title: Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis.
abstract: The milk fat globule-EGF-factor 8 protein (MFG-E8) has been identified in various tissues, where it has an important role in intercellular interactions, cellular migration, and neovascularization. Previous studies showed that MFG-E8 is expressed in different cell types under normal and pathophysiological conditions, but its expression in hematopoietic stem cells (HSCs) during hematopoiesis has not been reported. In the present study, we investigated MFG-E8 expression in multiple hematopoietic tissues at different stages of mouse embryogenesis. Using immunohistochemistry, we showed that MFG-E8 was specifically expressed in CD34(+) HSCs at all hematopoietic sites, including the yolk sac, aorta-gonad-mesonephros region, placenta and fetal liver, during embryogenesis. Fluorescence-activated cell sorting and polymerase chain reaction analyses demonstrated that CD34(+) cells, purified from the fetal liver, expressed additional HSC markers, c-Kit and Sca-1, and that these CD34(+) cells, but not CD34(-) cells, highly expressed MFG-E8. We also found that MFG-E8 was not expressed in HSCs in adult mouse bone marrow, and that its expression was confined to F4/80(+) macrophages. Together, this study demonstrates, for the first time, that MFG-8 is expressed in fetal HSC populations, and that MFG-E8 may have a role in embryonic hematopoiesis.
authors.affiliation: Laboratory of Stem Cells and Tissue Regeneration, Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea.
authors.forename: Jaehun
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Pathology, National Cancer Center, Gyeonggi-do, Korea.
authors.forename: Byung-il
authors.initials: BI
authors.lastname: Choi
authors.affiliation: Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea.
authors.forename: Seo Young
authors.initials: SY
authors.lastname: Park
authors.affiliation: Laboratory of Stem Cells and Tissue Regeneration, Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea.
authors.forename: Su Yeon
authors.initials: SY
authors.lastname: An
authors.affiliation: Laboratory of Stem Cells and Tissue Regeneration, Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea.
authors.forename: Jiyou
authors.initials: J
authors.lastname: Han
authors.affiliation: Laboratory of Stem Cells and Tissue Regeneration, Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea.
authors.forename: Jong-Hoon
authors.initials: JH
authors.lastname: Kim
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis*; D001853:Bone Marrow / Q000648:ultrastructure; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D008099:Liver / Q000196:embryology; D051379:Mice / Q000196:embryology*; D008894:Milk Proteins / Q000032:analysis*; D010929:Placentation; D011247:Pregnancy
chemical_list: D018952:Antigens, CD34; D000954:Antigens, Surface; C490919:Mfge8 protein, mouse; D008894:Milk Proteins