The regulation of liver regeneration by the plasmin/α2-antiplasmin system

Background/Aims: The regeneration after liver injury is regulated by the release and activation of several growth factors. The role of the plasmin/alpha(2)-antiplasmin (alpha(2)-AP) system in liver regeneration was investigated. Methods: CCl4 was injected intraperitoneally into the mice deficient (-/-) in fibrinolytic factors: alpha(2)-AP plasminogen (Plg) -/-, and Plg -/-.alpha(2)-AP -/-, and wild-type (WT) mice. The liver tissue was examined for its microscopic appearance, fibrinolytic activity, and fibronectin levels. Results: In the gene deficient and WT mice, the livers exhibited the same extent of necrosis 2 days after the CCl4 injection. The livers of the WT mice normalized after 7 days, and the alpha(2)-AP -/- mice normalized after 5 days. In contrast, the livers of the Plg -/- and Plg -/-.alpha(2)-AP -/- mice remained in the damaged state until 14 days after the liver injury. The injection of anti-alpha(2)-AP antibody in the WT mice improved the regeneration after the liver injury, and the injection of tranexamic acid in the alpha(2)-AP -/- mice reduced. Conclusions: These results suggest that the plasmin/alpha(2)-AP system played an important role in hepatic repair via clearance from the injury area. (C) 2003 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.