Plasticity in the adult rat pancreas: transdifferentiation of exocrine to hepatocyte-like cells in primary culture.

Under certain experimental conditions, hepatocytes can arise in the pancreas. It has been suggested that the pancreas retains a source of hepatocyte progenitor cells. However, such cells have not been yet identified in the adult pancreas. We describe here the transdifferentiation of primary rat pancreatic exocrine cells into hepatocyte-like cells during 5 days of tissue culture in the presence of dexamethasone (DX). Using reverse-transcription polymerase chain reaction and immunocytochemistry, it was observed that DX treatment induced albumin RNA and protein expression in the cells. Coexpression of albumin and amylase, and the absence of cell proliferation, demonstrated a direct transdifferentiation of acinar cells to hepatocytic cells. CCAAT enhancer-binding protein-ss protein, a liver-enriched transcription factor that is considered to be the master switch in pancreatohepatic transdifferentiation, and alpha-fetoprotein were markedly upregulated in the cells after treatment with DX. We compared transcriptional profiles of freshly isolated exocrine cells and DX-treated cells using oligonucleotide microarrays and found that multiple liver-specific genes are induced along with albumin, and that certain pancreatic genes are downregulated in the DX-treated cells. In conclusion, these observations support the notion of plasticity in the adult pancreas and that exocrine cells can be reprogrammed to transdifferentiate into other cell types such as hepatocytes.