Long-term survival of human myeloid progenitor cells induced by a mouse bone marrow stromal cell line

Mouse endothelial-adipocyte cell line (14F1.1), which induces proliferation of mouse stem cells in culture, is also capable of supporting long-term survival in culture of human myeloid progenitor cells; colony forming unit-granulocyte/macrophage (CFU-GM) was recovered from cultures incubated with the 14F1.1 cell line after over a month of incubation. The CFU-GM population increased beyond the input number, whereas, in control cultures initiated without stromal cells, the number of progenitors gradually declined. Addition of a relatively low concentration of human colony-stimulating factors (CSFs) into the cultures promoted the formation of "cobblestone areas," where mouse stroma and human hemopoietic cells closely interacted. 14F1.1 supernatant alone did not support the survival of human CFU-GM but synergized with the function of human granulocyte-macrophage colony-stimulating factor (GM-CSF) to stimulate adherent macrophage proliferation.