THE PROLIFERATION AND DIFFERENTIATION CAPACITY OF HEMOPOIETIC STEM CELLS AFTER LARGE DOSE ~(60)Co IRRADIATION
Shen Ming-yan and Chu Jen-pao (Institute of Radiation Medicine,Academy of Military Medical Sciences,Beijing)
Large dose of ionizing radiation will cause a drastic reduction in number of hemopoietic stem cells (HSC) and bring about great chang-es in their functions,including proliferation and differentiation capacity. The results of experiments suggest that exposure of mice to 8.5 Gy γ-ray irradiation,the number and properties of hemopoietic stem cells together with progenitors,as well as the mature and functional cells would suffer a great change; the speed of recovery varied with the nature of different cells.The number of nucleated cells of bone marrow (BMC),white blood cells (WBC) and haemoglobin (Hb) may recover to normal within one month.The number of CFUs and GM-CFUc would take a period of 2-4 months for com-plete recovery.ConA-stimulated lymphocyte transformation remained abnormal even 3 months after irradiation.During a long period after irradiation,the residual HSC were still at a high degree of proliferation. All these facts indicate that HSC of 8.5 Gy v-ray irradiated mice still retain the poten-tial of proliferation and differentiation,al-though they have suffered a serious of lethal damage.