**1. Introduction**

Orthotropic whole and split liver transplantation are successful and well-established treatments for liver disease. However, the short supply of donor organs is a major obstacle to the widespread use of this therapy (Merion, 2010). Recent research has focused on cell transplantation as a therapy for liver disease. Although only a small number of hepatocytes can be transplanted into the liver by transfusion into the portal circulation, the transplanted cells can regenerate the normal hepatic tissue when liver growth is impaired as a result of continuous hepatic damage (Roy-Chowdhury & Roy-Chowdhury, 2011; Gilgenkranz, 2010). A number of animal models have demonstrated that much of the liver can be replaced via repopulation by a small number of transplanted hepatocytes, which restore normal liver functions and improve recipient survival. Hepatocyte transplantation is therefore expected to be used as a therapy for human liver disease. To optimize the therapeutic application of hepatocyte transplantation, however, number of problems such as the methods to monitor and evaluate the functionality of the transplanted cells and the suppression of host immunological responses against the transplanted cells require mitigation.

The cell transplantation model, which uses Fischer344 (F344) rats as donors and F344 congenic analbuminemic (F344-alb) rats as recipients, provides an excellent system for the investigation of cell transplantation, because no immunosuppressants are required for cell transplantation. In addition, the transplantability can be accurately evaluated with immunohistochemistry to stain for albumin, using PCR to detect albumin mRNA and genomic DNA, and by measuring serum albumin protein. In this review, we describe the hepatocyte transplantation system that uses F344 and F344-alb rats to study the intrahepatic hepatocyte transplantation.
