Safety and efficacy of bioabsorbable magnesium alloy stents in porcine coronary arteries

Waksman, Ron; Pakala, Rajbabu; Kuchulakanti, Pramod K.; Baffour, Richard; Hellinga, David; Seabron, Rufus; Tio, Fermin O.; Wittchow, Eric; Hartwig, Sonja; Harder, Claus; Rohde, R.; Heublein, B; Andreae, Arnim; Waldmann, Karl-Heinz; Haverich, Axel

doi:10.1002/ccd.20727

Cited by 296 publications

(211 citation statements)

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“…These alloys have recently been tested intensively in clinical trials for their potential as biodegradable implants. 13,15,18 But their use is limited by their rapid degradation leading to the accumulation of degradation products in the vessel wall leading to medial swelling, neointimal proliferation, and ex-stent restenosis. Therefore, they can be compared only inferiorly both to bare metal or drug eluting stents.…”

Section: Discussionmentioning

confidence: 99%

“…Uncoated pure magnesium or magnesium based alloys exhibited ex stent restenosis and medial disruption leading to local adverse effects. 18 Adverse effects after stent implantation are most likely related to rapid degradation kinetics. 19 Fluoride coating has been shown to delay the degradation process; however, corrosion still occurs at undesirably rapid rates.…”

Section: Introductionmentioning

confidence: 99%

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In vitroandin vivocorrosion properties of new iron–manganese alloys designed for cardiovascular applications

et al. 2014

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The principle of biodegradation for the production of temporary implant materials (e.g. stents) plays an important role in the treatment of congenital heart defects. In the last decade several attempts have been made with different alloy materials—mainly based on iron and magnesium. None of the currently available materials in this field have demonstrated satisfying results and have therefore not found entry into broad clinical practice. While magnesium or magnesium alloy systems corrode too fast, the corrosion rate of pure iron‐stents is too slow for cardiovascular applications. In the last years FeMn alloy systems were developed with the idea that galvanic effects, caused by different electrochemical properties of Fe and Mn, would increase the corrosion rate. In vitro tests with alloys containing up to 30% Mn showed promising results in terms of biocompatibility. This study deals with the development of new FeMn alloy systems with lower Mn concentrations (FeMn 0.5 wt %, FeMn 2.7 wt %, FeMn 6.9 wt %) to avoid Mn toxicity. Our results show, that these alloys exhibit good mechanical features as well as suitable in vitro biocompatibility and corrosion properties. In contrast, the evaluation of these alloys in a mouse model led to unexpected results—even after 9 months no significant corrosion was detectable. Preliminary SEM investigations showed that passivation layers (FeMn phosphates) might be the reason for corrosion resistance. If this can be proved in further experiments, strategies to prevent or dissolve those layers need to be developed to expedite the in vivo corrosion of FeMn alloys. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 649–660, 2015.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

In vitroandin vivocorrosion properties of new iron–manganese alloys designed for cardiovascular applications

et al. 2014

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“…Basically, magnesium-and iron-based alloys are two classes of metals which have been proposed. Among Mg-based alloys have been studied, include MgAl- (Heublein, 2003, Witte, 2005, Xin, 2007), MgRE-(Di Mario, 2004, Peeters, 2005, Witte, 2005, Waksman, 2006, Hänzi, 2009) and MgCa- (Zhang, 2008, Li, 2008 based alloys. Meanwhile, for Fe-based alloys, pure iron (Peuster, 2001, Peuster, 2006 and FeMn alloys (Hermawan, 2008, Schinhammer, 2009) have been investigated mainly for cardiovascular applications.…”

Section: Biodegradable Metalsmentioning

confidence: 99%

Metals for Biomedical Applications

Hermawan¹,

Ramdan²,

Djuansjah³

2011

Biomedical Engineering - From Theory to Applications

157

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Biomedical Engineering -From Theory to Applications 412 visible under X-ray imaging. Most of artificial implants are subjected to loads, either static or repetitive, and this condition requires an excellent combination of strength and ductility. This is the superior characteristic of metals over polymers and ceramics. Specific requirements of metals depend on the specific implant applications. Stents and stent grafts are implanted to open stenotic blood vessels; therefore, it requires plasticity for expansion and rigidity to maintain dilatation. For orthopaedic implants, metals are required to have excellent toughness, elasticity, rigidity, strength and resistance to fracture. For total joint replacement, metals are needed to be wear resistance; therefore debris formation from friction can be avoided. Dental restoration requires strong and rigid metals and even the shape memory effect for better results. In overall, the use of biomaterials in clinical practice should be approved by an authoritative body such as the FDA (United States Food and Drug Administration). The proposed biomaterial will be either granted Premarket Approval (PMA) if substantially equivalent to o n e u s e d b e f o r e F D A l e g i s l a t i o n o f 1 9 7 6 , o r h a s t o g o t h r o u g h a s e r i e s o f g u i d e d biocompatibility assessment. Common metals used for biomedical devicesUp to now, the three most used metals for implants are stainless steel, CoCr alloys and Ti alloys. The first stainless steel used for implants contains ~18wt% Cr and ~8wt% Ni makes it stronger than the steel and more resistant to corrosion. Further addition of molybdenum (Mo) has improved its corrosion resistance, known as type 316 stainless steel. Afterwards, the carbon (C) content has been reduced from 0.08 to 0.03 wt% which improved its corrosion resistance to chloride solution, and named as 316L. Titanium is featured by its light weight. Its density is only 4.5g/cm 3 compared to 7.9g/cm 3 for 316 stainless steel and 8.3g/cm 3 for cast CoCrMo alloys (Brandes and Brook, 1992). Ti and its alloys, i.e. Ti6Al4V are known for their excellent tensile strength and pitting corrosion resistance. Titanium alloyed with Ni, i.e. Nitinol, forms alloys having shape memory effect which makes them suitable in various applications such as dental restoration wiring. In dentistry, precious metals and alloys often used are Au, Ag, Pt and their alloys. They possess good castability, ductility and resistance to corrosion. Included into dental alloys are AuAgCu system, AuAgCu with the addition of Zn and Sn known as dental solder, and AuPtPd system used for porcelain-fused-to-metal for teeth repairs. CoCr alloys have been utilised for many decades in making artificial joints. They are generally known for their excellent wear resistance. Especially the wrought CoNiCrMo alloy has been used for making heavily loaded joints such as ankle implants (Figure 1). Other metals used for implants include tantalum (Ta), amorphous alloys and biodegradable metals. Tantalum which has excell...

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“…Several materials have been reported as potential degradable metallic materials (DMMs) for cardiovascular stent application including pure iron [4], Fe-35Mn alloy [5], magnesium alloy [6][7], and others. For cardiovascular stent application, iron based materials present suitable ductility compared to that of magnesium-based materials.…”

Section: Introductionmentioning

confidence: 99%

Gene expression profile of mouse fibroblasts exposed to a biodegradable iron alloy for stents

et al. 2013

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Iron based materials could constitute an interesting option for cardiovascular biodegradable stent applications due to their superior ductility compared to their counterparts-magnesium alloys. Since the predicted degradation rate of pure iron is considered slow, manganese (35% w/w), an alloying element for iron, was explored to counteract this problem through the powder metallurgy process . However, manganese presents a high cytotoxic potential, thus its effect on cells must first be established. Here, we explored a new method to investigate a degradable metallic material (DMM) by establishing the gene expression profile (GEP) of mouse 3T3 fibroblasts exposed to Fe-35Mn degradation products in order to better understand cell response to potentially cytotoxic DMM. Briefly, 3T3 cells were exposed to degradation products eluting through tissue culture insert filter (3 µm pore size) containing cytostatic amounts of 3.25 mg/ml of Fe-35Mn powder, 0,25 mg/ml of pure Mn powder or 5 mg/ml of pure iron powder for 24 hours. We then conducted a gene expression profiling study from these cells. Exposure of 3T3 cells to Fe-35Mn was associated with the up-regulation of 75 genes and down-regulation of 59 genes, while 126 were up-regulated and 76 down-regulated genes in presence of manganese. No genes were found regulated for the iron powder. When comparing the GEP of 3T3 fibroblasts in presence of Fe-35Mn and Mn, 68 up-regulated and 54 down-regulated genes were common. These results were confirmed by quantitative RT-PCR for a subset of these genes. This GEP study could provide clues about the mechanism behind degradation products effects on cells of the Fe-35Mn alloy and may help in the appraisal of its potential for DMM applications.

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Safety and efficacy of bioabsorbable magnesium alloy stents in porcine coronary arteries

Abstract: Magnesium alloy stents are safe and are associated with less neointima formation; however, reduced neointima did not result in larger lumen.

Cited by 296 publications

References 17 publications

In vitroandin vivocorrosion properties of new iron–manganese alloys designed for cardiovascular applications

In vitroandin vivocorrosion properties of new iron–manganese alloys designed for cardiovascular applications

Metals for Biomedical Applications

Gene expression profile of mouse fibroblasts exposed to a biodegradable iron alloy for stents

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