Monocytic differentiation of bone marrow-derived hematopoietic precursors controlled by mesenchymal stem cell in absence of exogenous hematopoitic growth factors

To study the hematopoiesis controlled by mesenchymal stem cell (MSC) in the absence of exogenous hematopoietic growth factors in vitro. MSCs were isolated and cultured in vitro, and the hematopoietic growth factors secreted by MSCs were detected with RT-PCR. Mononuclear cells from bone marrow were seeded in 6-well plates in which MSCs had been seeded as feeder cells. After culture for 3 weeks, cells in coculture were observed with wright's staining, immunocytochemisty and flow cytometry analysis to identify the lineage of hematopoietic cells. The results showed that SCF, Flt3 Ligand and M-CSF were detected in MSCs, but G-CSF and GM-CSF were not detected. In the coculture system, a number of round shape cells grew adherently to the spindle shape MSCs after coculture for 2 weeks. Wright's staining displayed that the round shape cells had abundant plasma and kidney-shaped or oval nucleus, some cells had typical monocytic morphology, and Flow cytometry analysis displayed that the CD45+ round shape cells were positive for CD14 and were negative for CD15, CD7, CD19, CD41 and glycoporin A. Our data suggested that hematopoietic precursors from bone marrow were able to differentiate into monocyte controlled by mesenchymal stem cells in vitro in absence of exogenous hematopoitic growth factors, the committed differentiation might be regulated by the hematopoietic growth factors secreted by MSCs, and the cell-cell contact might also contribute to the differentiation.