Les auteurs sont reconnaissants à Shad Schipke et Daniel Chesser pour leur aide à la conception et la fabrication du système et Myles Valtresa de l&#39;aide pour la préparation du manuscrit.

1. Récolte et préparation des tissus <ol><li> Valves aortiques doivent être prélevés sur des porcs adultes pesant pas plus de £ 120 immédiatement après la mort. </li><li> Lavez les vannes à deux reprises avec une solution saline tamponnée phosphate stérile (PBS) et le transport au laboratoire sur la glace. </li><li> Toutes les étapes suivantes devraient être effectuées dans des conditions stériles. </li><li> Assurez-vous que des tracts ne montrent aucun signe de dégénérescence, déchirure ou de calcification. Retirer des tracts de la racine aortique en coupant 1 / 3 de la distance de l&#39;anneau. </li><li> Placez des dépliants dans les puits individuels d&#39;une plaque de six puits et incuber pendant la nuit avec 3ml de Dulbecco Modified Eagle Médium complété avec une solution anti-biotic/anti-mycotic 1% et 10% de sérum fœtal bovin à 37 ° C et 5% de CO 2. </li><li> Comme alternative, les cellules isolées peuvent être ensemencées dans des plaques de culture à six puits et utilisée dans le dispositif de pression. L&#39;isolement des cellules endothéliales et les cellules de soupape interstitielle peut être effectuée comme décrit précédemment 13, 14. </li></ol> 2. Les études de pression <ol><li> Un système de pression faits sur mesure a été conçu pour étudier les effets de la pression cyclique mécanobiologique sur le tissu de la valve aortique 15. </li><li> Connectez-vous à l&#39;ordinateur et ouvrez le programme LabVIEW (Figure 1). </li><li> Calibrage: <ol><li> Avant l&#39;expérimentation, le système doit être correctement étalonné. </li><li> Branchez l&#39;alimentation sur le circuit. Ceci fournit la puissance aux électrovannes qui contrôlent le flux d&#39;air entrant et sortant de la chambre. </li><li> Assurez-vous que l&#39;air comprimé est connecté au système et ouvrir l&#39;alimentation en air à la vitesse plein. </li><li> Allumez l&#39;amplificateur de signal. Assurez-vous que la lecture de tension est de 0,00. Ajustez si nécessaire </li><li> L&#39;interface LabVIEW a un commutateur marqué «TEST / RECORD&quot;. Assurez-vous que le commutateur est réglé sur &quot;TEST&quot;. Cliquez sur le bouton marqué &quot;Air Supply&quot; pour ouvrir l&#39;électrovanne d&#39;admission. </li><li> En utilisant le régulateur de pression de gaz, sous pression de la chambre à air comprimé à 1 PSI. La pression dans la chambre peut être lu en utilisant le manomètre numérique situé à l&#39;arrière plaque d&#39;extrémité de la chambre. Une fois que la pression a équilibré, d&#39;enregistrer la lecture de tension de l&#39;amplificateur de signal. Répétez l&#39;opération pour PSI 2, 3, 4 et 5. </li><li> Construire une courbe d&#39;étalonnage de pression fonction de la tension. La pression doit être converti à partir PSI mmHg. L&#39;équation à partir du graphique peuvent être placés dans le code du programme LabVIEW </li></ol></li><li> Retirez la plaque avant en aluminium de la chambre de pression et de pulvérisation de la chambre avec 70% d&#39;éthanol. Laisser un minimum de 10 minutes pour permettre à des vapeurs d&#39;éthanol résiduel se dissipe. </li><li> Placer la plaque de six puits contenant les échantillons dépliant dans la chambre et de remplacer la plaque frontale. S&#39;assurer que le joint est étanche par serrage des écrous situés sur les quatre tiges filetées (situés à chaque coin de la plaque d&#39;extrémité) à la main. Placez la chambre de pression dans l&#39;incubateur 37 ° C. Un diagramme schématique de la chambre de pression est montré dans la figure 2. </li><li> L&#39;interface invite l&#39;utilisateur à fournir la quantité de temps entre les cycles du système d&#39;air comprimé d&#39;entrée et de sortie. Ceux-ci devraient être mis à 0.6s et 0.4s pour imiter les conditions systolique et diastolique, respectivement, à une fréquence de 1Hz. L&#39;utilisateur doit également entrer un chemin vers le fichier de données. </li><li> Dans LabVIEW, cliquez sur Exécuter et passer le «TEST / RECORD&quot; toggle pour &quot;enregistrer&quot;. </li><li> Assurez-vous que la pression est au niveau souhaité à l&#39;aide du graphique de l&#39;interface LabVIEW. La pression peut être ajustée en utilisant le régulateur de pression de gaz. </li><li> Exécutez le programme pour la longueur de temps désirée. </li><li> Une fois l&#39;expérience terminée, cliquez sur le bouton d&#39;arrêt sur LabVIEW, éteignez l&#39;alimentation en air et d&#39;ouvrir la soupape d&#39;échappement sur la chambre de pression. </li><li> Retirer la plaque d&#39;extrémité avant de la chambre et récupérer des échantillons de plaque de six puits contenant. Les échantillons peuvent maintenant être analysées pour l&#39;expression des gènes, l&#39;expression des protéines, l&#39;histologie, les propriétés mécaniques etc </li></ol> 3. Les résultats représentatifs: Le système de pression est capable de simuler les pressions maximales observées sous transvalvulaire normotendus, de phase I et II des conditions hypertendus. Cependant, la pression n&#39;a pas été capable d&#39;imiter le gradient de pression systolique, qui est essentiellement nul in vivo. Fréquence est maintenue à 1Hz, avec un temps d&#39;entrée d&#39;air de 0,6 s et un temps d&#39;échappement de 0,4 s. Courbes de pression représentant des conditions de pression normales et élevées obtenues par le système peut être vu dans la figure 3. <img src="/files/ftp_upload/3316/3316fig1.jpg" alt="Figure 1"/> Figure 1: Capture d&#39;écran de l&#39;interface LabVIEW. <img src="/files/ftp_upload/3316/3316fig2.jpg" alt="Figure 2"/> Figure 2: Schéma de la vue la pression chambre A. isométrique de la chambre de pression; B. Vue latérale de la chambre de pression;C. Vue du haut de la chambre de pression. <img src="/files/ftp_upload/3316/3316fig3.jpg" alt="Figure 3"/> Figure 3: Graphe de simulation de pression dans la chambre de pression en (A) normotendus, (B) Stade I hypertendus, et (C) Phase II des conditions hypertendus.

<ol>
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K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+and+physical+characterization+of+a+synchronous+multivalve+aortic+valve+culture+system.">Design and physical characterization of a synchronous multivalve aortic valve culture system.</a> Ann Biomed Eng. 38, 319-3125 (2010).</li><li>Engelmayr, G. C., Soletti, L., Vigmostad, S. C., Budilarto, S. G., Federspiel, W. J., Chandran, K. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+flex-stretch-flow+bioreactor+for+the+study+of+engineered+heart+valve+tissue+mechanobiology.">A novel flex-stretch-flow bioreactor for the study of engineered heart valve tissue mechanobiology.</a> Ann Biomed Eng. 36, 700-712 (2008).</li><li>Sucosky, P., Padala, M., Elhammali, A., Balachandran, K., Jo, H., Yoganathan, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Design+of+an+ex+vivo+culture+system+to+investigate+the+effects+of+shear+stress+on+cardiovascular+tissue.">Design of an ex vivo culture system to investigate the effects of shear stress on cardiovascular tissue.</a> J Biomech Eng. 130, 035001-03 (2008).</li><li>Syedain, Z. H., Tranquillo, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+cyclic+stretch+bioreactor+for+tissue-engineered+heart+valves.">Controlled cyclic stretch bioreactor for tissue-engineered heart valves.</a> Biomaterials. 30, 4078-4084 (2009).</li><li>Lagana, K., Moretti, M., Dubini, G., Raimondi, M. 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Aucun conflit d&#39;intérêt déclaré.

Le système de pression avec succès exposés tracts valve aortique à des pressions cycliques qui sont représentatifs de la pression diastolique transvalvulaire. Toutefois, il n&#39;a pas été capable d&#39;imiter la pression systolique transvalvulaire, comme la seule pression a chuté à 40 mmHg. Pression transvalvulaire est la différence entre la pression dans l&#39;aorte ascendante et le ventricule gauche. Pendant la diastole, lorsque le clapet est fermé, la différence de pression est 80mmHg dans des conditions...

<table border="1"><tbody><tr><th> Nom du réactif </th><th> Société </th><th> Numéro de catalogue </th><th> Commentaires (optionnel) </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> Solution Anti-mycotic/antibiotic </td><td> Sigma </td><td> A5955 </td><td></td></tr><tr><td> Sérum de veau fœtal </td><td> ThermoScientific </td><td> SH30070 </td><td></td></tr><tr><td> Vannes à membrane Viton électrovanne </td><td> McMaster Carr </td><td> 4868K11 </td><td></td></tr><tr><td> Capteur de pression </td><td> Omega Engineering, Inc </td><td> PX302-200GV </td><td></td></tr><tr><td> Conditionneur de cellule de charge </td><td> Encore Electronics, Inc </td><td> 4025-101 </td><td></td></tr><tr><td> Acquisition de données (DAQ) Module </td><td> Measurement Computing </td><td> PMD1608 </td><td></td></tr></tbody></table>

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

La valve aortique, situé entre le ventricule gauche et l&#39;aorte, permet la circulation sanguine unidirectionnelle, en prévenant le refoulement dans le ventricule. Des tracts de la valve aortique sont composés de cellules interstitielles en suspension dans une matrice extracellulaire (MEC) et sont bordées d&#39;une monocouche de cellules endothéliales. La vanne résiste à un environnement difficile et dynamique et est constamment exposée à de cisaillement, de flexion, la tension et de compression. La recherche a montré des lésions calcifiées dans les valves malades se produisent dans les zones de fortes contraintes mécaniques en raison de perturbations ou dommages endothéliales matrice interstitielle 1-3. Par conséquent, il n&#39;est pas surprenant que les études épidémiologiques ont montré une pression artérielle élevée est un facteur de risque important dans l&#39;apparition de la maladie de valve aortique 4. La seule option de traitement actuellement disponibles pour la maladie de valve est le remplacement chirurgical de la valve malade par une valve mécanique ou bioprothèse 5. Une meilleure compréhension de la biologie de soupape en réponse à des stress physiques aiderait élucider les mécanismes de la pathogenèse de la vanne. En retour, cela pourrait aider dans le développement de thérapies non invasives telles que l&#39;intervention pharmaceutique ou de prévention. Bioréacteurs Plusieurs ont déjà été développés pour étudier la mécanobiologie des valves cardiaques natives ou conçu 6-9. Bioréacteurs pulsatile ont également été développées pour étudier une gamme de tissus, y compris le cartilage 10, 11 os et de la vessie 12. Le but de ce travail était de développer un système de pression cyclique qui pourrait être utilisée pour élucider la réponse biologique de tracts de la valve aortique à des charges de pression accrue. Le système se composait d&#39;une chambre d&#39;acrylique dans lequel placer des échantillons et de produire une pression cyclique, vannes à membrane viton électrovannes pour contrôler la synchronisation du cycle de pression, et un ordinateur pour contrôler des appareils électriques. La pression a été contrôlée à l&#39;aide d&#39;un transducteur de pression, et le signal a été conditionné à l&#39;aide d&#39;un conditionneur cellule de charge. Un programme LabVIEW réglementées utilisant la pression d&#39;un périphérique analogique à la pompe à air comprimé dans le système au taux approprié. Le système a imité les niveaux dynamiques de pression transvalvulaire associés à la valve aortique, une vague en dents de scie produit une augmentation progressive de la pression, typique du gradient de pression transvalvulaire qui est présent à travers la vanne pendant la diastole, suivie d&#39;une forte chute de pression représentant ouverture de la vanne de systole. Le programme LabVIEW permet aux utilisateurs de contrôler l&#39;ampleur et la fréquence de la pression cyclique. Le système a été en mesure de soumettre des échantillons de tissus à des conditions de pression physiologique et pathologique. Ce dispositif peut être utilisé pour accroître notre compréhension de la façon dont les valves cardiaques de réagir aux changements dans l&#39;environnement local mécanique.

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

Un bioréacteur pression cyclique capable de soumettre des tissus de valves cardiaques à des conditions de pression physiologique et pathologique a été conçu. Un programme LabVIEW permet aux utilisateurs de contrôler l&#39;ampleur de pression, l&#39;amplitude et la fréquence. Ce dispositif peut être utilisé pour étudier la mécanobiologie des tissus de valves cardiaques ou des cellules isolées.

Conception d&#39;un bioréacteur pour la pression cyclique Ex Vivo Étude des valves cardiaques aortiques

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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15.6K vues.  Mississippi State University. Un bioréacteur pression cyclique capable de soumettre des tissus de valves cardiaques à des conditions de pression physiologique et pathologique a été conçu. Un programme LabVIEW permet aux utilisateurs de contrôler l'ampleur de pression, l'amplitude et la fréquence. Ce dispositif peut être utilisé pour étudier la mécanobiologie des tissus de valves cardiaques ou des cellules isolées.

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

Patient-specific Modeling of the Heart: Estimation of Ventricular Fiber Orientations

Patient-specific simulations of heart (dys)function aimed at personalizing cardiac therapy are hampered by the absence of in vivo imaging technology for clinically acquiring myocardial fiber orientations. The objective of this project was to develop a methodology to estimate cardiac fiber orientations from in vivo images of patient heart geometries. An accurate representation of ventricular geometry and fiber orientations was reconstructed, respectively, from high-resolution ex vivo structural magnetic resonance (MR) and diffusion tensor (DT) MR images of a normal human heart, referred to as the atlas. Ventricular geometry of a patient heart was extracted, via semiautomatic segmentation, from an in vivo computed tomography (CT) image. Using image transformation algorithms, the atlas ventricular geometry was deformed to match that of the patient. Finally, the deformation field was applied to the atlas fiber orientations to obtain an estimate of patient fiber orientations. The accuracy of the fiber estimates was assessed using six normal and three failing canine hearts. The mean absolute difference between inclination angles of acquired and estimated fiber orientations was 15.4 &deg;. Computational simulations of ventricular activation maps and pseudo-ECGs in sinus rhythm and ventricular tachycardia indicated that there are no significant differences between estimated and acquired fiber orientations at a clinically observable level.The new insights obtained from the project will pave the way for the development of patient-specific models of the heart that can aid physicians in personalized diagnosis and decisions regarding electrophysiological interventions.

A methodology to estimate ventricular fiber orientations from in vivo images of patient heart geometries for personalized modeling is described. Validation of the methodology performed using normal and failing canine hearts demonstrate that that there are no significant differences between estimated and acquired fiber orientations at a clinically observable level.

Spécifique au patient Modeling of the Heart: Estimation des orientations des fibres ventriculaires

Patient-specific  simulations of heart (dys)function aimed at personalizing cardiac therapy are hampered  by the absence of in vivo imaging technology for ...

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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.

Conception d&#39;un bioréacteur de chargement mécanique biaxial pour l&#39;ingénierie tissulaire

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

Operation of a Benchtop Bioreactor

Fermentation systems are used to provide an optimal growth environment for many different types of cell cultures. The ability afforded by fermentors to carefully control temperature, pH, and dissolved oxygen concentrations in particular makes them essential to efficient large scale growth and expression of fermentation products. This video will briefly describe the advantages of the fermentor over the shake flask. It will also identify key components of a typical benchtop fermentation system and give basic instruction on setup of the vessel and calibration of its probes. The viewer will be familiarized with the sterilization process and shown how to inoculate the growth medium in the vessel with culture. Basic concepts of operation, sampling, and harvesting will also be demonstrated. Simple data analysis and system cleanup will also be discussed.

Fermentors are used to increase culture yield and productivity of bioengineered cells. After screening multiple microbial or animal cell culture candidates in shake flasks, the next logical step is to increase the selected culture&#x2019;s biomass with the fermentor. This video demonstrates the setup and operation of a typical benchtop bioreactor system.

Fonctionnement d&#39;un bioréacteur de laboratoire

Fermentation systems are used to provide an optimal growth environment for many different types of cell cultures. The ability afforded by fermentors to ...

Characterization of Complex Systems Using the Design of Experiments Approach: Transient Protein Expression in Tobacco as a Case Study

Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the additional advantage of short development and production times, but expression levels can vary significantly between batches thus giving rise to regulatory concerns in the context of good manufacturing practice. We used a design of experiments (DoE) approach to determine the impact of major factors such as regulatory elements in the expression construct, plant growth and development parameters, and the incubation conditions during expression, on the variability of expression between batches. We tested plants expressing a model anti-HIV monoclonal antibody (2G12) and a fluorescent marker protein (DsRed). We discuss the rationale for selecting certain properties of the model and identify its potential limitations. The general approach can easily be transferred to other problems because the principles of the model are broadly applicable: knowledge-based parameter selection, complexity reduction by splitting the initial problem into smaller modules, software-guided setup of optimal experiment combinations and step-wise design augmentation. Therefore, the methodology is not only useful for characterizing protein expression in plants but also for the investigation of other complex systems lacking a mechanistic description. The predictive equations describing the interconnectivity between parameters can be used to establish mechanistic models for other complex systems.

We describe a design of experiments approach that can be used to determine and model the influence of transgene regulatory elements, plant growth and development parameters, and incubation conditions on the transient expression of monoclonal antibodies and reporter proteins in plants.

Caractérisation des systèmes complexes à l&#39;aide de la conception des expériences approche: l&#39;expression transitoire de protéines dans le tabac comme une étude de cas

Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the ...

Anatomically Realistic Neonatal Heart Model for Use in Neonatal Patient Simulators

Neonatal patient simulators (NPS) are artificial patient surrogates used in the context of medical simulation training. Neonatologists and nursing staff practice clinical interventions such as chest compressions to ensure patient survival in the case of bradycardia or cardiac arrest. The simulators used currently are of low physical fidelity and therefore cannot provide qualitative insight into the procedure of chest compressions. The embedding of an anatomically realistic heart model in future simulators enables the detection of cardiac output generated during chest compressions; this can provide clinicians with an output parameter, which can deepen the understanding of the effect of the compressions in relation to the amount of blood flow generated. Before this monitoring can be achieved, an anatomically realistic heart model must be created containing: two atria, two ventricles, four heart valves, pulmonary veins and arteries, and systemic veins and arteries. This protocol describes the procedure for creating such a functional artificial neonatal heart model by utilizing a combination of magnetic resonance imaging (MRI), 3D printing, and casting in the form of cold injection molding. Using this method with flexible 3D printed inner molds in the injection molding process, an anatomically realistic heart model can be obtained.

This protocol describes a procedure for creating functional artificial neonatal heart models by utilizing a combination of magnetic resonance imaging, 3D printing, and injection molding. The purpose of these models is for integration into the next generation of neonatal patient simulators and as a tool for physiological and anatomical studies.

Modèle coeur néonatale anatomiquement réaliste pour une utilisation dans les simulateurs patients néonatales

Neonatal patient simulators (NPS) are artificial patient surrogates used in the context of medical simulation training. Neonatologists and nursing staff ...

Light-sheet Fluorescence Microscopy for the Study of the Murine Heart

Light-sheet fluorescence microscopy has been widely used for rapid image acquisition with a high axial resolution from micrometer to millimeter scale. Traditional light-sheet techniques involve the use of a single illumination beam directed orthogonally at sample tissue. Images of large samples that are produced using a single illumination beam contain stripes or artifacts and suffer from a reduced resolution due to the scattering and absorption of light by the tissue. This study uses a dual-sided illumination beam and a simplified CLARITY optical clearing technique for the murine heart. These techniques allow for deeper imaging by removing lipids from the heart and produce a large field of imaging, greater than 10 x 10 x 10 mm3. As a result, this strategy enables us to quantify the ventricular dimensions, track the cardiac lineage, and localize the spatial distribution of cardiac-specific proteins and ion-channels from the post-natal to adult mouse hearts with sufficient contrast and resolution.

This study uses a dual-sided illumination light-sheet fluorescence microscopy (LSFM) technique combined with optical clearing to study the murine heart.

Microscopie de Fluorescence lumière-feuille pour l’étude du coeur murin

Light-sheet fluorescence microscopy has been widely used for rapid image acquisition with a high axial resolution from micrometer to millimeter scale. ...

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.

Un nouveau modèle Ex Vivo pour l’évaluation des performances matérielles Injection sous-muqueuse endoscopique

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

Biaxial Mechanical Characterizations of Atrioventricular Heart Valves

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive models, which provide a mathematical representation of the mechanical function of those structures. This presented biaxial mechanical testing protocol involves (i) tissue acquisition, (ii) the preparation of tissue specimens, (iii) biaxial mechanical testing, and (iv) postprocessing of the acquired data. First, tissue acquisition requires obtaining porcine or ovine hearts from a local Food and Drug Administration-approved abattoir for later dissection to retrieve the valve leaflets. Second, tissue preparation requires using tissue specimen cutters on the leaflet tissue to extract a clear zone for testing. Third, biaxial mechanical testing of the leaflet specimen requires the use of a commercial biaxial mechanical tester, which consists of force-controlled, displacement-controlled, and stress-relaxation testing protocols to characterize the leaflet tissue&#39;s mechanical properties. Finally, post-processing requires the use of data image correlation techniques and force and displacement readings to summarize the tissue&#39;s mechanical behaviors in response to external loading. In general, results from biaxial testing demonstrate that the leaflet tissues yield a nonlinear, anisotropic mechanical response. The presented biaxial testing procedure is advantageous to other methods since the method presented here allows for a more comprehensive characterization of the valve leaflet tissue under one unified testing scheme, as opposed to separate testing protocols on different tissue specimens. The proposed testing method has its limitations in that shear stress is potentially present in the tissue sample. However, any potential shear is presumed negligible.

This protocol involves characterizations of atrioventricular valve leaflets with force-controlled, displacement-controlled, and stress-relaxation biaxial mechanical testing procedures. Results acquired with this protocol can be used for constitutive model development to simulate the mechanical behavior of functioning valves under a finite element simulation framework.

Biaxiales caractérisations mécaniques des valvules auriculo-ventriculaire

Extensive biaxial mechanical testing of the atrioventricular heart valve leaflets can be utilized to derive&#160;optimal parameters used in constitutive ...

A Friction Testing-Bioreactor Device for Study of Synovial Joint Biomechanics, Mechanobiology, and Physical Regulation

In primary osteoarthritis (OA), normal 'wear and tear' associated with aging inhibits the ability of cartilage to sustain its load-bearing and lubrication functions, fostering a deleterious physical environment. The frictional interactions of articular cartilage and synovium may influence joint homeostasis through tissue level wear and cellular mechanotransduction. To study these mechanical and mechanobiological processes, a device capable of replicating the motion of the joint is described. The friction testing device controls the delivery of reciprocal translating motion and normal load to two contacting biological counterfaces. This study adopts a synovium-on-cartilage configuration, and friction coefficient measurements are presented for tests performed in a phosphate-buffered saline (PBS) or synovial fluid (SF) bath. The testing was performed for a range of contact stresses, highlighting the lubricating properties of SF under high loads. This friction testing device can be used as a biomimetic bioreactor for studying the physical regulation of living joint tissues in response to applied physiologic loading associated with diarthrodial joint articulation.

The present protocol describes a friction testing device that applies simultaneous reciprocal sliding and normal load to two contacting biological counterfaces.

Un dispositif de bioréacteur d’essai de friction pour l’étude de la biomécanique des articulations synoviales, de la mécanobiologie et de la régulation physique

In primary osteoarthritis (OA), normal 'wear and tear' associated with aging inhibits the ability of cartilage to sustain its load-bearing and lubrication ...

Procurement and Decellularization of Rat Hindlimbs Using an Ex Vivo Perfusion-Based Bioreactor for Vascularized Composite Allotransplantation

Patients with severe traumatic injuries and tissue loss require complex surgical reconstruction. Vascularized composite allotransplantation (VCA) is an evolving reconstructive avenue for transferring multiple tissues as a composite subunit. Despite the promising nature of VCA, the long-term immunosuppressive requirements are a significant limitation due to the increased risk of malignancies, end-organ toxicity, and opportunistic infections. Tissue engineering of acellular composite scaffolds is a potential alternative in reducing the need for immunosuppression. Herein, the procurement of a rat hindlimb and its subsequent decellularization using sodium dodecyl sulfate (SDS) is described. The procurement strategy presented is based upon the common femoral artery. A machine perfusion-based bioreactor system was constructed and used for ex vivo decellularization of the hindlimb. Successful perfusion decellularization was performed, resulting in a white translucent-like appearance of the hindlimb. An intact, perfusable, vascular network throughout the hindlimb was observed. Histological analyses showed the removal of nuclear contents and the preservation of tissue architecture across all tissue compartments.

Procurement and Decellularization of Rat Hindlimbs Using an Ex Vivo Perfusion-Based Bioreactor for Vascularized Composite Allotransplantation

We describe the surgical technique and decellularization process for composite rat hindlimbs. Decellularization is conducted using low-concentration sodium dodecyl sulfate through an ex vivo machine perfusion system.

Obtention et décellularisation de membres postérieurs de rat à l’aide d’un bioréacteur ex vivo basé sur la perfusion pour l’allotransplantation composite vascularisée

Patients with severe traumatic injuries and tissue loss require complex surgical reconstruction. Vascularized composite allotransplantation (VCA) is an ...