Effects of duration of ischemia and donor pretreatment with methylprednisolone or its macromolecular prodrug on the disposition of indocyanine green in cold-preserved rat livers

Abstract

Purpose: Cold preservation of the liver before transplantation may change uptake and excretory functions of hepatocytes. We hypothesized that an increase in the duration of preservation would result in a progressive decrease in the hepatic uptake and/or biliary excretion of indocyanine green (ICG), which would be attenuated by pharmacologic interventions.

Methods: Donor rats (n = 40) were administered saline (control) or single 5 mg/kg doses of methylprednisolone (MP) or its liver-targeted prodrug (DMP) 2 h prior to liver harvest. Following preservation in cold University of Wisconsin solution for 0, 24, 48, or 72 h, livers were reperfused in a single-pass manner for 30 min in the presence of ICG (approximately 4 microg/ml), followed by 60 min of ICG-free perfusion. The inlet, outlet, and bile concentrations of ICG were measured periodically by high performance liquid chromatography (HPLC), and kinetic parameters were estimated.

Results: Effects of duration of preservation: In unpreserved livers, a significant portion of ICG dose (16%) was effluxed from the liver during the washout period. Cold preservation for 24-72 h progressively increased (p < 0.05) the efflux of ICG (>2-fold at 72 h). Similarly, average extraction ratio showed a modest (30-40%) decrease with increasing preservation time (p < 0.05). However, biliary excretion of ICG showed the most sensitivity to the preservation time (14 to >800-fold decline). Effects of pretreatment: DMP caused significant (p < 0.05) increases in biliary ICG levels (>12-fold) and bile flow rates (6-15-fold) of preserved livers. Although MP pretreatment significantly (p < 0.05) increased (6-fold) bile flow rates in 48-h preserved livers, its effects on biliary ICG levels were not significant (p > 0.05).

Conclusions: Biliary excretion of ICG is the most sensitive kinetic parameter to prolonged cold ischemia-reperfusion injury in a rat liver perfusion model. The injury may be significantly attenuated by pharmacologic pretreatment of the liver donors.