Functional comparison of bone marrow-derived liver stem cells: selection strategy for cell-based therapy.

Several distinct subpopulations of bone marrow-derived liver progenitor cells were recently described. However, there is inadequate information comparing these subpopulations from a liver-function point of view. This study was undertaken to compare two subpopulations of liver progenitors: beta(2)-microglobulin (beta(2)m)-negative/Thy-1-positive cells, and liver progenitors obtained from the non-adherent cell fraction after a panning procedure. The cells were cultured under several conditions including high- and low-dose hepatocyte growth factor, various cellular densities, and different media. Growth characteristics, liver-specific metabolic capacity, and liver regeneration-associated gene expression were studied. Both isolation procedures yielded cells that produced albumin and metabolized ammonia into urea. The study demonstrated that the beta(2)m-negative/Thy-1-positive cell fraction metabolized ammonia into urea more efficiently and produced a superior amount of albumin compared with the panned cell fraction. The beta(2)m-negative/Thy-1-positive cell fraction could be optimal for the development of novel cell-based treatment strategies for congenital or acquired liver diseases.