Endotel Hücre yakalama ve Saklanmasına İlişkin ferromanyetik Bare Metal Stent
Summary
Hedeflerimiz, tasarlamak, üretmek ve endotel hücre yakalama için ferromanyetik stent test edildi. On stent kırığı için test edildi ve 10 daha fazla stent muhafaza manyetik için test edildi. Nihayet, 10 stent in vitro test edildi ve 8 daha stent hücre yakalama ve tutma göstermek için 4 domuzlarda implante edildi.
Abstract
Kardiyovasküler stentlerin hızlı endotelizasyonunun stent trombozu azaltmak ve kanama riskini azaltabilir, anti-trombosit tedavisi önlemek için gereklidir. Süper paramanyetik demir oksit nanopartiküller (casus) ile işaretlenmiş endotel hücreleri akıbet (EOC) yakalamak ve korumak için manyetik kuvvetler kullanarak fizibilite önceden gösterilmiştir. Ancak bu teknik, hızlı endotelizasyon kanıtlamak için in vitro ve in vivo test ardından manyetik ve biyo-uyumlu bir malzemeden, mekanik olarak işlevsel bir stent geliştirilmesini gerektirmektedir. Biz bilgisayar destekli tasarım (CAD) kullanarak 2205 dubleks paslanmaz çelikten zayıf ferromanyetik stent geliştirdi ve tasarımı daha da sonlu elemanlar analizi (FEA) kullanılarak rafine edilmiştir. Stentin nihai tasarım, mekanik kıvırma ve genişleme sırasında malzemenin kırılma sınırının altında bir ana zorlanma sergiledi. Yüz stent imal edildi ve bunların bir alt kümesi mekanik test, ret kullanılmıştırained manyetik alan ölçümleri, in-vitro hücre yakalama çalışmaları ve in vivo implantasyon çalışmaları. On stent onlar arızasız döngüsünü sıkma ve genişleme sürdürülebilir olmadığını doğrulamak için dağıtım için test edildi. Başka bir 10 stentler, güçlü bir neodimyum mıknatıs kullanarak mıknatıslanmamış ve bunların muhafaza manyetik alan ölçüldü. Stentler muhafaza manyetizma eden in vitro çalışmalarda spion etiketli EOC yakalamak için yeterli olduğunu göstermiştir. Spion etiketli EOC yakalama ve tutma 1 manyetize stent ve 4 domuz her 1 olmayan manyetize edilmiş kontrol stent implante büyük hayvan modellerinde doğrulanmıştır. Stentli arterler 7 gün sonra eksplante ve histolojik olarak incelendi. Bu çalışmada geliştirilen zayıf manyetik stentler çeken ve hızlı iyileşmeyi teşvik edebilir spion etiketli endotel hücrelerini tutabilen idi.
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
Biz çıplak metal stent olarak işlev görebilir ve casus etiketli endotel hücrelerini çekebilecek bir manyetik stent geliştirdi. Manyetik stent kapsayan önceki çalışmalarda, araştırmacılar nedeniyle ferromanyetik stent 5,10-14 olmayışı manyetik malzemelerden yapılmış nikel kaplamalı ticari stent ve bobinler veya kafesleri kullandık. Diğer gruplar da nanoparçacık yüklü endotel hücrelerini 3 hedefleme için piyasada mevcut 304 kalite paslanmaz çelik stent paramanyetik doğa…
Divulgations
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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