Die Autoren danken der Finanzierung durch das Department of Defense vom Kongress Regie Medical Research Programme (# W81XWH-10-1-0445), National Institutes of Health (NIH R21 HL110056) und der American Heart Association (# 11SDG4890030).

Ein. Vorbereitung und Sterilisation von Puffer und Test-Agents <ol><li> 150 mM NaCl-Puffer: Man löst 4,383 g NaCl-Kristalle in 500 ml Nanopure-Wasser. </li><li> pH-Puffer: Planen Phosphatpuffer bei pH 5,6, 6,2, 6,8 und 7,4 durch Mischen entsprechender Mengen an einbasischen und zweibasischen Natriumphosphat. Wenn Proben, bei niedrigeren pH-Werten (dh pH &lt;5,6), dann eine mehr geeigneten Puffer, wie Citrat-Puffer getestet werden sollen, zu verwenden. Buffer Rezepte sind leicht zugänglich, und ein Beispiel verwiesen wurde hier. 12 </li><li> Sterilisieren alle Puffer oben erwähnt durch eine Flasche-top Vakuumfiltervorrichtung und Re-Check-Puffer pH-Werten. </li><li> 20% Triton X-100 (positive Kontrolle): Mix 20 ml reinem Triton X-100 in 80 ml nanoreinem Wasser. Vortex kräftig und beschallen zu lösen. Hinterlegen über Nacht bei Raumtemperatur vor der Verwendung. </li></ol> 2. Vorbereitung von Erythrozyten <ol><li> Erhalten 25 ml Blut from eine anonyme menschlichen Spender direkt in K 2-EDTA-beschichteten Vacutainer Röhrchen gezogen, um Gerinnung zu verhindern. </li></ol> HINWEIS: Alle Verfahren müssen von der zuständigen Institutional Review Board (IRB) und Venenpunktion und Blutentnahme im Voraus genehmigt werden muss durch einen geschulten phlebotomist durchgeführt werden, um das Risiko für den Spender zu minimieren. Standard Phlebotomie Verfahren wurden an anderer Stelle. Veröffentlicht 13 <ol start="2"><li> Zentrifuge Blut bei 500 xg für 5 min, und markieren Ebenen der Hämatokrit (rot, untere Schicht) und Plasma (gelblich, obere Schicht) auf dem Rohr. </li><li> Absaugen Plasma vorsichtig über eine Mikropipette in bleach hinzuzufügen, und entsorgen in biologischer Abfälle. </li><li> Füllen Hämatokrit Rohr markierte Zeile (ursprüngliche Niveau von Plasma) mit 150 mM NaCl-Lösung. Cap und invertieren ein paar Mal vorsichtig mischen. Zentrifugation bei 500 xg für 5 min. </li><li> Wiederholen Sie Schritt 2,3-2,4 an Blutzellen wieder waschen. Dann saugen übernatürlichenant und ersetzen mit PBS bei pH 7,4. Invertieren mischen. </li><li> Split Blut gleichmäßig in vier Rohre, die der jeweiligen pH, die getestet werden soll. Kennzeichnen der Rohre nach jedem pH zu testenden (5.6, 6.2, 6.8, 7.4). </li><li> Zentrifuge Blut Röhrchen bei 500 xg für 5 min. Markieren Sie Ebenen an Rohren, dann absaugen Überstand. </li><li> Füllen Sie jedes Rohr markierte Zeile mit Puffer geeigneter pH-Wert (wie in 2,6 angegeben). </li><li> Etikett vier 50 ml konischen Röhrchen (eine pro pH-Test) und Pipette 49 ml PBS des geeigneten pH-Wertes in jeden konischen Rohrs. </li><li> 1 ml Erythrozyten (gleichen pH) in entsprechende Rohr für einen 1:50-Verdünnung. Sichtprüfung der verdünnten Blut, das trübe und sollte werden niederlassen, wenn sie ungestört. Wenn kein Pellet Formen haben Zellen lysiert. </li></ol> 3. Lysis Assay 96 Well Plate Setup und Quantifizierung <ol><li> Stammlösungen aller experimentellen Drug-Delivery-Agenten, bei 20x die gewünschte Endkonzentration getestet werden (Assaywerden 10 ul von Drug-Delivery-Agent + 190 ul verdünnte roten Blutkörperchen, was zu einer 1/20 Verdünnung des ursprünglichen Drug-Delivery-Agenten in die endgültige Testansatz) nehmen. Stocks von 20, 100 und 800 Mikrogramm / ml vorgeschlagen, was zu abschließenden Test Konzentrationen von 1, 5 und 40 ug / ml. </li><li> Pipet 10 ul jeder Stammlösung in V-96-Well-Platten. Für optimale Ergebnisse, laden jede Probe in dreifacher oder vierfacher. </li></ol> Hinweis: Der Einfachheit, wird empfohlen, dass eine separate 96-Well-Platte für jedes pH sollte vorbereitet sein, getestet, mit jeder Probe werden (bei ​​jeder Konzentration) geladen bei n = 3-4 pro Platte. <ol start="3"><li> Für positive Kontrollvertiefungen, mit 10 ul 20% Triton X-100. </li><li> Für negative Kontrollvertiefungen, fügen Sie 10 ul Phosphatpuffer. Verwenden Puffer bei gleichem pH getestet werden. </li><li> Pipet 190 ul verdünnte Erythrozyten (siehe 2,10) in jede Vertiefung, um sicherzustellen, Zelle Stammlösung bleibthomogenes während der Übertragung. Hinweis: Verwenden Sie Mehrkanal-Pipette, um diese Aufgabe zu vereinfachen. </li><li> Inkubieren Platten bei 37 ° C für eine Stunde (Optional: Verwenden Sie einen Orbitalschüttler oder Wippe). </li><li> Zentrifuge Platten für 5 min bei 500 xg zu pelletieren intakte Erythrozyten. Hinweis: Beim Entfernen der Platte aus der Zentrifuge und der Transport zum nächsten Schritt, pfleglich zu behandeln und sicher sein, nicht auf das Zellpellet zu stören. </li><li> Mit einer Mehrkanalpipette, dann 100 ul Überstand aus jeder Vertiefung in eine klare, mit flachem Boden 96-Well-Platte. Hinweis: Wenn das Zellpellet versehentlich für jede Probe (n) gestört, kann man erneut zentrifugieren Platte und fahren Sie dann mit Überstand Transfer. </li><li> Messen Absorption der Überstände mit einer Platte Leser. Beachten Sie, dass ein Bereich von Wellenlängen verwendet werden (400 - 541 nm) sein. </li></ol> HINWEIS: Verschiedene Platereader unterschiedliche Sättigung Punkte und Empfindlichkeiten haben, so dass die Wahl der Wellenlänge für michaßangaben davon abhängt, ob oder nicht die Hämolyse von Daten von experimentellen Proben zuverlässig gegen maximale Hämolyse normalisiert werden, wie durch Detergensbehandlung induziert. Dies erfordert eine genaue Messung der Absorptionswerte der positiven Kontrollproben. <ol start="10"><li> Mit Microsoft Excel oder einer ähnlichen Software zur Datenanalyse, den Durchschnitt der Hintergrundabsorption Lesungen aus den negativen Kontrollproben für jeden pH-Wert (Schritt 3,4) eingestellt. Subtrahieren diesem Hintergrund Extinktionswert von allen anderen Proben, die bei diesem pH-Wert gemessen wurden. </li><li> Nach Subtraktion des Hintergrunds, finden die durchschnittliche Absorption der positiven Kontroll-Waschmittel-behandelten Proben (Schritt 3,3). Dann normalisieren alle experimentellen Daten zu dieser Extinktionmittelwert, was sollte 100% Hämolyse darstellen. Schließlich multiplizieren jede Kavität Wert mit 100% bis% Hämolyse, die in jeder einzelnen Vertiefung relativ zu dem Detergens Kontrolle aufgetreten berechnen. </li></ol>

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IRB-Zulassung: Verfahren am Menschen wurden von der Vanderbilt University Institutional Review Board (IRB; Protokoll # 111251) genehmigt worden. Keine Interessenskonflikte erklärt.

pH-empfindlichen Polymeren oder anderen Mitteln zur endosomolytischen Funktion konstruiert sein kann rasch und effektiv bezogen auf die Lyse der roten Blutzellen bei pH-Werten im Endosom angetroffen (Abbildung 1 gescreent; pH 6,8 - frühe Endosom, pH 6,2 - späte Endosom, pH 5,6 - Lysosom). 14-17 pH-abhängigen Hämolyse wurde verwendet, um die Fähigkeit von Trägern zu endosomalen Freisetzung biomakromolekulare Therapeutika (z. B. Peptide, siRNA, ODNs, Proteine) vermitteln screenen...

Obwohl es viele potenzielle high-impact therapeutische Ziele innerhalb der Zelle sind, stellt die intrazelluläre Abgabe von Mitteln eine große Herausforderung. Häufig werden Drogen, insbesondere Biologika, durch Zellen internalisiert und gehandelte zu Vesikeln, dass entweder eine Verschlechterung ihres Inhalts durch die Endo-lysosomalen Weg führen, oder zurück aus der Zelle über pendelte Exozytose. 1 Bei letzterem Verfahren, das interne pH der Vesikel auf etwa 5-6 angesäuert, welches der optimale pH für die Aktivität von Enzymen, die Funktion in diesem Abteil, wie Lysozym. 2 In jüngster Zeit haben eine Reihe von Materialien speziell zu nutzen, die Versauerung der Endosomen, um cytosolische Lieferung von ihrer Ladung zu erleichtern entwickelt. Ein Beispiel für diesen Ansatz verwendet synthetische, Polymermizelle Nanopartikel, deren Kern im zwitterionischen und ladungsneutrale bei physiologischem pH (dh 7,4). Jedoch bei pH 6,0- 6.5, wobei die Polymere zu erwerben protoniert und eine positive Nettoladung, die die Micellkerns destabilisiert, und die freiliegenden Polymersegmente interagieren und stören die endosomale Membran. Diese Aktivität wurde gezeigt, dass die endosomalen Entweichen von Peptid und Nucleinsäure-Therapeutika zu fördern, so dass sie ihre Ziele cytosolischen übersetzen. 3,4 Andere Beispiele von Methoden entwickelt, die den Escape-endosomalen Membranbarriere stören vermitteln beinhalten &#39;fusogenen&#39; Peptide oder Proteine, die Membranfusion oder transiente Porenbildung in der Phospholipid-Doppelschicht vermitteln können. 5 Homopolymerisate von anionischen Alkylacrylsäuren wie Poly (Propylacrylsäure) sind eine weitere gut untersuchten Ansatz, und in diesen Polymeren, bestimmt der Protonierungsgrad von anhängenden Carbonsäure Übergangs in eine hydrophobe, Membran-disruptive Zustand in endo-lysosomalen pH-Bereiche. 6,7 Ein nützliches Modell für das Screening endosomolytischen Verhalten ist die ex vivo pH-abhängig Hämolyse-Assay. 8 In diesem Modellsystem dient die Erythrozytenmembran als Surrogat für die Lipid-Doppelschicht-Membran, die Endo-lysosomalen Vesikeln umschließen. Dieses Modell generalisierbar von anderen verwendet worden, um die endosomolytische Verhalten zellpenetrierendes Peptide und andere polymere Genabgabesysteme auszuwerten. 8-11 In diesem Experiment sind menschliche rote Blutzellen und Testmaterialien in Puffern bei pH-Werten definiert, die imitieren coinkubiert extrazellulären (7,4), frühe Endosomen (6,8), und am späten endo-lysosomalen (&lt;6,8) Umgebungen. Die Menge an Hämoglobin während der Inkubationszeit freigesetzt wird als Maß für die Lyse der roten Blutkörperchen, die der Menge an Hämoglobin im positiven Kontrollproben mit einem Detergens lysiert freigesetzt normalisiert wird quantifiziert. Von Screening einer kleinen Bibliothek von potenziell endosomolytischen Testmaterialien, kann man folgern, dass Proben, die keine Hämolyse produzieren bei pH 7,4, aber deutlich erhöhten Saumolysis bei pH &lt;6,5, werden die effektivsten und cytocompatible Kandidaten für cytosolische Drug Delivery sein. Materialien, die diese Kriterien erfüllen würde voraussichtlich nicht inert und nicht wahllos zerstören Lipiddoppelschichtmembranen (dh, die Zytotoxizität führen können) bis an einen Abfall der lokale pH-Wert nach Internalisierung in endo-lysosomaler Kompartimente ausgesetzt werden. In diesem Protokoll werden Erythrozyten von einem menschlichen Spender isoliert und bei pH 5,6, 6,2, 6,8 oder 7,4 mit experimentellen endosomolytische Arzneimittelabgabe Mittel co-inkubiert. Intakte Erythrozyten werden pelletiert, und die Überstände (enthaltend Hämoglobin aus lysierten Erythrozyten freigesetzt) ​​für die charakteristische Absorption von Hämoglobin über einen Plattenleser (Abbildung 1) analysiert.

<table border="1"><tr><td> Name des Reagenzes </td><td> Firma </td><td> Katalog-Nummer </td><td> Kommentare (optional) </td></tr><tr><td> BD Vacutainer - K2EDTA Vacutainer Tubes </td><td> Fisher Scientific </td><td> 22-253-145 </td><td> Für die Blutentnahme </td></tr><tr><td> BD Vacutainer Blutentnahmekanülen, 20,5-Gauge </td><td> Fisher Scientific </td><td> 02-665-31 </td><td> Für die Blutentnahme </td></tr><tr><td> BD Vacutainer Tube Holder / Needle Adapter </td><td> Fisher Scientific </td><td> 22-289-953 </td><td> Für die Blutentnahme </td></tr><tr><td> BD Marke Isopropylalkohol Swabs </td><td> Fisher Scientific </td><td> 13-680-63 </td><td> Für die Blutentnahme </td></tr><tr><td> BD Vacutainer Latex-Free Tourniquet </td><td> Fisher Scientific </td><td> 02-657-6 </td><td> Für die Blutentnahme </td&gt; </tr><tr><td> Salzsäure (konz.) </td><td> Fisher Scientific </td><td> A144-500 </td><td> Zur Einstellung des pH der D-PBS. </td></tr><tr><td> Triton X-100 </td><td> Sigma-Aldrich </td><td> T8787 </td><td> Positive Kontrolle </td></tr><tr><td> Dulbecco PBS </td><td> Invitrogen </td><td> 14190 </td><td></td></tr><tr><td> Nalgene MF75 Sterile Bottle-Top-Filter-Einheit mit SFCA Membrane </td><td> Fisher Scientific </td><td> 09-740-44A </td><td></td></tr><tr><td> BD 96-Well-Platten mit flachem Boden, Gewebekultur-behandelten Polystyrol </td><td> Fisher Scientific </td><td> 08-772-2C </td><td> Für plattenförmige Lesung am Ende des Assays. </td></tr><tr><td> BD 96-Well-Platten, mit rundem Boden, Gewebekultur-behandelten Polystyrol </td><td> Fisher Scientific </td><td> 08-772-17 </td><td> Für die Inkubation von roten Blutkörperchen mit den experimentellen Mitteln. </td></tr></table&gt;

ex vivo red blood cell hemolysis assay for the evaluation of ph-responsive endosomolytic agents for cytosolic delivery of biomacromolecular drugs

Phospholipiddoppelschichten die endo-lysosomalen Vesikeln bilden eine Barriere, die Lieferung von biologischen Medikamenten zur intrazellulären Ziele darstellen. Um diese Barriere zu überwinden, wurde eine Reihe von synthetischen Droge Trägern entwickelt worden, um aktiv zu stören den endosomalen Membran und liefern Fracht in das Zytoplasma. Hier beschreiben wir die Hämolyse Assay, der als rasche, Hochdurchsatz-Bildschirm für den cytocompatibility und endosomolytische Aktivität der intrazellulären Drug Delivery Systemen verwendet werden können. In der Hämolyse Assay werden menschlichen roten Blutkörperchen und Testmaterialien in Puffern bei pH-Werten definiert, die extrazelluläre, frühe endosomalen und lysosomalen späten Endo-Umgebungen imitieren coinkubiert. Nach einem Zentrifugationsschritt zu pelletieren intakten roten Blutzellen, wird die Menge des Hämoglobins in das Medium freigesetzt spektrophotometrisch gemessen (405 nm für die besten Dynamikbereich). Der prozentuale Anteil der roten Blutkörperchen Störung wird dann quantifiziert, bezogen auf positive Kontrolle samples lysiert mit einem Reinigungsmittel. In diesem Modellsystem die Erythrozytenmembran dient als Surrogat für die Lipid-Doppelschicht Membran, die Endo-lysosomalen Vesikeln umschließen. Das gewünschte Ergebnis ist vernachlässigbar Hämolyse bei physiologischem pH (7,4) und robuste Hämolyse in der endo-lysosomalen pH-Bereich von etwa pH 5 bis 6,8.

<html> Typischerweise weisen die Mittel, die idealen pH-abhängigen hämolytischen Verhalten zeigen das höchste Potenzial für cytosolische Abgabe von Medikamenten, Nukleinsäuren oder anderen bioaktiven Molekülen. Dies wird durch Agent # 1 beispielhaft dargestellt, wie in Abbildung 2, die minimale Hämolyse bei pH 7,4 zeigt dargestellt, aber ein starker Anstieg der hämolytischen Verhalten bei endosomalen pH-Bereichen (&lt;6.5). Einige Mittel können ein erhebliches Maß an hämolytisch Verhalten bei ...

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Ex Vivo Red Blood Cell Hemolysis Assay for the Evaluation of pH-responsive Endosomolytic Agents for Cytosolic Delivery of Biomacromolecular Drugs

Eine Hämolyse-Assay kann als schnelle, Hochdurchsatz-Screening von Drug-Delivery-Systeme &quot;cytocompatibility und endosomolytische Aktivität für die intrazelluläre Frachtlieferungen verwendet werden. Der Assay misst die Unterbrechung der Erythrozytenmembranen als Funktion der pH Wert.

Ex Vivo Red Blood Cell Hämolyse-Assay für die Beurteilung von pH-responsive endosomolytischen Agenten für Cytosolic Lieferung von Biomakromoleülkomplexen Drugs

Phospholipid bilayers that constitute endo-lysosomal vesicles can pose a barrier to delivery of biologic drugs to intracellular targets. To overcome this ...

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Research

JoVE Journal

Immunology and Infection

Ex Vivo Red Blood Cell Hemolysis Assay for the Evaluation of pH-responsive Endosomolytic Agents for Cytosolic Delivery of Biomacromolecular Drugs

34.0K Aufrufe.  Vanderbilt University. Eine Hämolyse-Assay kann als schnelle, Hochdurchsatz-Screening von Drug-Delivery-Systeme "cytocompatibility und endosomolytische Aktivität für die intrazelluläre Frachtlieferungen verwendet werden. Der Assay misst die Unterbrechung der Erythrozytenmembranen als Funktion der pH Wert.

Serie: Ex Vivo Red Blood Cell Hemolysis Assay for the Evaluation of pH-responsive Endosomolytic Agents for Cytosolic Delivery of Biomacromolecular Drugs

Introducing Shear Stress in the Study of Bacterial Adhesion

During bacterial infections a sequence of interactions occur between the pathogen and its host. Bacterial adhesion to the host cell surface is often the initial and determining step of the pathogenesis. Although experimentally adhesion is mostly studied in static conditions adhesion actually takes place in the presence of flowing liquid. First encounters between bacteria and their host often occur at the mucosal level, mouth, lung, gut, eye, etc. where mucus flows along the surface of epithelial cells. Later in infection, pathogens occasionally access the blood circulation causing life-threatening illnesses such as septicemia, sepsis and meningitis. A defining feature of these infections is the ability of these pathogens to interact with endothelial cells in presence of circulating blood. The presence of flowing liquid, mucus or blood for instance, determines adhesion because it generates a mechanical force on the pathogen. To characterize the effect of flowing liquid one usually refers to the notion of shear stress, which is the tangential force exerted per unit area by a fluid moving near a stationary wall, expressed in dynes/cm2. Intensities of shear stress vary widely according to the different vessels type, size, organ, location etc. (0-100 dynes/cm2). Circulation in capillaries can reach very low shear stress values and even temporarily stop during periods ranging between a few seconds to several minutes 1. On the other end of the spectrum shear stress in arterioles can reach 100 dynes/cm2 2. The impact of shear stress on different biological processes has been clearly demonstrated as for instance during the interaction of leukocytes with the endothelium 3. To take into account this mechanical parameter in the process of bacterial adhesion we took advantage of an experimental procedure based on the use of a disposable flow chamber 4. Host cells are grown in the flow chamber and fluorescent bacteria are introduced in the flow controlled by a syringe pump. We initially focused our investigations on the bacterial pathogen Neisseria meningitidis, a Gram-negative bacterium responsible for septicemia and meningitis. The procedure described here allowed us to study the impact of shear stress on the ability of the bacteria to: adhere to cells 1, to proliferate on the cell surface 5and to detach to colonize new sites 6 (Figure 1). Complementary technical information can be found in reference 7. Shear stress values presented here were chosen based on our previous experience1 and to represent values found in the literature. The protocol should be applicable to a wide range of pathogens with specific adjustments depending on the objectives of the study.

During the infection process, a key step is the adhesion of pathogens with host cells. In most instances this adhesion step occurs in the presence of mechanical stress generated by flowing liquid. We describe a technique that introduces shear stress as an important parameter in the study of bacterial adhesion.

Introducing Schubspannung in der Studie der bakteriellen Adhäsion

During bacterial infections a sequence of interactions occur between the pathogen and its host. Bacterial adhesion to the host cell surface is often the ...

Forschung

Immunologie und Infektion

A Quantitative Evaluation of Cell Migration by the Phagokinetic Track Motility Assay

Cellular motility is an important biological process for both unicellular and multicellular organisms. It is essential for movement of unicellular organisms towards a source of nutrients or away from unsuitable conditions, as well as in multicellular organisms for tissue development, immune surveillance and wound healing, just to mention a few roles1,2,3. Deregulation of this process can lead to serious neurological, cardiovascular and immunological diseases, as well as exacerbated tumor formation and spread4,5. Molecularly, actin polymerization and receptor recycling have been shown to play important roles in creating cellular extensions (lamellipodia), that drive the forward movement of the cell6,7,8. However, many biological questions about cell migration remain unanswered.
The central role for cellular motility in human health and disease underlines the importance of understanding the specific mechanisms involved in this process and makes accurate methods for evaluating cell motility particularly important. Microscopes are usually used to visualize the movement of cells. However, cells move rather slowly, making the quantitative measurement of cell migration a resource-consuming process requiring expensive cameras and software to create quantitative time-lapsed movies of motile cells. Therefore, the ability to perform a quantitative measurement of cell migration that is cost-effective, non-laborious, and that utilizes common laboratory equipment is a great need for many researchers.
The phagokinetic track motility assay utilizes the ability of a moving cell to clear gold particles from its path to create a measurable track on a colloidal gold-coated glass coverslip9,10. With the use of freely available software, multiple tracks can be evaluated for each treatment to accomplish statistical requirements. The assay can be utilized to assess motility of many cell types, such as cancer cells11,12, fibroblasts9, neutrophils13, skeletal muscle cells14, keratinocytes15, trophoblasts16, endothelial cells17, and monocytes10,18-22. The protocol involves the creation of slides coated with gold nanoparticles (Au&deg;) that are generated by a reduction of chloroauric acid (Au3+) by sodium citrate. This method was developed by Turkevich et al. in 195123 and then improved in the 1970s by Frens et al.24,25. As a result of this chemical reduction step, gold particles (10-20 nm in diameter) precipitate from the reaction mixture and can be applied to glass coverslips, which are then ready for use in cellular migration analyses9,26,27.
In general, the phagokinetic track motility assay is a quick, quantitative and easy measure of cellular motility. In addition, it can be utilized as a simple high-throughput assay, for use with cell types that are not amenable to time-lapsed imaging, as well as other uses depending on the needs of the researcher. Together, the ability to quantitatively measure cellular motility of multiple cell types without the need for expensive microscopes and software, along with the use of common laboratory equipment and chemicals, make the phagokinetic track motility assay a solid choice for scientists with an interest in understanding cellular motility.

The phagokinetic motility track assay is a method used to assess the movement of cells. Specifically, the assay measures chemokinesis (random cell motility) over time in a quantitative manner. The assay takes advantage of the ability of cells to create a measurable track of their movement on colloidal gold-coated coverslips.

Eine quantitative Auswertung der Zellmigration durch die Phagokinetic Spur Motilität Assay

Cellular motility is an important biological process for both unicellular and multicellular organisms. It is essential for movement of unicellular ...

Antigens Protected Functional Red Blood Cells By The Membrane Grafting Of Compact Hyperbranched Polyglycerols

Red blood cell (RBC) transfusion is vital for the treatment of a number of acute and chronic medical problems such as thalassemia major and sickle cell anemia 1-3. Due to the presence of multitude of antigens on the RBC surface (~308 known antigens 4), patients in the chronic blood transfusion therapy develop alloantibodies due to the miss match of minor antigens on transfused RBCs 4, 5. Grafting of hydrophilic polymers such as polyethylene glycol (PEG) and hyperbranched polyglycerol (HPG) forms an exclusion layer on RBC membrane that prevents the interaction of antibodies with surface antigens without affecting the passage of small molecules such as oxygen ,glucose, and ions3. At present no method is available for the generation of universal red blood donor cells in part because of the daunting challenge presented by the presence of large number of antigens (protein and carbohydrate based) on the RBC surface and the development of such methods will significantly improve transfusion safety, and dramatically improve the availability and use of RBCs. In this report, the experiments that are used to develop antigen protected functional RBCs by the membrane grafting of HPG and their characterization are presented. HPGs are highly biocompatible compact polymers 6, 7, and are expected to be located within the cell glycocalyx that surrounds the lipid membrane 8, 9 and mask RBC surface antigens10, 11.

The cell membrane modification of red blood cells (RBCs) with hyperbranched polyglycerol (HPG) is presented. Modified RBCs were characterized by aqueous two phase partitioning, osmotic fragility and complement mediated lysis. The camouflage of surface proteins and antigens was evaluated using the flow cytometry and Micro Typing System (MTS) blood phenotyping cards.

Antigene geschützten funktionellen Red Blood Cells durch die Membran Pfropfung von Compact hyperverzweigten Polyglycerinen

Red blood cell (RBC) transfusion is vital for the treatment of a number of acute and chronic medical problems such as thalassemia major and sickle cell ...

Methods for Quantitative Detection of Antibody-induced Complement Activation on Red Blood Cells

Antibodies against red blood cells (RBCs) can lead to complement activation resulting in an accelerated clearance via complement receptors in the liver (extravascular hemolysis) or leading to intravascular lysis of RBCs. Alloantibodies (e.g. ABO) or autoantibodies to RBC antigens (as seen in autoimmune hemolytic anemia, AIHA) leading to complement activation are potentially harmful and can be - especially when leading to intravascular lysis - fatal1. Currently, complement activation due to (auto)-antibodies on RBCs is assessed in vitro by using the Coombs test reflecting complement deposition on RBC or by a nonquantitative hemolytic assay reflecting RBC lysis1-4. However, to assess the efficacy of complement inhibitors, it is mandatory to have quantitative techniques. Here we describe two such techniques. First, an assay to detect C3 and C4 deposition on red blood cells that is induced by antibodies in patient serum is presented. For this, FACS analysis is used with fluorescently labeled anti-C3 or anti-C4 antibodies. Next, a quantitative hemolytic assay is described. In this assay, complement-mediated hemolysis induced by patient serum is measured making use of spectrophotometric&#160;detection of the released hemoglobin. Both of these assays are very reproducible and quantitative, facilitating studies of antibody-induced complement activation.

Here we describe two assays for measuring complement activation induced by antibodies against red blood cells. The major advantage over the current assays is their quantitative and easy-to-interpret nature.

Methoden für die quantitative Bestimmung von Antikörper-induzierte Komplementaktivierung auf Red Blood Cells

Antibodies against red blood cells (RBCs) can lead to complement activation resulting in an accelerated clearance via complement receptors in the liver ...

High-throughput Quantitative Real-time RT-PCR Assay for Determining Expression Profiles of Types I and III Interferon Subtypes

Described in this report is a qRT-PCR assay for the analysis of seventeen human IFN subtypes in a 384-well plate format that incorporates highly specific locked nucleic acid (LNA) and molecular beacon (MB) probes, transcript standards, automated multichannel pipetting, and plate drying. Determining expression among the type I interferons (IFN), especially the twelve IFN-&#945; subtypes, is limited by their shared sequence identity; likewise, the sequences of the type III IFN, especially IFN-&#955;2 and -&#955;3, are highly similar. This assay provides a reliable, reproducible, and relatively inexpensive means to analyze the expression of the seventeen interferon subtype transcripts.

This protocol describes a high-throughput qRT-PCR assay for the analysis of type I and III IFN expression signatures. The assay discriminates single base pair differences between the highly similar transcripts of these genes. Through batch assembly and robotic pipetting, the assays are consistent and reproducible.

Hochdurchsatz-quantitative Echtzeit-RT-PCR-Assay zur Bestimmung Expressionsprofile der Typen I und III Interferon-Formationsglieder

Described in this report is a qRT-PCR assay for the analysis of seventeen human IFN subtypes in a 384-well plate format that incorporates highly specific ...

Use of a Monocyte Monolayer Assay to Evaluate Fc&#947; Receptor-mediated Phagocytosis

Although originally developed for predicting transfusion outcomes of serologically incompatible blood, the monocyte monolayer assay (MMA) is a highly versatile in vitro assay that can be modified to examine different aspects of antibody and Fc&#947; receptor (Fc&#947;R)-mediated phagocytosis in both research and clinical settings. The assay utilizes adherent monocytes from peripheral blood mononuclear cells isolated from mammalian whole blood. MMA has been described for use in both human and murine investigations. These monocytes express Fc&#947;Rs (e.g., Fc&#947;RI, Fc&#947;RIIA, Fc&#947;RIIB, and Fc&#947;RIIIA) that are involved in immune responses. The MMA exploits the mechanism of Fc&#947;R-mediated interactions, phagocytosis in particular, where antibody-sensitized red blood cells (RBCs) adhere to and/or activate Fc&#947;Rs and are subsequently phagocytosed by the monocytes. In vivo, primarily tissue macrophages found in the spleen and liver carry out Fc&#947;R-mediated phagocytosis of antibody-opsonized RBCs, causing extravascular hemolysis. By evaluating the level of phagocytosis using the MMA, different aspects of the in vivo Fc&#947;R-mediated process can be investigated. Some applications of the MMA include predicting the clinical relevance of allo- or autoantibodies in a transfusion setting, assessing candidate drugs that promote or inhibit phagocytosis, and combining the assay with fluorescent microscopy or traditional Western immunoblotting to investigate the downstream signaling effects of Fc&#947;R-engaging drugs or antibodies. Some limitations include the laboriousness of this technique, which takes a full day from start to finish, and the requirement of research ethics approval in order to work with mammalian blood. However, with diligence and adequate training, the MMA results can be obtained within a 24-h turnover time.

Use of a Monocyte Monolayer Assay to Evaluate Fc&amp;#947; Receptor-mediated Phagocytosis

The monocyte monolayer assay (MMA) is an in vitro assay that utilizes isolated primary monocytes obtained from mammalian peripheral whole blood to evaluate Fc&#947; receptor (Fc&#947;R)-mediated phagocytosis.

Die Verwendung eines Monozyten einschichtiges Assay Fcy rezeptorvermittelte Phagozytose zur Bewertung

Although originally developed for predicting transfusion outcomes of serologically incompatible blood, the monocyte monolayer assay (MMA) is a highly ...

Dextran Enhances the Lentiviral Transduction Efficiency of Murine and Human Primary NK Cells

The efficient transduction of specific genes into natural killer (NK) cells has been a major challenge. Successful transductions are critical to defining the role of the gene of interest in the development, differentiation, and function of NK cells. Recent advances related to chimeric antigen receptors (CARs) in cancer immunotherapy accentuate the need for an efficient method to deliver exogenous genes to effector lymphocytes. The efficiencies of lentiviral-mediated gene transductions into primary human or mouse NK cells remain significantly low, which is a major limiting factor. Recent advances using cationic polymers, such as polybrene, show an improved gene transduction efficiency in T cells. However, these products failed to improve the transduction efficiencies of NK cells. This work shows that dextran, a branched glucan polysaccharide, significantly improves the transduction efficiency of human and mouse primary NK cells. This highly reproducible transduction methodology provides a competent tool for transducing human primary NK cells, which can vastly improve clinical gene delivery applications and thus NK cell-based cancer immunotherapy.

The goal of this study was to formulate technologies that allow for successful gene transduction in primary natural killer (NK) cells. The dextran-mediated lentiviral transduction of human or mouse primary NK cells results in higher gene expression efficiencies. This method of gene transduction will vastly improve NK cell genetic manipulation.

Dextran erhöht die Effizienz der Lentivirale Transduktion von murinen und menschliche primäre NK-Zellen

The efficient transduction of specific genes into natural killer (NK) cells has been a major challenge. Successful transductions are critical to defining ...

A Simple Red Blood Cell Lysis Method for the Establishment of B Lymphoblastoid Cell Lines

A number of methods exist for the transformation of B lymphocytes by the Epstein Barr virus in vitro into immortalized cell lines. We have developed a new method with a powerful and simple strategy for the establishment of B-LCLs, the red blood cell lysis method. This method simplified the PBMC separation procedure with red blood cell removal, and used as little as 0.5 mL of whole blood for establishing EBV-immortalized cell lines, which can proliferate to large cell numbers in a relatively short amount time with a 100% success rate. The method is simple, reliable, time saving, and applicable to treating a large number of the clinical samples.

A simple red blood cell lysis method for establishing B-LCLs was developed with high immortalization efficiency, requiring a small amount of blood and saving time from initiation to cryopreservation.

A Simple Red Blood Cell Lysis Verfahren zur Etablierung von B Lymphoblastoidzelllinien

A number of methods exist for the transformation of B lymphocytes by the Epstein Barr virus in vitro into immortalized cell lines. We have developed a new ...

In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model

Current methodologies for antigen-specific killing are limited to in vitro use or utilized in infectious disease models. However, there is not a protocol specifically intended to measure antigen-specific killing without an infection. This protocol is designed and describes methods to overcome these limitations by allowing for the detection of antigen-specific killing of a target cell by CD8+ T cells in vivo. This is accomplished by merging a vaccination model with a traditional CFSE-labeled target killing assay. This combination allows the researcher to assess the antigen-specific CTL potential directly and quickly as the assay is not dependent upon tumor growth or infection. In addition, the readout is based on flow cytometry and so should be readily accessible to most researchers. The major limitation of the study is identifying the timeline in vivo that is appropriate to the hypothesis being tested. Variations in antigen strength and mutations in the T cells that may result in differential cytolytic function need to be carefully assessed to determine the optimal time for cell harvest and assessment. The appropriate concentration of peptide for vaccination has been optimized for hgp10025-33 and OVA257-264, but further validation would be needed for other peptides that may be more appropriate to a given study. Overall, this protocol allows a quick assessment of killing function in vivo and can be adapted to any given antigen.

In Vivo Assay for Detection of Antigen-specific T-cell Cytolytic Function Using a Vaccination Model

The goal of this protocol is to allow for detection of in vivo antigen-specific killing of a target cell in a murine model.

In Vivo Test zum Nachweis von Antigen-spezifischen T-Zell Zytolyse-Funktion mit einer Impfung-Modell

Current methodologies for antigen-specific killing are limited to in vitro use or utilized in infectious disease models. However, there is not a protocol ...

Measuring Deformability and Red Cell Heterogeneity in Blood by Ektacytometry

Decreased red cell deformability is characteristic of several disorders. In some cases, the extent of defective deformability can predict severity of disease or occurrence of serious complications. Ektacytometry uses laser diffraction viscometry to measure the deformability of red blood cells subject to either increasing shear stress or an osmotic gradient at a constant value of applied shear stress. However, direct deformability measurements are difficult to interpret when measuring heterogenous blood that is characterized by the presence of both rigid and deformable red cells. This is due to the inability of rigid cells to properly align in response to shear stress and results in a distorted diffraction pattern marked by an exaggerated decrease in apparent deformability. Measurement of the degree of distortion provides an indicator of the heterogeneity of the erythrocytes in blood. In sickle cell anemia, this is correlated with the percentage of rigid cells, which reflects the hemoglobin concentration and hemoglobin composition of the erythrocytes. In addition to measuring deformability, osmotic gradient ektacytometry provides information about the osmotic fragility and hydration status of erythrocytes. These parameters also reflect the hemoglobin composition of red blood cells from sickle cell patients. Ektacytometry measures deformability in populations of red cells and does not, therefore, provide information on the deformability or mechanical properties of individual erythrocytes. Regardless, the goal of the techniques described herein is to provide a convenient and reliable method for measuring the deformability and cellular heterogeneity of blood. These techniques may be useful for monitoring temporal changes, as well as disease progression and response to therapeutic intervention in several disorders. Sickle cell anemia is one well-characterized example. Other potential disorders where measurements of red cell deformability and/or heterogeneity are of interest include blood storage, diabetes, Plasmodium infection, iron deficiency, and the hemolytic anemias due to membrane defects.

Here we present techniques to measure red cell deformability and cellular heterogeneity by ektacytometry. These techniques are applicable to general investigations of red cell deformability and specific investigations of blood diseases characterized by the presence of both rigid and deformable red cells in circulation, such as sickle cell anemia.

Messung der Verformbarkeit und Heterogenität der Erythrozyten im Blut durch Ektacytometry

Decreased red cell deformability is characteristic of several disorders. In some cases, the extent of defective deformability can predict severity of ...