Comparison of the hemopoietic growth factors produced during in vitro culture of murine and human fetal liver cells.

Under the conditions of in vitro liquid culture of murine fetal liver cells, some of the inoculated cells adhere to the flask surface. At optimum culture conditions, those adherent cells can survive and replicate for greater than 6 months in serial passages at intervals of 1 week. A similar adherent layer of cells on the flask surface occurred in a case with human fetal liver cells. These adherent cultured murine and human fetal liver cells can continuously release hemopoietic growth factors into the culture supernatant; among them spleen colony-forming unit (CFU-S) proliferation stimulator, erythrocyte-granulocyte-macrophage colony-stimulating factor (EGM-CSF), burst-promoting factor (BPF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been identified. These factors are not only active in triggering resting CFU-S into cell cycling, but also in the proliferation and differentiation of hemopoietic progenitors of different lines.