[Isolation and characterization of the hematopoietic stem cell].

When one hundred of c-Kit+Sca-1+Lin- cells obtained from B6. Ly 5.1 mouse were injected into lethally irradiated B6. Ly 5.2, 100% of the mice injected survived. Sequential analyses of recipient's peripheral blood leukocytes revealed presence of Ly 5.1+ myeloid and lymphoid cells even 12 months after the injection. We also examined the fate of these cells in the recipient mouse after transplantation. Time course analyses of the mouse injected with 500 FACS-purified c-Kit+Sca-1+L- cells revealed that spleen is the primary site for expansion of the injected c-Kit+Sca-1+Lin- cells. By day 28 s/p transplantation, more than 50,000 donor type c-Kit+Sca-1+Lin- cells were found in the spleen and over 15,000 cells in the bone marrow. By day 60, number of c-Kit+Sca-1+Lin- cells decreased in the spleen and returned to normal level in the bone marrow. Stem cell activity of the donor derived c-Kit+Sca-1+Lin- cells in the primary recipient was confirmed by in vitro and in vivo colony formation as well as transplantation to the secondary recipient. These results provide evidence that c-Kit+Sca-1+Lin- cells in the bone marrow have capability of self-renew as well as multilineage differentiation potential and that spleen is the primary site of stem cell expansion after bone marrow transplantation in mouse.