The capacity of connective tissue stromas to sustain myelopoiesis depends both upon the growth factors and the local intercellular environment

Abstract

In adults, haemopoiesis is located in the bone marrow, where it is tightly regulated by cytokines and by a physical association of haemopoietic progenitors with the stroma. However, in pathological situations, haemopoiesis can be partly or fully dislodged to peripheral tissues. It is not clear which are the requirements for a given peripheral stroma to sustain haemopoiesis. Using the growth factor-dependent cell line FDC-P1, we have compared the myelopoietic capacities of a murine bone marrow-derived cell line S17, a liver inflammatory granuloma-derived stroma (GR) that sustains haemopoiesis, and normal skin fibroblasts (SF) that sustain neither survival nor proliferation of myeloid cells. All three stromas expressed mRNA for major haemopoietins with the exception of IL-3. Despite the incapacity of SF to sustain FDC-P1 cells, the biologically active GM-CSF could be recovered from all the studied stromas by treatment with high-salt buffers that release non-covalently bound molecules from stroma cells. Glycosaminoglycans purified from stromas had distinct effect on the GM-CSF-mediated proliferation of FDC-P1 cells: those purified from S17 and GR cells were stimulatory, whereas those obtained from SF cells were slightly stimulatory at low concentration, but inhibitory at the higher ones. We conclude that the quality of the stroma pericellular glycoconjugates is determinant for the ability of a given stroma to sustain myelopoiesis, even when biologically active haemopoietins are locally produced.

In Situ Replication of Immediate Dendritic Cell (DC) Precursors Contributes to Conventional DC Homeostasis in Lymphoid Tissue

“…Fibronectin has been reported to induce proliferation of mature DC (10). Although fibronectin had no effect in our system, it is possible that other matrix proteins such as heparin sulfate proteoglycans, which are produced by S17 cells and can modulate GM-CSF activity, are involved (39,40).…”

Dipeptidyl peptidase IV (CD26) activity in the hematopoietic system: differences between the membrane-anchored and the released enzyme activity

“…Our previous studies, as well as studies from other laboratories, have shown that the ability of a stroma to sustain myelopoiesis depends upon the stroma-associated glycoconjugates, and glycosaminoglycans in particular (23,(27)(28)(29). In order to determine whether the differences in the K M values for membrane-bound versus spontaneously released DPP-IV were a consequence of the loss of interactions of the enzyme with the cell membrane-associated molecules such as proteoglycans, we first assayed the effect of sulfated glycosaminoglycans on the stroma-derived enzyme K M .…”

“…The former two cell types sustain myelopoiesis whilst the last one does not. These cells were isolated, maintained, and characterized as previously described (21)(22)(23). Cells were maintained routinely in Dulbeccos minimum essential medium (DMEM; Sigma, St. Louis, MO, USA) supplemented with 10% fetal bovine serum (FBS; Cultilab, Campinas, SP, Brazil).…”

Heparin-binding Sites in Granulocyte-Macrophage Colony-stimulating Factor

“…Considerable evidence implicates the sulfated GAGs heparan sulfate and heparin in the modulation of the biological activity of GM-CSF (9,10,33,34). However, to date no GAGbinding sites in GM-CSF have been structurally identified.…”