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 α-fetoprotein (AFP), albumin (ALB), cytokeratins (CK) 7, and CK18, as well as the mesenchymal markers, such as α-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.