Rat granulocyte colony-forming unit (CFU-G) assay for the assessment of drug-induced hematotoxicity.

To assess the drug-induced hematotoxicity to granulocyte progenitors, we established a modified colony-forming assay using rat bone marrow cells (BMCs). In the presence of various colony-stimulating factors (CSFs), rat BMCs were disseminated on methylcellulose at a concentration of 1.3 x 10(4) cells/cm(2) (5 x 10(4) cells/0.5 ml/well in a 12-well plate). Mouse granulocyte-macrophage colony-stimulating factor (mGM-CSF) stimulated the formation of almost all macrophage colonies. Human granulocyte colony-stimulating factor (hG-CSF) alone or in combination with mouse interleukin-3 (mIL-3) did not significantly effect on the number of rat colony-forming units in culture (CFU-C). When BMCs were seeded at 5.2 x 10(4) cells/cm(2) (5 x 10(5) cells/1 ml/dish in a 35-mm dish), hG-CSF increased the number of the colonies in a dose-dependent manner, and resulted in about 50 colonies at 50 ng/ml. The constituent cells of the colonies were identified as neutrophils. Under these conditions, the effects of 5-fluorouracil (5-FU) on granulocyte colony-forming units (CFU-G) were examined in rats and mice. The inhibitory effect of 5-FU on rat CFU-G was similar to the effect on mouse CFU-G. These results indicate that the rat CFU-G induced by hG-CSF is capable of being used for the evaluation of drug-induced hematotoxicity.