Hepatic myofibroblasts: a heterogeneous population of multifunctional cells in liver fibrogenesis.

Hepatic myofibroblasts constitute a heterogeneous population of highly proliferative, pro-fibrogenic, pro-inflammatory, pro-angiogenic and contractile cells that sustain liver fibrogenesis and then fibrotic progression of chronic liver diseases of different aetiology to the common advanced-stage of cirrhosis. These alpha-smooth muscle actin-positive myofibroblast-like cells, according to current literature, mainly originate by a process of activation and trans-differentiation that involves either hepatic stellate cells or fibroblasts of portal areas. Hepatic myofibroblasts can also originate from bone marrow-derived cells, including mesenchymal stem cells or circulating fibrocytes able to engraft chronically injured liver, as well as, in certain conditions, by a process of epithelial to mesenchymal transition involving hepatocytes and cholangiocytes. Hepatic myofibroblasts may have also additional crucial roles in modulating immune response and in the cross talk with hepatic progenitor (stem) cells as well as with malignant cells of either primary hepatocellular carcinomas or of metastatic cancers.