Changed homing of hemopoietic precursor cells after long-term treatment with parathyroid hormone.

Changes in the capacity of hemopoietic stromal microenvironment to promote homing of hemopoietic stem cells from different hierarchical compartments were evaluated in mice treated with parathyroid hormone by determining their 24-h precipitation factor. This parameter did not change for splenic short-living hemopoietic stem cells (splenic CFU) and considerably decreased for the bone marrow of mice treated with parathyroid hormone. For earlier long-living hemopoietic stem cells (cells forming the cobblestone area on day 28) the precipitation factor after injections of parathyroid hormone did not change in the bone marrow and decreased in the spleen. These data suggest that parathyroid hormone decreases the efficiency of homing of short-living hemopoietic stem cells in the bone marrow.