Generation of adipose stromal cell-derived hepatic cells.

The demand for primary human hepatocytes to test the toxicity of new drug candidates and to develop cell therapies for liver disease far exceed the number of hepatocytes that can be isolated from donated tissues. Less than 700 whole livers per year are available for research applications. The ability to utilize nonhepatic progenitor cells, such as adipose stromal cells (ASCs), to generate derivatives that mimic primary human hepatocytes would enable the scale-up production of cell products for bioartifical liver-assist devices, cell therapy, and drug discovery applications. ASC hepatogenesis is a rapidly evolving field with improved protocols continually being reported in the literature. In this chapter, current and effective protocols for the expansion, hepatic differentiation, and functional characterization of ASC-derived hepatic cells are outlined. Two major features distinguish optimized methodologies: (a) cytokine-mediated "reprogramming" of mesenchymal ASCs to enable transdifferentiation into endodermal cell lineages, and (b) treatment with sequential media formulations containing factors/extracellular matrices that mimic the temporal expression profiles seen during fetal liver development. Criteria for success are acquisition of hepatic functional activities, such as albumin/urea production and p450 CYP activities, at levels that approach those observed in primary human hepatocyte controls.