Ферромагнитный Bare Metal Стент для эндотелиальных клеток Capture и удержания
Summary
Наши цели были разрабатываем, производим и проверить ферромагнитных стентов для захвата эндотелия клеток. Десять стенты были испытаны на разрыв и более 10 стентов были испытаны при задержке магнетизма. Наконец, 10 стентов были испытаны в пробирке и более 8 стенты были имплантированы в 4 свиней, чтобы показать захват и удержание клеток.
Abstract
Быстрое эндотелиализацию сердечно-сосудистых стентов необходимо для снижения тромбоза стента и избежать анти-тромбоцитов терапии, которые могут уменьшить риск кровотечений. Возможность использования магнитных сил, чтобы захватить и удержать эндотелиальные клетки вырост (EOC), меченные супер парамагнитные наночастицы оксида железа (Spion) было показано ранее. Но этот метод требует разработки механически функциональной стента из магнитного материала и биологически совместимого с последующим в пробирке и в естественных испытаний, чтобы доказать, быстрое эндотелиализацию. Мы разработали слабоферромагнитное стент из 2205 дуплексной нержавеющей стали с использованием системы автоматизированного проектирования (САПР) и его дизайн был доработан с помощью конечно-элементного анализа (FEA). Окончательный дизайн стента выставлены основной нагрузки ниже предела разрушения материала во время механического обжатия и расширения. Сто стенты были изготовлены и подмножество из них используется для механических испытаний в отставкеained измерения магнитного поля, в-пробирке исследования захвата клеток и в естественных имплантации исследований. Десять стенты были испытаны для развертывания, чтобы убедиться, если они понесли опрессовки и расширение цикл без сбоев. Еще 10 стентов были намагничены с помощью сильной неодимовый магнит и их сохранил магнитное поле было измерено. Стенты показал, что сохраняется магнетизм было достаточно, чтобы захватить Spion-меченого EOC в наших в пробирке исследований. Spion меченных захвата и удержания ЕОК была проверена в крупных животных моделях имплантации стента 1 намагниченной и 1 не-намагниченной стента управления в каждом из 4 свиней. Стентированной артерии эксплантировали через 7 дней и анализировали гистологически. В слабомагнитные стенты, разработанные в этом исследовании, были способны привлекать и удерживать Spion меченных эндотелиальные клетки, которые могут способствовать быстрому заживлению.
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
Мы разработали магнитную стента, который может функционировать в качестве голой металлических стентов и может привлечь Spion меченных эндотелиальные клетки. В предыдущих исследованиях с участием магнитных стентов, исследователи использовали никель покрытием коммерческие стенты и кат…
Offenlegungen
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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