A novel function of thrombin-activatable fibrinolysis inhibitor during rat liver regeneration and in growth-promoted hepatocytes in primary culture.

Thrombin-activatable fibrinolysis inhibitor (TAFI) exhibits anti-fibrinolytic activity by removing C-terminal lysine residues from fibrin or plasminogen receptor proteins on the cellular surface, and plays an important role in the regulation of fibrinolysis. In this study, we examined the regulation of TAFI in hepatocytes during liver regeneration, and revealed its pivotal role in hepatocyte proliferation. In rat models, partial hepatectomy or carbon tetrachloride (CCl4)-induced acute liver injury suppressed the levels of plasma TAFI activity and hepatic TAFI mRNA, whereas this operation markedly increased both the hepatic plasmin activity and the level of proliferating cell nuclear antigen.

Formation of rat hepatocyte spheroids on agarose.

The hepatocyte spheroid formation on the Primariatrade mark dish (PM) occurred as a result of cell migration, adhesion, and shape changes. On the other hand, hepatocytes plated on 1.5% agarose-coated dishes did not attach to the dishes.

Plasminogen activator/plasmin system regulates formation of the hepatocyte spheroids.

The isolated rat hepatocytes inoculated onto the surface of positively charged culture dishes are anchored initially and then begin to migrate and aggregate gradually to form multicellular spheroids detached from the dish. We studied the roles of fibrinolytic factors in the spheroid formation. The fibrinolytic factors, tissue-type plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA), were increased in the course of spheroid formation.