In vitro evidences of epithelial to mesenchymal transition in low cell-density cultured human fetal hepatocytes.

Culturing fetal hepatocytes in high cell-density allowed stabilization of the hepatocyte phenotype up to 8 weeks, including the maintenance of liver-specific functions. On the other hand, when cultured at low cell-density, fetal hepatocytes underwent morphological modifications and acquired fibroblastic morphology. Since a switch from E-cadherin to vimentin expression accompanied these changes, we hypothesized the occurrence of epithelial-to-mesenchymal transition when fetal hepatocytes were cultured at low cell-density. Changes in gene expressionsuch as up-regulation of fibrosis-related geneswere also observed, suggesting that the low cell-density culture system promoted the acquisition of a profibrotic phenotype in cultured hepatocytes. The origin of fibrogenic cells in the liver is not well known, and the role of hepatocytes as a source of fibrogenic cells is controversial. Therefore, we hypothesized that hepatocytes undergoing epithelial-to-mesenchymal transition could have a central role in liver fibrosis as a source of fibrogenic cells. To conclude, the high cell-density culture system could be a useful model for in vitro studies requiring long-term cultures of hepatocytes, such as the development of pharmaceutical drugs and mechanisms of viral infections. The low cell-density culture system may provide additional insights into the origin of fibrogenic cells in the liver, thus contributing to the development of novel therapeutic approaches.