A fully covered self-expandable metallic stent coated with poly (2-methoxyethyl acrylate) and its derivative: In vitro evaluation of early-stage biliary sludge formation inhibition.

The adhesion and deformation behavior of proteins at the inner surface of fully covered, self-expandable metallic stents coated with biocompatible polymers, poly(2-methoxyethyl acrylate) (PMEA) and poly(3-methoxypropyl acrylate) (PMC3A), were analyzed. Model bile solution, proteins, and bacteria were used to unravel the inhibitory ability of the polymer coatings. Adsorbance of proteins and adherence of bacteria were both strongly inhibited by the polymer coatings. Circulation tests were performed under clinical conditions using human bile from patients. Adsorption/deformation of proteins and early-stage sludge formation were inhibited on stent surfaces coated with PMEA derivatives. The present study revealed that early-stage biliary sludge formation on PMEA- and PMC3A-coated stents was suppressed due to the strong resistance of the polymers to protein adsorption/deformation, brought about by intermediate water in hydrated polymer coatings, which is not present in conventional coating materials, such as silicone and polyurethane.