Expression of BCL-2 in liver grafts after adenoviral transfer improves survival following prolonged ischemia and reperfusion in rat liver transplantation

Apoptosis represents a crucial mechanism of ischemia-reperfusion injury after liver transplantation. Bcl-2 may inhibit apoptosis. This study investigates the effect on ischemia/ reperfusion injury and survival after rat liver transplantation of adenoviral bcl-2 transfer into donor livers. Methods. A nonreplicative adenovirus, expressing bcl-2 under control of a tetracyclin-inducible promoter (adv TetOn bcl-2) was used to treat male Lewis rats in combination with a second adenovirus transferring the TetOn repressor protein under control of a cytomegalovirus promoter (advCMVRep). Virus induction was achieved by addition of doxycyclin to the drinking water. Controls were pretreated with a control adenovirus (advCMV GFP) or with doxycycline. Liver transplantations were performed after 16-hour graft storage. Bcl-2 expression was evaluated by Western blot and immunohistology. Survival was monitored for 7 days, and tissue specimens were collected at 24 hours and 7 days post reperfusion. Results. After pretreatment with advTetOn bcl-2/adv CMVRep, intrahepatic bcl-2 expression was evident at 24 hours and 7 days but was absent among controls. Bcl-2 expression was detected in hepatocytes and, to a high degree, in sinusoidal lining cells. TUNEL-positive sinusoidal lining cells were strikingly reduced after bcl-2 transfer (0.1 +/- 0.3 cells/hpf, mean +/- SD) compared to control virus (4.8 +/- 2.3) or doxycyclin-treated grafts (1.3 +/- 0.2); P < .05. After bcl-2 treatment, survival after transplantation was 100%, whereas it was 50% in both control groups (P = .035). Conclusion. The study shows the feasibility of transient, doxycyclin-cont rolled adenoviral gene transfer in a transplantation model. Bcl-2 expression increased survival after ischemia/reperfusion in rat liver transplantation, potentially through protection of sinusoidal lining cells.