Fig. 6. Meso-endodermal phenotype in fetal liver cells. (a) Immunostaining of early P0 culture (7 days) with GFP lentiviral vector expression under TTR promoter (left, green color), filamentous vimentin (middle, red color) and merged image (on right) showing coexpression in cells of GFP and vimentin. (b) Similar findings in late P0 culture, with coexpression of GFP lentiviral vector under Alb promoter and filamentous vimentin, except for morphological alterations. (c) P7 culture with GFP expression under Alb promoter, filamentous -SMA expression (middle) and merged image showing cells with either or both properties (right). DAPI nuclear counterstain. Magnification: x200. (d) Summary of gene expression switches with quantitative RT-PCR showing mean fold-change in mRNA abundance in freshly isolated fetal liver cells (primary), early P0 culture (7 d) and multi-week P3 cultures. Alb, AFP, CK-19, E-cadherin, and HNF1 and HNF4 were expressed less in P0 and P3 cells, while HNF3 (FOXA1) expression reappeared. By contrast, expression of vimentin, -SMA, TGFβ1 and TGFβ2 and receptors, increased. Data were normalized against β2-microglobulin. An arbitrary baseline was assigned to HNF3.