MBSJ MCC Young Scientist Award 2012 Liver regeneration: a unique and flexible reaction depending on the type of injury.

The liver can be thought of as a mysterious organ, because it has an elegant regenerative capability. This phenomenon has been well known since ancient times and is already applied to medical treatments for severe hepatic disorders by transplanting portions of liver received from living donors. However, it was not until quite recently that the mechanism underlying the principle of liver regeneration was investigated more deeply. Recent advances in the technologies for characterizing cell properties and examining the molecular nature of cells are enabling us to understand what occurs in the regenerating liver. After acute liver damage, hepatocytes actively proliferate in response to external stimulation by humoral factors. However, in the chronically injured liver, hepatocytes cannot proliferate well, but biliary cells appearing after chronic liver damage form primitive ductules around portal veins of the liver. These biliary cells may have a multiple origin, including hepatocytes, and contain progenitor cells giving rise to both hepatocytes and biliary cells, or represent cells that can be directly converted into hepatocytes. Although liver regeneration is more complicated than we had thought, unremitting efforts by researchers will certainly connect the numerous findings obtained in basic research with the development of new therapeutic strategies for liver diseases.