Hemopoietic support capacity of adult mouse liver. Studies in 89Sr marrow-ablated mice

The capacity of normal livers in adult mice to support proliferation of pluripotent hemopoietic stem cells (CFU-S) was studied. We assayed CFU-S of the blood and livers of mice with intact marrows and of mice whose marrows had been ablated with 89Sr (4 μCi/g) either before or after removal of their spleens, the major hemopoietic organ in marrow-ablated mice. Splenectomy alone resulted in an increase in the numbers of blood and hepatic CFU-S; since the spleen is an efficient trapper of CFU-S released from the marrow, in the splenectomized mice more CFU-S were available for trapping by the liver. Mice splenectomized 3 days prior to 89Sr injection had virtually no blood or liver CFU-S by the tenth day after 89Sr injection. Fourteen days after injection of 89Sr there were supranormal numbers of CFU-S in both blood and liver of intact mice. One week after such mice were splenectomized, however, CFU-S were virtually absent from both blood and liver. This study suggests that normal livers in adult mice cannot support detectable proliferation of normal CFU-S even if the animal is subjected to severe and relatively prolonged hemopoietic stress. In addition, the results of our studies demonstrate that normal livers of adult mice have the capacity to trap large numbers of CFU-S