Os autores são gratos a Shad Schipke Chesser e Daniel para a sua assistência com o design e fabricação do sistema e Myles Valtresa de assistência com a preparação do manuscrito.

1. Colheita e Preparação dos tecidos <ol><li> Valva aórtica devem ser coletadas de suínos adultos pesando não mais de £ 120 imediatamente após a morte. </li><li> Lavar as válvulas duas vezes com solução salina tamponada estéril de fosfato (PBS) e transporte para o laboratório em gelo. </li><li> Todas as etapas subseqüentes devem ser realizados em condições estéreis. </li><li> Assegurar que os folhetos não mostram qualquer sinal de degeneração, rasgar ou calcificação. Remover folhetos a partir da raiz da aorta, cortando 1 / 3 da distância entre o anel. </li><li> Folhetos lugar em poços individuais de uma placa de seis poços e incubar durante a noite com média de 3 ml de Dulbecco Modificado Águia suplementado com 1% de solução anti-biotic/anti-mycotic e 10% de soro fetal bovino a 37 ° C e 5% de CO 2. </li><li> Como alternativa, células isoladas podem ser semeados em placas de seis cultura e bem utilizada no dispositivo de pressão. Isolamento de células endoteliais e válvula de células intersticiais podem ser realizados conforme descrito anteriormente 13, 14. </li></ol> 2. Estudos pressão <ol><li> Um sistema de pressão feito por encomenda foi projetado para estudar os efeitos de pressão cíclica mechanobiological em tecido de válvula aórtica 15. </li><li> Faça logon no computador e abra o programa LabVIEW (Figura 1). </li><li> Calibração: <ol><li> Antes da experimentação, o sistema deve estar devidamente calibrado. </li><li> Ligue o fornecimento de energia para a placa de circuito. Esta fornece energia para as válvulas solenóides que controlam o fluxo de ar para dentro e para fora da câmara. </li><li> Verifique se o ar comprimido é conectado ao sistema e abrir o suprimento de ar à velocidade total. </li><li> Ligar o amplificador de sinal. Certifique-se a leitura da tensão é de 0,00. Ajustar conforme necessário </li><li> A interface LabVIEW tem um interruptor marcado &quot;TEST / RECORD&quot;. Verifique se a chave é definido como &quot;TEST&quot;. Clique no botão &quot;Air Supply&quot; para abrir a válvula solenóide de entrada. </li><li> Usando o regulador de pressão de gás, pressurizar a câmara com ar comprimido a um PSI. A pressão na câmara pode ser lido através do indicador de pressão digital localizado na parte traseira de placa terminal da câmara. Uma vez que a pressão tem equilibrado, gravar a leitura da tensão do amplificador de sinal. Repita o procedimento para PSI 2, 3, 4 e 5. </li><li> Construir uma curva de calibração de pressão versus tensão. A pressão deve ser convertido de PSI para mmHg. A equação do gráfico pode ser colocado no código do programa LabVIEW </li></ol></li><li> Remova a placa frontal de alumínio da câmara de pressão e pulverizar a câmara com etanol 70%. Deixe por um mínimo de 10 minutos para permitir que vapores de etanol residual a se dissipar. </li><li> Coloque a placa de seis poços contendo as amostras de folheto para a câmara e substituir a placa dianteira. Garantir a vedação é hermética, apertando as porcas localizados nas quatro hastes rosqueadas (localizado em cada canto da placa de final) com a mão. Coloque a câmara de pressão nos 37 ° C incubadora. Um diagrama esquemático da câmara de pressão é mostrado na figura 2. </li><li> A interface irá solicitar ao usuário para fornecer a quantidade de tempo que o sistema de ciclos entre entrada de ar comprimido e de saída. Estes devem ser definidos para 0.6s e 0.4s para imitar as condições diastólica e sistólica, respectivamente, a uma freqüência de 1Hz. O usuário também deve inserir um caminho de arquivo de dados. </li><li> No LabVIEW, clique em Executar e mudar o &quot;TEST / RECORD&quot; alternar para &quot;RECORD&quot;. </li><li> Certifique-se que a pressão está no nível desejado usando o gráfico na interface do LabVIEW. Pressão pode ser ajustado com o regulador de pressão de gás. </li><li> Executar o programa de período de tempo desejado. </li><li> Uma vez que a experiência é completa, clique no botão parar em LabVIEW, desligue a alimentação de ar e abrir a válvula de escape na câmara de pressão. </li><li> Remova a placa frontal da câmara e recuperar amostras de seis bem placa contendo. Amostras podem agora ser analisados ​​para a expressão do gene, a expressão da proteína, histologia, propriedades mecânicas, etc </li></ol> 3. Resultados representativos: O sistema de pressão é capaz de simular as pressões máxima transvalvar observado sob normotensos, estágios I e II condições hipertensos. No entanto, a pressão não foi capaz de imitar o gradiente de pressão sistólica, que é essencialmente zero in vivo. Freqüência é mantida em 1Hz, com um tempo de entrada de ar 0.6s e um tempo de escape de 0.4s. Pressão representante formas de onda de condições normais de pressão e elevada obtidos a partir do sistema pode ser visto na figura 3. <img src="/files/ftp_upload/3316/3316fig1.jpg" alt="Figura 1"/> Figura 1: Captura de tela da interface do LabVIEW. <img src="/files/ftp_upload/3316/3316fig2.jpg" alt="Figura 2"/> Figura 2: Desenho esquemático da câmara de pressão de vista Isometric A. da câmara de pressão; B. Vista lateral da câmara de pressão;C. Vista superior da câmara de pressão. <img src="/files/ftp_upload/3316/3316fig3.jpg" alt="Figura 3"/> Figura 3: Gráfico de simulação de pressão dentro da câmara de pressão (A) normotensos, (B) Fase I hipertensos, e (C) Estágio II condições hipertensos.

<ol>
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C., Yeger, H., Cartwright, L., Shou, Z., Radisic, M., Haig, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Feasibility+study+of+a+novel+urinary+bladder+bioreactor.">Feasibility study of a novel urinary bladder bioreactor.</a> Tissue Eng Part A. 14, 339-348 (2008).</li><li>Butcher, J. T., Nerem, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Valvular+endothelial+cells+regulate+the+phenotype+of+interstitial+cells+in+co-culture:+effects+of+steady+shear+stress.">Valvular endothelial cells regulate the phenotype of interstitial cells in co-culture: effects of steady shear stress.</a> Tissue Eng. 12, 905-915 (2006).</li><li>Metzler, S. A., Pregonero, C. A., Butcher, J. T., Burgess, S. C., Warnock, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclic+Strain+Regulates+Pro-Inflammatory+Protein+Expression+in+Porcine+Aortic+Valve+Endothelial+Cells.">Cyclic Strain Regulates Pro-Inflammatory Protein Expression in Porcine Aortic Valve Endothelial Cells.</a> J Heart Valve Dis. 17, 571-578 (2008).</li><li>Schipke, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Design of a cyclic pressure bioreactor for the ex vivo study of aortic heart valve mechanobiology. , (2008).</li><li>Smith, K. E., Metzler, S. A., Warnock, J. 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O sistema de pressão com sucesso expostos folhetos da válvula aórtica a pressões cíclicas que eram representativas de pressão transvalvar diastólica. No entanto, não foi capaz de imitar a pressão sistólica transvalvar, como a única pressão caiu para 40 mmHg. Pressão transvalvar é a diferença entre a pressão na aorta ascendente e do ventrículo esquerdo. Durante a diástole, quando a válvula é fechada, a diferença de pressão é 80mmHg em condições normotensos e 90 mmHg e 100 mmHg na fase I e hiperte...

<table border="1"><tbody><tr><th> Nome do reagente </th><th> Companhia </th><th> Número de catálogo </th><th> Comentários (opcional) </th></tr><tr><td> DMEM </td><td> Sigma </td><td> D5671 </td><td></td></tr><tr><td> PBS Dulbecco </td><td> Sigma </td><td> D5652 </td><td></td></tr><tr><td> Solução Anti-mycotic/antibiotic </td><td> Sigma </td><td> A5955 </td><td></td></tr><tr><td> Soro fetal bovino </td><td> ThermoScientific </td><td> SH30070 </td><td></td></tr><tr><td> Viton solenóide válvulas de diafragma </td><td> McMaster Carr </td><td> 4868K11 </td><td></td></tr><tr><td> Transdutor de pressão </td><td> Omega Engineering, Inc. </td><td> PX302-200GV </td><td></td></tr><tr><td> Condicionador de célula de carga </td><td> Encore Electronics, Inc. </td><td> 4025-101 </td><td></td></tr><tr><td> Módulo de Aquisição de Dados (DAQ) </td><td> Computing medição </td><td> PMD1608 </td><td></td></tr></tbody></table>

design of a cyclic pressure bioreactor for the ex vivo study of aortic heart valves

A valva aórtica, localizada entre o ventrículo esquerdo ea aorta, permite um fluxo unidirecional do sangue, impedindo o refluxo para o ventrículo. Folhetos da válvula aórtica são compostas de células intersticiais suspenso dentro de uma matriz extracelular (ECM) e são revestidas com uma monocamada de células endoteliais. A válvula resiste a um ambiente adverso e dinâmico e está constantemente exposto ao cisalhamento, flexão, tensão e compressão. A pesquisa mostrou lesões calcificadas em válvulas doentes ocorrer em áreas de alta resistência mecânica, como resultado do rompimento ou dano endotelial matriz intersticial 1-3. Por isso, não é surpreendente que estudos epidemiológicos têm demonstrado a pressão arterial elevada ser um factor de risco mais importante no aparecimento da doença da válvula aórtica 4. A única opção de tratamento atualmente disponíveis para a doença da válvula é a substituição cirúrgica da valva doente com uma válvula de prótese biológica ou mecânica 5. Melhor compreensão da biologia da válvula em resposta ao stress físico ajudaria a elucidar os mecanismos de patogênese da válvula. Por sua vez, isso poderia ajudar no desenvolvimento de terapias não invasivas, como a intervenção farmacêutica ou de prevenção. Biorreatores várias tenham sido previamente desenvolvidos para estudar a mechanobiology de válvulas cardíacas nativas ou engenharia 6-9. Biorreatores pulsátil também têm sido desenvolvidos para estudar uma variedade de tecidos, incluindo cartilagens 10, 11 e osso da bexiga 12. O objetivo deste trabalho foi desenvolver um sistema de pressão cíclica que poderia ser usado para elucidar a resposta biológica de folhetos da válvula aórtica a cargas de maior pressão. O sistema consistia de uma câmara de acrílico para colocar as amostras e produzir pressão cíclica, válvulas de diafragma viton solenóide para controlar o tempo do ciclo de pressão, e um computador para controle de dispositivos elétricos. A pressão foi monitorada através de um transdutor de pressão, eo sinal foi condicionado usando um condicionador de célula de carga. Um programa LabVIEW regulamentou a pressão utilizando um dispositivo analógico para bombear o ar comprimido para o sistema a uma taxa apropriada. O sistema imitou a dinâmica dos níveis de pressão transvalvar associado com a válvula aórtica, uma onda dente de serra produziu um aumento gradual na pressão, típico do gradiente de pressão transvalvar que está presente através da válvula durante a diástole, seguido por uma acentuada queda de pressão mostrando abertura da válvula em sístole. O programa permitiu que os usuários LabVIEW para controlar a magnitude ea freqüência de pressão cíclica. O sistema foi capaz de submeter amostras de tecido para condições de pressão fisiológicos e patológicos. Este dispositivo pode ser usado para aumentar a nossa compreensão de como válvulas cardíacas responder às mudanças no ambiente local mecânica.

Watch this Scientific Journal Video about Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves at JoVE.com

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

Um biorreator pressão cíclica capaz de submeter o tecido de válvula cardíaca em condições de pressão fisiológicos e patológicos tem sido projetado. Um programa LabVIEW permite aos usuários controlar a pressão magnitude amplitude e frequência. Este dispositivo pode ser usado para estudar a mechanobiology do tecido cardíaco válvula ou células isoladas.

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 ...

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

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15.7K visualizações.  Mississippi State University. Um biorreator pressão cíclica capaz de submeter o tecido de válvula cardíaca em condições de pressão fisiológicos e patológicos tem sido projetado. Um programa LabVIEW permite aos usuários controlar a pressão magnitude amplitude e frequência. Este dispositivo pode ser usado para estudar a mechanobiology do tecido cardíaco válvula ou células isoladas.

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

Engineering Biological-Based Vascular Grafts Using a Pulsatile Bioreactor

Much effort has been devoted to develop and advance the methodology to regenerate functional small-diameter arterial bypasses. In the physiological environment, both mechanical and chemical stimulation are required to maintain the proper development and functionality of arterial vessels1,2.
Bioreactor culture systems developed by our group are designed to support vessel regeneration within a precisely controlled chemo-mechanical environment mimicking that of native vessels. Our bioreactor assembly and maintenance procedures are fairly simple and highly repeatable3,4. Smooth muscle cells (SMCs) are seeded onto a tubular polyglycolic acid (PGA) mesh that is threaded over compliant silicone tubing and cultured in the bioreactor with or without pulsatile stimulation for up to 12 weeks. There are four main attributes that distinguish our bioreactor from some predecessors. 1) Unlike other culture systems that simulate only the biochemical surrounding of native blood vessels, our bioreactor also creates a physiological pulsatile environment by applying cyclic radial strain to the vessels in culture. 2) Multiple engineered vessels can be cultured simultaneously under different mechanical conditions within a controlled chemical environment. 3) The bioreactor allows a mono layer of endothelial cells (EC) to be easily coated onto the luminal side of engineered vessels for animal implantation models. 4) Our bioreactor can also culture engineered vessels with different diameter size ranged from 1 mm to 3 mm, saving the effort to tailor each individual bioreactor to fit a specific diameter size. 
The engineered vessels cultured in our bioreactor resemble native blood vessels histologically to some degree. Cells in the vessel walls express mature SMC contractile markers such as smooth muscle myosin heavy chain (SMMHC)3. A substantial amount of collagen is deposited within the extracellular matrix, which is responsible for ultimate mechanical strength of the engineered vessels5. Biochemical analysis also indicates that collagen content of engineered vessels is comparable to that of native arteries6. Importantly, the pulsatile bioreactor has consistently regenerated vessels that exhibit mechanical properties that permit successful implantation experiments in animal models3,7. Additionally, this bioreactor can be further modified to allow real-time assessment and tracking of collagen remodeling over time, non-invasively, using a non-linear optical microscopy (NLOM)8. To conclude, this bioreactor should serve as an excellent platform to study the fundamental mechanisms that regulate the regeneration of functional small-diameter vascular grafts.

Our group has developed a bioreactor culture system that mimics the physiological pulsatile stresses of the cardiovascular system to regenerate implantable small-diameter vascular grafts.

Engenharia Biológica Baseado em enxertos vasculares Usando um biorreator pulsátil

Much effort has been devoted to develop and advance the methodology to regenerate functional small-diameter arterial bypasses. In the physiological ...

Bioengenharia

Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of tri-leaflet polymer valve prostheses. However, identification of a protocol for initial assessment of polymer valve hydrodynamic functionality is paramount during the early stages of the design process. Traditional in vitro pulse duplicator systems are not configured to accommodate flexible tri-leaflet materials; in addition, assessment of polymer valve functionality needs to be made in a relative context to native and prosthetic heart valves under identical test conditions so that variability in measurements from different instruments can be avoided. Accordingly, we conducted hydrodynamic assessment of i) native (n = 4, mean diameter, D = 20 mm), ii) bi-leaflet mechanical (n= 2, D = 23 mm) and iii) polymer valves (n = 5, D = 22 mm) via the use of a commercially available pulse duplicator system (ViVitro Labs Inc, Victoria, BC) that was modified to accommodate tri-leaflet valve geometries. Tri-leaflet silicone valves developed at the University of Florida comprised the polymer valve group. A mixture in the ratio of 35:65 glycerin to water was used to mimic blood physical properties. Instantaneous flow rate was measured at the interface of the left ventricle and aortic units while pressure was recorded at the ventricular and aortic positions. Bi-leaflet and native valve data from the literature was used to validate flow and pressure readings. The following hydrodynamic metrics were reported: forward flow pressure drop, aortic root mean square forward flow rate, aortic closing, leakage&#160;and regurgitant volume, transaortic closing, leakage, and total energy losses. Representative results indicated that hydrodynamic metrics from the three valve groups could be successfully obtained by incorporating a custom-built assembly into a commercially available pulse duplicator system and subsequently, objectively compared to provide insights on functional aspects of polymer valve design.

There has been renewed interest in developing polymer valves. Here, the objectives are to demonstrate the feasibility of modifying a commercial pulse duplicator to accommodate tri-leaflet geometries and to define a protocol to present polymer valve hydrodynamic data in comparison to native and prosthetic valve data collected under near-identical conditions.

Protocolo Relativo Avaliação hidrodinâmica de Tri-folheto polímero Válvulas

Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of ...

Design of a Biaxial Mechanical Loading Bioreactor for Tissue Engineering

We designed a loading device that is capable of applying uniaxial or biaxial mechanical strain to a tissue engineered biocomposites fabricated for transplantation. While the device primarily functions as a bioreactor that mimics the native mechanical strains, it is also outfitted with a load cell for providing force feedback or mechanical testing of the constructs. The device subjects engineered cartilage constructs to biaxial mechanical loading with great precision of loading dose (amplitude and frequency) and is compact enough to fit inside a standard tissue culture incubator. It loads samples directly in a tissue culture plate, and multiple plate sizes are compatible with the system. The device has been designed using components manufactured for precision-guided laser applications. Bi-axial loading is accomplished by two orthogonal stages. The stages have a 50 mm travel range and are driven independently by stepper motor actuators, controlled by a closed-loop stepper motor driver that features micro-stepping capabilities, enabling step sizes of less than 50 nm. A polysulfone loading platen is coupled to the bi-axial moving platform. Movements of the stages are controlled by Thor-labs Advanced Positioning Technology (APT) software. The stepper motor driver is used with the software to adjust load parameters of frequency and amplitude of both shear and compression independently and simultaneously. Positional feedback is provided by linear optical encoders that have a bidirectional repeatability of 0.1 &mu;m and a resolution of 20 nm, translating to a positional accuracy of less than 3 &mu;m over the full 50 mm of travel. These encoders provide the necessary position feedback to the drive electronics to ensure true nanopositioning capabilities. In order to provide the force feedback to detect contact and evaluate loading responses, a precision miniature load cell is positioned between the loading platen and the moving platform. The load cell has high accuracies of 0.15% to 0.25% full scale.

We designed a novel mechanical loading bioreactor that can apply uniaxial or biaxial mechanical strain to a cartilage biocomposite prior to transplantation into an articular cartilage defect.

Projeto de um biorreator Carregando Mecânica Biaxial para Engenharia de Tecidos

We  designed a loading device that is capable of applying uniaxial or biaxial  mechanical strain to a tissue engineered biocomposites fabricated for  ...

Culturing Mouse Cardiac Valves in the Miniature Tissue Culture System

Heart valve disease is a major burden in the Western world and no effective treatment is available. This is mainly due to a lack of knowledge of the molecular, cellular and mechanical mechanisms underlying the maintenance and/or loss of the valvular structure. 
Current models used to study valvular biology include in vitro cultures of valvular endothelial and interstitial cells. Although, in vitro culturing models provide both cellular and molecular mechanisms, the mechanisms involved in the 3D-organization of the valve remain unclear. While in vivo models have provided insight into the molecular mechanisms underlying valvular development, insight into adult valvular biology is still elusive. 
In order to be able to study the regulation of the valvular 3D-organization on tissue, cellular and molecular levels, we have developed the Miniature Tissue Culture System. In this ex vivo flow model the mitral or the aortic valve is cultured in its natural position in the heart. The natural configuration and composition of the leaflet are maintained allowing the most natural response of the valvular cells to stimuli. The valves remain viable and are responsive to changing environmental conditions. This MTCS may provide advantages on studying questions including but not limited to, how does the 3D organization affect valvular biology, what factors affect 3D organization of the valve, and which network of signaling pathways regulates the 3D organization of the valve.

Here, we present an ex vivo flow model in which murine cardiac valves can be cultured allowing the study of the biology of the valve.

Cultura Rato Cardiac Valves no Sistema de Cultura de Tecidos Miniature

Heart valve disease is a major burden in the Western world and no effective treatment is available. This is mainly due to a lack of knowledge of the ...

An In Vitro Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

Various valved conduits and stent-mounted valves are used for right ventricular outflow tract (RVOT) valve replacement in patients with congenital heart disease. When using prosthetic materials however, these grafts are susceptible to bacterial infections and various host responses.
Identification of bacterial and host factors that play a vital role in endovascular adherence of microorganisms is of importance to better understand the pathophysiology of the onset of infections such as infective endocarditis (IE) and to develop preventive strategies. Therefore, the development of competent models to investigate bacterial adhesion under physiological shear conditions is necessary. Here, we describe the use of a newly designed in vitro perfusion chamber based on parallel plates that allows the study of bacterial adherence to different components of graft tissues such as exposed extracellular matrix, endothelial cells and inert areas. This method combined with colony-forming unit (CFU) counting is adequate to evaluate the propensity of graft materials towards bacterial adhesion under flow. Further on, the flow chamber system might be used to investigate the role of blood components in bacterial adhesion under shear conditions. We demonstrated that the source of tissue, their surface morphology and bacterial species specificity are not the major determining factors in bacterial adherence to graft tissues by using our in-house designed in vitro perfusion model.

An In Vitro Model of a Parallel-Plate Perfusion System to Study Bacterial Adherence to Graft Tissues

We describe an in-house designed in vitro flow chamber model, which allows the investigation of bacterial adherence to graft tissues.

Um modelo In Vitro de um sistema de perfusão paralelo-placa para estudar a aderência bacteriana para enxertar tecidos

Various valved conduits and stent-mounted valves are used for right ventricular outflow tract (RVOT) valve replacement in patients with congenital heart ...

Biologia do Desenvolvimento

A Multi-Cue Bioreactor to Evaluate the Inflammatory and Regenerative Capacity of Biomaterials under Flow and Stretch

The use of resorbable biomaterials to induce regeneration directly in the body is an attractive strategy from a translational perspective. Such materials induce an inflammatory response upon implantation, which is the driver of subsequent resorption of the material and the regeneration of new tissue. This strategy, also known as in situ tissue engineering, is pursued to obtain cardiovascular replacements such as tissue-engineered vascular grafts. Both the inflammatory and the regenerative processes are determined by the local biomechanical cues on the scaffold (i.e., stretch and shear stress). Here, we describe in detail the use of a custom-developed bioreactor that uniquely enables the decoupling of stretch and shear stress on a tubular scaffold. This allows for the systematic and standardized evaluation of the inflammatory and regenerative capacity of tubular scaffolds under the influence of well-controlled mechanical loads, which we demonstrate on the basis of a dynamic co-culture experiment using human macrophages and myofibroblasts. The key practical steps in this approach&#8212;the construction and setting up of the bioreactor, preparation of the scaffolds and cell seeding, application and maintenance of stretch and shear flow, and sample harvesting for analysis&#8212;are discussed in detail.

The goal of this protocol is to execute a dynamic co-culture of human macrophages and myofibroblasts in tubular electrospun scaffolds to investigate material-driven tissue regeneration, using a bioreactor which enables the decoupling of shear stress and cyclic stretch.

Um Bioreator multi-cue para avaliar a capacidade inflamatória e regenerativa de biomateriais sob fluxo e estiramento

The use of resorbable biomaterials to induce regeneration directly in the body is an attractive strategy from a translational perspective. Such materials ...

Engenharia

In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging

Aortic regurgitation (AR) refers to backward blood flow from the aorta into the left ventricle (LV) during ventricular diastole. The regurgitant jet arising from the complex shape is characterized by the three-dimensional flow and high-velocity gradient, sometimes limiting an accurate measurement of the regurgitant volume using 2D echocardiography. Recently developed four-dimensional flow magnetic resonance imaging (4D flow MRI) enables three-dimensional volumetric flow measurements, which can be used to accurately quantify the amount of the regurgitation. This study focuses on (i) magnetic resonance compatible AR model fabrication (dilatation, perforation, and prolapse) and (ii) systematic analysis of the performance of 4D flow MRI in AR quantification. The results indicated that the formation of the forward and backward jets over time was highly dependent on the types of AR origin. The amount of regurgitation volume bias for the model types were -7.04%, -33.21%, 6.75%, and 37.04% compared to the ground truth (48 mL) volume measured from the pump stroke volume. The largest error of the regurgitation fraction was around 12%. These results indicate that careful selection of imaging parameters is required when absolute regurgitation volume is important. The suggested in vitro flow phantom can easily be modified to simulate other valvular diseases such as aortic stenosis or bicuspid aortic valve (BAV) and can be used as a standard platform to test different MRI sequences in the future.

In vitro Assessment of Aortic Regurgitation Using Four-Dimensional Flow Magnetic Resonance Imaging

Aortic regurgitation is an aortic valve heart disease. This manuscript demonstrates how four-dimensional flow magnetic resonance imaging can evaluate aortic regurgitation using in vitro heart valves mimicking aortic regurgitation.

In vitro Avaliação da Regurgitação Aórtica usando ressonância magnética de fluxo quadridimensional

Aortic regurgitation (AR) refers to backward blood flow from the aorta into the left ventricle (LV) during ventricular diastole. The regurgitant jet ...

Designing a Bioreactor to Improve Data Acquisition and Model Throughput of Engineered Cardiac Tissues

Heart failure remains the leading cause of death worldwide, creating a pressing need for better preclinical models of the human heart. Tissue engineering is crucial for basic science cardiac research; in vitro human cell culture eliminates the interspecies differences of animal models, while a more tissue-like 3D environment (e.g., with extracellular matrix and heterocellular coupling) simulates in vivo conditions to a greater extent than traditional two-dimensional culture on plastic Petri dishes. However, each model system requires specialized equipment, for example, custom-designed bioreactors and functional assessment devices. Additionally, these protocols are often complicated, labor-intensive, and plagued by the failure of the small, delicate tissues.
This paper describes a process for generating a robust human engineered cardiac tissue (hECT) model system using induced pluripotent stem-cell-derived cardiomyocytes for the longitudinal measurement of tissue function. Six hECTs with linear strip geometry are cultured in parallel, with each hECT&#160;suspended from a pair of force-sensing polydimethylsiloxane (PDMS) posts attached to PDMS racks. Each post is capped with a black PDMS stable post tracker (SPoT), a new feature that improves the ease of use, throughput, tissue retention, and data quality. The shape allows for the reliable optical tracking of post deflections, yielding improved twitch force tracings with absolute active and passive tension. The cap geometry eliminates tissue failure due to hECTs slipping off the posts, and as they involve a second step after PDMS rack fabrication, the SPoTs can be added to existing PDMS post-based designs without major changes to the bioreactor fabrication process.
The system is used to demonstrate the importance of measuring hECT function at physiological temperatures and shows stable tissue function during data acquisition. In summary, we describe a state-of-the-art model system that reproduces key physiological conditions to advance the biofidelity, efficiency, and rigor of engineered cardiac tissues for in vitro applications.

Three-dimensional cardiac tissues bioengineered using stem-cell-derived cardiomyocytes have emerged as promising models for studying healthy and diseased human myocardium in vitro while recapitulating key aspects of the native cardiac niche. This manuscript describes a protocol for fabricating and analyzing high-content engineered cardiac tissues generated from human induced pluripotent stem-cell-derived cardiomyocytes.

Projetando um Biorreator para Melhorar a Aquisição de Dados e Modelar o Rendimento de Tecidos Cardíacos Projetados

Heart failure remains the leading cause of death worldwide, creating a pressing need for better preclinical models of the human heart. Tissue engineering ...

Um novo biorreator impresso em 3D para cultura ex vivo de vasos sanguíneos em perfusão

Ex Vivo Perfusion Culture of Large Blood Vessels in a 3D Printed Bioreactor

Vascular disease forms the basis of most cardiovascular diseases (CVDs), which remain the primary cause of mortality and morbidity worldwide. Efficacious surgical and pharmacological interventions to prevent and treat vascular disease are urgently needed. In part, the shortage of translational models limits the understanding of the cellular and molecular processes involved in vascular disease. Ex vivo perfusion culture bioreactors provide an ideal platform for the study of large animal vessels (including humans) in a controlled dynamic environment, combining the ease of in vitro culture and the complexity of the live tissue. Most bioreactors are, however, custom manufactured and therefore difficult to adopt, limiting the reproducibility of the results. This paper presents a 3D printed system that can be easily produced and applied in any biological lab, and provides a detailed protocol for its setup, enabling users&#39; operation. This innovative and reproducible ex vivo perfusion culture system enables the culture of blood vessels for up to 7 days in physiological conditions. We expect that adopting a standardized perfusion bioreactor will support a better understanding of physiological and pathological processes in large animal blood vessels and accelerate the discovery of new therapeutics.

Autor em destaque: EasyFlow - Um biorreator de perfusão econômico e adaptável para cultura de grandes vasos sanguíneos 

This protocol presents the setup and operation of a newly developed, 3D printed bioreactor for the ex vivo culture of blood vessels in perfusion. The system is designed to be easily adopted by other users, practical, affordable, and adaptable to different experimental applications, such as basic biology and pharmacological studies.

Ex Vivo Cultura de Perfusão de Grandes Vasos Sanguíneos em Biorreator Impresso em 3D

Vascular disease forms the basis of most cardiovascular diseases (CVDs), which remain the primary cause of mortality and morbidity worldwide. Efficacious ...

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

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