[Phenotypical and Biological Characteristics of Human Fetal Marrow and Liver Mesenchymal Stem Cells]

There has been an increasing interest in recent years in the stromal cell system. The stroma is a complex tissue, composed of a number vascular and connective tissue cell types including endothelial cells, adipocytes, smooth muscle cells, osteogenic cells, and stromal cells. The marrow mesenchymal stem cells are capable of self-renewal and differentiate into various connective tissue lineages including bone, cartilage, tendon, muscle, fat, and marrow stroma. Recently, techniques for the isolation of adult bone marrow-derived human and animal mesenchymal stem cells have been described, as well as the methods to directing their differentiation into osteogenic, chondrogenic, tendogenic, myogenic, adipogenic, and marrow stromal lineages. But there is no report about the fetal bone marrow- and liver-derived mesenchymal stem cells. Are they the same or not? In our assay, human fetal mesenchymal stem cells from 4 - 5 months old human fetal bone marrow and liver low-density mononuclear cells were cultured, and the cell cycle, immunophenotype and ex vivo expansion properties were studied. Results showed that the mesenchymal stem cells from fetal liver and fetal bone marrow were similar in morphology, growth character and immuno-phenotypes, but the liver mesenchymal cells manifested higher ability to support hematopoiesis than the marrow-derived mesenchymal cells. This study demonstrates that adherent fetal marrow- and liver-derived cells cultured in the absence of differentiation stimulus gave rise to a population of cells with phenotypical features of mesenchymal stem cells, and should be enough to sustain a steady supply of low differentiated cells upon proliferation.