SPECIES-DIFFERENCES IN GROWTH REQUIREMENTS FOR BONE-MARROW STROMAL FIBROBLAST COLONY FORMATION IN-VITRO

The marrow stromal fibroblast (MSF) population has been shown to inclu de precursor cells for at least five types of connective tissue: bone, cartilage, adipose tissue, fibrous tissue, and hematopoiesis-supporti ng reticular stroma. In this study, growth requirements for MSF colony formation were studied in vitro. In order to exclude the influence of nonadherent cells, after a period of initial adhesion of bone marrow cells in serum-containing medium nonadherent cells were removed. Furth er cultivation was carried out in either serum-containing or serum-fre e conditions, with or without feeder cells (irradiated bone marrow cel ls). This approach revealed differences between animal species in init ial MSF growth requirements. In serum-containing conditions, mouse MSF precursor cells (colony-forming units-fibroblast, CFU-Fs) were shown to be feeder cell dependent: MSF colonies were formed only in the pres ence of feeder cells. Guinea pig CFU-Fs were partially feeder cell de pendent, whereas human CFU-Fs were feeder cell independent. In serum-f ree conditions, CFU-Fs of all three species were feeder cell dependent . The difference between the growth requirements for mouse and human M SFs was not caused by serum origin or concentration, feeder cell origi n, or differences in the preparation of marrow cell suspensions.