Quantitative development of adherent cell colonies in bone marrow cell culture in vitro.

Quantification of the formation of adherent cell colonies in bone marrow cell culture was attempted. By secondary transfer of the bone marrow cells as a single cell suspension after 4 days' culture of fine marrow fragments, a linear relationship was obtained between the number of adherent cell colonies developing and the number of cells secondarily inoculated into the culture bottle. This suggests that 4 days' culture of the bone marrow cells with close intercellular interactions is sufficient for the 'conditioning' of the cells to develop adherent cell colonies. Activity of such colonies to support haemopoietic stem cell proliferation was also shown.