G‐CSF Indirectly Induces Apoptosis of Osteoblasts During Hematopoietic Stem Cell Mobilization

The objective of this study was to explore the mechanism underlying osteoblast suppression in the process of hematopoietic stem cells mobilization induced by granulocyte colony‐stimulating factor (G‐CSF). The apoptosis of human and mouse osteoblasts was examined by detecting caspase 3. The levels of serum DKK1 and osteocalcin in the supernatant of co‐culture of mouse osteoblasts and mouse bone marrow nucleated cells were measured. The number of mouse osteoblasts co‐cultured with mouse bone marrow nucleated cells was measured and the osteocalcin mRNA level was also measured. The G‐CSF‐induced decrease in osteoblast function was partly due to the apoptosis of osteoblasts. There was no significant difference in the level of serum DKK1 in healthy donors before and 5 days after mobilization. The osteocalcin gene and protein expression was significantly different in co‐cultured osteoblasts with bone marrow nucleated cells treated with and without G‐CSF. Osteoblasts undergo apoptosis during mobilization and G‐CSF affects osteoblasts through bone marrow nucleated cells.