Ferromagnetische Bare Metal Stent für Endothelzellen-Abscheidung und Retention
Summary
Unser Ziel war es, entwickeln, produzieren und testen ferro Stents für Endothelzellen-Capture. Zehn Stents wurden zur Fraktur getestet und 10 weitere Stents wurden für einbehaltene Magnetismus getestet. Schließlich wurden 10 Stents in vitro getestet und 8 weitere Stents wurden in 4 Schweinen implantiert, um die Zellaufnahme und Retention zu zeigen.
Abstract
Schnelle Endothelialisierung kardiovaskuläre Stents erforderlich ist, um Stent-Thrombose zu verringern und die Anti-Thrombozyten-Therapie, die das Blutungsrisiko zu verringern, zu vermeiden. Die Durchführbarkeit der Verwendung von magnetischen Kräfte zu erfassen und behalten endothelialen Zellen Auswuchs (EOC) mit Super-paramagnetische Eisenoxid-Nanopartikel (SPION) markiert wurde zuvor gezeigt. Aber diese Technik erfordert die Entwicklung eines mechanisch funktionale Stent aus einem magnetischen und biokompatiblen Material, gefolgt von in-vitro und in-vivo-Tests, um eine schnelle Endothelisierung zu beweisen. Wir entwickelten ein schwach ferromagnetischen Stent aus 2205 Duplex-Edelstahl mit Computer Aided Design (CAD) und sein Design wurde weiter unter Verwendung von Finite-Elemente-Analyse (FEA) verfeinert. Das endgültige Design des Stents zeigten eine Hauptdehnung unterhalb der Bruchgrenze des Materials bei der mechanischen Crimpen und Expansion. Einhundert Stents wurden hergestellt und eine Teilmenge davon wurde für die mechanische Prüfung, ret verwendetained Magnetfeldmessungen, in-vitro Zelleinfang Studien und in-vivo-Implantation Studien. Zehn Stents wurden für den Einsatz getestet, um zu überprüfen, ob sie anhalt Crimpen und Expansionszyklus ohne Ausfall. Weitere 10 Stents wurden unter Verwendung einer starken Neodym-Magneten magnetisiert und ihre beibehalten Magnetfeld gemessen. Die Stents zeigten, dass die zurückgehalten Magnetismus war ausreichend, um SPION-markierten EOC in unserer In-vitro-Studien zu erfassen. SPION-markierten EOC-Abscheidung und Retention wurde in Großtiermodellen durch Implantation von 1 magnetisierten Stent und 1 nicht-magnetisierten Kontrollstent in jedem der 4 Schweinen nachgewiesen. Stent versehenen Arterien wurden nach 7 Tagen explantiert und histologisch ausgewertet. Die in dieser Studie entwickelt schwach magnetischen Stents waren in der Lage, die Gewinnung und Bindung SPION-markierten Endothelzellen, die schnelle Heilung fördern können.
Introduction
Patients implanted with vascular stents manufactured from thrombogenic materials like stainless steel, cobalt chromium, and platinum chromium – both bare metal stents (BMS) and drug eluting stents (DES) – need anti-platelet therapy to prevent thrombus formation. BMS heal rapidly, but are subject to late stage restenosis due to incomplete healing. DES require long term anti-platelet therapy due to delayed healing. Anti-platelet therapy administered to avoid thrombosis as a result of incomplete or delayed healing leads to increased bleeding risk and may not be suitable for certain patients1,2. An ideal stent will heal completely and quickly thus avoiding long-term anti-platelet therapy and late stage restenosis. This complete healing can only be achieved if the stent is rapidly coated with a monolayer of endothelial cells after implantation. Coating the stents with biocompatible materials such as gold or other biopolymers has been shown to improve thrombo-resistance, but none of these techniques achieved ideal blood compatibility as may be possible by coating with endothelial cells3,4.
A stent can be coated with endothelial cells post implantation by attracting circulating progenitor cells. This self-seeding technique can be achieved by utilizing ligands and antibodies. But this technique is limited by the low number of circulating endothelial progenitor cells. A promising strategy is to deliver cells directly to the stent immediately following implantation during a short period of blood flow occlusion3,5. This strategy requires a technique for rapidly capturing cells and retaining them on the stent even after restoring blood flow. We have developed a technique in which a magnetic stent is used to attract and retain magnetically-labeled endothelial cells delivered post implantation. To achieve this, a functional BMS with sufficient magnetic properties to capture and retain magnetically-labeled endothelial cells is required6.
In this paper, we discuss the methods for designing, manufacturing, and testing a 2205 stainless steel stent. The stents were designed using CAD and FEA. The manufactured stents were magnetized using a neodymium magnet and the retained magnetic field was measured using a magneto-resistance microsensor probe. We then tested the stents for magnetically-labeled cell capture in a culture dish during our in-vitro experiments. Finally, the stents were tested in-vivo by implanting magnetic and non-magnetic stents in 4 pigs and histologically analyzing the stented arteries.
Protocol
Representative Results
Discussion
Wir entwickelten eine magnetische Stent, der als ein Bare-Metal-Stent funktionieren kann und SPION-markierten Endothelzellen zu gewinnen. In früheren Studien, bei denen magnetische Stents haben Forscher vernickelt kommerziellen Stents und Spulen oder Maschen aus magnetischen Materialien bestehen aufgrund der Nichtverfügbarkeit eines ferromagnetischen Stent 5,10-14 verwendet. Andere Gruppen haben auch für die Ausrichtung von Nanopartikeln beladen Endothelzellen 3 verwendet die paramagnetischen Ch…
Declarações
The authors have nothing to disclose.
Acknowledgements
The authors thank Tyra Witt, Cheri Mueske, Brant Newman and Dr. Peter J. Psaltis, MBBS, PhD for their valuable contributions. This study was financially supported by European Regional Development Fund – FNUSA-ICRC (No. CZ.1.05/1.100/02.0123), American Heart Association Scientist Development Grant (AHA #06-35185N), National Institutes of Health (T32HL007111) and The Grainger Innovation Fund – Grainger Foundation.
Materials
| 2205 Stainless steel | Carpenter Technology Corporation | N/A | Round bar stock material |
| Abaqus | Dassault systems | N/A | Software |
| Atropine | Prescription drug. | ||
| Clopidogrel | Commercial name: Plavix. Prescription drug. | ||
| CM-DiI | Life Technologies | V-22888 | Molecular Probes, Eugene, OR |
| Endothelial growth medium-2 | Lonza | CC-3162 | |
| Hand Held Crimping tool | Blockwise engineering | M1-RMC | |
| Hydrochloric acid (HCl) | Sigma Aldrich | MFCD00011324 | CAUTION: wear proptective equipment and handle under fume hood |
| Isoflurane anesthesia | Piramal Critical Care, Inc. | ||
| Isopropyl alcohol | Sigma Aldrich | MFCD00011674 | |
| NdFeB magnet 2" Dia x 1" thick | Amazing magnets | D1000P | Axially magnetized disc magnet with poles on flat faces |
| Over-The-Wire trifold balloon | N/A | N/A | Any commercially available OTW trifold balloon can be used |
| Phosphate buffered saline | Life Technologies | 10010-023 | Commonly known as PBS |
| Sodium Bicarbonate (NaHCO3) | Sigma Aldrich | MFCD00003528 | |
| Sodium pentobarbital | Zoetis | Commercial Name: Sleepaway (26%), FatalPlus, Beuthanasi. Controlled substance to be ordered only by licensed veternarian | |
| SolidWorks | Dassault systems | N/A | Software |
| SpinTJ-020 micro sensor | MicroMagneitcs Sensible Solutions | N/A | Long probe STJ-020 microsensor |
| SPION | Mayo Clinic | N/A | Nanoparticles synthesized internally (Ref: Lee, S. J. et al. Nanoparticles of magnetic ferric oxides encapsulated with poly(D,L latide-co-glycolide) and their applications to magnetic resonance imaging contrast agent. J Magn Magn Mater 272, 2432-2433, doi:DOI 10.1016/j.jmmm.2003.12.416 (2004)) |
| Telazol | Zoetis | Controlled substance to be ordered only by licensed veternarian | |
| Trypsin EDTA | Life Technologies | 25200-056 | Gibco, Grand Island, NY |
| Xylazine | Bayer Animal Health | Commercial name: Rompun. Controlled sunstance to be ordered only by a licensed veternarian |
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