In vitro revelations of aplastic anemia.

Aplastic anemia (AA) is a most difficult disease to study in vitro. By the time the disease presents, the marrow is already hypocellular and the peripheral blood shows pancytopenia, leaving little material remaining for study. However, an understanding of its pathogenesis could provide insight into the control of normal hemopoiesis since AA is an in vivo manifestation of failure of normal hemopoiesis and may provide a way of examining stromal cell-stem cell relationships. Recent interest in the pathogenesis of AA has resulted from a) new laboratory techniques, such as stem cell purification used with modifications of the long-term bone marrow culture system and analysis of stem cells at the molecular level with X-linked DNA probes, and b) the availability of recombinant human hemopoietic growth factors (HGF) in large quantities. Consequently, analyses of the function of some of the individual components of stromal cell mediated hemopoiesis in AA patients have been performed. This has been paralleled, and in some instances preceded, by clinical trials of HGF in patients with AA.