Hepatic progenitors comprise two populations of human hepatic stem cells,
primitive and proximal hepatic stem cells, and two populations of
committed progenitors, one for biliary cells and one for hepatocytes.
Human primitive hepatic stem cells are a very small fraction of the liver
cell population and give rise to proximal hepatic stem cells constituting
a much larger fraction of the liver. Human proximal hepatic stem cells
give rise to biliary and hepatocyte committed progenitors. Primitive and
proximal stem cells are the primary stem cells for the human liver. Human
primitive hepatic stem cells may be isolated by immunoselection from
human livers or culturing human liver cells under conditions which select
for a human primitive hepatic stem cell. Proximal hepatic stem cells may
be isolated by immunoselection, or by culturing human liver cells under
conditions which include a developmental factor. Proximal hepatic stem
cells may also be isolated by culturing colonies comprising a primitive
hepatic stem cell under conditions which include a developmental factor.
Resulting compositions may be used for treating liver disorders and for
producing bioartificial organs.