Patent ID: 7645610

Claim:
A method of culturing and expanding hepatic precursor cells in vitro comprising: a) isolating a population of cells from liver tissue obtained from a mammal, wherein said population of cells comprises stellate cells, hepatocytes, cholangiocytes, oval cells, Kupffer cells, sinusoidal endothelial cells and hepatic precursor cells; b) enriching said population of cells for hepatic precursor cells c) culturing said enriched population of cells in a culture medium comprising at least 50 μM of a guanine nucleotide precursor, or an analogue or derivative thereof, wherein said guanine nucleotide precursor suppresses asymmetric cell kinetics thereby allowing exponential growth and expansion of said hepatic precursor cells, and wherein said guanine nucleotide precursor is hypoxanthine, xanthine, or xanthosine; c) passaging said cultured hepatic precursors in the culture medium of step (b) for a period of time exceeding 50 culture passages under conditions such that the hepatic precursor cells show no evidence of neo-plastic cell transformation as determined by soft agar colony formation, wherein said hepatic precursor cells retain the ability to express characteristics of differentiated, nontransformed hepatocytes following transplantation, and wherein at least a portion of said cells or a portion of the progeny of said cells is capable of differentiating into hepatocytes.