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Rawal SU, Patel BM, Patel MM. New Drug Delivery Systems Developed for Brain Targeting. Drugs 2022; 82:749-792. [PMID: 35596879 DOI: 10.1007/s40265-022-01717-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2022] [Indexed: 11/26/2022]
Abstract
The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSF) are two of the most complex and sophisticated concierges that defend the central nervous system (CNS) by numerous mechanisms. While they maintain the neuro-ecological homeostasis through the regulated entry of essential biomolecules, their conservative nature challenges the entry of most of the drugs intended for CNS delivery. Targeted delivery challenges for a diverse spectrum of therapeutic agents/drugs (non-small molecules, small molecules, gene-based therapeutics, protein and peptides, antibodies) are diverse and demand specialized delivery and disease-targeting strategies. This review aims to capture the trends that have shaped the current brain targeting research scenario. This review discusses the physiological, neuropharmacological, and etiological factors that participate in the transportation of various drug delivery cargoes across the BBB/BCSF and influence their therapeutic intracranial concentrations. Recent research works spanning various invasive, minimally invasive, and non-invasive brain- targeting approaches are discussed. While the pre-clinical outcomes from many of these approaches seem promising, further research is warranted to overcome the translational glitches that prevent their clinical use. Non-invasive approaches like intranasal administration, P-glycoprotein (P-gp) inhibition, pro-drugs, and carrier/targeted nanocarrier-aided delivery systems (alone or often in combination) hold positive clinical prospects for brain targeting if explored further in the right direction.
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Affiliation(s)
- Shruti U Rawal
- Department of Pharmaceutics, Institute of Pharmacy, Nirma University, SG Highway, Chharodi, Ahmedabad, Gujarat, 382481, India
- Department of Pharmaceutical Technology, L.J. Institute of Pharmacy, L J University, Sarkhej-Sanand Circle Off. S.G. Road, Ahmedabad, Gujarat, 382210, India
| | - Bhoomika M Patel
- Department of Pharmacology, Institute of Pharmacy, Nirma University, SG Highway, Chharodi, Ahmedabad, Gujarat, 382481, India
| | - Mayur M Patel
- Department of Pharmaceutics, Institute of Pharmacy, Nirma University, SG Highway, Chharodi, Ahmedabad, Gujarat, 382481, India.
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Hypoxia increases expression of selected blood-brain barrier transporters GLUT-1, P-gp, SLC7A5 and TFRC, while maintaining barrier integrity, in brain capillary endothelial monolayers. Fluids Barriers CNS 2022; 19:1. [PMID: 34983574 PMCID: PMC8725498 DOI: 10.1186/s12987-021-00297-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 12/15/2021] [Indexed: 01/01/2023] Open
Abstract
Background Brain capillary endothelial cells (BCECs) experience hypoxic conditions during early brain development. The newly formed capillaries are tight and functional before astrocytes and pericytes join the capillaries and establish the neurovascular unit. Brain endothelial cell phenotype markers P-gp (ABCB1), LAT-1(SLC7A5), GLUT-1(SLC2A1), and TFR(TFRC) have all been described to be hypoxia sensitive. Therefore, we hypothesized that monolayers of BCECs, cultured under hypoxic conditions, would show an increase in LAT-1, GLUT-1 and TFR expression and display tight endothelial barriers. Methods and results Primary bovine BCECs were cultured under normoxic and hypoxic conditions. Chronic hypoxia induced HIF-1α stabilization and translocation to the nucleus, as judged by immunocytochemistry and confocal laser scanning imaging. Endothelial cell morphology, claudin-5 and ZO-1 localization and barrier integrity were unaffected by hypoxia, indicating that the tight junctions in the BBB model were not compromised. SLC7A5, SLC2A1, and TFRC-mRNA levels were increased in hypoxic cultures, while ABCB1 remained unchanged as shown by real-time qPCR. P-gp, TfR and GLUT-1 were found to be significantly increased at protein levels. An increase in uptake of [3H]-glucose was demonstrated, while a non-significant increase in the efflux ratio of the P-gp substrate [3H]-digoxin was observed in hypoxic cells. No changes were observed in functional LAT-1 as judged by uptake studies of [3H]-leucine. Stabilization of HIF-1α under normoxic conditions with desferrioxamine (DFO) mimicked the effects of hypoxia on endothelial cells. Furthermore, low concentrations of DFO caused an increase in transendothelial electrical resistance (TEER), suggesting that a slight activation of the HIF-1α system may actually increase brain endothelial monolayer tightness. Moreover, exposure of confluent monolayers to hypoxia resulted in markedly increase in TEER after 24 and 48 h, which corresponded to a higher transcript level of CLDN5. Conclusions Our findings collectively suggest that hypoxic conditions increase some BBB transporters' expression via HIF-1α stabilization, without compromising monolayer integrity. This may in part explain why brain capillaries show early maturation, in terms of barrier tightness and protein expression, during embryogenesis, and provides a novel methodological tool for optimal brain endothelial culture. Supplementary Information The online version contains supplementary material available at 10.1186/s12987-021-00297-6.
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Shi L, Jiang M, Li M, Shang X, Li X, Huang M, Wu Y, Qiao C, Wang X, Tian X, Shi Y, Wang Z. Regulation of HIF-1α and p53 in stress responses in the subterranean rodents Lasiopodomys mandarinus and Lasiopodomys brandtii (Rodentia: Cricetidae). ZOOLOGIA 2021. [DOI: 10.3897/zoologia.38.e58607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The response mechanism and interaction patterns of HIF-1α and p53 in animals in an hypoxic environment are crucial for their hypoxic tolerance and adaptation. Many studies have shown that underground rodents have better hypoxic adaptation characteristics. However, the mechanism by which HIF-1α and p53 in underground rodents respond to hypoxic environments compared with in ground rodents remains unclear. Further, whether a synergy between HIF-1α and p53 enables animals tolerate extremely hypoxic environments is unclear. We studied HIF-1α and p53 expression in the brain tissue and cell apoptosis in the hippocampal CA1 region during 6 hours of acute hypoxia (5% oxygen) in Lasiopodomys mandarinus (Milne-Edwards, 1871) and Lasiopodomys brandtii (Radde, 1861), two closely related small rodents with different life characteristics (underground and aboveground, respectively), using a comparative biology method to determine the mechanisms underlying their adaptation to this environment. Our results indicate that HIF-1α and p53 expression is more rapid in L. mandarinus than in L. brandtii under acute hypoxic environments, resulting in a significant synergistic effect in L. mandarinus. Correlation analysis revealed that HIF-1α expression and the apoptotic index of the hippocampal CA1 regions of the brain tissues of L. mandarinus and L. brandtii, both under hypoxia, were significantly negatively and positively correlated, respectively. Long-term existence in underground burrow systems could enable better adaptation to hypoxia in L. mandarinus than in L. brandtii. We speculate that L. mandarinus can quickly eliminate resulting damage via the synergistic effect of p53 and HIF-1α in response to acute hypoxic environments, helping the organism quickly return to a normal state after the stress.
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Ding S, Khan AI, Cai X, Song Y, Lyu Z, Du D, Dutta P, Lin Y. Overcoming blood-brain barrier transport: Advances in nanoparticle-based drug delivery strategies. MATERIALS TODAY (KIDLINGTON, ENGLAND) 2020; 37:112-125. [PMID: 33093794 PMCID: PMC7575138 DOI: 10.1016/j.mattod.2020.02.001] [Citation(s) in RCA: 179] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The Blood-Brain Barrier (BBB), a unique structure in the central nervous system (CNS), protects the brain from bloodborne pathogens by its excellent barrier properties. Nevertheless, this barrier limits therapeutic efficacy and becomes one of the biggest challenges in new drug development for neurodegenerative disease and brain cancer. Recent breakthroughs in nanotechnology have resulted in various nanoparticles (NPs) as drug carriers to cross the BBB by different methods. This review presents the current understanding of advanced NP-mediated non-invasive drug delivery for the treatment of neurological disorders. Herein, the complex compositions and special characteristics of BBB are elucidated exhaustively. Moreover, versatile drug nanocarriers with their recent applications and their pathways on different drug delivery strategies to overcome the formidable BBB obstacle are briefly discussed. In terms of significance, this paper provides a general understanding of how various properties of nanoparticles aid in drug delivery through BBB and usher the development of novel nanotechnology-based nanomaterials for cerebral disease therapies.
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Affiliation(s)
| | | | - Xiaoli Cai
- School of Mechanical and Materials Engineering, Washington State University, PO Box 642920 Pullman, Washington 99164, United States
| | - Yang Song
- School of Mechanical and Materials Engineering, Washington State University, PO Box 642920 Pullman, Washington 99164, United States
| | - Zhaoyuan Lyu
- School of Mechanical and Materials Engineering, Washington State University, PO Box 642920 Pullman, Washington 99164, United States
| | - Dan Du
- School of Mechanical and Materials Engineering, Washington State University, PO Box 642920 Pullman, Washington 99164, United States
| | - Prashanta Dutta
- School of Mechanical and Materials Engineering, Washington State University, PO Box 642920 Pullman, Washington 99164, United States
| | - Yuehe Lin
- School of Mechanical and Materials Engineering, Washington State University, PO Box 642920 Pullman, Washington 99164, United States
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Yang WT, Wang Y, Shi YH, Fu H, Xu Z, Xu QQ, Zheng GQ. Herbal Compatibility of Ginseng and Rhubarb Exerts Synergistic Neuroprotection in Cerebral Ischemia/Reperfusion Injury of Rats. Front Physiol 2019; 10:1174. [PMID: 31572219 PMCID: PMC6753204 DOI: 10.3389/fphys.2019.01174] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/30/2019] [Indexed: 12/12/2022] Open
Abstract
Objective Ischemic stroke is a complex multifactorial disease caused by interactions among polygenetic, environmental, and lifestyle factors with limited effective treatments. Multi-herbal formulae have long been used for stroke through herbal compatibility in traditional Chinese medicine (TCM); however, there is still a lack of evidence due to their unimaginable complexity. Herbal pairs represent the simplest and basic features of multi-herbal formulae, which are of great significance in clarifying herbal compatibility. Here, we aim to investigate the neuroprotective effects of the herbal compatibility of Ginseng and Rhubarb on a cerebral ischemia/reperfusion (I/R) injury model of rats. Methods Male adult SD rats were randomly divided into a sham group, a normal saline (NS) group, a Ginseng group, a Rhubarb group, and a Ginseng + Rhubarb (GR) group, a Carbenoxolone [CBX, gap junction (GJ) specific inhibitor] group, and a GR + CBX group. Each group was further assigned into four subgroups according to ischemic time (6 h, 1 day, 3 days, and 7 days). The cerebral I/R injury model was established according to the modified Zea Longa method. The Neurological Deficiency Score (NDS) was assessed by the Zea-Longa scale; the cerebral infarction area was detected by TTC (2,3,5-triphenyltetrazolium chloride) staining; and the expression of connexin-43 (Cx43) and aquaporin-4 (AQP4) were detected based on an immunofluorescence technique and quantitative real-time-PCR. Results Compared to the I/R group, both the independent and combined use of Ginseng and Rhubarb can significantly improve NDS (P < 0.05), decrease the percentage of the cerebral infarction area around the infarction penumbra (P < 0.05) and down-regulate the expression of Cx43 and AQP4 after I/R injury (P < 0.05). The GR had more significant effects than that of Ginseng and Rhubarb (P < 0.05). Compared with the GR group, the GR + CBX group significantly improved in NDS (P < 0.05), and decreased the percentage of the cerebral infarction area (P < 0.05) and expression of Cx43 and AQP4 protein (P < 0.05). Conclusion The herbal compatibility of Ginseng and Rhubarb synergistically exerts neuroprotective function during acute cerebral I/R injury, mainly through reducing the expression of Cx43 and AQP4.
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Affiliation(s)
- Wen-Ting Yang
- Department of Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yong Wang
- Department of Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yi-Hua Shi
- Department of Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Huan Fu
- Department of Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhen Xu
- Department of Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Qing-Qing Xu
- Department of Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Guo-Qing Zheng
- Department of Neurology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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Li Y, Zhu ZY, Huang TT, Zhou YX, Wang X, Yang LQ, Chen ZA, Yu WF, Li PY. The peripheral immune response after stroke-A double edge sword for blood-brain barrier integrity. CNS Neurosci Ther 2018; 24:1115-1128. [PMID: 30387323 PMCID: PMC6490160 DOI: 10.1111/cns.13081] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 10/09/2018] [Accepted: 10/09/2018] [Indexed: 02/07/2023] Open
Abstract
The blood‐brain barrier (BBB) is a highly regulated interface that separates the peripheral circulation and the brain. It plays a vital role in regulating the trafficking of solutes, fluid, and cells at the blood‐brain interface and maintaining the homeostasis of brain microenvironment for normal neuronal activity. Growing evidence has led to the realization that ischemic stroke elicits profound immune responses in the circulation and the activation of multiple subsets of immune cells, which in turn affect both the early disruption and the later repair of the BBB after stroke. Distinct phenotypes or subsets of peripheral immune cells along with diverse intracellular mechanisms contribute to the dynamic changes of BBB integrity after stroke. This review focuses on the interaction between the peripheral immune cells and the BBB after ischemic stroke. Understanding their reciprocal interaction may generate new directions for stroke research and may also drive the innovation of easy accessible immune modulatory treatment strategies targeting BBB in the pursuit of better stroke recovery.
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Affiliation(s)
- Yan Li
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Zi-Yu Zhu
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Ting-Ting Huang
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yu-Xi Zhou
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Xin Wang
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Li-Qun Yang
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Zeng-Ai Chen
- Department of Radiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Wei-Feng Yu
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Pei-Ying Li
- Department of Anesthesiology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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Al-Ahmad AJ. Comparative study of expression and activity of glucose transporters between stem cell-derived brain microvascular endothelial cells and hCMEC/D3 cells. Am J Physiol Cell Physiol 2017; 313:C421-C429. [PMID: 28993322 DOI: 10.1152/ajpcell.00116.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 07/28/2017] [Accepted: 07/28/2017] [Indexed: 12/22/2022]
Abstract
Glucose constitutes a major source of energy of mammalian brains. Glucose uptake at the blood-brain barrier (BBB) occurs through a facilitated glucose transport, through glucose transporter 1 (GLUT1), although other isoforms have been described at the BBB. Mutations in GLUT1 are associated with the GLUT1 deficiency syndrome, yet none of the current in vitro models of the human BBB maybe suited for modeling such a disorder. In this study, we investigated the expression of glucose transporters and glucose diffusion across brain microvascular endothelial cells (BMECs) derived from healthy patient-derived induced pluripotent stem cells (iPSCs). We investigated the expression of different glucose transporters at the BBB using immunocytochemistry and flow cytometry and measured glucose uptake and diffusion across BMEC monolayers obtained from two iPSC lines and from hCMEC/D3 cells. BMEC monolayers showed expression of several glucose transporters, in particular GLUT1, GLUT3, and GLUT4. Diffusion of glucose across the monolayers was mediated via a saturable transcellular mechanism and partially inhibited by pharmacological inhibitors. Taken together, our study suggests the presence of several glucose transporters isoforms at the human BBB and demonstrates the feasibility of modeling glucose across the BBB using patient-derived stem cells.
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Affiliation(s)
- Abraham J Al-Ahmad
- Texas Tech University Health Sciences Center, School of Pharmacy, Department of Pharmaceutical Sciences, Amarillo, Texas
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Tornabene E, Brodin B. Stroke and Drug Delivery--In Vitro Models of the Ischemic Blood-Brain Barrier. J Pharm Sci 2016; 105:398-405. [PMID: 26869407 DOI: 10.1016/j.xphs.2015.11.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/20/2015] [Accepted: 11/20/2015] [Indexed: 12/11/2022]
Abstract
Stroke is a major cause of death and disability worldwide. Both cerebral hypoperfusion and focal cerebral infarcts are caused by a reduction of blood flow to the brain, leading to stroke and subsequent brain damage. At present, only few medical treatments of stroke are available, with the Food and Drug Administration-approved tissue plasminogen activator for treatment of acute ischemic stroke being the most prominent example. A large number of potential drug candidates for treatment of ischemic brain tissue have been developed and subsequently failed in clinical trials. A deeper understanding of permeation pathways across the barrier in ischemic and postischemic brain endothelium is important for development of new medical treatments. The blood-brain barrier, that is, the endothelial monolayer lining the brain capillaries, changes properties during an ischemic event. In vitro models of the blood-brain barrier are useful tools to investigate the effects of induced ischemia under controlled conditions. In the present mini review, we aim to give a brief overview of the in vitro models of ischemia. Special focus is given to the expression of uptake and efflux transport pathways in the ischemic and postischemic endothelium. Finally, we will point toward future challenges within the field of in vitro models of brain ischemia.
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Affiliation(s)
- Erica Tornabene
- Section of Pharmaceutical Design and Drug Delivery, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Birger Brodin
- Section of Pharmaceutical Design and Drug Delivery, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark.
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Helms HC, Abbott NJ, Burek M, Cecchelli R, Couraud PO, Deli MA, Förster C, Galla HJ, Romero IA, Shusta EV, Stebbins MJ, Vandenhaute E, Weksler B, Brodin B. In vitro models of the blood-brain barrier: An overview of commonly used brain endothelial cell culture models and guidelines for their use. J Cereb Blood Flow Metab 2016; 36:862-90. [PMID: 26868179 PMCID: PMC4853841 DOI: 10.1177/0271678x16630991] [Citation(s) in RCA: 515] [Impact Index Per Article: 64.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 01/05/2016] [Indexed: 12/12/2022]
Abstract
The endothelial cells lining the brain capillaries separate the blood from the brain parenchyma. The endothelial monolayer of the brain capillaries serves both as a crucial interface for exchange of nutrients, gases, and metabolites between blood and brain, and as a barrier for neurotoxic components of plasma and xenobiotics. This "blood-brain barrier" function is a major hindrance for drug uptake into the brain parenchyma. Cell culture models, based on either primary cells or immortalized brain endothelial cell lines, have been developed, in order to facilitate in vitro studies of drug transport to the brain and studies of endothelial cell biology and pathophysiology. In this review, we aim to give an overview of established in vitro blood-brain barrier models with a focus on their validation regarding a set of well-established blood-brain barrier characteristics. As an ideal cell culture model of the blood-brain barrier is yet to be developed, we also aim to give an overview of the advantages and drawbacks of the different models described.
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Affiliation(s)
- Hans C Helms
- Department of Pharmacy, University of Copenhagen, Denmark
| | - N Joan Abbott
- Institute of Pharmaceutical Science, King's College London, UK
| | - Malgorzata Burek
- Klinik und Poliklinik für Anästhesiologie, University of Wurzburg, Germany
| | | | - Pierre-Olivier Couraud
- Institut Cochin, INSERM U1016, CNRS UMR8104, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Maria A Deli
- Institute of Biophysics, Biological Research Centre, HAS, Szeged, Hungary
| | - Carola Förster
- Klinik und Poliklinik für Anästhesiologie, University of Wurzburg, Germany
| | - Hans J Galla
- Institute of Biochemistry, University of Muenster, Germany
| | - Ignacio A Romero
- Department of Biological Sciences, The Open University, Walton Hall, Milton Keynes, UK
| | - Eric V Shusta
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, WI, USA
| | - Matthew J Stebbins
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, WI, USA
| | | | - Babette Weksler
- Division of Hematology and Medical Oncology, Weill Cornell Medical College, NY, USA
| | - Birger Brodin
- Department of Pharmacy, University of Copenhagen, Denmark
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Grabrucker AM, Ruozi B, Belletti D, Pederzoli F, Forni F, Vandelli MA, Tosi G. Nanoparticle transport across the blood brain barrier. Tissue Barriers 2016; 4:e1153568. [PMID: 27141426 DOI: 10.1080/21688370.2016.1153568] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 02/02/2016] [Accepted: 02/04/2016] [Indexed: 01/13/2023] Open
Abstract
While the role of the blood-brain barrier (BBB) is increasingly recognized in the (development of treatments targeting neurodegenerative disorders, to date, few strategies exist that enable drug delivery of non-BBB crossing molecules directly to their site of action, the brain. However, the recent advent of Nanomedicines may provide a potent tool to implement CNS targeted delivery of active compounds. Approaches for BBB crossing are deeply investigated in relation to the pathology: among the main important diseases of the CNS, this review focuses on the application of nanomedicines to neurodegenerative disorders (Alzheimer, Parkinson and Huntington's Disease) and to other brain pathologies as epilepsy, infectious diseases, multiple sclerosis, lysosomal storage disorders, strokes.
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Affiliation(s)
- Andreas M Grabrucker
- WG Molecular Analysis of Synaptopathies, Neurology Dept, Neurocenter of Ulm University , Ulm, Germany
| | - Barbara Ruozi
- Pharmaceutical Technology, Te.Far.T.I. Group, Department of Life Sciences, University of Modena and Reggio Emilia ; Modena, Italy
| | - Daniela Belletti
- Pharmaceutical Technology, Te.Far.T.I. Group, Department of Life Sciences, University of Modena and Reggio Emilia ; Modena, Italy
| | - Francesca Pederzoli
- Pharmaceutical Technology, Te.Far.T.I. Group, Department of Life Sciences, University of Modena and Reggio Emilia ; Modena, Italy
| | - Flavio Forni
- Pharmaceutical Technology, Te.Far.T.I. Group, Department of Life Sciences, University of Modena and Reggio Emilia ; Modena, Italy
| | - Maria Angela Vandelli
- Pharmaceutical Technology, Te.Far.T.I. Group, Department of Life Sciences, University of Modena and Reggio Emilia ; Modena, Italy
| | - Giovanni Tosi
- Pharmaceutical Technology, Te.Far.T.I. Group, Department of Life Sciences, University of Modena and Reggio Emilia ; Modena, Italy
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Wang Y, Reis C, Applegate R, Stier G, Martin R, Zhang JH. Ischemic conditioning-induced endogenous brain protection: Applications pre-, per- or post-stroke. Exp Neurol 2015; 272:26-40. [PMID: 25900056 DOI: 10.1016/j.expneurol.2015.04.009] [Citation(s) in RCA: 318] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 04/06/2015] [Accepted: 04/11/2015] [Indexed: 11/17/2022]
Abstract
In the area of brain injury and neurodegenerative diseases, a plethora of experimental and clinical evidence strongly indicates the promise of therapeutically exploiting the endogenous adaptive system at various levels like triggers, mediators and the end-effectors to stimulate and mobilize intrinsic protective capacities against brain injuries. It is believed that ischemic pre-conditioning and post-conditioning are actually the strongest known interventions to stimulate the innate neuroprotective mechanism to prevent or reverse neurodegenerative diseases including stroke and traumatic brain injury. Recently, studies showed the effectiveness of ischemic per-conditioning in some organs. Therefore the term ischemic conditioning, including all interventions applied pre-, per- and post-ischemia, which spans therapeutic windows in 3 time periods, has recently been broadly accepted by scientific communities. In addition, it is extensively acknowledged that ischemia-mediated protection not only affects the neurons but also all the components of the neurovascular network (consisting of neurons, glial cells, vascular endothelial cells, pericytes, smooth muscle cells, and venule/veins). The concept of cerebroprotection has been widely used in place of neuroprotection. Intensive studies on the cellular signaling pathways involved in ischemic conditioning have improved the mechanistic understanding of tolerance to cerebral ischemia. This has added impetus to exploration for potential pharmacologic mimetics, which could possibly induce and maximize inherent protective capacities. However, most of these studies were performed in rodents, and the efficacy of these mimetics remains to be evaluated in human patients. Several classical signaling pathways involving apoptosis, inflammation, or oxidation have been elaborated in the past decades. Newly characterized mechanisms are emerging with the advances in biotechnology and conceptual renewal. In this review we are going to focus on those recently reported methodological and mechanistic discoveries in the realm of ischemic conditioning. Due to the varied time differences of ischemic conditioning in different animal models and clinical trials, it is important to define optimal timing to achieve the best conditioning induced neuroprotection. This brings not only an opportunity in the treatment of stroke, but challenges as well, as data is just becoming available and the procedures are not yet optimized. The purpose of this review is to shed light on exploiting these ischemic conditioning modalities to protect the cerebrovascular system against diverse injuries and neurodegenerative disorders.
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Affiliation(s)
- Yuechun Wang
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, USA; Department of Physiology, Jinan University School of Medicine, Guangzhou, China
| | - Cesar Reis
- Department of Anesthesiology, Loma Linda University Medical Center, Loma Linda, CA, USA
| | - Richard Applegate
- Department of Anesthesiology, Loma Linda University Medical Center, Loma Linda, CA, USA
| | - Gary Stier
- Department of Anesthesiology, Loma Linda University Medical Center, Loma Linda, CA, USA
| | - Robert Martin
- Department of Anesthesiology, Loma Linda University Medical Center, Loma Linda, CA, USA
| | - John H Zhang
- Department of Physiology and Pharmacology, Loma Linda University School of Medicine, Loma Linda, USA; Department of Neurosurgery, Loma Linda University School of Medicine, Loma Linda, USA; Department of Anesthesiology, Loma Linda University Medical Center, Loma Linda, CA, USA.
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Zhang J, Shemezis JR, McQuinn ER, Wang J, Sverdlov M, Chenn A. AKT activation by N-cadherin regulates beta-catenin signaling and neuronal differentiation during cortical development. Neural Dev 2013; 8:7. [PMID: 23618343 PMCID: PMC3658902 DOI: 10.1186/1749-8104-8-7] [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: 10/17/2012] [Accepted: 04/05/2013] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND During cerebral cortical development, neural precursor-precursor interactions in the ventricular zone neurogenic niche coordinate signaling pathways that regulate proliferation and differentiation. Previous studies with shRNA knockdown approaches indicated that N-cadherin adhesion between cortical precursors regulates β-catenin signaling, but the underlying mechanisms remained poorly understood. RESULTS Here, with conditional knockout approaches, we find further supporting evidence that N-cadherin maintains β-catenin signaling during cortical development. Using shRNA to N-cadherin and dominant negative N-cadherin overexpression in cell culture, we find that N-cadherin regulates Wnt-stimulated β-catenin signaling in a cell-autonomous fashion. Knockdown or inhibition of N-cadherin with function-blocking antibodies leads to reduced activation of the Wnt co-receptor LRP6. We also find that N-cadherin regulates β-catenin via AKT, as reduction of N-cadherin causes decreased AKT activation and reduced phosphorylation of AKT targets GSK3β and β-catenin. Inhibition of AKT signaling in neural precursors in vivo leads to reduced β-catenin-dependent transcriptional activation, increased migration from the ventricular zone, premature neuronal differentiation, and increased apoptotic cell death. CONCLUSIONS These results show that N-cadherin regulates β-catenin signaling through both Wnt and AKT, and suggest a previously unrecognized role for AKT in neuronal differentiation and cell survival during cortical development.
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Affiliation(s)
- Jianing Zhang
- Department of Pathology, University of Illinois, 909 S, Wolcott Ave., Chicago, IL 60612, USA
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13
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Bahjat FR, Gesuete R, Stenzel-Poore MP. Steps to translate preconditioning from basic research to the clinic. Transl Stroke Res 2012; 4:89-103. [PMID: 23504609 DOI: 10.1007/s12975-012-0223-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Efforts to treat cardiovascular and cerebrovascular diseases often focus on the mitigation of ischemia-reperfusion (I/R) injury. Many treatments or "preconditioners" are known to provide substantial protection against the I/R injury when administered prior to the event. Brief periods of ischemia itself have been validated as a means to achieve neuroprotection in many experimental disease settings, in multiple organ systems, and in multiple species suggesting a common pathway leading to tolerance. In addition, pharmacological agents that act as potent preconditioners have been described. Experimental induction of neuroprotection using these various preconditioning paradigms has provided a unique window into the brain's endogenous protective mechanisms. Moreover, preconditioning agents themselves hold significant promise as clinical-stage therapies for prevention of I/R injury. The aim of this article is to explore several key steps involved in the preclinical validation of preconditioning agents prior to the conduct of clinical studies in humans. Drug development is difficult, expensive and relies on multi-factorial analysis of data from diverse disciplines. Importantly, there is no single path for the preclinical development of a novel therapeutic and no proven strategy to ensure success in clinical translation. Rather, the conduct of a diverse array of robust preclinical studies reduces the risk of clinical failure by varying degrees depending upon the relevance of preclinical models and drug pharmacology to humans. A strong sense of urgency and high tolerance of failure are often required to achieve success in the development of novel treatment paradigms for complex human conditions.
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Affiliation(s)
- Frances R Bahjat
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon
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14
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Baeten KM, Akassoglou K. Extracellular matrix and matrix receptors in blood-brain barrier formation and stroke. Dev Neurobiol 2012; 71:1018-39. [PMID: 21780303 DOI: 10.1002/dneu.20954] [Citation(s) in RCA: 267] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The blood-brain barrier (BBB) is formed primarily to protect the brain microenvironment from the influx of plasma components, which may disturb neuronal functions. The BBB is a functional unit that consists mainly of specialized endothelial cells (ECs) lining the cerebral blood vessels, astrocytes, and pericytes. The BBB is a dynamic structure that is altered in neurologic diseases, such as stroke. ECs and astrocytes secrete extracellular matrix (ECM) proteins to generate and maintain the basement membranes (BMs). ECM receptors, such as integrins and dystroglycan, are also expressed at the brain microvasculature and mediate the connections between cellular and matrix components in physiology and disease. ECM proteins and receptors elicit diverse molecular signals that allow cell adaptation to environmental changes and regulate growth and cell motility. The composition of the ECM is altered upon BBB disruption and directly affects the progression of neurologic disease. The purpose of this review is to discuss the dynamic changes of ECM composition and integrin receptor expression that control BBB functions in physiology and pathology.
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Affiliation(s)
- Kim M Baeten
- Gladstone Institute of Neurological Disease, University of California, San Francisco, California 94158, USA
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15
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Cardoso FL, Kittel Á, Veszelka S, Palmela I, Tóth A, Brites D, Deli MA, Brito MA. Exposure to lipopolysaccharide and/or unconjugated bilirubin impair the integrity and function of brain microvascular endothelial cells. PLoS One 2012; 7:e35919. [PMID: 22586454 PMCID: PMC3346740 DOI: 10.1371/journal.pone.0035919] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 03/27/2012] [Indexed: 11/21/2022] Open
Abstract
Background Sepsis and jaundice are common conditions in newborns that can lead to brain damage. Though lipopolysaccharide (LPS) is known to alter the integrity of the blood-brain barrier (BBB), little is known on the effects of unconjugated bilirubin (UCB) and even less on the joint effects of UCB and LPS on brain microvascular endothelial cells (BMEC). Methodology/Principal Findings Monolayers of primary rat BMEC were treated with 1 µg/ml LPS and/or 50 µM UCB, in the presence of 100 µM human serum albumin, for 4 or 24 h. Co-cultures of BMEC with astroglial cells, a more complex BBB model, were used in selected experiments. LPS led to apoptosis and UCB induced both apoptotic and necrotic-like cell death. LPS and UCB led to inhibition of P-glycoprotein and activation of matrix metalloproteinases-2 and -9 in mono-cultures. Transmission electron microscopy evidenced apoptotic bodies, as well as damaged mitochondria and rough endoplasmic reticulum in BMEC by either insult. Shorter cell contacts and increased caveolae-like invaginations were noticeable in LPS-treated cells and loss of intercellular junctions was observed upon treatment with UCB. Both compounds triggered impairment of endothelial permeability and transendothelial electrical resistance both in mono- and co-cultures. The functional changes were confirmed by alterations in immunostaining for junctional proteins β-catenin, ZO-1 and claudin-5. Enlargement of intercellular spaces, and redistribution of junctional proteins were found in BMEC after exposure to LPS and UCB. Conclusions LPS and/or UCB exert direct toxic effects on BMEC, with distinct temporal profiles and mechanisms of action. Therefore, the impairment of brain endothelial integrity upon exposure to these neurotoxins may favor their access to the brain, thus increasing the risk of injury and requiring adequate clinical management of sepsis and jaundice in the neonatal period.
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Affiliation(s)
- Filipa L. Cardoso
- Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
| | - Ágnes Kittel
- Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| | - Szilvia Veszelka
- Laboratory of Molecular Neurobiology, Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Inês Palmela
- Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
| | - Andrea Tóth
- Laboratory of Molecular Neurobiology, Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Dora Brites
- Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
| | - Mária A. Deli
- Laboratory of Molecular Neurobiology, Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Maria A. Brito
- Research Institute for Medicines and Pharmaceutical Sciences, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
- Department of Biochemistry and Human Biology, Faculty of Pharmacy, University of Lisbon, Lisbon, Portugal
- * E-mail:
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16
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Zhang WJ, Feng J, Zhou R, Ye LY, Liu HL, Peng L, Lou JN, Li CH. Tanshinone IIA protects the human blood-brain barrier model from leukocyte-associated hypoxia-reoxygenation injury. Eur J Pharmacol 2010; 648:146-52. [PMID: 20826144 DOI: 10.1016/j.ejphar.2010.08.040] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 07/21/2010] [Accepted: 08/25/2010] [Indexed: 12/11/2022]
Abstract
To investigate the in vitro effect of tanshinone IIA on leukocyte-associated hypoxia-reoxygenation injury of human brain-blood barrier (BBB), we established the BBB model by culturing purified primary human brain microvascular endothelial cells (HBMVEC) to confluence on cell culture insert. BBB was identified by tight junction, transendothelial electrical resistance (TEER) and the permeability of BBB to horseradish peroxidase (HRP). The effect of tanshinone IIA on the permeability of BBB was tested at 2 h after hypoxia and 1h after reoxygenation with or without the supernatants of activated leukocytes. The effect of tanshinone IIA on leukocytes activation was analyzed by detection of MMP-9, cytokines and reactive oxygen species. The results showed that BBB formed by confluent HBMVECs had no cellular gap. Immunofluorescent staining for ZO-1 confirmed that the cells were connected by tight junction. Moreover, the BBB model had a higher TEER and a lower permeability for HRP than confluent HUVECs. The permeability of BBB for HRP was enhanced by hypoxia-reoxygenation and further greatly enhanced by adding the supernatants of activated leukocytes before reoxygenation. But such an effect was reversed by addition of tanshinone IIA before hypoxia. Moreover, tanshinone IIA could decrease the levels of MMP-9, TNF-α, IL-1α, IL-2, IFN-γ and reactive oxygen species in leukocytes. In conclusion, tanshinone IIA can protect BBB against leukocyte-associated hypoxia-reoxygenation injury by attenuating the activation of leukocytes and inhibiting the injury effects of leukocytic products. Tanshinone IIA may be a novel therapeutic agent for cerebral ischemia-reperfusion injury.
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Affiliation(s)
- Wen-jian Zhang
- Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, PR China
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17
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Hultman K, Björklund U, Hansson E, Jern C. Potentiating effect of endothelial cells on astrocytic plasminogen activator inhibitor type-1 gene expression in an in vitro model of the blood–brain barrier. Neuroscience 2010; 166:408-15. [DOI: 10.1016/j.neuroscience.2010.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 12/10/2009] [Accepted: 01/03/2010] [Indexed: 10/20/2022]
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18
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Kim BJ, Lee SH, Ryu WS, Kang BS, Kim CK, Yoon BW. Low level of low-density lipoprotein cholesterol increases hemorrhagic transformation in large artery atherothrombosis but not in cardioembolism. Stroke 2009; 40:1627-32. [PMID: 19286585 DOI: 10.1161/strokeaha.108.539643] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE Low cholesterol level is known to be associated with increased cerebral hemorrhage. However, the associations of hemorrhagic transformation (HTf) after acute ischemic stroke and the low levels of total cholesterol (TC) or low-density lipoprotein cholesterol (LDLC) are largely undiscovered. METHODS Of the 1034 patients with acute ischemic stroke who were consecutively admitted to our hospital, 377 patients with stroke attributable to large artery atherothrombosis (LAA; n=210) or cardioembolism (n=167) were selected for this study. Demographic and clinical information was collected and HTf was evaluated through follow-up T2*-weighted gradient-echo MRI performed usually within 1 week after stroke. Measurement of lipid parameters included TC, LDLC, high-density lipoprotein cholesterol, and triglyceride. RESULTS Of the 377 patients, HTf was noted in 74 patients (19.6%). When patients were divided into 4 groups according to their TC and LDLC levels, the incidence of HTf was significantly elevated in the lowest quartile of each TC (P<0.01) and LDLC (P<0.01) level in LAA subgroup, but not in cardioembolism. After adjusting covariates, a low level of LDLC (OR, 0.46 per 1 mmol/L-increase; 95% CI, 0.22-0.98) was independently associated with HTf in LAA, but not in cardioembolism. There was no significant association between low levels of TC (OR, 0.63 per 1 mmol/L-increase; 95% CI, 0.35-1.15) and HTf in LAA. CONCLUSIONS Low levels of LDLC, and possibly TC, are associated with greater risk of hemorrhagic transformation after acute ischemic stroke attributable to LAA.
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Affiliation(s)
- Beom Joon Kim
- Department of Neurology, Seoul National University Hospital, Jongno-gu, Seoul, Republic of Korea
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19
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Reperfusion injury after stroke: neurovascular proteases and the blood-brain barrier. HANDBOOK OF CLINICAL NEUROLOGY 2008; 92:117-36. [PMID: 18790272 DOI: 10.1016/s0072-9752(08)01906-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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20
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Kaur C, Sivakumar V, Yong Z, Lu J, Foulds WS, Ling EA. Blood–retinal barrier disruption and ultrastructural changes in the hypoxic retina in adult rats: the beneficial effect of melatonin administration. J Pathol 2007; 212:429-39. [PMID: 17582234 DOI: 10.1002/path.2195] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Reactive changes in astrocytes and Müller cells in the retina of adult rats subjected to hypoxia were investigated. Along with this, the integrity of the blood-retinal barrier (BRB) was assessed using fluorescent and electron-dense tracers. In hypoxic rats, mRNA and protein expression of glial fibrillary acidic protein (GFAP) and aquaporin-4 (AQ4) were significantly increased. AQ4 immunoreactive cells were identified as astrocytes and Müller cells by double immunofluorescence labelling. Another alteration in the hypoxic retina was marked reduction in melatonin content compared to controls. In this connection, administration of exogenous melatonin reduced the tissue concentration of vascular endothelial growth factor (VEGF) and nitric oxide (NO); both were elevated in hypoxic rats. A major structural change in the hypoxic retina was swelling of astrocyte and Müller cell processes but this was noticeably attenuated after melatonin administration. Following an intraperitoneal or intravenous injection of rhodamine isothiocyanate (RhIC) or horseradish peroxidase (HRP), leakage of both tracers was observed in the retina in hypoxic rats but not in the controls, indicating that the functional integrity of the BRB is compromised in hypoxia/reoxygenation. It is suggested that enhanced tissue concentration of VEGF and NO production in the hypoxic retina contribute to increased permeability of the retinal blood vessels. The concurrent up-regulation of AQ4, a water-transporting protein, in astrocytes and Müller cells in hypoxia suggests its involvement in oedema formation. Since melatonin effectively reduced the vascular permeability in the retina of hypoxic rats, as evidenced by reduced leakage of RhIC, we suggest that its administration may be of potential benefit in the management of retinal oedema associated with retinal hypoxia.
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Affiliation(s)
- C Kaur
- Department of Anatomy, Yong Loo Lin School of Medicine, Blk MD10, 4 Medical Drive, National University of Singapore, Singapore 117597.
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21
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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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22
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Abstract
The delivery of proteins across the blood-brain barrier is severely limited by their size and biochemical properties. Numerous peptides have been characterized in recent years that prevent neuronal death in vitro, but cannot be used therapeutically, since they do not cross cell membrane barriers. It has been shown in the 1990s that the HIV TAT protein is able to cross cell membranes even when coupled with larger peptides. It appears, therefore, that TAT fusion proteins may enter the brain, even when used systemically. Indeed, the systemic delivery of a TAT protein linked with glial-derived neurotrophic factor (GDNF) successfully transduced central nervous system (CNS) neurons in mice. When administered after optic nerve transection and focal cerebral ischemia, TAT-GDNF protected retinal ganglion cells and brain neurons from cell death, elevated tissue Bcl-XL levels and attenuated the activity of the executioner caspase-3. These findings demonstrate the in vivo efficacy of fusion proteins in clinically relevant disease models, raising hopes that neuroprotection may become eventually feasible in human patients.
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Affiliation(s)
- Ertugrul Kilic
- Department of Neurology, University Hospital Zürich, Frauenklinikstr. 26, CH-8091 Zürich, Switzerland.
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23
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Ding YH, Li J, Yao WX, Rafols JA, Clark JC, Ding Y. Exercise preconditioning upregulates cerebral integrins and enhances cerebrovascular integrity in ischemic rats. Acta Neuropathol 2006; 112:74-84. [PMID: 16703337 DOI: 10.1007/s00401-006-0076-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Revised: 04/17/2006] [Accepted: 04/21/2006] [Indexed: 01/01/2023]
Abstract
We hypothesized that exercise preconditioning strengthens brain microvascular integrity against ischemia/reperfusion injury through the tumor necrosis factor (TNF)-integrin signaling pathway. Adult male Sprague Dawley rats (n = 24) were studied in: (1) exercise (the animals run on a treadmill 30 min each day) for 3 weeks, (2) non-exercise. Six animals from each group (n = 12) were subjected to stroke, the remaining animals served as controls (n = 6 x 2). Brain infarction and edema were determined by Nissl staining. Cerebral integrin expression was detected by immunochemistry and stereological methods. In addition, we used flow cytometry to address the causal role of TNF-alpha in inducing the expression of integrins in the human umbilical vein endothelial cells under TNF-alpha or vascular endothelial growth factor (VEGF) pretreatment. Exercise reduces brain infarction and brain edema in stroke. Expressions of integrin subunit alpha(1), alpha(6), beta(1), and beta(4) were increased after exercise. Exercise preconditioning reversed stroke-reduced integrin expression. An in vitro study revealed a causal link between the gradual upregulation of TNF-alpha (rather than VEGF) and cellular expression of integrins. These results demonstrated an increase in cerebral expression of integrins and a decrease in brain injury from stroke after exercise preconditioning. The study suggests that upregulation of integrins during exercise enhances neurovascular integrity after stroke. The changes in integrins might be altered by TNF-alpha.
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Affiliation(s)
- Y H Ding
- Department of Neurological Surgery, Wayne State University School of Medicine, Detroit, MI, USA
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24
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Dimitrijevic OB, Stamatovic SM, Keep RF, Andjelkovic AV. Effects of the chemokine CCL2 on blood-brain barrier permeability during ischemia-reperfusion injury. J Cereb Blood Flow Metab 2006; 26:797-810. [PMID: 16192992 DOI: 10.1038/sj.jcbfm.9600229] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The chemokine CCL2 is considered as one of the main effectors driving postischemic infiltration of monocytes into the brain parenchyma. New experimental data, however, suggest that CCL2 could also participate in blood-brain barrier (BBB) 'opening' during the transmigration of monocytes. The current study examines the role of CCL2 in regulating BBB permeability after ischemia in vitro. To address this issue, an in vitro BBB model (coculture of astrocytes and brain endothelial cells) was subjected to 5 h of oxygen glucose deprivation, followed by reoxgenation (in vitro ischemia/reperfusion (I/R)) for 0 to 48 h. During reperfusion, there was a biphasic enhancement of barrier permeability, with a 200-fold increase in barrier permeability to FITC-albumin at 6 h and a further period of disruption around 24 h. The latter coincided with increased secretion of CCL2 by both astrocytes and brain endothelial cells and increased levels of the CCL2 receptor, CCR2. Applying antisense oligonucleotide or neutralizing antibody to block CCL2 significantly decreased I/R-induced enhancement of BBB permeability (approximately twofold) and redistribution of tight-junction (TJ) proteins (occludin, zonula occluden-1, 2, claudin-5). Similarly, absence of CCR2 from endothelial cells caused stabilization of TJ complexes and decreased the permeability of brain endothelial barrier during in vitro I/R. These data suggest CCL2/CCR2 has an important role in regulating brain endothelial permeability and might be a potential novel therapeutic target for stroke.
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Affiliation(s)
- Oliver B Dimitrijevic
- Department of Neurosurgery, University of Michigan Medical School, Ann Arbor, Michigan 48109-0532, USA
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Ding YH, Ding Y, Li J, Bessert DA, Rafols JA. Exercise pre-conditioning strengthens brain microvascular integrity in a rat stroke model. Neurol Res 2006; 28:184-9. [PMID: 16551437 DOI: 10.1179/016164106x98053] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Increasing evidence indicates that physical activity reduces brain damage after stroke. The purpose of this study was to determine whether exercise-induced neuroprotection is associated with improved brain integrity in stroke. Adult male Sprague-Dawley rats (3 months old, n=38) exercised on a treadmill, which required repetitive locomotor movement, for 30 minutes each day for 3 weeks. Then, using an intraluminal filament, stroke was induced by either 2 hours middle cerebral artery (MCA) occlusion followed by 24 or 48 hours of reperfusion. Brain damage was determined by evaluating brain infarction and brain edema, as well as ultrastructural alteration in endothelial-matrix-astrocyte interfaces.Pre-ischemic motor exercise significantly (p<0.01) reduced infarct volume in the frontoparietal cortex and the dorsolateral striatum by 79%. By comparing the percentage difference in brain volume between the right (stroke site) and left hemispheres, we demonstrated a significant (p<0.01) reduction in brain edema associated with reduced infarct volume in a 3 week exercise group (Group 1, n=10) and a 3 week exercise plus 3 week rest group (Group 2, n=10). Edema in cortex and striatum was 19 +/- 4% without exercise pre-conditioning (n=10), in contrast to 5 +/- 3% (Group 1) or 6 +/- 4% (Group 2). The thickness of the basal lamina was enhanced by exercise. In ischemic rats without pre-exercise, alterations in microvessel ultrastructure with decreased luminal area, parenchymal edema and swollen astrocyte end-feet, as well as an abnormally thin basal lamina were observed. In contrast, exercise pre-conditioning significantly reduced the ischemic alterations, decreasing brain edema and increasing basal lamina thickness. This study suggests that exercise pre-conditioning reduces brain injury by decreasing cerebral permeability and enhancing brain integrity after stroke. This exercise-induced endogenous neuroprotection could be an effective strategy to ameliorate ischemic brain injury from stroke.
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Affiliation(s)
- Yun-Hong Ding
- Department of Neurosurgery, Wayne State University School of Medicine, USA.
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26
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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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27
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Yenari MA, Xu L, Tang XN, Qiao Y, Giffard RG. Microglia potentiate damage to blood-brain barrier constituents: improvement by minocycline in vivo and in vitro. Stroke 2006; 37:1087-93. [PMID: 16497985 DOI: 10.1161/01.str.0000206281.77178.ac] [Citation(s) in RCA: 285] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Blood-brain barrier (BBB) disruption after stroke can worsen ischemic injury by increasing edema and causing hemorrhage. We determined the effect of microglia on the BBB and its primary constituents, endothelial cells (ECs) and astrocytes, after ischemia using in vivo and in vitro models. METHODS AND RESULTS Primary astrocytes, ECs, or cocultures were prepared with or without added microglia. Primary ECs were more resistant to oxygen-glucose deprivation/reperfusion than astrocytes. ECs plus astrocytes showed intermediate vulnerability. Microglia added to cocultures nearly doubled cell death. This increase was prevented by minocycline and apocynin. In vivo, minocycline reduced infarct volume and neurological deficits and markedly reduced BBB disruption and hemorrhage in mice after experimental stroke. CONCLUSIONS Inhibition of microglial activation may protect the brain after ischemic stroke by improving BBB viability and integrity. Microglial inhibitors may prove to be an important treatment adjunct to fibrinolysis.
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Affiliation(s)
- Midori A Yenari
- Department of Neurology, University of California, San Francisco Veterans Affairs Medical Center, California 94121, USA.
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Alija AJ, Bresgen N, Sommerburg O, Langhans CD, Siems W, Eckl PM. β-Carotene breakdown products enhance genotoxic effects of oxidative stress in primary rat hepatocytes. Carcinogenesis 2006; 27:1128-33. [PMID: 16418177 DOI: 10.1093/carcin/bgi342] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Since it has to be expected that individuals exposed to oxidative stress who take supplements of beta-carotene are simultaneously exposed to both beta-carotene cleavage products (CPs) and oxidative stress, and both exposures have been demonstrated to cause genotoxic effects in primary rat hepatocytes, cyto- and genotoxic effects on primary rat hepatocytes after supplementation of the medium with increasing concentrations of a CP mixture during exposure to oxidative stress by treatment with either DMNQ (2,3-dimethoxy-1,4-naphthoquinone) or hypoxia/reoxygenation (Hy/Reox) was investigated. The cytological endpoints analysed were the mitotic indices, the percentages of apoptotic and necrotic cells, the percentages of micronucleated (MN) cells and the number of chromosomal aberrations (CAs) and sister chromatid exchanges (SCE). The results obtained clearly demonstrate that the CP mixture enhances the genotoxic effects of oxidative stress exposure, whereas it had no effect at all on the endpoints of cytotoxicity studied. These results further support the hypothesis that CP might be responsible for the reported carcinogenic response in the beta-CArotene and Retinol Efficacy Trial (CARET) and Alpha-Tocopherol Beta-carotene Cancer prevention (ATBC) chemoprevention trials.
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Affiliation(s)
- A J Alija
- Department of Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
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Bresgen N, Jaksch H, Bauer HC, Eckl P, Krizbai I, Tempfer H. Astrocytes are more resistant than cerebral endothelial cells toward geno- and cytotoxicity mediated by short-term oxidative stress. J Neurosci Res 2006; 84:1821-8. [PMID: 16998903 DOI: 10.1002/jnr.21069] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Evidence is accumulating that capillary endothelial cells (cEC) and astrocytes play a pivotal role in neuroprotection, in particular with respect to counteract oxidative injury. Furthermore, differences among both cell types in response to oxidative stress have been shown and astrocytes seem to be more tolerant in terms of cytotoxicity, however, no reports exist on oxidative stress mediated genotoxicity in astrocytes. We investigated genotoxic and cytotoxic effects of oxidative stress in astrocytes and cECs induced by hypoxia/reoxygenation or by the redox cycling quinone DMNQ. Additionally, the dependence of these effects on glucose availabilty was also studied. On exposure to Hy/Re or 10 muM DMNQ for 24 hr, the frequency of micronucleated and apoptotic cells was significantly increasing, however, astrocytes proved to be more resistant to apoptosis induction, in particular on use of DMNQ. In astrocytes, the low background rates of necrotic cells were not affected and a significant necrosis induction was only detectable in cECs exposed to DMNQ for 24 hr. Short-term exposure to DMNQ (1 hr) had no effect in astrocytes but exerted significant geno- and cytotoxicity in cECs. Increasing the glucose concentration markedly reduced oxidative stress mediated geno- and cytotoxicity in astrocytes. Surprisingly, glucose deprivation (aglycemia) suppressed DMNQ induced micronucleus formation in astrocytes without affecting the frequency of apoptotic cells. Our results indicate that astrocytes are more resistant to oxidative stress than cECs, in particular regarding the potential to counteract genotoxicity as well as apoptosis induction mediated by a short term oxidative insult.
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Li J, Ding YH, Rafols JA, Lai Q, McAllister JP, Ding Y. Increased astrocyte proliferation in rats after running exercise. Neurosci Lett 2005; 386:160-4. [PMID: 16024173 DOI: 10.1016/j.neulet.2005.06.009] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 05/27/2005] [Accepted: 06/01/2005] [Indexed: 11/15/2022]
Abstract
The aim in this study was to investigate whether physical exercise could induce astroglial proliferation in the frontoparietal cortex and dorsolateral striatum where extensive angiogenesis had been found after exercise in previous studies. Adult male Sprague Dawley rats (n=48) were used in four experimental groups. Animals were exercised 30 min each day on a treadmill on which repetitive locomotor movement was required, for 0 (n=12), 3 (n=12) or 6 (n=12) weeks, as well as 3-week exercise plus 3-week rest (n=12). Brain tissues of the exercised and non-exercised rats were processed for glial fibrillary acidic protein (GFAP) immunocytochemistry (n=6 x 4) and Western blotting (n=6 x 4) to evaluate regional astrocyte proliferation in the frontoparietal cortex and dorsolateral striatum. By using GFAP immunocytochemistry and stereological methods, we compared the density of astrocytes in the animals with or without exercise. In comparison to non-exercised animals, a significant (p<0.01) increase in the number of astrocytes was observed in both cortex and striatum of rats exercised for 3 or 6 weeks. Our data also indicated that astrocytic density continued to increase up to 6 weeks either with an additional 3 weeks of exercise (p<0.01) or 3 weeks of rest (p<0.01). In addition, Western blotting analysis showed an obvious increase in GFAP protein from cortex and striatum of exercised animals. Astrocytosis after exercise, coupled with angiogenesis, is thought to provide strength to the neurovascular unit (a construct consisting of microvascular endothelium, astroglia, neurons and the extracellular matrix). Strengthening of this unit by exercise may protect blood-brain-barrier function following brain injury, such as that occurring after stroke.
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Affiliation(s)
- Jie Li
- Department of Neurological Surgery, Wayne State University School of Medicine, Canfield, Detroit, MI 48201, USA
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31
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Boveri M, Berezowski V, Price A, Slupek S, Lenfant AM, Benaud C, Hartung T, Cecchelli R, Prieto P, Dehouck MP. Induction of blood-brain barrier properties in cultured brain capillary endothelial cells: comparison between primary glial cells and C6 cell line. Glia 2005; 51:187-98. [PMID: 15800928 DOI: 10.1002/glia.20189] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The communication between glial cells and brain capillary endothelial cells is crucial for a well-differentiated blood-brain barrier (BBB). It has been suggested that in vitro primary glial cells (GCs) be replaced by the glial C6 cell line to standardise the model further. This study compares directly the structural and functional differentiation of bovine brain capillary endothelial cells (BBCECs) induced by co-culture with rat primary GCs or C6 cells, for the first time. Trans-endothelial electrical resistance (TEER) measurements showed that under no condition were C6 cells able to reproduce TEER values as high as in the presence of GCs. At the same time, permeability of the BBCECs to both radioactive sucrose and FITC-inulin was 2.5-fold higher when cells were co-cultured with C6 than with GCs. Furthermore, immunocytochemistry studies showed different cell morphology and less developed tight junction pattern of BBCECs co-cultured with C6 toward GCs. Additionally, studies on P-glycoprotein (P-gp) showed much lower P-gp presence and activity in BBCECs co-cultured with C6 than GCs. Both VEGF mRNA expression and protein content were dramatically increased when compared with GCs, suggesting that VEGF could be one of the factors responsible for higher permeability of BBB. Our results clearly indicate that, in the presence of the glial C6 cell line, BBCECs did not differentiate as well as in the co-culture with primary GCs at both structural and functional levels.
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Affiliation(s)
- Monica Boveri
- ECVAM, Institute for Health and Consumer Protection, Joint Research Centre, European Commission, Ispra (VA), Italy
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Hawkins BT, Davis TP. The blood-brain barrier/neurovascular unit in health and disease. Pharmacol Rev 2005; 57:173-85. [PMID: 15914466 DOI: 10.1124/pr.57.2.4] [Citation(s) in RCA: 1818] [Impact Index Per Article: 95.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The blood-brain barrier (BBB) is the regulated interface between the peripheral circulation and the central nervous system (CNS). Although originally observed by Paul Ehrlich in 1885, the nature of the BBB was debated well into the 20th century. The anatomical substrate of the BBB is the cerebral microvascular endothelium, which, together with astrocytes, pericytes, neurons, and the extracellular matrix, constitute a "neurovascular unit" that is essential for the health and function of the CNS. Tight junctions (TJ) between endothelial cells of the BBB restrict paracellular diffusion of water-soluble substances from blood to brain. The TJ is an intricate complex of transmembrane (junctional adhesion molecule-1, occludin, and claudins) and cytoplasmic (zonula occludens-1 and -2, cingulin, AF-6, and 7H6) proteins linked to the actin cytoskeleton. The expression and subcellular localization of TJ proteins are modulated by several intrinsic signaling pathways, including those involving calcium, phosphorylation, and G-proteins. Disruption of BBB TJ by disease or drugs can lead to impaired BBB function and thus compromise the CNS. Therefore, understanding how BBB TJ might be affected by various factors holds significant promise for the prevention and treatment of neurological diseases.
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Affiliation(s)
- Brian T Hawkins
- Department of Medical Pharmacology, University of Arizona College of Medicine, Tucson, Arizona, USA
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Deli MA, Abrahám CS, Kataoka Y, Niwa M. Permeability studies on in vitro blood-brain barrier models: physiology, pathology, and pharmacology. Cell Mol Neurobiol 2005; 25:59-127. [PMID: 15962509 DOI: 10.1007/s10571-004-1377-8] [Citation(s) in RCA: 472] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
(1) The specifically regulated restrictive permeability barrier to cells and molecules is the most important feature of the blood-brain barrier (BBB). The aim of this review was to summarize permeability data obtained on in vitro BBB models by measurement of transendothelial electrical resistance and by calculation of permeability coefficients for paracellular or transendothelial tracers. (2) Results from primary cultures of cerebral microvascular endothelial cells or immortalized cell lines from bovine, human, porcine, and rodent origin are presented. Effects of coculture with astroglia, neurons, mesenchymal cells, blood cells, and conditioned media, as well as physiological influence of serum components, hormones, growth factors, lipids, and lipoproteins on the barrier function are discussed. (3) BBB permeability results gained on in vitro models of pathological conditions including hypoxia and reoxygenation, neurodegenerative diseases, or bacterial and viral infections have been reviewed. Effects of cytokines, vasoactive mediators, and other pathogenic factors on barrier integrity are also detailed. (4) Pharmacological treatments modulating intracellular cyclic nucleotide or calcium levels, and activity of protein kinases, protein tyrosine phosphatases, phospholipases, cyclooxygenases, or lipoxygenases able to change BBB integrity are outlined. Barrier regulation by drugs involved in the metabolism of nitric oxide and reactive oxygen species, as well as influence of miscellaneous treatments are also listed and evaluated. (5) Though recent advances resulted in development of improved in vitro BBB model systems to investigate disease modeling, drug screening, and testing vectors targeting the brain, there is a need for checking validity of permeability models and cautious interpretation of data.
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Affiliation(s)
- Máiria A Deli
- Laboratory of Molecular Neurobiology, Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Temesvári körút 62, H-6726 Szeged, Hungary.
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Hayashi K, Nakao S, Nakaoke R, Nakagawa S, Kitagawa N, Niwa M. Effects of hypoxia on endothelial/pericytic co-culture model of the blood-brain barrier. ACTA ACUST UNITED AC 2005; 123:77-83. [PMID: 15518896 DOI: 10.1016/j.regpep.2004.05.023] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The blood-brain barrier (BBB) is composed of endothelial cells, pericytes and astrocytic foot processes. Most research for the in vitro BBB is performed endothelial cells with or without astrocytes. Hypoxia damage to the BBB induces vasogenic brain edema. We have generated a new model of the BBB with brain endothelial cells and pericytes and have examined the effects of hypoxia using this model. Brain microvascular endothelial cells and pericytes were isolated from three-week-old male Wister rats using enzyme and mechanical homogenization. Three models (A: only endothelial monolayer, B: endothelial monolayer with pericytes non-contact condition, and C: contact condition) were made by culturing these cells using Transwell co-culture system and were exposed to hypoxic condition. We evaluated barrier function with transendothelial electrical resistance (TEER) and permeability of Evans blue-albumin and sodium fluorescein. The tightest barrier was observed in the endothelial/pericytic contact model. Despite hypoxia-induced disruption of the barrier in endothelial monolayer and non-contact co-culture models, a minimum of dysfunction was seen in the contact co-culture model. Therefore, it is considered that pericytes effect on the endothelia by secreting factors or through a gap junction. In short, pericytes induce endothelial maturation and a tighter barrier function, which supports the function against the hypoxic injury. Intercellular communication might be important to keep the BBB functional and stabilize in hypoxia.
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Affiliation(s)
- Kentaro Hayashi
- Department of Neurosurgery, Nagasaki University School of Medicine, Nagasaki, Japan.
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Parran DK, Magnin G, Li W, Jortner BS, Ehrich M. Chlorpyrifos Alters Functional Integrity and Structure of an In Vitro BBB Model: Co-cultures of Bovine Endothelial Cells and Neonatal Rat Astrocytes. Neurotoxicology 2005; 26:77-88. [PMID: 15527875 DOI: 10.1016/j.neuro.2004.07.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Accepted: 07/09/2004] [Indexed: 11/15/2022]
Abstract
The blood-brain barrier (BBB) is a structural and functional interface between the circulatory system and the brain. Organophosphorous compounds such as chlorpyrifos (CPF) may cross the BBB and disrupt BBB integrity and function. To determine events that may contribute to CPF toxicity, we used an in vitro BBB model in which bovine microvascular endothelial cells (BMEC) and neonatal rat astrocytes were co-cultured. We hypothesized that CPF is metabolized by the BBB leading to an inhibition of esterase activity and a disruption of the BBB. The co-culturing of BMECs and astrocytes resulted in tight junction formation as determined by electron microscopy, electrical resistance and western blot analysis of two tight junction-associated proteins (ZO-1 and e-cadherin). We observed time dependent increases in ZO-1 and e-cadherin expression and electrical resistance during BBB formation, which were maximal after 9-13 days of co-culturing. The CPF concentration and production of its metabolites were monitored by HPLC following 24 h exposure to CPF on the luminal side of the BBB. We found that the BBB metabolized CPF, with the metabolite 2,3,6-trichloro-2-pyridinol being the major product. CPF and its metabolites were detected on the abluminal side of the BBB suggesting that CPF crossed this barrier. CPF was also detected intracellularly and on the membrane inserts. At tested concentrations (0.1-10 microM), CPF inhibited both carboxylesterase (CaE) and cholinesterase (ChE) activities in BMECs by 43-100%, while CPF-oxon totally inhibited CaE and ChE activity in concentrations as low as 0.1 microM. CPF also caused a concentration-dependent decrease in electrical resistance, with significant inhibition observed at 1 nM and complete loss at 1 microM. These data show that low concentrations of CPF and its metabolites are present within the BBB. CPF and its metabolites, especially CPF-oxon, contribute to the inhibition of CaE and ChE activity, as well as the alteration of BBB integrity and structure.
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Affiliation(s)
- Damani K Parran
- Laboratory for Neurotoxicity Studies, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, 1 Duckpond Drive, Blacksburg, VA 24061-0442, USA
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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: 1500] [Impact Index Per Article: 75.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2003] [Revised: 11/21/2003] [Accepted: 12/10/2003] [Indexed: 02/08/2023] Open
Abstract
The blood-brain barrier (BBB) is a diffusion barrier, which impedes influx of most compounds from blood to brain. Three cellular elements of the brain microvasculature compose the BBB-endothelial cells, astrocyte end-feet, and pericytes (PCs). Tight junctions (TJs), present between the cerebral endothelial cells, form a diffusion barrier, which selectively excludes most blood-borne substances from entering the brain. Astrocytic end-feet tightly ensheath the vessel wall and appear to be critical for the induction and maintenance of the TJ barrier, but astrocytes are not believed to have a barrier function in the mammalian brain. Dysfunction of the BBB, for example, impairment of the TJ seal, complicates a number of neurologic diseases including stroke and neuroinflammatory disorders. We review here the recent developments in our understanding of the BBB and the role of the BBB dysfunction in CNS disease. We have focused on intraventricular hemorrhage (IVH) in premature infants, which may involve dysfunction of the TJ seal as well as immaturity of the BBB in the germinal matrix (GM). A paucity of TJs or PCs, coupled with incomplete coverage of blood vessels by astrocyte end-feet, may account for the fragility of blood vessels in the GM of premature infants. Finally, this review describes the pathogenesis of increased BBB permeability in hypoxia-ischemia and inflammatory mechanisms involving the BBB in septic encephalopathy, HIV-induced dementia, multiple sclerosis, and Alzheimer disease.
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Affiliation(s)
- Praveen Ballabh
- Department of Pediatrics, New York Medical College and Westchester Medical Center, Valhalla, NY 10595, USA.
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Abstract
Atherosclerosis is a disease of the large arteries that involves a characteristic accumulation of high-molecular-weight lipoprotein in the arterial wall. This review focuses on the mass transport processes that mediate the focal accumulation of lipid in arteries and places particular emphasis on the role of fluid mechanical forces in modulating mass transport phenomena. In the final analysis, four mass transport mechanisms emerge that may be important in the localization of atherosclerosis: blood phase controlled hypoxia, leaky endothelial junctions, transient intercellular junction remodeling, and convective clearance of the subendothelial intima and media. Further study of these mechanisms may contribute to the development of therapeutic strategies for atherosclerotic diseases.
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Affiliation(s)
- John M Tarbell
- The City College of New York/CUNY, New York, New York 10031, USA.
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Brown RC, Mark KS, Egleton RD, Huber JD, Burroughs AR, Davis TP. Protection against hypoxia-induced increase in blood-brain barrier permeability: role of tight junction proteins and NFkappaB. J Cell Sci 2003; 116:693-700. [PMID: 12538770 DOI: 10.1242/jcs.00264] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Co-culture with glial cells and glia-conditioned media can induce blood-brain barrier properties in microvessel endothelial cells and protect against hypoxia-induced blood-brain barrier breakdown. We examined the effect of two types of glia-conditioned media on brain microvessel endothelial cell permeability and tight junction protein expression, and studied potential mechanisms of action. We found that C6-glioma-conditioned media, but not rat astrocyte-conditioned media, protected against an increase in permeability induced by exposure to 1% oxygen for 24 hours. This hypoxic stress caused an increase in the expression of tight junction proteins claudin-1 and actin, particularly in cells treated with C6-conditioned media. We found that C6-conditioned media has a significantly higher level of both basic fibroblast growth factor and vascular endothelial growth factor. Treatment with C6-conditioned media for 1 or 3 days protects against hypoxia-induced permeability increases, and this protective effect may be mediated by signal transduction pathways terminating at the transcription factor NFkappaB.
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Affiliation(s)
- Rachel C Brown
- Department of Pharmacology, The University of Arizona College of Medicine, Tucson, AZ, USA
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Petty MA, Lo EH. Junctional complexes of the blood-brain barrier: permeability changes in neuroinflammation. Prog Neurobiol 2002; 68:311-23. [PMID: 12531232 DOI: 10.1016/s0301-0082(02)00128-4] [Citation(s) in RCA: 241] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A wide range of central nervous system (CNS) disorders include neuroinflammatory events that perturb blood-brain barrier (BBB) integrity. Mechanisms by which the BBB responds to physiological and pathological stimuli involve signaling systems in the tight and adherens junctions of the cerebral endothelium. In this review, we examine the molecular composition and regulatory mediators that control BBB permeability and assess how these mediators may be dysregulated in stroke, multiple sclerosis, brain tumors, and meningioencephalitis. An understanding of these molecular substrates in BBB regulation may lead to new approaches for enhancing CNS drug delivery and ameliorating brain edema after injury and inflammation.
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Affiliation(s)
- Margaret A Petty
- CNS Pharmacology, Aventis Pharmaceuticals Inc., Route 202-206, P.O. Box 6800, Bridgewater, NJ 08807, USA.
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Huber JD, Egleton RD, Davis TP. Molecular physiology and pathophysiology of tight junctions in the blood-brain barrier. Trends Neurosci 2001; 24:719-25. [PMID: 11718877 DOI: 10.1016/s0166-2236(00)02004-x] [Citation(s) in RCA: 557] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Disruption of the tight junctions (TJs) of the blood-brain barrier (BBB) is a hallmark of many CNS pathologies, including stroke, HIV encephalitis, Alzheimer's disease, multiple sclerosis and bacterial meningitis. Furthermore, systemic-derived inflammation has recently been shown to cause BBB tight junctional disruption and increased paracellular permeability. The BBB is capable of rapid modulation in response to physiological stimuli at the cytoskeletal level, which enables it to protect the brain parenchyma and maintain a homeostatic environment. By allowing the "loosening" of TJs and an increase in paracellular permeability, the BBB is able to "bend without breaking"; thereby, maintaining structural integrity.
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Affiliation(s)
- J D Huber
- Department of Pharmacology, The University of Arizona College of Medicine, Tucson, AZ 85724, USA
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Gaillard PJ, Voorwinden LH, Nielsen JL, Ivanov A, Atsumi R, Engman H, Ringbom C, de Boer AG, Breimer DD. Establishment and functional characterization of an in vitro model of the blood-brain barrier, comprising a co-culture of brain capillary endothelial cells and astrocytes. Eur J Pharm Sci 2001; 12:215-22. [PMID: 11113640 DOI: 10.1016/s0928-0987(00)00123-8] [Citation(s) in RCA: 251] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim was to establish a flexible, abundantly available, reproducible and functionally characterized in vitro model of the blood-brain barrier (BBB). METHODS In a first step, bovine brain capillaries and newborn rat astrocytes were isolated. Subsequently, a co-culture of primary brain capillary endothelial cells (BCEC) on semi-permeable filter inserts, with astrocytes on the bottom of the filter was established. The cell material was characterized on the basis of specific cell-type properties and (functional expression of) specific BBB properties. RESULTS BCEC displayed: (1) characteristic endothelial cell morphology; (2) expression of endothelial cell markers (i.e., CD51, CD62P, CD71 and cadherin 5); (3) marginal F-actin localization; (4) tight junction formation between the cells; (5) expression of gamma-glutamyl-transpeptidase (gamma-GTP); (6) expression of P-glycoprotein (Pgp); (7) functional transendothelial transferrin transport and uptake; (8) restriction of paracellular transport; and (9) high transendothelial electrical resistance (TEER). Astrocytes displayed characteristic astrocyte morphology and expressed glial fibrillary acidic protein (GFAP). Co-culture with astrocytes increased TEER and decreased paracellular transport. In addition, expression of the glucocorticoid receptor (GR) was demonstrated in the endothelial cells of the BBB, while no expression of the mineralocorticoid receptor (MR) was found. CONCLUSIONS A high quality and mass-production in vitro BBB model was established in which experiments with physiological (e.g., regulation of BBB permeability), pharmacological (e.g., pharmacokinetics and pharmacodynamics) and pathophysiological (e.g., disease influence on BBB permeability) objectives can be reproducibly performed.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/biosynthesis
- Algorithms
- Animals
- Animals, Newborn
- Astrocytes/metabolism
- Astrocytes/ultrastructure
- Blood-Brain Barrier/drug effects
- Blood-Brain Barrier/physiology
- Brain/cytology
- Brain/ultrastructure
- Capillaries/cytology
- Capillaries/metabolism
- Capillaries/ultrastructure
- Cattle
- Cells, Cultured
- Cerebrovascular Circulation/physiology
- Coculture Techniques
- Endothelium, Vascular/cytology
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/ultrastructure
- Humans
- Infant, Newborn
- Microscopy, Electron
- Models, Biological
- Rats
- Rats, Wistar
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Affiliation(s)
- P J Gaillard
- Department of Pharmacology, Leiden/Amsterdam Center for Drug Research (LACDR), Leiden University, P.O. Box 9503, 2300 RA, Leiden, The Netherlands
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Dohgu S, Kataoka Y, Ikesue H, Naito M, Tsuruo T, Oishi R, Sawada Y. Involvement of glial cells in cyclosporine-increased permeability of brain endothelial cells. Cell Mol Neurobiol 2000; 20:781-6. [PMID: 11100984 DOI: 10.1023/a:1007015228318] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. To test whether astrocytes participate in cyclosporine-induced dysfunction of the blood-brain barrier, we examined the effects of cyclosporine on the permeability of the mouse brain endothelial (MBEC4) cells cocultured with C6 glioma cells, each cell layer placed on the top and bottom of the insert membrane, respectively. 2. The presence of C6 cells remarkably aggravated cyclosporine-increased permeability of MBEC4 cells to sodium fluorescein. 3. In light of these findings, the possibility that astroglial cells could contribute to the occurrence of cyclosporine-induced dysfunction of the blood-brain barrier triggering neurotoxicity should be considered.
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Affiliation(s)
- S Dohgu
- Department of Hospital Pharmacy, Faculty of Medicine, Kyushu University Fukuoka, Japan
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Fischer S, Wobben M, Kleinstück J, Renz D, Schaper W. Effect of astroglial cells on hypoxia-induced permeability in PBMEC cells. Am J Physiol Cell Physiol 2000; 279:C935-44. [PMID: 11003573 DOI: 10.1152/ajpcell.2000.279.4.c935] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An in vitro model of the blood-brain barrier (BBB), consisting of porcine brain-derived microvascular endothelial cells (PBMEC), was used to evaluate the effect of astrocytes in the BBB disruption during hypoxia. Hypoxia-induced hyperpermeability was decreased significantly in a coculture model of astroglia cells, either astrocytes or C6 glioma cells, with PBMEC and, to the same extent, when glia cell-conditioned medium was used. Corresponding to effects on hypoxia-induced hyperpermeability, astrocyte- and C6 cell-conditioned medium diminished hypoxia-induced vascular endothelial growth factor (VEGF) mRNA and protein expression, which recently was shown to be responsible for hypoxia-induced permeability changes in vitro. The effect on hypoxia-induced hyperpermeability and VEGF expression was specific for astroglia cells because conditioned medium from bovine smooth muscle cells (BSMC) did not show any effect. Immunocytochemistry revealed that 24 h of hypoxia disrupted the continuity of the tight junction protein, zonula occludens-1 (ZO-1), which lines the cytoplasmic face of intact tight junctions. These changes were prevented when hypoxia was performed in glia cell-conditioned medium. Results suggest that astrocytes protect the BBB from hypoxia-induced paracellular permeability changes by decreasing hypoxia-induced VEGF expression in microvascular endothelial cells.
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Affiliation(s)
- S Fischer
- Department of Anesthesiology and Intensive Care, Max-Planck Institute for Physiological and Clinical Research, D-61231 Bad Nauheim, Germany.
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44
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Abstract
The blood-brain barrier (BBB) which is located in the continuous endothelial lining of cerebral blood vessels rigidly controls exchange of water soluble compounds under physiological conditions. Under pathological conditions such as trauma or ischemia, BBB permeability may increase thus allowing plasma constituents to escape into brain tissue. This "opening" of the BBB may, at least in part, be mediated by massive release of autacoids resulting in vasogenic brain edema. Five criteria have to be fulfilled by an individual autacoid to be considered a mediator candidate of cerebral edema: i) a permeability-enhancing action under physiological conditions, ii) a vasodilatory action, iii) the ability to induce vasogenic brain edema, iv) an increase of concentration in the tissue or interstitial fluid under pathological conditions, and v) a decrease of brain edema by specific interference with the release or action of a given autacoid. Among the mediator candidates considered, bradykinin is the only one to meet all criteria. Histamine, arachidonic acid and free radicals including nitric oxide may also be considered mediators of brain edema, but for each of these compounds evidence is less clear than for bradykinin. Although the concept of mediators inducing brain edema is well established by experimental studies, only a bradykinin receptor antagonist has so far gained entrance into clinical evaluation.
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Affiliation(s)
- L Schilling
- Dept. Neurosurg., Fac. Clin. Med., Mannheim, Univ. Heidelberg, Germany
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45
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Schroeter ML, Mertsch K, Giese H, Müller S, Sporbert A, Hickel B, Blasig IE. Astrocytes enhance radical defence in capillary endothelial cells constituting the blood-brain barrier. FEBS Lett 1999; 449:241-4. [PMID: 10338140 DOI: 10.1016/s0014-5793(99)00451-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Astrocytes (AC) induce blood-brain barrier (BBB) properties in brain endothelial cells (EC). As antioxidative activity (AOA) is assumed to be a BBB characteristic, we tested whether AC improve AOA of EC. Monocultivated AC showed higher AOA [manganese superoxide dismutase (SOD), catalase (Cat), glutathione peroxidase (GPx)] than EC. Cocultivation elevated AOA in EC (MnSOD, CuZnSOD, Cat, GPx), and AC (MnSOD, CuZnSOD, GPx). Hypoxia increased radical-induced membrane lipid peroxidation in monocultivated, but not in cocultivated EC. Thus, EC/AC cocultivation intensifies AOA in both cell types, protects the EC, and therefore, the BBB against oxidative stress. The high AOA is regarded as an essential property of the BBB, which is induced by AC.
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Affiliation(s)
- M L Schroeter
- Forschungsinstitut für Molekulare Pharmakologie, Berlin, Germany
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46
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Kawase M, Kinouchi H, Kato I, Akabane A, Kondo T, Arai S, Fujimura M, Okamoto H, Yoshimoto T. Inducible nitric oxide synthase following hypoxia in rat cultured glial cells. Brain Res 1996; 738:319-22. [PMID: 8955528 DOI: 10.1016/s0006-8993(96)00924-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Nitric oxide (NO) produced by inducible nitric oxide (iNOS) exerts inhibitory and cytotoxic effects on various cells including neuronal cells. In the present study, we examined the ability of rat glial cells to produce NO following hypoxia/reoxygenation in vitro by measuring nitrite. The levels of nitrite produced in the cultured media of glial cells significantly increased after 12-h hypoxia but not after 0- and 6-h hypoxia. The NOS inhibitor, NG-monomethyl-L-arginine, decreased hypoxia-induced nitrite formation. In glial cells after hypoxia/reoxygenation, the iNOS and mRNA and protein expressions were detected by reverse-transcription polymerase chain reaction and by immunocytochemical analysis, respectively. The present study provides the first evidence that hypoxia induces NO production from glial cells. This hypoxia-induced, glial cell-derived NO may play a critical role in the pathogenesis of cerebral ischemia in vivo.
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Affiliation(s)
- M Kawase
- Department of Neurosurgery, Tohoku University, School of Medicine, Sendai, Japan
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47
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Kondo T, Kinouchi H, Kawase M, Yoshimoto T. Differential response in the release of hydrogen peroxide between astroglial cells and endothelial cells following hypoxia/reoxygenation. Neurosci Lett 1996. [DOI: 10.1016/0304-3940(96)12954-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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