Fabricage van klein kaliber Stent-enten met behulp van Electrospinning en Balloon Expandable Bare Metal Stents
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
Coronaire interventie procedures leiden tot significante vaatwand letsel als gevolg van verstoring van de plaque en vaatwand. Dit leidt tot restenose, perifere embolie bij vaatprothesen en discontinuïteit van coronaire lumen 1-4. Om deze complicaties te vermijden, wordt een veelbelovende strategie voor het vasculaire oppervlak in de angioplastie, die mogelijk restenose zal remmen, verminderen risico van discontinuïteit van vatlumen en voorkomen perifere embolie dekken. Eerdere studies hebben kale metalen stents ten opzichte van stent-grafts met positieve resultaten voor stent-grafts 5. Onderzoekers hebben diverse materialen gebruikt om membranen te vervaardigen om de stents te dekken. Dit omvat synthetische materialen zoals polyethyleen tetraphthalate (PET), polytetrafluorethyleen (PTFE), polyurethaan (PU) en silicium of autoloog vaatweefsel gedekt stents 6-9 vervaardigen. Een ideaal entmateriaal gebruikt om de stent te worden bekeken trombi, non-biodegradable, en moet integreren met inheemse weefsel zonder overmatige proliferatie en ontsteking 10. Het graftmateriaal wordt gebruikt om de stent te bedekken ook genezing te bevorderen van de stent-graft.
Stent-grafts worden veel gebruikt voor de behandeling van aorta coarctatio, pseudo-aneurysmen van de halsslagader, arterioveneuze fistels, gedegenereerd veneuze omleidingen en groot om grote cerebrale aneurysma. Maar de ontwikkeling van klein kaliber stent-grafts is beperkt door het vermogen laag profiel en flexibiliteit, die helpt bij het inzetten van de stent-grafts 11-14 behouden. PU een elastomeer polymeer met goede mechanische sterkte die een gewenste eigenschap voor het bereiken van een laag profiel en goede flexibiliteit 15,16. Naast het hebben van goede deliverability, moet stent-grafts bevorderen ook snelle genezing en endothelialisatie. PU bedekte stent-transplantaten beter biocompatibiliteit aangetoond en verbeterde endothelialisatie 17. onderzoekers hebbeneerder geprobeerd endothelialize PU bedekte stent-grafts door ze enten met endotheelcellen 17. Electrospinning PU te maken nanovezeloppervlakken matrix is aangetoond dat het een waardevolle techniek voor de productie van vasculaire transplantaten 18,19. Het bestaan van nanovezels dat de architectuur van natieve extracellulaire matrix nabootsen is ook bekend om endotheliale celproliferatie 20,21 promoten. Electrospinning maakt ook controle over de dikte van het materiaal 22. Klein kaliber vasculaire transplantaten van PU zijn bestudeerd om genezing te bevorderen met modificaties zoals oppervlaktecoatings anticoagulantia en celproliferatie suppressants. Al deze wijzigingen zijn ontworpen om gastheer acceptatie bemiddelen en het bevorderen van graft genezing 23.
Onze fractie heeft een ballon uitzetbare kale metalen stent, die kunnen worden ingezet in diermodellen 24-26 ontwikkeld. De combinatie van een electrospun polyurethaan mesh en een baloon expandeerbare stent konden wij klein kaliber ballon expandeerbare stent-grafts genereren. De meeste momenteel beschikbare stent-grafts worden ingebracht via de femorale slagader gedurende een interventionele procedure, maar slechts enkele commercieel behandelde stents kunnen worden ingebracht 1 French maten groter dan die van een niet-opgeblazen ballon 27. In deze studie hebben we een klein kaliber vasculaire stent-graft ontwikkeld door inkapselen van een ballon expandeerbare stent tussen twee lagen electrospun PU die een kransslagader met een standaard 8-9 French geleidekatheter in een percutane interventionele procedure kan worden geleverd.
Protocol
Representative Results
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 …
Declarações
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 |
Referências
- Elsner, M., et al. Coronary stent grafts covered by a polytetrafluoroethylene membrane. Am. J. Cardiol. 84 (3), 335-338 (1999).
- Störger, H., Haase, J. Polytetrafluoroethylene-Covered Stents: Indications, Advantages, and Limitations. J. Interv. Cardiol. 12 (6), 451-456 (1999).
- Moreno, P. R., et al. Macrophage infiltration predicts restenosis after coronary intervention in patients with unstable angina. Circulation. 94 (12), 3098-3102 (1996).
- 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).
- 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).
- 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).
- Geremia, G., et al. Experimental arteriovenous fistulas: treatment with silicone-covered metallic stents. AJNR. Am. J. Neuroradiol. 18 (2), 271-277 (1997).
- 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).
- Stefanadis, C., et al. Stents Wrapped in Autologous Vein: An Experimental Study1. J. Am. Coll. Cardiol. 28 (4), 1039-1046 (1996).
- Palmaz, J. C. Review of polymeric graft materials for endovascular applications. J. Vasc. Interv. Radiol. 9, 7-13 (1998).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).
- Gibson, P., Schreuder-Gibson, H., Rivin, D. Transport properties of porous membranes based on electrospun nanofibers. Colloid Surf., A. 187, 469-481 (2001).
- Zdrahala, R. J. Small caliber vascular grafts. Part II: Polyurethanes revisited. J. Biomater. Appl. 11 (1), 37-61 (1996).
- 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).
- Tefft, B. J., et al. Cell Labeling and Targeting with Superparamagnetic Iron Oxide Nanoparticles. J. Vis. Exp. (105), e53099 (2015).
- Uthamaraj, S., et al. Ferromagnetic Bare Metal Stent for Endothelial Cell Capture and Retention. J. Vis. Exp. (103), e53100 (2015).
- de Giovanni, J. V. Covered stents in the treatment of aortic coarctation. J. Interv. Cardiol. 14 (2), 187-190 (2001).
- 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).
- Hasan, A., et al. Electrospun scaffolds for tissue engineering of vascular grafts. Acta. Biomater. 10 (1), 11-25 (2014).
