
Radiation contamination can occur from natural radiation or from man-made sources, such as radiation for medical research or for nuclear weapons manufacture, and this one of the major problems facing the ratio biologists is how to infer the biological bad effects resulting from γ- radiation exposure. The aim of the work is to investigate the effects of γ-radiation exposure on the blood picture, liver function, kidney function and TNF-α of albino rats, and using mesenchymal stem cells (MSCs) to treatment these effects. The animals were divided into 5 groups: Control, γ-irradiation (6 grays), stem cells, γ-irradiation treated with stem cells post-irradiation and the 5th groups for preparation of mesenchymal stem cells for engrafting after one week and two weeks post-irradiation. The present study was undertaken to examine the effects of two dosages of MSCs on the survival of rats exposed to lethal doses of total body irradiation (TBI), and to explore the mechanisms by which MSCs in significantly improve gamma radiation effects.