Effect of irradiation on thermal sensitivity of bone marrow progenitors.
The heat sensitivity of murine CFU-GM and CFU-E following 2.5 Gy of total body irradiation (TBI) was studied. C3H f/Sed female mice were treated with 2.5 Gy TBI and femoral bone marrow was heated in vitro at 43 degrees C. CFU-GM show heat radiosensitization when bone marrow was heated immediately following irradiation. There was a brief decline in heat and radiation interaction when cells were heated 3 hours following 2.5 Gy of TBI, but heat radiosensitization returned to its maximum from 1 to 2 days following irradiation and remained significantly different from the control on days 5 and 7 following irradiation. The heat and radiation interaction disappeared by 30 days. CFU-E shows significant heat radiosensitization only on day 2 following 2.5 Gy of TBI. Total nucleated cells per femur showed a decrease by 70 per cent in days 1 to 2 following TBI, recovered to control values by day 5, and did not correlate with the changes in heat radiosensitization. Cell cycle analysis of CFU-GM using hydroxyurea showed no significant changes in cell cycle parameters on days 1 and 2 following 2.5 Gy, when maximum heat sensitization was observed. It is concluded that bone marrow progenitors may respond in a different way from other normal tissues to heat and irradiation sequencing, and that these differences must be considered when designing clinical trials.
Mivechi
N F
NF
Radiation Oncology Research Laboratory, University of California, San Francisco 94143.
Li
G C
GC
D000818:Animals; D001853:Bone Marrow / Q000528:radiation effects; D001854:Bone Marrow Cells; D016026:Bone Marrow Transplantation; D002453:Cell Cycle / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D003131:Combined Modality Therapy; D005260:Female; D006098:Granulocytes / Q000032:analysis / Q000528:radiation effects; D006412:Hematopoietic Stem Cells / Q000528:radiation effects; D006358:Hot Temperature; D006979:Hyperthermia, Induced / Q000009:adverse effects*; D066298:In Vitro Techniques; D008264:Macrophages / Q000032:analysis / Q000528:radiation effects; D051379:Mice; D011836:Radiation Tolerance; D013234:Stem Cells / Q000528:radiation effects*; D013997:Time Factors; D014916:Whole-Body Irradiation