The existence of epithelial-to-mesenchymal cells with the ability to support hematopoiesis in human fetal liver

The fetal liver is the major hematopoietic organ during mid-gestation, and it is also a source of stem cells that exist in a complex environment. In this study, we isolated a population of actively replicating cells with the characteristic of the epithelial-to-mesenchymal transition (EMT) from fetal liver. These cells were identified with the epithelial markers, including alpha-fetoprotein (AFP), albumin (ALB), cytokeratins (CK) 7, and CK18. as well as the mesenchymal markers, such as alpha-smooth muscle actin (ASMA), CD29, CD44, CD49, CD54, collagen I and osteopontin (OPN). Furthermore, they also expressed some hematopoiesis-related genes. In addition, the cell population had the ability to retain hematopoietic stem cells (HSCs) in an undifferentiated state in vitro during cytokine-stimulated proliferation. These results provide an insight about early human liver development and may also help to understand hematopoiesis in the fetal liver. (C) 2005 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.