Ferromagnetiska Bare Metal Stent för Endothelial Cell Capture och retention
Summary
Våra mål var att konstruera, tillverka och testa ferromagnetiska stentar för endotelceller fånga. Tio stentar testades för brott och ytterligare 10 stentar testades för behålls magnetism. Slutligen har 10 stentar testades in vitro och ytterligare 8 stentar implanterades i 4 grisar för att visa fånga och behålla cell.
Abstract
Det krävs snabba endotelialisering av kardiovaskulära stentar för att minska stenttrombos och undvika trombocythämmande behandling som kan minska risk för blödning. Möjligheten att använda magnetiska krafter för att fånga och behålla endotelceller utväxt celler (EOC) märkta med superparamagnetiska järnoxid nanopartiklar (spion) har visats tidigare. Men denna teknik kräver att man utvecklar en mekaniskt fungerande stent från en magnetisk och biokompatibelt material, följt av in vitro och in vivo tester för att bevisa snabb endotelisering. Vi utvecklade en svagt ferromagnetiskt stent från 2205 duplex rostfritt stål med hjälp av datorstödd konstruktion (CAD) och dess utformning ytterligare förfinas med användning av finit elementanalys (FEA). Den slutliga utformningen av stenten uppvisade en huvudstam nedanför brottgränsen för materialet under mekanisk krympning och expansion. Hundra stentar tillverkades och en delmängd av dem användes för mekanisk provning, retained magnetiska fältmätningar, in-vitro cell fånga studier och in vivo implantatstudier. Tio stentar testades för distribution för att kontrollera om de ihållande pressning och expansionscykel utan fel. Ytterligare 10 stentar magnetiseras med hjälp av en stark neodymiummagnet och deras behållit magnetfält mättes. Stentarna visade att det kvarhållna magnetism var tillräckligt för att fånga Spion-märkt EOC i vår i-vitro-studier. Spion-märkt EOC infångning och kvarhållande verifierades i stora djurmodeller genom att implantera en magnetiserad stent och en icke-magnetiserade kontroll stent i varje 4 grisar. De stentade artärer explanterades efter 7 dagar och analyserades histologiskt. De svagt magnetiska stentar som utvecklats i denna studie var i stånd att attrahera och behålla Spion-märkta endotelceller som kan främja en snabb läkning.
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
Vi utvecklade ett magnetiskt stent som kan fungera som en ren metall stent och kan attrahera Spion märkta endotelceller. I tidigare studier med magnetiska stentar, har forskarna använt nickel belagda kommersiella stentar och spolar eller nät tillverkade av magnetiska material på grund av avsaknad av ett ferromagnetiskt stent 5,10-14. Andra grupper har också använt den paramagnetiska natur kommersiellt tillgängliga stentar 304-rostfritt stål för inriktning nanopartiklar laddad endotelceller 3.</s…
Disclosures
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 |
References
- Garg, S., Serruys, P. W. Coronary stents: current status. J Am Coll Cardiol. 56, 1-42 (2010).
- Austin, D., et al. Drug-eluting stents versus bare-metal stents for off-label indications: a propensity score-matched outcome study. Circ Cardiovasc Interv. 1 (1), 45-52 (2008).
- Polyak, B., et al. High field gradient targeting of magnetic nanoparticle-loaded endothelial cells to the surfaces of steel stents. P Natl Acad Sci USA. 105 (2), 698-703 (2008).
- Tassiopoulos, A. K., Greisler, H. P. Angiogenic mechanisms of endothelialization of cardiovascular implants: a review of recent investigative strategies. J Biomat Sci-Polym E. 11 (11), 1275-1284 (2000).
- Pislaru, S. V., et al. Magnetic forces enable rapid endothelialization of synthetic vascular grafts. Circulation. 114, I314-I318 (2006).
- 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).
- Gulati, R., et al. Diverse origin and function of cells with endothelial phenotype obtained from adult human blood. Circ Res. 93 (11), 1023-1025 (2003).
- 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 (3 Special Issue), 2432-2433 (2004).
- Lee, S. J., et al. Magnetic enhancement of iron oxide nanoparticles encapsulated with poly(D,L-latide-co-glycolide). Colloid Surface A. (1-3), 255-251 (1016).
- Forbes, Z. G., et al. Locally targeted drug delivery to magnetic stents for therapeutic applications. Computer Architectures for Machine Perception, 2003 IEEE International Workshop on. , 1-6 (2003).
- Rathel, T., et al. Magnetic Stents Retain Nanoparticle-Bound Antirestenotic Drugs Transported by Lipid Microbubbles. Pharm Res-Dordr. 29 (5), 1295-1307 (2012).
- Gunn, J., Cumberland, D. Stent coatings and local drug delivery – state of the art. Eur Heart J. 20 (23), 1693-1700 (1999).
- Lu, A., Jia, G., Gao, G., Wang, X. The effect of magnetic stent on coronary restenosis after percutaneous transluminal coronary angioplasty in dogs. Chin Med J (Engl. 114 (8), 821-823 (2001).
- Kempe, H., Kempe, M. The use of magnetite nanoparticles for implant-assisted magnetic drug targeting in thrombolytic therapy. Biomaterials. 31 (36), 9499-9510 (2010).
- Chorny, M., et al. Targeting stents with local delivery of paclitaxel-loaded magnetic nanoparticles using uniform fields. P Natl Acad Sci USA. 107 (18), 8346-8351 (2010).
- Polyak, B., Friedman, G. Magnetic targeting for site-specific drug delivery: applications and clinical potential. Expert Opin Drug Del. 6 (1), 53-70 (2009).
- Liu, J. Y., et al. Magnetic stent hyperthermia for esophageal cancer: an in vitro investigation in the ECA-109 cell line. Oncol Rep. 27 (3), 791-797 (2012).
- Gunn, J., Cumberland, D. Does stent design influence restenosis. Eur Heart J. 20 (14), 1009-1013 (1999).
- Aviles, M. O., et al. In vitro study of ferromagnetic stents for implant assisted-magnetic drug targeting. J Magn Magn Mater. 311 (1), 306-311 (2007).
- Mardinoglu, A., et al. Theoretical modelling of physiologically stretched vessel in magnetisable stent assisted magnetic drug targeting application. J Magn Magn Mater. 323 (3-4), 324-329 (2011).
- Liu, Z. Y., et al. Stress corrosion cracking of 2205 duplex stainless steel in H2S-CO2 environment. J Mater Sci. 44 (16), 4228-4234 (2009).
- Alverez-Armas, I., Degallaix-Moreuill, S. . Duplex stainless steels. , (2009).
- Tefft, B. J., et al. Magnetizable Duplex Steel Stents Enable Endothelial Cell Capture. Ieee T Magn. 49 (1), 463-466 (2013).
- Pelton, A. R., et al. Fatigue and durability of Nitinol stents. J Mech Behav Biomed Mater. 1 (2), 153-164 (2008).
- Knowles, M., et al. Finite element analysis of a balloon-expandable stent and superior mesenteric arterial wall interaction. J Vasc Surg. 60 (6), 1722-1723 (2014).
- Veeram Reddy, S. R., et al. A novel biodegradable stent applicable for use in congenital heart disease: bench testing and feasibility results in a rabbit model. Catheter Cardiovasc Interv. 83 (3), 448-456 (2014).
- Shellock, F. G. MR imaging of metallic implants and materials: a compilation of the literature. AJR Am J Roentgenol. 151 (4), 811-814 (1988).
- Lopic, N., et al. Quantitative determination of magnetic force on a coronary stent in MRI. J Magn Reson Imaging. 37 (2), 391-397 (2013).
