Stem Cell Kinetics in the L 5222 Rat Leukaemia

Abstract

The behaviour of normal haemopoietic stem cells of the bone marrow during the development of the acute transferable rat leukaemia, L 5222, has been investigated. The granulopoietic committed stem cells, measured by the in vitro colony technique, showed a marked decrease to less than half normal levels. Pluripotent stem cells included in the small lymphocytes of the bone marrow, and labelled with 3Hthymidine by the complete labelling method, showed only a modest decrease in number and an unchanged labelling intensity. The results suggest that in this leukaemia the pluripotent stem cells may be affected in such a way that they are unable to react by proliferation to the depletion of the succeeding cell compartments. This might be due to inhibition by leukaemic cells or to a disturbed feedback regulation between the committed and pluripotent stem cell compartments.

Interaction between Normal and Leukaemic Human Cells in Agar Culture

“…If normal haemopoietic stem cells are maintained during the disease, and these cells eventually are responsible for the apparently normal haemopoiesis in the remission state, why are these cells then restrained from proliferation and differentiation in the patient with untreated acute leukaemia? In animal experiments leukaemic cells have been shown to release inhibitory factors affecting normal granulopoiesis, and indications have been found of a disturbed feedback regulation between the committed and the pluripotent stem cell compartments (Handler et al 1974, Hoelzer et al 1974.…”