Improving biliary stent patency by the use of stent coating – a prospective randomized porcine study

Abstract

Background: Endoscopic stenting of the bile duct is a standard procedure for almost 35 years. In the case of long-term stenting occlusion of the stent is a major concern. Therefore optimizing biliary stents with respect to their patency is of great importance. We tested in an in animal study if coating of self-expanding metal stents with hydrophobin alone or hydrophobin with heparin reduces stent clogging as there were promising results in an in vitro study with this approach.

Material and methods: In a randomized prospective animal study we implanted self-expanding metal stents either native or coated with hydrophobin alone or coated with hydrophobin and heparin into the bile duct of 15 pigs. After a survival period of 6 weeks we measured which part of the stent surface (%) was covered with clogging material using a commercially available image editing program on scanning electron microscopic images.

Results: We found no differences between the native self-expanding metals stents and those coated with hydrophobin alone or hydrophobin and heparin.

Conclusion: There are important differences in the clogging process between in vitro and in vivo models. Coating with hydrophobin with or without heparin is not able to inhibit the clogging process in an animal model.

Zusammenfassung

Hintergrund: Die endoskopische Stentimplantation in den Gallengang ist seit mittlerweile 35 Jahren ein Routineeingriff. Bei längerer Liegedauer eines Gallengangsstents stellt der langfristig unvermeidliche Stentverschluss ein Problem dar. Daher ist die Verbesserung der Offenheitsdauer von Gallengangsstents ein wichtiges Ziel. Aufgrund vielversprechender Ergebnisse in einer In-vitro-Studie überprüften wir in einer Tierstudie, ob ein Beschichten von selbstexpandierenden Metallstents mit Hydrophobin oder mit einer Kombination aus Hydrophobin und Heparin die Offenheitsdauer verbessern kann.

Methoden: In einer randomisierten prospektiven Tierstudie implantierten wir in jeweils 5 Schweine native oder mit Hydrophobin beschichtete oder mit einer Kombination aus Hydrophobin und Heparin beschichtete selbstexpandierende Metallstents. Nach einer Überlebensphase von 6 Wochen führten wir eine Nekropsie durch und erfassten den Anteil der Stentoberfläche (%), der von angelagertem Verschlussmaterial bedeckt war. Die Messung erfolgte mit einer kommerziell erhältlichen Bildverarbeitungssoftware an rasterelektronischen Bildern der Stentoberfläche.

Ergebnisse: Wir fanden keinen Unterschied in dem Anteil der Oberfläche der selbstexpandierenden Metallstents, der frei von Verschlussmaterial war, zwischen den unbeschichteten und den beschichteten selbstexpandierenden Metallstents.

Schlussfolgerung: Das Beschichten von selbstexpandierenden Metallstents mit Hydrophobin oder einer Kombination aus Hydrophobin und Heparin führt im Schweinemodell nicht zu einer Reduktion von an der Stentoberfläche nachweisbarem Verschlussmaterial. Der Verschlussprozess von Gallengangsstents in einem In-vitro-Modell unterscheidet sich von dem in einem In-vivo-Modell.

Schlüsselwörter

Gallengangsstents - Nanotechnologie - Rasterelektronenmikroskopie

Key words

biliary stents - nanotechnology - scanning electron microscopy

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