Response of myelodysplastic syndrome bone marrow cells to multiple cytokine stimulation in liquid cultures: an in situ hybridization study.

BACKGROUND AND OBJECTIVE Myelodysplastic syndrome progenitor cells can be grown and expanded in long term bone marrow liquid cultures in the presence of multiple cytokines. In this study we investigated the pattern of differentiation and response to growth factors in six cases of myelodysplastic syndrome (MDS) with well-defined cytogenetic abnormalities by means of conventional cytogenetics and fluorescence in situ hybridization (FISH). METHODS Bone marrow cells were grown in stroma-free liquid cultures in the presence of SCF, IL-3, IL-6 and GM-CSF. RESULTS IN three cases a CFU-GM expansion comparable to normal controls was observed, together with a decrease or increase of cells with abnormal karyotype. Two cases showed no response to growth factor stimulation, morphological signs of terminal myeloid differentiation and increase (one case) or decrease (one case) in the percentage of abnormal FISH signals along the cultures. In one additional case, while CFU-C expansion was present, clearcut leukemic transformation was observed in the culture, together with a sharp decrease in the percentage of abnormal FISH signals, indicating a leukemic transformation of MDS progenitor cells with a normal karyotype. INTERPRETATION AND CONCLUSIONS Our data indicate that FISH analysis is generally a poor indicator of clonality in MDS; nevertheless, determining the kinetics of cytogenetically abnormal clones in liquid bone marrow cultures may provide insight as to the growth abnormalities of MDS progenitor cells and may be useful prior to in vivo growth factor administration.