Comparison of Covered Laser-cut and Braided Respiratory Stents: From Bench to Pre-Clinical Testing
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Lung cancer patients often suffer from severe airway stenosis, the symptoms of which can be relieved by the implantation of stents. Different respiratory stents are commercially available, but the impact of their mechanical performance on tissue responses is not well understood. Two novel laser-cut and hand-braided nitinol stents, partially covered with polycarbonate urethane, were bench tested and implanted in Rhön sheep for 6 weeks. Bench testing highlighted differences in mechanical behavior: the laser-cut stent showed little foreshortening when crimped to a target diameter of 7.5 mm, whereas the braided stent elongated by more than 50%. Testing also revealed that the laser-cut stent generally exerted higher radial resistive and chronic outward forces than the braided stent, but the latter produced significantly higher radial resistive forces at diameters below 9 mm. No migration was observed for either stent type in vivo. In terms of granulation, most stents exerted a low to medium tissue response with only minimal formation of granulation tissue. We have developed a mechanical and in vivo framework to compare the behavior of different stent designs in a large animal model, providing data, which may be employed to improve current stent designs and to achieve better treatment options for lung cancer patients.
KeywordsStent development Airway stenting Animal trial Sheep model Nitinol stent
The authors thank the Institute of Laboratory Animal Science (RWTH Aachen University Hospital) headed by Prof. Dr. René H. Tolba, especially Dr. Kira Scherer, Lisa Liebenstund, Dunja Sieger and Thaddäus Stopinski, as well as Irina Appel (BioTex) for technical help in thin section cutting. We thank Dr. Richard M. Twyman for manuscript editing. This work was financially supported by the European Union Seventh Framework Program (FP7/2007-2013 under grant agreement number NMP3-SL-2012-280915). Funding from the College of Engineering and Informatics at NUI Galway through a College Scholarship is also acknowledged, along with funding support provided by the Structured Ph.D. Program in Biomedical Engineering and Regenerative Medicine (BMERM). Funded under the Program for Research in Third-Level Institutions (PRTLI) Cycle 5 (Strand 2) and co-funded under the European Regional Development Fund (ERDF).
Conflict of interest
No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
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