In vitro degradation and biocompatibility evaluation of typical biodegradable metals (Mg/Zn/Fe) for the application of tracheobronchial stenosis

Tracheobronchial obstruction in children due to benign stenosis or tracheobronchomalacia still remains a challenging matter of concern. Currently, there is 10%–20% complication rate in clinical treatment. The non-biodegradable property of silicone stents and nickel-titanium memory alloy stents take the primary responsibility for drawbacks including stimulating local granulation tissue proliferation, displacement, and stent-related infections. Permanent tracheobronchial stent will be a persistent foreign object for a long time, causing excessive secretion of tracheal mucosa, ulceration and even perforation, which is particularly unsuitable for young children with persistent tracheal growth. In this study, the degradation and biocompatibility performance of three typical biodegradable metals were investigated as potential tracheobronchial stent materials. The results exhibited that these materials showed different degradation behaviors in the simulating respiratory fluid environment compared with SBF. Except for pure iron group, high purity magnesium and zinc showed favorable cell adhesion and proliferation in three culture methodologies (direct culture, indirect culture and extraction culture). The proper corrosion rate and good biocompatibility indicated that high purity magnesium and zinc may be good candidates as tracheobronchial stent materials.