Improvement of the survival rate after rat massive hepatectomy due to the reduction of apoptosis by caspase inhibitor

BACKGROUND AND AIM: Acute liver failure after massive hepatectomy is caused by both necrosis and apoptosis in the remnant liver. We investigate the protective effect of the caspase inhibitor on apoptosis after massive hepatectomy in rats. METHODS: Benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (ZVAD-fmk) is a general inhibitor of the caspase. Male Wister rats weighing 200-300 g were divided into three groups: 90Hx group undergoing 90% hepatectomy, 95Hx group undergoing 95% hepatectomy, 95Hx + ZVAD group undergoing 95% hepatectomy and administration of ZVAD-fmk. The 7-day survival rate was studied, and the rats were sacrificed at the 1, 2, 3, 5, and 7th day after hepatectomy. The remnant liver tissues were stained with hematoxylin-eosin, and with proliferating cell nuclear antigen (PCNA) for evaluation of liver regeneration, and with TdT-mediated dUTP-biotin nick end labeling (TUNEL) and in situ oligo ligation method (ISOL) for evaluation of apoptosis. RESULTS: The 7-day survival rates were 100%, 0%, and 30%, in the 90Hx, 95Hx, and 95Hx + ZVAD groups, respectively. There was no significant difference in PCNA labeling index (LI) between the 95Hx and 95Hx + ZVAD groups. TUNEL and ISOL LI of 95Hx + ZVAD group were significantly lower than those of 95Hx group. Fatal liver failure after massive hepatectomy was characterized by more apoptosis and less mitosis of hepatocytes. ZVAD-fmk could significantly attenuate apoptosis of hepatocytes in the remnant liver and improve the survival rate after 95% hepatectomy in rats. CONCLUSION: Caspase inhibitors such as ZVAD-fmk may provide a new adjuvant therapy to treat liver failure after massive hepatectomy.