Abstract: Mesenchymal stem cells(MSCs) are a source of various multipotent stromal cells with low inherent immunogenicity.These cells can undergo multi-directional differentiation, support hematopoiesis, and regulate immune responses.MSCs can be easily collected and amplified.These cells can also be transfected using an exogenous gene.MSCs have been extensively applied in clinical treatments, such as in the therapy for acute radiation injury.This study was primarily performed to investigate the effect and mechanism of MSCs in acute radiation injury.