Rates ofin vivo(arterial) andin vitrobiocorrosion for pure magnesium

Abstract

The development of magnesium-based materials for bioabsorbable stents relies heavily on corrosion testing by immersion in pseudophysiological solutions, where magnesium degrades faster than it does in vivo. The quantitative difference in corrosion kinetics in vitro and in vivo is largely unknown, but, if determined, would help reduce dependence on animal models. In order to create a quantitative in vitro-in vivo correlation based on an accepted measure of corrosion (penetration rate), commercially pure magnesium wires were corroded in vivo in the abdominal aortas of rats for 5232 days, and in vitro for up to 14 days using Dulbecco's modified eagle medium. Cross-sectioning, scanning electron microscopy, image analysis, a modified penetration rate tailored to degraded wires, and empirical modeling were used to analyze the corroded specimens. In vitro penetration rates were consistently higher than comparable in vivo rates by a factor of 1.221.93 (60.23). For a sample <20% corroded, an approximate in vitro-in vivo multiplier of 1.3 6 0.23 was applied, whereas a multiplier of 1.8 6 0.23 became appropriate when the magnesium specimen was 25235% degraded.

Metallic zinc exhibits optimal biocompatibility for bioabsorbable endovascular stents

“…In an effort to reduce the considerable obstacles present in the developmental path of new metallic materials, we have recently developed a simplified approach for evaluating candidate stent materials in vivo [24, 25, 29–31]. In this model, a wire of the selected material (simulating an individual stent strut) is implanted into the rat abdominal aorta.…”

“…In this model, a wire of the selected material (simulating an individual stent strut) is implanted into the rat abdominal aorta. With this approach, we have shown that magnesium corrodes too rapidly to be used as the base material for a stent without first undergoing considerable metallurgical modification to safely reduce the corrosion rate [24]. Similarly, we have demonstrated that iron undergoes a harmful mode of corrosion, as it produces a voluminous iron oxide that repels neighboring cells and matrix [29].…”

Building towards a standardised approach to biocorrosion studies: a review of factors influencing Mg corrosion in vitro pertinent to in vivo corrosion

“…For larger animal studies sheep [122] and pigs [123] have been used previously, with dogs and goats also established in the field [119]. In cardiovascular applications rats are also used as a small animal model [124][125][126], with pigs generally favoured once large animal trials are required [127].…”

“…However, there are some few studies which have enough similarities to justify a direct comparison. Two such studies are in Table 9 [126,129]. These studies considered CP-Mg wire in both an orthopaedics and cardiovascular location, and while the time points of analysis were not identical, they were comparable.…”

Bioeffects of micron‐size magnesium particles on inflammatory cells and bone turnover in vivo and in vitro

“…Among the biodegradable materials, Mg is unique because of its activity in body fluids. 20 In this study, to understand how MgMPs derived from Mg corrosion interact with inflammatory cells and the implant environment, we investigated the effects of MgMps in vitro and in vivo on the inflammatory response and the ultimate effect on bone structure. Titanium particles (TiMPs) were used as a metallic material control.…”