A Novel Thin Film Nitinol Covered Stent to Treat Peripheral Arterial Disease

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DESCRIPTION (provided by applicant): This application addresses broad Challenge Area (15) Translational Research and specific Challenge Topic, 15-HL-101: Develop Improved Biocompatible Surfaces for Implantable Blood-Contacting Medical Devices. Peripheral arterial disease (PAD) occurs in 3-10% of the general population and increases to 10-15% in persons over 70 years. Advancements in endovascular therapies for PAD are limited by the lack of a suitable, biocompatible surface for the covering of these blood-contacting devices that lead to thrombosis. The availability of an appropriate, thrombus resistant material for endovascular devices could lead to significant improvements in the over-all mortality and morbidity of PAD. UCLA has developed a unique process that can produce super-hydrophilic and thrombus-resistant thin film Nitinol. It is our hypothesis that this material will be ideally suited for treating PAD without the complications normally associated with current endovascular treatments. We propose to design, fabricate and test a super hydrophilic coated thin film Nitinol (S-TFN) covered stent both in vivo and in vitro for the treatment of PAD. Bulk Nitinol is found in many medical devices including most notably stents. Despite being inert due to its titanium oxide layer, thrombosis occurs due to bulk Nitinol's surface roughness and the overall quality of the titanium oxide layer. Our laboratory has developed a novel patented means to fabricate thin film Nitinol (TFN) using a sputter deposition technique. Surface roughness is two orders of magnitudes smoother when compared to bulk Nitinol and compositional variations less than four times compared to conventional approaches. A novel surface treatment (patent pending) has also been developed to create a super hydrophilic layer which repels negatively charged blood products and prevents thrombosis. The efficacy of this surface to resist thrombosis has been confirmed with recent in vivo and in vitro tests. Platelet adhesion on the S-TFN is significantly reduced compared to commercially available stent coverings such as polytetrafluoroethylene (PTFE). Short term preliminary in vivo swine studies have also demonstrated that S-TFN covered stents support endothelial growth without unwanted neointimal hyperplasia or thrombosis. This proposal builds upon the research already conducted at UCLA on S-TFN to analyze, fabricate, and thoroughly test S-TFN covered stents for treating PAD. The three major components of this proposal are 1) to evaluate S-TFN covered stents for biocompatibility criteria under the ISO standards for indwelling medical devices 2) analyze, design, fabricate, and test a S-TFN covered stent specifically for treating PAD and 3) to finally investigate short, medium, and long term placement of S-TFN covered stents in the peripheral vasculature of a swine model and compare the results to conventional PTFE covered stents. Arterial occlusive disease of the extremities occurs in 3-10% of the population and increases to 10-15% in persons over 70 years. The biggest hurdle for medical devices used in the treatment of this occlusive disease is thrombosis, which is blood clots developing within the implanted device. To solve this problem, UCLA has developed a new surface treatment for thin film Nitinol that in preliminary studies prevents thrombosis and thus is ideally suited for treating occlusive disease of the extremities. PUBLIC HEALTH RELEVANCE: Arterial occlusive disease of the extremities occurs in 3-10% of the population and increases to 10-15% in persons over 70 years. The biggest hurdle for medical devices used in the treatment of this occlusive disease is thrombosis, that is blood clots develop within the implanted device. To solve this problem, UCLA has developed a new surface treatment for thin film Nitinol that in preliminary studies prevents thrombosis and thus is ideally suited for treating occlusive disease of the extremities.