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

Agradecemos os Drs Martin M. Schmitt e linha Fraemohs. Este trabalho foi financiado pela Fundação de Holanda para a investigação científica (ZonMW VIDI 016.126.358, Landsteiner Fundação para pesquisa de transfusão de sangue (LSBR n. º 1638) e Deutsche Forschungsgemeinschaft (SFB1123/A2) atribuído a R.R.K.

Todos os métodos descritos aqui foram aprovados pela ética médica e Animal placas de ética da Universidade de Maastricht.
1. baseado em fluxo de ensaio com células humanas
<ol><li>
Isolamento de plaquetas do sangue humano
	<ol>
<li>Tirar sangue venoso em anticoagulante citrato (3,2%).</li>
		<li>Adicionar 15/1 volume de ácido citrato Dextrose (ACD: citrato trissódico 80mm, ácido cítrico de 52mm e glicose 183 mM) para o sangue.</li>
		<li>Centrifugar a 350 g de x sem...

<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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Este ensaio em vitro é um método simples para investigar os mecanismos subjacentes de recrutamento de leucócitos durante a inflamação vascular, mas existem alguns pontos críticos a ser anotadas. O primeiro requisito para executar com êxito este ensaio é a perfusão de leucócitos sobre uma intacta e confluente vasculares ou monocamada de plaquetas. Isto pode ser conseguido pela prévia do revestimento das superfícies com colágeno tipo eu. Em geral, quando se trabalha com células vasculares primárias,...

Após lesão, inflamação ou infecção, leucócitos respondem rapidamente ao patógeno ou dano-associada molecular padrões (PAMPs, represas), mudar para um estado ativado e mover fora do fluxo de sangue para locais de inflamação e tecido danos. A capacidade dos leucócitos de interagir com seu ambiente celular e molecular é essencial para a sua correta função como células do sistema imunológico, como destacado por desordens genéticas, como a adesão de leucócitos deficiência1. Adesão de leucócitos tem sido objecto de intensa investigação durante as últimas décadas, e isto resultou no conceito de cascata de adesão de leucócitos no início da década de 1990,2,3. Adesão de leucócitos é iniciada pela captura selectina-mediada dos leucócitos ao endotélio, fazendo com que as células a rolar sobre a superfície vascular. Este rolamento permite leucócitos procurar pistas migratórias endotélio-limite, por exemplo, quimiocinas, que induzem a ativação das integrinas. Posteriormente, as integrinas activadas mediam a ligação a ligantes endoteliais, resultando na prisão de leucócitos firme. Leucócitos podem posteriormente Prepare-se para extravasate rastejando e espalhando-se, antes de penetrar a monocamada endotelial e reencarnando no tecido subjacente. O conceito básico da cascata canônico leucócito tem permaneceram praticamente inalteradas desde a sua introdução, com algumas etapas intermediárias adicionado4. No entanto, os mecanismos moleculares exatos e os papéis de muitos jogadores envolvidos no recrutamento de leucócitos não foram clarificados, até agora, e recrutamento de leucócitos continua a ser um tema importante no campo da infecção, inflamação e (auto-) imune pesquisa.
Por exemplo, durante doenças inflamatórias vasculares como aterosclerose, aumentou o recrutamento de leucócitos para o vaso parede drives placa desenvolvimento. Ateroma instável pode se romper, levando à enorme ativação de plaquetas e o sistema de coagulação e posteriormente à oclusão do vaso5. Isso pode resultar em graves resultados cardiovasculares como infarto do miocárdio ou acidente vascular cerebral. Além disso, por exemplo, após implante de stent de uma artéria coronária, desnudamento endotelial que ocorre clinicamente, conduz a uma infinidade de interações de leucócitos e plaquetas para o interior de parede vaso expostas (por exemplo, componentes de matriz e liso as células do músculo) e de leucócitos com plaquetas cobrindo a lesão vascular. Essas interações são importantes para o desenvolvimento da doença como interações monócito plaquetas podem conduzir neointima formação6,7. Além disso, as interações leucócito-plaquetas mediada por leucócitos integrina Mac-1 (M. α β2) e plaquetas GPIbα recentemente foram identificados como drivers de romance de trombose em ratos8.
Dada a ampla disponibilidade de sangue humano e animal como fonte de leucócitos e plaquetas para pesquisa e o amplo espectro de moléculas isoladas de matriz e linhas de célula imortalizado de origem vascular e leucócitos, é possível simular leucócitos interações sob fluxo em um laboratório de configuração, usando câmaras de perfusão de fluxo especialmente concebidos. Muitas variantes foram projetadas nas últimas décadas, variando de orientado a vácuo para câmaras de perfusão autoadesivo. Todas as variantes têm em comum que a parte imóvel (por exemplo, culturas de células vasculares ou proteínas da matriz) é montada em uma câmara de estanques maior equipada com um canal predefinido permitindo a perfusão dos fluidos sobre a parte do imóvel. Além disso, os avanços na tecnologia de moldagem permitiram o desenvolvimento de soluções sob medidas com base em polímeros de silicone9. A viscosidade e a taxa de fluxo do líquido perfundido e a altura do canal principalmente determinam as características de tensão de cisalhamento do fluxo da perfusão dispositivo10. Neste artigo, apresentamos uma in vitro método para estudar os mecanismos subjacentes da adesão, de adesão e transmigração de leucócitos sob regimes de fluxo arterial e venoso. A vantagem dos métodos apresentados aqui é que eles podem ser executados usando um microscópio de fluorescência conectado a câmera comum e não exigem um experimentadores possuir alta proficiência técnica. O ensaio em vitro podem ser manipulado de várias maneiras (por exemplo, adicionando inibidores ou bloqueando os anticorpos) e, portanto, é aplicável em diferentes modelos de inflamação vascular e permite a investigação de adesão funções de proteína ou o avaliação de compostos específicos.

<table border="0" cellpadding="0" cellspacing="0" style="width:939px;" width="938">
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	<tbody>
		<tr height="20">
			<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>
		<tr height="20">
			<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>
		</tr>
		<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>
		</tr>
		<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>
		</tr>
		<tr height="20">
			<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>
		</tr>
		<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

O recrutamento de leucócitos após lesão ou inflamação a locais de lesão ou dano tecidual foi investigado durante décadas recentes e resultou no conceito de cascata de adesão de leucócitos. No entanto, os mecanismos moleculares exatos envolvidos no recrutamento de leucócitos ainda não foram totalmente identificados. Desde o recrutamento de leucócitos continua a ser um tema importante no campo da infecção, inflamação e (auto) imune pesquisa, apresentamos um ensaio simples baseada em fluxo laminar para estudar os mecanismos subjacentes da adesão, de adesão, e transmigração de leucócitos sob regimes de fluxo arterial e venoso. O ensaio em vitro pode ser usado para estudar os mecanismos moleculares que fundamentam as interações entre leucócitos e seus parceiros celulares em diferentes modelos de inflamação vascular. Este protocolo descreve um ensaio baseado em fluxo laminar, utilizando uma câmara de fluxo paralelo e um microscópio de contraste de fase invertido conectado a uma câmera para estudar as interações de leucócitos e células endoteliais ou plaquetas, que podem ser visualizadas e gravadas em seguida análise off-line. Células endoteliais, plaquetas ou leucócitos podem ser pré-tratados com inibidores ou anticorpos para determinar o papel de moléculas específicas durante este processo. Condições de cisalhamento, ou seja, arterial ou venosa tensão de cisalhamento, podem ser facilmente adaptadas pela viscosidade e vazão dos fluidos perfundidos e a altura do canal.

Para estudar a adesão endotelial de leucócitos, células de THP-1 fluorescente etiquetadas foram perfundidas sobre uma monocamada endotelial TNFa - ou não-estimulada por 2 min em 3 Dina/cm2. O número total de células monocítica aderentes foi determinado após 2 min de perfusão capturando 6 campos independentes durante um período de 2-6 min. As células aderentes foram quantificadas pelo menos 6 imagens capturadas com um microscópio de fluorescência/contraste de fase i...

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

Ensaios baseados em fluxo laminar para investigar o recrutamento de leucócitos em culturas de células vasculares e plaquetas aderentes

Leucócitos, avidamente, interagir com células vasculares e plaquetas após lesão de parede do vaso ou durante a inflamação. Aqui, descrevemos um simples ensaio baseado em fluxo laminar para caracterizar os mecanismos moleculares que fundamentam as interações entre os leucócitos e os seus parceiros de celulares.

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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