Isolation from human fetal liver of cells co-expressing CD34 haematopoietic stem cell and CAM 5.2 pancytokeratin markers

Background/Aims: Ductal plate and bile duct cells in developing human liver express haemotopoietic stem cell markers, such as c-kit and CD34, in association with cytokeratin markers CAM 5.2 and CK 18. The identification for both bile ducts epithelial cells and hepatocytes and their possible reappearance as oval cells in the regenerating liver have generated much interest in their pluripotential capacities. This study aimed to isolate cells from human fetal liver that co-express haematopoietic stem cell and epithelial cell markers. Methods: Human fetal liver was harvested following legal termination of pregnancy at week 14–22. CD34+ mononuclear cells were isolated from liver cell suspensions with immunomagnetic beads. Immmunofluorescent staining, using anticytokeratin CAM 5.2 against CK 8 and 18, was performed on permeabilised CD34+ cells for cytomeetry and fluorescent microscopy. CD34+ cells were stained for other stem cell markers (HLA-DR, c-kit) and committed haematopoietic cell markers (CD33, CD38). Results: Approximately 0.9% (range 0.07–4.0%) of the mononuclear cells isolated were (CD34+) cells. The number of mononuclear cells isolated correlated with fetal liver weight (r=0.508). About 3–8% of these CD34+ cells stained for CAM 5.2. In addition, CD34+ cells were positive for HLA-DR, but only a small percentage was positive for c-kit. Staining for the committed haematological markers, CD33 and CD38, was consistently negative. Conclusion: This study describes an immunoaffinity method for the enrichment from human fetal liver of cells that co-express haematopoietic stem cell and epithelial cell markers. Such cellular subsets may correspond to pluripotential ductal plate and bile duct cells.