|Budget Amount *help
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2000: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1999: ¥1,600,000 (Direct Cost: ¥1,600,000)
Massive hepatectomy often induced lethal hepatic failure. The mechanism has been described using two theories : indirect injury caused by microcircular disturbance induces necrosis to hepatocytes, and direct injury caused by cytotoxic disturbance induces apoptosis to hepatocyte.
We investigated the mechanism using our original experimental rat partial hepatectomy (PHx) models.
Method : We use male Wistar rats. Rats were anesthetized with diethylether, performed 90%PHx and 95%PHx. The rats were divided into the following two groups : group 1, 90%PHx, as a maximum procedure of hepatectomy model, group 2, 95%PHx, as a lethal hepatic failure model. We investigated serum concentration of interleukin (IL)-1b, IL-6, tumor necrosing factor (TNF)-a, as a index of hypercytokinemia. Histological findings of remnant liver were also examined by hematoxylyn and eosin (HE) staining. Apoptotic hepatocytes were determined by using DAPI and TUNEL assay. Bcl-x protein (anti-apoptotic member of the Bcl
-2 family) expression of remnant liver was studied by western blot analysis.
Result : Serum concentrations of IL-1b, IL-6, TNF-a, were higher in group 2 than in group 1. HE staining showed that more degeneration hepatocytes and little mitosis appeared in group 2. Apoptotic hepatocytes were more in group 2 than in group 1. Bcl-x protein was expressed more in group 1 than in group 2.
Conclusion : Apoptosis is one of the most important factors in the hepatic failure after excessive hepatectomy.
We applicated cDNA micoarray analysis in this models to clarify the mechanism of hepatic failure after excessive hepatectomy. The cell cycle of hepatocyte was stopped by overexpression of p21, ubiquitin and many cyclins. Apoptosis of hepatocyte was progressed by overexpression of Fas, many caspases and cytochrome C.Furthermore, genes of heat shock protein which protected from liver injury were rexpressed in 95%PHx group.
Results of Exp.1 demonstrate that expression of Bcl-xL protein as an anti-apoptotic factor or regeneration factor contributes to survival after 90%PHx. We therefore transfected human bcl-2 gene (hbcl-2) to DA rat livers by an adenovirus vector. The hbcl-2 was efficiently expressed. 95%PHx was then performed. Liver damage was improved and the apoptotic cell count decreased, but the rats died.
We concluded that transfection of hbc1-2 gene partly prevents cytotoxity (apoptosis), but cannot ensure survival. Thus, some other factor is required (e.g, a regeneration stimulator) to maintain life in these models. Less