A comparative study of in vitro biocompatibility of Zn and AZ31 for cardiovascular stent application

摘要

Introduction: Biodegradable metals including magnesium (Mg)-, zinc (Zn)-, and iron (Fe)-based alloys have been widely developed and investigated for biomedical applications. However, the main drawbacks of Mg are low corrosion resistance and insufficient mechanical strength. For Fe-based alloys, the main problem is the slow corrosion, thus causing the similar biological reactions compared to permanent implants. In a rat model, zinc exhibits almost ideal corrosion behavior. A slow corrosion occurred within the first 4 months, and from 4.5 months to 6 months, an accelerated corrosion was observed . Few study compared the in vitro biocompatibility and hemocompatibility of Zn and Mg-based alloys for cardiovascular stent application. Therefore, in this study, we comprehensively evaluated the in vitro biocompatibility and hemocompatibility of Zn and Mg alloy AZ31. Materials and Methods: For cell viability and proliferation, cells were cultured with Zn and AZ31 extract solutions for 1,3, and 5 days respectively. Cell migration was evaluted by a scratch test. Cell migration rate was determined by the changes in the width of the scratch. In vitro endothelialization test were conducted by seeding cells on the top of Zn and AZ31 directly. At 1 day and 3 days, cells were stained by calcein AM and images were taken. Electrochemical test and immersion test were used to characterize the corrosion resistance of Zn and AZ31. Hemocompatibility was determined by platelet adhesion test and hemolysis test. Results and Discussion: Cell viability, cell proliferation and cell migration were in extract concentration-dependent manner. Low concentration extracts had no adverse influence on cell viability, proliferation and cell migration. In contrast, high extract concentrations significantly inhibit cell viability, proliferation and cell migration. In in vitro endothelialization test, more endothelial cells were observed on Zn surface, while almost no cells were observed on AZ31 surface. Zn had a significantly lower corrosion rate, compared to AZ31. A significantly lower number of platelets adhered to Zn compared to AZ31. The hemolysis ratio of Zn was also significantly lower than that of AZ31. Conclusion: Zn had much higher corrosion resistance and better biocompatibility and hemocompatiblity, compared to AZ31. Therefore, Zn is a promising candidate biomaterial for cardiovascular stent application.