Nous tenons à remercier Dionna Gamble, Allison Larson, et Katia Torres pour l&#39;aide à la production du modèle et les mesures, Monica Mahre d&#39;assistance manuscrit, Gary Williams pour l&#39;assistance technique, Jerrald Spencer Jr. d&#39;assistance avec les chiffres et les Services d&#39;imagerie Fairview à l&#39; Université du Minnesota. Le financement a été reçu à l&#39;Institut de génie en médecine (Université du Minnesota) et dans le cadre d&#39;un contrat de recherche avec Medtronic Inc.

Procédure Le tableau 1 résume les matériaux utilisés au cours du processus. Figure 1 donne un aperçu du processus. 1. Échantillons et analyse Préparation <ol><li> Procurez-vous les cœurs humains isolés fraîches et ensuite perfusion fixer dans 10% de formol tamponné dans leur état en fin de diastole. </li><li> Rincez les cœurs doivent être analysées dans l&#39;eau le jour avant la numérisation afin d&#39;éliminer la majorité de la formaline. </li><li> Avant d&#39;aller au scanner, cathétériser le sinus (CS) veine coronaire dans chaque cœur avec un cathéter à ballonnet de venogram. Obtenir l&#39;accès au CS soit par la veine cave supérieure ou inférieure sous visualisation directe ou l&#39;utilisation de videoscopes. </li><li> Une fois en place, gonfler le ballon de ce cathéter venogram pour ancrer le cathéter dans le CS. </li><li> Placez chaque cœur dans un conteneur de polymère pouvant être scellé au sommet d&#39;une éponge qui a été conçu de sorte quele cœur peut s&#39;asseoir dans sa position anatomique attitudinally correct. </li></ol> 2. La tomodensitométrie <ol><li> Placez un cœur donné sur la vitre du scanner CT comme si un patient a été couché sur le dos et la tête la première sur le scanner. </li><li> Connecter l&#39;extrémité proximale du cathéter de phlébogramme à un injecteur qui contient deux seringues d&#39;injection: une pour le contraste et l&#39;autre pour une solution saline. </li><li> Injecter automatiquement 40 ml de contraste dans le système veineux cardiaque à 5 ml / sec. </li><li> CT Scan cœur 8 sec après l&#39;injection de contraste est lancée. Réglez le scanner de 512 x 512 pixels de résolution avec 0,6 épaisseur de coupe mm. </li><li> Injecter automatiquement les 40 ml de solution saline dans le système veineux cardiaque à 5 ml / s pour rincer le contraste. </li><li> Exporter les images DICOM CT sur un disque dur externe. </li></ol> 3. Reconstruction et mesures <ol><li> Téléchargez CT images DICOM dans Mimics Software. </li><li> Générer un masque pour le CT images qui ne contient que des pixels avec des unités de haute Hounsfield pour mettre en évidence que le contraste présent dans le cœur. </li><li> Retirer contraste qui a fui dans les chambres ou diffus dans le tissu de sorte que le masque ne contient que le contraste dans les grandes veines cardiaques. </li><li> Remplir manuellement dans des poches d&#39;air au sein d&#39;une trame de la veine proposée par trame. </li><li> Générer un objet 3D à partir du masque résultant. </li><li> Lisser et terminer cet objet pour éliminer les géométries difficiles. Vidéo 1 présente un de ces modèles 3D tournant dans l&#39;espace. </li><li> Générer médianes pour chaque modèle 3D créé. </li><li> L&#39;utilisation de ces axes, mesurer la longueur de l&#39;arc, l&#39;angle de branchement, tortuosité (longueur de l&#39;arc / distance linéaire) et diamètres pour chaque navire majeur dans chaque cœur. Notre nomenclature anatomique utilisé est affiché dans la figure 2. </li></ol>

<ol>
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J., Achenbach, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+evaluation+of+cardiac+veins+with+16-MDCT+angiography.">Noninvasive evaluation of cardiac veins with 16-MDCT angiography.</a> AJR. Am. J. Roentgenol. 185, 1001-1006 (2005).</li><li>Gerber, T. C., Sheedy, P. F., Bell, M. R., Hayes, D. L., Rumberger, J. A., Behrenbeck, T., Holmes, D. R., Schwartz, R. S. <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+coronary+venous+system+using+electron+beam+computed+tomography.">Evaluation of the coronary venous system using electron beam computed tomography.</a> Int. J. Cardiovasc. Imaging. 17, 65-75 (2001).</li><li>Jongbloed, M. R. M., Lamb, H. J., Bax, J. J., Schuijf, J. D., de Roos, A., vander Wall, E. E., Schalij, M. 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Anat. 22, 35-39 (2000).</li><li>Tada, H., Kurosaki, K., Naito, S., Koyama, K., Itoi, K., Ito, S., Ueda, M., Shinbo, G., Hoshizaki, H., Nogami, A., Oshima, S., Taniguchi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+visualization+of+the+coronary+venous+system+using+multidetector+row+computed+tomography.">Three-dimensional visualization of the coronary venous system using multidetector row computed tomography.</a> Circ. J. 69, 165-170 (2005).</li><li>Van de Veire, N. R., Schuijf, J. D., Sutter, J. D., Devos, D., Bleeker, G. B., de Roos, A., vander Wall, E. E., Schalij, M. J., Bax, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-invasive+visualization+of+the+cardiac+venous+system+in+coronary+artery+disease+patients+using+64-slice+computed+tomography.">Non-invasive visualization of the cardiac venous system in coronary artery disease patients using 64-slice computed tomography.</a> J. Am. Coll. Cardiol. 48, 1832-1838 (2006).</li><li>de Jong, P. A., Mayo, J. R., Golmohammadi, K., Nakano, Y., Lequin, M. H., Tiddens, H. A., Aldrich, J., Coxson, H. O., Sin, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Estimation+of+cancer+mortality+associated+with+repetitive+computed+tomography+scanning.">Estimation of cancer mortality associated with repetitive computed tomography scanning.</a> Am. J. Respir. Crit. Care Med. 173, 199-203 (2006).</li><li>Martin, D. R., Semelka, R. C., Chapman, A., Peters, H., Finn, P. J., Kalb, B., Thomsen, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nephrogenic+systemic+fibrosis+versus+contrast-induced+nephropathy:+risks+and+benefits+of+contrast-enhanced+MR+and+CT+in+renally+impaired+patients.">Nephrogenic systemic fibrosis versus contrast-induced nephropathy: risks and benefits of contrast-enhanced MR and CT in renally impaired patients.</a> J. Magn. Reson. Imaging. 30, 1350-1356 (2009).</li></ol>

Aucun conflit d&#39;intérêt déclaré.

Notre laboratoire développe une bibliothèque d&#39;échantillons cardiaques fixes perfusion pour diverses études anatomiques. À ce jour, nous avons plus de 240 spécimens conservés. Les méthodes spécifiques que nous avons utilisés pour préparer ces spécimens ont été décrits précédemment 3. La présente étude décrit une nouvelle méthodologie pour la cartographie du système veineux cardiaque humaine et pour le développement d&#39;une base de données anatomiques, qui pourrait être utilisé ...

anatomical reconstructions of the human cardiac venous system using contrast-computed tomography of perfusion-fixed specimens

Une compréhension détaillée de la complexité et de la variabilité relative dans le système veineux cardiaque humain est crucial pour le développement de dispositifs cardiaques qui nécessitent un accès à ces navires. Par exemple, l&#39;anatomie veineuse cardiaque est connu pour être l&#39;une des principales limites de la bonne livraison de la thérapie de resynchronisation cardiaque (CRT) 1 Par conséquent, le développement d&#39;une base de données de paramètres anatomiques pour les systèmes veineux cardiaques humaines peut aider à la conception de livraison CRT des dispositifs pour surmonter une telle limitation. Dans ce projet de recherche, les paramètres anatomiques ont été obtenus à partir de reconstructions 3D du système veineux à l&#39;aide de contraste tomodensitométrie (TDM) et un logiciel de modélisation (Materialise, Louvain, Belgique). Les paramètres suivants ont été évalués pour chaque veine: longueur d&#39;arc, tortuosité, angle de branchement, la distance à l&#39;orifice du sinus coronaire, et le diamètre du vaisseau. CRT est un traitement potentiel pour les patients avec asynchronisme électromécanique. Environ 10-20% des patients atteints d&#39;insuffisance cardiaque peuvent bénéficier de CRT 2. Asynchronisme électromécanique implique que les parties de l&#39;activer myocarde et le contrat plus tôt ou plus tard que la voie de conduction normale du cœur. Dans CRT, dyssynchrone zones du myocarde sont traités par stimulation électrique. CRT stimulation implique généralement sondes de stimulation qui stimulent l&#39;oreillette droite (RA), le ventricule droit (VD) et du ventricule gauche (VG) pour produire des rythmes plus resynchronisés. La sonde VG est généralement implanté à l&#39;intérieur d&#39;une veine cardiaque, dans le but de le superposer à l&#39;intérieur de l&#39;emplacement de la dernière activation du myocarde. Nous pensons que les modèles obtenus et les analyses de ceux-ci favoriseront l&#39;enseignement de l&#39;anatomie des patients, des étudiants, des cliniciens, et les concepteurs de dispositifs médicaux. Les méthodes employées ici peuvent également être utilisées pour étudier d&#39;autres caractéristiques anatomiques de nos spécimens cardiaques humaines, telles queles artères coronaires. Afin d&#39;encourager davantage la valeur éducative de cette recherche, nous avons partagé les modèles veineux sur notre site internet en accès libre: <a href="http://www.vhlab.umn.edu/atlas" target="_blank">www.vhlab.umn.edu / atlas</a> .

Le tableau 2 présente les paramètres anatomiques médiane des grandes veines cardiaques pour 42 spécimens de cœur humain. Tous les échantillons contenaient de coeur une veine interventriculaire postérieure (PIV) et la veine interventriculaire antérieure (AIV). Certains échantillons contenaient plus d&#39;une veine postérieure de l&#39;(PVLV), la veine LV postéro-latéral (VPL), veine latérale de gauche (LLV), et / ou de la veine antéro-latérale (ALV), tandis que d&#39;autres cœurs peuvent ...

Watch this Scientific Journal Video about Anatomical Reconstructions of the Human Cardiac Venous System using Contrast-computed Tomography of Perfusion-fixed Specimens at JoVE.com

Anatomical Reconstructions of the Human Cardiac Venous System using Contrast-computed Tomography of Perfusion-fixed Specimens

L&#39;objectif de cette recherche est de recréer, puis accéder à l&#39;anatomie du système veineux cardiaque humaine en utilisant des reconstitutions en 3D générés par contraste tomodensitométrie.

Reconstructions anatomiques du système veineux cardiaque humaine à l&#39;aide de contraste tomodensitométrie des échantillons Perfusion-fixes

A detailed  understanding of the complexity and relative variability within the human  cardiac venous system is crucial for the development of cardiac ...

anatomical-reconstructions-human-cardiac-venous-system-using-contrast

Research

JoVE Journal

Bioengineering

11.7K vues.  University of Minnesota. L'objectif de cette recherche est de recréer, puis accéder à l'anatomie du système veineux cardiaque humaine en utilisant des reconstitutions en 3D générés par contraste tomodensitométrie.

Vidéo: Anatomical Reconstructions of the Human Cardiac Venous System using Contrast-computed Tomography of Perfusion-fixed Specimens

Bacterial Detection &amp; Identification Using Electrochemical Sensors

Electrochemical sensors are widely used for rapid and accurate measurement of blood glucose and can be adapted for detection of a wide variety of analytes. Electrochemical sensors operate by transducing a biological recognition event into a useful electrical signal. Signal transduction occurs by coupling the activity of a redox enzyme to an amperometric electrode. Sensor specificity is either an inherent characteristic of the enzyme, glucose oxidase in the case of a glucose sensor, or a product of linkage between the enzyme and an antibody or probe.
Here, we describe an electrochemical sensor assay method to directly detect and identify bacteria. In every case, the probes described here are DNA oligonucleotides. This method is based on sandwich hybridization of capture and detector probes with target ribosomal RNA (rRNA). The capture probe is anchored to the sensor surface, while the detector probe is linked to horseradish peroxidase (HRP). When a substrate such as 3,3',5,5'-tetramethylbenzidine (TMB) is added to an electrode with capture-target-detector complexes bound to its surface, the substrate is oxidized by HRP and reduced by the working electrode. This redox cycle results in shuttling of electrons by the substrate from the electrode to HRP, producing current flow in the electrode.

We describe an electrochemical sensor assay method for rapid bacterial detection and identification. The assay involves a sensor array functionalized with DNA oligonucleotide capture probes for ribosomal RNA (rRNA) species-specific sequences. Sandwich hybridization of target rRNA with the capture probe and a horseradish peroxidase-linked DNA oligonucleotide detector probe produces a measurable amperometric current.

Bacterial Detection &amp; identification au moyen de capteurs électrochimiques

Electrochemical  sensors are widely used for rapid and accurate measurement of blood glucose and  can be adapted for detection of a wide variety of ...

Recherche

Bio-ingénierie

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.

La culture de la souris cardiaque Vannes dans le système de culture de tissus 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 ...

Studying Protein Function and the Role of Altered Protein Expression by Antibody Interference and Three-dimensional Reconstructions

A strict management of protein expression is not only essential to every organism alive, but also an important strategy to investigate protein functions in cellular models. Therefore, recent research invented different tools to target protein expression in mammalian cell lines or even animal models, including RNA and antibody interference. While the first strategy has gathered much attention during the past two decades, peptides &#160;mediating a translocation of antibody cargos across cellular membranes and into cells, obtained much less interest. In this publication, we provide a detailed protocol how to utilize a peptide carrier named Chariot in human embryonic kidney cells as well as in primary hippocampal neurons to perform antibody interference experiments and further illustrate the application of three-dimensional reconstructions in analyzing protein function. Our findings suggest that Chariot is, probably due to its nuclear localization signal, particularly well-suited to target proteins residing in the soma and the nucleus. Remarkably, when applying Chariot to primary hippocampal cultures, the reagent turned out to be surprisingly well accepted by dissociated neurons.

Controlling protein expression is not only essential to every organism alive, but also an important strategy to investigate protein functions in cellular models. The protocol presented shows the application of antibody interference in mammalian cells including primary hippocampal neurons and demonstrates the use of three-dimensional reconstructions in studying protein function.

Etudier la fonction des protéines et le rôle de Altered Expression des protéines par les interférences des anticorps et des reconstructions tridimensionnelles

A strict management of protein expression is not only essential to every organism alive, but also an important strategy to investigate protein functions ...

Construction of Defined Human Engineered Cardiac Tissues to Study Mechanisms of Cardiac Cell Therapy

Human cardiac tissue engineering can fundamentally impact therapeutic discovery through the development of new species-specific screening systems that replicate the biofidelity of three-dimensional native human myocardium, while also enabling a controlled level of biological complexity, and allowing non-destructive longitudinal monitoring of tissue contractile function. Initially, human engineered cardiac tissues (hECT) were created using the entire cell population obtained from directed differentiation of human pluripotent stem cells, which typically yielded less than 50% cardiomyocytes. However, to create reliable predictive models of human myocardium, and to elucidate mechanisms of heterocellular interaction, it is essential to accurately control the biological composition in engineered tissues. 
To address this limitation, we utilize live cell sorting for the cardiac surface marker SIRP&#945; and the fibroblast marker CD90 to create tissues containing a 3:1 ratio of these cell types, respectively, that are then mixed together and added to a collagen-based matrix solution. Resulting hECTs are, thus, completely defined in both their cellular and extracellular matrix composition.
Here we describe the construction of defined hECTs as a model system to understand mechanisms of cell-cell interactions in cell therapies, using an example of human bone marrow-derived mesenchymal stem cells (hMSC) that are currently being used in human clinical trials. The defined tissue composition is imperative to understand how the hMSCs may be interacting with the endogenous cardiac cell types to enhance tissue function. A bioreactor system is also described that simultaneously cultures six hECTs in parallel, permitting more efficient use of the cells after sorting.

This manuscript describes the creation of defined engineered cardiac tissues using surface marker expression and cell sorting. The defined tissues can then be used in a multi-tissue bioreactor to investigate mechanisms of cardiac cell therapy in order to provide a functional, yet controlled, model system of the human heart.

Construction des Défini humaines Engineered cardiaques Tissues pour étudier les mécanismes de la thérapie cellulaire cardiaque

Human cardiac tissue engineering can fundamentally impact therapeutic discovery through the development of new species-specific screening systems that ...

In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography

The use of Micro-Computed Tomography (MicroCT) for in vivo studies of small animals as models of human disease has risen tremendously due to the fact that MicroCT provides quantitative high-resolution three-dimensional (3D) anatomical data non-destructively and longitudinally. Most importantly, with the development of a novel preclinical iodinated contrast agent called eXIA160, functional and metabolic assessment of the heart became possible. However, prior to the advent of commercial MicroCT scanners equipped with X-ray flat-panel detector technology and easy-to-use cardio-respiratory gating, preclinical studies of cardiovascular disease (CVD) in small animals required a MicroCT technologist with advanced skills, and thus were impractical for widespread implementation. The goal of this work is to provide a practical guide to the use of the high-speed Quantum FX MicroCT system for comprehensive determination of myocardial global and regional function along with assessment of myocardial perfusion, metabolism and viability in healthy mice and in a cardiac ischemia mouse model induced by permanent occlusion of the left anterior descending coronary artery (LAD).

In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography

This method outlines the use of Quantum Micro-Computed Tomography (MicroCT) to assess cardiac morphology, function, perfusion, metabolism and viability with iodinated contrast agent in mice with experimentally-induced myocardial ischemia. The technique can be applied for non-destructive high-throughput longitudinal in vivo imaging of various animal models of human heart disease.

In Vivo évaluation quantitative de la structure du myocarde, Fonction, perfusion et la viabilité utilisant la tomographie cardiaque Micro-calculées

The use of Micro-Computed Tomography (MicroCT) for in vivo studies of small animals as models of human disease has risen tremendously due to the fact that ...

Using Extraordinary Optical Transmission to Quantify Cardiac Biomarkers in Human Serum

For a biosensing platform to have clinical relevance in point-of-care (POC) settings, assay sensitivity, reproducibility, and ability to reliably monitor analytes against the background of human serum are crucial.
Nanoimprinting lithography (NIL) was used to fabricate, at a low cost, sensing areas as large as 1.5 mm x 1.5 mm. The sensing surface was made of high-fidelity arrays of nanoholes, each with an area of about 140 nm2. The great reproducibility of NIL made it possible to employ a one-chip, one-measurement strategy on 12 individually manufactured surfaces, with minimal chip-to-chip variation. These nanoimprinted localized surface plasmon resonance (LSPR) chips were extensively tested on their ability to reliably measure a bioanalyte at concentrations varying from 2.5 to 75 ng/mL amidst the background of a complex biofluid-in this case, human serum. The high fidelity of NIL enables the generation of large sensing areas, which in turn eliminates the need for a microscope, as this biosensor can be easily interfaced with a commonly available laboratory light source. These biosensors can detect cardiac troponin in serum with a high sensitivity, at a limit of detection (LOD) of 0.55 ng/mL, which is clinically relevant. They also show low chip-to-chip variance (due to the high quality of the fabrication process). The results are commensurable with widely used enzyme-linked immunosorbent assay (ELISA)-based assays, but the technique retains the advantages of an LSPR-based sensing platform (i.e., amenability to miniaturization and multiplexing, making it more feasible for POC applications).

This work describes a nanoimprinting lithography method to fabricate high-quality sensing arrays that work on the principle of extraordinary optical transmission. The biosensor is low-cost, robust, easy to use, and can detect cardiac troponin I in serum at clinically relevant concentrations (99th percentile cutoff &#8764;10-400 pg/mL, depending on the assay).

À l’aide de Transmission optique extraordinaire pour quantifier les biomarqueurs cardiaques dans le sérum humain

For a biosensing platform to have clinical relevance in point-of-care (POC) settings, assay sensitivity, reproducibility, and ability to reliably monitor ...

Efficient Generation and Editing of Feeder-free IPSCs from Human Pancreatic Cells Using the CRISPR-Cas9 System

Embryonic and induced pluripotent stem cells can self-renew and differentiate into multiple cell types of the body. The pluripotent cells are thus coveted for research in regenerative medicine and are currently in clinical trials for eye diseases, diabetes, heart diseases, and other disorders. The potential to differentiate into specialized cell types coupled with the recent advances in genome editing technologies including the CRISPR/Cas system have provided additional opportunities for tailoring the genome of iPSC for varied applications including disease modeling, gene therapy, and biasing pathways of differentiation, to name a few. Among the available editing technologies, the CRISPR/Cas9 from Streptococcus pyogenes has emerged as a tool of choice for site-specific editing of the eukaryotic genome. The CRISPRs are easily accessible, inexpensive, and highly efficient in engineering targeted edits. The system requires a Cas9 nuclease and a guide sequence (20-mer) specific to the genomic target abutting a 3-nucleotide &#34;NGG&#34; protospacer-adjacent-motif (PAM) for targeting Cas9 to the desired genomic locus, alongside a universal Cas9 binding tracer RNA (together called single guide RNA or sgRNA). Here we present a step-by-step protocol for efficient generation of feeder-independent and footprint-free iPSC and describe methodologies for genome editing of iPSC using the Cas9 ribonucleoprotein (RNP) complexes. The genome editing protocol is effective and can be easily multiplexed by pre-complexing sgRNAs for more than one target with the Cas9 protein and simultaneously delivering into the cells. Finally, we describe a simplified approach for identification and characterization of iPSCs with desired edits. Taken together, the outlined strategies are expected to streamline generation and editing of iPSC for manifold applications.

This protocol describes in detail the generation of footprint-free induced pluripotent stem cells (iPSCs) from human pancreatic cells in feeder-free conditions, followed by editing using CRISPR/Cas9 ribonucleoproteins and characterization of the modified single-cell clones.

Génération efficace et l’édition de CISP exempte d’engraissement de cellules pancréatiques humaines en utilisant le système CRISPR-Cas9

Embryonic and induced pluripotent stem cells can self-renew and differentiate into multiple cell types of the body. The pluripotent cells are thus coveted ...

A Net Mold-based Method of Scaffold-free Three-Dimensional Cardiac Tissue Creation

This protocol describes a novel and easy net mold-based method to create three-dimensional (3-D) cardiac tissues without additional scaffold material. Human-induced pluripotent stem-cell-derived cardiomyocytes (iPSC-CMs), human cardiac fibroblasts (HCFs), and human umbilical vein endothelial cells (HUVECs) are isolated and used to generate a cell suspension with 70% iPSC-CMs, 15% HCFs, and 15% HUVECs. They are co-cultured in an ultra-low attachment "hanging drop" system, which contains micropores for condensing hundreds of spheroids at one time. The cells aggregate and spontaneously form beating spheroids after 3 days of co-culture. The spheroids are harvested, seeded into a novel mold cavity, and cultured on a shaker in the incubator. The spheroids become a mature functional tissue approximately 7 days after seeding. The resultant multilayered tissues consist of fused spheroids with satisfactory structural integrity and synchronous beating behavior. This new method has promising potential as a reproducible and cost-effective method to create engineered tissues for the treatment of heart failure in the future.

This protocol describes a net mold-based method to create three-dimensional scaffold-free cardiac tissues with satisfactory structural integrity and synchronous beating behavior.

Une méthode axée sur le moule Net de la création de tissu cardiaque exempte d’échafaudage tridimensionnel

This protocol describes a novel and easy net mold-based method to create three-dimensional (3-D) cardiac tissues without additional scaffold material. ...

Rigid Embedding of Fixed and Stained, Whole, Millimeter-Scale Specimens for Section-free 3D Histology by Micro-Computed Tomography

For over a hundred years, the histological study of tissues has been the gold standard for medical diagnosis because histology allows all cell types in every tissue to be identified and characterized. Our laboratory is actively working to make technological advances in X-ray micro-computed tomography (micro-CT) that will bring the diagnostic power of histology to the study of full tissue volumes at cellular resolution (i.e., an X-ray Histo-tomography modality). Toward this end, we have made targeted improvements to the sample preparation pipeline. One key optimization, and the focus of the present work, is a straightforward method for rigid embedding of fixed and stained millimeter-scale samples. Many of the published methods for sample immobilization and correlative micro-CT imaging rely on placing the samples in paraffin wax, agarose, or liquids such as alcohol. Our approach extends this work with custom procedures and the design of a 3-dimensional printable apparatus to embed the samples in an acrylic resin directly into polyimide tubing, which is relatively transparent to X-rays. Herein, sample preparation procedures are described for the samples from 0.5 to 10 mm in diameter, which would be suitable for whole zebrafish larvae and juveniles, or other animals and tissue samples of similar dimensions. As proof of concept, we have embedded the specimens from Danio, Drosophila, Daphnia, and a mouse embryo; representative images from 3-dimensional scans for three of these samples are shown. Importantly, our methodology leads to multiple benefits including rigid immobilization, long-term preservation of laboriously-created resources, and the ability to re-interrogate samples.

We developed protocols and designed a custom apparatus to enable embedding of millimeter-scale specimens. We present sample preparation procedures with an emphasis on embedding in acrylic resin and polyimide tubing to achieve rigid immobilization and long-term storage of specimens for the interrogation of tissue architecture and cell morphology by micro-CT.

Rigide incrustation du fixe et tachée, ensemble, échelle millimétrique spécimens pour histologie exempt de Section 3D de Micro-Computed Tomography

For over a hundred years, the histological study of tissues has been the gold standard for medical diagnosis because histology allows all cell types in ...

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

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

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

Cathéter de lumière à tir latéral intra-cardiaque pour la surveillance du métabolisme cellulaire à l'aide de la spectroscopie d'absorption transmurale des cœurs de mammifères perfusés

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