Extramedullary hematopoiesis in the adult mouse liver is associated with specific hepatic sinusoidal endothelial cells.
In previous work, two anatomically distinct-liver sinusoid endothelial cells (LEC): LEC-1 and LEC-2, have been described. We also reported that extramedullary hepatic hematopoiesis occurs only in close contact with LEC-1, suggesting that these cells may provide the microenvironment necessary for the maintenance and growth of hematopoietic cells. In the present work, we studied the capacity of LEC-1 and LEC-2 to maintain in vitro hematopoiesis. LEC-1 and LEC-2 were isolated and cloned from livers of adult mice. Bone marrow cells (BM) enriched with primitive hematopoietic progenitors were isolated from day-2, post-5-FU-treated mice (5-FUBMC). LEC-1 supported the maintenance and differentiation of hematopoietic progenitors for more than 6 weeks in vitro. In contrast, LEC-2 cells poorly supported the proliferation of hematopoietic cells for only two weeks of the co-culture. LEC-1 and 5-FUBMC cocultures showed cobblestone-area formation and the presence of hematopoietic progenitors that are able to form colonies (CFC) in the adhering fraction after six weeks of coculture. LEC-1 co-cultures treated with a cocktail of cytokines (stem cell factor, interleukin [IL]1alpha, IL-3, and Epo) showed that megakaryocyte (CFU-Mk) and erythrocyte progenitors (BFU-e) were present during the entire period of the culture. Granulocyte-macrophage progenitors (CFU-GM) were present only during the first three weeks of the culture. These results suggest that LEC-1, but not LEC-2, provide an appropriate hematopoietic microenvironment for supporting the proliferation and differentiation of primitive hematopoietic cells. This could explain the anatomical restriction of hematopoietic cells for growing in LEC-1 domains during liver extramedullary hematopoiesis.
Cardier
J E
JE
Arthur G. James Cancer Hospital and Research Institute at The Ohio State University, Columbus 43210, USA.
Barberá-Guillem
E
E
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000737:chemistry / Q000502:physiology*; D006411:Hematopoiesis, Extramedullary / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D006651:Histocytochemistry; D008099:Liver / Q000098:blood supply* / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D014909:Wheat Germ Agglutinins / Q000032:analysis
D015415:Biomarkers; D017077:Culture Media, Conditioned; D014909:Wheat Germ Agglutinins