title: Storage of porcine articular cartilage at high subzero temperatures.
abstract: OBJECTIVE
  Transplantation of osteochondral allograft tissue can treat large joint defects but is limited by tissue availability, surgical timing, and infectious disease transmission. Fresh allografts perform the best but requirements for infectious disease testing delay the procedure with subsequent decrease in cell viability and function. Hypothermic storage at lower temperatures can extend tissue banking time without loss of cell viability and, therefore, increase the supply of allograft tissue. This study investigated the effects of different cryoprotectant solutions on intact AC at various subzero temperatures.
  
  
  METHODS
  10 mm porcine osteochondral dowels were immersed for 30 minutes in various combinations of solutions [(XVIVO, propylene glycol (51% w/w), sucrose (46% w/w)] cooled to various subzero temperatures (-10, -15, and -20 degrees C), and held for 30 min. After warming, 70 mum slices were stained with membrane integrity dyes, viewed under fluorescence microscopy and cell recovery calculated relative to fresh controls.
  
  
  RESULTS
  Results demonstrated excellent cell recovery (>75%) at -10 degrees C provided ice did not form. Excellent cell recovery (>70%) occurred at -15 degrees C in solutions containing 51% propylene glycol but formation of extra-matrix ice in other solutions resulted in significant cell loss. All groups had <6% cell recovery at -20 degrees C and propylene glycol did not provide a protective effect even though extra-matrix ice did not form
  
  
  CONCLUSIONS
  These results suggest that extra-matrix ice plays an important role in cell damage during cryopreservation. Excellent cell recovery can be obtained after storage at subzero temperatures if ice does not form. Hypothermic preservation at high subzero temperatures may extend AC storage time in tissue banks compared to current techniques.
authors.affiliation: Department of Surgery, University of Alberta, #1002, 8215-112St, College Plaza, Edmonton, AB Canada T6G 2C8. nadr@interbaun.com
authors.forename: N M
authors.initials: NM
authors.lastname: Jomha
authors.forename: G K
authors.initials: GK
authors.lastname: Law
authors.forename: L E
authors.initials: LE
authors.lastname: McGann
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism*; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents; D005615:Freezing; D013552:Swine
chemical_list: D003451:Cryoprotective Agents