We would like to thank the Division of Engineering, Mayo Clinic for their technical support. This study was financially supported by European Regional Development Fund - FNUSA-ICRC (No. CZ.1.05/1.100/02.0123), National Institutes of Health (T32 HL007111), American Heart Association Scientist Development Grant (AHA #06-35185N), and The Grainger Innovation Fund - Grainger Foundation.

1. Electrospinning di poliuretano sul mandrino Collector <ol><li> Preparare mandrino per electrospinning <ol><li> Sciogliere circa 8 ml di biocompatibile, di categoria alimentare, acqua materiale di supporto solubile in un cilindro graduato (circa 9 mm di diametro e 110 mm di profondità) a 155 ° C utilizzando un forno. </li><li> Dip 3 mm di diametro ei 100 mm mandrino in acciaio inox lungo per ottenere un rivestimento di materiale di supporto sulla superficie del mandrino. Prima di immersione, posizionare i mandrini in forno a 155 ° C per circa 15 minuti per aumentare la temperatura della superficie del mandrino che aiuta a bagnare la superficie con il materiale di supporto fuso. </li><li> Sia le mandrino anabbaglianti raffreddare a circa 140 ° C mentre il materiale di supporto fuso solidifica formando un sottile rivestimento uniforme sulla superficie del mandrino. Durante il processo di raffreddamento, appendere il mandrino verticale in modo che la gravità provoca materiale di supporto in eccesso di sgocciolare. Questo rivestimento permette una facilerimozione del prodotto finito stent-graft dal mandrino. </li></ol></li><li> Impostazione del collettore mandrino del sistema elettrofilatura (come mostrato in figura 1) <ol><li> Allineare il mixer da laboratorio orizzontale e collegare una bacchetta di plastica che terrà il mandrino in acciaio inox all&#39;estremità opposta all&#39;interno della cappa. </li><li> Sciogliere il materiale di supporto dalla punta del mandrino immergendo solo la punta del mandrino in acqua per accogliere l&#39;asta di supporto plastica all&#39;estremità del mandrino. Sostenere l&#39;asta di supporto plastico in corrispondenza dell&#39;estremità libera del mandrino per aiutare nella rotazione uniforme del collettore mandrino. </li><li> Utilizzare viti nelle aste di supporto in plastica per fissare il mandrino in acciaio inox e evitare di scivolare durante electrospinning. </li><li> A terra il collettore mandrino collegando un filo di terra a forma di U al mandrino in acciaio inossidabile. Utilizzare O-ring di gomma per tenere il filo di terra ai lati del mandrino. </li></ol></li><li> Setting liquido sistema di estrusione poliuretano del sistema electrospinning <ol><li> Mescolare dimetilacetammide (DMA) con il 25% (m / v) di poliuretano (PU) stock soluzione per ottenere 15% (m / v) PU in DMA soluzione (ad esempio, aggiungere 6 ml di DMA a soluzione PU 9 ml di 25%). ATTENZIONE! Lavorare all&#39;interno di una cappa aspirante con un equipaggiamento di protezione individuale. </li><li> Riempire una siringa di vetro da 5 ml con estremità smussata ago in acciaio inox (filiera) con una soluzione di PU 15%. </li><li> Programmare la pompa a siringa da estrudere a 0.01 ml / min in base al diametro interno della siringa. </li><li> Montare la siringa con filiera sulla pompa a siringa orizzontalmente con la punta dell&#39;ago circa 20 cm dal collettore mandrino. Isolare la siringa dalle parti conduttrici della siringa pompa utilizzando fogli di gomma per evitare formazione di archi elettrici. </li><li> Collegare il generatore ad alta tensione per la filiera della siringa con un coccodrillo. </li></ol></li><li> Eseguire la pompa a siringa a 0.01 ml / min e RotaTE il mandrino con il mixer da laboratorio funziona a bassa velocità (ad esempio, 50 giri). </li><li> Applicare un differenziale di tensione di 20 kV attraverso la filiera e il mandrino collettore. nanofibre PU inizieranno depositando sul mandrino rotante e un sottile strato saranno visibili in pochi minuti. Assicurarsi che la cappa è spento e lo scarico è chiusa per evitare la perdita di nanofibre elettrofilate. </li></ol> 2. Electrospinning uno stent-graft <ol><li> nanofibre Electrospin PU su un mandrino rotante per 2 ore per creare un tubo uniforme (come spiegato nel passaggio 1). </li><li> Rimuovere il mandrino dalla bacchetta di plastica collegato al mixer laboratorio per installare il stent di metallo nudo. Accendere cappa e scarico aperto prima di rimuovere il mandrino per garantire che resti vapori di solvente vengono rimossi. </li><li> Far scorrere il pallone stent in acciaio inox espandibile 26 sul tubo elettrofilate nella posizione desiderata. Può essere necessario espandersi leggermente lo stent così Slips avanti senza danneggiare il tubo elettrofilate. </li><li> Crimpare lo stent per assicurarsi che lo stent sia saldamente fissato sul materiale del tubo sul mandrino e non abbastanza largo da scorrere. Questo aiuterà anche a prevenire la delaminazione degli strati interni ed esterni. </li><li> Caricare il mandrino con il tubo e stent nuovo sull&#39;asta di plastica del miscelatore laboratorio per electrospinning lo strato esterno dello stent-graft. </li><li> nanofibre Electrospin per 3 ore come spiegato nel passaggio 1 per fabbricare lo strato esterno dello stent-graft. </li><li> Dopo electrospinning l&#39;esterno dopo, circonferenzialmente tagliare il materiale PU circa 1 mm dalla estremità dello stent utilizzando un bisturi. </li><li> Bagnare il mandrino con stent-graft in acqua deionizzata per sciogliere il materiale di supporto dal mandrino che rilascerà lo stent-graft da mandrino. Sostituire con acqua dolce come necessario per sciogliere completamente il materiale di supporto. </li><li> Una volta che il materiale di supporto è sciolto, rimuovere delicatamente lo stent-graft da tegli mandrino e lasciare asciugare. Considerate ammollo lo stent-graft rimosso in acqua deionizzata per sciogliere qualsiasi materiale di supporto rimanente prima di consentire asciugare all&#39;aria. </li></ol> 3. Test di fabbricati stent innesti <ol><li> Far scorrere lo stent-graft su un pallone a tre ante 3 mm. </li><li> Crimp lo stent-graft sul pallone con una mano tesa pinza. </li><li> Ispezionare lo stent-graft pressare utilizzando un microscopio per aggraffatura uniforme e qualsiasi altro segno di fallimento come la delaminazione o la puntura del materiale di copertura a causa della deformazione dello stent. </li><li> Espandere lo stent-graft al diametro progettato di 3 mm dalla pressurizzazione del pallone a tre ante con un dispositivo di gonfiaggio e acqua. Anche in questo caso, esaminare lo stent-graft ampliato per l&#39;espansione uniforme e segni di insufficienza. </li></ol>

<ol>
	<li>Elsner, 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=Coronary+stent+grafts+covered+by+a+polytetrafluoroethylene+membrane.">Coronary stent grafts covered by a polytetrafluoroethylene membrane.</a> Am. J. Cardiol. 84 (3), 335-338 (1999).</li><li>St&#246;rger, H., Haase, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polytetrafluoroethylene-Covered+Stents:+Indications,+Advantages,+and+Limitations.">Polytetrafluoroethylene-Covered Stents: Indications, Advantages, and Limitations.</a> J. Interv. Cardiol. 12 (6), 451-456 (1999).</li><li>Moreno, P. 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=Macrophage+infiltration+predicts+restenosis+after+coronary+intervention+in+patients+with+unstable+angina.">Macrophage infiltration predicts restenosis after coronary intervention in patients with unstable angina.</a> Circulation. 94 (12), 3098-3102 (1996).</li><li>Briguori, C., Sarais, C., Colombo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+polytetrafluoroethylene-covered+stent:+a+device+with+multiple+potential+advantages.">The polytetrafluoroethylene-covered stent: a device with multiple potential advantages.</a> Int. J. Cardiovasc. Interv. 4 (3), 145-149 (2001).</li><li>Qureshi, M. A., Martin, Z., Greenberg, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endovascular+management+of+patients+with+Takayasu+arteritis:+stents+versus+stent+grafts.">Endovascular management of patients with Takayasu arteritis: stents versus stent grafts.</a> Semin. Vasc. Surg. 24 (1), 44-52 (2011).</li><li>Ahmadi, R., Schillinger, M., Maca, T., Minar, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femoropopliteal+arteries:+immediate+and+long-term+results+with+a+Dacron-covered+stent-graft.">Femoropopliteal arteries: immediate and long-term results with a Dacron-covered stent-graft.</a> Radiology. 223 (2), 345-350 (2002).</li><li>Geremia, G., 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=Experimental+arteriovenous+fistulas:+treatment+with+silicone-covered+metallic+stents.">Experimental arteriovenous fistulas: treatment with silicone-covered metallic stents.</a> AJNR. Am. J. Neuroradiol. 18 (2), 271-277 (1997).</li><li>Saatci, I., 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=Treatment+of+internal+carotid+artery+aneurysms+with+a+covered+stent:+experience+in+24+patients+with+mid-term+follow-up+results.">Treatment of internal carotid artery aneurysms with a covered stent: experience in 24 patients with mid-term follow-up results.</a> AJNR. Am. J. Neuroradiol. 25 (10), 1742-1749 (2004).</li><li>Stefanadis, C., 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=Stents+Wrapped+in+Autologous+Vein:+An+Experimental+Study1.">Stents Wrapped in Autologous Vein: An Experimental Study1.</a> J. Am. Coll. Cardiol. 28 (4), 1039-1046 (1996).</li><li>Palmaz, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Review+of+polymeric+graft+materials+for+endovascular+applications.">Review of polymeric graft materials for endovascular applications.</a> J. Vasc. Interv. Radiol. 9, 7-13 (1998).</li><li>Bruckheimer, E., Dagan, T., Amir, G., Birk, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Covered+Cheatham-Platinum+stents+for+serial+dilation+of+severe+native+aortic+coarctation.">Covered Cheatham-Platinum stents for serial dilation of severe native aortic coarctation.</a> Catheter Cardiovasc. Interv. 74 (1), 117-123 (2009).</li><li>Tzifa, A., 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=Covered+Cheatham-platinum+stents+for+aortic+coarctation:+early+and+intermediate-term+results.">Covered Cheatham-platinum stents for aortic coarctation: early and intermediate-term results.</a> J. Am. Coll. Cardiol. 47 (7), 1457-1463 (2006).</li><li>Kuraishi, K., 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=Development+of+nanofiber-covered+stents+using+electrospinning:+in+vitro+and+acute+phase+in+vivo+experiments.">Development of nanofiber-covered stents using electrospinning: in vitro and acute phase in vivo experiments.</a> J. Biomed. Mater. Res. Part B Appl. Biomater. 88 (1), 230-239 (2009).</li><li>Pant, S., Bressloff, N. W., Limbert, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Geometry+parameterization+and+multidisciplinary+constrained+optimization+of+coronary+stents.">Geometry parameterization and multidisciplinary constrained optimization of coronary stents.</a> Biomech. Model Mechanobiol. 11 (1-2), 61-82 (2012).</li><li>Muller-Hulsbeck, 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=Experience+on+endothelial+cell+adhesion+on+vascular+stents+and+stent-grafts:+first+in+vitro+results.">Experience on endothelial cell adhesion on vascular stents and stent-grafts: first in vitro results.</a> Invest. Radiol. 37 (6), 314-320 (2002).</li><li>Sarkar, S., Salacinski, H. J., Hamilton, G., Seifalian, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mechanical+properties+of+infrainguinal+vascular+bypass+grafts:+their+role+in+influencing+patency.">The mechanical properties of infrainguinal vascular bypass grafts: their role in influencing patency.</a> Eur. J. Vasc. Endovasc. Surg. 31 (6), 627-636 (2006).</li><li>Shirota, T., Yasui, H., Shimokawa, H., Matsuda, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+endothelial+progenitor+cell+(EPC)-seeded+intravascular+stent+devices+and+in+vitro+endothelialization+on+hybrid+vascular+tissue.">Fabrication of endothelial progenitor cell (EPC)-seeded intravascular stent devices and in vitro endothelialization on hybrid vascular tissue.</a> Biomaterials. 24 (13), 2295-2302 (2003).</li><li>Grasl, C., 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=Electrospun+polyurethane+vascular+grafts:+in+vitro+mechanical+behavior+and+endothelial+adhesion+molecule+expression.">Electrospun polyurethane vascular grafts: in vitro mechanical behavior and endothelial adhesion molecule expression.</a> J. Biomed. Mater. Res. A. 93 (2), 716-723 (2010).</li><li>Kidoaki, S., Kwon, I. K., Matsuda, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+features+and+mechanical+properties+of+in+situ-bonded+meshes+of+segmented+polyurethane+electrospun+from+mixed+solvents.">Structural features and mechanical properties of in situ-bonded meshes of segmented polyurethane electrospun from mixed solvents.</a> J. Biomed. Mater. Res. Part B Appl. Biomater. 76 (1), 219-229 (2006).</li><li>Stegemann, J. P., Kaszuba, S. N., Rowe, 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=Review:+advances+in+vascular+tissue+engineering+using+protein-based+biomaterials.">Review: advances in vascular tissue engineering using protein-based biomaterials.</a> Tissue Eng. 13 (11), 2601-2613 (2007).</li><li>Sankaran, K. K., Subramanian, A., Krishnan, U. M., Sethuraman, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoarchitecture+of+scaffolds+and+endothelial+cells+in+engineering+small+diameter+vascular+grafts.">Nanoarchitecture of scaffolds and endothelial cells in engineering small diameter vascular grafts.</a> Biotechnol. J. 10 (1), 96-108 (2015).</li><li>Gibson, P., Schreuder-Gibson, H., Rivin, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transport+properties+of+porous+membranes+based+on+electrospun+nanofibers.">Transport properties of porous membranes based on electrospun nanofibers.</a> Colloid Surf., A. 187, 469-481 (2001).</li><li>Zdrahala, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+caliber+vascular+grafts.+Part+II:+Polyurethanes+revisited.">Small caliber vascular grafts. Part II: Polyurethanes revisited.</a> J. Biomater. Appl. 11 (1), 37-61 (1996).</li><li>Uthamaraj, 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=Design+and+validation+of+a+novel+ferromagnetic+bare+metal+stent+capable+of+capturing+and+retaining+endothelial+cells.">Design and validation of a novel ferromagnetic bare metal stent capable of capturing and retaining endothelial cells.</a> Ann. Biomed. Eng. 42 (12), 2416-2424 (2014).</li><li>Tefft, B. J., 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=Cell+Labeling+and+Targeting+with+Superparamagnetic+Iron+Oxide+Nanoparticles.">Cell Labeling and Targeting with Superparamagnetic Iron Oxide Nanoparticles.</a> J. Vis. Exp. (105), e53099 (2015).</li><li>Uthamaraj, 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=Ferromagnetic+Bare+Metal+Stent+for+Endothelial+Cell+Capture+and+Retention.">Ferromagnetic Bare Metal Stent for Endothelial Cell Capture and Retention.</a> J. Vis. Exp. (103), e53100 (2015).</li><li>de Giovanni, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Covered+stents+in+the+treatment+of+aortic+coarctation.">Covered stents in the treatment of aortic coarctation.</a> J. Interv. Cardiol. 14 (2), 187-190 (2001).</li><li>Hans, F. J., 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=Treatment+of+wide-necked+aneurysms+with+balloon-expandable+polyurethane-covered+stentgrafts:+experience+in+an+animal+model.">Treatment of wide-necked aneurysms with balloon-expandable polyurethane-covered stentgrafts: experience in an animal model.</a> Acta. Neurochir. (Wien). 147 (8), 871-876 (2005).</li><li>Hasan, A., 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=Electrospun+scaffolds+for+tissue+engineering+of+vascular+grafts.">Electrospun scaffolds for tissue engineering of vascular grafts.</a> Acta. Biomater. 10 (1), 11-25 (2014).</li></ol>

Gli autori dichiarano di non avere interessi finanziari concorrenti.

We have developed a fabrication technique for a small caliber stent-graft which can be deployed using a standard percutaneous coronary intervention (PCI) procedure. Stent-grafts currently available are limited in their ability to maintain a low profile and flexibility for deployment. Bare metal stents developed by our group in our previous studies have proven to assist in rapid healing of the stented artery24,26. Various polymers have been electrospun by other groups and polyurethane has been proven biostable and biocompatible. Polyurethane is also known to have very little bacterial adherence13,28. 
In the protocol presented in this study, we have developed a stent-graft with a balloon-expandable stent sandwiched between two layers of electrospun polyurethane and furthermore tested these stent-grafts for crimping and expansion. First, we have developed a stainless steel stent which is capable of crimping and expanding using standard PCI techniques. Second, we have developed an electrospinning technique which can generate good quality polyurethane nanofibers on a rotating mandrel collector. Finally, we have developed a process to sandwich the stent between two electrospun PU layers without delamination. The final device is capable of crimping and expansion on a standard 3 mm trifold balloon. We implanted 1-2 of these stent-grafts into 12 pigs (n=22 stent-grafts total) using standard 8 or 9 French guide catheters. The stent-grafts explanted after 7 days of implantation did not show any signs of mechanical failure nor occlusion of the blood vessel.
Stent-grafts are limited in use to large and medium caliber vessels and cannot be used in coronary vessels. Development of small caliber stent-grafts has been limited by the ability to control the thickness of the material covering the stent. Electrospinning of polyurethane provides the ability to precisely control the thickness of the material. The thickness of the electrospun polyurethane layer is time-dependent and the rate of accumulation is mainly affected by the distance between the spinneret and the collector mandrel, PU to DMA ratio, and the diameter of the collector mandrel. It should be noted that the length of a stent-graft presented in this protocol is 15 mm while the distance of the spinneret from the collecting mandrel is 200 mm. Hence, the ratio of stent-graft length to the distance is less than 0.1 which results in uniform electrospun nanofibrous layers. We used 15% (m/v) PU in DMA to obtain the desired uniform electrospun layers with high quality nanofibers. In the approach presented here, electrospun polyurethane nanofibers were deposited at the rate of 50 &#181;m/hr on the rotating mandrel collector. The thickness of the inner layer was 100 &#181;m while the thickness of the outer layer was 150 &#181;m. Thicker nanofibrous material results in stiffer stent-grafts with a larger crimp profile, while thinner material results in puncturing during crimping and expansion. The resulting stent-grafts are prone to delamination, but this can be mitigated by crimping the stent on the inner layer prior to electrospinning the outer layer. It is also important to cut the electrospun material carefully, because cutting too close to the ends of the stent will cause the two layers to delaminate at the ends. Another critical step to achieve good quality stent-grafts is to uniformly coat the mandrel with water soluble, biocompatible support material. This helps in removing the stent-graft from the mandrel without disrupting the inner layer. This also helps to achieve a smooth inner surface of the stent-grafts.
Electrospun nanofibrous polyurethane covered stent-grafts are currently being used for treatment of aneurysms13. These stent-grafts are manufactured by sandwiching electrospun material between two stents which results in limited flexibility of the stent-grafts. The stent-graft developed in our study by sandwiching a balloon expandable stent between two electrospun layers has the advantage of using the flexibility of one stent while using the advantages of nanofibers for healing and mechanical strength. Nanofibrous material has the advantage of mimicking natural extracellular matrix which assists in healing of vascular grafts29. Stent-grafts developed in this study by combining electrospinning and balloon expandable stents have the potential to help in further development of rapidly healing small caliber stent-grafts.

procedure di intervento coronarico causano significative lesioni parete del vaso a causa di rottura della placca e la parete del serbatoio. Ciò si traduce in restenosi, embolia periferica in innesti di vena, e la discontinuità del lume coronarico 1-4. Per evitare queste complicazioni, una strategia promettente sarà da coprire la superficie vascolare nel sito angioplastica, che potenzialmente inibire la ristenosi, ridurre i rischi di discontinuità del lume del vaso, e prevenire embolia periferica. Precedenti studi hanno confrontato gli stent di metallo nudo di stent innesti con risultati positivi per stent-graft 5. I ricercatori hanno utilizzato diversi materiali per la fabbricazione di membrane per coprire gli stent. Questo include materiali sintetici come polietilene tetraphthalate (PET), politetrafluoroetilene (PTFE), poliuretano (PU), e silicio o tessuto del vaso autologo per fabbricare coperte stent 6-9. Un materiale di innesto ideale utilizzato per coprire lo stent dovrebbe essere thromboresistant, non biodegradable, e dovrebbe integrarsi con il tessuto nativo senza eccessiva proliferazione e l&#39;infiammazione 10. Il materiale di innesto utilizzato per coprire lo stent dovrebbe anche promuovere la guarigione dello stent-graft. Stent innesti sono ampiamente utilizzati per il trattamento di coartazione aortica, pseudo-aneurismi dell&#39;arteria carotidea, fistola artero-venosa, degenerati vena innesti, e grande per giganti aneurismi cerebrali. Ma lo sviluppo di piccole calibro stent-innesti è limitata dalla capacità di mantenere basso profilo e flessibilità, che aiuta nella distribuzione degli stent-innesti 11-14. PU è un polimero elastomerico con una buona resistenza meccanica, che è una caratteristica desiderata per realizzare un profilo basso e buona flessibilità 15,16. Oltre ad avere una buona deliverability, stent-innesti dovrebbero anche promuovere una rapida guarigione e endotelizzazione. PU coperto stent-innesti hanno dimostrato una migliore biocompatibilità e endotelizzazione 17 migliorata. I ricercatori hannoin precedenza cercato di endothelialize PU coperto stent-graft da loro semina con le cellule endoteliali 17. Electrospinning di PU per creare matrice nanofibre ha dimostrato di essere una tecnica utile per la produzione di innesti vascolari 18,19. L&#39;esistenza di nanofibre che imitano l&#39;architettura della matrice extracellulare nativa è noto anche per promuovere la proliferazione delle cellule endoteliali 20,21. Electrospinning consente anche di controllo dello spessore del materiale 22. Piccolo calibro innesti vascolari in PU sono state studiate per promuovere la guarigione mediante modifiche come rivestimenti superficiali, anticoagulanti, e soppressori di proliferazione cellulare. Tutte queste modifiche sono progettate per mediare l&#39;accettazione di accoglienza e promuovere la guarigione dell&#39;innesto 23. Il nostro gruppo ha sviluppato un palloncino espandibile stent di metallo nudo che può essere implementato in modelli animali 24-26. La combinazione di una maglia elettrofilate poliuretano e una pallaoon stent espandibili ci ha permesso di generare piccolo calibro palloncino espandibile stent-innesti. La maggior parte degli stent-innesti attualmente disponibili sono introdotte attraverso l&#39;arteria femorale durante una procedura interventistica, ma solo pochi stents rivestiti commerciali può essere introdotto 1 formato French grande di quello richiesto per un palloncino gonfiato un-27. In questo studio abbiamo sviluppato un piccolo calibro vascolare stent-graft incapsulando uno stent espandibile a palloncino tra due strati di elettrofilate PU che possono essere consegnati a una arteria coronaria utilizzando uno standard 8-9 francese guida catetere in una procedura interventistica percutanea.

<table border="0" cellpadding="0" cellspacing="0" width="986">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Glass syringe</td>
			<td style="width:155px;">Air Tite</td>
			<td style="width:135px;">7.140-33</td>
			<td style="width:457px;">Syringe for spinneret</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Graduated cylinder 5 mL</td>
			<td style="width:155px;">Fisher Scientific</td>
			<td style="width:135px;">08-552-4G</td>
			<td>5 mL pyrex graduated cylinder about 9mm diameter and 11 cm long</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:240px;">High voltage generator</td>
			<td style="width:155px;">Bertan Accociates, Inc.</td>
			<td style="width:135px;">205A-30P</td>
			<td>Used to apply voltage difference across spinneret and collector</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Laboratory mixer with rpm control</td>
			<td style="width:155px;">Scilogex</td>
			<td style="width:135px;">SCI-84010201</td>
			<td>Available from various laboratory equipment suppliers</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Polyurethane</td>
			<td style="width:155px;">DSM</td>
			<td style="width:135px;">BioSpan SPU</td>
			<td>Biospan Segmented Polyurethane</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Rubber sheet</td>
			<td style="width:155px;">McMaster Carr</td>
			<td style="width:135px;">1370N11</td>
			<td>Used to insulate syringe during electrospinning</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Stainless steel mandrel</td>
			<td style="width:155px;">N/A</td>
			<td style="width:135px;">N/A</td>
			<td>Manufactured&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Stainless steel needle</td>
			<td style="width:155px;">Hamilton</td>
			<td style="width:135px;">91018</td>
			<td>Used as spinneret in electrospinning</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Support material</td>
			<td style="width:155px;">EnvisionTec</td>
			<td style="width:135px;">B04-HT-DEMOMAT</td>
			<td>Biocompatible water soluble material</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:240px;">Syringe Pump</td>
			<td style="width:155px;">Harvard Apparatus</td>
			<td style="width:135px;">55-3333</td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication of small caliber stent-grafts using electrospinning and balloon expandable bare metal stents

Stent-grafts are widely used for the treatment of various conditions such as aortic lesions, aneurysms, emboli due to coronary intervention procedures and perforations in vasculature. Such stent-grafts are manufactured by covering a stent with a polymer membrane. An ideal stent-graft should have a biocompatible stent covered by a porous, thromboresistant, and biocompatible polymer membrane which mimics the extracellular matrix thereby promoting injury site healing. The goal of this protocol is to manufacture a small caliber stent-graft by encapsulating a balloon expandable stent within two layers of electrospun polyurethane nanofibers. Electrospinning of polyurethane has been shown to assist in healing by mimicking native extracellular matrix, thereby promoting endothelialization. Electrospinning polyurethane nanofibers on a slowly rotating mandrel enabled us to precisely control the thickness of the nanofibrous membrane, which is essential to achieve a small caliber balloon expandable stent-graft. Mechanical validation by crimping and expansion of the stent-graft has shown that the nanofibrous polyurethane membrane is sufficiently flexible to crimp and expand while staying patent without showing any signs of tearing or delamination. Furthermore, stent-grafts fabricated using the methods described here are capable of being implanted using a coronary intervention procedure using standard size guide catheters.

<html> La nostra messa a punto electrospinner (figura 1) ha portato a nanofibre poliuretano di alta qualità (Figura 2). Uno stent-graft è prodotto da elettrospinning uno strato interno di poliuretano su un mandrino, scivolando uno stent di metallo nudo sopra questo strato, e electrospinning un secondo strato esterno di poliuretano (figura 3). nanofibre poliuretaniche sono elettrofilate alla velocità di 50 um / hr, che si traduce in uno strato interno di 100 um e uno strato esterno di 150 micron sullo stent-innesti. Electrospinning utilizzando il protocollo qui presentata si traduce in strati nanofibrous poliuretano uniformi (Figura 4). Di piegatura e l&#39;espansione della risultante di piccolo calibro dello stent-graft ha dimostrato che questi dispositivi sono in grado di essere implementato usando un palloncino a tre ante standard senza aggraffatura irregolare né segni di insufficienza materiale (Figura 5). <html> ure 1 &quot;src =&quot; / files / ftp_upload / 54731 / 54731fig1.jpg &quot;/&gt; Figura 1. Schema di electrospinning procedura. Le nanofibre prodotte dalla filiera vengono raccolti su un mandrino rotante. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54731/54731fig1large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> <img alt="figura 2" src="/files/ftp_upload/54731/54731fig2.jpg" /> Figura 2. microscopia elettronica a scansione (SEM) immagini di nanofibre in poliuretano. Immagini SEM di materiale poliuretanico nanofibrous mostra orientata in modo casuale nanofibre in (A) di ingrandimento 5,000X e (b) 10.000X ingrandimento. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54731/54731fig2large.jpg" target="_blank">Cliccate qui per vedere una versione più grande di questa figura .</a> IGURA 3 &quot;src =&quot; / files / ftp_upload / 54731 / 54731fig3.jpg &quot;/&gt; Figura 3. Procedimento per la fabbricazione di stent-innesti. (A) elettrofilate strato interno di stent-graft, (b) palloncino stent espandibile caricato sullo strato elettrofilate, (c) strato esterno elettrofilate di stent-graft, (d) stent-graft tagliare a misura sul mandrino, e (e) stent-graft con strati interno ed esterno a strati nanofibrous PU. Ogni divisione sulla scala rappresenta 0,5 mm. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54731/54731fig3large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 4" src="/files/ftp_upload/54731/54731fig4.jpg" /> Figura 4. immagini Microscopia di strati di poliuretano elettrofilate su un mandrino in acciaio inox. (A) mandrino senza strato nanofibrous, (b </strong<html> &gt;) Strato di poliuretano nanofibrous sul mandrino dopo 2 ore di electrospinning, e (strato di poliuretano c) nanofibrous sul mandrino dopo 5 ore di electrospinning. Ispezione di strati di poliuretano mostra spessore uniforme lungo il mandrino in diversi momenti della electrospinning. Ogni divisione sulla scala rappresenta 0,5 mm. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54731/54731fig4large.jpg" target="_blank">Clicca qui per vedere una versione più grande di questa figura.</a> <img alt="Figura 5" src="/files/ftp_upload/54731/54731fig5.jpg" /> Figura 5. Prove di stent-graft per la piegatura e l&#39;espansione. (A) stent-graft a pressare su un pallone a tre ante a 3 mm, (b) stent-graft ampliato per diametro progettato, e (c) stent-graft pressare e ampliato. Ogni divisione sulla scala rappresenta 0,5 mm.g5large.jpg &quot;target =&quot; _ blank &quot;&gt; Clicca qui per vedere una versione più grande di questa figura.

Watch this Scientific Journal Video about Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents at JoVE.com

Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents

In the protocol, we present a method to manufacture a small caliber stent-graft by sandwiching a balloon expandable stent between two electrospun nanofibrous polyurethane layers.

Fabbricazione di piccolo calibro e stent-innesti Uso Electrospinning e Balloon espandibili Bare Metal Stent

Stent-grafts are widely used for the treatment of various conditions such as aortic lesions, aneurysms, emboli due to coronary intervention procedures and ...

fabrication-small-caliber-stent-grafts-using-electrospinning-balloon

Nanyang Technological University

Research

JoVE Journal

Medicine

8.8K Views.  Mayo Clinic. In the protocol, we present a method to manufacture a small caliber stent-graft by sandwiching a balloon expandable stent between two electrospun nanofibrous polyurethane layers.

Video: Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents

Contrast Enhanced Vessel Imaging using MicroCT

Microscopic computed tomography (microCT) offers high-resolution volumetric imaging of the anatomy of living small animals. However, the contrast between different soft tissues and body fluids is inherently poor in micro-CT images 1. Under these circumstances, visualization of blood vessels becomes a nearly impossible task. To overcome this and to improve the visualization of blood vessels exogenous contrast agents can be used. Herein, we present a methodology for visualizing the vascular network in a rodent model. By using a long-acting aqueous colloidal polydisperse iodinated blood-pool contrast agent, eXIA 160XL, we optimized image acquisition parameters and volume-rendering techniques for finding blood vessels in live animals. Our findings suggest that, to achieve a superior contrast between bone and soft tissue from vessel, multiple-frames (at least 5-8/ frames per view), and 360-720 views (for a full 360&deg; rotation) acquisitions were mandatory. We have also demonstrated the use of a two-dimensional transfer function (where voxel color and opacity was assigned in proportion to CT value and gradient magnitude), in visualizing the anatomy and highlighting the structure of interest, the blood vessel network. This promising work lays a foundation for the qualitative and quantitative assessment of anti-angiogenesis preclinical studies using transgenic or xenograft tumor-bearing mice.

Contrast enhanced small animal vessel imaging by microCT is a rapid, cost-effective and high-throughput technique for serial in situ examination for tumor development, for analyzing the network of blood vessels that nourish them, and for following the response of tumors to preclinical therapeutic intervention(s).

Contrast Imaging nave migliorata utilizzando microCT

Microscopic computed tomography (microCT) offers high-resolution volumetric imaging of the anatomy of living small animals. However, the contrast between ...

Ricerca

Medicina

Protocol for Long Duration Whole Body Hyperthermia in Mice

Hyperthermia is a general term used to define the increase in core body temperature above normal. It is often used to describe the increased core body temperature that is observed during fever. The use of hyperthermia as an adjuvant has emerged as a promising procedure for tumor regression in the field of cancer biology. For this purpose, the most important requirement is to have reliable and uniform heating protocols. We have developed a protocol for hyperthermia (whole body) in mice. In this protocol, animals are exposed to cycles of hyperthermia for 90 min followed by a rest period of 15 min. During this period mice have easy access to food and water. High body temperature spikes in the mice during first few hyperthermia exposure cycles are prevented by immobilizing the animal. Additionally, normal saline is administered in first few cycles to minimize the effects of dehydration. This protocol can simulate fever like conditions in mice up to 12-24 hr. We have used 8-12 weeks old BALB/Cj female mice to demonstrate the protocol.

This paper describes a protocol for whole body hyperthermia in mice that can stimulate fever like conditions up to 12-24 hr.

Protocollo per lungo Ipertermia Corpo intera durata in Mouse

Hyperthermia is a general term used to define the increase in core body temperature above normal. It is often used to describe the increased core body ...

Vascular Balloon Injury and Intraluminal Administration in Rat Carotid Artery

The carotid artery balloon injury model in rats has been well established for over two decades. It remains an important method to study the molecular and cellular mechanisms involved in vascular smooth muscle dedifferentiation, neointima formation and vascular remodeling. Male Sprague-Dawley rats are the most frequently employed animals for this model. Female rats are not preferred as female hormones are protective against vascular diseases and thus introduce a variation into this procedure. The left carotid is typically injured with the right carotid serving as a negative control. Left carotid injury is caused by the inflated balloon that denudes the endothelium and distends the vessel wall. Following injury, potential therapeutic strategies such as the use of pharmacological compounds and either gene or shRNA transfer can be evaluated. Typically for gene or shRNA transfer, the injured section of the vessel lumen is locally transduced for 30 min with viral particles encoding either a protein or shRNA for delivery and expression in the injured vessel wall. Neointimal thickening representing proliferative vascular smooth muscle cells usually peaks at 2 weeks after injury. Vessels are mostly harvested at this time point for cellular and molecular analysis of cell signaling pathways as well as gene and protein expression. Vessels can also be harvested at earlier time points to determine the onset of expression and/or activation of a specific protein or pathway, depending on the experimental aims intended. Vessels can be characterized and evaluated using histological staining, immunohistochemistry, protein/mRNA assays, and activity assays. The intact right carotid artery from the same animal is an ideal internal control. Injury-induced changes in molecular and cellular parameters can be evaluated by comparing the injured artery to the internal right control artery. Likewise, therapeutic modalities can be evaluated by comparing the injured and treated artery to the control injured only artery.

This protocol uses a balloon catheter to cause an intraluminal injury on the rat carotid artery and henceforth elicit neointimal hyperplasia. This is a well-established model for studying the mechanisms of vascular remodeling in response to injury. It is also widely used to determine the validity of potential therapeutic approaches.

Vascolare Balloon Lesioni e intraluminale Amministrazione in Rat carotide

The carotid artery balloon injury model in rats has been well established for over two decades. It remains an important method to study the molecular and ...

A Rat Carotid Balloon Injury Model to Test Anti-vascular Remodeling Therapeutics

The rat carotid balloon injury is a well-established surgical model that has been used to study arterial remodeling and vascular cell proliferation. It is also a valuable model system to test, and to evaluate therapeutics and drugs that negate maladaptive remodeling in the vessel. The injury, or barotrauma, in the vessel lumen caused by an inflated balloon via an inserted catheter induces subsequent neointimal growth, often leading to hyperplasia or thickening of the vessel wall that narrows, or obstructs the lumen. The method described here is sufficiently sensitive, and the results can be obtained in relatively short time (2 weeks after the surgery). The efficacy of the drug or therapeutic against the induced-remodeling can be evaluated either by the post-mortem pathological and histomorphological analysis, or by ultrasound sonography in live animals. In addition, this model system has also been used to determine the therapeutic window or the time course of the administered drug. These studies can leadto the development of a better administrative strategy and a better therapeutic outcome. The procedure described here provides a tool for translational studies that bring drug and therapeutic candidates from bench research to clinical applications.

The rat carotid balloon injury model described below allows researchers to evaluate drugs or therapeutics that negate injury-induced arterial hyperplasia. Detailed pre-surgical preparation, surgical procedure, and post-surgical cares of the animal are described.

Un ratto carotidea Pallone Lesioni modello per verificare Therapeutics ritocca Anti-vascolari

The rat carotid balloon injury is a well-established surgical model that has been used to study arterial remodeling and vascular cell proliferation. It is ...

Balloon-based Injury to Induce Myointimal Hyperplasia in the Mouse Abdominal Aorta

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine balloon denudation model, which is comparable with established vessel injury models in large animals. The aorta denudation model with balloon catheters mimics the clinical setting and leads to comparable pathobiological and physiological changes. Briefly, after performing a horizontal incision in the aorta abdominalis, a balloon catheter will be inserted into the vessel, inflated, and introduced retrogradely. Inflation of the balloon will lead to intima injury and overdistension of the vessel. After removing the catheter, the aortic incision will be closed with single stiches. The model shown in this article is reproducible, easy to perform, and can be established quickly and reliably. It is especially suitable for evaluating expensive experimental therapeutic agents, which can be applied in an economical fashion. By using different knockout-mouse strains, the impact of different genes on MH development can be assessed.

This article demonstrates a murine model to study the development of myointimal hyperplasia (MH) after aortic balloon injury.

Basato su palloncino ferita per indurre iperplasia Myointimal nell'Aorta addominale di Mouse

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine ...

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The amount of the different tissues in the callus provides important information on the fracture healing progress. Available in vivo techniques to longitudinally monitor the callus tissue development in preclinical fracture-healing studies using small animals include digital radiography and &#181;CT imaging. However, both techniques are only able to distinguish between mineralized and non-mineralized tissue. Consequently, it is impossible to discriminate cartilage from fibrous tissue. In contrast, magnetic resonance imaging (MRI) visualizes anatomical structures based on their water content and might therefore be able to noninvasively identify soft tissue and cartilage in the fracture callus. Here, we report the use of an MRI-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice. The experiments demonstrated that the fixator and a custom-made mounting device allow repetitive MRI scans, thus enabling longitudinal analysis of fracture-callus tissue development.

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

The evaluation of tissue development in the fracture callus during endochondral bone healing is essential to monitor the healing process. Here, we report the use of a magnetic resonance imaging (MRI)-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice.

In Vivo Valutazione dello sviluppo di callo di frattura durante la guarigione dell'osso nei topi utilizzando un MRI-compatibile con osteosintesi per il femore di Mouse

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The ...

Mechanisms Underlying Gut Hormone Secretion Using the Isolated Perfused Rat Small Intestine

The gut is the largest endocrine organ of the body, producing more than 15 different peptide hormones that regulate appetite and food intake, digestion, nutrient absorption and distribution, and post-prandial glucose excursions. Understanding the molecular mechanisms that regulate gut hormone secretion is fundamental for understanding and translating gut hormone physiology. Traditionally, the mechanisms underlying gut hormone secretion are either studied in vivo (in experimental animals or humans) or using gut hormone-secreting primary mucosal cell cultures or cell lines. Here, we introduce an isolated perfused rat small intestine as an alternative method for studying gut hormone secretion. The virtues of this model are that it relies on the intact gut, meaning that it recapitulates most of the physiologically important parameters responsible for the secretion in in vivo studies, including mucosal polarization, paracrine relationships and routes of perfusion/stimulus exposure. In addition, and unlike in vivo studies, the isolated perfused rat small intestine allows for almost complete experimental control and direct assessment of secretion. In contrast to in vitro studies, it is possible to study both the magnitude and the dynamics of secretion and to address important questions, such as what stimuli cause secretion of different gut hormones, from which side of the gut (luminal or vascular) is secretion stimulated, and to analyze in detail molecular sensors underlying the secretory response. In addition, the preparation is a powerful model for the study of intestinal absorption and details regarding the dynamics of intestinal absorption including the responsible transporters.

Here, we present a powerful and physiological model to study the molecular mechanisms underlying gut hormone secretion and intestinal absorption &#8212; the isolated perfused rat small intestine.

Meccanismi di secrezione dell'ormone intestinale utilizzando l'isolato irrorati intestino tenue del ratto

The gut is the largest endocrine organ of the body, producing more than 15 different peptide hormones that regulate appetite and food intake, digestion, ...

Implantation of Human-Sized Coronary Stents into Rat Abdominal Aorta Using a Trans-Femoral Access

Percutaneous coronary intervention (PCI), combined with the deployment of a coronary stent, represents the gold standard in interventional treatment of coronary artery disease. In-stent restenosis (ISR) is determined by an excessive proliferation of neointimal tissue within the stent and limits the long-term success of stents. A variety of animal models have been used to elucidate pathophysiological processes underlying in-stent restenosis (ISR), with the porcine coronary and the rabbit iliac artery models being the most frequently used. Murine models provide the advantages of high throughput, ease of handling and housing, reproducibility, and a broad availability of molecular markers. The apolipoprotein E deficient (apoE-/- ) mouse model has been widely used to study cardiovascular diseases. However, stents must be miniaturized to be implanted into mice, involving important changes of their mechanical and (potentially) biological properties. The use of apoE-/- rats can overcome these shortcomings as apoE-/- rats allow for the evaluation of human-sized coronary stents while at the same time providing an atherogenic phenotype. This makes them an excellent and reliable model to investigate ISR after stent implantation. Here, we describe, in detail, the implantation of commercially available human coronary stents into the abdominal aorta of rats with an apoE-/- background using a trans-femoral access.

This protocol describes the implantation of human coronary stents into the abdominal aorta of rats with an apoE-/- background using a trans-femoral access. Compared with other animal models, murine models carry the advantages of high throughput, reproducibility, ease of handling and housing, and a broad availability of molecular markers.

Impianto di stent coronari di dimensioni umane nell'aorta addominale del ratto utilizzando un accesso trans-femorale

Percutaneous coronary intervention (PCI), combined with the deployment of a coronary stent, represents the gold standard in interventional treatment of ...

The Intra-Aortic Balloon Pump

Cardiogenic shock remains one of the most challenging clinical syndromes in modern medicine. Mechanical support is being increasingly used in the management of cardiogenic shock. Intra-aortic balloon pump (IABP) is one of the earliest and most widely used types of mechanical circulatory support. The device acts by external counterpulsation and uses systolic unloading and diastolic augmentation of aortic pressure to improve hemodynamics. Although IABP provides less hemodynamic support when compared with newer mechanical circulatory support devices, it can still be the mechanical support device of choice in appropriate situations because of its relative simplicity of insertion and removal, need for smaller size vascular access and better safety profile. In this review, we discuss the equipment, procedural and technical aspects, hemodynamic effects, indications, evidence, current status and recent advances in the use of IABP in cardiogenic shock.

We describe the steps for the percutaneous implantation of the intra-aortic balloon pump (IABP), a mechanical circulatory support device. It acts by counterpulsation, inflating at the onset of diastole, augmenting diastolic aortic pressure and improving coronary blood flow and systemic perfusion, and deflating before systole, reducing left ventricular afterload.

La pompa a palloncino intra-aortica

Cardiogenic shock remains one of the most challenging clinical syndromes in modern medicine. Mechanical support is being increasingly used in the ...

Combining 3D-Printing and Electrospinning to Manufacture Biomimetic Heart Valve Leaflets

Electrospinning has become a widely used technique in cardiovascular tissue engineering as it offers the possibility to create (micro-)fibrous scaffolds with adjustable properties. The aim of this study was to create multilayered scaffolds mimicking the architectural fiber characteristics of human heart valve leaflets using conductive 3D-printed collectors.
Models of aortic valve cusps were created using commercial computer-aided design (CAD) software. Conductive polylactic acid was used to fabricate 3D-printed leaflet templates. These cusp negatives were integrated into a specifically designed, rotating electrospinning mandrel. Three layers of polyurethane were spun onto the collector, mimicking the fiber orientation of human heart valves. Surface and fiber structure was assessed with a scanning electron microscope (SEM). The application of fluorescent dye additionally permitted the microscopic visualization of the multilayered fiber structure. Tensile testing was performed to assess the biomechanical properties of the scaffolds.
3D-printing of essential parts for the electrospinning rig was possible in a short time for a low budget. The aortic valve cusps created following this protocol were three-layered, with a fiber diameter of 4.1 &#177; 1.6 &#181;m. SEM imaging revealed an even distribution of fibers. Fluorescence microscopy revealed individual layers with differently aligned fibers, with each layer precisely reaching the desired fiber configuration. The produced scaffolds showed high tensile strength, especially along the direction of alignment. The printing files for the different collectors are available as Supplemental File 1, Supplemental File 2, Supplemental File 3, Supplemental File 4, and Supplemental File 5.
With a highly specialized setup and workflow protocol, it is possible to mimic tissues with complex fiber structures over multiple layers. Spinning directly on 3D-printed collectors creates considerable flexibility in manufacturing 3D shapes at low production costs.

The presented method offers an innovative way for engineering biomimetic fiber structures in three-dimensional (3D) scaffolds (e.g., heart valve leaflets). 3D-printed, conductive geometries were used to determine shape and dimensions. Fiber orientation and characteristics were individually adjustable for each layer. Multiple samples could be manufactured in one setup.

Combinazione di stampa 3D ed elettrofilatura per la produzione di volantini biomimetici per valvole cardiache

Electrospinning has become a widely used technique in cardiovascular tissue engineering as it offers the possibility to create (micro-)fibrous scaffolds ...