Postirradiation Hemopoietic Repopulation and Stromal Cell Viability

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Abstract
To evaluate some microenvironmental conditions necessary to support hemopoiesis, the right femurs of mice were X-irradiated. Femoral 59Fe uptake in the right femur after 1000 rad fell to 20 .+-. 2% of the control (mean .+-. 1 SEM [standard error of mean]) at 3 days and returned to 67 .+-. 5% by 6 mo. Erythroblast counts reflected these changes. Total nucleated cell counts initially diminished to 21 .+-. 3% of control but increased to 76 .+-. 6% of normal by 6 mo. Counts of bone marrow stromal cells in culture rose from 13 .+-. 4% of control at 3 days to 77 .+-. 11% by 6 mo. Except for temporary elevation in 59Fe uptake at 1 wk, animals receiving 5000 or 10,000 rad to the right femur had persistently low levels (< 30%) of total nucleated cell counts, stromal cell counts, 59Fe uptake and erythroblast counts over 6 mo. In the unirradiated marrow of these animals, the 59Fe uptake and erythroblast counts were less than normal, and total nucleated cell counts and splenic 59Fe uptake and weights were above normal through 6 mo. At 5000 or 10,000 rad sustained recovery of hemopoietic cells and stromal cells was inhibited, 1000 rad permitted slightly subnormal hemopoietic repopulation and stromal cell recovery, and the unirradiated marrow and spleen underwent dose- and time-dependent changes.