Identification of a growth factor for primary murine stroma as macrophage colony-stimulating factor.
Knowledge of the stromal microenvironment is crucial for understanding the hematopoietic system. We took advantage of an assay that permits analysis of primary stroma-initiating cells (SICs) on the clonal level, and further characterized SICs and the factors that regulate SICs. Stroma formation in this assay is dependent on a high-molecular-weight factor secreted by the stromal cell line AC3.U. Here we show that this factor is identical to macrophage colony-stimulating factor (M-CSF), and that purified M-CSF is sufficient for induction of stroma formation. M-CSF, isolated from the line AC3.U, as well as from L929 cells and COS cells transfected with an expression vector encoding M-CSF, migrated in two peaks as 160- and 650-kD species after gel filtration. These molecular-weight species encompassed all stroma-inducing activity, and both stimulated macrophage colony formation. Affinity chromatography and blocking studies with antibodies specific for M-CSF and c-fms confirmed M-CSF as the sole factor in the supernatant of the stromal cell line AC3.U that promotes stroma formation. Culture of marrow, for as little as 1 week, depleted M-CSF-dependent SIC while increasing the incidence of replatable, factor-independent SIC. This suggests that culture changes the properties of SICs, perhaps by inducing differentiation into mature stromal cells. Thus, our results show a novel function of M-CSF as an important modulator of stroma formation.
Deryugina
E I
EI
La Jolla Institute for Experimental Medicine (LJIEM), CA 92037, USA.
Ratnikov
B I
BI
Bourdon
M A
MA
Gilmore
G L
GL
Shadduck
R K
RK
Müller-Sieburg
C E
CE
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D015153:Blotting, Western; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D002469:Cell Separation; D002478:Cells, Cultured; D005434:Flow Cytometry; D016173:Macrophage Colony-Stimulating Factor / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology; D051379:Mice; D008807:Mice, Inbred BALB C; D008970:Molecular Weight; D017154:Stromal Cells / Q000166:cytology*
D000906:Antibodies; D016173:Macrophage Colony-Stimulating Factor