OBJECTIVETo establish a gene-modified embryonic stem (ES; E14.1-2) cell line with hepatoblast differentiation reporter genes, albumin (ALB) and cytokeratin 19 (CK19), labeled to facilitate study of their potential applicability as differentiated hepatoblasts.

METHODSTwo expression vectors were constructed, one with the ALB promotor driving the enhanced green fluorescent protein (EGFP) and anti-neomycin genes (pAlb-EGFP), and the other with the CK19 promotor driving the red fluorescence protein and anti-hygromycin genes (pCK19-hCD25-IRES-tdTOMATO). The linearized vectors were electroporated into the E14.1 line, and double reporter genes-modified ES cells (E14.1-2) were selected by neomycin and hygromycin. E14.1-2 hepatoblast differentiation was induced by exposure to growth factors (BMP4 and bFGF) and evidenced by embryoid body formation. Fluorescence-activated cell sorting (FACS) and reverse transcription-polymerase chain reaction (RT-PCR) were used to confirm whether differentiated cells were hepatoblast-like and to quantify the differentiation efficiency.

RESULTSThe pAlb-EGFP and pCK19-hCD25-IRES-tdTOMATO vectors were shown to specifically activate ALB and CK19 expression. The E14.1-2 cell line with labeled ALB and CK19 was established, and shown to have pluripotency by RT-PCR detection of pluripotent markers' expression, namely Oct4 and SSEA-1. After 22 days of induction, 21.27% of the differentiated hepatoblasts were detected by FACS as positive for ALB and CK19 expression.

CONCLUSIONSA gene-modified ES cell line was generated with hepatocyte differentiation reporter genes ALB and CK19 labeled. The differentiation of the resultant E14.1-2 line was technically simple to qualify and quantify, and will likely aid future studies of hepatoblast characteristics.