Background: University of Wisconsin solution (UW) may freeze at temperatures below -0.7 °C, damaging the graft. The present study assessed the effectiveness of the liver graft package protocol, which recommends filling a package with sufficient liquid to prevent grafts from sustaining freezing injury.
Methods: We filled ice cubes at two temperatures (-80 and -20 °C) around packages and performed a comparative study with four groups based on the temperature and filling of the second layer with lactated Ringer's solution (LR) (A: -80 °C, LR-; B: -80 °C, LR+; C: -20 °C, LR-; D: -20 °C, LR+). The bovine liver was used as a graft and preserved for 6 h in the first isolation bag filled with UW.
Results: While temperatures dropped below -0.7 °C at some points for 6 h in groups A, B, C, they never dropped to -0.7 °C in group D. The macroscopic findings in groups A, B, C showed freezing of the UW and grafts, but no such results in group D. A pathological study including electron microscopy showed freezing injury in groups A, B, and C but no significant changes in group D.
Conclusions: The graft package protocol prevents freezing of the UW and liver grafts.
Keywords: University of Wisconsin solution; freezing injury; graft package; organ preservation.