Este estudio fue apoyado en parte por la NASA Space Grant Nebraska y National Science Foundation con la subvención No. 0926880.

1. Preparación de la nave de látex <ol><li> Fijar ambos extremos del recipiente de látex para conexiones de las mangueras de púas, que están fijadas en un banco de trabajo robusto. </li><li> Medir el área de interés en el buque de látex para determinar el campo de visión. El área de interés para una prueba de stent debe estar centrado entre los conectores de manguera de púas e incluyen aproximadamente una pulgada a cada lado de la endoprótesis con el fin de observar las cepas pertenecientes a la zona stent. </li><li> Anotar la distancia desde el borde exterior de un conector de manguera de púas a la ubicación central entre los conectores, que es también el centro aproximado de la vasija de látex. Traducir la distancia sobre el catéter mediante la medición del centro del stent hasta el catéter. A continuación, marque el catéter con un marcador. </li><li> Retire el recipiente de látex de los conectores de manguera de púas. </li><li> Preparar el recipiente de látex por pulverización de la zona de interés con un patrón estocástico de pintura de aerosol blanco y negro o marcadoel área de interés con los puntos al azar usando un marcador permanente. Para muestras más pequeñas y el modelo estocástico más fino se requiere. </li></ol> 2. Prueba in vitro del sistema y la calibración del sistema de ARAMIS <ol><li> Seleccione el panel de calibración que es ligeramente mayor que el área de interés medido en el paso 1. </li><li> Coloque el panel de calibración entre los conectores de manguera de púas en el área de interés y asegurarse de que el área de interés está bien iluminado. </li><li> Ajuste la distancia entre dos cámaras, la distancia de la muestra, y la altura de la cámara basado en el panel de calibración seleccionado. Cada panel de calibración es diferente, por lo que el manual de usuario ARAMIS tendrá que ser consultado para determinar estas distancias. </li><li> Abra un nuevo proyecto en ARAMIS, seleccione &quot;Archivo&quot;, luego &quot;Nuevo Proyecto&quot;. Luego haga clic en el &quot;sensor&quot; y seleccione &quot;Calibración&quot;, luego &quot;Calibración completa&quot;. </li><li> El software ARAMIS ahora caminar por el usuario a través de los pasos para calibrar t<html> él las cámaras. </li><li> Con la apertura de la lente totalmente abierta, enfocar la cámara en el panel de calibración, aflojando el tornillo de ajuste de la cámara y la rotación de la lente. Una vez centrado, apretar el tornillo de fijación y cerrar la abertura. </li><li> Tomar la primera imagen del proceso de calibración. Desplazar o girar el panel de calibración de acuerdo con la demostración en el equipo, hasta que la imagen se centra en la pantalla del ordenador. Tomar la segunda imagen. Repetir este proceso para el resto de las imágenes de calibración. </li><li> Una vez que todas las imágenes de calibración se toman, el software de análisis de imagen ARAMIS calculará los ajustes de calibración. El proceso de calibración debe repetirse si la desviación de calibración es mayor que 0,04. Los ajustes realizados en el enfoque de la cámara o la distancia entre cámaras hará nulo el proceso de calibración. </li><li> Retire el panel de calibración y coloque el recipiente de látex pintado de nuevo en los conectores de manguera de púas. </li></ol>título &quot;&gt; 3. una prueba previa para evitar el ruido de fondo excesivo <ol><li> Determinar el número de cuadros por segundo que se desea para la prueba. El aumento de cuadros por segundo se producen resultados de deformación más uniformes. </li><li> Ajustar la velocidad de obturación a menos de 1 fotograma por segundo y para que ningún rojo se muestra en la imagen. </li><li> Tome 5 imágenes. </li><li> Añadir puntos de inicio de la serie de imágenes y calcular la prueba. </li><li> Mientras mantiene la tecla &quot;Ctrl&quot;, haga clic en el centro de la muestra para observar el ruido de fondo. Si el pre-test de ruido es superior al 75 microstrain el proceso de calibración debe ser hecho de nuevo. </li></ol> 4. El despliegue del stent <ol><li> Seleccione la cantidad de imágenes que desee tomar durante la prueba. 200 imágenes será suficiente para la expansión del stent. </li><li> Gradualmente insertar el catéter en el vaso de látex, y utilizando el indicador de marcador en el catéter para guiar la inserción del stent hasta que llega a la ubicación central. </li><li> Comience a tomar imágenes con Aramis. </li><li> Para el stent de globo expandible, aumenta gradualmente la presión del balón para expandir stent hasta que el globo está totalmente expandido y luego disminuye gradualmente la presión de globo a cero y se desinfla el balón y se retira junto con el catéter. </li><li> Para el stent auto-expandible, gradualmente quitar la funda hasta que el stent está totalmente expandido y luego gradualmente retraer el catéter. </li></ol> 5. Análisis Imágenes <ol><li> La cepa de la historia de un punto específico en el buque <ol><li> Crear un punto de etapa por la celebración de la tecla &quot;Ctrl&quot; y haciendo clic en el área de interés. </li><li> Seleccione el tipo de cepa que se desea, es decir, en la cepa X, Y, XY, cepa principal, cepa menor, o cepa Mises. </li><li> La parcela en la esquina inferior derecha se mostrará la tensión en el punto seleccionado sobre la duración de la prueba. </li></ol></li><li> Cepa espacial a lo largo de una ruta específica de la embarcación <ol><li> Create punto de una línea de etapas múltiples, haga clic en &quot;secciones&quot;, luego &quot;crear la sección&quot;. Seleccionar una línea en la imagen paralela al eje X en Y es igual a cero. Esto creará un número de puntos de etapa en una línea. </li><li> Después de varias etapas de la línea se crea la trama en la esquina inferior mostrará una serie de líneas en una sola trama. Cada línea representa la cepa en un caso en el tiempo a lo largo de la longitud de la sección. </li></ol></li><li> Creación de un cilindro de mejor ajuste para analizar tasa de expansión y el radio del buque <ol><li> En la barra de herramientas superior seleccione &quot;primitivos&quot;, luego &quot;cilindro de mejor ajuste&quot;. </li><li> Seleccione una sección pequeña de la imagen utilizando el &quot;seleccionar a través de la superficie&quot; de la herramienta en la barra de la derecha. </li><li> El software ARAMIS generará una tridimensional mejor ajuste del cilindro. </li><li> Las imágenes pueden ser reciclados a través de observar cómo el diámetro del vaso látex está variando. </li></ol></li><li> La evaluación de la distancia entredos puntos <ol><li> Bajo el clic de la pestaña &quot;Análisis&quot; en &quot;un punto a otro a distancia&quot;. </li><li> Seleccionar una longitud en la imagen que se desea para el análisis mediante la selección de dos puntos. </li><li> Las imágenes pueden ser reciclados a través de observar el cambio en la distancia entre los dos puntos en el tiempo. </li></ol></li></ol> 6. Los resultados representativos Los stent expanda hacia fuera la pared del vaso, las cepas generalmente será mayor en torno a la ubicación del stent. Figura 1 es un ejemplo de asignación de tensión durante el proceso de retroceso de balón expandible de stent, así como la historia cepa principal en un punto específico. Los puntos negros en la Figura 1 son puntos de referencia, que fueron utilizados por las cámaras de alta velocidad para capturar y seguir los desplazamientos de estos puntos de referencia en el conducto. Basado en el movimiento grabada de puntos de referencia, el software se utilizará entonces para calcular las cepas del conducto o unny otro objeto blanco. Cepa mayor, también conocida como la cepa principal máximo, se calcula como sigue: <img alt="Ecuación 1" src="/files/ftp_upload/3945/3945eq1.jpg" /> Es evidente que el stent implantado condujo a la distribución cepa no uniforme sobre la superficie de la vasija. Esto podría explicarse por la carga de retroceso de los extremos-constreñido conducto de látex y la estructura de malla del stent. Esta cepa de campo corresponde a la etapa inicial de retroceso del stent, como se identifica por el marcador de la cruz roja en la imagen inferior de la Figura 1. La gran tensión-la historia de la curva de un punto específico 10 demostró etapas diferenciadas de la implantación del stent. La expansión del globo se produce a partir de aproximadamente 10 a 12 segundos y de retroceso del stent tras el desinflado del balón se produce entre el 12 y 14 segundos. <img alt="Figura 1" src="/files/ftp_upload/3945/3945fig1.jpg" /> Figura 1. </strong&gt; Arreglo experimental (arriba); distribución no uniforme de la tensión en la superficie del conducto con stent (centro), la historia de gran tensión en el punto 10 (abajo).

<ol>
	<li>Fischman, D. L., Leon, M. B., Baim, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+randomized+comparison+of+coronary-stent+placement+and+balloon+angioplasty+in+the+treatment+of+coronary+artery+disease.+Stent+Restenosis+Study+Investigators.">A randomized comparison of coronary-stent placement and balloon angioplasty in the treatment of coronary artery disease. Stent Restenosis Study Investigators.</a> N. Engl. J. Med. 331, 496-501 (1994).</li><li>Abul Hasan Muhammad Bashar, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+Properties+of+Various+Z-Stent+Designs:+An+Endovascular+Stent-Grafting+Perspective.">Mechanical Properties of Various Z-Stent Designs: An Endovascular Stent-Grafting Perspective.</a> Artificial Organs. 27, 714-721 (2003).</li><li>Nuutinen, J. u. h. a. -. P. e. k. k. a. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+properties+and+in+vitro+degradation+of+bioabsorbable+self-expanding+braided+stents.">Mechanical properties and in vitro degradation of bioabsorbable self-expanding braided stents.</a> Journal of Biomaterials Science -- Polymer Edition. , 255-266 (2003).</li><li>C. Schulz, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coronary+stent+symmetry+and+vascular+injury+determine+experimental+restenosis.">Coronary stent symmetry and vascular injury determine experimental restenosis.</a> Heart. 83, 462-467 (2000).</li><li>Jiménez, J. M., Davies, P. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemodynamically+Driven+Stent+Strut+Design.">Hemodynamically Driven Stent Strut Design.</a> Annals of Biomedical Engineering. 1483, (2009).</li><li>Johnston, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Mechanical+Properties+of+Endovascular+Stents:+An+In+Vitro+Assessment.">The Mechanical Properties of Endovascular Stents: An In Vitro Assessment.</a> Cardiovascular Engineering: An International Journal. 10, 128-135 (2010).</li><li>Mejia, J. u. a. n. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+the+effect+of+stent+strut+profile+on+shear+stress+distribution+using+statistical+moments.">Evaluation of the effect of stent strut profile on shear stress distribution using statistical moments.</a> Biomedical Engineering Online. , 1-10 (2009).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> ARAMIS User Manual. , (2009).</li><li>Chesler, N. C., Thompson-Figueroa, J., Millburne, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurements+of+Mouse+Pulmonary+Biomechanics.">Measurements of Mouse Pulmonary Biomechanics.</a> Journal of Biomechanical Engineering. 126, 309-314 (2004).</li><li>de Korte, C. L., Sierevogel, M. J., Mastik, F., Strijder, C., Schaar, J. A., Velema, E., Pasterkamp, G., Serruys, P. W., van der Steen, A. F. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+Atherosclerotic+Plaque+Components+With+Intravascular+Ultrasound+Elastography+In+Vivo+A+Yucatan+Pig+Study.">Identification of Atherosclerotic Plaque Components With Intravascular Ultrasound Elastography In Vivo A Yucatan Pig Study.</a> Circulation. 105, 1627-1630 (2002).</li></ol>

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El estéreo tensión óptica superficie sistema de medición se usa para medir las tensiones locales sobre la superficie deformando tanto para los dentro y fuera del plano movimientos sin contacto con el espécimen. Este sistema utiliza dos cámaras de alta velocidad ópticos para tomar imágenes de un patrón aleatorio contrastantes poner en la superficie para construir mediciones precisas de los movimientos de cada punto, con una alta precisión de resolver las cepas de superficie. Cabe se...

<table border="1"><tbody><tr><td> Equipo usado </td><td> Empresa </td><td> Número de catálogo </td><td> Comentarios </td></tr><tr><td> ARAMIS sistema de cámara </td><td> GOM: técnicas de medición óptica </td><td></td><td></td></tr><tr><td> PALMAZ Génesis STENT biliar transhepático </td><td> Cordis Corporation </td><td> PG5910B </td><td> Stent de globo expandible </td></tr><tr><td> Z-MED catéter de dilatación con balón </td><td> B. Braun Medical Inc. </td><td> PDZ336 </td><td> Catéter de dilatación con balón </td></tr></tbody></table>

monitoring the wall mechanics during stent deployment in a vessel

Los ensayos clínicos han reportado tasas de reestenosis diferentes para diferentes diseños de stent 1. Se especula que el stent inducidos por las concentraciones de tensión en la pared arterial conducen a la lesión tisular, que inicia la reestenosis 2-7. Esta hipótesis necesita investigaciones adicionales, como la mejor cuantificación de la distribución de la tensión no uniforme sobre la arteria después de la implantación del stent. Un no-contacto deformación superficial método de medición de la arteria con stent se presenta en este trabajo. ARAMIS estéreo superficie óptica cepa sistema de medición utiliza dos cámaras ópticas de alta velocidad para capturar el movimiento de cada punto de referencia, y resolver las tres cepas de dimensiones sobre la superficie de deformación de 8,9. Como un stent de malla se implementa en un recipiente de látex con un patrón aleatorio contrastante rociado o dibujado en su superficie exterior, la cepa superficie está grabada en cada instante de la deformación. Las distribuciones de deformación calculados a continuación, se puede utilizar para entender la LOrespuesta de cal lesión, validar los modelos computacionales, y formular hipótesis para ulterior estudio in vivo.

Watch this Scientific Journal Video about Monitoring the Wall Mechanics During Stent Deployment in a Vessel at JoVE.com

Monitoring the Wall Mechanics During Stent Deployment in a Vessel

Stent inducidas distribuciones de tensión arterial se caracterizan mediante una tensión óptica superficie sistema de medición. Esta técnica de visualización se utiliza para obtener información sobre el impacto de la implantación de un stent en el vaso receptor.

El seguimiento de los mecánica de la pared durante la implementación del stent en un buque

Clinical trials have reported different restenosis rates for various stent designs1. It is speculated that stent-induced strain concentrations on the ...

monitoring-the-wall-mechanics-during-stent-deployment-in-a-vessel

Research

JoVE Journal

Bioengineering

9.2K vistas.  University of Nebraska-Lincoln. Stent inducidas distribuciones de tensión arterial se caracterizan mediante una tensión óptica superficie sistema de medición. Esta técnica de visualización se utiliza para obtener información sobre el impacto de la implantación de un stent en el vaso receptor.

Video: Monitoring the Wall Mechanics During Stent Deployment in a Vessel

Magnetic Resonance Elastography Methodology for the Evaluation of Tissue Engineered Construct Growth

Traditional mechanical testing often results in the destruction of the sample, and in the case of long term tissue engineered construct studies, the use of destructive assessment is not acceptable. A proposed alternative is the use of an imaging process called magnetic resonance elastography. Elastography is a nondestructive method for determining the engineered outcome by measuring local mechanical property values (i.e., complex shear modulus), which are essential markers for identifying the structure and functionality of a tissue. As a noninvasive means for evaluation, the monitoring of engineered constructs with imaging modalities such as magnetic resonance imaging (MRI) has seen increasing interest in the past decade1. For example, the magnetic resonance (MR) techniques of diffusion and relaxometry have been able to characterize the changes in chemical and physical properties during engineered tissue development2. The method proposed in the following protocol uses microscopic magnetic resonance elastography (&mu;MRE) as a noninvasive MR based technique for measuring the mechanical properties of small soft tissues3. MRE is achieved by coupling a sonic mechanical actuator with the tissue of interest and recording the shear wave propagation with an MR scanner4. Recently, &mu;MRE has been applied in tissue engineering to acquire essential growth information that is traditionally measured using destructive mechanical macroscopic techniques5. In the following procedure, elastography is achieved through the imaging of engineered constructs with a modified Hahn spin-echo sequence coupled with a mechanical actuator. As shown in Figure 1, the modified sequence synchronizes image acquisition with the transmission of external shear waves; subsequently, the motion is sensitized through the use of oscillating bipolar pairs. Following collection of images with positive and negative motion sensitization, complex division of the data produce a shear wave image. Then, the image is assessed using an inversion algorithm to generate a shear stiffness map6. The resulting measurements at each voxel have been shown to strongly correlate (R2&gt;0.9914) with data collected using dynamic mechanical analysis7. In this study, elastography is integrated into the tissue development process for monitoring human mesenchymal stem cell (hMSC) differentiation into adipogenic and osteogenic constructs as shown in Figure 2.

The procedure demonstrates the methodology of magnetic resonance elastography for monitoring the engineered outcome of adipose and osteogenic tissue engineered constructs through noninvasive local assessment of the mechanical properties using microscopic magnetic resonance elastography (&mu;MRE).

Metodología elastografía por resonancia magnética para la Evaluación de los tejidos Diseñado crecimiento Construct

Traditional mechanical testing often results in the destruction of the sample, and in the case of long term tissue engineered construct studies, the use ...

Investigación

Bioingeniería

Mass Cytometry: Protocol for Daily Tuning and Running Cell Samples on a CyTOF Mass Cytometer

In recent years, the rapid analysis of single cells has commonly been performed using flow cytometry and fluorescently-labeled antibodies. However, the issue of spectral overlap of fluorophore emissions has limited the number of simultaneous probes. In contrast, the new CyTOF mass cytometer by DVS Sciences couples a liquid single-cell introduction system to an ICP-MS.1 Rather than fluorophores, chelating polymers containing highly-enriched metal isotopes are coupled to antibodies or other specific probes.2-5 Because of the metal purity and mass resolution of the mass cytometer, there is no "spectral overlap" from neighboring isotopes, and therefore no need for compensation matrices. Additionally, due to the use of lanthanide metals, there is no biological background and therefore no equivalent of autofluorescence. With a mass window spanning atomic mass 103-203, theoretically up to 100 labels could be distinguished simultaneously. Currently, more than 35 channels are available using the chelating reagents available from DVS Sciences, allowing unprecedented dissection of the immunological profile of samples.6-7
Disadvantages to mass cytometry include the strict requirement for a separate metal isotope per probe (no equivalent of forward or side scatter), and the fact that it is a destructive technique (no possibility of sorting recovery). The current configuration of the mass cytometer also has a cell transmission rate of only ~25%, thus requiring a higher input number of cells.
Optimal daily performance of the mass cytometer requires several steps. The basic goal of the optimization is to maximize the measured signal intensity of the desired metal isotopes (M) while minimizing the formation of oxides (M+16) that will decrease the M signal intensity and interfere with any desired signal at M+16. The first step is to warm up the machine so a hot, stable ICP plasma has been established. Second, the settings for current and make-up gas flow rate must be optimized on a daily basis. During sample collection, the maximum cell event rate is limited by detector efficiency and processing speed to 1000 cells/sec. However, depending on the sample quality, a slower cell event rate (300-500 cells/sec) is usually desirable to allow better resolution between cells events and thus maximize intact singlets over doublets and debris. Finally, adequate cleaning of the machine at the end of the day helps minimize background signal due to free metal.

The steps necessary for daily tuning and optimization of the performance of a CyTOF mass cytometer are described. Comments on optimal sample preparation and flow rate are discussed

Citometría de masas: Protocolo para la afinación y servicio diario muestras de células en un citómetro de masas CyTOF

In recent years, the rapid analysis of single cells has commonly been performed using flow cytometry and fluorescently-labeled antibodies. However, the ...

A Versatile Automated Platform for Micro-scale Cell Stimulation Experiments

Study of cells in culture (in vitro analysis) has provided important insight into complex biological systems. Conventional methods and equipment for in vitro analysis are well suited to study of large numbers of cells (&ge;105) in milliliter-scale volumes (&ge;0.1 ml). However, there are many instances in which it is necessary or desirable to scale down culture size to reduce consumption of the cells of interest and/or reagents required for their culture, stimulation, or processing. Unfortunately, conventional approaches do not support precise and reproducible manipulation of micro-scale cultures, and the microfluidics-based automated systems currently available are too complex and specialized for routine use by most laboratories. To address this problem, we have developed a simple and versatile technology platform for automated culture, stimulation, and recovery of small populations of cells (100 - 2,000 cells) in micro-scale volumes (1 - 20 &mu;l). The platform consists of a set of fibronectin-coated microcapillaries ("cell perfusion chambers"), within which micro-scale cultures are established, maintained, and stimulated; a digital microfluidics (DMF) device outfitted with "transfer" microcapillaries ("central hub"), which routes cells and reagents to and from the perfusion chambers; a high-precision syringe pump, which powers transport of materials between the perfusion chambers and the central hub; and an electronic interface that provides control over transport of materials, which is coordinated and automated via pre-determined scripts. As an example, we used the platform to facilitate study of transcriptional responses elicited in immune cells upon challenge with bacteria. Use of the platform enabled us to reduce consumption of cells and reagents, minimize experiment-to-experiment variability, and re-direct hands-on labor. Given the advantages that it confers, as well as its accessibility and versatility, our platform should find use in a wide variety of laboratories and applications, and prove especially useful in facilitating analysis of cells and stimuli that are available in only limited quantities.

We have developed an automated cell culture and interrogation platform for micro-scale cell stimulation experiments. The platform offers simple, versatile, and precise control in cultivating and stimulating small populations of cells, and recovering lysates for molecular analyses. The platform is well suited to studies that use precious cells and/or reagents.

Una plataforma automatizada versátil para Micro escala experimentos de estimulación celular

Study of cells in culture (in vitro analysis) has provided important insight into complex biological systems. Conventional methods and equipment for in ...

Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180&#176; Curved Artery Test Section

The arterial network in the human vasculature comprises of ubiquitously present blood vessels with complex geometries (branches, curvatures and tortuosity). Secondary flow structures are vortical flow patterns that occur in curved arteries due to the combined action of centrifugal forces, adverse pressure gradients and inflow characteristics. Such flow morphologies are greatly affected by pulsatility and multiple harmonics of physiological inflow conditions and vary greatly in size-strength-shape characteristics compared to non-physiological (steady and oscillatory) flows 1 - 7.
Secondary flow structures may ultimately influence the wall shear stress and exposure time of blood-borne particles toward progression of atherosclerosis, restenosis, sensitization of platelets and thrombosis 4 - 6, 8 - 13. Therefore, the ability to detect and characterize these structures under laboratory-controlled conditions is precursor to further clinical investigations.
A common surgical treatment to atherosclerosis is stent implantation, to open up stenosed arteries for unobstructed blood flow. But the concomitant flow perturbations due to stent installations result in multi-scale secondary flow morphologies 4 - 6. Progressively higher order complexities such as asymmetry and loss in coherence can be induced by ensuing stent failures vis-&#224;-vis those under unperturbed flows 5. These stent failures have been classified as &#34;Types I-to-IV&#34; based on failure considerations and clinical severity 14.
This study presents a protocol for the experimental investigation of the complex secondary flow structures due to complete transverse stent fracture and linear displacement of fractured parts (&#34;Type IV&#34;) in a curved artery model. The experimental method involves the implementation of particle image velocimetry (2C-2D PIV) techniques with an archetypal carotid artery inflow waveform, a refractive index matched blood-analog working fluid for phase-averaged measurements 15 - 18. Quantitative identification of secondary flow structures was achieved using concepts of flow physics, critical point theory and a novel wavelet transform algorithm applied to experimental PIV data 5, 6, 19 - 26.

Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180&amp;#176; Curved Artery Test Section

Stent implants in stenosed arterial curvatures are prone to "Type IV" failures involving the complete transverse fracture of stents and linear displacement of the fractured parts. We present a protocol for detection of secondary flow (vortical) structures in a curved artery model, downstream of clinically relevant "Type IV" stent failures.

Investigación experimental de estructuras secundarias de flujo aguas abajo de una Falla Modelo Tipo IV stent en una sección de prueba 180 ° de la arteria curvada

The arterial network in the human vasculature comprises of ubiquitously present blood vessels with complex geometries (branches, curvatures and ...

Adapting the Electrospinning Process to Provide Three Unique Environments for a Tri-layered In Vitro Model of the Airway Wall

Electrospinning is a highly adaptable method producing porous 3D fibrous scaffolds that can be exploited in in vitro cell culture. Alterations to intrinsic parameters within the process allow a high degree of control over scaffold characteristics including fiber diameter, alignment and porosity. By developing scaffolds with similar dimensions and topographies to organ- or tissue-specific extracellular matrices (ECM), micro-environments representative to those that cells are exposed to in situ can be created. 
The airway bronchiole wall, comprised of three main micro-environments, was selected as a model tissue. Using decellularized airway ECM as a guide, we electrospun the non-degradable polymer, polyethylene terephthalate (PET), by three different protocols to produce three individual electrospun scaffolds optimized for epithelial, fibroblast or smooth muscle cell-culture. Using a commercially available bioreactor system, we stably co-cultured the three cell-types to provide an in vitro model of the airway wall over an extended time period.
This model highlights the potential for such methods being employed in in vitro diagnostic studies investigating important inter-cellular cross-talk mechanisms or assessing novel pharmaceutical targets, by providing a relevant platform to allow the culture of fully differentiated adult cells within 3D, tissue-specific environments.

Adapting the Electrospinning Process to Provide Three Unique Environments for a Tri-layered In Vitro Model of the Airway Wall

Advancements in biomaterial technologies enable the development of three-dimensional multi-cell-type constructs. We have developed electrospinning protocols to produce three individual scaffolds to culture the main structural cells of the airway to provide a 3D in vitro model of the airway bronchiole wall.

Adaptación del Proceso Electrohilado para proporcionar tres ambientes únicos para un Tri-capa<em&gt; In Vitro</em&gt; Modelo de la pared de la vía aérea

Electrospinning is a highly adaptable method producing porous 3D fibrous scaffolds that can be exploited in in vitro cell culture. Alterations to ...

Ferromagnetic Bare Metal Stent for Endothelial Cell Capture and Retention

Rapid endothelialization of cardiovascular stents is needed to reduce stent thrombosis and to avoid anti-platelet therapy which can reduce bleeding risk. The feasibility of using magnetic forces to capture and retain endothelial outgrowth cells (EOC) labeled with super paramagnetic iron oxide nanoparticles (SPION) has been shown previously. But this technique requires the development of a mechanically functional stent from a magnetic and biocompatible material followed by in-vitro and in-vivo testing to prove rapid endothelialization. We developed a weakly ferromagnetic stent from 2205 duplex stainless steel using computer aided design (CAD) and its design was further refined using finite element analysis (FEA). The final design of the stent exhibited a principal strain below the fracture limit of the material during mechanical crimping and expansion. One hundred stents were manufactured and a subset of them was used for mechanical testing, retained magnetic field measurements, in-vitro cell capture studies, and in-vivo implantation studies. Ten stents were tested for deployment to verify if they sustained crimping and expansion cycle without failure. Another 10 stents were magnetized using a strong neodymium magnet and their retained magnetic field was measured. The stents showed that the retained magnetism was sufficient to capture SPION-labeled EOC in our in-vitro studies. SPION-labeled EOC capture and retention was verified in large animal models by implanting 1 magnetized stent and 1 non-magnetized control stent in each of 4 pigs. The stented arteries were explanted after 7 days and analyzed histologically. The weakly magnetic stents developed in this study were capable of attracting and retaining SPION-labeled endothelial cells which can promote rapid healing.

Our goals were to design, manufacture and test ferromagnetic stents for endothelial cell capture. Ten stents were tested for fracture and 10 more stents were tested for retained magnetism. Finally, 10 stents were tested in-vitro and 8 more stents were implanted in 4 pigs to show cell capture and retention.

Ferromagnético Bare Metal stent para la captura de la célula endotelial y Retención

Rapid endothelialization of cardiovascular stents is needed to reduce stent thrombosis and to avoid anti-platelet therapy which can reduce bleeding risk. ...

Mammalian Cell Encapsulation in Alginate Beads Using a Simple Stirred Vessel

Cell encapsulation in alginate beads has been used for immobilized cell culture in vitro as well as for immunoisolation in vivo. Pancreatic islet encapsulation has been studied extensively as a means to increase islet survival in allogeneic or xenogeneic transplants. Alginate encapsulation is commonly achieved by nozzle extrusion and external gelation. Using this method, cell-containing alginate droplets formed at the tip of nozzles fall into a solution containing divalent cations that cause ionotropic alginate gelation as they diffuse into the droplets. The requirement for droplet formation at the nozzle tip limits the volumetric throughput and alginate concentration that can be achieved. This video describes a scalable emulsification method to encapsulate mammalian cells in 0.5% to 10% alginate with 70% to 90% cell survival. By this alternative method, alginate droplets containing cells and calcium carbonate are emulsified in mineral oil, followed by a decrease in pH leading to internal calcium release and ionotropic alginate gelation. The current method allows the production of alginate beads within 20 min of emulsification. The equipment required for the encapsulation step consists in simple stirred vessels available to most laboratories.

This video and manuscript describe an emulsion-based method to encapsulate mammalian cells in 0.5% to 10% alginate beads which can be produced in large batches using a simple stirred vessel. The encapsulated cells can be cultured in vitro or transplanted for cellular therapy applications.

Encapsulación de células de mamífero en perlas de alginato usando un recipiente agitador simple

Cell encapsulation in alginate beads has been used for immobilized cell culture in vitro as well as for immunoisolation in vivo. Pancreatic islet ...

Simulating the Mechanics of Lens Accommodation via a Manual Lens Stretcher

The goal of this protocol is to mimic the biomechanics of physiological accommodation in a cost-efficient, practical manner. Accommodation is achieved through the contraction of the ciliary body and relaxation of zonule fibers, which results in the thickening of the lens necessary for near vision. Here, we present a novel, simple method in which accommodation is replicated by tensing the zonules connected to the lens capsule via a manual lens stretcher (MLS). This method monitors the radial stretching achieved by a lens when subjected to a consistent force and allows for a comparison of accommodating lenses, which can be stretched, to non-accommodating lenses, which cannot be stretched. Importantly, the stretcher couples to the zonules directly, and not to the sclera of the eye, thus only requiring the lens, zonules, and ciliary body rather than the entire globe sample. This difference can significantly decrease the cost of acquiring donor cadaver lenses by about 62% compared to acquiring an entire globe.

We present an efficient method of studying lens accommodation by using a manual lens stretcher. The protocol mimics physiological accommodation by pulling the zonules connected around the lens capsule, thereby, stretching the lens.

Simulación de la mecánica del alojamiento de la lente a través de una camilla de lente Manual

The goal of this protocol is to mimic the biomechanics of physiological accommodation in a cost-efficient, practical manner. Accommodation is achieved ...

Nondestructive Monitoring of Degradable Scaffold-Based Tissue-Engineered Blood Vessel Development Using Optical Coherence Tomography

Engineered vascular grafts with structural and mechanical properties similar to natural blood vessels are expected to meet the growing demand for arterial bypass. Characterization of the growth dynamics and remodeling process of degradable polymer scaffold-based tissue-engineered blood vessels (TEBVs) with pulsatile stimulation is crucial for vascular tissue engineering. Optical imaging techniques stand out as powerful tools for monitoring vascularization of engineered tissue enabling high-resolution imaging in real-time culture. This paper demonstrates a nondestructive and fast real-time imaging strategy to monitor the growth and remodeling of TEBVs in long-term culture by using optical coherence tomography (OCT). Geometric morphology is evaluated, including vascular remodeling process, wall thickness, and comparison of TEBV thickness in different culture time points and presence of pulsatile stimulation. Finally, OCT provides practical possibilities for real-time observation of the degradation of polymer in the reconstructing tissues under pulsatile stimulation or not and in each vessel segment, by compared with the assessment of polymer degradation using scanning electron microscopic(SEM) and polarized microscope.

A step by step protocol for nondestructive and long-period monitoring the process of vascular remodeling and scaffold degradation in real-time culture of biodegradable polymeric scaffold-based tissue-engineered blood vessels with pulsatile stimulation using optical coherence tomography is described here.

Monitoreo no destructivos del desarrollo Degradable andamio base ingeniería de tejido vascular mediante tomografía de coherencia óptica

Engineered vascular grafts with structural and mechanical properties similar to natural blood vessels are expected to meet the growing demand for arterial ...

Patterning the Geometry of Human Embryonic Stem Cell Colonies on Compliant Substrates to Control Tissue-Level Mechanics

Human embryonic stem cells demonstrate a unique ability to respond to morphogens in vitro by self-organizing patterns of cell fate specification that correspond to primary germ layer formation during embryogenesis. Thus, these cells represent a powerful tool with which to examine the mechanisms that drive early human development. We have developed a method to culture human embryonic stem cells in confined colonies on compliant substrates that provides control over both the geometry of the colonies and their mechanical environment in order to recapitulate the physical parameters that underlie embryogenesis. The key feature of this method is the ability to generate polyacrylamide hydrogels with defined patterns of extracellular matrix ligand at the surface to promote cell attachment. This is achieved by fabricating stencils with the desired geometric patterns, using these stencils to create patterns of extracellular matrix ligand on glass coverslips, and transferring these patterns to polyacrylamide hydrogels during polymerization. This method is also compatible with traction force microscopy, allowing the user to measure and map the distribution of cell-generated forces within the confined colonies. In combination with standard biochemical assays, these measurements can be used to examine the role mechanical cues play in fate specification and morphogenesis during early human development.

Extracellular matrix ligands can be patterned onto polyacrylamide hydrogels to enable the culture of human embryonic stem cells in confined colonies on compliant substrates. This method can be combined with traction force microscopy and biochemical assays to examine the interplay between tissue geometry, cell-generated forces, and fate specification.

Patrón de la geometría de las colonias de células madre embrionarias humanas en sustratos compatibles para controlar la mecánica de nivel de tejido

Human embryonic stem cells demonstrate a unique ability to respond to morphogens in vitro by self-organizing patterns of cell fate specification that ...