Conversion of immortal liver progenitor cells into pancreatic endocrine progenitor cells by persistent expression of Pdx‐1

The conversion of expandable liver progenitor cells into pancreatic beta cells would provide a renewable cell source for diabetes cell therapy. Previously, we reported the establishment of liver epithelial progenitor cells (LEPCs). In this work, LEPCs were modified into EGFP/Pdx‐1 LEPCs, cells with stable expression of both Pdx‐1 and EGFP . Unlike previous work, with persistent expression of Pdx‐1, EGFP/Pdx‐1 LEPCs acquired the phenotype of pancreatic endocrine progenitor cells rather than giving rise to insulin‐producing cells directly. EGFP/Pdx‐1 LEPCs proliferated vigorously and expressed the crucial transcription factors involved in beta cell development, including Ngn3 , NeuroD , Nkx2.2 , Nkx6.1 , Pax4 , Pax6 , Isl1 , MafA and endogenous Pdx‐1 , but did not secrete insulin. When cultured in high glucose/low serum medium supplemented with cytokines, EGFP/Pdx‐1 LEPCs stopped proliferating and gave rise to functional beta cells without any evidence of exocrine or other islet cell lineage differentiation. When transplanted into diabetic SCID mice, EGFP/Pdx‐1 LEPCs ameliorated hyperglycemia by secreting insulin in a glucose regulated manner. Considering the limited availability of beta cells, we propose that our experiments will provide a framework for utilizing the immortal liver progenitor cells as a renewable cell source for the generation of functional pancreatic beta cells. J. Cell. Biochem. 104: 224–236, 2008. © 2007 Wiley‐Liss, Inc.