Studies of haemopoietic stem cells and microenvironment in chronic irradiated mice

Mice were irradiated at a dose rate of 70 rad per day for 25 days. Changes in properties and functions of haemopoietic stem cells and microenvironment were observed through a period of 12 months after termination of continuous irradiation. It was shown that the radiation damage of haemopoietic stem cells played an important role in the radiation-induced damage of haemopoiesis. This was further supported by the fact that transplantation of syngeneic bone marrow cells immediately after termination of continuous irradiation at 70 rad per day for 25 days would greatly improve the haemopoietic function of the irradiated mice, including the total recovery of CFU-S and numbers in the bone marrow and cell counts in the peripheral blood.