Microembolus clearance through angiophagy is an auxiliary mechanism preserving tissue perfusion in the rat brain

AbstractConsidering its intolerance to ischemia, it is of critical importance for the brain to efficiently process microvascular occlusions and maintain tissue perfusion. In addition to collateral microvascular flow and enzymatic degradation of emboli, the endothelium has the potential to engulf microparticles and thereby recanalize the vessel, through a process called angiophagy. Here, we set out to study the dynamics of angiophagy in relation to cytoskeletal remodeling in vitro and reperfusion in vivo. We show that polystyrene microspheres and fibrin clots are actively taken up by (brain) endothelial cells in vitro, and chart the dynamics of the actin cytoskeleton during this process using live cell imaging. Whereas microspheres were taken up through the formation of a cup structure by the apical endothelial membrane, fibrin clots were completely engulfed by the cells, marked by dense F-actin accumulation surrounding the clot. Both microspheres and fibrin clots were retained in the endothelial cells. Notably, fibrin clots were not degraded intracellularly. Using an in vivo microembolization rat model, in which microparticles are injected into the common carotid artery, we found that microspheres are transported by the endothelium from the microvasculature into the brain parenchyma. Microembolization with microspheres caused temporal opening of the blood–brain barrier and vascular nonperfusion, followed by microsphere extravasation and restoration of vessel perfusion over time. Taken together, angiophagy is accompanied by active cytoskeletal remodeling of the endothelium, and is an effective mechanism to restore perfusion of the occluded microvasculature in vivo.

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Vascular Dysfunction Induced by Mercury Exposure

International Journal of Molecular Sciences ◽

10.3390/ijms20102435 ◽

2019 ◽

Vol 20 (10) ◽

pp. 2435 ◽

Cited By ~ 4

Author(s):

Tetsuya Takahashi ◽

Takayoshi Shimohata

Keyword(s):

Oxidative Stress ◽

Vascular Dysfunction ◽

Brain Parenchyma ◽

Transport Systems ◽

Mehg Exposure ◽

In Vivo Models ◽

The Central Nervous System ◽

The Brain

Methylmercury (MeHg) causes severe damage to the central nervous system, and there is increasing evidence of the association between MeHg exposure and vascular dysfunction, hemorrhage, and edema in the brain, but not in other organs of patients with acute MeHg intoxication. These observations suggest that MeHg possibly causes blood–brain barrier (BBB) damage. MeHg penetrates the BBB into the brain parenchyma via active transport systems, mainly the l-type amino acid transporter 1, on endothelial cell membranes. Recently, exposure to mercury has significantly increased. Numerous reports suggest that long-term low-level MeHg exposure can impair endothelial function and increase the risks of cardiovascular disease. The most widely reported mechanism of MeHg toxicity is oxidative stress and related pathways, such as neuroinflammation. BBB dysfunction has been suggested by both in vitro and in vivo models of MeHg intoxication. Therapy targeted at both maintaining the BBB and suppressing oxidative stress may represent a promising therapeutic strategy for MeHg intoxication. This paper reviews studies on the relationship between MeHg exposure and vascular dysfunction, with a special emphasis on the BBB.

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The CCL2-CCR2 astrocyte-cancer cell axis in tumor extravasation at the brain

Science Advances ◽

10.1126/sciadv.abg8139 ◽

2021 ◽

Vol 7 (26) ◽

pp. eabg8139

Author(s):

Cynthia Hajal ◽

Yoojin Shin ◽

Leanne Li ◽

Jean Carlos Serrano ◽

Tyler Jacks ◽

...

Keyword(s):

Cancer Cells ◽

Cancer Cell ◽

Three Dimensional ◽

Brain Parenchyma ◽

Cell Axis ◽

Chemokine Ligand ◽

Chemokine Ligand 2 ◽

The Brain

Although brain metastases are common in cancer patients, little is known about the mechanisms of cancer extravasation across the blood-brain barrier (BBB), a key step in the metastatic cascade that regulates the entry of cancer cells into the brain parenchyma. Here, we show, in a three-dimensional in vitro BBB microvascular model, that astrocytes promote cancer cell transmigration via their secretion of C-C motif chemokine ligand 2 (CCL2). We found that this chemokine, produced primarily by astrocytes, promoted the chemotaxis and chemokinesis of cancer cells via their C-C chemokine receptor type 2 (CCR2), with no notable changes in vascular permeability. These findings were validated in vivo, where CCR2-deficient cancer cells exhibited significantly reduced rates of arrest and transmigration in mouse brain capillaries. Our results reveal that the CCL2-CCR2 astrocyte-cancer cell axis plays a fundamental role in extravasation and, consequently, metastasis to the brain.

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Isolation and in vitro culture of primary pia mater cells

10.1101/2021.02.01.429222 ◽

2021 ◽

Author(s):

Fadi Saadeh ◽

Jan Remsik ◽

Camille Derderian ◽

Yudan Chi ◽

Adrienne Boire

Keyword(s):

Brain Parenchyma ◽

Pia Mater ◽

Cell Functions ◽

Flow Cytometric ◽

Health And Disease ◽

Unexplored Area ◽

The Brain ◽

Marker Identification

AbstractThe meninges remain an unexplored area of neurobiology. These structures play host to dozens of morbid pathologies. This protocol provides a reliable way to identify and isolate pial cells from mice using robust markers of pial identity in mouse and human tissues. We describe a protocol for the extraction of pia mater cells from mice and their culture as primary cells in vitro. Using an array of transcriptomic, histological, and flow cytometric analyses, we identified Icam1 and Slc38a2 as two novel pia mater markers in vitro and in vivo. Our results confirm the fibroblastoid nature of pial cells and their ability to form a sheet-like layer that covers the brain parenchyma. To our knowledge, this is the first published protocol for the isolation, tissue culture, and marker identification of pial cells from mice. These findings will enable researchers in CNS barriers to describe pial cell functions in both health and disease.

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Increased brain uptake of targeted nanoparticles by adding an acid-cleavable linkage between transferrin and the nanoparticle core

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1517048112 ◽

2015 ◽

Vol 112 (40) ◽

pp. 12486-12491 ◽

Cited By ~ 116

Author(s):

Andrew J. Clark ◽

Mark E. Davis

Keyword(s):

Brain Parenchyma ◽

Common Mechanism ◽

High Avidity ◽

Brain Uptake ◽

Targeted Nanoparticles ◽

High Affinity ◽

The Brain ◽

Nanoparticle Core

Most therapeutic agents are excluded from entering the central nervous system by the blood–brain barrier (BBB). Receptor mediated transcytosis (RMT) is a common mechanism used by proteins, including transferrin (Tf), to traverse the BBB. Here, we prepared Tf-containing, 80-nm gold nanoparticles with an acid-cleavable linkage between the Tf and the nanoparticle core to facilitate nanoparticle RMT across the BBB. These nanoparticles are designed to bind to Tf receptors (TfRs) with high avidity on the blood side of the BBB, but separate from their multidentate Tf–TfR interactions upon acidification during the transcytosis process to allow release of the nanoparticle into the brain. These targeted nanoparticles show increased ability to cross an in vitro model of the BBB and, most important, enter the brain parenchyma of mice in greater amounts in vivo after systemic administration compared with similar high-avidity nanoparticles containing noncleavable Tf. In addition, we investigated this design with nanoparticles containing high-affinity antibodies (Abs) to TfR. With the Abs, the addition of the acid-cleavable linkage provided no improvement to in vivo brain uptake for Ab-containing nanoparticles, and overall brain uptake was decreased for all Ab-containing nanoparticles compared with Tf-containing ones. These results are consistent with recent reports of high-affinity anti-TfR Abs trafficking to the lysosome within BBB endothelium. In contrast, high-avidity, Tf-containing nanoparticles with the acid-cleavable linkage avoid major endothelium retention by shedding surface Tf during their transcytosis.

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Leukocyte Recruitment in the Cerebrospinal Fluid of Mice with Experimental Meningitis Is Inhibited by an Antibody to Junctional Adhesion Molecule (Jam)

Journal of Experimental Medicine ◽

10.1084/jem.190.9.1351 ◽

1999 ◽

Vol 190 (9) ◽

pp. 1351-1356 ◽

Cited By ~ 199

Author(s):

Aldo Del Maschio ◽

Ada De Luigi ◽

Ines Martin-Padura ◽

Manfred Brockhaus ◽

Tamas Bartfai ◽

...

Keyword(s):

Cerebrospinal Fluid ◽

Adhesion Molecule ◽

Brain Parenchyma ◽

Immunoglobulin Superfamily ◽

Leukocyte Transmigration ◽

Leukocyte Accumulation ◽

Brain Barrier Permeability ◽

The Brain

The mechanisms that govern leukocyte transmigration through the endothelium are not yet fully defined. Junctional adhesion molecule (JAM) is a newly cloned member of the immunoglobulin superfamily which is selectively concentrated at tight junctions of endothelial and epithelial cells. A blocking monoclonal antibody (BV11 mAb) directed to JAM was able to inhibit monocyte transmigration through endothelial cells in in vitro and in vivo chemotaxis assays. In this study, we report that BV11 administration was able to attenuate cytokine-induced meningitis in mice. The intravenous injection of BV11 mAb significantly inhibited leukocyte accumulation in the cerebrospinal fluid and infiltration in the brain parenchyma. Blood–brain barrier permeability was also reduced by the mAb. We conclude that JAM may be a new target in limiting the inflammatory response that accompanies meningitis.

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Multifunctional Superparamagnetic Stiff Nanoreservoirs for Blood Brain Barrier Applications

Nanomaterials ◽

10.3390/nano9030449 ◽

2019 ◽

Vol 9 (3) ◽

pp. 449 ◽

Cited By ~ 3

Author(s):

Zulema Vargas-Osorio ◽

Andrés Da Silva-Candal ◽

Yolanda Piñeiro ◽

Ramón Iglesias-Rey ◽

Tomas Sobrino ◽

...

Keyword(s):

Endothelial Cells ◽

Vascular Endothelial Cells ◽

Neurological Diseases ◽

Developed Countries ◽

Large Set ◽

In Vivo Experiments ◽

Liver And Kidney ◽

The Brain

Neurological diseases (Alzheimer’s disease, Parkinson’s disease, and stroke) are becoming a major concern for health systems in developed countries due to the increment of ageing in the population, and many resources are devoted to the development of new therapies and contrast agents for selective imaging. However, the strong isolation of the brain by the brain blood barrier (BBB) prevents not only the crossing of pathogens, but also a large set of beneficial drugs. Therefore, an alternative strategy is arising based on the anchoring to vascular endothelial cells of nanoplatforms working as delivery reservoirs. In this work, novel injectable mesoporous nanorods, wrapped by a fluorescent magnetic nanoparticles envelope, are proposed as biocompatible reservoirs with an extremely high loading capacity, surface versatility, and optimal morphology for enhanced grafting to vessels during their diffusive flow. Wet chemistry techniques allow for the development of mesoporous silica nanostructures with tailored properties, such as a fluorescent response suitable for optical studies, superparamagnetic behavior for magnetic resonance imaging MRI contrast, and large range ordered porosity for controlled delivery. In this work, fluorescent magnetic mesoporous nanorods were physicochemical characterized and tested in preliminary biological in vitro and in vivo experiments, showing a transversal relaxivitiy of 324.68 mM−1 s−1, intense fluorescence, large specific surface area (300 m2 g−1), and biocompatibility for endothelial cells’ uptake up to 100 µg (in a 80% confluent 1.9 cm2 culture well), with no liver and kidney disability. These magnetic fluorescent nanostructures allow for multimodal MRI/optical imaging, the allocation of therapeutic moieties, and targeting of tissues with specific damage.

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Brain pharmacokinetics of two BBB penetrating bispecific antibodies of different size

Fluids and Barriers of the CNS ◽

10.1186/s12987-021-00257-0 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Rebecca Faresjö ◽

Gillian Bonvicini ◽

Xiaotian T. Fang ◽

Ximena Aguilar ◽

Dag Sehlin ◽

...

Keyword(s):

Ex Vivo ◽

Elimination Rate ◽

Brain Parenchyma ◽

Bispecific Antibodies ◽

Igg Antibody ◽

Nuclear Track Emulsion ◽

Ex Vivo Autoradiography ◽

The Brain

Abstract Background Transferrin receptor (TfR1) mediated enhanced brain delivery of antibodies have been studied extensively in preclinical settings. However, the brain pharmacokinetics, i.e. brain entry, distribution and elimination are still not fully understood for this class of antibodies. The overall aim of the study was to compare the brain pharmacokinetics of two BBB-penetrating bispecific antibodies of different size (210 vs 58 kDa). Specifically, we wanted to investigate if the faster systemic clearance of the smaller non-IgG antibody di-scFv3D6-8D3, in comparison with the IgG-based bispecific antibody mAb3D6-scFv8D3, was also reflected in the brain. Methods Wild-type (C57/Bl6) mice were injected with 125I-iodinated ([125I]) mAb3D6-scFv8D3 (n = 46) or [125I]di-scFv3D6-8D3 (n = 32) and euthanized 2, 4, 6, 8, 10, 12, 16, or 24 h post injection. Ex vivo radioactivity in whole blood, peripheral organs and brain was measured by γ-counting. Ex vivo autoradiography and nuclear track emulsion were performed on brain sections to investigate brain and parenchymal distribution. Capillary depletion was carried out at 2, 6, and 24 h after injection of [125I]mAb3D6-scFv8D3 (n = 12) or [125I]di-scFv3D6-8D3 (n = 12), to estimate the relative levels of radiolabelled antibody in brain capillaries versus brain parenchyma. In vitro binding kinetics for [125I]mAb3D6-scFv8D3 or [125I]di-scFv3D6-8D3 to murine TfR were determined by LigandTracer. Results [125I]di-scFv3D6-8D3 showed faster elimination from blood, lower brain Cmax, and Tmax, a larger parenchymal-to-capillary concentration ratio, and a net elimination from brain at an earlier time point after injection compared with the larger [125I]mAb3D6-scFv8D3. However, the elimination rate from brain did not differ between the antibodies. The study also indicated that [125I]di-scFv3D6-8D3 displayed lower avidity than [125I]mAb3D6-scFv8D3 towards TfR1 in vitro and potentially in vivo, at least at the BBB. Conclusion A smaller size and lower TfR1 avidity are likely important for fast parenchymal delivery, while elimination of brain-associated bispecific antibodies may not be dependent on these characteristics.

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Diabetes-related sex differences in the brain endothelin system following ischemia in vivo and in human brain endothelial cells in vitro

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2019-0630 ◽

2020 ◽

Vol 98 (9) ◽

pp. 587-595 ◽

Cited By ~ 2

Author(s):

Yasir Abdul ◽

Weiguo Li ◽

Juan D. Vargas ◽

Emily Grant ◽

Lianying He ◽

...

Keyword(s):

Endothelial Cells ◽

Sex Differences ◽

Cell Types ◽

Diabetic Rats ◽

Receptor Subtype ◽

Endothelin System ◽

Eta Receptor ◽

The Brain

The endothelin (ET) system has been implicated to contribute to the pathophysiology of cognitive impairment and stroke in experimental diabetes. Our goals were to test the hypotheses that (1) circulating and (or) periinfarct ET-1 levels are elevated after stroke in both sexes and this increase is greater in diabetes, (2) ET receptors are differentially regulated in the diabetic brain, (3) brain microvascular endothelial cells (BMVEC) of female and male origin express the ETA receptor subtype, and (4) diabetes- and stroke-mimicking conditions increase ET-1 levels in BMVECs of both sexes. Control and diabetic rats were randomized to sham or stroke surgery. BMVECs of male (hBEC5i) and female (hCMEC/D3) origin, cultured under normal and diabetes-mimicking conditions, were exposed to normoxia or hypoxia. Circulating ET-1 levels were higher in diabetic animals and this was more pronounced in the male cohort. Stroke did not further increase plasma ET-1. Tissue ET-1 levels were increased after stroke only in males, whereas periinfarct ET-1 increased in both control and diabetic females. Male BMVECs secreted more ET-1 than female cells and hypoxia increased ET-1 levels in both cell types. There was sexually dimorphic regulation of ET receptors in both tissue and cell culture samples. There are sex differences in the stroke- and diabetes-mediated changes in the brain ET system at the endothelial and tissue levels.

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Fluorescent Imaging of Amyloid-β Deposits in Brain: An Overview of Probe Development and a Highlight of the Applications for In Vivo Imaging

Current Medicinal Chemistry ◽

10.2174/0929867325666180214110024 ◽

2018 ◽

Vol 25 (23) ◽

pp. 2736-2759 ◽

Cited By ~ 5

Author(s):

Hualong Fu ◽

Mengchao Cui

Keyword(s):

Fluorescent Probes ◽

Rapid Development ◽

Light Attenuation ◽

Disease Onset ◽

Amyloid Β ◽

Brain Parenchyma ◽

Fluorescent Imaging ◽

The Brain

The β-amyloid (Aβ) plaques presented within the brain parenchyma have been widely proved to be one of the hallmarks of Alzheimer’s disease (AD). According to the amyloid cascade hypothesis, the accumulation of Aβ plaques in the brain is intrinsic and fundamental for disease onset, and much research about the early diagnosis of AD is based on this. A recent development in Aβ detection has focused on the mapping of the molecule events in the brain using an exquisite, noninvasive, and inexpensive optical imaging technique, which has stimulated the rapid development of Aβ-specific fluorescent probes. Among them, nearinfrared (NIR) fluorophores have gained adequate attention due to the weak light attenuation in tissues and avoidance from auto-fluorescence of biological matter. In this review, we showcase the current developments of fluorescent probes that are subject to in vitro or in vivo detection of Aβ plaques in the brain, and give an emphasis on the probes used for in vivo twophoton microscopy and NIR imaging by highlighting their biological and photochemical properties.

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Functionalised LRP1 targeted carbon nanotubes across the blood-brain barrier in vitro and in vivo after intravenous injection

Neuro-Oncology ◽

10.1093/neuonc/noz167.011 ◽

2019 ◽

Vol 21 (Supplement_4) ◽

pp. iv3-iv3

Author(s):

Julie Wang ◽

Houmam Kafa ◽

Noelia Rubio ◽

Sukhvinder Bansal ◽

Frederic Festy ◽

...

Keyword(s):

Carbon Nanotubes ◽

Blood Brain Barrier ◽

Intravenous Injection ◽

Brain Parenchyma ◽

Brain Barrier ◽

Brain Targeting ◽

Blood Brain ◽

The Brain

Abstract Despite extensive research in drug development, brain cancer is still lacking an efficacious cure due to the inability to deliver current therapeutics to the brain across the blood-brain barrier (BBB). Chemically functionalized carbon nanotubes (f-CNT) constitute a novel class of nanomaterials with attractive physical, chemical and electronic properties. The key advantage of f-CNTs is the extremely high surface area to size ratio allowing a high degree of chemical functionalization making them invaluable tools for designing drug delivery systems to the brain. One of the most interesting characteristics of f-CNTs is their ability to translocate across plasma membranes and enter the cells either passively by direct translocation across membranes or actively via endocytosis. Herein, we confirmed the ability of f-CNTs to cross the BBB and reach the brain in in vitro using a co-culture model of PBEC and primary rat astrocytes and in vivo after intravenous injection. Thanks to their unique optical properties, the uptake of f-CNT in brain was confirmed using state-of-the-art spectroscopic imaging techniques such as multi-photon luminescence imaging, fluorescence lifetime microscopy and Raman spectroscopy. Conjugation with angiopep-2 (ANG), a small peptide targeting the LRP1 receptor overexpressed in the BBB and glioma cells, further enhanced brain parenchyma accumulation in healthy brains. Higher uptake in glioma than brain parenchyma was also observed in glioma-bearing mice after intravenous administration. The inherent brain accumulation ability of f-CNTs coupled with improved brain-targeting by ANG favours the future clinical applications of f-CNTs-ANG to deliver active therapeutics for brain glioma therapy.

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