What is the real contribution of extrahepatic cells to liver regeneration?

Extrahepatic cells, especially bone marrow (BM) cells, might contribute to liver repair, but recent published evidence suggests that they do not play a role in the normally regenerating liver. The mechanism by which extrahepatic cells express a liver-specific function in the liver, whether by transdifferentiation or by cell fusion, remains unclear. In this review, we investigate the status of findings on this controversial subject and summarize the recent research.