title: Preclinical evaluation of ice-free cryopreserved arteries: structural integrity and hemocompatibility.
abstract: OBJECTIVE
  Arterial allografts are routinely employed for reconstruction of infected prosthetic grafts. Usually, banked cryopreserved arteries are used; however, existing conventional freezing cryopreservation techniques applied to arteries are expensive. In contrast, a new ice-free cryopreservation technique results in processing, storage and shipping methods that are technically simpler and potentially less costly. The objective of this study was to determine whether or not ice-free cryopreservation causes tissue changes that might preclude clinical use.
  
  
  METHODS
  Conventionally frozen cryopreserved porcine arteries were compared with ice-free cryopreserved arteries and untreated fresh controls using morphological (light, scanning electron and laser scanning microscopy), viability (alamarBlue assay) and hemocompatibility methods (blood cell adhesion, thrombin/antithrombin-III-complex, polymorphonuclear neutrophil-elastase, β-thromboglobulin and terminal complement complex SC5b-9).
  
  
  RESULTS
  No statistically significant structural or hemocompatibility differences between ice-free cryopreserved and frozen tissues were detectable. There were no quantitative differences observed for either autofluorescence (elastin) or second harmonic generation (collagen) measured by laser scanning microscopy. Cell viability in ice-free cryopreserved arteries was significantly reduced compared to fresh and frozen tissues (p < 0.05).
  
  
  CONCLUSIONS
  The formation of ice in aortic artery preservation did not make a difference in histology, structure or thrombogenicity, but significantly increased viability compared with a preservation method that precludes ice formation. Reduced cell viability should not reduce in vivo performance. Therefore, ice-free cryopreservation is a potentially safe and cost-effective technique for the cryopreservation of blood vessel allografts.
authors.affiliation: Thoracic, Cardiac and Vascular Surgery, University Hospital, Tübingen, Germany.
authors.forename: Agnes J T
authors.initials: AJ
authors.lastname: Huber
authors.forename: Kelvin G M
authors.initials: KG
authors.lastname: Brockbank
authors.forename: Iris
authors.initials: I
authors.lastname: Riemann
authors.forename: Martina
authors.initials: M
authors.lastname: Schleicher
authors.forename: Katja
authors.initials: K
authors.lastname: Schenke-Layland
authors.forename: Olaf
authors.initials: O
authors.lastname: Fritze
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Wendel
authors.forename: Ulrich A
authors.initials: UA
authors.lastname: Stock
mesh_terms: D000826:Animal Testing Alternatives; D000818:Animals; D001013:Aorta, Thoracic / Q000473:pathology* / Q000637:transplantation; D001672:Biocompatible Materials; D001777:Blood Coagulation / Q000502:physiology; D002470:Cell Survival; D003362:Cost-Benefit Analysis; D015925:Cryopreservation / Q000191:economics / Q000379:methods*; D005260:Female; D006461:Hemolysis / Q000502:physiology; D007053:Ice / Q000009:adverse effects*; D008297:Male; D008422:Materials Testing / Q000379:methods*; D023421:Models, Animal; D012449:Safety; D013552:Swine; D014184:Transplantation, Homologous
chemical_list: D001672:Biocompatible Materials; D007053:Ice