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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.

The transmembrane protein CD133 is expressed on somatic stem cells of various adult human tissues. To investigate whether human corneal stroma also contains CD133-expressing cells and to analyze their functional features, stromal cells were isolated by collagenase digestion, immunophenotyped, and transferred to different culture systems to determine their stem cell properties as well as their differentiation potentials. For comparison, the embryonic keratocyte cell line EK1.Br, the dermal stromal cell line NHDF, and stromal cells of diseased corneas were studied. On average, 5.3% of the normal stromal cells expressed the stem cell marker CD133 and 3.6% co-expressed CD34. Expression of CD133 but not CD34 was also demonstrated for EK1.Br cells, whereas NHDF cells were negative for both markers. Further analysis of CD133(+) normal corneal cells revealed that a significant proportion displayed a monocytic phenotype with co-expression of CD45 and CD14. In diseased corneas, up to 26.8% of the stromal cells showed expression of CD133, and virtually all CD133(+) cells co-expressed CD14 but not CD45. Moreover, using a standard clonogenic assay, normal stromal cells had the capacity to form colonies of the macrophage lineage. These colonies could be further differentiated into lumican-expressing keratocytes. Our data suggest that the human corneal stroma harbors CD133(+) monocytic progenitor cells, which possess the potential to differentiate into the fibrocytic lineage. Thus, CD133(+) /CD45(+) /CD14(+) cells might represent stromal repair cells that differentiate into keratocytes via a CD133(+)/CD45()/CD14(+) intermediate stage. The findings from our study may shed new light on regenerative processes of the human corneal stroma.

Recent studies have shown that in response to vascular damage or ischemia, bone marrow-derived endothelial progenitor cells (EPCs) are recruited into the circulation. To investigate whether antihypertensive treatment has an influence on the number of circulating EPCs, patients with essential hypertension were treated either with the angiotensin receptor antagonist telmisartan, the calcium channel blocker nisoldipine, or their combination for 6 weeks. At baseline and after 3 and 6 weeks of treatment, EPCs were identified and quantified by fluorescence-activated cell sorting (FACS) analysis and by their capacity to generate colony-forming units of the endothelial lineage (CFU-EC) in a methylcellulose-based assay. During treatment, patients in the nisoldipine groups, but not in the telmisartan group, showed a significant mobilization of EPCs, which in part had the capacity to generate large-sized colonies comprising more than 1,000 cells. Moreover, a remarkable correlation between the number of CFU-EC and the number of circulating CD133(+)/CD34(+)/CD146(+) cells was observed, thereby providing strong evidence that cells with this phenotype represent functional EPCs. No correlation was found between the numbers of CFU-EC and the blood pressure levels at any time point during the treatment. Hence, nisoldipine-induced mobilization of EPCs might represent a novel mechanism by which this antihypertensive compound independently of its blood pressure-lowering effect contributes to vasoprotection in patients with essential hypertension.

Background/aims: Recent studies indicate that after transplantation, circulating bone marrow-derived stem cells migrate into the liver and contribute to liver regeneration. Whether such cells are actively recruited from the bone marrow for liver repair remains to be determined. In this regard, we investigated whether liver resection leads to a release of stem cell marker-positive (+) cells into the peripheral circulation., Methods: Peripheral blood samples from 11 living liver donors were analyzed by flow cytometry one day before and 12h after partial hepatectomy (PH) using antibodies against CD133, CD34, CD45, CD14, c-kit, bcrp-1. Immunomagnetic separation was performed to select CD133+ cells for functional assays in vitro., Results: A significant increase in the percentage of CD133+ cells could be demonstrated in all donors studied. Unexpectedly, virtually all CD133+ cells coexpressed CD45 and CD14, whereas only a small subset expressed CD34. No significant staining was observed for c-kit and bcrp-1. In culture, immunoselected CD133+ cells displayed characteristics of myelomonocytic precursors. In addition, enriched CD133+ generated an adherent cell population that expressed CK8, alpha-fetoprotein, and human albumin., Conclusions: PH induces mobilization of a distinct population of myelomonocytic progenitor cells, which have hepatic differentiation potential in vitro, and might play a role in liver regeneration after PH in humans.