title: The ex-vivo-shunt-model: novel approach for assessing the thrombogenicity of vascular implants.
abstract: OBJECTIVE
  Disadvantages associated with commercially available vascular implants necessitate alternative strategies to develop new vascular prostheses. Although many tissue characterizing strategies have been defined, no valid test for thrombogenicity exists. Here we introduce a novel concept for thrombogenicity testing of vascular implants
  
  
  METHODS
  Silastic tubes were implanted into the carotid arteries of 12 sheep. After placing these shunts, tc99m-labeled platelets were administered and test-vessels were put in between the shunts. Native autologous (n=6), as well as native/acellularized allogeneic (n=6/n=6), and xenogeneic (n=6/n=6) carotid arteries and allogeneic (n=6/n=6) and xenogeneic (n=6/n=6) carotid arteries reseeded with allogeneic endothelial-cells, fibroblasts and myocytes were evaluated. Number and time course of intra-operatively deposited platelets were evaluated with a Geiger-counter; certain areas of platelet deposition located, envisioned and characterized by a gamma-camera and scanning electron-microscopy afterwards.
  
  
  RESULTS
  Counter results revealed no significant different platelet depositions when comparing silastic tubes with either autologous or allogeneic native carotid arteries. However, starting 5 minutes after placement, acellularized/reseeded allogeneic (p=0.001/p=0.00004), and xenogeneic (p=0.0001/p=0.01) carotid arteries showed significantly more platelet depositions than native autologous carotides. Moreover, it was possible to show that almost no platelets adhere to native vessels or silastic tubes, thus proving the test method itself.
  
  
  CONCLUSIONS
  The Ex-Vivo-Shunt-Model is a valid method to measure and envision the intrinsic thrombogenicity of vascular implants.
authors.affiliation: Division for Thoracic-, and Cardiovascular Surgery, Hannover Medical School, Germany. Wilhelmi@thg.mh-hannover.de
authors.forename: M H
authors.initials: MH
authors.lastname: Wilhelmi
authors.forename: K F
authors.initials: KF
authors.lastname: Gratz
authors.forename: R
authors.initials: R
authors.lastname: Mischke
authors.forename: M
authors.initials: M
authors.lastname: von Depka
authors.forename: D
authors.initials: D
authors.lastname: Noske
authors.forename: T
authors.initials: T
authors.lastname: Francis
authors.forename: A
authors.initials: A
authors.lastname: Haverich
authors.forename: H
authors.initials: H
authors.lastname: Mertsching
mesh_terms: D000714:Anastomosis, Surgical / Q000379:methods*; D000818:Animals; D001807:Blood Vessel Prosthesis / Q000009:adverse effects*; D019917:Blood Vessel Prosthesis Implantation; D002339:Carotid Arteries / Q000503:physiopathology / Q000637:transplantation* / Q000648:ultrastructure; D023421:Models, Animal; D008955:Models, Cardiovascular; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D012756:Sheep; D013552:Swine; D013927:Thrombosis / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology