The Establishment And Regeneration Characteristics Of Small-for-size Liver Syndrome Model In Nude Mice

Objective: To establish the model of small for size liver syndrome throughmost of liver resection of nude mice. The survival curve, liver function, liverbiopsy and pathological examination are tested to confirm that theestablishment of the model. At the same time, the feasibility and condition ofsmall liver syndrome model and its regeneration characteristics are discussed.Methods: First,10cases of nude mice were taken with liver anatomy, toobserve the in vivo and in vitro liver anatomy. The liver weight percentage andthe proportion of each lobe of the liver were understood by the liver anatomy.Liver lobe resection skill was practiced.40cases of nude mice (5weeks, weight22.3±1.8g) were randomly divided into four groups, each group of10, only ondifferent proportions of hepatectomy respectively. Group1: remove25%ofliver tissue; Group2: remove50%of liver tissue; Group3: remove75%ofliver tissue; Group4: remove80%of liver tissue. The survival condition andsurvival time of postoperative nude mice were observed. The survival curveswere statistics drawn.0.1ml blood was drawn through cardiac puncture1hbefore surgery and,1,4,7,14,21,28d after surgery respectively for serumalanine aminotransferase (ALT), aspertate aminotransferase (AST), totalbilirubin (TBIL) and albumin (propagated) value test. The liver biopsy of nudemice were done in operation and2d,7d,28d and60d after theoperation(autopsy was done in time). HE staining for liver tissue sample wasdone for the pathological histological test and immunohistochemical test. Atthe same time, hepatocyte growth factor (HGF) and interleukin6(IL-6)immunohistochemical detection in the specimen were tested. The data were analyzed using one-way ANOVE analysis. Statistical significance was set atP<0.05.Results:1. Nude mice liver included six lobes. The weight of liver was about (3.63±0.05)%of body weight. Left lobe accounting for (38.44±0.41)%proportion ofliver, middle lobe accounting for (26.44±0.59)%, Triangle lobe accounting for(14.08±0.33)%, caudate lobe accounting for (11.84±0.53)%, right upper lobeaccounting for (3.49±0.28)%, right lower lobe accounting for (5.71±0.22)%.2. The survival rate at60d postoperative in group1,2,3,4was respectively100%,100%,70%and20%.3. Liver tissue in general observation: Preoperative, the liver of nude mice wasruddy color, texture was soft. The remained liver tissue of dead mice afterhepatectomy appeared yellow color, cholestatic state, varying degrees ofsteatosis, congestion swelling, volume increased. The texture was slightlyharder than the normal liver tissue. There were a small amount of ascites inabdominal cavity. On day2after hepatectomy, the liver tissues of group1and2appeared ruddy color and soft texture; while the liver tissues of nudemice in group3and group4were darker in color, the texture were slightlyharder and partly steatosis. There were a small amount of ascites in abdominalcavity in group4mice. On day7after hepatectomy, the liver tissues of mice ineach group regenerated and appeared ruddy color and soft texture,but ingroup3and group4varying degrees of steatosis. On day28after hepatectomy,the sizes of liver tissues of mice in all groups were almost the same aspreoperative. The regenerated liver tissues appeared ruddy color. On day60after hepatectomy, the volume of liver tissues of mice and the proportion ofliver weight in each group was significantly increased.4. There were no significant differences between before and after hepatectomyin group1for the values of ALT、AST、IBIL. The values of ALT、AST、IBILin group2were mildly increased on day1after hepatectomy and decreased on day7. The values of ALT、AST、IBIL in group3,4were significantlyincreased on day1after hepatectomy. In group4, the value of ALT was520.42±28.35U/L, AST was447.10±56.45U/L、IBIL was9.10±0.35umol/L.The values of ALB in group3,4were significantly decreased on day1afterhepatectomy. The value of ALB in group4was32.42±1.83U/L.5. The HE staining of normal liver tissue row by preoperative biopsyappeared: the central vein was clear, liver cell cytoplasm and nuclei were clear,no inflammatory cells infiltration. The liver tissue samples for HE staining ingroup1,2on2d postoperative showed: central venous mild bleeding,interstitial slightly edema, liver cell plasma loose, central vein and hepatic sinusmild expansion, portal area had a small amount of inflammatory cell infiltration.The normal liver tissue structure returned on60d postoperative. The liverbiopsy in group3on2d postoperative indicated: central vein moderatecongested, interstitial edema, sinus had obvious thrombosis, scattered liver cellnecrosis, the small cell vacuoles, and portal area showed inflammatory cellinfiltration. On60d postoperative, hepatic sinus expansion, cytoplasm andnucleus were clear. The liver biopsy in group4on2d postoperative showed:the central venous congestion, large areas of liver cell necrosis severely. Theliver biopsy in group4on60d after hepatectomy revealed: a small amount ofliver cell vacuolization, steatosis but significantly regeneration.6. The Immunohistochemistry staining for IL-6showed: IL-6was not expressedin the normal liver, while low level in group1after hepatectomy. Theexpression of IL-6was significantly increased in the liver of nude mice ingroup2,3on7d after hepatectomy, and decreased on day28,60after operation.IL-6was also expressed in the liver of nude mice in group4on day2,7afterhepatectomy. And, the expression of IL-6decreased after day28. In the deadnude mice, the level of expression of IL-6was low.7. The expression of HGF was very low in the normal liver. Low level of HGFwas tested in group1after hepatectomy. Group22and7d after nude mice liver tissue in HGF expression in great quantities, postoperative28and60dexpression gradually reduced. The level of HGF in group3,4after operationincreased. The level of HGF decreased after day28.Conclusion:1. The nude mice model for Small-for-size liver syndrome (SFSS) can beestablished successfully by80%liver hepatectomy.2. The expression of IL-6and HGF increased after hepatectomy which isinvolved in hepatocyte-regeneration.