Acute radiation syndrome caused by accidental radiation exposure - therapeutic principles

Fortunately radiation accidents are infrequent occurrences, but since they have the potential of large scale events like the nuclear accidents of Chernobyl and Fukushima, preparatory planning of the medical management of radiation accident victims is very important. Radiation accidents can result in different types of radiation exposure for which the diagnostic and therapeutic measures, as well as the outcomes, differ. The clinical course of acute radiation syndrome depends on the absorbed radiation dose and its distribution. Multi-organ-involvement and multi-organ-failure need be taken into account. The most vulnerable organ system to radiation exposure is the hematopoietic system. In addition to hematopoietic syndrome, radiation induced damage to the skin plays an important role in diagnostics and the treatment of radiation accident victims. The most important therapeutic principles with special reference to hematopoietic syndrome and cutaneous radiation syndrome are reviewed

Sensitivity and dose dependency of radiation-induced injury in hematopoietic stem/progenitor cells in mice

We evaluated the sensitivity and dose dependency of radiation-induced injury in hematopoietic stem/progenitor cells. Adult C57BL/6 mice were daily exposed to 0, 2, 10, 50, and 250 mGy γ-ray for 1 month in succession, respectively. The damage of hematopoietic stem/progenitor cells in bone marrow were investigated within 2 hours (acute phase) or at 3 months (chronic phase) after the last exposure. Daily exposure to over 10 mGy γ-ray significantly decreased the number and colony-forming capacity of hematopoietic stem/progenitor cells at acute phase, and did not completely recover at chronic phase with 250 mGy exposure. Interestingly, the daily exposure to 10 or 50 mGy γ-ray decreased the formation of mixed types of colonies at chronic phase, but the total number of colonies was comparable to control. Immunostaining analysis showed that the formation of 53BP1 foci in c-kit + stem/progenitor cells was significantly increased with daily exposure to 50 and 250 mGy at acute phase, and 250 mGy at chronic phase. Many genes involved in toxicity responses were up- or down-regulated with the exposures to all doses. Our data have clearly shown the sensitivity and dose dependency of radiation-induced injury in hematopoietic stem/progenitor cells of mice with daily exposures to 2 ? 250 mGy γ-ray

Early and Late Protective Effect of Bone Marrow Mononuclear Cell Transplantation on Radiation-Induced Vascular Dysfunction and Skin Lesions

International audienceSkin lesions caused by accidental exposure to radiation or by radiotherapy are a major clinical challenge. We evaluated the effect of bone marrow mononuclear cells (BMMNC) on collagen remodeling and vascular function in radiation-induced skin lesions in the acute and late phases in mice. We studied the effect of BMMNC transplantation in a mouse model of cutaneous radiation injury combining local skin gamma-irradiation and biopsy punch wound. Mice were first irradiated, punched and then BMMNC were intramuscularly administered. Seven days after injury, BMMNC promoted wound healing by (i) increasing re-epithelialization, tissue collagen density and mRNA levels of collagens 1A1, 1A2, and 3A1, and (ii) inhibiting the radiation-induced vascular activation and limiting interactions between leukocytes and the vascular endothelium compared with control. Importantly, BMMNC did not amplify the inflammatory response despite the infiltration of neutrophils and macrophages associated with the expression of IL-6 and MCP-1 mRNAs in the tissue. Remarkably, the beneficial effects of BMMNC therapy on matrix remodeling were maintained for 2 months. Furthermore, BMMNC injection restored vascular function in skin tissue by increasing vascular density and vascular permeability. This therapeutic strategy based on BMMNC injection protects against radiation-induced skin lesions by preventing vascular dysfunction and unfavorable remodeling in the acute and late phases

Initial evaluation and follow-up of acute radiation syndrome in two patients from the Dakar accident

The aim of this work was to evaluate and follow up the evolution of radiation damage in two victims of a radiation accident. Blood samples were used for cytogenetic evaluation of radiation dose and heterogeneity. The radiation dose estimates were 1 Gy and 2.3 Gy in the two most exposed patients. Plasma was used for the measurement of the Flt3 ligand as a marker of haematopoietic aplasia, citrulline for damage to the jejunal mucosal epithelium and oxysterols for damage to the liver, the central nervous system and the vascular compartment. The use of these biological indicators demonstrated the presence of a haematopoietic syndrome and suggested the presence of subclinical radiation-induced damage to the liver in one of the two patients. These results support the interest in using these biological indicators in order to evaluate radiation damage, especially in complex accidental situations. © 2009 Informa UK Ltd

New biological indicators to evaluate and monitor radiation-induced damage: An accident case report

The aim of this work was to use several new biological indicators to evaluate damage to the main physiological systems in a victim exposed accidentally to ionizing radiation. Blood samples were used for biological dosimetry and for measurement of the plasma concentrations of several molecules: Flt3 ligand to assess the hematopoietic system, citrulline as an indicator of the digestive tract, and several oxysterols as lipid metabolism and vascular markers. The cytogenetic evaluation estimated the dose to the victim to be between 4.2 and 4.8 Gy, depending on the methodology used. Monitoring the Flt3 ligand demonstrated the severity of bone marrow aplasia. In contrast, the citrulline concentration showed the absence of gastrointestinal damage. Variations in oxysterol concentrations suggested radiation-induced damage to the liver and the cardiovascular system. These results were correlated with those from classic biochemical markers, which demonstrated severe damage to the hematopoietic system and suggested the appearance of subclinical damage to the liver and cardiovascular system. These results demonstrate for the first time the importance of a multiparameter biological approach in the evaluation of radiation damage after accidental irradiation. © 2008 by Radiation Research Society

Protective effect of geranylgeranylacetone against radiation-induced delayed effects on human keratinocytes

International audienceSkin exposure to ionizing radiation affects the normal wound healing process. We investigated the beneficial effects of a pharmacological treatment with geranylgeranylacetone (GGA) on keratinocytes using in vitro scratch wound injury assay in nonirradiated and irradiated conditions. Irradiation affected the wound closure of keratinocytes 24 h after scratch injury, whereas re-epithelialization was markedly accelerated after GGA treatment when compared to nontreated keratinocytes. We demonstrated that GGA treatment increased migration of human epidermal keratinocytes and this migratory property was not related to RhoA signaling. Interestingly, Western blot analysis revealed that GGA treatment down-regulated caspase 3 active form expression and up-regulated the activated phenotype by inducing both keratin 6 (K6) expression and interleukin-1β (IL-1β) release without modification of the differentiate phenotype. Finally, the proteomic profiling was performed on keratinocytes, showing that global protein changes occurred after irradiation of keratinocytes treated or untreated with GGA