Donor liver steatosis and graft selection for liver transplantation: a short review.

Early graft dysfunction devel- ops in up to 10-50% of liver transplanted pa- tients and is related to the number of risk fac- tors which identify marginal livers. Marginal liv- ers are defined by the presence of at least one of the following risk factors: (1) donor aged > 50 years; (2) donor with hemodynamic instabili- ty or with a residence time in ICU greater than 5 days; (3) donor with hypersodiemia; (4) donor with HCV or HBV infection; and (5) donor with macrovescicular steatosis present in > 25% of hepatocytes. The presence of steatosis involv- ing less than 25% of hepatocytes is not consid- ered sufficient to identify a marginal donor, al- though it may be associated with some risk of early or late graft failure. The reason is that the steatotic liver is characterized by a decreased tolerance to ischemia/reperfusion. It has been observed that the accumulation of fat in the he- patocytes and the increased cell volume cause an impairment of liver microcirculation. Steato- sis is associated with decreased capability of ATP production and storage, with increased lipid peroxidation, and with increased release of tumor necrosis factor-α which is believed to be responsible of the lung damage possibly oc- curring after transplant. The assessment of the type and extent of steatosis requires liver biop- sy, not usually indicated in healthy individual. In the transplant setting a precise assessment of steatosis is the prominent reason for per- forming a liver biopsy of the donor liver.