Clinical significance of human bone marrow stromal cell colonies in acute leukemias

Human bone marrow-derived fibroblastoid colony-forming cells (CFU-F) and adipocyte colonies in 36 patients with acute leukemia were studied, and were serially analysed at different clinical stages. At untreated stage, CFU-F number in acute lymphoblastic leukemia (ALL) was lower than that in acute non-lymphoblastic leukemia (ANL). In ANLs, CFU-F number in M1 was lower than that in M2. Adipocyte colonies were frequently developed at regenerating and relapsing stages, but rarely at untreated and remission stages. The adipocyte colony formation did not correlate with any of CFU-F number, marrow cellularity nor number of leukemic cells, but might be associated with hemopoietic regeneration. The favorable prognosis was associated with normal CFU-F number and with adipocyte colony formation at regenerating or bottom stage. As adipocytes in marrow samples were completely removed before cultures, adipocyte colony was probably originated from preadipocytes. Thus, our results suggest that adipocyte precursor cells increase in regenerating marrow and that they are essential in active hemopoiesis.