Drug-eluting fully covered self-expanding metal stent for dissolution of bile duct stones in vitro.

BACKGROUND

The treatment of difficult common bile duct stones (CBDS) remains a big challenge around the world. Biliary stenting is a widely accepted rescue method in patients with failed stone extraction under endoscopic retrograde cholangiopancreatography. Fully covered self-expanding metal stent (FCSEMS) has gained increasing attention in the management of difficult CBDS.

AIM: To manufacture a drug-eluting FCSEMS, which can achieve controlled release of stone-dissolving agents and speed up the dissolution of CBDS.

METHODS

Customized covered nitinol stents were adopted. Sodium cholate (SC) and disodium ethylene diamine tetraacetic acid (EDTA disodium, EDTA for short) were used as stone-dissolving agents. Three different types of drug-eluting stents were manufactured by dip coating (Stent I), coaxial electrospinning (Stent II), and dip coating combined with electrospinning (Stent III), respectively. The drug-release behavior and stone-dissolving efficacy of these stents were evaluated in vitro to sort out the best manufacturing method. And the selected stone-dissolving stents were further put into porcine CBD to evaluate their biosecurity.

RESULTS

Stent I and Stent II had obvious burst release of drugs in the first 5 d while Stent III presented controlled and sustainable drug release for 30 d. In still buffer, the final stone mass-loss rate of each group was 5.19% ± 0.69% for naked FCSEMS, 20.37% ± 2.13% for Stent I, 24.57% ± 1.45% for Stent II, and 33.72% ± 0.67% for Stent III. In flowing bile, the final stone mass-loss rate of each group was 5.87% ± 0.25% for naked FCSEMS, 6.36% ± 0.48% for Stent I, 6.38% ± 0.37% for Stent II, and 8.15% ± 0.27% for Stent III. Stent III caused the most stone mass-loss no matter in still buffer or in flowing bile, which was significantly higher than those of other groups (P < 0.05). In vivo, Stent III made no difference from naked FCSEMS in serological analysis (P > 0.05) and histopathological examination (P > 0.05).

CONCLUSION

The novel SC and EDTA-eluting FCSEMS is efficient in diminishing CBDS in vitro. When conventional endoscopic techniques fail to remove difficult CBDS, SC and EDTA-eluting FCSEMS implantation may be considered a promising alternative.