A pivotal role of bone remodeling in granulocyte colony stimulating factor induced hematopoietic stem/progenitor cells mobilization

The majority of hematopoietic stem/progenitor cells (HSPCs) reside in bone marrow (BM) surrounded by a specialized environment, which governs HSPC function. Here we investigated the potential role of bone remodeling cells (osteoblasts and osteoclasts) in homeostasis and stress-induced HSPC mobilization. Peripheral blood (PB) and BM in steady/mobilized state were collected from healthy donors undergoing allogeneic transplantation and from mice treated with granulocyte colony stimulating factor (G-CSF), parathyroid hormone (PTH), or receptor activator of nuclear factor kappa-B ligand (RANKL). The number and the functional markers of osteoblasts and osteoclasts were checked by a series of experiments. Our data showed that the number of CD45-Ter119- osteopontin (OPN)+ osteoblasts was significantly reduced from 4,085 +/- 135?cells/femur on Day 0 to 1,032 +/- 55?cells/femur on Day 5 in mice (P?=?0.02) and from 21.38 +/- 0.66 on Day 0 to 14.78 +/- 0.65 on Day 5 in healthy donors (P?