MSC-Derived Extracellular Vesicles: New Emergency Treatment to Limit the Development of Radiation-Induced Hematopoietic Syndrome?

Nuclear accidents or acts of terrorism involving radioactive sources might lead to mass casualties irradiation. The hematopoietic system is one of the most critical and radiation-sensitive tissues because the limited life span of blood cells requires the continuous division of hematopoietic stem cells (HSCs) into the bone marrow. The radiation-induced hematopoietic syndrome, RI-HS, is an impairment of the hematopoiesis that will result in pancytopenia of various degrees. In fact, treatment with granulocyte-colony stimulating factor (G-CSF) is considered as a valuable adjunct to treatment controls in some irradiated patients. Nevertheless, these overexposed patients with bone marrow suppression have minimal medullary territories that do not allow complete recovery of hematopoiesis but lead to significant immunoreactivity following allogeneic hematopoietic stem cell transplantation (HSCT). The high morbidity and mortality of these overexposed patients is a reminder of the lack of effective treatment for hematopoietic syndrome. During the last 20 y, a therapeutic approach for mesenchymal stem cells (MSC) has been proposed for the management of accidentally irradiated victims. Many preclinical animal studies have shown that MSC, mainly by their secretory activity, in particular extracellular vesicles (EVs), contribute to the control of inflammation and promote regeneration of tissues by accelerating angiogenesis and re-epithelialization processes. Therefore, we investigated the potential effect of EVs on the reduction of early bone marrow ionization toxicity, early anti-apoptotic therapy, and vascular protection in the RI-HS model. The main purpose is to propose an innovative treatment of non-patient-specific RI-HS emergency treatment in order to limit allogeneic HSC.