1. Modificando poliméricos Superfícies com recCD47 NOTA:. O protocolo é resumido esquematicamente na Figura 1 A Figura 1A ilustra a geração de superfícies poliméricas tiol-reactivo Figura 1B ilustra a geração de recCD47 reactivo com tiol.. <ol><li> Dia 1 <ol><li> Prepara-se uma solução de PDT-BzPh (1 mg / ml) e bicarbonato de potássio (KHCO3) (0,7 mg / ml) em água estéril. Agita-se durante a noite a 4 ° C (protegido da luz). </li></ol></li><li> Dia 2 <ol><li> Cortar tubo polimérico em 40 centímetros de comprimento (o tempo suficiente para caber em torno de rodas rotativas). </li><li> Soak tubos em uma solução aquosa a 0,1% de hexacylpyridinium durante 90 minutos à temperatura ambiente num agitador ou em loop Aparelho Chandler. Lavar os tubos com 3x de água estéril após a 90 min de molho. </li><li> Acidifica-se a solução de PDT-BzPh do Dia 1 por adição de 15% de potássio monobásico aquoso (KH 2 </sub&gt; PO 4). Adicionar 50 ul de KH 2 PO 4 por ml de PDT-BzPh, formando uma solução micelar turvo. </li><li> Embeber os tubos na solução PDT-BzPh acidificada durante 40 minutos à temperatura ambiente num agitador ou no aparelho. </li><li> Lavar os tubos com ácido acético diluído (1: 1000), uma vez. </li><li> Expor os tubos a irradiação UV durante um período total de 60 minutos. Gire tubos de ¼ de volta a cada 15 min para irradiar toda a superfície. </li><li> Embeber os tubos com uma solução de 20 mg / ml de bicarbonato de potássio (KHCO3), durante 20 minutos à temperatura ambiente num agitador ou no aparelho. </li><li> Lavar os tubos com 3x de água estéril e armazenar a 4 ° C em água estéril. </li></ol></li><li> Dia 3 <ol><li> Dissolver 5 mg Sulfo- SMCC em 200 mL dimetilformamida (DMF) (Atenção: Realize em hotte). </li><li> Adicionar 50 ul da solução de Sulfo-SMCC, preparado no passo 1 a 0,1 mg / ml de solução de poli-lisina recCD47, e agita-se durante 60 min a rotemperatura om. </li><li> Durante 60 min de agitação, degas estéril Tampão fosfato de Dulbecco (DPBS) e reserve. </li><li> Purificar Sulfo- SMCC reagiu recCD47 usando um corte de coluna de dessalinização rotação 7K peso molecular por instruções do fabricante. Recolha de escoamento final (de alta qualidade tiol-reactivo recCD47) e diluir até ao volume necessário para revestir o interior do tubo com DPBS. </li><li> Lavar os tubos a partir do dia 2 com estéril, desgaseificadas DPBS 3x. </li><li> Reagir a superfície modificada dos tubos com uma solução de 20 mg / ml com tampão de tris (2-carboxietil) fosfina (TCEP) em DPBS desgaseificados durante menos de 2 minutos. Lavar os tubos com estéril desgaseificadas DPBS 4x. </li><li> Adicionar o recCD47 Sulfo-SMCC-reagido para os tubos e incubar durante a noite a 4 ° C num agitador ou em aparelhos. </li></ol></li></ol> 2 Imuno Quantificação de recCD47 em Superfícies Modificadas <ol><li> Lavar tubos adaptados para ser quantificado a partir do dia 3 sagacidadeh DPBS 3x. Tubos loja não utilizado para a quantificação em DPBS a 4 ° C. </li><li> Use uma biópsia por punção de 4 mm a fazer duplicados de amostras de tubo e colocar punções em poços de uma placa de 96 poços. </li><li> Preparar um controle negativo constituído por um tubo de amostra não modificada não tratados com o anticorpo de detecção. Preparar um anticorpo de controlo que consiste de um tubo de amostra não modificada tratados com o anticorpo de detecção. Preparar as amostras para ensaio de tubagem modificados tratados com o anticorpo de detecção. </li><li> Amostras do bloco com 0,4% de albumina de soro bovino (BSA) em DPBS durante 60 minutos à temperatura ambiente num agitador. </li><li> Após o bloqueio, aspirado BSA e enxágüe com Tris salina acrescida de 1% (TBST) 3x-20 Tween, 10 min cada um em uma coqueteleira. </li><li> Prepara-se uma diluição de trabalho de anticorpo em 0,4% de BSA de acordo com a diluição recomendada pelo fabricante para os imunoensaios. Diluir anticorpo CD47 humano B6H12-FITC a 1: 100 em 0,4% de BSA. </li><li> Adicionar 200 ul da diluição do anticorpo aos poços apropriados. Incubacontrolos negativos te com 0,4% de BSA. Incubar à temperatura ambiente durante 60 min, num agitador (proteger da luz). </li><li> Enxaguar com TBST 3x, 10 min cada um em uma coqueteleira. Aspirar o último enxágüe TBST e adicionar 200 DPBS ul para poços de amostra do tubo. </li><li> Recolhe-se o fluxo de passagem final, que é de alta qualidade tiol reactivos CD47 recombinante e diluir até ao volume necessário para revestir o interior dos tubos com DPBS. </li><li> Leia intensidade do sinal FITC utilizando um leitor de microplacas com FITC excitação (485 nm) e emissão (538 nm) configurações. </li><li> Calcular recCD47 ligado à superfície polimérica com base em valores de referência, correspondendo a autofluorescência e ligação não específica a partir da amostra de controlo sem anticorpo. </li></ol> 3. Chandler Circuito Aparelho Protocolo Procure Institutional Review Board (IRB) aprovação do protocolo de coleta de sangue e informado consentimento papelada antes do início da recolha de amostras de sangue humano. Obter informaçõesconfirmada através consentimento de um doador de sangue humano. NOTA: Um diagrama que representa o aparelho é mostrado na Figura 2. <ol><li> Encha banho de água com água destilada até aproximadamente 1/2 do diâmetro das rodas estão submersas. Adicionar branqueador suficiente para o banho de água para fazer uma solução de lixívia a 10%. Definir banho de água a 37 ° C e deixar equilibrar à temperatura. </li><li> Reunir placas de metal (mostrados na Figura 1B), tubos não modificada e modificada tubagem, e montar em torno de rodas de aparelhos, como mostrado na Figura 1C. Certifique-se de que os tubos se encaixa confortavelmente em torno da roda com a placa de metal no local. </li><li> Obter 30 ml de amostra de sangue utilizando um protocolo IRB-aprovado, em um frasco pré-cheio com 2 ml de citrato ou outro anticoagulante, e misturar por inversão para evitar a coagulação, uma vez que a amostra tenha sido recolhida. </li><li> Adicionar cerca de 10 ml de sangue para cada tubo, utilizando a válvula e uma seringa de metal, deixando um pouco de ar no tubo. Fixe a tampa da válvula e rotate durante 3 horas. </li><li> Drenar o sangue em um copo de resíduos tratados com uma solução de água sanitária a 10% (ou conforme exigido pela política institucional). </li><li> Gentilmente lavar interior tubulação com DPBS para remover todos os vestígios de sangue. Recolha de escoamento no copo de resíduos. Descarte de sangue em conformidade com a política institucional. </li><li> Desinfectar o aparelho e qualquer contato com sangue superfícies usando uma solução de água sanitária a 10% ou de acordo com a política institucional. </li><li> Amostras de processo para a microscopia eletrônica de varredura ou microscópio fluorescente, conforme descrito abaixo. </li></ol> 4. Microscopia fluorescente e contando celular <ol><li> Prepare uma solução de paraformaldeído 4% (PFA) (Atenção: Realize em hotte). </li><li> Incubar tubagem numa solução PFA a 4% durante a noite a 4 ° C. </li><li> Após incubação durante a noite, retire PFA 4% e enxaguar filmes muito suavemente com DPBS. </li><li> Corte o tubo em seções para expor a superfície do lúmen para a coloração. </li><li> Stainuma secção do tubo com algumas gotas de meios de montagem com o 4 &#39;, 6-diamidino-2-fenilindole (DAPI), durante 30 min à temperatura ambiente (proteger da luz). Após a coloração, lavar a tubulação muito suavemente com DPBS para reduzir o sinal DAPI fundo. </li><li> Imagem usando um microscópio de fluorescência equipado com um filtro de DAPI e câmara digital para contar o número de células em 9 campos cegamente seleccionados de vista sob uma ampliação de 200X. </li><li> Célula registro contagens por campo de visão e realizar análises estatísticas apropriadas para determinar a significância estatística dos resultados. </li></ol> 5. Microscopia Eletrônica de Varredura <ol><li> Prepare uma solução de glutaraldeído 2% (Atenção: Realize em hotte). </li><li> Incubar tubagem numa solução de glutaraldeído a 2% durante a noite a 4 ° C. </li><li> Após incubação durante a noite, lavar cuidadosamente o tubo de 3x com DPBS. </li><li> Prepare uma solução de 1% de tetróxido de ósmio (Cuidado: perigo de inalação grave! Use em hotte). </li><li> Incubar a tubagem para uma solução a 1% de tetróxido de ósmio durante 15 minutos à temperatura ambiente. </li><li> Lave o tubo de 3x com DPBS. </li><li> Prepara-se uma série de concentrações de etanol (25%, 50%, 75%, 95%, e 100% de etanol). </li><li> Desidratar a tubagem por incubação em série de concentrações de etanol. Incubar em 25%, 50%, 75%, e etanol a 95% durante 20 min cada. Incubar em etanol a 100% durante 30 min. </li><li> Ponto supercrítico secar a tubulação com CO 2 por 45 min para remover toda a umidade. </li><li> Secções tubulares montar em um esboço espécime com pasta de prata ou grafite. </li><li> Secções tubulares de revestimento com 12,5 nm de ouro-paládio. </li><li> Analisar em um microscópio eletrônico de varredura. </li></ol>

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A pesquisa relatada nesta publicação foi apoiada pelo Instituto Nacional de Imagem Biomédica e Bioengenharia, sob o número prêmio R21 EB015612 (SJS), e do National Heart, Lung, and Blood Institute, sob o número prêmio T32 HL007915 (JBS e RJL), da National Institute of Health.

A química fotoativação (resumidos na Figura 1) permite a modificação de praticamente qualquer superfície de polímero que tem hidrocarbonetos suficientes para facilitar PDT-BzPh apego e irradiação UV subseqüente ao photo-ativar o PDT-BzPh. Funcionalização da superfície polimérica com grupos tiol reactivos permite a subsequente ligação de uma série de moléculas de interesse testáveis. Em nossos estudos específicos que escolhemos recombinante CD47 11-13. A conjugação quími...

Muitos procedimentos clínicos, tais como a circulação extracorpórea e diálise renal, requerem o uso de condutos de sangue poliméricas e são frequentemente associados com complicações pós-procedimento 1. Quando perfundido com sangue, estes polímeros ilícito a reação de corpo estranho (FBR), resultando na adsorção de proteínas do sangue e plaquetas, a adesão de monócitos / macrófagos e liberação de citocinas pró-inflamatórias, o que contribui para complicações pós-procedimento e / ou 2,3 falha do dispositivo. Assim, estratégias para abordar esta questão continuar a ser uma área importante e contínuo de pesquisas em biomateriais. Os pesquisadores têm tentado resolver este problema modificando sangue entrar em contato com as superfícies com bioativos ou bio-inerte moléculas 4-6. A investigação no nosso laboratório tem-se centrado em acrescentando CD47 recombinante (recCD47) a biomateriais poliméricos como uma estratégia para mitigar o FBR e aumentar a eficácia destes materiais. CD47 é uma transmembr expressa ubiquamenteane proteína com um papel conhecido na evasão da resposta imune, conferindo status de &quot;self&quot; em cima de expressar as células 7-10 e mostra a promessa de conferir biocompatibilidade quando anexado a superfícies poliméricas 11-13. Sinal-alfa proteína reguladora (SIRPα), o receptor cognato para o CD47, e um membro do motivo inibidor de imunorreceptores baseado em tirosina (ITIM) molecular contendo família de proteínas transmembranares, é expresso em células de origem mielóide 14. Nós já anteriormente demonstrado que a CD47, por meio de sinalização celular mediada SIRPα, sub-regula as respostas imunitárias a de poliuretano (PU) e de cloreto de polivinilo (PVC) em in vitro, ex vivo e in vivo em modelos de 11-13. Central de nossas investigações é uma relativamente nova química fotoactivação, aqui descrito, em que os grupos tiol reactivos quimicamente são covalentemente anexado ao tubo polimérico fazendo reagir o tubo com um polímero multifuncional (PDT-BzPh), composto de 2-piridilditio (PDT), a benzofenona fotoreactivo (BzPh) e uma polialilamina modificado por carboxi 11-13. A redução dos grupos PDT covalentemente anexas com tris (2-carboxietil) fosfina (TCEP) 11 produz uma superfície que pode ser tiolado subsequentemente reagido com porções terapêuticas. Aqui e anteriormente detalhada 12,13, recCD47, adicionalmente modificado com a adição de uma cauda poli-lisina C-terminal de 12,13, é feito reagir com sulfossuccinimidil-4-[N -maleimidomethyl] ciclo-hexano-1-carboxilato (sulfo-SMCC) durante 1 h para gerar grupos tiol-reactivo, que permite a formação da ligação entre o tubo monossulfureto e recCD47 11. A capacidade anti-inflamatória das superfícies funcionalizadas CD47 foi testado, ex viv o, utilizando o Aparelho de Chandler loop com sangue humano total, que foi inicialmente descrita em 1958 como um modelo in vitro da coagulação trombótica 15. O aparelho baseia-se numasistema de tubos fechado parcialmente cheio com ar e um motor rotativo para fazer circular o sangue através da tubagem 15. Este modelo experimental, proporciona a oportunidade de estudar o efeito da exposição a sangue sobre superfícies modificadas e não modificadas, bem como o efeito destas modificações de superfície sobre a fisiologia das células do sangue. recCD47 pode ser anexado a uma variedade de superfícies de polímeros, utilizando química de fotoactivação este, e a sua capacidade anti-inflamatória pode ser avaliada utilizando um modelo clinicamente relevante ex vivo imitando perfusão do sangue sobre as superfícies poliméricas 11,12. Condutas de sangue grau clínico modificados com recCD47 mostram significativamente menos de plaquetas e ligação de células inflamatórias, em comparação com os polímeros não modificados quando expostos a sangue humano no dispositivo. Uma descrição passo-a-passo do presente processo de modificação é detalhado abaixo.

<table border="0" cellpadding="0" cellspacing="0" width="802">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Name</td>
			<td style="width:175px;">Company</td>
			<td style="width:107px;">Catalog Number</td>
			<td style="width:251px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">16% Paraformaldehyde (PFA)</td>
			<td style="width:175px;">Thermo Scientific</td>
			<td style="width:107px;">58906</td>
			<td>Caution! Use in fume hood</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">25% Glutaraldehyde</td>
			<td style="width:175px;">VWR</td>
			<td style="width:107px;">AAA17876-AP&#160;</td>
			<td>Caution! Use in fume hood</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">2-pyridyldithio,benzophenone (PDT-BzPH)</td>
			<td style="width:175px;">Synthesized in lab</td>
			<td style="width:107px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Bovine Serum Albumin (BSA)</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:107px;">A3059-100G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Citrate</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:107px;">S5770-50ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Digital Camera</td>
			<td style="width:175px;">Leica</td>
			<td style="width:107px;">DC500</td>
			<td>Out of production</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Dimethylformamide (DMF)</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:107px;">270547-100ML</td>
			<td>Caution! Use in fume hood</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Dulbecco&#8217;s Phosphate Buffered Saline (DPBS)</td>
			<td style="width:175px;">Gibco/Life Technologies</td>
			<td style="width:107px;">14190-136</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Fluorescent Microscope</td>
			<td style="width:175px;">Nikon</td>
			<td style="width:107px;">TE300</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Glacial Acetic Acid</td>
			<td style="width:175px;">Fisher Scientific</td>
			<td style="width:107px;">A38-212</td>
			<td>Caution! Use in fume hood</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Human CD47 (B6H12) &#8211; FITC Antibody</td>
			<td style="width:175px;">Santa Cruz Biotechnology</td>
			<td style="width:107px;">SC-12730</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Osmium Tetroxide</td>
			<td style="width:175px;">Acros Organics</td>
			<td style="width:107px;">197450050</td>
			<td>Caution! Use in fume hood</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Potassium Bicarbonate (KHCO3)</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:107px;">237205-100G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Potassium Phosphate Monobasic (KH2PO4)</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:107px;">P5655-100G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">PVC Tubing (Cardiovascular Procedure Kit)</td>
			<td style="width:175px;">Terumo Cardiovascular Systems</td>
			<td style="width:107px;">60050</td>
			<td>Most clinical-grade tubing will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Scanning Electron Microscope</td>
			<td>JEOL</td>
			<td>JSM-T330A</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:269px;">Sodium Chloride (NaCl)</td>
			<td style="width:175px;">Fisher Scientific</td>
			<td>BP358-212</td>
			<td></td>
		</tr>
		<tr height="36">
			<td height="36" style="height:36px;width:269px;">Microplate Reader</td>
			<td style="width:175px;">Molecular Devices</td>
			<td style="width:107px;">Spectramax Gemini EM&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Sulfo-SMCC</td>
			<td style="width:175px;">Sigma</td>
			<td style="width:107px;">M6035-10MG</td>
			<td>Moisture Sensitive!</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">tris (2-carboxyethyl) phosphine (TCEP-HCl)</td>
			<td style="width:175px;">Thermo Scientific</td>
			<td style="width:107px;">20491</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:269px;">Tris Base</td>
			<td style="width:175px;">Sigma</td>
			<td>T1503-100G</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;width:269px;">Tween-20</td>
			<td>Bio-Rad</td>
			<td>170-6531</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Vectashield with DAPI</td>
			<td style="width:175px;">Fisher Scientific</td>
			<td style="width:107px;">H-1200</td>
			<td>Light sensitive!</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Zeba Spin Desalt Columns &#8211; 7K MWCO</td>
			<td style="width:175px;">Thermo Scientific</td>
			<td style="width:107px;">89891</td>
			<td></td>
		</tr>
	</tbody>
</table>

the use of the ex vivo chandler loop apparatus to assess the biocompatibility of modified polymeric blood conduits

A reacção de corpo estranho ocorre quando uma superfície sintética é introduzida no corpo. Caracteriza-se por adsorção de proteínas do sangue e a subsequente ligação e activação de plaquetas, monócitos / macrófagos de adesão, e os eventos de sinalização celular inflamatório, levando a complicações pós-procedimento. O Aparelho Chandler laço é um sistema experimental que permite aos investigadores a estudar as interacções celulares e moleculares que ocorrem quando grandes volumes de sangue são perfundidos sobre condutas poliméricos. Para esse efeito, o aparelho tem sido utilizado como um modelo ex vivo, permitindo que a avaliação das propriedades anti-inflamatórias de várias modificações da superfície do polímero. Nosso laboratório mostrou que condutas de sangue, covalentemente modificadas via química fotoativação com CD47 recombinante, pode conferir biocompatibilidade de superfícies poliméricas. Acrescentando CD47 para superfícies poliméricas pode ser um meio eficaz para promover a eficácia das condutas de sangue poliméricos. Seuein é a metodologia que detalha a química fotoativação usado para acrescentar CD47 recombinante para condutas de sangue poliméricos clinicamente relevantes e com o uso do laço Chandler como um modelo experimental ex vivo para examinar interações sangue com a CD47 modificado e controle de condutas.

Gerando superfícies poliméricas tiol-reactivo por meio do uso de PDT-BzPh e TCEP juntamente com tiol-reactivo recCD47 poli-lisina usando SMCC permite a fixação de recCD47 a superfícies poliméricas. O processo de modificação é resumida esquematicamente na Figura 1. A conveniência deste processo de modificação é que ele pode ser aplicado a muitas proteínas diferentes e as diversas superfícies poliméricas diferentes, assumindo que a proteína pode ser modificado com grupos quimicamente reac...

Watch this Scientific Journal Video about The Use of the Ex Vivo Chandler Loop Apparatus to Assess the Biocompatibility of Modified Polymeric Blood Conduits at JoVE.com

The Use of the Ex Vivo Chandler Loop Apparatus to Assess the Biocompatibility of Modified Polymeric Blood Conduits

Blood exposure to polymeric blood conduits initiates the foreign body reaction that has been implicated in clinical complications. Here, the Chandler Loop Apparatus, an experimental tool mimicking blood perfusion through these conduits, is described. Appendage of recombinant CD47 results in decreased evidence of the foreign body reaction on these conduits.

O uso do<em&gt; Ex Vivo</em&gt; Chandler Circuito Aparelho para avaliar a biocompatibilidade de Modificados Condutas sangue Poliméricos

The foreign body reaction occurs when a synthetic surface is introduced to the body. It is characterized by adsorption of blood proteins and the ...

the-use-ex-vivo-chandler-loop-apparatus-to-assess-biocompatibility

Research

JoVE Journal

Bioengineering

The Use of the Ex Vivo Chandler Loop Apparatus to Assess the Biocompatibility of Modified Polymeric Blood Conduits

11.5K visualizações.  The Children's Hospital of Philadelphia. Blood exposure to polymeric blood conduits initiates the foreign body reaction that has been implicated in clinical complications. Here, the Chandler Loop Apparatus, an experimental tool mimicking blood perfusion through these conduits, is described. Appendage of recombinant CD47 results in decreased evidence of the foreign body reaction on these conduits. 

Vídeo: The Use of the Ex Vivo Chandler Loop Apparatus to Assess the Biocompatibility of Modified Polymeric Blood Conduits

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage1-3. Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease4. 
The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve5. Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves6-9. Pulsatile bioreactors have also been developed to study a range of tissues including cartilage10, bone11 and bladder12. The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. 
The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

A cyclic pressure bioreactor capable of subjecting heart valve tissue to physiological and pathological pressure conditions has been designed. A LabVIEW program allows users to control pressure magnitude, amplitude and frequency. This device can be used to study the mechanobiology of heart valve tissue or isolated cells.

Projeto de um biorreator de pressão cíclica para o Ex Vivo Estudo de válvulas cardíacas Aórtica

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic ...

Bioengenharia

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

Decades ago the human placenta was thought to be an impenetrable barrier between mother and unborn child. However, the discovery of thalidomide-induced birth defects and many later studies afterwards proved the opposite. Today several harmful xenobiotics like nicotine, heroin, methadone or drugs as well as environmental pollutants were described to overcome this barrier. With the growing use of nanotechnology, the placenta is likely to come into contact with novel nanoparticles either accidentally through exposure or intentionally in the case of potential nanomedical applications. Data from animal experiments cannot be extrapolated to humans because the placenta is the most species-specific mammalian organ 1. Therefore, the ex vivo dual recirculating human placental perfusion, developed by Panigel et al. in 1967 2 and continuously modified by Schneider et al. in 1972 3, can serve as an excellent model to study the transfer of xenobiotics or particles.
Here, we focus on the ex vivo dual recirculating human placental perfusion protocol and its further development to acquire reproducible results.
The placentae were obtained after informed consent of the mothers from uncomplicated term pregnancies undergoing caesarean delivery. The fetal and maternal vessels of an intact cotyledon were cannulated and perfused at least for five hours. As a model particle fluorescently labelled polystyrene particles with sizes of 80 and 500 nm in diameter were added to the maternal circuit. The 80 nm particles were able to cross the placental barrier and provide a perfect example for a substance which is transferred across the placenta to the fetus while the 500 nm particles were retained in the placental tissue or maternal circuit. The ex vivo human placental perfusion model is one of few models providing reliable information about the transport behavior of xenobiotics at an important tissue barrier which delivers predictive and clinical relevant data.

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

The ex vivo dual recirculating human placental perfusion model can be used to investigate the transfer of xenobiotics and nanoparticles across the human placenta. In this video protocol we describe the equipment and techniques required for a successful execution of a placenta perfusion.

Determinação da taxa de transporte de xenobióticos e nanomateriais através da placenta usando o<em&gt; Ex vivo</em&gt; Modelo de perfusão da placenta humana

Decades ago the human placenta was thought to be an impenetrable barrier between mother and unborn child. However, the discovery of thalidomide-induced ...

Improved Method for the Preparation of a Human Cell-based, Contact Model of the Blood-Brain Barrier

The blood-brain barrier (BBB) comprises impermeable but adaptable brain capillaries which tightly control the brain environment. Failure of the BBB has been implied in the etiology of many brain pathologies, creating a need for development of human in vitro BBB models to assist in clinically-relevant research. Among the numerous BBB models thus far described, a static (without flow), contact BBB model, where astrocytes and brain endothelial cells (BECs) are cocultured on the opposite sides of a porous membrane, emerged as a simplified yet authentic system to simulate the BBB with high throughput screening capacity. Nevertheless the generation of such model presents few technical challenges. Here, we describe a protocol for preparation of a contact human BBB model utilizing a novel combination of primary human BECs and immortalized human astrocytes. Specifically, we detail an innovative method for cell-seeding on inverted inserts as well as specify insert staining techniques and exemplify how we use our model for BBB-related research.

Establishment of human models of the blood-brain barrier (BBB) can benefit research into brain conditions associated with BBB failure. We describe here an improved technique for preparation of a contact BBB model, which permits coculturing of human astrocytes and brain endothelial cells on the opposite sides of a porous membrane.

Melhoria da Metodologia para a Elaboração de um baseado em celular, Contact Modelo Humano da barreira hemato-encefálica

The blood-brain barrier (BBB) comprises impermeable but adaptable brain capillaries which tightly control the brain environment. Failure of the BBB has ...

Gene Transfection toward Spheroid Cells on Micropatterned Culture Plates for Genetically-modified Cell Transplantation

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. The cell spheroids are prepared in a culture system on micropatterned plates coated with a thermosensitive polymer. A number of spheroids are formed on the plates, corresponding to the cell adhesion areas of 100 &#181;m diameter that are regularly arrayed in a two-dimensional manner, surrounded by non-adhesive areas that are coated by a polyethylene glycol (PEG) matrix. The spheroids can be easily recovered as a liquid suspension by lowering the temperature of the plates, and their structure is well maintained by passing them through injection needles with a sufficiently large caliber (over 27 G). Genetic modification is achieved by gene transfection using the original non-viral gene carrier, polyplex nanomicelle, which is capable of introducing genes into cells without disrupting the spheroid structure. For primary hepatocyte spheroids transfected with a luciferase-expressing gene, the luciferase is sustainably obtained in transplanted animals, along with preserved hepatocyte function, as indicated by albumin expression. This system can be applied to a variety of cell types including mesenchymal stem cells.

This protocol describes a cell transplantation system using genetically modified, injectable spheroids. Cell spheroids are cultured on micropatterned culture plates and recovered after gene introduction using polyplex nanomicelles. This system facilitates prolonged transgene expression from the transplanted cells in host animals while maintaining the innate function of the cells.

A transfecção Gene direção Células Spheroid em placas micropadronadas Cultura para Transplante de Células geneticamente modificados

To improve the therapeutic effectiveness of cell transplantation, a transplantation system of genetically modified, injectable spheroids was developed. ...

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

Increasing the performance of submucosal injection materials (SIMs) is important for endoscopic therapy of early gastrointestinal cancer. It is essential to establish an ex vivo model that can evaluate SIM performance accurately, for developing high-performance SIMs. In our previous study, we developed a new ex vivo model that can be used to evaluate the performance of various SIMs in detail by applying constant tension to the specimen&#39;s ends. We also confirmed that the proposed new ex vivo model allows accurate submucosal elevation height (SEH) measurement under uniform conditions and detailed comparisons of the performances of various types of SIMs. Here, we describe the new ex vivo model and explain the detailed setup methodology of this model. Since all parts of the new model were easy to obtain, the setup of the new model could be completed quickly. SEH of various SIMs could be measured more accurately by using the new model. The critical factor that determines SIM performance can be identified using the new model. SIM development speed will drastically increase after the factor has been identified.

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

We developed a new ex vivo model that applies constant tension to the porcine gastric specimen. This development made it possible to evaluate the performance (the height and duration of the submucosal elevation) of various SIMs accurately.&#160; The detailed setup methodology of this new model is explained.

Um novo modelo Ex Vivo para a avaliação de desempenho de Material de injeção submucosa endoscópica

Increasing the performance of submucosal injection materials (SIMs) is important for endoscopic therapy of early gastrointestinal cancer. It is essential ...

Intra-cardiac Side-Firing Light Catheter for Monitoring Cellular Metabolism using Transmural Absorbance Spectroscopy of Perfused Mammalian Hearts

Absorbance spectroscopy of cardiac muscle provides non-destructive assessment of cytosolic and mitochondrial oxygenation via myoglobin and cytochrome absorbance respectively. In addition, numerous aspects of the mitochondrial metabolic status such as membrane potential and substrate entry can also be estimated. To perform cardiac wall transmission optical spectroscopy, a commercially available side-firing optical fiber catheter is placed in the left ventricle of the isolated perfused heart as a light source. Light passing through the heart wall is collected with an external optical fiber to perform optical spectroscopy of the heart in near real- time. The transmission approach avoids numerous surface scattering interference occurring in widely used reflection approaches. Changes in transmural absorbance spectra were deconvolved using a library of chromophore reference spectra, providing quantitative measures of all the known cardiac chromophores simultaneously. This spectral deconvolution approach eliminated intrinsic errors that may result from using common dual wavelength methods applied to overlapping absorbance spectra, as well as provided a quantitative evaluation of the goodness of fit. A custom program was designed for data acquisition and analysis, which permitted the investigator to monitor the metabolic state of the preparation during the experiment. These relatively simple additions to the standard heart perfusion system provide a unique insight into the metabolic state of the heart wall in addition to conventional measures of contraction, perfusion, and substrate/oxygen extraction.

Here we introduce a method for using an intra-ventricle optical catheter in perfused hearts to perform absorbance spectroscopy across the heart wall. The data obtained provides robust information on tissue oxygen tension as well as substrate utilization and membrane potential simultaneously with cardiac performance measures in this ubiquitous preparation.

Cateter de luz de queima lateral intra-cardíaco para monitoramento do metabolismo celular usando espectroscopia de absorvência transmural de corações de mamíferos perfused

Absorbance spectroscopy of cardiac muscle provides non-destructive assessment of cytosolic and mitochondrial oxygenation via myoglobin and cytochrome ...

Blood Flow Imaging with Ultrafast Doppler

The pulsed-Doppler effect is the main technique used in clinical echography to assess blood flow. Applied with conventional focused ultrasound Doppler modes, it has several limits. Firstly, a finely tuned signal filtering operation is needed to distinguish blood flows from surrounding moving tissues. Secondly, the operator must choose between localizing the blood flows or quantifying them. In the last two decades, ultrasound imaging has undergone a paradigm shift with the emergence of ultrafast ultrasound using unfocused waves. In addition to a hundredfold increase in framerate (up to 10000 Hz), this new technique also breaks the conventional quantification/localization trade-off, offering a complete blood flow mapping of the field of view and a simultaneous access to fine velocities measurements at the single-pixel level (down to 50 &#181;m). This data continuity in both spatial and temporal dimensions strongly improves the tissue/blood filtering process, which results in an increase sensitivity to small blood flow velocities (down to 1 mm/s). In this method paper, we aim to introduce the concept of ultrafast Doppler as well as its main parameters. Firstly, we summarize the physical principles of unfocused wave imaging. Then, we present the Doppler signal processing main steps. Particularly, we explain the practical implementation of the critical tissue/blood flow separation algorithms and on the extraction of velocities from these filtered data. This theoretical description is supplemented by in vitro experiences. A tissue phantom embedding a canal with flowing blood-mimicking fluid is imaged with a research programmable ultrasound system. A blood flow image is obtained and the flow characteristics are displayed for several pixels in the canal. Finally, a review of in vivo applications is proposed, showing examples in several organs such as carotids, kidney, thyroid, brain and heart.

This protocol shows how to apply ultrafast ultrasound Doppler imaging to quantify blood flows. After a 1 s long acquisition, the experimenter has access to a movie of the full field of view with axial velocity values for each pixel every &#8776;0.3 ms (depending on the ultrasound time of flight).

Imagem de fluxo sanguíneo com Doppler Ultrarrápido

The pulsed-Doppler effect is the main technique used in clinical echography to assess blood flow. Applied with conventional focused ultrasound Doppler ...

&quot;Avatar&quot;- Optimized Ex Vivo Work Loop Experiment to Emulate In Vivo Muscle Force

"Avatar", a Modified Ex vivo Work Loop Experiments Using In vivo Strain and Activation

Movement behaviors are emergent features of dynamic systems that result from muscle force production and work output. The interplay between neural and mechanical systems occurs at all levels of biological organization concurrently, from the tuning of leg muscle properties while running to the dynamics of the limbs interacting with the ground. Understanding the conditions under which animals shift their neural control strategies toward intrinsic muscle mechanics (&#39;preflexes&#39;) in the control hierarchy would allow muscle models to predict in vivo muscle force and work more accurately. To understand in vivo muscle mechanics, ex vivo investigation of muscle force and work under dynamically varying strain and loading conditions similar to in vivo locomotion is required. In vivo strain trajectories typically exhibit abrupt changes (i.e., strain and velocity transients) that arise from interactions among neural activation, musculoskeletal kinematics, and loads applied by the environment. The principal goal of our &#34;avatar&#34; technique is to investigate how muscles function during abrupt changes in strain rate and loading when the contribution of intrinsic mechanical properties to muscle force production may be highest. In the &#34;avatar&#34; technique, the traditional work-loop approach is modified using measured in vivo strain trajectories and electromyographic (EMG) signals from animals during dynamic movements to drive ex vivo muscles through multiple stretch-shortening cycles. This approach is similar to the work-loop technique, except that in vivo strain trajectories are scaled appropriately and imposed on ex vivo mouse muscles attached to a servo motor. This technique allows one to: (1) emulate in vivo strain, activation, stride frequency, and work-loop patterns; (2) vary these patterns to match in vivo force responses most accurately; and (3) vary specific features of strain and/or activation in controlled combinations to test mechanistic hypotheses.

Author Spotlight: Bridging the Gap Between In Vivo and Ex Vivo Studies with the &quot;Avatar&quot; Technique to Advance Muscle Mechanics Research 

This article details the methodology for emulating in vivo muscle force production during ex vivo work loop experiments using an "avatar" muscle from a laboratory rodent to assess the contributions of strain transients and activation to the muscle force response.

Movement behaviors are emergent features of dynamic systems that result from muscle force production and work output. The interplay between neural and ...

Preparation of Cardiomyocytes and Setting-Up the Apparatus for the Slow Injection Method

Prepare the 10%gelatin stock solution by weighing and dissolving the gelatin in the ADS buffer, and autoclaving the solution. Rewarm the 10%gelatin stock at 37 degrees Celsius, until it becomes liquid. Then dilute the gelatin stock, using a prewarmed ADS buffer, to obtain the final injectable 5%gelatin solution.Suspend 96 cardiomyocyte balls in 100 microliters of prewarmed injection solution. Load the cardiomyocyte ball suspension into the cell injection syringe without aspirating the excess air. Next, hold the syringe vertically, with the needle facing upward, and tap the syringe to collect the bubbles at the upper ridge of the syringe.Also, observe the cardiomyocyte balls gradually settling onto the rubber seal of the plunger. Maintain the vertical position of the syringe, and slowly push the plunger to discard the bubbles and excess cell suspension solution, until 20 microliters of the cell suspension remain in the syringe, and the cardiomyocyte ball remains resting on the rubber seal of the plunger. Once done, immerse the capped syringe in an ice bath for five minutes, and fix the injection syringe apparatus on the animal stage before activating the main syringe pump during percutaneous cell transplantation in an anesthetized rat.

Preparação dos cardiomiócitos e montagem do aparelho para o método de injeção lenta

Análise de modelos de barreira hematoencefálica via coloração por imunofluorescência

Use of the MicroSiM (&#181;SiM) Barrier Tissue Platform for Modeling the Blood-Brain Barrier

The microSiM (&#181;SiM) is a membrane-based culture platform for modeling the blood-brain barrier (BBB). Unlike conventional membrane-based platforms, the&#160;&#181;SiM provides experimentalists with new capabilities, including live cell imaging, unhindered paracrine signaling between &#39;blood&#39; and &#39;brain&#39; chambers, and the ability to directly image immunofluorescence without the need for the extraction/remounting of membranes. Here we demonstrate the basic use of the platform to establish monoculture (endothelial cells) and co-culture (endothelial cells and pericytes) models of the BBB using ultrathin nanoporous silicon-nitride membranes. We demonstrate compatibility with both primary cell cultures and human induced pluripotent stem cell (hiPSC) cultures. We provide methods for qualitative analysis of BBB models via immunofluorescence staining and demonstrate the use of the &#181;SiM for the quantitative assessment of barrier function in a small molecule permeability assay. The methods provided should enable users to establish their barrier models on the platform, advancing the use of tissue chip technology for studying human tissues.

Autor em destaque: Avançando o uso da tecnologia de chip de tecido para estudar tecidos humanos 

This report provides protocols for assembly, cell culture, and assays on the &#181;SiM platform for the construction of blood-brain barrier models.

Uso da Plataforma de Tecido de Barreira MicroSiM (μSiM) para Modelagem da Barreira Hematoencefálica

The microSiM (&#181;SiM) is a membrane-based culture platform for modeling the blood-brain barrier (BBB). Unlike conventional membrane-based platforms, ...