title: Super hydrophilic thin film nitinol demonstrates reduced platelet adhesion compared with commercially available endograft materials.
abstract: BACKGROUND
  Thin film nitinol (TFN) is a novel material with which to cover stents for the treatment of a wide range of vascular disease processes. This study aimed to show that TFN, if treated to produce a super hydrophilic surface, significantly reduces platelet adhesion, potentially rendering covered stents more resistant to thrombosis compared to commercially available materials.
  
  
  METHODS
  TFN was fabricated using a sputter deposition process to produce a 5-μ thin film of uniform thickness. TFN then underwent a surface treatment process to create a super hydrophilic layer. Platelet adhesion studies compared surface treated TFN (S-TFN) to untreated TFN, polytetrafluoroethylene, Dacron, and bulk nitinol. In vivo swine studies examined the placement of an S-TFN covered stent in a 3.5 mm diameter external iliac artery. Angiography confirmed placement, and repeat angiography was performed at 2 wk followed by post mortem histopathology.
  
  
  RESULTS
  S-TFN significantly reduced platelet adhesion without any evidence of aggregation compared with all materials studied (P < 0.05). Furthermore, in vivo swine studies demonstrated complete patency of the S-TFN covered stent at 2 wk. Post mortem histopathology showed rapid endothelialization of the S-TFN without excessive neointimal hyperplasia.
  
  
  CONCLUSIONS
  These results demonstrate that S-TFN significantly reduces platelet adhesion and aggregation compared with commercially available endograft materials. Furthermore, the hydrophilic surface may confer thromboresistance in vivo, suggesting that S-TFN is a possible superior material for covering stents.
authors.affiliation: Department of Surgery, Division of Vascular Surgery, David Geffen School of Medicine at the University of California-Los Angeles, Los Angeles, California 90025, USA. atulloch@mednet.ucla.edu
authors.forename: Allan W
authors.initials: AW
authors.lastname: Tulloch
authors.forename: Youngjae
authors.initials: Y
authors.lastname: Chun
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Levi
authors.forename: Kotekar P
authors.initials: KP
authors.lastname: Mohanchandra
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Carman
authors.forename: Peter F
authors.initials: PF
authors.lastname: Lawrence
authors.forename: David A
authors.initials: DA
authors.lastname: Rigberg
mesh_terms: D000497:Alloys / Q000737:chemistry*; D000792:Angiography; D000818:Animals; D020099:Coated Materials, Biocompatible; D057927:Hydrophobic and Hydrophilic Interactions; D007083:Iliac Artery / Q000000981:diagnostic imaging; D008422:Materials Testing; D023421:Models, Animal; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D011093:Polyethylene Terephthalates; D011138:Polytetrafluoroethylene / Q000737:chemistry; D015607:Stents; D034421:Sus scrofa; D013927:Thrombosis / Q000517:prevention & control*
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; D011093:Polyethylene Terephthalates; C013616:nitinol; D011138:Polytetrafluoroethylene