A pilot study of a novel biodegradable magnesium alloy airway stent in a rabbit model.

OBJECTIVE: To preliminarily investigate the feasibility of bioabsorption tracheal stenting for the therapeutic application of congenital tracheal stenosis (CTS).

STUDY DESIGN: Experimental research.

SETTING: Shanghai Children Medical Center, National Children's Medical Center.

SUBJECTS AND METHODS: Five kinds of magnesium alloys with different compositions were studied in this paper, a patented Mg-Nd-Zn-Zr alloy series namely JDBM (JiaoDa BioMg) and four Mg-Ca-Zn alloys. The cytotoxicity of alloys was evaluated by the MTS ([3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay in rabbit tracheal epithelial cells. Specific magnesium alloys had been immersed in the cell culture medium for 24 h. The tracheal stents that were made of magnesium alloy were implanted into the trachea of New Zealand rabbits and the ablation of the stent was monitored by fiber bronchoscopy. The routine blood examination was conducted prior to and following the stent placement. The rabbits were euthanized following 2-3 months of stenting. H&E staining of the main organs was conducted and the induction of apoptosis of the tracheal tissues was monitored.

RESULTS: The cytotoxicity of the JDBM magnesium alloy was mild and lower than the remaining 4 alloys. The stents were placed successfully in five animals. The tracheal stents were successfully placed and gradually biodegradated as monitored by fiber bronchoscopy; no significant systemic inflammatory response was noted. No significant differences in the liver and/or kidney function prior to and following stent placement were noted. H&E staining indicated the absence of pathological changes in the trachea, liver, heart and/or kidney tissues. The apoptotic assay indicated that the apoptosis ratio of the tracheal tissues was comparable between rabbits with and without tracheal stenting.

CONCLUSION: The results suggested the feasibility of bioabsorption stents made of biodegradable magnesium alloys using in patients with tracheal stenosis, especially in infants.