Viability of hypothermic preserved muscle determined by gene expression levels

We report a muscle viability index (MVI) that reflects mRNA degradation. The viability of hypothermically preserved (4°C) rat skeletal muscle was evaluated using this MVI. To evaluate the hypothermic ischaemic insult of the muscle, 21 hind limbs of Fischer rats (three subgroups of seven limbs each) were hypothermically preserved for 1 h, 3 h and 6 h, before harvesting the tibialis anterior muscle. To investigate reperfusion injury after hypothermic preservation, an additional 28 limbs were transplanted to recipient Fischer rats after hypothermic ischaemia for either 3 h or 6 h. The transplanted muscles were harvested on either day 3 or day 7 after transplantation. Seven fresh muscles were also harvested, and used as controls. In the 3 h ischaemia group, the MVIs of both the hypothermic-ischaemia and the ischaemia-reperfusion subgroups were comparable to the controls. Likewise, there were no significant differences between the controls and the 6 h hypothermic ischaemia and ischaemia-reperfusion subgroups. These results show that muscle viability is maintained with hypothermic preservation of up to 6 h, and after reperfusion. Therefore, in clinical replantations the amputated extremity should be preserved under hypothermic conditions from the time of injury to the time of surgery.