AIM:To test the hypothesis that liver cirrhosis is associated with mobilization of hematopoietic progenitor cells.METHODS:Peripheral blood samples from 72 patients with liver cirrhosis of varying etiology were analyzed by flow cytometry.Identified progenitor cell subsets were immunoselected and used for functional assays in vitro.Plasma levels of stromal cell-derived factor-1 (SDF-1)were measured using an enzyme linked immunosorbent assay.RESULTS:Progenitor cells with a CD133~+/CD45~+/ CD14~+ phenotype were observed in 61% of the patients.Between 1% and 26% of the peripheral blood mononuclear cells (MNCs) displayed this phenotype.Furthermore,a distinct population of c-kit~+ progenitor cells (between 1% and 38 % of the MNCs) could be detected in 91% of the patients.Additionally,18% of the patients showed a population of progenitor cells (between 1% and 68% of the MNCs) that was characterized by expression of breast cancer resistance protein-1.Further phenotypic analysis disclosed that the circulating precursors expressed CXC chemokine receptor 4,the receptor for SDF-1.In line with this finding,elevated plasma levels of SDF-1 were present in all patients and were found to correlate with the number of mobilized CD133+ progenitor cells.CONCLUSION:These data indicate that in humans,liver cirrhosis leads to recruitment of various populations of hematopoietic progenitor cells that display markers of intrahepatic progenitor cells.