Hepatocyte generation from pancreatic acinar cell lines

Abstract

The transdifferentiation of pancreatic acinar cells towards hepatocytes is an event that occurs in vitro and in vivo in rodents. The B-13 cell line is a model for studying this phenomenon in vitro; it readily transdifferentiates into hepatocyte-like cells in response to glucocorticoids such as dexamethasone (DEX). The transdifferentiation event is dependent on a transient suppression of Wnt signalling followed by induction of Serine/threonine-protein kinase 1(SGK1) via interactions with the glucocorticoid receptor. This thesis has aimed to further explore pancreatic to hepatic transdifferentiation, using the B-13 cell as a model and also investigated the phenomenon in human cells. As hepatic stellate cells are involved in liver regeneration and may support the progenitor niche in liver, coculture experiments were conducted to assess their effects on B-13 transdifferentiation. Transdifferentiation was enhanced in cocultures and found to be dependent on cell-cell interaction that resulted in further suppression of the Wnt signalling pathway by myofibroblasts. B-13 transdifferentiation was shown to be able to take place in vivo for the first time; cells were found to engraft only into the liver and pancreas of NOD/SCID mice. Interestingly, only cells within the liver environment showed expression of hepatocyte-specific genes. B-13 cells were also cultured in 3D bioreactor devices where they transdifferentiated into functional hepatocyte-like cells with gene expression at levels comparable to primary rat hepatocytes. Elucidating the mechanisms involved during B-13 transdifferentiation will support the isolation of an equivalent human pancreatic cell. Studies with a human cell line and primary exocrine cells demonstrated that glucocorticoids also induce hepatocyte-gene expression, and thus the generation/isolation of a human equivalent to the B-13 is a realistic goal.