Abstract: Immortalized primary adult and fetal human cells are provided that express a functional telomerase catalytic subunit from a nucleic acid sequence encoding the hTERT gene. The telomerase-immortalized human cells can be maintained in culture for at least 35 population doublings without developing a transformed phenotype, and while continuing to express proteins associated with the primary differentiated cell type. The invention is also directed to immortalized, non-transformed cell lines derived from primary human cells that express a functional telomerase catalytic subunit and to their use for transplantation to patients with hepatic disease. The invention also is directed to an improved biologic extracorporeal liver support device wherein the improvement is the use of telomerase-immortalized hepatocytes incorporated onto the scaffolding of the cell colonization chamber and use of the improved device for treating symptoms of patients with hepatic disease.