Self expandable metallic stents (SEMS) are effective in the palliation of malignant airway obstruction. Tumor in-growth, however, frequently occurs because of a shortage of effective local therapy. Additionally, SEMS are frequently associated with problems of fracture, migration, and difficult removals. Our goal was to develop a novel bioabsorbable stent with cisplatin elution to circumvent such problems.
Biodegradable stents made of polycaprolactone were fabricated by a laboratory-made, micro-injection molding machine. In vitro mechanical strength of the stents was compared to the strength of ultraflex SEMS. Polylactide-polyglycolide copolymer and cisplatin were coated onto the surfaces of the stents. Elution method and high performance liquid chromatography (HPLC) analysis were utilized to examine the in vitro cisplatin release characteristics. In vivo, the stents were surgically implanted into the cervical trachea of 15 New Zealand white rabbits. Bronchoscopic examination was performed weekly (1∼5 weeks) before euthanasia. Cisplatin concentrations in trachea, lung, and blood were analyzed by HPLC. Histological examination was also performed.
The biodegradable stent exhibited mechanical strength comparable to the strength of ultraflex SEMS and provided a steady release of cisplatin for more than 4 weeks in vitro. The in vivo study showed sustained cisplatin levels in rabbit trachea for more than 5 weeks with a minimum drug level in blood. Histological examination showed an intact ciliated epithelium and marked leukocyte infiltration in the submucosa of the stented area.
Our study demonstrated that the biodegradable stents provided physical properties comparable to the properties of SEMs and a sustained release of cisplatin for more than 5 weeks, which showed great potential in the treatment of malignant airway obstruction.