The Radiation Sensitivity of Normal Mouse Bone Marrow Cells, Determined by Quantitative Marrow Transplantation into Irradiated Mice

Abstract

An estimate of the radiation sensitivity of normal mouse bone marrow cells was obtained by utilizing the fact that the decrease in mortality of lethally irradiated mice following intravenous injection of bone marrow is a function of the number of cells injected. After 950 rads of total-body irradiation with X-rays, groups of 20 mice were injected with different dilutions of marrow suspension and the 30 day mortality was observed. Maximal survival (80 to 90%) was obtained with 106 cells, and decreased progressively as the number of cells administered was decreased, falling to zero when 104 cells were given. Irradiation of the marrow suspension reduced the survival obtained with 106 cells. The radiation sensitivity of normal Swiss or C57 Bl mouse marrow cells, expressed as the dose required to reduce the percentage of viable cells to 37% (D37), is 105 [plus or minus] 24 rads, the cells having a similar sensitivity when irradiated in vivo or in vitro.