Studies on the role of serum in long-term bone marrow cell cultures.

The effect of fetal calf serum (FCS) concentration on hemopoiesis in long-term bone marrow cell cultures (supplemented with 10(-6) M hydrocortisone) was investigated. The duration of hemopoiesis was directly related to the concentration of serum in the cultures. At each concentration, marked differences were seen between different batches of FCS. The longevity of cultures established with a suboptimum concentration of serum was increased by the addition of HEPES buffer. Removal of all non-adherent cells and growth medium for the weekly feedings increased the overall production of hemopoietic cells when compared to the standard feeding procedure of replacing one-half of the growth medium.