Liver gene expression and increase in albumin synthesis by fetal hepatocytes transplanted into analbuminemic rats.

This report describes the evolution of hepatocytes isolated from 21-day fetuses and transplanted into spleens of Nagase analbuminemic rats which have negligible serum albumin levels due to a mutation affecting albumin mRNA processing. Albumin and alpha-fetoprotein expression, in addition to other parameters related to cellular proliferation status (thymidine kinase and proliferating cell nuclear antigen expression) were studied as indicative of the behavior and evolution of the cells. In recipient rats, only a few clusters of hepatocytes could be observed in the red pulp of the spleen 24 h after transplantation. The fetal hepatocytes migrated to the liver and could be seen in portal branches immediately after transplantation. Fifteen days later, albumin mRNA was detected in recipient livers and was expressed throughout the entire 3-month study. Alpha-fetoprotein was not detected. Cell proliferation was not relevant, although 3 months after transplantation, the proliferation rates appeared to show a tendency to increase. These data demonstrate that fetal hepatocytes transplanted into spleen migrate to liver, settle there and acquire an adult phenotype free of malignant transformation. Our study is a first step towards the thorough understanding of fetal hepatocyte transplantation. The next steps will involve in-depth studies of the possibilities of genetic manipulation to achieve a high degree of repopulation/expression, employing the least possible number of donor cells, and of how the cells reach the liver parenchyma, overcoming the endothelial barrier.