Differential secretion of stimulatory-inhibitory CFU-GM activity by stromal cells from different compartments of mouse bone femur.

We have recently reported the beneficial effect of low oxygen concentration on the growth of fibroblast colony-forming units (CFU-F) isolated from the shaft of the femur (fraction 1), the endosteum (fraction 2), and the compact bone (fraction 3). We now report that the conditioned medium obtained from the CFU-F in the same experiments exhibited stimulatory activity from the compact bone while expressing inhibitory activity from the femoral shaft and endosteum for granulocyte-macrophage CFU (CFU-GM). These data support the presence of a spatial regulatory role for fibroblast-like cells within compartments of mouse bone for CFU-GM.