Capacity of hepatic regeneration following a second partial hepatectomy in rats

In hepatic surgery, the number of repeated hepatectomy has increased for recurrent tumors after the first hepatectomy. We examined here, whether or not hepatic regeneration after the second partial hepatectomy was similar to that of the remnant liver after the primary partial hepatectomy. Using a new model of a second partial hepatectomy in rats, three groups of rats were studied. Group I rats underwent a standard one-third partial hepatectomy (P-PHx group, n=30). Group II rats underwent a one-third hepatectomy 2 weeks after a two-thirds hepatectomy was performed (S-PHx group, n=30). As a control, Group III rats underwent sham surgery. In each group, the rats were sacrificed at different time points postoperatively to evaluate changes in blood chemistry and to estimate the liver regenerative response in the remnant liver (weight, immunohistochemistry; BrdU, MIB-5) as well as expression of the hepatocyte growth factor. In the S-PHx group, a significant decrease was detected in the restitution of the liver mass until 24 h postoperatively which was closely associated with the number of mitotic hepatocytes. The S-PHx group showed significant signs of liver dysfunction until 48 h and significantly increased serum hyaluronic acid levels until 72 h in comparison to the P-PHx group. In situ RT-PCR analysis indicated that in the P-PHx group HGF transcripts were expressed between 24 and 48 h in the remnant liver, while in the S-PHx group HGF transcripts were expressed only at 24 h postoperatively. Our findings suggested that second partial hepatectomized rats exhibit a retarded hepatic regeneration during the early postoperative phase due to a depressed HGFmRNA expression.