Drelich Adam J, Zhao Shan, Guillory Roger J, Drelich Jaroslaw W, Goldman Jeremy
Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931, USA.
Department of Material Science and Engineering, Michigan Technological University, Houghton, MI 49931, USA.
Acta Biomater. 2017 Aug;58:539-549. doi: 10.1016/j.actbio.2017.05.045. Epub 2017 May 19.
Metallic zinc implanted into the abdominal aorta of rats out to 6months has been demonstrated to degrade while avoiding responses commonly associated with the restenosis of vascular implants. However, major questions remain regarding whether a zinc implant would ultimately passivate through the production of stable corrosion products or via a cell mediated fibrous encapsulation process that prevents the diffusion of critical reactants and products at the metal surface. Here, we have conducted clinically relevant long term in vivo studies in order to characterize late stage zinc implant biocorrosion behavior and products to address these critical questions. We found that zinc wires implanted in the murine artery exhibit steady corrosion without local toxicity for up to at least 20months post-implantation, despite a steady buildup of passivating corrosion products and intense fibrous encapsulation of the wire. Although fibrous encapsulation was not able to prevent continued implant corrosion, it may be related to the reduced chronic inflammation observed between 10 and 20months post-implantation. X-ray elemental and infrared spectroscopy analyses confirmed zinc oxide, zinc carbonate, and zinc phosphate as the main components of corrosion products surrounding the Zn implant. These products coincide with stable phases concluded from Pourbaix diagrams of a physiological solution and in vitro electrochemical impedance tests. The results support earlier predictions that zinc stents could become successfully bio-integrated into the arterial environment and safely degrade within a time frame of approximately 1-2years.
Previous studies have shown zinc to be a promising candidate material for bioresorbable endovascular stenting applications. An outstanding question, however, is whether a zinc implant would ultimately passivate through the production of stable corrosion products or via a cell mediated tissue encapsulation process that prevented the diffusion of critical reactants and products at the metal surface. We found that zinc wires implanted in the murine artery exhibit steady corrosion for up to at least 20months post-implantation. The results confirm earlier predictions that zinc stents could safely degrade within a time frame of approximately 1-2years.
已证明植入大鼠腹主动脉长达6个月的金属锌会降解，同时避免出现通常与血管植入物再狭窄相关的反应。然而，关于锌植入物最终是否会通过产生稳定的腐蚀产物或通过细胞介导的纤维包裹过程（该过程可防止关键反应物和产物在金属表面扩散）而钝化，仍存在重大疑问。在此，我们进行了具有临床相关性的长期体内研究，以表征锌植入物后期的生物腐蚀行为和产物，从而解决这些关键问题。我们发现，植入小鼠动脉的锌丝在植入后至少20个月内表现出稳定的腐蚀且无局部毒性，尽管钝化腐蚀产物不断积累且锌丝被强烈的纤维包裹。虽然纤维包裹无法阻止植入物的持续腐蚀，但它可能与植入后10至20个月期间观察到的慢性炎症减轻有关。X射线元素分析和红外光谱分析证实氧化锌、碳酸锌和磷酸锌是锌植入物周围腐蚀产物的主要成分。这些产物与生理溶液的Pourbaix图和体外电化学阻抗测试得出的稳定相一致。结果支持了早期的预测，即锌支架可以成功地生物整合到动脉环境中，并在大约1至2年的时间内安全降解。
先前的研究表明，锌是生物可吸收血管内支架应用中一种有前景的候选材料。然而，一个突出的问题是，锌植入物最终是否会通过产生稳定的腐蚀产物或通过细胞介导的组织包裹过程（该过程可防止关键反应物和产物在金属表面扩散）而钝化。我们发现，植入小鼠动脉的锌丝在植入后至少20个月内表现出稳定腐蚀。结果证实了早期的预测，即锌支架可以在大约1至2年的时间内安全降解。
