COMPARISON OF THE PROLIFERATIVE RESPONSES OF HEMATOPOIETIC STEM CELLS EXPOSED TO LOW DOSE RATE RADIATION IN VIVO AND EX VIVO

Radiat Prot Dosimetry. 2022 Sep 9;198(13-15):1025-1029. doi: 10.1093/rpd/ncac042.

Abstract

The hematopoietic stem cells (HSCs) are sensitive to radiation. Chronic exposure to low dose rate (LDR) radiation at 20 mGy/day results in a decrease in the number of HSCs and an increase of leukemia. In this study, the proliferative capacities of ex vivo HSCs, exposed to 20 mGy/day of gamma-rays for 20 days, were compared with those of in vivo HSCs from similarly whole-body-irradiated mice. Radiation suppressed the growth of the ex vivo HSCs after Day 16 of irradiation and until Day 7 post-exposure. Almost all types of cells, particularly multipotent progenitors, common myeloid progenitors, granulocytes and macrophages, were significantly reduced in number at Day 20 of irradiation and Day 7 post-exposure in culture. HSCs and multipotent progenitors irradiated in vivo, however, decreased transiently and recovered by Day 7 post-exposure. These findings suggest that the microenvironment in vivo protects HSCs from the effects of LDR radiation.

MeSH terms

  • Animals
  • Gamma Rays
  • Hematopoietic Stem Cells* / radiation effects
  • Mice