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

Early graft dysfunction develops in up to 10-50% of liver transplanted patients and is related to the number of risk factors which identify marginal livers. Marginal livers are defined by the presence of af least one of the following risk factors: (1) donor aged > 50 years; (2) donor with hemodynamic instability 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 involving less than 25% of hepatocytes is not considered sufficient to identify a marginal donor, although 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 hepatocytes and the increased cell volume cause an impairment of liver microcirculation. Steatosis is associated with decreased capability of ATP production and storage, with increased lipid peroxidation, and with increased release of tumor necrosis factor-a which is believed to be responsible of the lung damage possibly occurring after transplant. The assessment of the type and extent of steatosis requires liver biopsy, not usually indicated in healthy individual. In the transplant setting a precise assessment of steatosis is the prominent reason for performing a liver biopsy of the donor liver.