Modeling the Optimum Prussian Blue Treatment for Acute Radiation Syndrome Following 137Cs Ingestion

Radioprotection and Radiomitigation: From the Bench to Clinical Practice

The development of protective agents against harmful radiations has been a subject of investigation for decades. However, effective (ideal) radioprotectors and radiomitigators remain an unsolved problem. Because ionizing radiation-induced cellular damage is primarily attributed to free radicals, radical scavengers are promising as potential radioprotectors. Early development of such agents focused on thiol synthetic compounds, e.g., amifostine (2-(3-aminopropylamino) ethylsulfanylphosphonic acid), approved as a radioprotector by the Food and Drug Administration (FDA, USA) but for limited clinical indications and not for nonclinical uses. To date, no new chemical entity has been approved by the FDA as a radiation countermeasure for acute radiation syndrome (ARS). All FDA-approved radiation countermeasures (filgrastim, a recombinant DNA form of the naturally occurring granulocyte colony-stimulating factor, G-CSF; pegfilgrastim, a PEGylated form of the recombinant human G-CSF; sargramostim, a recombinant granulocyte macrophage colony-stimulating factor, GM-CSF) are classified as radiomitigators. No radioprotector that can be administered prior to exposure has been approved for ARS. This differentiates radioprotectors (reduce direct damage caused by radiation) and radiomitigators (minimize toxicity even after radiation has been delivered). Molecules under development with the aim of reaching clinical practice and other nonclinical applications are discussed. Assays to evaluate the biological effects of ionizing radiations are also analyzed.

Emergency response to radiological and nuclear accidents and incidents

Bone marrow damage is an important consequence of exposure to acute high-dose whole-body radiation. As such, haematologists can play an important role in managing this complication. However, these accident and incident scenarios are complex and often involve injuries to other organs and tissues from heat, projectiles and chemicals. In the case of a large-scale event there will likely be severe infrastructure disruptions and injury or death to medical personnel. Accurate estimates of dose and uniformity of exposure are needed to intelligently direct appropriate interventions, which range from antibiotics, antifungals and anti-virus drugs, molecularly-cloned haematopoietic growth factors and, in rare instances, haematopoietic cell transplants. These therapies are ones that haematologists often use in the context of anti-cancer therapy, especially therapy of haematological cancers like leukaemia. However, most haematologists have little knowledge of radiation biology and should consider updating this aspect of their expertise in continuing medical education. As in other areas of medicine, prevention is better than cure and haematologists should be active in decreasing risks of a nuclear war.