Cytokinetics of Bone Marrow Stroma Cells after Stimulation by Partial Depletion of the Medullary Cavity

Abstract

The continuous administration of tridated thymidine (³H-TdR) into pregnant rats resulted in a complete labelling of cell nuclei in the offspring. Further injections with ³H-TdR for 6 weeks maintained the 100-percent labelling. Six weeks after the last ³H-TdR application, only cytokinetically resting cells were selectively labelled in the bone marrow of these animals. These comprised reticular cells, endothelial cells and 5% of the bone marrow lymphocyte population. In these animals a standardised amount of the marrow of both the femora was removed by mechanical means. In the undepleted part of the femur a stimulation of formerly cytokinetically resting cells could be observed. There was no indication of stimulation in distant bone marrow parts. In an additional experiment in which a single injection of ³H-TdR was given at various intervals after depletion, the above findings were supported by a high uptake of ³H-TdR in the stroma cells of the bone marrow. The findings indicate that repopulation of bone marrow stroma cells is a necessary process for a restoration of haemopoiesis.

The Role of Blood Stem Cells in Hematopoietic Cell Renewal

“…In summary, the observations are in agreement with the assumption that blood stem cell migration plays a crucial role in re-establishing a sufficient level of stem cells in bone marrow units that were rendered aplastic by irradiation or other means, for instance, mechanical depletion as shown by Meyer-Hamme et al [43].…”

Allosuppressor and allohelper T cells in acute and chronic graft-vs-host disease. I. Alloreactive suppressor cells rather than killer T cells appear to be the decisive effector cells in lethal graft-vs.-host disease.

“…In view of the tremendous regenerative capacity of the iympho-hemopoietic tissue, it has been argued that a general suppression of cell proliferation by TS cells would be much more efficient than cytotoxicity to cause cellular depletion in that tissue (13). A general suppression of cell proliferation should cause a depletion of most of the lympho-hemopoietic bone marrow cells because they are short-lived, but not of the neighboring reticular fibroblasts that are long-lived (40). This is precisely what we observed in the 2 ° F1 recipients of day-5 cells ( Fig.…”