Age-related changes in the function of hemopoietic stroma in mice.

Hemopoietic function of the marrow and splenic stroma in C57BL/6 mice aging from 2 to 24 months were evaluated with the use of subcutaneous implantation method. Although there was no significant difference in the concentration as well as the total number of CFU(S) in femoral marrows between aged and young mice, the rates of CFU(S) repopulation in the femoral marrows from aged donors were significantly lower than in those from young donors when grafted subcutaneously in the 2 month-old syngeneic hosts. On the other hand, the femoral marrow grafts from 2 month-old donors were constantly repopulated irrespective of the age of the hosts. An essentially similar finding was obtained in the study of spleen grafts. It is suggested that the defective hemopoiesis, if any, in aged mice is primarily caused by the changes in hemopoietic stroma rather than those in hemopoietic stem cells.