Bare-metal stents (BMS) and drug-eluting stents (DES) are the two main categories of FDA-approved coronary stents in the market for treating atherosclerosis. Problems associated with BMS include in-stent restenosis due to intimal hyperplasia, leading to stent failure, while DES harbours a life-threatening complication called late-stent thrombosis due to drug-polymer hypersensitivity and impaired re-endothelialization. One approach to overcoming the above-mentioned problems could be using covered stents. Covered stents have an additional layer of membrane spanning the stent struts, and can be considered hybrid stent-grafts. Due to the added protection that the membrane affords, covered stents are currently used for vessel perforations and aneurysms. They can act as a physical barrier to inhibit smooth muscle cell in-growth and intimal hyperplasia formation. The most commonly used membrane for covered stents is expanded polytetrafluoethylene (ePTFE). However, its non-compliant and thrombogenic nature prevents it from being suitable for use in small-diameter vessels, resulting in an unmet clinical need for a haemocompatible covered stent for this application. A polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) nanocomposite polymer was developed by our group, and has already been used in three first-in-man studies as a bypass graft, lacrimal duct, and the world’s first synthetic trachea. Hence we sought to assess the feasibility of using POSS-PCU as a membrane for covered stents. Results indicate that POSS-PCU was haemocompatible, and was able to support the growth and proliferation of endothelial cells, compared to controls. Mechanical tests on membranes revealed that POSS-PCU was superior to ePTFE. Furthermore, it was also found that integration of POSS-PCU membrane onto stents did not adversely affect stent mechanics. In summary, the overall biomechanical performance of POSS-PCU indicates that it has the potential to function as a viable membrane material for covered stents in small diameter vessels.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:626496 |
| Date | January 2013 |
| Creators | Farhatnia, Y. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1416832/ |
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