Effects of MBRI9901 (rhG-CSF) on γ-ray irradiated mice with bone marrow transplantation

To determine the efficacy of MBRI9901, a recombinant human granulocyte-colony stimulating factor (rhG-CSF) developed by Korea Green Cross cooperation (KGCC), we administrated MBRI9901 for 22 days to γ-ray irradiated and followed by bone marrow transplanted mice. We then examined the mortality of mice, neutrophil numbers, and the ratio of myeloid to erythroid in bone marrow on days 9, 13, 18, 22, and 26 after the drug administration. We also performed the chromosome aberration and supravital micronucleus assay at the same time points to determine the potential effects of MBRI9901 on mutational events induced by γ-ray irradiation. Our results showed that mortality was apparently reduced by MBRI9901, and the number of peripheral neutrophils in MBRI9901-treated group recovered rapidly. The ratio of myeloid to erythroid in bone marrow also rapidly recovered in MBRI9901-treated group compared to control group. Frequencies of micronucleated reticulocytes in MBRI9901-treated group were significantly lower than in control group suggesting a clear anti-micronucleated process of MBRI9901 on abnormal erythrogenesis. However, MBRI9901 did not have an effect on the process of chromosome aberration. The above data strongly suggest that MBRI9901 may stimulate the differentiation of myeloid and maintain the level of peripheral neutrophil after bone marrow transplantation in γ-ray irradiated mice. It also has some effects on the escape from abnormal erythrogenesis induced by γ-ray irradiation.