Which place for stem cell therapy in the treatment of acute radiation syndrome?

Radiation-induced (RI) tissue injuries can be caused by radiation therapy, nuclear accidents or radiological terrorism. Notwithstanding the complexity of RI pathophysiology, there are some effective approaches to treatment of both acute and chronic radiation damages. Cytokine therapy is the main strategy capable of preventing or reducing the acute radiation syndrome (ARS), and hematopoietic growth factors (GF) are particularly effective in mitigating bone marrow (BM) aplasia and stimulating hematopoietic recovery. However, first, as a consequence of RI stem and progenitor cell death, use of cytokines should be restricted to a range of intermediate radiation doses (3 to 7 Gy total body irradiation). Second, ARS is a global illness that requires treatment of damages to other tissues (epithelial, endothelial, glial, etc.), which could be achieved using pleiotropic or tissue-specific cytokines. Stem cell therapy (SCT) is a promising approach developed in the laboratory that could expand the ability to treat severe radiation injuries. Allogeneic hematopoietic stem cell transplantation (BM, mobilized peripheral blood and cord blood) transplantation has been used in radiation casualties with variable success due to limiting toxicity related to the degree of graft histocompatibility and combined injuries. Ex vivo expansion should be used to augment cord blood graft size and/or promote very immature stem cells. Autologous SCT might also be applied to radiation casualties from residual hematopoietic stem and progenitor cells (HSPC). Stem cell plasticity of different tissues such as liver or skeletal muscle, may also be used as a source of hematopoietic stem cells. Finally, other types of stem cells such as mesenchymal, endothelial stem cells or other tissue committed stem cells (TCSC), could be used for treating damages to nonhematopoietic organs.