Human hepatic stem cells from fetal and postnatal donors

TLDR

Human hepatic stem cells (hHpSCs) are pluripotent precursors of hepatocytes and biliary cells found in ductal plates of fetal livers and in the Canals of Hering in adult livers. The study proposes hHpSCs as candidates for liver cell therapies. hHpSCs are isolated as EpCAM⁺ cells comprising 0.5–2.5 % of liver parenchyma, are ~9 µm, express cytokeratins 8, 18, 19, CD133/1, telomerase, CD44H, claudin 3, weak albumin, are negative for AFP, ICAM‑1, and other lineage markers, and can differentiate into hepatoblasts on STO feeders, forming cord‑like colonies with up‑regulated AFP, P4503A7, and ICAM‑1. They exhibit robust self‑renewal with >150 doublings and a ~36‑hour doubling time in serum‑free medium, require paracrine support from hepatic stellate cells or angioblasts, and when transplanted into NOD/SCID mice generate mature human liver tissue expressing species‑specific proteins.

Abstract

Human hepatic stem cells (hHpSCs), which are pluripotent precursors of hepatoblasts and thence of hepatocytic and biliary epithelia, are located in ductal plates in fetal livers and in Canals of Hering in adult livers. They can be isolated by immunoselection for epithelial cell adhesion molecule–positive (EpCAM+) cells, and they constitute ∼0.5–2.5% of liver parenchyma of all donor ages. The self-renewal capacity of hHpSCs is indicated by phenotypic stability after expansion for >150 population doublings in a serum-free, defined medium and with a doubling time of ∼36 h. Survival and proliferation of hHpSCs require paracrine signaling by hepatic stellate cells and/or angioblasts that coisolate with them. The hHpSCs are ∼9 μm in diameter, express cytokeratins 8, 18, and 19, CD133/1, telomerase, CD44H, claudin 3, and albumin (weakly). They are negative for α-fetoprotein (AFP), intercellular adhesion molecule (ICAM) 1, and for markers of adult liver cells (cytochrome P450s), hemopoietic cells (CD45), and mesenchymal cells (vascular endothelial growth factor receptor and desmin). If transferred to STO feeders, hHpSCs give rise to hepatoblasts, which are recognizable by cordlike colony morphology and up-regulation of AFP, P4503A7, and ICAM1. Transplantation of freshly isolated EpCAM+ cells or of hHpSCs expanded in culture into NOD/SCID mice results in mature liver tissue expressing human-specific proteins. The hHpSCs are candidates for liver cell therapies.