Synergistic effects of stem cell factor and interleukin 6 or interleukin 11 on the expansion of murine hematopoietic progenitors in liquid suspension culture.

Abstract

The synergistic effects of stem cell factor (SCF) in combination with other growth factors including interleukin (IL)-6, IL-11, IL-3, GM-CSF, G-CSF, IL-1 alpha and interferon-gamma (IFN-gamma) on the expansion of murine hematopoietic progenitors were studied in a short-term liquid suspension culture system. Bone marrow (BM) cells obtained 2 days after 5-fluorouracil (5-FU) injection were cultured for up to 18 days in serum-containing and serum-free cultures in the presence of combinations of various cytokines. The numbers of nucleated cells, total colony-forming cells (CFC), mixed-colony forming units (CFU-Mix) and high-proliferative potential colony-forming cells (HPP-CFC) before and after liquid suspension cultures were measured in the presence of different combinations of cytokines. Combinations of SCF with IL-11, IL-6 or IL-1 alpha markedly increased the numbers of total CFC, CFU-Mix and HPP-CFC. A combination of SCF and IL-3 also expanded the number of total CFC; however, the fold increase was smaller than those of SCF plus IL-11, IL-6 or IL-1 alpha. Three or four factor combinations including SCF with IL-3, IL-6 and IL-11 did not yield increased numbers of total CFC over that supported by SCF plus either IL-6 or IL-11. The addition of IFN-gamma to the culture containing SCF plus IL-11 resulted in a decrease of the expansion efficiency. However, this difference is not statistically significant. In contrast, the addition of IFN-gamma to the cultures containing SCF plus IL-6 did not affect the expansion efficiency. Interestingly, the addition of IL-1 alpha in the culture containing SCF plus IL-3 significantly increased the number of HPP-CFC over that supported by SCF plus IL-3 (p < 0.01). In contrast, IL-1 alpha did not significantly affect the expansion efficiency in the presence of SCF plus IL-6 or IL-11. These results suggest that combinations of SCF plus either IL-6 or IL-11 or a combination of SCF, IL-3 and IL-1 alpha can most effectively expand murine hematopoietic progenitors derived from day-2 post-5-FU BM cells in vitro.