Greater sparing of stromal progenitor cells than of haemopoietic stem cells in gamma-irradiated mouse marrow using low dose-rates.
The Do value for fibroblastoid colony-forming units in mouse bone-marrow increased from 1.7 Gy using gamma-rays at 4.2 Gy/minute, to 2.6 Gy at 4.5 cGy/minute. In contrast, the sensitivity of bone-marrow stem cells was very little changed (Do approximately equal to 0.9 Gy). At 7.5 Gy acute single dose, the dose sparing achieved for CFU-F using 4.5 cGy/minute was a factor of 1.4, in between the values reported for lung of 1.8 and for haemopoiesis of 1.2. Although the role of CFU-F in the haemopoietic environment has not been established, the content of CFU-F can predict the ability of irradiated marrow to sustain haemopoiesis in the long term. Hence the data imply that the haemopoietic environment, as well as the dose-limiting lung, benefits from the use of low dose-rates for haemopoietic ablations in the treatment of leukaemia. No significant further sparing of CFU-F was achieved using a lower dose-rate of 1.4 cGy per minute.
D000818:Animals; D001853:Bone Marrow / Q000528:radiation effects*; D002588:Cesium Radioisotopes; D003114:Colony-Forming Units Assay; D005260:Female; D005720:Gamma Rays; D006412:Hematopoietic Stem Cells / Q000528:radiation effects*; D051379:Mice; D008815:Mice, Inbred Strains; D011829:Radiation Dosage; D013234:Stem Cells / Q000528:radiation effects*
D002588:Cesium Radioisotopes