Alteration of MRP2 expression and the graft outcome after liver transplantation.

Purpose: Multidrug resistance-associated protein (MRP) 2 is a glutathione conjugate in the canalicular membrane of hepatocytes. Early graft damage after liver transplantation (LT) can result in alteration of MRP2 expression. The purpose of this study was to evaluate the relationship between the pattern of MRP2 alteration and graft outcome. Methods: Forty-one paraffin-embedded liver graft tissues obtained by protocol biopsy within 2 months after LT; these were stained using monoclonal antibodies of MRP2. We selected 15 live donor biopsy samples as a control, that showed homogenous canalicular staining for MRP2. The pattern of canalicular MRP2 staining of graft was classified into 3 types: homogenous (type CO), focal (type C1), and no (type C2,) staining of the canaliculi. Results: In total, 17.1% graft tissues were type CO, 36.6% were type C1, and 46.3% were type C2. The median operation time was longer in patients with type C2 (562.6 minutes) than in patients with type CO (393.8 minutes) (P = 0.038). The rates of posttransplant complications were higher in patients with type C2 (100%) than in patients with type CO (42.9%) and C1 (73.3%) (P < 0.001). Conclusion: MRP2 expression pattern was altered in 82.9% after LT. The pattern of MRP2 alteration was associated with longer operation time and higher rates of post-LT complications.