A method of treating liver-based inborn, metabolic deficiencies is disclosed by treatment of an individual, such as a patient suffering from liver-based inborn, metabolic deficiencies, with human progenitor or stem cells, a cell population or their progeny. The cells used in the treatment have the following characteristics. They are positive for vimentin, α-smooth muscle actin (ASMA), and for at least one mesenchymal marker such as CD90, CD29, CD73, and CD44. They are positive for at least one hepatocyte marker such as albumin, alpha-fetoprotein, alpha-1 antitrypsin, HNF-4 and MRP2 transporter. They express at least one hepatocyte-like property or function such as G6P, CYP1B1, CYP3A4, TDO, TAT, GS, GGT, CK8, and EAAT2. They are negative for at least one marker such as cytokeratin-19, CD45, CD34, CD49f, CD133, HLA-DR, and CD117. They have mesenchymal-like morphology. They originate from human adult liver cells.