Abstract: Objective To isolate and cultivate mouse hepatic progenitor cells (mHPCs) from E14.5 mouse fetal liver in vitro and induce mHPCs differentiation into cholangiocytes. Methods Isolation of mHPCs from mouse fetal liver wasbased on the cell surface antigendelta-like protein 1/preadipocyte factor 1 (Dlk/Pref-1) by a fluorescence-activated cell sorter (FACS). Then mHPCsisolated wereco-cultured with/without mouse embryonic fibroblasts (MEFs) by using Transwell. The cellantigen alpha-fetoprotein (AFP), albumin (ALB) and cytokeratin19 (CK19) expression in fresh isolatedDLK1+cells or co-cultured for 4 days and 6 days were observed with immunocytochemical method. Results When co-cultured with MEFs, the division and proliferation were observed in most of DLK1+ cells andgrape-like aggregation was formed. Cells began to adhere to growth and began to become spindle-shaped on 4th day.TheDLK1+cells isolated freshly by FACS were expressed AFP and low levels of ALBbut not expressed CK19. But, these cells expressed CK 19and weak expression of ALB on4thday.In addition, the expression of CK19increased and the expression of ALB almost not detected on 6th day. Conclusion Most of Dlk1+ cells, isolated from E14.5 fetal livers by FACS, wereprovedto be mHPCs. Furthermore, these cells can proliferate quickly and differentiate into cholangiocytes by co-culture with MEFs.

Key words: hepatic progenitor cells, mouse embryonic fibroblasts, chlangiocytes, fluorescence-activated cell sorter