Diese Arbeit wurde durch ein Stipendium der National Institutes of Health, R01CA142928 unterstützt.

Ein. Intravenöse Injektion von Evans Blue in der Maus laterale Schwanzvene <ol><li> Bereiten Sie eine 0,5% sterile Lösung von Evans-Blau in PBS. Falls notwendig, Filter-sterilisiert die Lösung, um Partikel, die nicht aufgelöst hat, zu entfernen. </li><li> Absaugen 200 ul Evans Blue-Lösung in einer Spritze. Vermeiden Sie alle Luftblasen, die in die Spritze entgangen sein könnte. </li><li> Ort Mäusen, 8-12 Wochen alt sind in eine Rückhaltevorrichtung so dass das Tier nicht frei beweglich, sondern mit dem Schwanz gehandhabt werden kann. </li><li> Die Maus Rückhaltevorrichtung auf die Seite, so dass die laterale Schwanzvene gut sichtbar und sind nach oben gerichtet. </li><li> Halten auf das Endstück mit der nicht dominanten Hand zwischen dem Daumen und dem Zeigefinger. </li><li> Sie mit der Nadel (kleine Spurweite, 27-30) bei einer 10 bis 15 Grad Winkel, Abschrägung, voraus in die laterale Schwanzvene in die Richtung des Kopfes. Halten Sie die Nadel und Spritze parallel zum Schwanz. </li><li> Do nicht anwendbar Gegendruck auf die richtige Platzierung zu bestätigen, da dies die Vene zusammenbrechen könnte. </li><li> Langsam spritzen 200 ul Evans-Blau-Lösung in die Schwanzvene der Maus. </li><li> Beachten Sie die Leichtigkeit, mit der der Kolben Fortschritte, denn dies ist der Beweis für die korrekte Platzierung der Nadel in der Vene. </li><li> Legen Sie die Maus wieder in seinen Käfig und beobachten Sie es für 30 min. </li></ol> 2. Orgel Sammlung und Extraktion von Evans Blue von den Organen <ol><li> Opfert die Mäuse durch Genickbruch. For Miles Assayzwecke Genickbruch wird empfohlen, da es wesentliche Beeinflussung begrenzt mit vaskulären Permeabilität. Opfern alle Mäuse gleichzeitig, so schnell wie möglich. Arbeiten Sie mit Kohorten von 6 Mäusen oder weniger, denn kurz nach dem Tod Blutgefäße durchlässiger geworden. </li><li> Platzieren Sie die Maus auf den Rücken und setzen ihre Füße auf einer weißen Tafel. </li><li> Öffnen Sie die Bauch-und Brusthöhle zu thor aussetzenACIC und Bauchorgane. </li><li> Nehmen repräsentative Bilder von Unterschieden in Evans Blue Extravasation zeigen. Fügen Sie alle Mäuse in dem selben Gebiet, um identische Lichtverhältnisse für alle Mäuse haben. </li><li> Sammle Organe von Interesse und steckte sie in 1,5 ml Röhrchen </li><li> Wiegen Leerhülse und bringen den Saldowert Null. </li><li> Übertragen der Gewebeprobe und gewichtet sie. Wiederholen Sie dies für alle Gewebeproben. Gewebe können luftgetrocknet werden, um den Wassergehalt Variabilität zwischen verschiedenen Organen zu eliminieren. </li><li> . Fügen Sie 500 ul Formamid zu jeder Gewebeprobe Röhre. </li><li> Übertragen Sie alle Rohre mit einem 55 ° C Wasserbad oder Heizblock. Inkubieren 24-48 h bis Evans Blue aus dem Gewebe zu extrahieren. </li></ol> 3. Quantifizierung von Evans Blue extravasierten in interstitiellen Gewebe <ol><li> Zentrifugieren Formamid / Evans Blue Mischung Pellet alle verbleibenden Gewebefragmente. </li><li> Absorption bei 610nm aufweist. Verwenden Sie 500 ul Formamid als leer. </li><li> Calculate ng Evans Blue pro mg Gewebe ausgetretenes. </li><li> Zeichnen Sie alle Daten in einer Grafik. </li><li> Statistische Analysen durchzuführen, um signifikante Unterschiede festzustellen. </li></ol>

<ol>
	<li>Beck, K. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inducible+NO+synthase:+role+in+cellular+signaling.">Inducible NO synthase: role in cellular signaling.</a> J. Exp. Biol. 202, 645-653 (1999).</li><li>Bertglia, S., Giusti, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+nitric+oxide+in+capillary+perfusion+and+oxygen+delivery+regulation+during+systemic+hypoxia.">Role of nitric oxide in capillary perfusion and oxygen delivery regulation during systemic hypoxia.</a> Am. J. Physiol. Heart Circ. Physiol. 288, H525-H531 (2005).</li><li>Miles, A. A., Miles, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascular+reactions+to+histamine,+histamine-liberator+and+leutaxine+in+the+skin+of+guinea+pigs.">Vascular reactions to histamine, histamine-liberator and leutaxine in the skin of guinea pigs.</a> J. Physiol. (London). 118, 228-257 (1952).</li><li>Weis, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascular+permeability+in+cardiovascular+disease+and+cancer.">Vascular permeability in cardiovascular disease and cancer.</a> Curr. Opin. Hematol. 15, 243-249 (2008).</li><li>Kumar, P., Shen, Q., Pivetii, C. D., Lee, E. S., We, M. H., Yuan, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+mechanisms+of+endothelial+hyperpermeability:+implications+in+inflammation.">Molecular mechanisms of endothelial hyperpermeability: implications in inflammation.</a> Expert Rev. Mol. Med. 30, 11-19 (2009).</li><li>Viazzi, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vascular+permeability,+blood+pressure,+and+organ+damage+in+primary+hypertension.">Vascular permeability, blood pressure, and organ damage in primary hypertension.</a> Hypertens. Res. 31, 873-879 (2008).</li><li>Scheppke, ., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+vascular+permeability+suppression+by+topical+application+of+a+novel+VEGFR2/Src+kinase+inhibitor+in+mice+and+rabbits.">Retinal vascular permeability suppression by topical application of a novel VEGFR2/Src kinase inhibitor in mice and rabbits.</a> J. Clin. Invest. 118, 2337-2346 (2008).</li><li>Blanchet, M. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loss+of+CD34+Leads+To+Exacerbated+Autoimmune+Arthritis+through+Increased+Vascular+Permeability.">Loss of CD34 Leads To Exacerbated Autoimmune Arthritis through Increased Vascular Permeability.</a> J. Immunol. 184, 1292-1299 (2010).</li><li>Dvorak, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mast+cell-derived+mediators+of+enhanced+microvascular+permeability,+vascular+permeability+factor/vascular+endothelial+growth+factor,+histamine,+and+serotonin,+cause+leakage+of+macromolecules+through+a+new+endothelial+cell+permeability+organelle,+the+vesiculo-vacuolar+organelle.">Mast cell-derived mediators of enhanced microvascular permeability, vascular permeability factor/vascular endothelial growth factor, histamine, and serotonin, cause leakage of macromolecules through a new endothelial cell permeability organelle, the vesiculo-vacuolar organelle.</a> Chem. Immunol. Allergy. 85, 185-204 (2005).</li><li>Le Guelte, A., Gavard, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+endothelial+cell-cell+junctions+in+endothelial+permeability.">Role of endothelial cell-cell junctions in endothelial permeability.</a> Methods Mol. Biol. 763, 265-279 (2011).</li><li>Martins-Green, M., Petreaca, M., Yao, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+assay+system+for+in+vitro+detection+of+permeability+in+human+"endothelium".">An assay system for in vitro detection of permeability in human "endothelium".</a> Methods Enzymol. 443, 137-153 (2008).</li></ol>

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Gefäßpermeabilität ist ein kritischer Marker für Blutgefäß-Status. Erhöhte Gefäßpermeabilität hat sich gezeigt, dass in mehreren systemischen Erkrankungen, wie Diabetes, Hypertension, und Autoimmunerkrankungen 6,7,8 vorliegt. Erhöhte Gefäßpermeabilität ist gezeigt worden, durch Scherbeanspruchung vermittelt werden, Wachstumsfaktoren wie vaskulären endothelialen Wachstumsfaktor und Fibroblasten-Wachstumsfaktor, Entzündungsmediatoren wie Serotonin, Histamin und Bradykinin 9. Extravasa...

Bildung und Erhaltung der selektiven permeablen Barrieren für die richtige Entwicklung der Organe und Leistung 1,2 unerlässlich. Endothelzellen Linie das Blutgefäßlumen und bilden eine semi-permeable Barriere, die wesentlich in den selektiven Transport zwischen Blut und dem interstitiellen Raum aller Organe ist. Eine ausreichende Permeabilitätsbarriere wird durch enge Zell-zu-Zell-Verbindungen, die ausschließlich durch Wachstumsfaktoren, Zytokine und andere stressbedingte Moleküle 3 gesteuert werden beibehalten. Störung der Endothelzelle Barriere kann in erhöhter Permeabilität und vaskuläre Leckage führen. Diese Effekte sind in verschiedenen Krankheitsstadien gesehen und das Verständnis der Unterstreichung molekularen Signalwegen erfordert multidisziplinäre Methoden 4,5. In diesem Artikel beschreiben wir ein Verfahren zur In-vivo-Verwendung eines Gefäßpermeabilität Mausmodell messen. Der Assay wir beschreiben, auch als Miles-Assay bezeichnet, ist ein gut establIshed Methode, um vaskuläre Permeabilität in vivo zu testen. Der Assay basiert auf der Tatsache, dass unter basalen physiologischen Bedingungen, Albumin passiert nicht die Endothelbarriere basiert. Evans Blue, ein Azofarbstoff mit hoher Affinität für Albumin, wird in den Blutstrom eines Versuchstiers injiziert werden, und unter physiologischen Bedingungen, so wird erwartet, dass sie innerhalb von Blutgefäßen beschränkt werden. Wenn ein Gefäßpermeabilität Reiz hinzugefügt wird, entweder lokal oder systemisch, beginnen die Blutgefäße zu Protein auslaufen und damit auch die Evans Blau, das an Albumin gebunden ist. Dies führt zu einem raschen bläuliche Färbung von Geweben durchlässigen Behälter haben. Erfolgreiche Injektion des Farbstoffes in der Maus laterale Schwanzvene ist entscheidend für die gute Ergebnis des Experiments. Schwanzveneninjektion Technik erfordert umfangreiche Praxis und sollte vor dem Start des Experiments gemeistert werden. Gefäßpermeabilität ist stark abhängig von dem Alter und dem Gewicht des eineimal, so beim Vergleich verschiedener Mausstämmen ist es unerlässlich, dass die Mäuse oder andere Probanden nahezu identisch Geburtsdaten und Gewicht haben. Andere Faktoren, die die Durchlässigkeit der Endothelbarriere beeinflussen Umgebungsbedingungen wie Temperatur, Feuchtigkeit, was sehr wichtig, die Handhabung Stress der Maus. Aufgrund der Vielzahl von Faktoren, die das Ergebnis des Experiments beeinflussen kann es immer ratsam, dass das Experiment wiederholt wird mindestens dreimal und statistische Analysen durchgeführt. Dieser Assay kann oder verwendet werden, um Gefäßpermeabilität von Mäusen, die gentechnisch verändert wurden, sowie Mäuse mit unterschiedlichen genetischen Hintergründen vergleichen. Permeabilität kann in Gegenwart oder Abwesenheit eines Reizes bewertet werden, in Abhängigkeit von der Funktion des Gens, das moduliert ist. Dieser Assay kann auch verwendet werden, oder um die Wirkung von unterschiedlichen Verbindungen auf Gefäßpermeabilität testen.

<table border="1"><tbody><tr><td></td><td></td><td></td><td> REAGENT </td></tr><tr><td> EVANS BLUE </td><td> SIGMA </td><td> E2129 </td><td></td></tr><tr><td> FORMAMIDE </td><td> INVITROGEN </td><td> 15515-026 </td><td></td></tr><tr><td> PBS </td><td></td><td></td><td> 0,2 M Phosphat 1,5 M NaCl pH 7,4 </td></tr><tr><td></td><td></td><td></td><td> EQUIPMENT </td></tr><tr><td> SPEKTRALPHOTOMETER </td><td> EPPENDORF </td><td> 952000006 </td><td></td></tr><tr><td> MOUSE Rückhaltevorrichtung </td><td> Harvard Apparatus </td><td> 340012 </td><td></td></tr><tr><td> SPRITZE </td><td> BD </td><td> 309659 </td><td></td></tr><tr><td> NADELN </td><td> BD </td><td> 305106 </td><td> Die Spurweite der Nadel hängt von der Größe des Tieres. </td></tr><tr><td> BALANCE </td><td> DENVER INSTRUMENT </td><td> TP-64 </td><td></td></tr></tbody></table>

an in vivo assay to test blood vessel permeability

Dieses Verfahren basiert auf der intravenösen Injektion von Evans Blue in Mäusen als Versuchstiere Modell. Evans Blau ist ein Farbstoff, der Albumin bindet. Unter physiologischen Bedingungen das Endothel ist undurchlässig für Albumin, so Evans blue gebundene Albumin Überreste innerhalb von Blutgefäßen beschränkt. In pathologischen Bedingungen, die erhöhte Gefäßpermeabilität Endothelzellen fördern teilweise verlieren ihren engen Kontakt und das Endothel durchlässig wird, um kleine Proteine ​​wie Albumin. Dieser Zustand ermöglicht Extravasation von Evans Blue in den Geweben. Eine gesunde Endothel verhindert Extravasation des Farbstoffs in den benachbarten vaskularisierten Geweben. Organe mit einer erhöhten Permeabilität deutlich erhöht Blaufärbung Vergleich zu Organen mit intaktem Endothel zeigen. Das Niveau der Gefäßpermeabilität kann durch einfache Visualisierung oder durch quantitative Messung der Farbstoff pro Milligramm Gewebe Kontrolle gegenüber Versuchstier / Gewebe eingebaut beurteilt werden. Zwei powerful Aspekte dieses Assays sind seine Einfachheit und quantitativen Merkmalen. Evans Blau-Farbstoff kann aus Geweben, die durch Inkubieren eines bestimmten Menge an Gewebe in Formamid extrahiert werden. Evans Blue Absorptionsmaximum liegt bei 620 nm und Absorption Minimum bei 740 nm auf. Durch die Verwendung einer Standardkurve für Evans Blue, können Messungen der optischen Dichte in Milligramm Farbstoff pro Milligramm Gewebe eingefangen umgewandelt werden. Statistische Analyse sollte verwendet werden, um signifikante Unterschiede in Gefäßpermeabilität zu beurteilen.

Wir haben eine in vivo Durchlässigkeit Assay zum Schiff Leck in Mäusen 8-12 Wochen alt zu testen. Dieser Test ist nützlich beim Vergleich der relativen Gefäßpermeabilität zwischen Tieren unterschiedlicher genetischer Hintergrund oder in einem einzelnen Stamm von Mäusen unterworfen Behandlungen, die das Gefäßsystem beeinflussen. Unsere Ergebnisse zeigen, dass ein Stamm von genetisch veränderten Mäusen wir in unserem Labor erstellt eine durchlässige Endothel im Vergleich zu Wildtyp-Mäusen hat. Diese ...

Watch this Scientific Journal Video about An in vivo Assay to Test Blood Vessel Permeability at JoVE.com

An in vivo Assay to Test Blood Vessel Permeability

Wir präsentieren ein<em&gt; In vivo</em&gt; Assay Blutgefäß Durchlässigkeit zu testen. Dieser Assay basiert auf intravenöse Injektion eines Farbstoffes und nachfolgender Visualisierung dessen Diffusion in Zwischenräume basiert.

Ein<em&gt; In vivo</em&gt; Assay Blood Vessel Durchlässigkeitsprüfung

This method is based on the intravenous injection of Evans Blue in mice as the test animal model. Evans blue is a dye that binds albumin. Under ...

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Research

JoVE Journal

Medicine

An in vivo Assay to Test Blood Vessel Permeability

64.4K Aufrufe.  Fox Chase Cancer Center. Wir präsentieren ein In vivo Assay Blutgefäß Durchlässigkeit zu testen. Dieser Assay basiert auf intravenöse Injektion eines Farbstoffes und nachfolgender Visualisierung dessen Diffusion in Zwischenräume basiert.

Serie: An in vivo Assay to Test Blood Vessel Permeability

In Vitro Assays to Assess Blood-brain Barrier Mesh-like Vessel Formation and Disruption

Blood-brain barrier (BBB) coverage plays a central role in the homeostasis of the central nervous system (CNS). The BBB is dynamically maintained by astrocytes, pericytes and brain endothelial cells (BECs). Here, we detail methods to assess BBB coverage using single cultures of immortalized human BECs, single cultures of primary mouse BECs, and a humanized triple culture model (BECs, astrocytes and pericytes) of the BBB. To highlight the applicability of the assays to disease states, we describe the effect of oligomeric amyloid-&#946; (oA&#946;), which is an important contributor to Alzheimer&#39;s disease (AD) progression, on BBB coverage. Further, we utilize the epidermal growth factor (EGF) to illuminate the drug screening potential of the techniques. Our results show that single and triple cultured BECs form meshwork-like structures under basal conditions, and that oA&#946; disrupts this cell meshwork formation and degenerates the preformed mesh structures, but EGF blocks this disruption. Thus, the techniques described are important for dissecting fundamental and disease-relevant processes that modulate BBB coverage.

In Vitro Assays to Assess Blood-brain Barrier Mesh-like Vessel Formation and Disruption

Maintaining blood-brain barrier coverage is key for the homeostasis of the central nervous system. This protocol describes in vitro techniques to delineate the fundamental and pathological processes that modulate blood-brain barrier coverage.

In-Vitro- Assays zur Beurteilung der Blut-Hirn-Schranke Mesh-artigen Gefäßbildung und -störung

Blood-brain barrier (BBB) coverage plays a central role in the homeostasis of the central nervous system (CNS). The BBB is dynamically maintained by ...

Forschung

Medizin

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains brain homeostasis. The principal sites of the barrier are endothelial cells of the brain capillaries whose barrier function results from tight intercellular junctions and efflux transporters expressed on the plasma membrane. This function is regulated by pericytes and astrocytes that together form the neurovascular unit (NVU). Several neurological diseases such as stroke, Alzheimer&#39;s disease (AD), brain tumors are associated with an impaired BBB function. Assessment of the BBB permeability is therefore crucial in evaluating the severity of the neurological disease and the success of the treatment strategies employed.
We present here a simple yet robust permeability assay that have been successfully applied to several mouse models both, genetic and experimental. The method is highly quantitative and objective in comparison to the tracer fluorescence analysis by microscopy that is commonly applied. In this method, mice are injected intraperitoneally with a mix of aqueous inert fluorescent tracers followed by anesthetizing the mice. Cardiac perfusion of the animals is performed prior to harvesting brain, kidneys or other organs. Organs are homogenized and centrifuged followed by fluorescence measurement from the supernatant. Blood drawn from the cardiac puncture just before perfusion serves for normalization purpose to the vascular compartment. The tissue fluorescence is normalized to the wet weight and serum fluorescence to obtain a quantitative tracer permeability index. For additional confirmation, the contralateral hemi-brain preserved for immunohistochemistry can be utilized for tracer fluorescence visualization purposes.

An In Vivo Blood-brain Barrier Permeability Assay in Mice Using Fluorescently Labeled Tracers

Here we present a mouse brain vascular permeability assay using intraperitoneal injection of fluorescent tracers followed by perfusion that is applicable to animal models of blood-brain barrier dysfunction. One hemi-brain is used for assessing permeability quantitatively and the other for tracer visualization/immunostaining. The procedure takes 5 - 6 h for 10 mice.

Eine In Vivo Blut - Hirn-Schranke Permeabilität Assay bei Mäusen mit Gewebekulturen beschriftet Tracer

Blood-brain barrier (BBB) is a specialized barrier that protects the brain microenvironment from toxins and pathogens in the circulation and maintains ...

Neurowissenschaften

An In Vivo Method for Evaluating the Gut-Blood Barrier and Liver Metabolism of Microbiota Products

The gut-blood barrier (GBB) controls the passage of nutrients, bacterial metabolites and drugs from intestinal lumen to the bloodstream. The GBB integrity is disturbed in gastrointestinal, cardiovascular and metabolic diseases, which may result in easier access of biologically active compounds, such as gut bacterial metabolites, to the bloodstream. Thus, the permeability of the GBB may be a marker of both intestinal and extraintestinal diseases. Furthermore, the increased penetration of bacterial metabolites may affect the functioning of the entire organism.
Commonly used methods for studying the GBB permeability are performed ex vivo. The accuracy of those methods is limited, because the functioning of the GBB depends on intestinal blood flow. On the other hand, commonly used in vivo methods may be biased by liver and kidney performance, as those methods are based on evaluation of urine or/and peripheral blood concentrations of exogenous markers. Here, we present a direct measurement of GBB permeability in rats using an in vivo method based on portal blood sampling, which preserves intestinal blood flow and is virtually not affected by the liver and kidney function. 
Polyurethane catheters are inserted into the portal vein and inferior vena cava just above the hepatic veins confluence. Blood is sampled at baseline and after administration of a selected marker into a desired part of the gastrointestinal tract. Here, we present several applications of the method including (1) evaluation of the colon permeability to TMA, a gut bacterial metabolite, (2) evaluation of liver clearance of TMA, and (3) evaluation of a gut-portal blood-liver-peripheral blood pathway of gut bacteria-derived short-chain fatty acids. Furthermore, the protocol may also be used for tracking intestinal absorption and liver metabolism of drugs or for measurements of portal blood pressure.

An In Vivo Method for Evaluating the Gut-Blood Barrier and Liver Metabolism of Microbiota Products

The access of nutrients, microbiota metabolites and medicines to the circulation is controlled by the gut-blood barrier (GBB). We describe a direct method for measuring the GBB permeability in vivo, which, in contrast to commonly used indirect methods, is virtually not affected by liver and kidney functions.

Eine In Vivo -Methode zur Bewertung der Darm-Blut-Schranke und LEBERSTOFFWECHSEL Mikrobiota Produkte

The gut-blood barrier (GBB) controls the passage of nutrients, bacterial metabolites and drugs from intestinal lumen to the bloodstream. The GBB integrity ...

Quantifying Single Microvessel Permeability in Isolated Blood-perfused Rat Lung Preparation

The isolated blood-perfused lung preparation is widely used to visualize and define signaling in single microvessels. By coupling this preparation with real time imaging, it becomes feasible to determine permeability changes in individual pulmonary microvessels. Herein we describe steps to isolate rat lungs and perfuse them with autologous blood. Then, we outline steps to infuse fluorophores or agents via a microcatheter into a small lung region. Using these procedures described, we determined permeability increases in rat lung microvessels in response to infusions of bacterial lipopolysaccharide. The data revealed that lipopolysaccharide increased fluid leak across both venular and capillary microvessel segments. Thus, this method makes it possible to compare permeability responses among vascular segments and thus, define any heterogeneity in the response. While commonly used methods to define lung permeability require postprocessing of lung tissue samples, the use of real time imaging obviates this requirement as evident from the present method. Thus, the isolated lung preparation combined with real time imaging offers several advantages over traditional methods to determine lung microvascular permeability, yet is a straightforward method to develop and implement.

The isolated blood-perfused lung preparation makes it feasible to visualize microvessel networks on the lung surface. Here we describe an approach to quantify permeability of single microvessels in isolated lungs using real time fluorescence imaging.

Quantifizierung der Mikrogefäßdurchlässigkeit im Einzel isolierten Blutdurchbluteten Lungen Rat Vorbereitung

The isolated blood-perfused lung preparation is widely used to visualize and define signaling in single microvessels. By coupling this preparation with ...

Biologie

Microperfusion Technique to Investigate Regulation of Microvessel Permeability in Rat Mesentery

Experiments to measure the permeability properties of individually perfused microvessels provide a bridge between investigation of molecular and cellular mechanisms regulating vascular permeability in cultured endothelial cell monolayers and the functional exchange properties of whole microvascular beds. A method to cannulate and perfuse venular microvessels of rat mesentery and measure the hydraulic conductivity of the microvessel wall is described. The main equipment needed includes an intravital microscope with a large modified stage that supports micromanipulators to position three different microtools: (1) a beveled glass micropipette to cannulate and perfuse the microvessel; (2) a glass micro-occluder to transiently block perfusion and enable measurement of transvascular water flow movement at a measured hydrostatic pressure, and (3) a blunt glass rod to stabilize the mesenteric tissue at the site of cannulation. The modified Landis micro-occlusion technique uses red cells suspended in the artificial perfusate as markers of transvascular fluid movement, and also enables repeated measurements of these flows as experimental conditions are changed and hydrostatic and colloid osmotic pressure difference across the microvessels are carefully controlled. Measurements of hydraulic conductivity first using a control perfusate, then after re-cannulation of the same microvessel with the test perfusates enable paired comparisons of the microvessel response under these well-controlled conditions. Attempts to extend the method to microvessels in the mesentery of mice with genetic modifications expected to modify vascular permeability were severely limited because of the absence of long straight and unbranched microvessels in the mouse mesentery, but the recent availability of the rats with similar genetic modifications using the CRISPR/Cas9 technology is expected to open new areas of investigation where the methods described herein can be applied.

The modified Landis technique enables paired measurement of the hydraulic conductivity of individual microvessels in the mesentery of normal and genetically modified rats under control and test conditions using microperfusion techniques. It provides a convenient method to evaluate mechanisms that regulate microvessel permeability and transvascular exchange under physiological conditions.

Mikroperfusion Technik zur Untersuchung von Mikrogefäßdurchlässigkeit Verordnung in Rattengekröse

Experiments to measure the permeability properties of individually perfused microvessels provide a bridge between investigation of molecular and cellular ...

In Vivo Study of Human Endothelial-Pericyte Interaction Using the Matrix Gel Plug Assay in Mouse

Angiogenesis is the process by which new blood vessels are formed from existing vessels. New vessel growth requires coordinated endothelial cell proliferation, migration, and alignment to form tubular structures followed by recruitment of pericytes to provide mural support and facilitate vessel maturation. Current in vitro cell culture approaches cannot fully reproduce the complex biological environment where endothelial cells and pericytes interact to produce functional vessels. We present a novel application of the in vivo matrix gel plug assay to study endothelial-pericyte interactions and formation of functional blood vessels using severe combined immune deficiency mutation (SCID) mice. Briefly, matrix gel is mixed with a solution containing endothelial cells with or without pericytes followed by injection into the back of anesthetized SCID mice. After 14 days, the matrix gel plugs are removed, fixed and sectioned for histological analysis. The length, number, size and extent of pericyte coverage of mature vessels (defined by the presence of red blood cells in the lumen) can be quantified and compared between experimental groups using commercial statistical platforms. Beyond its use as an angiogenesis assay, this matrix gel plug assay can be used to conduct genetic studies and as a platform for drug discovery. In conclusion, this protocol will allow researchers to complement available in vitro assays for the study of endothelial-pericyte interactions and their relevance to either systemic or pulmonary angiogenesis.

In Vivo Study of Human Endothelial-Pericyte Interaction Using the Matrix Gel Plug Assay in Mouse

We present a protocol to study human endothelial-pericyte interactions in mouse using a variation of the matrix gel plug angiogenesis assay.

In - vivo - Studie der menschlichen Endothelial-pericyte Interaktion Mit dem Matrix - Gel - Plug - Assay in der Maus

Angiogenesis is the process by which new blood vessels are formed from existing vessels. New vessel growth requires coordinated endothelial cell ...

Endothelial Cell Transcytosis Assay as an In Vitro Model to Evaluate Inner Blood-Retinal Barrier Permeability

Dysfunction of the blood-retinal barrier (BRB) contributes to the pathophysiology of several vascular eye diseases, often resulting in retinal edema and subsequent vision loss. The inner blood-retinal barrier (iBRB) is mainly composed of retinal vascular endothelium with low permeability under physiological conditions. This feature of low permeability is tightly regulated and maintained by low rates of paracellular transport between adjacent retinal microvascular endothelial cells, as well as transcellular transport (transcytosis) through them. The assessment of retinal transcellular barrier permeability may provide fundamental insights into iBRB integrity in health and disease. In this study, we describe an endothelial cell (EC) transcytosis assay, as an in vitro model for evaluating iBRB permeability, using human retinal microvascular endothelial cells (HRMECs). This assay assesses the ability of HRMECs to transport transferrin and horseradish peroxidase (HRP) in receptor- and caveolae-mediated transcellular transport processes, respectively. Fully confluent HRMECs cultured on porous membrane were incubated with fluorescent-tagged transferrin (clathrin-dependent transcytosis) or HRP (caveolae-mediated transcytosis) to measure the levels of transferrin or HRP transferred to the bottom chamber, indicative of transcytosis levels across the EC monolayer. Wnt signaling, a known pathway regulating iBRB, was modulated to demonstrate the caveolae-mediated HRP-based transcytosis assay method. The EC transcytosis assay described here may provide a useful tool for investigating the molecular regulators of EC permeability and iBRB integrity in vascular pathologies and for screening drug delivery systems.

Endothelial Cell Transcytosis Assay as an In Vitro Model to Evaluate Inner Blood-Retinal Barrier Permeability

This protocol illustrates an in vitro endothelial cell transcytosis assay as a model to evaluate inner blood-retinal barrier permeability by measuring the ability of human retinal microvascular endothelial cells to transport horseradish peroxidase across cells in caveolae-mediated transcellular transport processes.

Endothelzell-Transzytose-Assay als In-vitro-Modell zur Beurteilung der Permeabilität der inneren Blut-Retina-Barriere

Dysfunction of the blood-retinal barrier (BRB) contributes to the pathophysiology of several vascular eye diseases, often resulting in retinal edema and ...

Evaluating Vascular Hyperpermeability-inducing Agents in the Skin with the Miles Assay

The primary function of the vascular endothelium in vertebrate organisms is to serve as a barrier between the blood and each tissue of the body, whereby the permeability of the endothelium to blood cells, plasma macromolecules, and water can be adapted according to the physiological need. In certain diseases, cytokines and growth factors are released that target the endothelial barrier to transiently increase vascular permeability; however, their prolonged presence may cause chronic vascular hyperpermeability and thereby tissue-damaging edema. The Miles assay is an in vivo technique that allows researchers to study vascular hyperpermeability through the proxy measurement of vascular leakage. Here, we provide a detailed protocol on how to perform this procedure in the mouse, which is the most widely used model organism to study mammalian physiology and pathology. The procedure involves the intravenous injection of Evans blue dye to label the circulating albumin followed by multiple intradermal injections of permeability-inducing agents and vehicle control solutions into opposing flanks of the mouse. Consequently, Evans blue dye gradually leaks into the dermis, where it accumulates and can be extracted for quantification as leakage induced by the permeability-inducing agent relative to the vehicle. The Miles assay can be performed in wild type or genetically modified mouse models and may be combined with drug administration to study molecular mechanisms that regulate vascular permeability and identify agents/targets capable of inducing or blocking hyperpermeability.

Here, we present a protocol to measure the vascular leakage induced by intradermal administration of permeability promoting agents into the murine skin. This technique can be used to determine the ability of molecules to promote or inhibit vascular leakage or to study the molecular mechanisms that regulate vascular permeability.

Bewertung von vaskulären Hyperpermeability-induzierende Wirkstoffe in der Haut mit dem Meilen-Assay

The primary function of the vascular endothelium in vertebrate organisms is to serve as a barrier between the blood and each tissue of the body, whereby ...

In Vivo Vascular Permeability Detection in Mouse Submandibular Gland

Saliva plays an important role in oral and overall health. The intact endothelial barrier function of blood vessels enables saliva secretion, whereas the endothelial barrier dysfunction is related to many salivary gland secretory disorders. The present protocol describes an in vivo paracellular permeability detection method to evaluate the function of endothelial tight junctions (TJs) in mouse submandibular glands (SMG). First, fluorescence-labeled dextrans with different molecular weights (4 kDa, 40 kDa, or 70 kDa) were injected into the angular veins of mice. Afterward, the unilateral SMG was dissected and fixed in the customized holder under a two-photon laser-scanning microscope, and then images were captured for blood vessels, acini, and ducts. Utilizing this method, the real-time dynamic leakage of the different-sized tracers from blood vessels into the basal sides of the acini and even across the acinar epithelia into the ducts was monitored to evaluate the alteration of the endothelial barrier function under physiological or pathophysiological conditions.

In Vivo Vascular Permeability Detection in Mouse Submandibular Gland

In the present protocol, the endothelial barrier function of the submandibular gland (SMG) was evaluated by injecting different molecular weighted fluorescent tracers into the angular veins of test animal models in vivo under a two-photon laser-scanning microscope.

Im lebenden Organismus Nachweis der vaskulären Permeabilität in der submandibulären Drüse der Maus

Saliva plays an important role in oral and overall health. The intact endothelial barrier function of blood vessels enables saliva secretion, whereas the ...

Vereinfachung von Angiogenese-Studien mit einem modifizierten Matrix-Gel-Plug-Assay

Modified In Vivo Matrix Gel Plug Assay for Angiogenesis Studies

Several models have been developed to investigate angiogenesis in vivo. However, most of these models are complex and expensive, require specialized equipment, or are hard to perform for subsequent quantitative analysis. Here we present a modified matrix gel plug assay to evaluate angiogenesis in vivo. In this protocol, vascular cells were mixed with matrix gel in the presence or absence of pro-angiogenic or anti-angiogenic reagents, and then subcutaneously injected into the back of recipient mice. After 7 days, phosphate buffer saline containing dextran-FITC is injected via the tail vein and circulated in vessels for 30 min. Matrix gel plugs are collected and embedded with tissue embedding gel, then 12 &#181;m sections are cut for fluorescence detection without staining. In this assay, dextran-FITC with high molecular weight (~150,000 Da) can be used to indicate functional vessels for detecting their length, while dextran-FITC with low molecular weight (~4,400 Da) can be used to indicate the permeability of neo-vessels. In conclusion, this protocol can provide a reliable and convenient method for the quantitative study of angiogenesis in vivo.

Autor im Rampenlicht: Untersuchung der Angiogenese und Gefäßpermeabilität durch einen modifizierten Matrix-Gel-Plug-Assay

The method presented here can evaluate the effect of reagents on angiogenesis or vascular permeability in vivo without staining. The method uses dextran-FITC injection via the tail vein to visualize neo-vessels or vascular leakage.

Modifizierter In-vivo-Matrix-Gel-Plug-Assay für Angiogenese-Studien

Several models have been developed to investigate angiogenesis in vivo. However, most of these models are complex and expensive, require specialized ...

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