The François Jacob Institute of Biology brings together five departments and three services
The last two years in scientific news
Highlight | News | Scientific result | Radiotherapy | Radiosensitivity
An IRCM team (CEA/Inserm) has shown that exposure to low-dose ionizing radiation causes functional losses in human hematopoietic stem cells. Their results, published in Haematologica, suggest the need for complementary care during radiation therapy regimens.
hematopoietic system has long been known for its particularly high
radiosensitivity, but how it reacts to the low-dose ionizing radiation
delivered during radiation therapy had remained unknown and thus in need of
A team from the Laboratory of Hematopoietic
Stem Cells and Leukemia (LSHL) tackled that issue and showed that
low-dose ionizing radiation (LDIR) exposure does indeed cause functional losses
in human hematopoietic stem cells (HSCs). These latter reside in the bone
marrow and give rise to all types of blood cells. HSCs renew themselves as
necessary to reconstitute their own population.
their study, the LSHL researchers isolated human HSCs from umbilical cord blood
and exposed them to both low (0.02 Gy) and high (2.5 Gy) cobalt-derived
radiation doses. Various in vitro (including colony forming unit (CFU)
assays) and in vivo (grafts in immunodeficient mice) evaluations were
used to determine the functional properties of those cells. More precisely,
their tests, performed in series, were aimed at determining both the
differentiation and self-renewal capacities of the human HSCs.
team's results showed that HSCs exposed to 0.02 Gy do suffer long-term losses
of functional properties, notably their ability to generate secondary CFUs in
vitro and their capacity for hematopoietic reconstitution in vivo.
No DNA alteration or cell death induction was observed. Rather, the team reported
that immediately after radiation exposure, the HSCs showed an increase in
reactive oxygen species (ROS) and activation of the p38MAPK signaling pathway,
which has a known role in maintaining the "stem" properties of those
cells. Thereafter, to ensure that the ROS-p38MAPK pathway was indeed
responsible for the observed effects, HSCs were treated with either
antioxidants or p38MAPK pathway inhibitors before exposure to LDIR. Indeed, the
inhibition of that pathway blocked the effect of LDIR on the long-term
functional properties of human HSCs.
results published by the LSHL team show that LDIR has long-term effects on the
ability of HSCs to regenerate themselves, due in part to an increase in ROS.
additional management via the deployment of antioxidants or p38MAPK inhibitors
may be necessary during radiation treatments or examinations to protect the
Human hematopoietic stem/progenitor cells display ROS-dependent long-term hematopoietic defects after exposure to low dose of ionizing radiations I Haematologica
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.