Heart disease is of great societal interest due to its drastic impact on health in industrialized nations, especially in developed countries where obesity rates are high and the typical diet is not conducive to cardiovascular health. While invasive procedures are not desirable, they are often crucial to ensuring patient survival. The 5 million coronary stents administered world-wide each year remain present in the human artery for the lifetime of the patient. This has resulted in the emergence of several serious side effects. A bio absorbable metal stent that harmlessly erodes away over time could minimize the normal chronic risks associated with permanent stents. Mg- and Fe-based alloys currently pursued in designing such biodegradable stents have met with limited success. The research proposed at Michigan Tech aims to develop, for the first time, an alternative line of Zn-based stents that last 6-9 months in vivo. Preliminary study suggests that zinc exhibits ideal physiological corrosion behavior for bio absorbable stent application. The viability of a Zn-Mg stent, the corrosion behavior in vivo, and the degradation rate in the vascular environment remain open questions, and are the subjects of the proposed program. The overall feasibility of bio absorbable Zn-Mg stents will be evaluated. An in vivo evaluation of materials bio corrosion will be completed utilizing a recently developed arterial implantation method in which a sample with wire geometry is implanted into the arterial wall of a rat. Zn-Mg alloys will be prepared in order to tailor the material properties to accepted values of tensile strength, elongation to failure, and penetration rate. Our preliminary study has shown that the magnesium addition to zinc increases the mechanical strength. In addition, electro/chemically active Mg additions will lead to tunable rates of bio corrosion. The research will lead to selection and testing of a Zn-Mg alloy that meets the following criteria: i) keep corrosion rates close to the 0.02 mm/year value; ii) have >200 MPa yield strength, and >20% elongation to failure; and iii) exhibit biocompatibility similar to 316L stainless steel, industria standard for stent materials.
Metal stents are commonly used to keep blood vessels open, but stents can cause long-term complications. Bio absorbable metal stents that harmlessly erode away over time may minimize the normal chronic risks associated with permanent stents. To develop such stents, new zinc- based alloys are proposed and these new bio absorbable metals will be formulated and tested for bio absorbable stent applications.
| Jin, Hualan; Zhao, Shan; Guillory, Roger et al. (2018) Novel high-strength, low-alloys Zn-Mg (<0.1wt% Mg) and their arterial biodegradation. Mater Sci Eng C Mater Biol Appl 84:67-79 |
| Zhao, Shan; Seitz, Jan-M; Eifler, Rainer et al. (2017) Zn-Li alloy after extrusion and drawing: Structural, mechanical characterization, and biodegradation in abdominal aorta of rat. Mater Sci Eng C Mater Biol Appl 76:301-312 |
| Drelich, Adam J; Zhao, Shan; Guillory 2nd, Roger J et al. (2017) Long-term surveillance of zinc implant in murine artery: Surprisingly steady biocorrosion rate. Acta Biomater 58:539-549 |
| Shearier, Emily R; Bowen, Patrick K; He, Weilue et al. (2016) In Vitro Cytotoxicity, Adhesion, and Proliferation of Human Vascular Cells Exposed to Zinc. ACS Biomater Sci Eng 2:634-642 |
| Bowen, Patrick K; Shearier, Emily R; Zhao, Shan et al. (2016) Biodegradable Metals for Cardiovascular Stents: from Clinical Concerns to Recent Zn-Alloys. Adv Healthc Mater 5:1121-40 |
| Bowen, Patrick K; Guillory 2nd, Roger J; Shearier, Emily R et al. (2015) Metallic zinc exhibits optimal biocompatibility for bioabsorbable endovascular stents. Mater Sci Eng C Mater Biol Appl 56:467-72 |
