Protection of mouse bone marrow by Si-WU-Tang against whole body irradiation.

The ability of Si-Wu-Tang to eliminate bone marrow damage after radiation was assessed using both a clonogenic assay (survival of colony forming units spleen--CFUs) of stem cell survival and a hematopoietic functional assay including the changes of hemograms and hematocrit. Cell survival curves and dose-response curves for radiation alone and Si-Wu-Tang administration with radiation were constructed over the dose range of 1 to 9 Gy. Si-Wu-Tang was given 7 days before irradiation at a consecutive fractionated dose of 20 mg/20 g body weight. The radioresistance of stem cells treated by Si-Wu-Tang was higher than that of those treated by irradiation alone. However, the anti-radiation effect of leukocytes was not as significant as that of erythrocytes, thrombocytes and hematocrit. These data suggest that the anti-radiation effect by Si-Wu-Tang is dependent on dose and will be less after 4 Gy irradiation. Hemograms with a short turnover period, such as leukocytes, may be less affected after Si-Wu-Tang administration.