Bovine fetal-liver stromal cells support erythroid colony formation: enhancement by insulin-like growth factor II.
Stromal cells are one of the components of the hematopoietic microenvironment, which is crucial for the proliferation and differentiation of hematopoietic cells. We have obtained a bovine fetal-liver stromal cell line that supports erythroid colony formation in the presence of erythropoietin. The cells are cytokeratin-negative and vimentin-positive, indicating a mesenchymal origin. Furthermore, they have phagocytic activity and show endothelial-like morphology. Erythropoietin at a concentration of 2 mU/mL was sufficient to increase erythropoiesis in the presence of these stromal cells, and the effect could be further enhanced in the presence of physiological concentrations of insulin-like growth factor II. The supportive role of stromal cells on erythroid colony formation could still be observed, although to a lesser extent, when the erythroid precursors were physically separated from the stromal monolayer by an agar layer or with serum-free media conditioned by stromal cells. Ultrafiltration of the conditioned media indicated that the active factors have a nominal molecular weight smaller than 3 kD, which does not correspond to any of the known cytokines with erythroid-cell stimulating activities. Our data suggest that these fetal-liver stromal cells play an important role in fetal erythropoiesis, a function which was previously thought to be played exclusively by fetal hepatocytes.
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Endocrine Laboratory, Royal Victoria Hospital, Montreal, Quebec, Canada.
Congote
L F
LF
D000818:Animals; D002417:Cattle; D002450:Cell Communication; D004727:Endothelium / Q000166:cytology; D015672:Erythroid Precursor Cells / Q000166:cytology*; D004920:Erythropoiesis; D004921:Erythropoietin / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology*; D007633:Keratins / Q000032:analysis; D008099:Liver / Q000166:cytology / Q000196:embryology*; D008970:Molecular Weight; D010587:Phagocytosis; D017154:Stromal Cells / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D014746:Vimentin / Q000032:analysis
D014746:Vimentin; D004921:Erythropoietin; D007335:Insulin-Like Growth Factor II; D007633:Keratins