenia. Disturbances of CNS blood flow have repeatedly been observed in people with schizophrenia using old and new technologies. To account for the myriad of behavioral and other curious findings in schizophrenia such as minor physical anomalies, or reported decreased rates of rheumatoid arthritis and highly visible nail fold capillaries, we would have to evoke a process that is systemic such as the vascular and immune/inflammatory systems. SUMMARY A vascular-inflammatory theory of schizophrenia brings together environmental and genetic factors in a way that can explain the diversity of symptoms and outcomes observed. If these ideas are confirmed, they would lead in new directions for treatments or preventions by avoiding inducers of inflammation or by way of inflammatory modulating agents, thus preventing exaggerated inflammation and consequent triggering of a psychotic episode in genetically predisposed persons.
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Affiliation(s)
- Daniel R Hanson
- Department of Psychiatry, VA Medical Center (116A), One Veterans Drive, Minneapolis, MN, 55417 and Departments of Psychiatry & Psychology, University of Minnesota, USA
| | - Irving I Gottesman
- Departments of Psychiatry & Psychology, University of Minnesota, Minneapolis, MN 55454, USA
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20
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Ballabh P, Braun A, Nedergaard M. The blood-brain barrier: an overview: structure, regulation, and clinical implications. Neurobiol Dis 2004; 16:1-13. [PMID: 15207256 DOI: 10.1016/j.nbd.2003.12.016] [Citation(s) in RCA: 1495] [Impact Index Per Article: 74.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2003] [Revised: 11/21/2003] [Accepted: 12/10/2003] [Indexed: 02/08/2023] Open
Abstract
The blood-brain barrier (BBB) is a diffusion barrier, which impedes influx of most compounds from blood to brain. Three cellular elements of the brain microvasculature compose the BBB-endothelial cells, astrocyte end-feet, and pericytes (PCs). Tight junctions (TJs), present between the cerebral endothelial cells, form a diffusion barrier, which selectively excludes most blood-borne substances from entering the brain. Astrocytic end-feet tightly ensheath the vessel wall and appear to be critical for the induction and maintenance of the TJ barrier, but astrocytes are not believed to have a barrier function in the mammalian brain. Dysfunction of the BBB, for example, impairment of the TJ seal, complicates a number of neurologic diseases including stroke and neuroinflammatory disorders. We review here the recent developments in our understanding of the BBB and the role of the BBB dysfunction in CNS disease. We have focused on intraventricular hemorrhage (IVH) in premature infants, which may involve dysfunction of the TJ seal as well as immaturity of the BBB in the germinal matrix (GM). A paucity of TJs or PCs, coupled with incomplete coverage of blood vessels by astrocyte end-feet, may account for the fragility of blood vessels in the GM of premature infants. Finally, this review describes the pathogenesis of increased BBB permeability in hypoxia-ischemia and inflammatory mechanisms involving the BBB in septic encephalopathy, HIV-induced dementia, multiple sclerosis, and Alzheimer disease.
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Affiliation(s)
- Praveen Ballabh
- Department of Pediatrics, New York Medical College and Westchester Medical Center, Valhalla, NY 10595, USA.
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21
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Affiliation(s)
- Ondine Cleaver
- Howard Hughes Medical Institute and Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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22
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Omidi Y, Campbell L, Barar J, Connell D, Akhtar S, Gumbleton M. Evaluation of the immortalised mouse brain capillary endothelial cell line, b.End3, as an in vitro blood–brain barrier model for drug uptake and transport studies. Brain Res 2003; 990:95-112. [PMID: 14568334 DOI: 10.1016/s0006-8993(03)03443-7] [Citation(s) in RCA: 187] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Well-characterised cell lines represent important tools for the study of endogenous solute or xenobiotic transport. A brain microvascular cell line, b.End3, isolated from mice transformed with the Polyoma virus middle T-antigen is available commercially. Here we report the characterisation of some features of b.End3 of relevance to its use in blood-brain barrier transport investigations. The b.End3 cells displayed a distinctive spindle-like squamous morphology in culture. Clathrin coated pits and numerous uncoated intracellular vesicles were evident within the cells, as was the expression of the vesicle-associated proteins, clathrin, caveolin-1, flotillin and dynamin II. In the presence of C6 astroglial co-culture b.End3 monolayers achieved a maximal transendothelial electrical resistance of 130 Omega cm2, but lacked real discrimination with respect to the permeation of transcellular and paracellular probes, e.g. permeability coefficients (x 10(-6) cm s(-1)) for propranolol of approximately 23 vs. 16 for sucrose. RT-PCR analysis confirmed the presence within the b.End3 cells of mRNA transcripts for the following transporters: GLUT-1; MCT 1 and 2; OAT1; Oatp1; mdr 1a and 1b; MRP 1 and 5; beta-alanine, system L and system y+L amino acid carriers; the nucleoside transporters cNT1 and 2, eNT1 and 2, and the tight junctional elements, ZO-1, JAM, occludin, claudin-1 and -5. The b.End3 cells actively accumulated D-glucose in a sodium-independent manner with characteristics consistant with that of GLUT-1. Functionality for P-glycoprotein efflux was evident as assessed by a rhodamine-123 accumulation and retention assay. The system L LAT1/4F2hc amino acid transporter was examined through uptake of L-leucine and L-phenylalanine and provided Km and Vmax values of approximately 16 microM and 350-480 pmol/mg protein/10 min, respectively; the affinity of transport for these substrates being weaker, approximately threefold, when the b.End3 cells were grown in the presence of C6 astroglial factors. Although the b.End3 cells appear unsuitable for transendothelial permeability assessments they display characteristics that would allow their worthwhile use in studies addressing blood-brain barrier transport mechanisms.
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Affiliation(s)
- Yadollah Omidi
- Pharmaceutical Cell Biology, Welsh School of Pharmacy, Redwood Building, Cardiff University, Cardiff CF10 3XF, UK
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23
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Park JA, Choi KS, Kim SY, Kim KW. Coordinated interaction of the vascular and nervous systems: from molecule- to cell-based approaches. Biochem Biophys Res Commun 2003; 311:247-53. [PMID: 14592405 DOI: 10.1016/j.bbrc.2003.09.129] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Endothelial cells (ECs) build blood vessels and regulate their plasticity in coordination with neurons. Likewise, neurons construct nerves and regulate their circuits in coordination with ECs. Blood vessel/nerve interactions, ultimately, play essential roles for the neurovascular network and brain function. With conventional molecular approaches, such coordinated interaction is likely due to complex interplay of neuroangiogenic factors and receptors. Aside from molecular regulation of neuroangiogenic factors, currently, cell-based approaches to investigate how blood vessels (or nerves) respond to nerves (or blood vessels) appropriately in the pathophysiological situation are gradually emerging. In order to define responsiveness and flexibility of the neurovascular network in response to the local need, the intercellular communication and coordinated interaction between the vascular and nervous systems need to be thought as a working unit. Based on the scale of the working unit which is in the millimeter range with respect to the physical distance of the neurovascular network, we propose to use a rather conceptual term "Millibiology". The millibiological approach for the coordinated interaction might bring us new paradigm to define neurovascular functions in the pathophysiological state.
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Affiliation(s)
- Jeong-Ae Park
- Research Institute of Pharmaceutical Sciences and College of Pharmacy, Seoul National University, Seoul 151-742, South Korea
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24
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Abstract
Blood vessels perfuse all tissues in the body and mediate vital metabolic exchange between tissues and blood. Increasing evidence, however, points to a direct role for paracrine signaling between blood vessel cells and surrounding target organ cells, during embryonic development and cell differentiation. Understanding the nature of this signaling and its heterogeneity, both in the embryo and in adult tissues, may not only provide insights into mechanisms for normal developmental cell fate decisions, but could also lead to novel targeted therapeutic approaches for a variety of diseases such as heart disease, diabetes or cancer.
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Affiliation(s)
- Ondine Cleaver
- Howard Hughes Medical Institute and Department of Cellular and Molecular Biology, Harvard University, 7 Divinity Ave, Cambridge, Massachusetts 02138, USA.
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