Name: laminar flow-based assays to investigate leukocyte recruitment on cultured vascular cells and adherent platelets
Uploaded: 2018-04-09T15:00:00
Description: Watch this Scientific Journal Video about Laminar Flow-based Assays to Investigate Leukocyte Recruitment on Cultured Vascular Cells and Adherent Platelets at JoVE.com

Vi takker Drs. Martin M. Schmitt og linje Fraemohs. Dette arbejde blev støttet af det nederlandske Institut for videnskabelig forskning (ZonMW VIDI 016.126.358, Landsteiner Foundation for blodtransfusion forskning (LSBR Nr. 1638) og Deutsche Forschungsgemeinschaft (SFB1123/A2) tildeles R.R.K.

Alle metoder beskrevet her er blevet godkendt af den medicinske etiske og dyr etiske nævn af Maastricht Universitet.
1. flow-baseret analyse med humane celler
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Isolering af trombocytter fra humant blod
	<ol>
<li>Trække venøse blod i citrat (3,2%) antikoagulans.</li>
		<li>Tilføj 1/15 bind af syre citrat Dextrose (ACD: 80 mM Trinatriumcitrat, 52 mM citronsyre og 183 mM glukose) til blodet.</li>
		<li>Der centrifugeres ved 350 x g uden bremse for 15 min at få blod...

<ol>
	<li>Dinauer, M. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+immune+deficiencies+with+defects+in+neutrophil+function.">Primary immune deficiencies with defects in neutrophil function.</a> American Society of Hematology. 2016 (1), 43-50 (2016).</li><li>Butcher, E. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leukocyte-endothelial+cell+recognition:+three+(or+more)+steps+to+specificity+and+diversity.">Leukocyte-endothelial cell recognition: three (or more) steps to specificity and diversity.</a> Cell. 67 (6), 1033-1036 (1991).</li><li>Springer, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Traffic+signals+for+lymphocyte+recirculation+and+leukocyte+emigration:+the+multistep+paradigm.">Traffic signals for lymphocyte recirculation and leukocyte emigration: the multistep paradigm.</a> Cell. 76 (2), 301-314 (1994).</li><li>Nourshargh, S., Alon, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leukocyte+migration+into+inflamed+tissues.">Leukocyte migration into inflamed tissues.</a> Immunity. 41 (5), 694-707 (2014).</li><li>Legein, B., Temmerman, L., Biessen, E. A. L., Lutgens, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammation+and+immune+system+interactions+in+atherosclerosis.">Inflammation and immune system interactions in atherosclerosis.</a> Cellular and Molecular Life Sciences. 70 (20), 3847-3869 (2013).</li><li>Wang, Y., Sakuma, M., 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=Leukocyte+engagement+of+platelet+glycoprotein+Ibalpha+via+the+integrin+Mac-1+is+critical+for+the+biological+response+to+vascular+injury.">Leukocyte engagement of platelet glycoprotein Ibalpha via the integrin Mac-1 is critical for the biological response to vascular injury.</a> Circulation. 112 (19), 2993-3000 (2005).</li><li>Zhao, Z., Vajen, T., 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=Deletion+of+junctional+adhesion+molecule+A+from+platelets+increases+early-stage+neointima+formation+after+wire+injury+in+hyperlipidemic+mice.">Deletion of junctional adhesion molecule A from platelets increases early-stage neointima formation after wire injury in hyperlipidemic mice.</a> Journal of cellular and molecular medicine. , (2017).</li><li>Wang, Y., Gao, H., 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=Leukocyte+integrin+Mac-1+regulates+thrombosis+via+interaction+with+platelet+GPIb&#945;.">Leukocyte integrin Mac-1 regulates thrombosis via interaction with platelet GPIb&#945;.</a> Nature communications. 8, 15559 (2017).</li><li>Fujii, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PDMS-based+microfluidic+devices+for+biomedical+applications.">PDMS-based microfluidic devices for biomedical applications.</a> Microelectronic Engineering. 61-62, 907-914 (2002).</li><li>Son, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+shear+viscosity+and+shear+rate+from+pressure+drop+and+flow+rate+relationship+in+a+rectangular+channel.">Determination of shear viscosity and shear rate from pressure drop and flow rate relationship in a rectangular channel.</a> Polymer. 48 (2), 632-637 (2007).</li><li>Brinkmann, V., Laube, B., Abu Abed, U., Goosmann, C., Zychlinsky, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neutrophil+extracellular+traps:+how+to+generate+and+visualize+them.">Neutrophil extracellular traps: how to generate and visualize them.</a> Journal of visualized experiments : JoVE. (36), e1724 (2010).</li><li>Swamydas, M., Lionakis, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation,+purification+and+labeling+of+mouse+bone+marrow+neutrophils+for+functional+studies+and+adoptive+transfer+experiments.">Isolation, purification and labeling of mouse bone marrow neutrophils for functional studies and adoptive transfer experiments.</a> Journal of visualized experiments : JoVE. (77), e50586 (2013).</li><li>Schmitt, M. M. N., Megens, R. T. 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Denne i vitro assay er en enkel metode til at undersøge underliggende mekanismer af leukocyt rekruttering under vaskulære betændelse, men der er nogle kritiske punkter skal bemærkes. Det første krav til udført dette assay er perfusion af leukocytter løbet en intakt og Konfluerende vaskulære eller trombocyttal éncellelag. Dette kan opnås ved forudgående belægning af overflader med kollagen type jeg. Generelt, når du arbejder med primære vaskulære celler, er det vigtigt at forsigtigt løsne celler v...

Skade, betændelse eller infektion svare leukocytter hurtigt til patogen - eller skade-associeret molekylære mønstre (PAMPs, DAMPs), ændre i en aktiveret tilstand, og flytte ud af blodet til lokaliteter af betændelse og vævsskader. Leukocytter evne til at interagere med deres cellulære og molekylære miljø er afgørende for deres korrekte funktion som immunceller, som fremhævet af genetiske sygdomme såsom leukocyt adhæsion mangel1. Leukocyt adhæsion har været genstand for intense undersøgelser i løbet af de seneste årtier, og dette har resulteret i begrebet leukocyt adhæsion kaskade i de tidlige 1990s2,3. Leukocyt adhæsion initieres selectin-medieret tilfangetagelsen af leukocytter til endotelet, forårsager celler til at rulle over den vaskulære overflade. Denne rullende gør det muligt for leukocytter at scanne for endotel-bundet vandrende stikord, fx, kemokiner, som inducerer aktivering af integriner. Efterfølgende, mægle de aktiverede integriner binding til endotel ligander, hvilket resulterer i fast leukocyt anholdelse. Leukocytter kan efterfølgende forberede extravasate af gennemgang og breder sig, før gennemtrængende i endothelial éncellelag og transmigrating i det underliggende væv. Det grundlæggende koncept for den kanoniske leukocyt kaskade har stort set uændret siden introduktionen, tilsat nogle mellemliggende trin4. Ikke desto mindre, de præcise molekylære mekanismer og roller for de mange aktører involveret i leukocyt rekruttering er ikke klarlagt hidtil, og leukocyt rekruttering forbliver et vigtigt emne i feltet af infektion, inflammation, og (auto) immun forskning.
For eksempel steg vaskulære inflammatoriske sygdomme som åreforkalkning, leukocyt rekruttering til fartøj væg drev plaque udvikling. Ustabile aterosklerotisk plaque kan briste, hvilket fører til massive aktivering af trombocytter og koagulation system, og efterfølgende okklusion af fartøjet5. Dette kan resultere i alvorlige kardiovaskulære udfald som myokardieinfarkt eller slagtilfælde. Derudover endotel denudation som det opstår klinisk, fx efter stent i en koronararterie, fører til et væld af samspillet af leukocytter og trombocytter til udsatte fartøj væg interiør (f.eks.matrix komponenter og glat muskel celler) og af leukocytter med blodplader dækker den vaskulære skade. Disse interaktioner er vigtigt for den videre udvikling af sygdommen som monocyt-trombocyttal interaktioner kan drive neointima dannelse6,7. Derudover trombocyt-leukocyt interaktioner medieret af leukocyt integrin Mac-1 (αMβ2) og trombocyttal GPIbα er for nylig blevet identificeret som roman drivere for trombose hos mus8.
Givet den bred tilgængelighed af menneskers og dyrs blod som en kilde af leukocytter og trombocytter for forskning, og det brede spektrum af isolerede matrix molekyler og udødeliggjort cellelinjer leukocyt og vaskulær oprindelse, er det muligt at simulere leukocyt interaktioner under flow i et laboratorium indstilling, ved hjælp af specialdesignede flow perfusion kamre. Mange varianter har udformet i de seneste årtier, lige fra vakuum-drevet til selvklæbende perfusion kamre. Alle varianter har til fælles, den immobile del (f.eks., kulturperler vaskulære celler eller matrix proteiner) er samlet i et større lækagesikre kammer udstyret med en pre-defineret kanal aktivering perfusion af væsker over den immobile del. Derudover aktiveret forskud i molding teknologi udvikling af skræddersyede løsninger baseret på silica polymerer9. Viskositet og strømningshastigheden af de perfused væske og højden af kanalen bestemmer hovedsagelig shear stress Karakteristik af flow perfusion enhed10. I denne artikel præsenterer vi en in vitro- metode til at studere underliggende mekanismer af vedhæftning, nedtrapning vedhæftning og transmigration af leukocytter under venøse og arterielle flow regimer. Fordelen ved de metoder, der præsenteres her er at de kan udføres ved hjælp af en fælles kamera tilsluttet fluorescens mikroskop, og kræver ikke en eksperimentatorer til besidder høje tekniske færdigheder. I vitro assay kan manipuleres på mange måder (f.eks.ved at tilføje hæmmere eller blokere antistoffer), og er således gældende i forskellige modeller af vaskulære betændelse og giver mulighed for undersøgelse af adhæsion protein funktioner eller den evaluering af særlige forbindelser.

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			<td height="20" style="height:20px;width:420px;">Inverted fluorescence microscope e.g. EVOS-FL</td>
			<td style="width:189px;">Life Technologies Europe bv</td>
			<td style="width:163px;"></td>
			<td style="width:167px;"></td>
		</tr>
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			<td height="20" style="height:20px;width:420px;">Pump e.g. model: 210-CE</td>
			<td style="width:189px;">&#160;world precision instruments</td>
			<td style="width:163px;">78-9210W</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Falcon 35 mm TC-Treated Easy-Grip Style Cell Culture Dish</td>
			<td style="width:189px;">corning</td>
			<td style="width:163px;">353001</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">50 mL syringe</td>
			<td style="width:189px;">Becton Dickinson</td>
			<td style="width:163px;">300137</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Silicone tubing&#160;</td>
			<td style="width:189px;">VWR</td>
			<td style="width:163px;">228-0700</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Elbow Luer Connector Male</td>
			<td style="width:189px;">Ibidi</td>
			<td style="width:163px;">10802</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Female Luer Lock Coupler</td>
			<td style="width:189px;">Ibidi</td>
			<td style="width:163px;">10823</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Flow chamber</td>
			<td style="width:189px;">University Hospital RWTH Aachen</td>
			<td style="width:163px;"></td>
			<td>Patent DE10328277A1: Baltus T, Dautzenberg R, Weber CPD. Str&#246;mungskammer zur in-vitro-Untersuchung von physiologischen Vorg&#228;ngen an Zelloberfl&#228;chen. 2005.&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Ibidi sticky slide VI 0.4</td>
			<td style="width:189px;">Ibidi</td>
			<td>80608</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Coverslips for sticky slides&#160;</td>
			<td style="width:189px;">Ibidi</td>
			<td>10812</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Collagen Type I, rat tail</td>
			<td>Life Technologies Europe bv</td>
			<td style="width:163px;">A1048301</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Recombinant Human TNF-&#945;</td>
			<td>Peprotech</td>
			<td>300-01A</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Thrombin Receptor Activator for Peptide 6 (TRAP - 6)</td>
			<td>Anaspec / Eurogentec</td>
			<td>24191</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">SYTO 13 green fluorescent nucleic acid stain</td>
			<td>Life Technologies Europe bv</td>
			<td>S7575</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Hanks&#8217; Balanced Salt Solution 10x</td>
			<td>Sigma-Aldrich Chemie</td>
			<td>H4641</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HEPES buffer solution 1M, liquid</td>
			<td>Life Technologies Europe bv</td>
			<td>15630049</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">BUMINATE Albumin, 25%&#160;</td>
			<td>Baxter</td>
			<td>60010</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Water for injection</td>
			<td style="width:189px;">B. Braun</td>
			<td style="width:163px;">3624315</td>
			<td></td>
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		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Calcium chloride dihydrate</td>
			<td style="width:189px;">Merck</td>
			<td style="width:163px;">102382&#160;</td>
			<td></td>
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		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Magnesium chloride hexahydrate&#160;</td>
			<td>Sigma-Aldrich Chemie</td>
			<td style="width:163px;">M2670</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Apyrase</td>
			<td>Sigma-Aldrich Chemie</td>
			<td>A6535</td>
			<td></td>
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			<td height="20" style="height:20px;width:420px;">Primary Human Umbilical Vein Endothelial Cells (HUVEC)</td>
			<td style="width:189px;">Promocell GmbH</td>
			<td>C-12203</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Endothelial Cell Growth Medium (Ready-to-use)</td>
			<td style="width:189px;">Promocell GmbH</td>
			<td>C-22010</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Primary Human Aortic Endothelial Cells (HAoEC)</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">&#160;PCS-100-011</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Vascular Cell Basal Medium&#160;</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">PCS-100-030</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Endothelial Cell Growth Kit-BBE</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">PCS-100-040</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Primary Human Aortic Smooth Muscle Cells (HAoSMC)</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">PCS-100-012</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Vascular Smooth Muscle Cell Growth Kit</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">PCS-100-042</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Human endothelial cell line, EA.hy926</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">CRL-2922</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Dulbecco&#39;s Modified Eagle&#39;s Medium (DMEM)</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">30-2002</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Mouse endothelial cell line, SV 40 transformed (SVEC4-10)</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">CRL-2181</td>
			<td></td>
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		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Human Monocytic cell line, THP-1</td>
			<td style="width:189px;">DSMZ</td>
			<td style="width:163px;">ACC-16</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">RPMI 1640 with Ultra-Glutamine</td>
			<td style="width:189px;">Lonza</td>
			<td>BE12-702F/U1</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Mouse monocyte/macrophage RAW264.7</td>
			<td style="width:189px;">ATCC</td>
			<td style="width:163px;">TIB-71</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:420px;">Dulbecco&#39;s Modified Eagle&#39;s Medium (DMEM), high glucose</td>
			<td style="width:189px;">Gibco</td>
			<td style="width:163px;">11965092</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:420px;">Accutase</td>
			<td style="width:189px;">Promocell GmbH</td>
			<td>C-41310</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:420px;">Percoll</td>
			<td style="width:189px;">Sigma-Aldrich Chemie</td>
			<td>P1644</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:420px;">Histopaque 1119</td>
			<td style="width:189px;">Sigma-Aldrich Chemie</td>
			<td>11191</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:420px;">10x PBS</td>
			<td style="width:189px;">Life Technologies Europe bv</td>
			<td style="width:163px;">14200075</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:420px;">BD&#160;Vacutainer Plastic Blood Collection Tubes with Sodium Heparin</td>
			<td style="width:189px;">Becton Dickinson</td>
			<td style="width:163px;">367876</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:420px;">VACUETTE TUBE 9 ml 9NC Coagulation sodium citrate 3.2%&#160;</td>
			<td style="width:189px;">Greiner Bio</td>
			<td style="width:163px;">455322</td>
			<td></td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:420px;">HCl/EtOH mixture (1.2 mol/L HCl and 50% ethanol) in water</td>
			<td style="width:189px;">Sigma-Aldrich Chemie</td>
			<td style="width:163px;">Prepare by mixing 0.3L HCl (4 mol/L) with 0.7L of 70% v/v ethanol in a fume hood</td>
			<td></td>
		</tr>
	</tbody>
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laminar flow-based assays to investigate leukocyte recruitment on cultured vascular cells and adherent platelets

Ansættelse af leukocytter efter skade eller betændelse til steder af skade eller vævsskade er blevet undersøgt i løbet af de seneste årtier og har resulteret i begrebet leukocyt adhæsion cascade. Men de præcise molekylære mekanismer involveret i leukocyt rekruttering har endnu ikke blevet fuldt ud identificeret. Da leukocyt rekruttering er stadig et vigtigt emne i feltet af infektion, inflammation og (auto-) immune forskning, præsenterer vi en enkel laminar flow-baseret analyse at studere underliggende mekanismer af vedhæftning, nedtrapning vedhæftning, og transmigration af leukocytter under venøse og arterielle flow regimer. In vitro- analysen kan bruges til at studere de molekylære mekanismer, der ligger til grund for interaktioner mellem leukocytter og deres cellulære partnere i forskellige modeller af vaskulære betændelse. Denne protokol beskriver en laminar flow-baseret analyse ved hjælp af en parallel-strømmen kammer og et omvendt fase kontrast mikroskop tilsluttet et kamera til at studere samspillet af leukocytter og endotelceller eller blodplader, som kan visualiseres og indspillede derefter analyseret offline. Endotelceller, blodplader eller leukocytter kan blive forbehandlet med hæmmere eller antistoffer til at bestemme rollen af specifikke molekyler under denne proces. Shear betingelser, dvs arteriel eller venøs shear stress, kan tilpasses nemt af viskositet og strømningshastigheden af de perfused væske og højden af kanalen.

Til studier i endothelial-leukocyt adhæsion, var fluorescently mærket THP-1 celler perfunderet over en TNFα - eller ikke-stimuleret endotel éncellelag for 2 min på 3 dyne/cm2. Det samlede antal vedhængende monocytic celler blev fastsat efter 2 min af perfusion af fanger 6 uafhængige felter over en periode på 2-6 min. De vedhængende celler blev kvantificeret i mindst 6 billeder taget med en omvendt fase kontrast/fluorescens mikroskop (fxEVOS-FL) via 10 X forst?...

Watch this Scientific Journal Video about Laminar Flow-based Assays to Investigate Leukocyte Recruitment on Cultured Vascular Cells and Adherent Platelets at JoVE.com

Laminar Flow-based Assays to Investigate Leukocyte Recruitment on Cultured Vascular Cells and Adherent Platelets

Laminar Flow-baseret Assays til at undersøge leukocyt ansættelse på kulturperler vaskulære celler og vedhængende blodplader

Leukocytter interagere begærligt med vaskulære celler og blodplader efter fartøjet væg skade eller under betændelse. Her, beskriver vi en ligetil laminar flow-baseret analyse for at karakterisere de molekylære mekanismer, der ligger til grund for interaktioner mellem leukocytter og deres cellulære partnere.

The recruitment of leukocytes upon injury or inflammation to sites of injury or tissue damage has been investigated during recent decades and has resulted ...

The overall goal of this experiment is to investigate the mechanisms behind the interactions of leukocytes to adherent vascular cells or platelets under flow conditions. This method can help answer key questions in the immunology field such as how leukocytes are recruited to sites of inflammation. The main advantage of this technique is that it's cost effective, user friendly, and allows the investigation of a great variety of experimental conditions.This method can provide insight into leukocyte adhesion. It can also be applied to other systems such as the adhesion of tumor cells to immobilized cells or substrates under flow conditions. Demonstrating the procedure will be Annemiek Dickhout, an engineer and a PhD student working in my laboratory.After obtaining blood samples, add 1/15th volume of acid citrate dextrose to the blood. Next, centrifuge the blood sample by setting the brakes off at 350 times g for 15 minutes to obtain platelet-rich plasma. Then transfer the supernatant obtained to a 15 milliliter conical tube and add 1/10th volume of acid citrate dextrose to it.Again, centrifuge the suspension by setting the brakes off at 1, 120 times g for 15 minutes to obtain platelet-poor plasma. Next, discard the supernatant. Next, carefully resuspend the platelet pellet in platelet buffer maintained at pH 6.6 using a Pasteur pipette with a wide bore.Then add 1/10th volume of acid citrate dextrose to it and gently mix it. Next, centrifuge the platelets at 1, 120 times g for 15 minutes to form the pellet. After the centrifugation is over, discard the supernatant and resuspend the platelets in one milliliter of platelet buffer maintained at pH 7.5.Then use an automated hematology analyzer to measure the platelet concentration in 1/10th dilution. Finally, adjust the cell count with platelet buffer maintained at pH 7.5. To secure the adherent platelets, immerse the glass coverslip in 1.2 molar 50%volume by volume of hydrochloric acid ethanol mixture.After immersing, wash the coverslip twice with ultrapure water. Then use nitrogen to dry the coverslip. Next, use 100 microliters of 30 micrograms per milliliter of rat collagen type one to pre-coat the glass coverslip.After coating the glass coverslip, incubate the coverslips at room temperature for 30 minutes. Then expel the collagen solution and wash the coverslip with phosphate buffered saline thrice. Next, use 1%bovine serum albumin in HEPES buffer to block the collagen coated coverslips for 30 minutes at room temperature.After 30 minutes, wash the coverslips and then dry them to mount in the perfusion chamber. After mounting the coverslips, keep the platelets ready. To immobilize the platelets, transfer 70 microliters of platelet suspension to a channel and incubate for 1-1/2 hours at 37 degrees Celsius and 5%carbon dioxide.Then replace the nonadherent platelets with blocking buffer for 30 minutes at room temperature. Use one micromolar of cell-permeant green fluorescence nucleic acid stain to fluorescently label the leukocytes. After labeling, incubate the leukocytes for 30 minutes at 37 degrees Celsius.Then centrifuge the cells at 300 times g for five minutes to pellet the cells. Resuspend in phosphate buffered saline to wash the cells. Then centrifuge the cells at 300 times g for five minutes.Based on the flow rate, suspend five milliliters of the cells in assay buffer. Then heat a water bath to maintain 37 degrees Celsius. Next, set aside a 50 milliliter perfusion syringe and install it on the syringe holder.Then set the pump on with draw mode with the pump volume at zero milliliter and diameter at 26.70 millimeter. Next, attach a Luer lock coupler to the syringe and connect the tubing with the elbow Luer connector to the Luer lock coupler. Then attach the free end of the tubing to the flow chamber.To adhere the leukocytes to the immobilized platelets, connect the microslide with the syringe. To perfuse the leukocytes and then adhere to a bed of vascular or platelet monolayer, attach a second tubing to a 50 milliliter conical tube containing the assay buffer and then fill the tubing using a one milliliter pipette. Once the tubing is filled, squeeze it and connect it to the flow chamber.Before perfusing the leukocytes, add three millimolar of calcium chloride and two millimolar of magnesium chloride to the cell suspension. Then incubate the cells at 37 degrees Celsius for five minutes. To remove possible air stuck in the chamber and in the tubing, perfuse with assay buffer before perfusing the cells.Next, squeeze the tubes to close the end and switch the tubing from the assay buffer to the cell suspension thereby preventing any trapped air bubbles within. For the first cells to arrive, perfuse the cells at appropriate flow rate and shear stress. Keep perfusing the cells, maintaining the flow rate and shear stress for two minutes.Then capture six images of the rolling and adherent cells between two to six minutes using a fluorescence microscope with 10X magnification connected to a digital camera. In this assay, adhesion of green fluorescently labeled THP1 cells with the endothelial cells was analyzed in the presence or absence of tumor necrosis vector alpha stimulation. The graph and the fluorescence images obtained show significant increase in THP1 cell arrest upon stimulating the endothelial cells with tumor necrosis vector alpha in comparison to the control.When recorded in time lapse, transendothelial migration of primary monocytes can be monitored over time. Next, adhesion of fluorescently labeled neutrophils with immobilized platelet monolayer in a flow chamber was analyzed in the presence or absence of TRAP-6 stimulation. The plot obtained shows a sharp increase in the adhesion of neutrophils to the TRAP-6 stimulated platelets in comparison to the control.Next, platelets were obtained from JAM-A deficient mice to study its adhesion with raw 264.7 mouse monocyte in the presence of surface receptor inhibitors. The graph and the fluorescence images obtained show significant decrease in the adhesion of the mouse monocytes with the platelets when compared to the control. Further, to study the adhesion of raw 264.7 cells with platelets, JAM-A positive and deficient mice were exposed to incremental increase of shear stress.From the graph, it's clear that the adhesion of raw 264.7 cells with platelets obtained from JAM-A deficient mice are more resistant to shear stress than JAM-A positive platelets. Once mastered, this technique can be done in one day if performed properly. While attempting this procedure, it is important to very gently wash your platelets during isolation so that your platelets do not become pre-activated or aggregated.It is also crucial to make sure that you don't have any air bubbles in your flow system because the system might get congested and to ensure a stable and even shear stress. Following this procedure, underlying mechanisms of leukocyte recruitment during vascular inflammation can be investigated.

Research

JoVE Journal

Immunology and Infection

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