Introduction: Hepatocyte Growth Factor and Met Receptor, from Discovery to Therapeutic Implications

The mechanism for ingenious tissue regeneration in mammals is roughly divided into two distinct systems. One is a system in which undifferentiated, vigorously proliferative stem cells assume the principal role in tissue regeneration. It operates to regenerate and repair tissues comprising differentiated cells that are no longer capable of proliferation, such as the hemopoietic tissue of bone marrow, nerve tissues and muscles. The other, termed the simple duplication system, is the regeneration for tissues whose cellular components are mature and differentiated, yet vitally capable of proliferation as seen in the regeneration of parenchymal organs such as the liver, kidney, and lung. Therefore, for organs with complicated multi-cellular architecture such as the liver, kidney, and lung, treatment of an injury by activation of simple duplication system will be a means of therapy in accordance with nature.