AM5, a protein-associated polysaccharide, stimulates hematopoiesis and modulates the expression of endogenous hematopoietic growth factors in murine long-term bone marrow cultures.
We have investigated the mechanism behind the hematopoietic stimulation mediated by AM5, a protein-associated polysaccharide that stimulates in vivo the murine hematopoietic system. A dose-dependent increase in hematopoietic progenitors was observed in long-term bone marrow cultures (LTBMCs) treated in vitro with AM5. The stimulatory effect was more marked in colony-forming units-granulocyte-macrophage (CFU-GM) than in CFU-spleen (CFU-S) progenitors and also more significant in the supernatant than in the adherent layer. This stimulatory effect was reversible, and continuous stimulation with high doses of AM5 was conductive to a progressive exhaustion of the culture. The analysis of the CFU-GM stimulating activity present in the supernatant of AM5-treated cultures revealed a dose-dependent induction of granulocyte-macrophage colony-stimulating activity (GM-CSA), in contrast with control cultures in which no CSA was detected. Northern blots of LTBMC-adherent layers obtained after in vitro treatment with AM5 revealed a significant mRNA expression for interleukin 1 alpha (IL-1 alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), macrophage CSF (M-CSF) and granulocyte CSF (G-CSF), in contrast with adherent layers from untreated cultures which only expressed, in detectable levels, M-CSF and stem cell factor (SCF). The SCF expression was down-modulated in AM5-treated cultures. Our results strongly suggest that the hematopoietic stimulation induced by AM5 is mediated by the modulated expression of endogenous hematopoietic growth factors.
Güenechea
G
G
Unidad de Biología Molecular y Celular, CIEMAT, Madrid, Spain.
Bueren
J A
JA
Maganto
G
G
Tuduri
P
P
Guerrero
A
A
Pivel
J P
JP
Real
A
A
D000818:Animals; D001681:Biological Assay; D001853:Bone Marrow / Q000187:drug effects / Q000378:metabolism; D001854:Bone Marrow Cells; D002175:Candida; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D046508:Culture Techniques / Q000379:methods; D015342:DNA Probes; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects*; D016179:Granulocyte Colony-Stimulating Factor / Q000096:biosynthesis; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis; D006410:Hematopoiesis / Q000187:drug effects*; D016298:Hematopoietic Cell Growth Factors / Q000096:biosynthesis*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D007375:Interleukin-1 / Q000096:biosynthesis; D016173:Macrophage Colony-Stimulating Factor / Q000096:biosynthesis; D008297:Male; D008351:Mannans / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D019089:Stem Cell Factor
C075974:AM5; D015342:DNA Probes; D016298:Hematopoietic Cell Growth Factors; D007375:Interleukin-1; D008351:Mannans; D012333:RNA, Messenger; D019089:Stem Cell Factor; D016179:Granulocyte Colony-Stimulating Factor; D016173:Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor