Liver - Regeneration

Regeneration

The liver is the only internal human organ capable of natural regeneration of lost tissue; as little as 25% of a liver can regenerate into a whole liver. This is, however, not true regeneration but rather compensatory growth. The lobes that are removed do not regrow and the growth of the liver is a restoration of function, not original form. This contrasts with true regeneration where both original function and form are restored.

This is predominantly due to the hepatocytes re-entering the cell cycle. That is, the hepatocytes go from the quiescent G0 phase to the G1 phase and undergo mitosis. This process is activated by the p75 receptors. There is also some evidence of bipotential stem cells, called hepatic oval cells or ovalocytes (not to be confused with oval red blood cells of ovalocytosis), which are thought to reside in the canals of Hering. These cells can differentiate into either hepatocytes or cholangiocytes, the latter being the cells that line the bile ducts.

Scientific and medical works about liver regeneration often refer to the Greek Titan Prometheus who was chained to a rock in the Caucasus where, each day, his liver was devoured by an eagle, only to grow back each night. Some think the myth indicates the ancient Greeks knew about the liver’s remarkable capacity for self-repair, though this claim has been challenged.