This study is supported by the Dutch Heart Foundation and the Netherlands Institute for Regenerative Medicine.

Dieses Protokoll folgt den LUMC Richtlinien des Tierforschungsethikkommission. 1. Herstellung des Instruments, Kulturmedium und MTCS Hinweis: Führen Sie alle Vorbereitungen in der Sterilbank. Das MTCS Perfusionskammer, Blasenfalle und Ständer sind in Lieber et al., 2010, 11 beschrieben. <ol><li> Desinfizieren Sie die Zange und Mikro-Schere mit 70% Ethanol. Eine 5 ml-Spritze mit 21G-Nadel mit sterilem Tyrode-Puffer (130 mM NaCl, 5,4 mM KCl, 6,0 mM Hepes, 1,2 mM MgSO 4, 1,2 mM KH 2 PO 4, 20 mM Glucose, 1,5 mM CaCl 2 · 2H 2 O, pH = 7,2). Bereiten Sie eine 5-ml-Spritze mit Nadel 21G mit sterilem KCl-Lösung (100 mM). </li><li> Vorbereitung 65 ml Medium pro Herz: DMEM mit 10% fötalem Kälberserum, Antibiotikum / Antimykotikum ergänzt (A / A; 100 Einheiten Penicillin, 100 ug Streptomycin und 0,25 &amp; mgr; g Amphotericin B / ml), Insulin-Transferrin-Selen (ITS; 10 ug / ml Insulin, 5,5 ug / ml Transferrin, 6,7 ng / ml Natriumselenit) und Filter zu sterilisieren. </li><li> Sterilisieren Sie die Perfusionskammer und Blasenfalle durch Besprühen mit 70% Ethanol und trocken mit einem Papiertuch. Montieren Sie den MTCS (1D), jedoch zunächst ohne die Perfusionskammer. Positionieren Sie den Blasenfalle auf den Ständer. Verwenden Sie eine peristaltische Rollenpumpe mit Easy-Load-Pumpenköpfe. <ol><li> Mit Silikonschlauch Verbindungen zwischen dem Reservoir (50 ml Röhrchen) und der Pumpe, die Pumpe und der Blasenfalle, die Blasenfalle und Reservoir (siehe Figur 1D). Stellen den Schlauch im Inkubator lang genug, um mittlere bis Gasgleichgewicht mit dem Gas in dem Inkubator über die gasdurchlässige Silikonschlauch (1 m) und die Rohrleitung außerhalb des Inkubators so kurz wie möglich zu erreichen. </li></ol></li><li> Füllen Sie die 50-ml-Röhrchen mit 70% Ethanol, schalten Sie die Pumpe (Fließgeschwindigkeit ca. 1 ml / min, um die ordnungsgemäße Zirkulation zu ermöglichen), und lassen Sie das Ethanol circulate für 30 Minuten, um alle Schläuche zu sterilisieren. Das Ethanol durch Entleeren des Behälters und das Abpumpen des Ethanols aus dem System. </li><li> Füllen Sie die 50-ml-Röhrchen mit sterilem destilliertem Wasser, schalten Sie die Pumpe und lassen Sie das Wasser zirkulieren für 30 Minuten, um der restlichen Ethanol loszuwerden. Entfernen Sie das Wasser durch das Leeren des Reservoirs und das Abpumpen des Wassers aus dem System. </li><li> Füllen Sie die 50-ml-Röhrchen mit 45 ml Medium, setzen Sie den Stand im Inkubator. Schalten Sie die Pumpe (Fließgeschwindigkeit ca. 1 ml / min) und leitet das Medium, um alle Schläuche zu füllen, entfernen Sie alle Luftblasen und damit das Medium, um die Gaszusammensetzung in den Inkubator für mindestens 1 Stunde anzupassen. Pflegen Sie den Brutschrank bei Standardgewebekulturbedingungen (5% CO 2 und 37 ° C). Darauf achten, dass keine Luftblasen in den Schläuchen vorhanden sind. </li></ol> 2. Isolierung von Maus Herz <ol><li> Spritzen Sie die Maus mit 500 Einheiten Heparin. Dadurch wird die Verhinderung der Blutgerinnung und ermöglicht das Entfernen von blood aus dem Herzen. Nach 10 min, betäuben die Maus in einer Induktionskammer, die mit 4% Isofluran unter Verwendung eines Präzisions Verdampfer. Die Anästhesie ist ausreichend, wenn sich die Maus nicht mehr reagiert toe Prise. </li><li> Übertragen Sie die Maus auf eine Dissektion Bord und Aufrechterhaltung einer Narkose mittels einer Gesichtsmaske mit einem koaxialen Schaltung verbunden. Desinfizieren Sie das Fell der Maus mit 70% Alkohol. Mit einer Schere öffnen Sie die Bauchhöhle der Hohlvene und Zwerchfell zu entlarven. </li><li> Um das Herz aussetzen, stellen seitliche Einschnitte ausgehend vom letzten zu den ersten Rippen und spiegeln den Brustkorb über Kopf Maus. Stoppen Sie die Anästhesie der Maus wird nicht mehr atmen. Beobachten Sie das Herz schlagen. </li><li> Einfügen der 21G Nadel in eine 5 ml Spritze mit steriler Tyrode-Puffer in die Vena cava inferior von der Bauch in die Brusthöhle (durch die Membran) befestigt ist. Stellen Sie sicher, dass Blut aus der Vena Cava caudal von der Nadeleinführung austreten kann. Perfundieren the Tyrode-Puffer schonend und mit konstantem Druck in die Hohlvene hinein, bis das Herz verliert teilweise seine rote Farbe. Hinweis: Das Herz bleibt Pfosten ermöglicht das Entfernen von Blut aus dem Herzen. </li><li> Ersetzen Sie die Nadel mit der 21G Nadel in eine 5-ml-Spritze mit steriler KCl-Lösung angebracht. Perfundieren vorsichtig die KCl-Lösung in die Hohlvene bis das Herz aufhört zu schlagen, und entfernen Sie die Nadel. Anmerkung: Die KCl-Lösung bewahrt die Herzen in der entspannten diastolischen Phase, die ein leichteres Einsetzen der Perfusion Nadeln und Perfusion der Herzkranzsystem ermöglicht. </li><li> Heben Sie das Herz mit einer gebogenen Pinzette und mit einer Schere zu sezieren das Herz frei von umgebenden Gewebe aber lassen Arterien und Venen proximal des Herzens intakt und mit dem Herzen verbunden. Übertragen Sie die Herzen in ein 15 ml Röhrchen mit eiskaltem PBS, ergänzt mit Antibiotikum / Antimykotikum (A / A). Lagern Sie das Herz in eiskaltem PBS für bis zu 3 Stunden. </li></ol> 3. Cannulation der Maus Hearts in der Perfusionskammer <ol><li> Führen Sie alle in Sterilbank. Übertragen Sie die isolierten Herzen aus dem 15-ml-Röhrchen mit einer 10 cm Petrischale und fügen PBS, ergänzt mit A / A. </li><li> Unter einem Binokular, verwenden Sie die Mikro-Schere und Pinzette, um alle nicht-Herzgewebe zu entfernen, aber die Erhaltung der aufsteigenden Aorta, um zumindest die Bifurkation mit dem Truncus brachiocephalicus und die Lungenvenen, 2 mm proximal des Herzens. Entzieht der Spitze der Spitze des Herzens, um den Zugang zu den linksventrikulären Lumen (typischerweise 2 mm) zu schaffen. Legen Sie die Perfusionskammer in der Flow-Haube unter dem Binokular. </li><li> Bringen Sie ein 5-ml-Spritze mit mittleren bis Einsatzes Nadel mit dem Silikonschlauch. Füllen Sie die Perfusionskammer mit 20 ml Medium, und legte das Herz auf dem Rotationstisch zwischen den 2 abgestumpft Nadeln in der Perfusionskammer (Abbildung 1). Einstellen der Höhe des Rotationsstufe so das Herz vor der positioniertNadeln. </li></ol> 4. Ligation für die Kultivierung der Mitralklappe (siehe Abbildung 1) <ol><li> Ligation der Aorta mit Naht (Seide 7.0). Ligation der linken Herzohr mit Naht. Führen Sie die Nadel (Nr. 1 in Abbildung 1) durch die Lungenvenen in den linken Vorhof und Ligation mit Naht proximal zu seinem Eintritt in den linken Vorhof. Sicherzustellen, dass die Nadel nicht zu weit in den linken Vorhof, da dies die Mitralklappe beschädigen. </li><li> Führen Sie die Nadel (Nr.2 in Abbildung 1) mit linearer Bewegung in den linken Ventrikel. Übertragung des Mediums aus der Perfusionskammer in ein 50 ml Röhrchen. Verschließen Sie die Nadel auf den Herzmuskel mit biokompatiblen Klebstoff. </li><li> Nachdem der Leim getrocknet ist, sorgfältig zu injizieren Medium in das Herz durch den Anschluss eines Mediums Spritze zur Nadel nr.1 und prüfen Sie, ob es eine Leckage. Sicherzustellen, dass die Medium tritt aus Nadel nr.2 und die letzte verbleibende Blut aus dem Herzen durchblutet. </li></ol> 5. Ligation zur Kultivierung der Aortenklappe (siehe 1) <ol><li> Führen Sie die Nadel (nr.1 in Abbildung 1) in der Aorta und Ligation mit Naht. Sicherzustellen, dass die Nadel nicht zu weit in die Aorta, wie dies die Aortenklappe beschädigen. Führen Sie die Nadel (Nr.2 in Abbildung 1) mit linearer Bewegung in den linken Ventrikel. Übertragung des Mediums aus der Perfusionskammer in ein 50 ml Röhrchen. Verschließen Sie die Nadel auf den Herzmuskel mit biokompatiblen Klebstoff. </li><li> Nachdem der Leim getrocknet ist, sorgfältig zu injizieren Medium in das Herz durch den Anschluss eines Mediums Spritze zur Nadel nr.2 und prüfen Sie, ob es eine Leckage. Sicherzustellen, dass die Medium tritt aus Nadel nr.1 und die letzte verbleibende Blut aus dem Herzen durchblutet. </li></ol> 6. Legen Perfusionskammer auf Stand <ol><li> Füllen Sie Perfusionskammer mit den 20 ml-Medium. Zeigen Dichtung und Deckel auf die Kammer und ziehen mit Unterlegscheibe und Schrauben. </li><li> Entfernen Sie die zusammengebauten MTCS vom Incubator. Befestigen Sie die Perfusionskammer auf den Ständer. Den Schlauch (siehe Abbildung 1D). Setzen Sie den Stand im Inkubator (5% CO 2 und 37 ° C). Schließen Sie den Schlauch an der Pumpe. Schalten Sie die Pumpe mit Strömungsgeschwindigkeit um 600 &amp; mgr; l / min. </li><li> Sicherstellen, dass in dem Behälter und / oder die Blasenfalle der Pegel des Mediums ermöglicht die Visualisierungen für das Vorhandensein der Strömung durch das Fallen der eingehenden Mediumstropfen. Nach der Kultivierung wird das Herz aus dem System entfernt, fixiert und für die histologische Untersuchung verarbeitet. </li></ol>

<ol>
	<li>Go, A. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+Disease+and+Stroke+Statistics--2014+Update:+A+Report+From+the+American+Heart+Association.">Heart Disease and Stroke Statistics--2014 Update: A Report From the American Heart Association.</a> Circulation. 129, e28-e292 (2013).</li><li>Gould, S. T., Srigunapalan, S., Simmons, C. A., Anseth, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemodynamic+and+Cellular+Response+Feedback+in+Calcific+Aortic+Valve+Disease.">Hemodynamic and Cellular Response Feedback in Calcific Aortic Valve Disease.</a> Circulation Research. 113 (2), 186-197 (2013).</li><li>Kruithof, B. P. T., Krawitz, S. A., Gaussin, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atrioventricular+valve+development+during+late+embryonic+and+postnatal+stages+involves+condensation+and+extracellular+matrix+remodeling.">Atrioventricular valve development during late embryonic and postnatal stages involves condensation and extracellular matrix remodeling.</a> Developmental biology. 302 (1), 208-217 (2007).</li><li>Schoen, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+valves+and+valvular+pathology:+update+on+function,+disease,+repair,+and+replacement.">Cardiac valves and valvular pathology: update on function, disease, repair, and replacement.</a> Cardiovascular pathology: the official journal of the Society for Cardiovascular Pathology. 14 (4), 189-194 (2005).</li><li>Balachandran, K., Sucosky, P., 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=Hemodynamics+and+mechanobiology+of+aortic+valve+inflammation+and+calcification.">Hemodynamics and mechanobiology of aortic valve inflammation and calcification.</a> International journal of inflammation. , 263870 (2011).</li><li>Butcher, J. T., Simmons, C. A., Warnock, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanobiology+of+the+Aortic+Heart+Valve.">Mechanobiology of the Aortic Heart Valve.</a> The Journal of heart valve disease. 17 (1), 62-73 (2008).</li><li>Balachandran, K., Konduri, S., Sucosky, P., 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=An+ex+vivo+study+of+the+biological+properties+of+porcine+aortic+valves+in+response+to+circumferential+cyclic+stretch.">An ex vivo study of the biological properties of porcine aortic valves in response to circumferential cyclic stretch.</a> Annals of biomedical engineering. 34 (11), 1655-1665 (2006).</li><li>Weiler, M., Hwai Yap, C., Balachandran, K., Padala, M., 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=Regional+analysis+of+dynamic+deformation+characteristics+of+native+aortic+valve+leaflets.">Regional analysis of dynamic deformation characteristics of native aortic valve leaflets.</a> Journal of Biomechanics. 44, 1459-1465 (2011).</li><li>Combs, M. D., Yutzey, K. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heart+valve+development:+Regulatory+networks+in+development+and+disease.">Heart valve development: Regulatory networks in development and disease.</a> Circulation Research. 105, 408-421 (2009).</li><li>Kruithof, B. P. T., Duim, S. N., Moerkamp, A. T., Goumans, M. -. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TGF&#946;+and+BMP+signaling+in+cardiac+cushion+formation:+lessons+from+mice+and+chicken.">TGF&#946; and BMP signaling in cardiac cushion formation: lessons from mice and chicken.</a> Differentiation; research in biological diversity. 84 (1), 89-102 (2012).</li><li>Lieber, S. C., Kruithof, B. P. T., Aubry, N., Vatner, S. F., Gaussin, V. <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+a+miniature+tissue+culture+system+to+culture+mouse+heart+valves.">Design of a miniature tissue culture system to culture mouse heart valves.</a> Annals of biomedical engineering. 38 (3), 674-682 (2010).</li></ol>

The authors declare no conflicts of interest.

Kritischen Schritte in Züchten der Herz Maus Ventile gehört es, die Zeit zwischen dem Herausschneiden des Herzens von der Maus und der Ligation in der Perfusionskammer so kurz wie möglich, um die Lebensfähigkeit und die Ligation der Nadeln senkrecht zu den Ventilen zu gewährleisten richtige Richtung der Strömung zu gewährleisten . Zusätzlich Überwachen von Durchfluss nach der Ligation in der Perfusionskammer ohne Medium gewährleistet eine ordnungsgemäße Einsetzen und Unterbindung der Nadeln. Es ist kritisch,...

Herzklappenerkrankungen ist eine der Hauptursachen für Morbidität und Mortalität in der westlichen Welt; die Prävalenz steigt mit dem Alter, und es wirkt sich auf mehr als 10% der Bevölkerung 75 Jahre und älter 1. Die Ventile des systemischen Teil des Herzens, die Aorten- und Mitralklappen Besonders betroffen sind. Herzklappenkrankheit wird durch den Verlust des hochorganisierte Struktur der Ventile, die in der Veränderung der mechanischen Eigenschaften 2 Ergebnisse aus. Die strukturelle Integrität ist daher entscheidend für die Funktion des Ventils. Die Blättchen des Ventils sind der Klappen interstitiellen Zellen (VIC), Herzklappen Endothelzellen (VEC) und extrazelluläre Matrix, die besonders in einem geschichteten Muster 3,4 organisiert besteht. Die VICs sind für den ECM-Synthese, Abbau und Organisation verantwortlich. Faktoren aus dem Blut, ECs ausgeht oder mit Wohnsitz in der ECM wirken auf die VICs Orchestrierung seiner Funktion. Außerdem,mechanische Kräfte auf das Flugblatt wirken während des Herzzyklus, was zu laminaren oder oszillierende Scherbelastung, Druck- oder Zugspannungen Beeinflussung des Verhaltens von VICs 5. Um zu verstehen, wie die Struktur des Ventils reguliert wird, muss es zunächst zu verstehen, wie VICs der vielfältigen Anzahl von Einflüssen während des Herzzyklus reagieren könnte. In vitro-Studien haben sehr informativ über die Eigenschaften und Fähigkeiten der Klappenzellen. Die Antwort dieser Zellen in vitro können jedoch nicht immer genau imitieren das in vivo Verhalten 6; beispielsweise ist die Reaktion auf Reize VIC abhängig von der Anwesenheit von ECs und ECM-Zusammensetzung 5. Ferner das Ansprechen der Klappen Zellen auf Stimuli, hängt von ihrer bestimmten Stelle in dem Merkblatt 7. Neben biochemische Reize wird das Verhalten der Zellen, die durch Klappenbetätigung O mechanische Kräfte bestimmtn das Ventil 8. Jeder Bereich des Ventils ist mit ihrem eigenen spezifischen Satz hämodynamische Beanspruchungen ausgesetzt. Obwohl aktuelle Ex-vivo-Modelle haben gezeigt, daß mechanische Kräfte sind wichtige Determinanten Klappenstruktur 5 sind die zugehörigen Mechanismen noch nicht geklärt. Während in vivo-Modellen haben Einblick in die molekularen Mechanismen Klappenentwicklung 9,10 zugrunde liegenden vorgesehen ist Einblicke in Erwachsenen Klappen Biologie noch völlig unklar. Daher wurde ein ex vivo Strömungsmodell entwickelt, in denen die Herzklappen in ihrer natürlichen Position im Herzen für einen längeren Zeitraum 11 kultiviert werden. Dies hat den Vorteil, dass die Ventile bleiben in ihrer natürlichen Konfiguration und VICS erfahren derselben Umgebung wie in vivo, wodurch die VICs Reaktionen auf Reize so natürlich wie möglich ist. Zusätzlich kann die Kultur der Ventile in ihrer natürlichen Position im Herzen ermöglicht Werfen jedesKlappenregion an die zuständigen hämodynamische Beanspruchungen. In dieser ex vivo-Modell, das heißt der Miniatur Gewebekultursystem (MTCS) der Ventile kann auf verschiedene biochemische und hämodynamischen Reize ermöglicht die Untersuchung von deren Rolle im Herzklappen Umbau unterzogen werden.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Dulbecco&#8217;s Modified Eagle Medium</td>
			<td>life technolgies</td>
			<td>10569-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>life technolgies</td>
			<td>26140</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin-Transferrin-Selenium</td>
			<td>life technolgies</td>
			<td>41400-045</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic</td>
			<td>life technolgies</td>
			<td>15240-06</td>
			<td></td>
		</tr>
		<tr>
			<td>Silk 7-0</td>
			<td>Ethicon</td>
			<td>768G</td>
			<td></td>
		</tr>
		<tr>
			<td>100 mm culture dish</td>
			<td>Greiner bio-one</td>
			<td>664160</td>
			<td></td>
		</tr>
		<tr>
			<td>50 ml tube</td>
			<td>Greiner bio-one</td>
			<td>227261</td>
			<td></td>
		</tr>
		<tr>
			<td>5 ml syringe</td>
			<td>BD</td>
			<td>309649</td>
			<td></td>
		</tr>
		<tr>
			<td>21 G needle</td>
			<td>BD</td>
			<td>304432</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>LEO</td>
			<td>012866-08</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Fine Science Tools</td>
			<td>11295-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Micro Scissors, Economy, Vannas-type</td>
			<td>Tedpella</td>
			<td>1346</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicon tubing</td>
			<td>Thermo Scientific</td>
			<td>8060-0020</td>
			<td>I.D. x O.D. x Wall: 1.59 x 3.18 x 0.79 mm</td>
		</tr>
		<tr>
			<td>Silicon tubing for pump</td>
			<td>Masterflex</td>
			<td>96400-13</td>
			<td>I.D. x O.D. x Wall: 0,8 x1,59 x 0,40 mm</td>
		</tr>
		<tr>
			<td>Biocompatible glue (Histoacryl)</td>
			<td>B. Braun</td>
			<td>1050071</td>
			<td></td>
		</tr>
		<tr>
			<td>precision vaporizer</td>
			<td>Dr&#228;ger</td>
			<td>Vapor 200</td>
			<td></td>
		</tr>
		<tr>
			<td>peristaltic roller pump</td>
			<td>Masterflex</td>
			<td>7521-35</td>
			<td></td>
		</tr>
		<tr>
			<td>Easy-load pump head</td>
			<td>Masterflex</td>
			<td>7518-00</td>
			<td></td>
		</tr>
		<tr>
			<td>Flow chamber</td>
			<td></td>
			<td></td>
			<td>see Lieber et al., 2010</td>
		</tr>
		<tr>
			<td>Bubble trap</td>
			<td></td>
			<td></td>
			<td>see Lieber et al., 2010</td>
		</tr>
	</tbody>
</table>

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.

Die Aortenklappe (Abbildung 2) oder Mitralklappe 11 kann für mindestens 3 Tage kultiviert werden. Durch Kultivierung in der offenen Stellung (die den systolischen Position für die Aortenklappe und der diastolischen Position für die Mitralklappe darstellt), Herzklappen Zellen lebensfähig bleiben. Kein Zelltod beobachtet, wie durch die Abwesenheit von TUNEL-positiven Zellen (2H, I) oder gespalten Caspase-3-Expression bestimmt (nicht gezeigt, und Lieber et al.,<...

Watch this Scientific Journal Video about Culturing Mouse Cardiac Valves in the Miniature Tissue Culture System at JoVE.com

Culturing Mouse Cardiac Valves in the Miniature Tissue Culture System

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.

Kultivierung von Maus-Herzklappen in der Miniatur-Gewebekultursystem

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 ...

culturing-mouse-cardiac-valves-in-the-miniature-tissue-culture-system

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8.7K Aufrufe.  Leiden University Medical Center. 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.

Serie: Culturing Mouse Cardiac Valves in the Miniature Tissue Culture System

A Method for Ovarian Follicle Encapsulation and Culture in a Proteolytically Degradable 3 Dimensional System

The ovarian follicle is the functional unit of the ovary that secretes sex hormones and supports oocyte maturation. In vitro follicle techniques provide a tool to model follicle development in order to investigate basic biology, and are further being developed as a technique to preserve fertility in the clinic1-4. Our in vitro culture system employs hydrogels in order to mimic the native ovarian environment by maintaining the 3D follicular architecture, cell-cell interactions and paracrine signaling that direct follicle development 5. Previously, follicles were successfully cultured in alginate, an inert algae-derived polysaccharide that undergoes gelation with calcium ions6-8. Alginate hydrogels formed at a concentration of 0.25% w/v were the most permissive for follicle culture, and retained the highest developmental competence 9. Alginate hydrogels are not degradable, thus an increase in the follicle diameter results in a compressive force on the follicle that can impact follicle growth10. We subsequently developed a culture system based on a fibrin-alginate interpenetrating network (FA-IPN), in which a mixture of fibrin and alginate are gelled simultaneously. This combination provides a dynamic mechanical environment because both components contribute to matrix rigidity initially; however, proteases secreted by the growing follicle degrade fibrin in the matrix leaving only alginate to provide support. With the IPN, the alginate content can be reduced below 0.25%, which is not possible with alginate alone 5. Thus, as the follicle expands, it will experience a reduced compressive force due to the reduced solids content. Herein, we describe an encapsulation method and an in vitro culture system for ovarian follicles within a FA-IPN. The dynamic mechanical environment mimics the natural ovarian environment in which small follicles reside in a rigid cortex and move to a more permissive medulla as they increase in size11. The degradable component may be particularly critical for clinical translation in order to support the greater than 106-fold increase in volume that human follicles normally undergo in vivo .

A new method for ovarian follicle encapsulation in a 3D fibrin-alginate interpenetrating network is described. This system combines structural support with proteolytic degradation to support the development of immature follicles to produce mature oocytes. This method may be applied to culture cell aggregates to maintain cell-cell contacts without limiting expansion.

Eine Methode zur Ovarialfollikel Encapsulation und Kultur in einem Proteolytisch Degradable 3 Dimensional-System

The ovarian follicle is the functional unit of the ovary that secretes sex hormones and supports oocyte maturation. In vitro  follicle techniques provide ...

Forschung

Biotechnik

Encapsulation of Cardiomyocytes in a Fibrin Hydrogel for Cardiac Tissue Engineering

Culturing cells in a three dimensional hydrogel environment is an important technique for developing constructs for tissue engineering as well as studying cellular responses under various culture conditions in vitro. The three dimensional environment more closely mimics what the cells observe in vivo due to the application of mechanical and chemical stimuli in all dimensions 1. Three-dimensional hydrogels can either be made from synthetic polymers such as PEG-DA 2 and PLGA 3 or a number of naturally occurring proteins such as collagen 4, hyaluronic acid 5 or fibrin 6,7. Hydrogels created from fibrin, a naturally occurring blood clotting protein, can polymerize to form a mesh that is part of the body's natural wound healing processes 8. Fibrin is cell-degradable and potentially autologous 9, making it an ideal temporary scaffold for tissue engineering.
Here we describe in detail the isolation of neonatal cardiomyocytes from three day old rat pups and the preparation of the cells for encapsulation in fibrin hydrogel constructs for tissue engineering. Neonatal myocytes are a common cell source used for in vitro studies in cardiac tissue formation and engineering 4. Fibrin gel is created by mixing fibrinogen with the enzyme thrombin. Thrombin cleaves fibrinopeptides FpA and FpB from fibrinogen, revealing binding sites that interact with other monomers 10. These interactions cause the monomers to self-assemble into fibers that form the hydrogel mesh. Because the timing of this enzymatic reaction can be adjusted by altering the ratio of thrombin to fibrinogen, or the ratio of calcium to thrombin, one can injection mold constructs with a number of different geometries 11,12. Further we can generate alignment of the resulting tissue by how we constrain the gel during culture 13.
After culturing the engineered cardiac tissue constructs for two weeks under static conditions, the cardiac cells have begun to remodel the construct and can generate a contraction force under electrical pacing conditions 6. As part of this protocol, we also describe methods for analyzing the tissue engineered myocardium after the culture period including functional analysis of the active force generated by the cardiac muscle construct upon electrical stimulation, as well as methods for determining final cell viability (Live-Dead assay) and immunohistological staining to examine the expression and morphology of typical proteins important for contraction (Myosin Heavy Chain or MHC) and cellular coupling (Connexin 43 or Cx43) between myocytes.

We describe the isolation of neonatal cardiomyocytes and the preparation of the cells for encapsulation in fibrin hydrogel constructs for tissue engineering. We describe methods for analyzing the tissue engineered myocardium after the culture period including active force generated upon electrical stimulation and cell viability and immunohistological staining.

Verkapselung von Kardiomyozyten in einer Fibrin-Hydrogel für Cardiac Tissue Engineering

Culturing cells in a three dimensional hydrogel environment is an important technique for developing constructs for tissue engineering as well as studying ...

Capillary Force Lithography for Cardiac Tissue Engineering

Cardiovascular disease remains the leading cause of death worldwide1. Cardiac tissue engineering holds much promise to deliver groundbreaking medical discoveries with the aims of developing functional tissues for cardiac regeneration as well as in vitro screening assays. However, the ability to create high-fidelity models of heart tissue has proven difficult. The heart&#8217;s extracellular matrix (ECM) is a complex structure consisting of both biochemical and biomechanical signals ranging from the micro- to the nanometer scale2. Local mechanical loading conditions and cell-ECM interactions have recently been recognized as vital components in cardiac tissue engineering3-5.
A large portion of the cardiac ECM is composed of aligned collagen fibers with nano-scale diameters that significantly influences tissue architecture and electromechanical coupling2. Unfortunately, few methods have been able to mimic the organization of ECM fibers down to the nanometer scale. Recent advancements in nanofabrication techniques, however, have enabled the design and fabrication of scalable scaffolds that mimic the in vivo structural and substrate stiffness cues of the ECM in the heart6-9.
Here we present the development of two reproducible, cost-effective, and scalable nanopatterning processes for the functional alignment of cardiac cells using the biocompatible polymer poly(lactide-co-glycolide) (PLGA)8 and a polyurethane (PU) based polymer. These anisotropically nanofabricated substrata (ANFS) mimic the underlying ECM of well-organized, aligned tissues and can be used to investigate the role of nanotopography on cell morphology and function10-14.
Using a nanopatterned (NP) silicon master as a template, a polyurethane acrylate (PUA) mold is fabricated. This PUA mold is then used to pattern the PU or PLGA hydrogel via UV-assisted or solvent-mediated capillary force lithography (CFL), respectively15,16. Briefly, PU or PLGA pre-polymer is drop dispensed onto a glass coverslip and the PUA mold is placed on top. For UV-assisted CFL, the PU is then exposed to UV radiation (&#955; = 250-400 nm) for curing. For solvent-mediated CFL, the PLGA is embossed using heat (120 &#176;C) and pressure (100 kPa). After curing, the PUA mold is peeled off, leaving behind an ANFS for cell culture. Primary cells, such as neonatal rat ventricular myocytes, as well as human pluripotent stem cell-derived cardiomyocytes, can be maintained on the ANFS2.

In this protocol, we demonstrate the fabrication of biomimetic cardiac cell culture substrata made from two distinct polymeric materials using capillary force lithography. The described methods provide a scalable, cost-effective technique to engineer the structure and function of macroscopic cardiac tissues for in vitro and in vivo applications.

Kapillar-Force-Lithographie für Herz-Tissue Engineering

Cardiovascular disease remains the leading cause of death worldwide1. Cardiac tissue engineering holds much promise to deliver groundbreaking medical ...

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

A detailed understanding of the complexity and relative variability within the human cardiac venous system is crucial for the development of cardiac devices that require access to these vessels. For example, cardiac venous anatomy is known to be one of the key limitations for the proper delivery of cardiac resynchronization therapy (CRT)1 Therefore, the development of a database of anatomical parameters for human cardiac venous systems can aid in the design of CRT delivery devices to overcome such a limitation. In this research project, the anatomical parameters were obtained from 3D reconstructions of the venous system using contrast-computed tomography (CT) imaging and modeling software (Materialise, Leuven, Belgium). The following parameters were assessed for each vein: arc length, tortuousity, branching angle, distance to the coronary sinus ostium, and vessel diameter.
	CRT is a potential treatment for patients with electromechanical dyssynchrony. Approximately 10-20% of heart failure patients may benefit from CRT2. Electromechanical dyssynchrony implies that parts of the myocardium activate and contract earlier or later than the normal conduction pathway of the heart. In CRT, dyssynchronous areas of the myocardium are treated with electrical stimulation. CRT pacing typically involves pacing leads that stimulate the right atrium (RA), right ventricle (RV), and left ventricle (LV) to produce more resynchronized rhythms. The LV lead is typically implanted within a cardiac vein, with the aim to overlay it within the site of latest myocardial activation. 
	We believe that the models obtained and the analyses thereof will promote the anatomical education for patients, students, clinicians, and medical device designers. The methodologies employed here can also be utilized to study other anatomical features of our human heart specimens, such as the coronary arteries. To further encourage the educational value of this research, we have shared the venous models on our free access website: <a href="http://www.vhlab.umn.edu/atlas" target="_blank">www.vhlab.umn.edu/atlas</a>.

The objective of this research is to recreate and then access the anatomy of the human cardiac venous system using 3D reconstructions generated from contrast-computed tomography scans.

Anatomische Rekonstruktionen des menschlichen Cardiac Venensystem mit Kontrast-Computertomographie Perfusion-fixierten Proben

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

Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

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

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

Protokoll für Relative Hydrodynamische Beurteilung der Tri-Polymer Merkblatt Ventile

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

Tissue Engineering of a Human 3D in vitro Tumor Test System

Cancer is one of the leading causes of death worldwide. Current therapeutic strategies are predominantly developed in 2D culture systems, which inadequately reflect physiological conditions in vivo. Biological 3D matrices provide cells an environment in which cells can self-organize, allowing the study of tissue organization and cell differentiation. Such scaffolds can be seeded with a mixture of different cell types to study direct 3D cell-cell-interactions. To mimic the 3D complexity of cancer tumors, our group has developed a 3D in vitro tumor test system.	
	Our 3D tissue test system models the in vivo situation of malignant peripheral nerve sheath tumors (MPNSTs), which we established with our decellularized porcine jejunal segment derived biological vascularized scaffold (BioVaSc). In our model, we reseeded a modified BioVaSc matrix with primary fibroblasts, microvascular endothelial cells (mvECs) and the S462 tumor cell line. For static culture, the vascular structure of the BioVaSc is removed and the remaining scaffold is cut open on one side (Small Intestinal Submucosa SIS-Muc). The resulting matrix is then fixed between two metal rings (cell crowns).	
	Another option is to culture the cell-seeded SIS-Muc in a flow bioreactor system that exposes the cells to shear stress. Here, the bioreactor is connected to a peristaltic pump in a self-constructed incubator. A computer regulates the arterial oxygen and nutrient supply via parameters such as blood pressure, temperature, and flow rate. This setup allows for a dynamic culture with either pressure-regulated pulsatile or constant flow.	
	In this study, we could successfully establish both a static and dynamic 3D culture system for MPNSTs. The ability to model cancer tumors in a more natural 3D environment will enable the discovery, testing, and validation of future pharmaceuticals in a human-like model.

Tissue Engineering of a Human 3D in vitro Tumor Test System

Methods to create human 3D tumor tissues as test systems are described. These technologies are based on a decellularized Biological Vascularized Scaffold (BioVaSc), primary human cells and a tumor cell line, which can be cultured under static as well as under dynamic conditions in a flow bioreactor.

Tissue Engineering eines Menschen 3D<em&gt; In-vitro-</em&gt; Tumor-Testsystem

Cancer is one of the leading causes of death worldwide.  Current therapeutic strategies are predominantly developed in 2D culture  systems, which ...

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and dampen loads in the spine. The IVD consists of a proteoglycan-rich nucleus pulposus (NP) and a collagen-rich annulus fibrosis (AF) sandwiched by cartilaginous end-plates. Together with the adjacent vertebrae, the vertebrae-IVD structure forms a functional spine unit (FSU). These microstructures contain unique cell types as well as unique extracellular matrices. Whole organ culture of the FSU preserves the native extracellular matrix, cell differentiation phenotypes, and cellular-matrix interactions. Thus, organ culture techniques are particularly useful for investigating the complex biological mechanisms of the IVD. Here, we describe a high-throughput approach for culturing whole lumbar mouse FSUs that provides an ideal platform for studying disease mechanisms and therapies for the IVD. Furthermore, we describe several applications that utilize this organ culture method to conduct further studies including contrast-enhanced microCT imaging and three-dimensional high-resolution finite element modeling of the IVD.

An In Vitro Organ Culture Model of the Murine Intervertebral Disc

Whole organ culture of the intervertebral disc (IVD) preserves the native extracellular matrix, cell phenotypes, and cellular-matrix interactions. Here we describe an IVD culture system using mouse lumbar and caudal IVDs in their functional spinal units and several applications utilizing this system.

Ein<em&gt; In Vitro</em&gt; Organ Culture Modell der Murine Bandscheiben

Intervertebral disc (IVD) degeneration is a significant contributor to low back pain. The IVD is a fibrocartilaginous joint that serves to transmit and ...

Culturing Mammalian Cells in Three-dimensional Peptide Scaffolds

A useful technique for culturing cells in a self-assembling nanofiber three-dimensional (3D) scaffold is described. This culture system recreates an environment that closely mimics the structural features of non-polarized tissue. Furthermore, the particular intrinsic nanofiber structure of the scaffold makes it transparent to visual light, which allows for easy visualization of the sample under microscopy. This advantage was largely used to study cell migration, organization, proliferation, and differentiation and thus any development of their particular cellular function by staining with specific dyes or probes. Furthermore, in this work, we describe the good performance of this system to easily study the redifferentiation of expanded human articular chondrocytes into cartilaginous tissue. Cells were encapsulated into self-assembling peptide scaffolds and cultured under specific conditions to promote chondrogenesis. Three-dimensional cultures showed good viability during the 4 weeks of the experiment. As expected, samples cultured with chondrogenic inducers (compared to non-induced controls) stained strongly positive for toluidine blue (which stains glycosaminoglycans (GAGs) that are highly present in cartilage extracellular matrix) and expressed specific molecular markers, including collagen type I, II and X, according to Western Blot analysis. This protocol is easy to perform and can be used at research laboratories, industries and for educational purposes in laboratory courses.

Here, we present a protocol to obtain 3D-culture systems in self-assembling peptide scaffolds to promote the differentiation of dedifferentiated human articular chondrocytes into cartilage-like tissue.

Kultivierung von Säugerzellen in dreidimensionale Peptid Gerüste

A useful technique for culturing cells in a self-assembling nanofiber three-dimensional (3D) scaffold is described. This culture system recreates an ...

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.

Eine Net Schimmel basierende Methode der dreidimensionalen Gerüst-freie Herzgewebe Schöpfung

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

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.

Biaxiale mechanische Charakterisierung von ventrikulären Herzklappen

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