Summary

Fremstilling af små Caliber stentimplantater Brug Electrospinning og Balloon kan udvides Bare Metal Stents

Published: October 26, 2016
doi:

Summary

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.

Abstract

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.

Introduction

Koronar intervention procedurer forårsage betydelig karvæggen skade som følge af afbrydelse af plak og karvæggen. Dette resulterer i restenose, perifer emboli hos vene transplantater, og diskontinuitet af koronare lumen 1-4. For at undgå disse komplikationer, vil en lovende strategi være at dække den vaskulære overflade i angioplastik site, som potentielt vil hæmme restenose, mindske risici fra diskontinuitet af fartøjets lumen, og forhindre perifer emboli. Tidligere undersøgelser har sammenlignet nøgne metal stents til stentimplantater med positive resultater for stentimplantater 5. Forskere har brugt flere materialer til at fremstille membraner til at dække stents. Dette omfatter syntetiske materialer som polyethylentetraphthalat (PET), polytetrafluorethylen (PTFE), polyurethan (PU), og silicium eller autologt kar væv til fremstilling dækket stenter 6-9. En ideel graft materiale, der anvendes til at dække stenten bør tromboresistent, ikke-biodegradable, og bør integrere med indfødte væv uden overdreven spredning og inflammation 10. Implantatmaterialet anvendes til at dække stenten skal også fremme heling af stent-implantatet.

Stentimplantater er almindeligt anvendt til behandling af aorta coarctatio, pseudo-aneurismer af halspulsåren, arteriovenøs fistler, degenereret vene transplantater, og store til giant cerebrale aneurismer. Men udviklingen af små kaliber stentimplantater er begrænset af evnen til at opretholde lav profil og fleksibilitet, som hjælper med indsættelse af de stentimplantater 11-14. PU er en elastomer polymer med god mekanisk styrke, som er et ønsket træk for at opnå en lav profil og god fleksibilitet 15,16. Ud over at have god overdragelsen, bør stentimplantater også fremme hurtig heling og endothelialisering. PU dækket stentimplantater har vist bedre biokompatibilitet og øget endothelialisering 17. Forskere hartidligere forsøgt at endothelialize PU dækket stentimplantater ved podning dem med endotelceller 17. Elektrospinning af PU at skabe nanofiber matrix har vist sig at være en værdifuld teknik til fremstilling af vaskulære transplantater 18,19. Eksistensen af nanofibre, der efterligner arkitekturen i native ekstracellulære matrix er også kendt for at fremme endothelcelleproliferation 20,21. Elektrospinning tillader også kontrol over materialets tykkelse 22. Lille kaliber vaskulære transplantater fremstillet af PU er blevet undersøgt for at fremme heling ved hjælp modifikationer, såsom overfladebelægninger, antikoagulantia, og celleproliferation suppressants. Alle disse ændringer er designet til at mægle vært accept og fremme graft healing 23.

Vores gruppe har udviklet en ballon udvides bare metal stent, der kan implementeres i dyremodeller 24-26. Kombinationen af ​​en elektrospundet polyurethan mesh og en boldoon stent har gjort det muligt for os at generere små kaliber ballon udvides stentimplantater. De fleste af de aktuelt tilgængelige stentimplantater indføres gennem lårarterien under en interventionel procedure, men kun få kommercielle dækket stenter kan indføres 1 fransk størrelse større end den, der kræves for en un-oppustet ballon 27. I denne undersøgelse har vi udviklet et lille kaliber vaskulær stent-implantatet ved indkapsling en ballon stent mellem to lag elektrospundet PU, som kan leveres til en koronararterie anvendelse af et standard 8-9 fransk ledekateter i en perkutan indgrebsprocedure.

Protocol

1. Electrospinning Polyuretan på Dorn Collector Forbered dorn for elektrospinning Smelt ca. 8 ml biokompatible, fødevarekvalitet, vandopløseligt bæremateriale i en gradueret cylinder (ca. 9 mm i diameter og 110 mm dyb) ved 155 ° C under anvendelse af en ovn. Dyp et 3 mm i diameter og 100 mm lang rustfri stål dorn for at opnå en belægning af bæremateriale på overfladen af ​​dornen. Før dypning, placere dornene i ovnen ved 155 ° C i ca. 15 min for at hæve tem…

Representative Results

Vores electrospinner opsætningen (figur 1) har resulteret i høj kvalitet polyurethan nanofibre (figur 2). En stent-implantatet er fremstillet ved elektrospinding et indre lag af polyurethan på en dorn, glider en bare metal stent i dette lag, og elektrospinding et andet ydre lag af polyurethan (figur 3). Polyurethan nanofibers elektrospindes med en hastighed på 50 um / time, hvilket resulterer i et indre lag af 100 um og et ydre lag af 150 pm på stentimplantat…

Discussion

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 …

Disclosures

The authors have nothing to disclose.

Acknowledgements

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.

Materials

Glass syringe Air Tite 7.140-33 Syringe for spinneret
Graduated cylinder 5 mL Fisher Scientific 08-552-4G 5 mL pyrex graduated cylinder about 9mm diameter and 11 cm long
High voltage generator Bertan Accociates, Inc. 205A-30P Used to apply voltage difference across spinneret and collector
Laboratory mixer with rpm control Scilogex SCI-84010201 Available from various laboratory equipment suppliers
Polyurethane DSM BioSpan SPU Biospan Segmented Polyurethane
Rubber sheet McMaster Carr 1370N11 Used to insulate syringe during electrospinning
Stainless steel mandrel N/A N/A Manufactured 
Stainless steel needle Hamilton 91018 Used as spinneret in electrospinning
Support material EnvisionTec B04-HT-DEMOMAT Biocompatible water soluble material
Syringe Pump Harvard Apparatus 55-3333

References

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

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Cite This Article
Uthamaraj, S., Tefft, B. J., Jana, S., Hlinomaz, O., Kalra, M., Lerman, A., Dragomir-Daescu, D., Sandhu, G. S. Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents. J. Vis. Exp. (116), e54731, doi:10.3791/54731 (2016).

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