Blast colony forming cell-binding capacity of bone marrow stroma from myelodysplastic patients

A specific stroma function can be quantitatively assessed by counting the stroma-adherent blast cell colonies (CFU-BL) that are formed from normal plastic nonadherent mononuclear bone marrow cells (PNAMNC) after a short-term coincubation ("panning") with the preformed stromal layer. In order to obtain information of stroma function in myelodysplasia (MDS), the "CFU-BL-binding capacity" of stroma from normal bone marrow and from patients with MDS were compared. Stromal cell cultures were established from mononuclear bone marrow cells in microplate cultures cultured with or without 10(-6) M hydrocortisone. CFU-BL-binding capacity was studied by counting blast colonies seven days after panning, and the results were expressed as CFU-BL/10(3) PNAMNC. Normal marrow stromal layers bound CFU-BL only if they were cultured with hydrocortisone, while MDS stromal layers also bound CFU-BL in the absence of hydrocortisone. For further studies of the function of MDS stroma, the effect of growth factors (stem cell factor [SCF], G-CSF, interleukin 3 [IL-3] and their combinations) on CFU-BL binding by normal or MDS stroma has also been compared. Twenty-hour incubation of the stromal layers with a standard dose (100 ng/ml) of various hemopoietic growth factors (IL-3 alone or in combination with SCF, G-CSF alone or in combination with SCF) did not have any effect on CFU-BL binding by normal marrow stroma, but increased the CFU-BL binding by stromal layers from MDS bone marrow. These findings suggest that although stromal microenvironment in MDS is capable of supporting hemopoiesis, bone marrow stroma from MDS patients differs in some characteristics from the normal stroma.