title: Biomechanical changes from long-term freezer storage and cellular reduction of tracheal scaffoldings.
abstract: OBJECTIVE
  To determine structural biomechanical changes in tracheal scaffolds resulting from cellular reduction and storage at -80(o) C.
  
  
  METHODS
  Laboratory-based study.
  
  
  METHODS
  Forty-four rabbit tracheal segments were separated into four treatment groups: untreated (group A, control), cellular-reduced (group B), storage at -80(o) C followed by cellular reduction (group C), and cellular-reduced followed by storage at -80(o) C (group D). Tracheal segments were subjected to uniaxial tension (n = 21) or compression (n = 23) using a universal testing machine to determine sutured tensile yield load and radial compressive strengths at 50% lumen occlusion. Mean differences among groups for tension and compression were compared by analysis of variance with post-hoc Tukey-Kramer test.
  
  
  RESULTS
  The untreated trachea (group A) demonstrated mean yield strength of 5.93 (± 1.65) N and compressive strength of 2.10 (± 0.51) N. Following treatment/storage, the tensile yield strength was not impaired (group B = 6.79 [± 1.58] N, C = 6.21 [± 1.40] N, D = 6.26 [± 1.18]; P > 0.10 each). Following cellular reduction, there was a significant reduction in compressive strength (group B = 0.44 N [± 0.13], P < 0.0001), but no further reduction due to storage (group C = 0.39 N [± 0.10]; P = 0.97 compared to group B).
  
  
  CONCLUSIONS
  The data suggest cellular reduction leads to loss of compressive strength. Freezing at -80°C (either before, or subsequent to cellular reduction) may be a viable storage method for tracheal grafts.
authors.affiliation: Center for Voice, Airway and Swallowing, Department of Otolaryngology, Augusta, Georgia, U.S.A.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Jones
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Rueggeberg
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Cunningham
authors.forename: Hunter A
authors.initials: HA
authors.lastname: Faircloth
authors.forename: Tanima
authors.initials: T
authors.lastname: Jana
authors.forename: Donald
authors.initials: D
authors.lastname: Mettenburg
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Waller
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Postma
authors.forename: Paul M
authors.initials: PM
authors.lastname: Weinberger
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology*; D002452:Cell Count; D019245:Compressive Strength / Q000502:physiology; D015925:Cryopreservation; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D011817:Rabbits; D013718:Tensile Strength / Q000502:physiology; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds; D014132:Trachea / Q000166:cytology*
keywords: Allograft; mechanical phenomena; tensile strength; tissue engineering; tissue transplantation