Effect of naked eukaryotic expression plasmid encoding rat augmenter of liver regeneration on acute hepatic injury and hepatic failure in rats

AIM: To study the protective effect of eukaryotic expression plasmid encoding augmenter of liver regeneration (ALR) on acute hepatic injury and hepatic failure in rats. METHODS: The PCR-amplified ALR gene was recombined with pcDNA3 plasmid, and used to treat rats with acute hepatic injury. The rats with acute hepatic injury induced by intraperitoneal injection of 2 mL/kg 50% carbon tetrachloride (CCl(4)) were randomly divided into saline control group and recombinant pcDNA3-ALR plasmid treatment groups. Recombinant pcDNA3-ALR plasmid DNA (50 or 200 microg/kg) was injected into the rats with acute hepatic injury intravenously, intraperitoneally, or intravenously and intraperitoneally in combination 4 h after CCl(4) administration, respectively. The recombinant plasmid was injected once per 12 h into all treatment groups four times, and the rats were decapitated 12 h after the last injection. Hepatic histopathological alterations were observed after HE staining, the expression of proliferating cell nuclear antigen (PCNA) in liver tissue was detected by immunohistochemical staining, and the level of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was determined by biochemical method. The recombinant plasmid DNA (200 microg/kg) and saline were intraperitoneally injected into the rats with acute hepatic failure induced by intraperitoneal injection of 4 mL/kg 50% CCl(4) after 4 h of CCl(4) administration, respectively. Rats living over 96 h were considered as survivals. RESULTS: The sequence of ALR cDNA of recombinant pcDNA3-ALR plasmid was accordant with the reported sequence of rat ALR cDNA. After the rats with acute hepatic injury were treated with recombinant pcDNA3-ALR plasmid, the degree of liver histopathological injury markedly decreased. The pathologic liver tissues, in which hepatic degeneration and necrosis of a small amount of hepatocytes and a large amount of infiltrating inflammatory cells were observed, and they became basically normal in the most effective group after four times of injection of recombinant pcDNA3-ALR plasmid. The indexes of PCNA significantly increased in the recombinant pcDNA3-ALR plasmid treatment groups compared to model group. The level of serum AST and ALT remarkably reduced in recombinant pcDNA3-ALR plasmid treatment groups compared to model group. The results showed that the effect of 200 microg/kg recombinant pcDNA3-ALR plasmid in the rats with acute liver injury was stronger than that of 50 microg/kg pcDNA3-ALR DNA. The effect of intravenous injection of recombinant pcDNA3-ALR plasmid was better. After the rats with acute hepatic failure were treated with recombinant pcDNA3-ALR plasmid, the survival rate (40%) significantly increased in treatment groups compared to control group (15%, P<0.01). CONCLUSION: The ALR gene may play an important role in relieving acute hepatic injury and hepatic failure by promoting hepatic cell proliferation and reducing level of AST and ALT in CCl(4)-intoxicated rats.