Heterogeneity in predisposition of hepatic cells to be induced into pancreatic endocrine cells by PDX-1

Figure 2 In situ immunostaining analysis of PDX-1⁺HepG₂ cells in culture and after transplantation into nude mice. Representatives are shown (original magnification 200×, unless otherwise stated). Anti-PDX-1 fluorescence stains cultured PDX-1⁺HepG₂ cells (B), compared to 24-wk human fetal pancreatic islets (A). The ectopically expressed PDX-1 protein locates mainly within nuclear region (C, 400×). Parental HepG₂ cells serve as a negative control (D). Anti-insulin fluorescence immunostaining indicates positive staining in human islet positive control (E) but not in PDX-1⁺HepG₂ cells (F). H&E staining reveals implanted PDX-1⁺HepG₂ cells in section of kidney (G, 100×), indicating that these cells infiltrated into nephric tissues and underwent proliferation. Anti-human nuclei antibody staining confirmed that these cells were of human origin (H, green cells). Anti-PDX-1 staining of mice kidney sections showed consistent expression of PDX-1 transgene in these implanted PDX-1⁺HepG₂ cells (I), but insulin expression was absent (J).