Method for preparing functional hepatic progenitor cells or hepatic cells, or functional small intestinal epithelial progenitor cells or small intestinal epithelial cells

A method for preparing functional hepatic progenitor cells or functional hepatic cells, or functional small intestinal epithelial progenitor cells or functional small intestinal epithelial cells, the method comprising the step of culturing an isolated cell population comprising hepatic progenitor cells or hepatic cells, or small intestinal epithelial progenitor cells or small intestinal epithelial cells in the presence of 0.1 to 100 μg/ml puromycin and 5 to 15 mg/ml ammonia,

• wherein the hepatic progenitor cells or hepatic cells, or the small intestinal epithelial progenitor cells or small intestinal epithelial cells do not comprise an exogenous resistance gene for the antibiotic.