Una sovvenzione seme della University of Florida - College of Medicine è riconosciuto con gratitudine. Studi universitari (Manuel Salinas) sono stati sostenuti attraverso una opportunità di minoranza di programmi di ricerca biomedica - iniziativa di ricerca per la valorizzazione scientifica (MBR-RISE) borsa: NIH / NIGMS R25 GM061347. Il sostegno finanziario della Wallace H. Coulter Fondazione attraverso la Florida International University, Dipartimento di Ingegneria Biomedica è anche riconosciuto con gratitudine. Infine, gli autori ringraziano i seguenti studenti per la loro assistenza durante le varie fasi del processo sperimentale: Kamau Pier, Malachia Suttle, Kendall Armstrong e Abraham Alfonso.

1. Preparazione <ol><li> Progettare e fabbricare un assieme per ospitare una geometria valvola tri-foglio. Questo sarà come minimo includere un supporto valvola di sutura-nei lembi della valvola ed un tubo per ospitare il titolare valvola e accessori circostanti per fissare il gruppo sul sistema di duplicazione di impulso. Nel nostro caso, abbiamo utilizzato un sistema di duplicazione di impulsi disponibile in commercio disponibile da ViVitro Labs Inc. (Victoria, BC). Disegno del supporto della valvola così come le configurazioni di pre e post montaggio sono descritte nella Figura 1. </li><li> L&#39;intero ciclo dovrà essere trattato con primer prima dell&#39;uso. Questo comporta due fasi: i) la pulizia di tutto il sistema ciclo usando soluzione di acqua e sapone, compresa la sostituzione di qualsiasi provetta degradate prima dell&#39;uso e ii) la taratura degli strumenti collegati al loop, cioè la pompa utilizzata, la sonda di mandata, e i trasduttori di pressione (generalmente misurata a atriale, aortica e ventricolare sedi). La calibrazione può initbuona resa eseguire utilizzando soluzione fisiologica 1% e deve essere ripetuto prima di usare sangue-analogico soluzione di glicerina. </li></ol> 2. Nativo della valvola aortica Dissezione <ol><li> Ottenere 4 freschi cuori di maiale con l&#39;aorta intatto da un USDA macello (Institutional Animal Care ed uso Comitato (IACUC) approvazione può essere richiesto). Nel nostro caso, il nostro protocollo di dissezione è stato approvato dal IACUC presso la Florida International University (protocollo numero di omologazione: 11-020). Sciacquare il cuore con acqua deionizzata e metterla in un recipiente pieno di antimicotico / antibiotico e sterile fosfato 1% soluzione salina tamponata (PBS), soluzione e il trasporto sul ghiaccio per il laboratorio di analisi idrodinamica. </li><li> Mettere i cuori in una padella dissezione e rimuovere con attenzione il pericardio. Posizionare il cuore in modo tale che faccia ventrale si sta affrontando. Controllare visivamente e identificare le quattro camere del cuore e individuare l&#39;arco aortico sull&#39;aorta intatta. </li><li> Separare il cuore in two dimezza tagliando attraverso orizzontalmente a circa 0,75 nel seguito l&#39;annulus, cioè la giunzione tra l&#39;aorta e il ventricolo sinistro. Isolare accuratamente l&#39;aorta intatta ancora attaccato al segmento di tessuto ventricolare sinistra. </li><li> Esaminare la valvola aortica si trova nella radice aortica, la regione tra l&#39;aorta ascendente e l&#39;annulus inferiore, garantendo che non vi è alcun danno o segni di calcificazione. </li><li> Dividere dell&#39;aorta a ~ 1 supra dell&#39;anulus e separare il segmento tessuto ventricolare sinistro sotto l&#39;annulus da isolare la valvola aortica (Figura 2a). </li></ol> 3. Polymer e nativi Processo sutura Valve <ol><li> Posizionare la valvola cardiaca all&#39;interno del supporto valvola tale che la base di ogni valvola allinea con la base del palo titolare. Fissare la valvola in posizione di ogni post temporaneamente con una graffetta, ma attenzione a non danneggiare le commissure o le cuspidi. </li><li> Inserire la sutura nelladell&#39;ago. Iniziare sutura sul fondo del titolare valvola facendo passare l&#39;ago attraverso il primo foro, dall&#39;esterno verso l&#39;interno in modo che l&#39;ago può essere estratto dal fondo. In modo loop, avviare la sutura della valvola verticalmente i pali del titolare della valvola. </li><li> Progressi con sutura (Figura 2b) lungo la circonferenza del supporto e fissare con sutura aggiuntivo intorno le punte dei messaggi titolare. Graffette (figura 2c) possono essere rimossi quando la valvola è completamente garantita con suture ai 3 posti e alla circonferenza del supporto della valvola (figure 2d e 2e). </li></ol> 4. La valutazione idrodinamica Nota: protocollo effettiva varia a seconda del sistema di duplicazione di impulso specifico utilizzato. Tutte le informazioni caontained qui utilizzato il ViVitro Pulse Duplicator Sysytem (ViVitro Labs, Inc., Vancouver, BC). <ol><li> Bi-volantino vaLVE <ol><li> Impostare la frequenza cardiaca del sistema di duplicazione di impulsi a 70 battiti / min. </li><li> Selezionare una forma d&#39;onda di flusso per azionare la pompa (nel caso del sistema ViVitro la forma d&#39;onda S35 è stata scelta per tutti i test idrodinamici). La forma d&#39;onda specifica utilizzata nei nostri esperimenti è illustrato da (2001) Lim et al. 17. </li><li> Accendere amplificatore e pompa a pistoni. Riscaldare per 15 minuti. </li><li> Luogo valvola bi-leaflet (figura 2f) in posizione aortica. </li><li> Spalmare grasso per vuoto su tutti i nodi del dispositivo su cui potrebbero verificarsi perdite. </li><li> Versare glicerina / liquido salina nel vano atriale. Notare che il sistema di duplicazione pulsatile gira su 2 L di liquido con: 35% / 0,7 L glicerina e 65% / 1,3 L di soluzione salina. La soluzione salina è preparato utilizzando sale comune ben disciolto in acqua deionizzata alla concentrazione di 9 mg / ml (peso / volume). </li><li> Accendere il trasduttore di flusso che è stato inserito nella posizione aortica. </li><li> Calibrare Thpompa e. </li><li> Procedere con la calibrazione del trasduttore di flusso seguito dai trasduttori di pressione. Analogamente alla pompa, è sufficiente seguire le istruzioni fornite dal software ViVitest (ViVitro Labs Inc.) per ogni flusso e la pressione sotto la scheda calibrare. </li><li> Una volta completata la calibrazione, avviare la pompa ad un basso numero di giri fino a quando il liquido riempie il vano aortica. Controllare eventuali perdite. Utilizzare ulteriore grasso per vuoto, se necessario. </li><li> Ruotare i due rubinetti di arresto (aortica e trasduttori ventricolari) in posizione aperta. </li><li> Aumentare il numero di giri della pompa fino a quando il volume della corsa raggiunge 80 ml / battito. </li><li> Permettere al sistema di funzionare per 10 minuti fino a quando il flusso si è stabilizzato. Stabilizzazione del flusso può essere verificato osservando il flusso e la pressione forme d&#39;onda visualizzate nella schermata. Basso a nullo variazione tra i cicli è un buon indicatore della stabilizzazione del sistema. </li><li> Nel software ViVitest selezionare la modalità di acquisizione. </li><li> Clicca su raccogliere 10 cicli. </li><li> Dalla modalità analizzare, cleccare sul tavolo e salvare il file. Anche salvare un&#39;immagine delle forme d&#39;onda utilizzando l&#39;opzione di foto-snap in ViVitest. </li></ol></li><li> Valvole native e Polymer <ol><li> Per valvole di polimeri e animale, seguire la stessa procedura 3.1.1 - 3.1.3 delle istruzioni della valvola bi-leaflet. </li><li> Posizionare il supporto della valvola con la valvola di sutura all&#39;interno del tubo di vetro dal gruppo su misura. Sandwich il tubo con i pezzi superiore e inferiore e sicure sul posto con viti laterali e dadi. </li><li> Luogo di montaggio tra la camera aortica e il titolare della valvola aortica originale. </li><li> Continuare con i passaggi 3.1.5 - 3.1.16 dalle istruzioni della valvola bi-leaflet. </li></ol></li></ol> 5. Post Processing <ol><li> Portata e forme d&#39;onda di pressione <ol><li> Media i dati raccolti per ciascuna delle forme d&#39;onda raccolta, vale a dire pressione aortica (AP), pressione ventricolare (VP) e portata (Q). </li><li> Per ciascun gruppo di valvola (polimero, suina nvalvola aortica ative e bi-foglio illustrativo), tracciare la corrispondente AP, VP e Q rispetto a relazioni di tempo sullo stesso appezzamento. </li><li> Per l&#39;AP, sovrapporre, valvola aortica nativa normale 18, e bi-leaflet protesi valvolare 19 appezzamenti dalla letteratura per la convalida. </li></ol></li><li> Parametri idrodinamici <ol><li> Per ogni valvola testata, i seguenti parametri idrodinamici devono essere calcolati: a) Caduta di pressione del flusso e della pressione transvalvolare massima (TVP), b) la radice aortica quadratico medio (RMS) portata avanti, c) il flusso in avanti aortica, chiusura, perdite e totale volume di rigurgito, d) valvola di fine area dell&#39;orifizio (EOA), e) transaortico avanti di flusso, di chiusura, di dispersione e le perdite di energia totale. <ol><li> Caduta di pressione del flusso è calcolato da letture di TVP e possono essere classificati in tre intervalli di tempo, P: intervallo che inizia e finisce con 0 TVP, F: intervallo con mandata e H: intervallo inizia con 0 TVP e termina con 0 flusso. Massima TVP è la magradiente di pressione ximum registrata attraverso la valvola aortica e dalla lettura della pressione ventricolare. </li><li> La RMS portata avanti (Q RMS) fornisce un parametro utile per quantificare l&#39;entità della portata avanti nel modo seguente: <img alt="Equazione 1" fo:src="/files/ftp_upload/50335/50335eq1highres.jpg" src="/files/ftp_upload/50335/50335eq1.jpg" /> Dove &#39;n&#39; è il numero totale di punti di tempo raccolto, &#39;Q i&#39; è la misura di portata istantanea raccolte per &#39;i&#39;. </li><li> Il aortica in avanti, di chiusura e di dispersione dei volumi sono calcolati in base ai seguenti intervalli di tempo, Attacco: inizio di flusso in avanti attraverso la valvola (t o), alla fine del flusso in avanti (t 1); Chiusura: da t 1 fino all&#39;istanza Valvola di chiusura (t 2); dispersione: da t 2 fino alla fine del ciclo cardiaco (t 3). Volume di rigurgito totale è semplicemente la somma di closing e volumi di dispersione. </li><li> L&#39;EOA in base alle proprietà del sangue può essere calcolato per i 3 intervalli, P, F e H della TVP media durante ciascuno di questi periodi come 20: <img alt="Equazione 1" fo:src="/files/ftp_upload/50335/50335eq2highres.jpg" src="/files/ftp_upload/50335/50335eq2.jpg" /></li><li> Perdite di energia sono definiti come segue 21: <img alt="Equazione 1" fo:src="/files/ftp_upload/50335/50335eq3highres.jpg" src="/files/ftp_upload/50335/50335eq3.jpg" /></li></ol></li></ol></li></ol>

<ol>
	<li>Rajamannan, N. M., 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=Calcific+aortic+valve+disease:+not+simply+a+degenerative+process:+A+review+and+agenda+for+research+from+the+National+Heart+and+Lung+and+Blood+Institute+Aortic+Stenosis+Working+Group.+Executive+summary:+Calcific+aortic+valve+disease-2011+update.">Calcific aortic valve disease: not simply a degenerative process: A review and agenda for research from the National Heart and Lung and Blood Institute Aortic Stenosis Working Group. Executive summary: Calcific aortic valve disease-2011 update.</a> Circulation. 124, 1783-1791 (2011).</li><li>Marijon, E., Mirabel, M., Celermajer, D. S., Jouven, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rheumatic+heart+disease.">Rheumatic heart disease.</a> Lancet. 379, 953-964 (2012).</li><li>Karaci, A. R., 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=Surgical+treatment+of+infective+valve+endocarditis+in+children+with+congenital+heart+disease.">Surgical treatment of infective valve endocarditis in children with congenital heart disease.</a> J. Card. Surg. 27, 93-98 (2012).</li><li>Knirsch, W., Nadal, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infective+endocarditis+in+congenital+heart+disease.">Infective endocarditis in congenital heart disease.</a> Eur. J. Pediatr. 170, 1111-1127 (2011).</li><li>Korossis, S. A., Fisher, J., Ingham, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+valve+replacement:+a+bioengineering+approach.">Cardiac valve replacement: a bioengineering approach.</a> Biomed. Mater. Eng. 10, 83-124 (2000).</li><li>Ghanbari, H., 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=Polymeric+heart+valves:+new+materials,+emerging+hopes.">Polymeric heart valves: new materials, emerging hopes.</a> Trends Biotechnol. 27, 359-367 (2009).</li><li>Mol, A., Smits, A. I., Bouten, C. V., Baaijens, F. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+engineering+of+heart+valves:+advances+and+current+challenges.">Tissue engineering of heart valves: advances and current challenges.</a> Expert Rev. Med. Devices. 6, 259-275 (2009).</li><li>Ramaswamy, 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=The+role+of+organ+level+conditioning+on+the+promotion+of+engineered+heart+valve+tissue+development+in+using+mesenchymal+stem+cells.">The role of organ level conditioning on the promotion of engineered heart valve tissue development in using mesenchymal stem cells.</a> Biomaterials. 31, 1114-1125 (2010).</li><li>Sacks, M. S., Schoen, F. J., Mayer, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioengineering+challenges+for+heart+valve+tissue+engineering.">Bioengineering challenges for heart valve tissue engineering.</a> Annu. Rev. Biomed. Eng. 11, 289-313 (2009).</li><li>Zamorano, J. L., 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=EAE/ASE+recommendations+for+the+use+of+echocardiography+in+new+transcatheter+interventions+for+valvular+heart+disease.">EAE/ASE recommendations for the use of echocardiography in new transcatheter interventions for valvular heart disease.</a> J. Am. Soc. Echocardiogr. 24, 937-965 (2011).</li><li>ANSI/AAMI/ISO. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+Implants+-+Cardiac+Valve+Prostheses.">Cardiovascular Implants - Cardiac Valve Prostheses.</a> Assoc. Adv. Med. Instrum. 71, (2005).</li><li>Gallocher, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Durability Assessment of Polymer Trileaflet Heart Valves PhD thesis. , 313 (2007).</li><li>Carroll, R., Boggs, T., Yamaguchi, H., Al-Mously, F., DeGroff, C., Tran-Son-Tay, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood+Cell+Adhesion+on+Polymeric+Heart+Valves.">Blood Cell Adhesion on Polymeric Heart Valves.</a> , (2012).</li><li>Pierre, K. K., Salinas, M., Carroll, R., Landaburo, K., Yamaguchi, H., DeGroff, C., Al-Mousily, F., Bleiweis, M., Ramaswamy, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrodynamic+Evaluation+of+a+Novel+Tri-Leaflet+Silicone+Heart+Valve+Prosthesis.">Hydrodynamic Evaluation of a Novel Tri-Leaflet Silicone Heart Valve Prosthesis.</a> , (2012).</li><li>Cacciola, G., Peters, G. W., Schreurs, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+three-dimensional+mechanical+analysis+of+a+stentless+fibre-reinforced+aortic+valve+prosthesis.">A three-dimensional mechanical analysis of a stentless fibre-reinforced aortic valve prosthesis.</a> J. Biomech. 33, 521-530 (2000).</li><li>De Hart, J., Cacciola, G., Schreurs, P. J., Peters, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+three-dimensional+analysis+of+a+fibre-reinforced+aortic+valve+prosthesis.">A three-dimensional analysis of a fibre-reinforced aortic valve prosthesis.</a> J. Biomech. 31, 629-638 (1998).</li><li>Lim, W. L., Chew, Y. T., Chew, T. C., Low, H. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulsatile+flow+studies+of+a+porcine+bioprosthetic+aortic+valve+in+vitro:+PIV+measurements+and+shear-induced+blood+damage.">Pulsatile flow studies of a porcine bioprosthetic aortic valve in vitro: PIV measurements and shear-induced blood damage.</a> J. Biomech. 34, 1417-1427 (2001).</li><li>Gutierrez, C., Blanchard, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diastolic+heart+failure:+challenges+of+diagnosis+and+treatment.">Diastolic heart failure: challenges of diagnosis and treatment.</a> Am. Fam. Physician. 69, 2609-2616 (2004).</li><li>Shi, Y., Yeo, T. J., Zhao, Y., Hwang, N. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Particle+image+velocimetry+study+of+pulsatile+flow+in+bi-leaflet+mechanical+heart+valves+with+image+compensation+method.">Particle image velocimetry study of pulsatile flow in bi-leaflet mechanical heart valves with image compensation method.</a> J. Biol. Phys. 32, 531-551 (2006).</li><li>Chandran, K. B., Yoganathan, A. P., Rittgers, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biofluid Mechanics: The Human Circulation. , 277-314 (2007).</li><li>Akins, C. W., Travis, B., 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=Energy+loss+for+evaluating+heart+valve+performance.">Energy loss for evaluating heart valve performance.</a> J. Thorac. Cardiovasc. Surg. 136, 820-833 (2008).</li><li>Fung, Y. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biomechanics: Circulation. , (1997).</li><li>Keener, J., Sneyd, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Mathematical Physiology, II: Systems Physiology. , (1998).</li><li>Quick, C. M., Berger, D. S., Noordergraaf, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apparent+arterial+compliance.">Apparent arterial compliance.</a> Am. J. Physiol. 274, H1393-H1403 (1998).</li><li>Wang, Q., Jaramillo, F., Kato, Y., Pinchuk, L., Schoephoerster, 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=Hydrodynamic+Evaluation+of+a+Minimally+Invasive+Heart+Valve+in+an+Isolated+Aortic+Root+Using+a+Modified+In+Vitro+Model.">Hydrodynamic Evaluation of a Minimally Invasive Heart Valve in an Isolated Aortic Root Using a Modified In Vitro Model.</a> J. Med. Devices. 3, 011002.1-011002.6 (2009).</li><li>Baldwin, J. T., Campbell, A., Luck, C., Ogilvie, W., Sauter, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluid+dynamics+of+the+CarboMedics+kinetic+bileaflet+prosthetic+heart+valve.">Fluid dynamics of the CarboMedics kinetic bileaflet prosthetic heart valve.</a> Eur. J. Cardiothorac. Surg. 11, 287-292 (1997).</li></ol>

Gli autori non hanno nulla da rivelare.

In questo studio, abbiamo dimostrato l&#39;utilità di modifica di una unità duplicatore pulsatile disponibile in commercio per accogliere valvola tri-opuscolo geometrie in modo che il test idrodinamico del polimero e valvole suine autoctone può essere eseguita. In particolare, nel nostro caso, il sistema è stato modificato un cuore sinistro ViVitro e sistema simulatore sistemica (Figura 1a) controllato tramite il sistema di acquisizione dati ViViTest (ViVitro Systems, Inc, Victoria, BC, Canada). Tut...

Valvulopatia cardiaca spesso deriva da degenerativa calcificazione della valvola 1, la febbre reumatica 2, endocardite 3,4 o difetti congeniti alla nascita. Quando si verifica danno valvola, causando stenosi e / o rigurgito prolasso della valvola e non può essere riparato chirurgicamente, la valvola nativa viene generalmente sostituita da una valvola protesica. Attualmente le opzioni disponibili includono le valvole meccaniche (valvole a gabbia-sfera, valvole a disco inclinabili, ecc.), Homograft e valvole bioprotesiche (suina e bovina valvole). Valvole meccaniche sono spesso raccomandati per i pazienti più giovani in base alla loro durata nel tempo, ma il paziente è richiesto di rimanere in terapia anticoagulante per prevenire le complicanze trombotiche 5. Protesi valvolari homograft e biologiche sono state scelte efficaci per evitare il sangue terapia più sottile, tuttavia, queste valvole hanno elevato rischio di fibrosi, calcificazione, degenerazione, e le complicazioni immunogenico che portano a insufficienza della valvola 6. Valvole tissutale sono oggetto di indagine come una tecnologia emergente 7-9, ma molto resta ancora da scoprire. Sono necessari durevoli, biocompatibili, valvole protesiche alternative per migliorare la qualità della vita dei pazienti affetti da malattie valvolari cardiache. Ancora una volta, questo motivo valvola potrebbe sostituire la bioprotesi utilizzato nella costruzione di valvole transcatetere, con approcci transcatetere mostrano il potenziale per trasformare il trattamento di pazienti selezionati con malattia cardiaca valvolare 10. Come affermato dalle norme vigenti, un successo della valvola cardiaca sostituto dovrebbe avere le seguenti caratteristiche prestazionali: &quot;1) consente il flusso in avanti con accettabilmente piccola goccia media differenza di pressione; 2) impedisce il flusso retrogrado con accettabilmente piccolo rigurgito; 3) resiste embolizzazione; 4) resiste emolisi; 5) resiste alla formazione di trombi; 6) è biocompatibile; 7) è compatibile con le tecniche diagnostiche in vivo; 8) è consegnabile e impiantabile nel targetpopolazione; 9) rimane fissa una volta collocato, 10) ha un livello di rumore accettabile; 11) ha funzione riproducibile; 12) mantiene la sua funzionalità per una vita ragionevole, coerente con la sua classe generica; 13) mantiene la sua funzionalità e la sterilità di una mensola ragionevole vita prima dell&#39;impianto. &quot;11. Alcuni dei difetti delle protesi valvolari esistenti possono potenzialmente essere superato da una valvola di polimero. polimeri biocompatibili sono stati considerati migliori candidati sulla base biostabilità, anti-idrolisi, anti-ossidazione, e le proprietà meccaniche vantaggiose come ad alta resistenza e viscoelasticità., in particolare, i polimeri elastomerici possono prevedere la deformazione del materiale simile dinamica della valvola nativa. elastomeri può essere adattato per simulare le proprietà dei tessuti molli, e possono essere i soli materiali artificiali disponibili che sono bio-tollerante e in grado di sopportare l&#39;accoppiata, in vivo, fluido sollecitazioni indotte, flessione e trazione, tuttavia, si muovono in maniera simile sano,movimento della valvola nativa. Inoltre, elastomeri può essere prodotto in una varietà di formati, archiviati con facilità, si pensa che sia i dispositivi di costo-efficacia e può essere strutturalmente aumentata con rinforzo fibroso. Il concetto di uso di materiali polimerici per assemblare una valvola tri-foglio non è nuova ed è stata oggetto di numerose ricerche cliniche negli ultimi 50 anni 12, che sono stati abbandonati gran parte dovuto durevolezza valvola limitata. Tuttavia, con l&#39;avvento di nuove metodologie di produzione 13,14, il rinforzo di materiali polimerici 15,16 e l&#39;integrazione senza soluzione di polimero potenzialmente sostituti valvole e con tecnologia valvola transcatetere, vi è stato recentemente un rinnovato interesse e di attività per lo sviluppo di valvole di polimeri come potenzialmente valida alternativa alle valvole commerciali attualmente disponibili. In questa luce, un protocollo per consentire collaudo di tali valvole per valutare la funzionalità idrodinamica è il primo passonel processo di valutazione; ancora i sistemi di simulazione di impulsi disponibili in commercio in genere non sono attrezzato per ospitare tri-opuscolo disegni valvole e contengono una spaziatura anulare di inserire valvole cardiache disponibili in commercio (ad esempio disco inclinabile, bi-leaflet valvole cardiache meccaniche). In secondo luogo, le valvole di polimero sono una tecnologia emergente il cui idrodinamica può essere valutato solo in un contesto relativo. Anche se il cuore nativo pressione valvola e dati di flusso è disponibile, è importante condurre test di valvole aortiche native suina, biologicamente simili a valvole umani, utilizzando lo stesso simulatore pulsatile che viene utilizzato per valutare le valvole polimeriche in modo da tener conto di differenze di misurazione che possono essere dipendente dal sistema. Pertanto, l&#39;obiettivo di questo studio era di dimostrare come un simulatore di impulsi disponibile in commercio può essere dotato di un gruppo di ospitare valvola tri-opuscolo costrutti e di valutare sistematicamente polimeriche valvole idrodinamiche metriche in un cont relativaext in confronto ad suina cuore controparti valvola meccanica e nativi. Nel nostro caso, nuovi tri-opuscolo valvole di polimero di silicone precedentemente sviluppato presso l&#39;Università della Florida, 13 compreso il gruppo valvola di polimero.

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Pump</td>
			<td>ViVitro Labs</td>
			<td></td>
			<td><a href="http://vivitrolabs.com/products/superpump/" target="_blank">http://vivitrolabs.com/products/superpump/</a></td>
		</tr>
		<tr>
			<td>Flow Meter and Probe</td>
			<td>Carolina Medical</td>
			<td>Model 501D</td>
			<td><a href="http://www.carolinamedicalelectronics.com/documents/FM501.pdf" target="_blank">http://www.carolinamedicalelectronics.com/documents/FM501.pdf</a></td>
		</tr>
		<tr>
			<td>Pressure Transducer</td>
			<td>ViVitro Labs</td>
			<td>HCM018</td>
			<td></td>
		</tr>
		<tr>
			<td>ViVitro Pressure Measuring Assembly</td>
			<td>ViVitro Labs</td>
			<td>6186</td>
			<td></td>
		</tr>
		<tr>
			<td>Valve holder</td>
			<td>WB Engineering</td>
			<td></td>
			<td>Designed by Florida International University. Manufactured by WB Engineering</td>
		</tr>
		<tr>
			<td>Pulse Duplicator</td>
			<td>ViVitro Labs</td>
			<td>PD2010</td>
			<td><a href="http://vivitrolabs.com/wp-content/uploads/Pulse-Duplicator-Accessories1.pdf" target="_blank">http://vivitrolabs.com/wp-content/uploads/Pulse-Duplicator-Accessories1.pdf</a></td>
		</tr>
		<tr>
			<td>Pulse Duplicator Data Acquisition and Control System, including ViViTest Software</td>
			<td>ViVitro Labs</td>
			<td>PDA2010</td>
			<td><a href="http://vivitrolabs.com/products/software-daq" target="_blank">http://vivitrolabs.com/products/software-daq</a></td>
		</tr>
		<tr>
			<td>Porcine Hearts and Native Aortic Valves</td>
			<td>Mary&#39;s Ranch Inc</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bi-leaflet Mechanical Valves</td>
			<td>Saint Jude Medical</td>
			<td></td>
			<td><a href="http://www.sjm.com/" target="_blank">http://www.sjm.com/</a></td>
		</tr>
		<tr>
			<td>High Vacuum Grease</td>
			<td>Dow Corning Corporation</td>
			<td></td>
			<td><a href="http://www1.dowcorning.com/DataFiles/090007b281afed0e.pdf" target="_blank">http://www1.dowcorning.com/DataFiles/090007b281afed0e.pdf</a></td>
		</tr>
		<tr>
			<td>Glycerin</td>
			<td>McMaster-Carr</td>
			<td>3190K293</td>
			<td>99% Natural 5 gal</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>Fisher Scientific</td>
			<td>MT21031CV</td>
			<td>100 ml/heart</td>
		</tr>
		<tr>
			<td>Antimycotic/Antibiotic Solution</td>
			<td>Fisher Scientific</td>
			<td>SV3007901</td>
			<td>1 ml in 100 ml of PBS/heart; 20 ml for ViVitro System</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>S3014-500G</td>
			<td>9 g/L of deionized water</td>
		</tr>
		<tr>
			<td>Deionized Water</td>
			<td>EMD Millipore Chemicals</td>
			<td></td>
			<td>Millipore Deionized Purification System. 1.3 L for ViVitro System, 200 ml for heart valve dissection process</td>
		</tr>
	</tbody>
</table>

protocol for relative hydrodynamic assessment of tri-leaflet polymer valves

Limitazioni di valvole attualmente disponibili protesici, xenotrapianti, e homograft hanno indotto una recente recrudescenza degli sviluppi in materia di tri-opuscolo polimero protesi valvolari. Comunque, l&#39;individuazione di un protocollo per la valutazione iniziale della funzionalità idrodinamica valvola polimero è fondamentale durante le prime fasi del processo di progettazione. Tradizionale nei sistemi di duplicatori di impulso in vitro non sono configurati per ospitare materiali tri-opuscolo flessibili, inoltre, la valutazione della funzionalità della valvola polimero deve essere fatta in un contesto relativo alle valvole cardiache native e protesiche in condizioni di prova identiche in modo che la variabilità nelle misurazioni da diverso strumenti possono essere evitati. Pertanto, abbiamo condotto valutazione idrodinamico di i) nativa (n = 4, diametro medio, D = 20 mm), ii) bi-pieghevole meccanico (n = 2, D = 23 mm) e iii) le valvole polimero (n = 5, D = 22 mm) tramite l&#39;uso di un sistema di duplicazione impulso disponibile in commercio (ViVitro LabsInc, Victoria, BC), che è stato modificato per ospitare valvola tri-opuscolo geometrie. Valvole di silicone Tri-volantino sviluppati presso l&#39;Università della Florida, compreso il gruppo di valvola di polimero. Una miscela in rapporto di glicerina 35:65 all&#39;acqua è stato usato per mimare le proprietà fisiche del sangue. Portata istantanea è stata misurata in corrispondenza dell&#39;interfaccia del ventricolo sinistro e dell&#39;aorta unità mentre la pressione è stata registrata nelle posizioni ventricolari e aortica. Bi-volantino e dati della valvola nativa della letteratura è stato utilizzato per convalidare il flusso e pressione. Sono stati riportati i seguenti parametri idrodinamici: avanti la caduta di pressione del flusso, della radice aortica significa tasso quadrato in avanti di portata, chiusura aortica, di dispersione e di volume di rigurgito, chiusura transaortico, le perdite e le perdite di energia totale. Rappresentante risultati hanno indicato che i parametri idrodinamici dei tre gruppi di valvole potrebbero essere ottenuti con successo, incorporando un assemblaggio su misura in un sistema di duplicazione di impulsi disponibili in commercio e subsequently, oggettivamente rispetto di fornire approfondimenti su aspetti funzionali del polimero di disegno della valvola.

Flusso rappresentativo e forme d&#39;onda di pressione sono mostrate nelle figure 3, 4 e 5. Le trame sono state una media di oltre la dimensione del campione di valvole testate per ogni gruppo, che è stato, n = 5, 4, e 2 valvole per polimero, suini nativa e gruppi bi-volantino, rispettivamente. Le metriche idrodinamico e l&#39;errore standard della media di queste dimensioni del campione sono presentati nella tabella 1. <p class="jove_content" fo:keep-together.with...

Watch this Scientific Journal Video about Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves at JoVE.com

Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

C&#39;è stato un rinnovato interesse per lo sviluppo di valvole polimeriche. Qui, gli obiettivi sono a dimostrare la fattibilità della modifica di un duplicatore di impulso commerciale per accogliere geometrie tri-opuscolo e di definire un protocollo per presentare polimeriche dati idrodinamici delle valvole rispetto ai dati della valvola nativa e protesica raccolti in condizioni quasi identiche.

Protocollo per la relativa valutazione idrodinamica del Tri-volantino Polymer Valvole

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

protocol-for-relative-hydrodynamic-assessment-tri-leaflet-polymer

Research

JoVE Journal

Bioengineering

13.7K Views.  Florida International University. C'è stato un rinnovato interesse per lo sviluppo di valvole polimeriche. Qui, gli obiettivi sono a dimostrare la fattibilità della modifica di un duplicatore di impulso commerciale per accogliere geometrie tri-opuscolo e di definire un protocollo per presentare polimeriche dati idrodinamici delle valvole rispetto ai dati della valvola nativa e protesica raccolti in condizioni quasi identiche.

Video: Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

A Microfluidic-based Hydrodynamic Trap for Single Particles

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science. Methods for particle trapping based on optical, magnetic, electrokinetic, and acoustic techniques have led to major advancements in physics and biology ranging from the molecular to cellular level. In this article, we introduce a new microfluidic-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method, we demonstrate trapping of micro- and nano-scale particles in aqueous solutions for long time scales. The hydrodynamic trap consists of an integrated microfluidic device with a cross-slot channel geometry where two opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation point (zero-velocity point). In this device, particles are confined at the trap center by active control of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles are effectively trapped in free solution using a feedback control algorithm implemented with a custom-built LabVIEW code. The control algorithm consists of image acquisition for a particle in the microfluidic device, followed by particle tracking, determination of particle centroid position, and active adjustment of fluid flow by regulating the pressure applied to an on-chip pneumatic valve using a pressure regulator. In this way, the on-chip dynamic metering valve functions to regulate the relative flow rates in the outlet channels, thereby enabling fine-scale control of stagnation point position and particle trapping. The microfluidic-based hydrodynamic trap exhibits several advantages as a method for particle trapping. Hydrodynamic trapping is possible for any arbitrary particle without specific requirements on the physical or chemical properties of the trapped object. In addition, hydrodynamic trapping enables confinement of a "single" target object in concentrated or crowded particle suspensions, which is difficult using alternative force field-based trapping methods. The hydrodynamic trap is user-friendly, straightforward to implement and may be added to existing microfluidic devices to facilitate trapping and long-time analysis of particles. Overall, the hydrodynamic trap is a new platform for confinement, micromanipulation, and observation of particles without surface immobilization and eliminates the need for potentially perturbative optical, magnetic, and electric fields in the free-solution trapping of small particles.

In this article, we present a microfluidic-based method for particle confinement based on hydrodynamic flow. We demonstrate stable particle trapping at a fluid stagnation point using a feedback control mechanism, thereby enabling confinement and micromanipulation of arbitrary particles in an integrated microdevice.

Un Microfluidic basato Trappola idrodinamico per particelle singole

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science.  Methods for ...

Ricerca

Bioingegneria

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

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage1-3. Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease4. 
The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve5. Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves6-9. Pulsatile bioreactors have also been developed to study a range of tissues including cartilage10, bone11 and bladder12. The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. 
The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

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

A cyclic pressure bioreactor capable of subjecting heart valve tissue to physiological and pathological pressure conditions has been designed. A LabVIEW program allows users to control pressure magnitude, amplitude and frequency. This device can be used to study the mechanobiology of heart valve tissue or isolated cells.

Progettazione di un bioreattore per la pressione ciclica Ex Vivo Studio delle valvole cardiache aortica

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic ...

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, 'SurgiLux': Preparation and Demonstration

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures can act as a nidus for infection and in many procedures are unable to effect wound repair or interfere with functional tissue regeneration.1 Surgical glues and adhesives, such as those based on fibrin and cyanoacrylates, have been developed as alternatives to sutures for the repair of such wounds. However, current commercial adhesives also have significant disadvantages, ranging from viral and prion transfer and a lack of repair strength as with the fibrin glues, to tissue toxicity and a lack of biocompatibility for the cyanoacrylate based adhesives. Furthermore, currently available surgical adhesives tend to be gel-based and can have extended curing times which limit their application.2 Similarly, the use of UV lasers to facilitate cross-linking mechanisms in protein-based or albumin 'solders' can lead to DNA damage while laser tissue welding (LTW) predisposes thermal damage to tissues.3 Despite their disadvantages, adhesives and LTW have captured approximately 30% of the wound closure market reported to be in excess of US $5 billion per annum, a significant testament to the need for sutureless technology.4
In the pursuit of sutureless technology we have utilized chitosan as a biomaterial for the development of a flexible, thin film, laser-activated surgical adhesive termed 'SurgiLux'. This novel bioadhesive uses a unique combination of biomaterials and photonics that are FDA approved and successfully used in a variety of biomedical applications and products. SurgiLux overcomes all the disadvantages associated with sutures and current surgical adhesives (see Table 1).
In this presentation we report the relatively simple protocol for the fabrication of SurgiLux and demonstrate its laser activation and tissue weld strength. SurgiLux films adhere to collagenous tissue without chemical modification such as cross-linking and through irradiation using a comparatively low-powered (120 mW) infrared laser instead of UV light. Chitosan films have a natural but weak adhesive attraction to collagen (~3 KPa), laser activation of the chitosan based SurgiLux films emphasizes the strength of this adhesion through polymer chain interactions as a consequence of transient thermal expansion.5 Without this 'activation' process, SurgiLux films are readily removed.6-9 SurgiLux has been tested both in vitro and in vivo on a variety of tissues including nerve, intestine, dura mater and cornea. In all cases it demonstrated good biocompatibility and negligible thermal damage as a consequence of irradiation.6-10

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, &#039;SurgiLux&#039;: Preparation and Demonstration

The fabrication of a novel, flexible thin film surgical adhesive from FDA approved ingredients, chitosan and indocyanine green is described. Bonding of this adhesive to collagenous tissue through a simple activation process with a low-powered infra-red laser is demonstrated.

Un Based Chitosano, Laser attivato sottile pellicola adesiva chirurgici, &#39;SURGILUX&#39;: Preparazione e dimostrazione

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures ...

Polymer Microarrays for High Throughput Discovery of Biomaterials

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format1. Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2. This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion3-5. Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction6. HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials5,3.

A description of the formation of a polymer microarray using an on-chip photopolymerization technique. The high throughput surface characterization using atomic force microscopy, water contact angle measurements, X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry and a cell attachment assay is also described.

Microarrays polimerici per Discovery High Throughput di Biomateriali

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a ...

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. 
To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.
The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

A method is discussed by which the in vivo mechanical behavior of stimuli-responsive materials is monitored as a function of time. Samples are tested ex vivo using a microtensile tester with environmental controls to simulate the physiological environment. This work further promotes understanding the in vivo behavior of our material.

Test microtrazione Environmentally-controllato di meccanica-adattivi nanocompositi polimerici per<em&gt; Ex vivo</em&gt; Caratterizzazione

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, ...

Intra-lymph Node Injection of Biodegradable Polymer Particles

Generation of adaptive immune response relies on efficient drainage or trafficking of antigen to lymph nodes for processing and presentation of these foreign molecules to T and B lymphocytes. Lymph nodes have thus become critical targets for new vaccines and immunotherapies. A recent strategy for targeting these tissues is direct lymph node injection of soluble vaccine components, and clinical trials involving this technique have been promising. Several biomaterial strategies have also been investigated to improve lymph node targeting, for example, tuning particle size for optimal drainage of biomaterial vaccine particles. In this paper we present a new method that combines direct lymph node injection with biodegradable polymer particles that can be laden with antigen, adjuvant, or other vaccine components. In this method polymeric microparticles or nanoparticles are synthesized by a modified double emulsion protocol incorporating lipid stabilizers. Particle properties (e.g.&#160;size, cargo loading) are confirmed by laser diffraction and fluorescent microscopy, respectively. Mouse lymph nodes are then identified by peripheral injection of a nontoxic tracer dye that allows visualization of the target injection site and subsequent deposition of polymer particles in lymph nodes. This technique allows direct control over the doses and combinations of biomaterials and vaccine components delivered to lymph nodes and could be harnessed in the development of new biomaterial-based vaccines.

Lymph nodes are the immunological tissues that orchestrate immune response and are a critical target for vaccines. Biomaterials have been employed to better target lymph nodes and to control delivery of antigens or adjuvants. This paper describes a technique combining these ideas to inject biocompatible polymer particles into lymph nodes.

Iniezione intra-linfonodo di particelle polimeriche biodegradabili

Generation of adaptive immune response relies on efficient drainage or trafficking of antigen to lymph nodes for processing and presentation of these ...

Manufacturing Of Robust Natural Fiber Preforms Utilizing Bacterial Cellulose as Binder

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose and short sisal fibers are dispersed into a water suspension containing bacterial cellulose. The fiber and nanocellulose suspension is then filtered (using vacuum or gravity) and the wet filter cake pressed to squeeze out any excess water, followed by a drying step. This will result in the hornification of the bacterial cellulose network, holding the loose natural fibers together.
Our method is specially suited for the manufacturing of rigid and robust preforms of hydrophilic fibers. The porous and hydrophilic nature of such fibers results in significant water uptake, drawing in the bacterial cellulose dispersed in the suspension. The bacterial cellulose will then be filtered against the surface of these fibers, forming a bacterial cellulose coating. When the loose fiber-bacterial cellulose suspension is filtered and dried, the adjacent bacterial cellulose forms a network and hornified to hold the otherwise loose fibers together.
The introduction of bacterial cellulose into the preform resulted in a significant increase of the mechanical properties of the fiber preforms. This can be attributed to the high stiffness and strength of the bacterial cellulose network. With this preform, renewable high performance hierarchical composites can also be manufactured by using conventional composite production methods, such as resin film infusion (RFI) or resin transfer molding (RTM). Here, we also describe the manufacturing of renewable hierarchical composites using double bag vacuum assisted resin infusion.

We present a novel method of manufacturing rigid and robust short natural fiber preforms using a papermaking process. Bacterial cellulose acts simultaneously as the binder for the loose fibers and provides rigidity to the fiber preforms. These preforms can be infused with a resin to produce truly green hierarchical composites.

Produzione robusta fibra naturale preforme Utilizzando batterica cellulosa come Binder

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose ...

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.

Coltura mouse cardiaca Valvole in miniatura Tissue Culture Sistema

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 ...

Film Extrusion of Crambe abyssinica/Wheat Gluten Blends

Crambe abyssinica is a plant with potential for use in industrial (non-food) plant oil production. The side stream from this oil production is a high-protein crambe meal that has limited value, as it is not fit for food or feed use. However, it contains proteins that could potentially make it a suitable raw material for higher-value products. The purpose of this study was to find methods of making this side stream into extruded films, showing that products with a higher value can be produced. The study mainly considered the development of material compositions and methods of preparing and extruding the material. Wheat gluten was added as a supportive protein matrix material, together with glycerol as a plasticizer and urea as a denaturant. The extrudate was evaluated with respect to mechanical (tensile testing) and oxygen barrier properties, and the extrudate structure was revealed visually and by scanning electron microscopy. A denser, more homogeneous material had a lower oxygen transmission rate, higher strength, and higher extensibility. The most homogeneous films were made at an extruder die temperature of 125-130 &#176;C. It is shown here that a film can be extruded with promising mechanical and oxygen barrier properties, the latter especially after a final compression molding step.

Film Extrusion of Crambe abyssinica/Wheat Gluten Blends

The side stream from plant oil production of Crambe abyssinica has limited value. The purpose of this study was to find methods for extruding materials based on this side stream, demonstrating that products with a higher value can be produced. The extrudates were found to have promising properties.

Film di Estrusione<em&gt; Abyssinica Crambe</em&gt; / Glutine di frumento Miscele

Crambe abyssinica is a plant with potential for use in industrial (non-food) plant oil production. The side stream from this oil production is a ...

Synthesis of Functionalized 10-nm Polymer-coated Gold Particles for Endothelium Targeting and Drug Delivery

Gold nanoparticles (AuNPs) have been used extensively in medical research due to their size, biocompatibility, and modifiable surface. Specific targeting and drug delivery are some of the applications of these AuNPs, but endothelial extracellular matrices&#39; defensive properties hamper particle uptake. To address this issue, we describe a synthesis method for ultrasmall gold nanoparticles to improve vascular delivery, with customizable functional groups and polymer lengths for further adjustments. The protocol yields 2.5 nm AuNPs that are capped with tetrakis(hydroxymethyl)phosphonium chloride (THPC). The replacement of THPC with hetero-functional polyethylene glycol (PEG) on the surface of the AuNP increases the hydrodynamic radius to 10.5 nm while providing various functional groups on the surface. The last part of the protocol includes an optional addition of a fluorophore to allow the AuNPs to be visualized under fluorescence to track nanoparticle uptake. Dialysis and lyophilization were used to purify and isolate the AuNPs. These fluorescent nanoparticles can be visualized in both in vitro and in vivo experiments due to the biocompatible PEG coating and fluorescent probes. Additionally, the size range of these nanoparticles render them an ideal candidate for probing the glycocalyx without disrupting normal vasculature function, which may lead to improved delivery and therapeutics.

We describe a method of synthesizing biocompatible 10-nm gold nanoparticles, functionalized by coating poly-ethylene glycol onto the surface. These particles can be used in vitro and in vivo for delivering therapeutics to nanoscale cellular and extracellular spaces that are difficult to access with conventional nanoparticle sizes.

Sintesi di particelle d'oro rivestite di polimeri 10-nm funzionalizzate per il Targeting di endotelio e Drug Delivery

Gold nanoparticles (AuNPs) have been used extensively in medical research due to their size, biocompatibility, and modifiable surface. Specific targeting ...