Bone marrow fibroblasts-conditioned medium regulates the proliferation of leukemic cells

The effect of normal human bone marrow fibroblasts-conditioned medium (BMF-CM) was studied on the proliferation of K562 cells, and on leukemic cells from patients with acute myelocytic leukemia at the time of diagnosis and chronic myelogenous leukemia (CML) at chronic phase. BMF-CM was obtained from normal human bone marrow fibroblasts by using long-term liquid cultures. BMF-CM suppressed the proliferation of K562 cells and leukemic cells from patients with undifferentiated type of leukemia (M1 in FAB classification). However it stimulated the proliferation of leukemic cells from patients with differentiated type of leukemia (M2 in FAB classification), and it slightly stimulated that from patients with CML. These results suggest that normal human BMF regulate the proliferation of leukemic cells in their various stages of differentiation in the bone marrow by releasing a humoral factor.