Permeability of Endothelial and Astrocyte Cocultures: In Vitro Blood–Brain Barrier Models for Drug Delivery Studies

Li, Guanglei; Simon, Melissa J.; Cancel, Limary M.; Shi, Zhong‐Dong; Ji, Xin‐Ying; Tarbell, John M.; Morrison, Barclay; Fu, Bingmei M.

doi:10.1007/s10439-010-0023-5

Cited by 208 publications

(180 citation statements)

References 51 publications

(64 reference statements)

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“…For some experiments, the permeability of hBMVECs monolayers was also evaluated by phenol red diffusion assay. M199 growth medium in the lower chamber was replaced by a similar medium without phenol red (1000 l) and incubated for 2 h. The diffusion of phenol red across the monolayer was determined by measuring absorbance at 546 nm (56). Indirect immunofluorescence imaging of the tight junction marker ZO1 (Life Technologies) was also used to measure tight junction integrity as described below.…”

Section: Methodsmentioning

confidence: 99%

Na+/H+ Exchanger 9 Regulates Iron Mobilization at the Blood-Brain Barrier in Response to Iron Starvation

Beydoun¹,

Hamood²,

Zubieta

et al. 2017

Journal of Biological Chemistry

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Edited by Paul E. FraserIron is essential for brain function, with loss of iron homeostasis in the brain linked to neurological diseases ranging from rare syndromes to more common disorders, such as Parkinson's and Alzheimer's diseases. Iron entry into the brain is regulated by the blood-brain barrier (BBB). Molecular mechanisms regulating this transport are poorly understood. Using an in vitro model of the BBB, we identify NHE9, an endosomal cation/proton exchanger, as a novel regulator of this system. Human brain microvascular endothelial cells (hBMVECs) that constitute the BBB receive brain iron status information via paracrine signals from ensheathing astrocytes. In hBMVECs, we show that NHE9 expression is up-regulated very early in a physiological response invoked by paracrine signals from iron-starved astrocytes. Ectopic expression of NHE9 in hBMVECs without external cues induced up-regulation of the transferrin receptor (TfR) and down-regulation of ferritin, leading to an increase in iron uptake. Mechanistically, we demonstrate that NHE9 localizes to recycling endosomes in hBMVECs where it raises the endosomal pH. The ensuing alkalization of the endosomal lumen increased translocation of TfRs to the hBMVEC membrane. TfRs on the membrane were previously shown to facilitate both recycling-dependent and -independent iron uptake. We propose that NHE9 regulates TfR-dependent, recycling-independent iron uptake in hBMVECs by fine-tuning the endosomal pH in response to paracrine signals and is therefore an important regulator in iron mobilization pathway at the BBB.There is high demand for iron in the brain, one of the most metabolically active organs in the body (1, 2). Iron is a co-factor of several proteins involved in specialized brain cell functions such as synthesis of neurotransmitters and myelination (3-5). Iron is also necessary for housekeeping functions such as mitochondrial respiration and DNA synthesis, crucial for brain function (5). Insufficient or surplus iron in the brain has been associated with various neurological diseases (6 -10). Although iron deficiency is associated with cognitive and brain structural deficits, excess brain iron is implicated in Alzheimer's, Parkinson's, and other neurodegenerative diseases (10, 11). Therefore, it is not surprising that iron levels are tightly regulated in the brain (10).Iron entry into the brain is regulated by the blood-brain barrier (BBB) 3 (10). This physiological barrier is characterized by tight junctions between brain microvascular endothelial cells (BMVECs) that block passive diffusion of iron into the brain (12). BMVECs are polarized cells with one surface (apical) facing the blood and the other (basal or abluminal) facing interstitial fluid of the brain. BMVECs and ensheathing astrocytes form the regulatory axis of the BBB, modulating iron transport from blood into the brain interstitium (2, 13). It is now known that BMVECs are the focal point for regulation of cerebral iron homeostasis and not mere conduits for iron transport (14). Paracrine fac...

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Section: Methodsmentioning

confidence: 99%

Na+/H+ Exchanger 9 Regulates Iron Mobilization at the Blood-Brain Barrier in Response to Iron Starvation

Beydoun¹,

Hamood²,

Zubieta

et al. 2017

Journal of Biological Chemistry

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“…The resulting permeability coefficients for FDX-70,000 in an intact bEnd.3 cells monolayer (Table 1) are consistent with literature reports. 22 Treatment of the monolayers with either AmS-IONPs or EDT-IONPs (50 μg/mL) had no effect on the magnitude of FDX-70,000 permeability, suggesting that neither of the nanoparticle preparations compromised monolayer integrity (Figure 2A and C; Table 1). In the intact cell monolayers, the permeability of AmS-IONPs was minimal, with less than 1% of the AmS-IONPs in the basolateral compartment after 24 hours ( Figure 2B).…”

Section: Permeability Studies Of Ams-ionps and Edt-ionpsmentioning

confidence: 98%

Magnetic field enhanced convective diffusion of iron oxide nanoparticles in an osmotically disrupted cell culture model of the blood–brain barrier

Sun¹,

Worden²,

Wroczynskyj³

et al. 2014

IJN

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Purpose The present study examines the use of an external magnetic field in combination with the disruption of tight junctions to enhance the permeability of iron oxide nanoparticles (IONPs) across an in vitro model of the blood–brain barrier (BBB). The feasibility of such an approach, termed magnetic field enhanced convective diffusion (MFECD), along with the effect of IONP surface charge on permeability, was examined. Methods The effect of magnetic field on the permeability of positively (aminosilane-coated [AmS]-IONPs) and negatively (N-(trimethoxysilylpropyl)ethylenediaminetriacetate [EDT]-IONPs) charged IONPs was evaluated in confluent monolayers of mouse brain endothelial cells under normal and osmotically disrupted conditions. Results Neither IONP formulation was permeable across an intact cell monolayer. However, when tight junctions were disrupted using D-mannitol, flux of EDT-IONPs across the bEnd.3 monolayers was 28%, increasing to 44% when a magnetic field was present. In contrast, the permeability of AmS-IONPs after osmotic disruption was less than 5%. The cellular uptake profile of both IONPs was not altered by the presence of mannitol. Conclusions MFECD improved the permeability of EDT-IONPs through the paracellular route. The MFECD approach favors negatively charged IONPs that have low affinity for the brain endothelial cells and high colloidal stability. This suggests that MFECD may improve IONP-based drug delivery to the brain.

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“…5B). The endothelial cells of the capillaries in CNS form tight junctions with low permeability, which contributes to the protective function of BBB (29). The integrity of the tight junction directly determines the permeability of BBB (30).…”

Section: Montelukast Alleviates Ltd 4 -Induced Bbb Disruptionmentioning

confidence: 99%

Antiasthmatic Drugs Targeting the Cysteinyl Leukotriene Receptor 1 Alleviate Central Nervous System Inflammatory Cell Infiltration and Pathogenesis of Experimental Autoimmune Encephalomyelitis

Wang

et al. 2011

The Journal of Immunology

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Cysteinyl leukotrienes (CysLTs) are potent proinflammatory mediators and are considered to play a key role in inflammatory diseases such as asthma. Antagonists targeting the receptor of CysLTs (CysLT1) are currently used as antiasthmatic drugs. CysLTs have also been implicated in other inflammatory reactions. In this study, we report that in experimental autoimmune encephalomyelitis animals, CysLT1 is upregulated in immune tissue and the spinal cord, and CysLT levels in the blood and cerebrospinal fluid are also higher than in normal mice. Two clinically used antiasthma drugs, montelukast and zafirlukast, both targeting CysLT1, effectively block the CNS infiltration of inflammatory cells and thus reduce the incidence, peak severity, and cumulative clinical scores. Further study indicated that CysLT1 signaling does not affect the differentiation of pathogenic T helper cells. It might affect the pathogenesis of experimental autoimmune encephalomyelitis by increasing the secretion of IL-17 from myelin oligodendrocyte glycoprotein-specific T cells, increasing the permeability of the blood–brain barrier and inducing chemotaxis of T cells. These effects can be blocked by CysLT1 antagonists. Our findings indicate that the antiasthmatic drugs against CysLT1 can also be used to treat multiple sclerosis.

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Permeability of Endothelial and Astrocyte Cocultures: In Vitro Blood–Brain Barrier Models for Drug Delivery Studies

Cited by 208 publications

References 51 publications

Na+/H+ Exchanger 9 Regulates Iron Mobilization at the Blood-Brain Barrier in Response to Iron Starvation

Na+/H+ Exchanger 9 Regulates Iron Mobilization at the Blood-Brain Barrier in Response to Iron Starvation

Magnetic field enhanced convective diffusion of iron oxide nanoparticles in an osmotically disrupted cell culture model of the blood–brain barrier

Antiasthmatic Drugs Targeting the Cysteinyl Leukotriene Receptor 1 Alleviate Central Nervous System Inflammatory Cell Infiltration and Pathogenesis of Experimental Autoimmune Encephalomyelitis

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Permeability of Endothelial and Astrocyte Cocultures: In Vitro Blood–Brain Barrier Models for Drug Delivery Studies

Cited by 208 publications

References 51 publications

Na+/H+ Exchanger 9 Regulates Iron Mobilization at the Blood-Brain Barrier in Response to Iron Starvation

Na+/H+ Exchanger 9 Regulates Iron Mobilization at the Blood-Brain Barrier in Response to Iron Starvation

Magnetic field enhanced convective diffusion of iron oxide nanoparticles in an osmotically disrupted cell culture model of the blood&ndash;brain barrier

Antiasthmatic Drugs Targeting the Cysteinyl Leukotriene Receptor 1 Alleviate Central Nervous System Inflammatory Cell Infiltration and Pathogenesis of Experimental Autoimmune Encephalomyelitis

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Magnetic field enhanced convective diffusion of iron oxide nanoparticles in an osmotically disrupted cell culture model of the blood–brain barrier