Hepatic Stem Cells and Hepatoblasts: Identification, Isolation, and Ex Vivo Maintenance

Publisher Summary This chapter discusses hepatic stem cells (HpSCs) and provides protocols on HpSCs, especially human hepatic stem cells (hHpSCs). It also includes development of a serum-free, hormonally defined medium (HDM), preparation of tissue extracts enriched in extracellular matrix, and methods to design biodegradable, polylactide scaffoldings or microcarriers in ways appropriate for progenitors and use of bioreactors. There has been recognition that the epithelial–mesenchymal relationship is lineage dependent. Epithelial stem cells are partnered with mesenchymal stem cells, and their differentiation is co-ordinate. In the liver, the lineages begin with the HpSCs paired with their mesenchymal partners and angioblasts that interact with multiple forms of paracrine signals. These two give rise to descendents in a stepwise, lineage-dependent fashion and their descendents remain in a partnership throughout differentiation. Tissue engineering involves the mimicking of the liver's epithelial–mesenchymal relationship with recognition of the lineage-dependent phenomena. Serum-free, HDM have been found to select for parenchymal cells even when the cells are on tissue culture plastic. Tissue-specific gene expression is improved in cultures under serum-free conditions and especially with serum-free medium supplemented with only the specific hormones needed to drive expression of a given tissue-specific gene.