Liver regeneration: Literature review

Liver regeneration is a highly organized tissue growth process and is the livers most important reaction to aggression. The complex mechanisms involved in this process encompass a variety of regenerative pathways that are specific to the different types of aggression. The most studied form of liver regeneration is that which occurs after the loss of hepatocytes in an acute injury, such as in the regenerative process of rodents after partial hepatectomy or administration of harmful chemicals (CCl4, paracetamol, allyl alcohol). These experimental models revealed extracellular and intracellular signaling pathways that are used to return the liver to the size and weight equivalent to those prior to the injury. Understanding the liver regeneration process is a challenge that is justified by the numerous interactions of different cellular components, various mitogenic factors (complete and incomplete), complex mitogenic pathways, and acute phase inflammatory proteins. Hepatocytes, cholangiocytes, and liver progenitor cells have been shown to have regenerative behavior. The regenerative activities of hepatocytes and cholangiocytes are typically characterized by phenotypic fidelity (multiplication), however, when normal regeneration is thwarted, hepatocytes and cholangiocytes function as facultative stem cells (dedifferentiate) or transdifferentiate to restore normal liver structure. This review traces the path taken in recent decades in the study of liver regeneration and highlights new concepts in the area.