CD271 identifies functional human hepatic stellate cells, which localize in pen-sinusoidal and portal areas in liver after partial hepatectomy

Background aims. Hepatic stellate cells (HSCs) are liver-resident mesenchymal cells involved in essential processes in the liver. However, knowledge concerning these cells in human livers is limited because of the lack of a simple isolation method. Methods. We isolated fetal and adult human liver cells by immunomagnetic beads coated with antibodies to a mesenchymal stromal cell marker (CD271) to enrich a population of HSCs. The cells were characterized by cell cultivation, immunocytochemistry, flow cytometry, reverse-transcription polymerase chain reaction and immunohistochemistry. Cells were injected into nude mice after partial hepatectomy to study in vivo localization of the cells. Results. In vitro, CD271(+) cells were lipid-containing cells expressing several HSC markers: the glial fibrillary acidic protein, desmin, vimentin and alpha-smooth muscle actin but negative for CK8, albumin and hepatocyte antigen. The cells produced several inflammatory cytokines such as interleukin (IL)-6, IL-1A, IL-1B and IL-8 and matrix metalloproteinases MMP-1 and MMP-3 and inhibitors TIMP-1 and TIMP-2. In vivo, fetal CD271(+) cells were found in the pen-sinusoidal space and around portal vessels, whereas adult CD271(+) cells were found mainly in the portal connective tissue and in the walls of the portal vessels, which co-localized with alpha-smooth muscle actin or desmin. CD271(-) cells did not show this pattern of distribution in the liver parenchyma. Conclusions. The described protocol establishes a method for isolation of mesenchymal cell precursors for hepatic stellate cells, portal fibroblasts and vascular smooth muscle cells. These cells provide a novel culture system to study human hepatic fibrogenesis, gene expression and transcription factors controlling HSC regulation.