[Dexamethasone modifies development of human long-term bone marrow culture in dose dependent manner]

Dexter's long-term bone marrow cultures were performed to evaluate the effects of exponentially decreasing concentrations of dexamethasone (10(-2) M to 10(-8) M) on proliferation, differentiation and oxidative burst of the human bone marrow cells. High concentrations of dexamethasone show antiproliferative effect on stromal and haemopoietic cells. There was a small number of adipocytes and macrophages, with predominance of fibroblasts. Cultures, grown in lower concentration of dexamethasone (10(-4) M to 10(-7) M) consisted of a greater number of adipocytes and macrophages. The number of haematopoietic islands was increased and differentiation of haematopoietic cells was pronounced. The adipocytes proliferation was more pronounced, while their maturation was slowed down when low concentrations of dexamethasone were used. The size and the number of haematopoietic islands were reduced. Optimal concentration of dexamethasone for normal growth of both stromal and haematopoietic cells were between 10(-5) M and 10(-7) M. NBT reduction ability of myeloid and stromal cells increased using the higher concentrations of dexamethasone. However, only myeloid cells were NBT positive when lower concentrations were used. Dexamethasone acted as functional and maturational factor for oxidative burst of stromal, as well as myeloid haematopoietic cells.