Dec 10, 2015 - Abstract: Since the introduction of various endovascular graft materials such as expanded polytetrafluoroethylene (e-PTFE) and DacronV. R.
A novel low-profile thin-film nitinol/silk endograft for treating small vascular diseases Mahdis Shayan,1 Sungyeun Yang,2 WonHyoung Ryu,2 Youngjae Chun1,3 1
Department of Industrial Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania Department of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea 3 Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania 2
Received 3 May 2015; revised 20 September 2015; accepted 27 September 2015 Published online 00 Month 2015 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/jbm.b.33548 Abstract: Since the introduction of various endovascular graft materials such as expanded polytetrafluoroethylene (e-PTFE) and DacronV polyester, they have been rapidly applied in endovascular devices for treating a variety of clinical situations. While present endovascular grafts have been successful in treating large blood vessels, there are still significant challenges and limitations for small and tortuous vessels to their use. Recently, our group has demonstrated the potential to use thin-film nitinol (TFN) as a novel material to develop endografts used in the treatment of a wide range of small vascular diseases because TFN is ultralow profile (that is, a few micrometers thick), relatively thromboresistant, and superelastic. While TFN has shown superior thromboresistance, its surface endothelialization is not rapid and sufficient. R
Therefore, our laboratory has been exploring the feasibility of using thin-film silk as a novel coating for facilitating rapid and confluent endothelial cell growth. The purpose of this study is to fabricate a low-profile composite endograft using thin layers of nitinol and silk, and to evaluate both thrombogenicity as well as endothelial cell and smooth muscle cell responses. This study also evaluates the functionality of the composite endograft using an in vitro blood circulation C 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: model. V Appl Biomater 00B: 000–000, 2015.
Key Words: thin-film nitinol, silk fibroin, electrospinning, endovascular graft
How to cite this article: Shayan M, Yang S, Ryu WH, Chun Y. 2015. A novel low-profile thin-film nitinol/silk endograft for treating small vascular diseases. J Biomed Mater Res Part B 2015:00B:000–000.
INTRODUCTION
Transcatheter endovascular therapy has made a significant progress in treating occlusive vascular diseases via presenting various minimally invasive devices. However, when these devices are used to treat small vascular diseases—e.g., pediatric cardiovascular diseases, vascular wall erosion with subsequent immobilization, and small artery aneurysms— there still remains critical risks in terms of the device delivery, restenosis occurrence, and hemocompatibility.1,2 As an example, coarctation of the aorta (CoA) is a narrowing occurrence in a short segment of aorta, where the main artery distributes the oxygenated blood from the left ventricle to all parts of body. It is a relatively common defect that accounts for 5–8% of all congenital heart defects.3 If CoA is not diagnosed and treated in a timely manner, it is developed into the congestive heart failure (CHF) or hypertensions which both are among common pediatrics cardiovascular diseases. Open surgery (that is, eliminating the narrowed section and connecting ends of the arteries along with using medication) is a common method to treat
newborns diagnosed with CoA. Alternative treatment options specifically applied for older children are transcatheter-based therapies that include a dilation of the narrowed site using an angioplasty balloon or the placement of a vascular stent in the narrowed site.4–7 While both surgical and transcatheter-based procedures are widely used for treating CoA, there are a few potential complications such as possible damages to the downstream organs such as kidney because of the blood flow interruption during surgery, CoA recurrence after balloon dilation due to the vessel damages, and restenosis occurrence at the narrowed site especially after stent deployment. In addition, systematic hypertension, aortic valve abnormalities, and aortic aneurysm formation could be other concerns that can occur after the conventional CoA treatments.3,8,9 All these complications are driving force to seek for a safer and more effective treatment method for CoA treatment. The ideal device for treatment of CoA could be a low-profile endovascular device, which can (1) be safely delivered with a micro delivery catheter (e.g.,
