Human tissues as source of colony-stimulating factor in human bone marrow cultures

Human bone marrow cells were cultured by the agar method using feeder layers containing human tissue fragments of various origin. Colony stimulating factor (CSF) was shown to be released from all tissues tested (adipose tissue, skeletal muscle, peritoneum and vascular wall), and primary cultures of human fibroblasts could also stimulate colony growth. Colony growth of murine bone marrow cells was also stimulated by all feeder layers. Thus, the study demonstrates that monocytes and macrophages might not be the only source of CSF of possible importance for human granulopoiesis in vivo.