Human long-term bone marrow cultures in aplastic anemia.

Long-term bone marrow cultures (LTMC) were initiated with marrow from five normal subjects and eight patients with aplastic anemia (AA). Near confluent to confluent adherent layers developed in all cultures from normal subjects and AA patients. When present, the 'cobblestone' areas in LTMC from AA subjects were smaller than those observed in the LTMC from normal subjects. The decline in total and viable cell numbers in the LTMC was similar for both normal subjects and AA patients. Granulocyte-macrophage colony-forming units (CFU-gm) were present in nonadherent cells (NAC) from normal LTMC for a mean of 5.2 weeks. CFU-gm were present in the NAC of only two of the eight AA cultures for one week. The absent or small 'cobblestone' areas and the absence of CFU-gm production in AA-LTMC suggest a decrease in the reproductive potential of adherent hematopoietic stem cells, which may be the result of either an abnormal hematopoietic stem cell or an abnormal stromal microenvironment or both.