In vivo chromosomal instability and transmissible aberrations in the progeny of haemopoietic stem cells induced by high- and low-LET radiations

Purpose: To study stable and unstable chromosomal aberrations in the haemop oietic cells of CBA/H mice after exposure to both high- and low-LET radiati ons. Materials and methods: Chromosomal aberrations were scored in the clonal pr ogeny of X-, alpha- or non-irradiated short-term repopulating stem cells us ing the spleen colony-forming unit (CFU-S) assay, 12 days post-transplantat ion and in the bone marrow reconstituted by X-, neutron- or non-irradiated exogenous (transplanted) or endogenous (X- or neutron whole-body-irradiated ) long-term repopulating stem cells for up to 24 months. Results: Chromosomal instability was demonstrated in 3-6% of cells in all c ases. After transplantation of X- or neutron-irradiated bone marrow similar to8% of cells with stable aberrations were recorded at all times. After 3 Gy X- or 0.5 Gy neutron- whole-body irradiation stable aberrations were det ected in similar to 17 and 5% of cells respectively. Conclusions: Chromosomal instability induced in vitro can be transmitted in vivo by transplantation of haemopoietic stem cells exposed to high- or low -LET radiations. Comparable instability can be induced and shown to persist for the remaining lifetime after whole-body irradiation. There was no dire ct relationship between the expression of stable and unstable aberrations a nd significant interanimal variation in the expression of both stable and u nstable aberrations.