The mechanism of injury in a steatotic liver graft during cold preservation.

BACKGROUND: Fatty livers are more prone to primary nonfunction after transplantation. It is known that cell injury is strongly associated with alterations in the content and composition of membrane lipids. We assumed that plasma membrane (PM) fluidity, which is the most important property of the membrane, differed between fatty and normal livers.
METHODS: The livers from obese and lean Zucker rats were flushed with cold Ringer's lactate and University of Wisconsin (UW) solution via the portal vein and preserved in cold UW solution for 24 hr. Histological examinations of electron microscopy were performed to investigate of sinusoidal lining cells (SLCs). PMs were isolated using a discontinuous density gradient of Percoll, and the lipid compositions were determined by chromatography.
RESULTS: SLCs of fatty livers were markedly injured compared with control livers even after short preservation time. Moreover, many blebs were observed in the obese rats even after short preservation time. As for PM lipid composition, the cholesterol/phospholipid (PL) ratio of total PM was 0.14+/-0.03 in the obese rats and 0.21+/-0.03 in the lean rats (P<0.05). The relative proportions of polyunsaturated fatty acids among PLs in PM were 35.7+/-1.2% vs. 45.9+/-1.5% (P<0.0001). These results indicated that the fluidity of the PM in the obese rats is decreased after exposure to low temperatures.
CONCLUSIONS: Our results suggest that steatotic livers from obese donors are more susceptible to cold preservation injury than livers without steatosis because of the severe deterioration of SLCs, and it is associated with PM fluidity even after short-term cold preservation.