title: Recruited peripheral blood monocytes participate in the liver extramedullary hematopoietic milieu.
abstract: The hematopoietic microenvironment has been investigated and well defined in the bone marrow. However, there is a lack of studies on the extramedullary hematopoietic milieu such as in the liver, to which hematopoietic stem cells migrate and there commence hematopoiesis under pathological conditions such as bone marrow failure. We induced extramedullary hematopoiesis by phenylhydrazine in the adult mouse liver and investigated the immunohistochemical, ultrastructural, and molecular changes within this organ. Using an intravital lectin injection technique, we found numerous monocytes attached to the central vein prior to hematopoietic foci formation. These cells were later incorporated into the hematopoietic foci. An increase in the mRNA expressions of the monocyte attracting chemokine CCL-2 (MCP-1) was noted in the central vein region as well as in cells within the hematopoietic foci. Together with local liver components, we regard these monocytes as components of the extramedullary hematopoietic milieu. We conclude that the recruitment of extra-hepatic monocytes is an important event during extramedullary hematopoiesis in the liver and that these monocytes participate in the liver hematopoietic microenvironment.
authors.affiliation: Department of Anatomy and Developmental Biology, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nakamura-Ishizu
authors.forename: Shunichi
authors.initials: S
authors.lastname: Morikawa
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shimizu
authors.forename: Taichi
authors.initials: T
authors.lastname: Ezaki
mesh_terms: D000818:Animals; D002465:Cell Movement; D018925:Chemokines / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006411:Hematopoiesis, Extramedullary; D017403:In Situ Hybridization; D037102:Lectins / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009000:Monocytes / Q000166:cytology* / Q000378:metabolism / Q000637:transplantation; D012157:Mononuclear Phagocyte System / Q000166:cytology; D009930:Organic Chemicals / Q000378:metabolism; D019707:Receptors, Chemokine / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013194:Staining and Labeling
chemical_list: D018925:Chemokines; D037102:Lectins; D009930:Organic Chemicals; C070080:PKH 26; D019707:Receptors, Chemokine