Self-expandable chitosan stent: design and preparation.

Stents are largely used in surgical procedures to relieve pathological obstructions. The purpose of the present study was to design and prepare a biocompatible stent with a self-expandable mechanism. Thin films were prepared from deacetylated chitosan (4% w/v) dissolved in acetic acid solution (2% v/v). The chitosan films were tested by a calibrated tensiometer to measure the Young's module (E). The films were used to manufacture stents by pulling and winding them around a cylindrical rod in a helical fashion. Thirteen stents (diameter = 0.5 +/- 0.05 mm, length approximately 4 mm) were inserted into the vas deferens of wistar rats. Upon stent insertion, the vasal anastomosis was achieved with a laser-soldering technique. The animals were sacrificied 8 weeks later. The stress test showed that the chitosan film was elastic (maximum strain = 105% +/- 6%, E = 0.7655 +/- 0.0288 Mpa). The stents self-expanded by releasing their elastic energy. All the stents but one remained open inside the vasa despite high incidence of sperm granuloma. A biocompatible and self-expandable stent with a helical design is proposed.