Radiosensitivity and postirradiation changes of bone marrow clonogenic stromal mechanocytes.

The in vitro colony assay was used to determine radiosensitivity and post-irradiation changes of guinea pig clonogenic bone marrow stromal fibroblasts (CFU-F). D0 of the CFU-F survival curve proved to be about 200 rad, while n is 1.4. Immediately after total-body exposure to 400 rad and to local exposure of tibias to 400 rad, the number of CFU-F diminishes in accordance with D0; it sharply increases after 6 hours and then decreases again. In the period between the eighth and twelfth day following local irradiation, the number of CFU-F doubled in the course of 30-35 hours but later the rate of recovery slowed down. Practically no CFU-F were traced during 3 months after local exposure to 2 krad.