In vitro expansion of murine hematopoietic progenitor cells in liquid cultures for bone marrow transplantation: effects of stem cell factor.

In this study, we demonstrated that recombinant stem cell factor (SCF), when used in combination with interleukin-1 (IL-1), IL-3 and IL-1 plus IL-3, promoted the expansion of immature murine hematopoietic progenitor cells in liquid cultures. In cultures with IL-1 plus IL-3 plus SCF, high proliferative potential-colony forming cells (HPP-CFC) increased 7-8-fold compared with the increase in fresh bone marrow cells, while SCF alone had no effect on the expansion of HPP-CFC. SCF also increased the numbers of colony forming unit-spleen (CFU-S) cells in combination with IL-1 plus IL-3. Transplantation of bone marrow cells cultured with IL-1 plus IL-3 plus SCF resulted in reconstitution of hematopoiesis in lethally irradiated mice earlier than transplantation of fresh bone marrow cells. These results raised the possibility that in vitro expansion of hematopoietic progenitor cells, carried out with SCF in combination with IL-1 and IL-3 in liquid cultures, can be utilized in bone marrow transplantation.