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Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis.

Lee J, Choi BI, Park SY, An SY, Han J, Kim JH - Exp. Mol. Med. (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Stem Cells and Tissue Regeneration, Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea.

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.

No MeSH data available.


Related in: MedlinePlus

Milk fat globule-EGF-factor 8 (MFG-E8) and CD34 expressions in the yolk sac blood island of developing mouse fetuses at embryonic day E10.5. (a) Hematoxylin and eosin (H&E) staining image of E10.5 mouse embryo. Decidua, spongial layer and labyrinth of the placenta are shown outside of the yolk sac surrounding the embryo. (b and c) Enlarged image of the area indicated with ‘*' in a are shown in b. High magnification of the boxed area in b are shown in c. Cells located in the yolk sac blood island are large and have prominent nuclei. (d–f) Immunofluorescent labeling of the blood island in the yolk sac with anti-CD34 and anti-MFG-E8 antibodies. Note that the CD34+ cell co-expressed MFG-E8. The boxed area in f are separately shown in g. White arrowhead indicates CD34− cells. Scale bars in: a=250 μm; b and f=50 μm, and c and g=10 μm.
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fig1: Milk fat globule-EGF-factor 8 (MFG-E8) and CD34 expressions in the yolk sac blood island of developing mouse fetuses at embryonic day E10.5. (a) Hematoxylin and eosin (H&E) staining image of E10.5 mouse embryo. Decidua, spongial layer and labyrinth of the placenta are shown outside of the yolk sac surrounding the embryo. (b and c) Enlarged image of the area indicated with ‘*' in a are shown in b. High magnification of the boxed area in b are shown in c. Cells located in the yolk sac blood island are large and have prominent nuclei. (d–f) Immunofluorescent labeling of the blood island in the yolk sac with anti-CD34 and anti-MFG-E8 antibodies. Note that the CD34+ cell co-expressed MFG-E8. The boxed area in f are separately shown in g. White arrowhead indicates CD34− cells. Scale bars in: a=250 μm; b and f=50 μm, and c and g=10 μm.

Mentions: During mouse embryogenesis, CD34 is expressed by HSCs in different tissues, including the yolk sac, AGM, placenta and fetal liver, but its expression decreases and disappears after birth.29, 30, 31, 32, 33, 34, 35, 36 To identify HSCs in hematopoietic tissues of staged mouse embryos, we used an HSC marker, CD34, to investigate the possible correlation between MFG-E8 and CD34 expression in different hematopoietic tissues. The yolk sac is the first site of primitive hematopoiesis in human and mouse embryos, and provides erythroid and myeloid cells during embryonic life.37 Hematoxylin and eosin staining of embryo sections showed that large cells with prominent nuclei were located in the yolk sac blood islands as aggregates in developing embryos (E10.5; Figures 1a–c). Immunohistochemical staining of consecutive sections of the yolk sac revealed that these cells expressed MFG-E8 (Figure 1d). Furthermore, strong expression of MFG-E8 was specifically detected in the CD34+ HSCs, which showed a high nuclei/cytoplasm ratio (Figures 1e–g). A few cells which did not express CD34 were negative for MFG-E8 immunostaining (Figure 1g, arrowhead).


Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis.

Lee J, Choi BI, Park SY, An SY, Han J, Kim JH - Exp. Mol. Med. (2015)

Milk fat globule-EGF-factor 8 (MFG-E8) and CD34 expressions in the yolk sac blood island of developing mouse fetuses at embryonic day E10.5. (a) Hematoxylin and eosin (H&E) staining image of E10.5 mouse embryo. Decidua, spongial layer and labyrinth of the placenta are shown outside of the yolk sac surrounding the embryo. (b and c) Enlarged image of the area indicated with ‘*' in a are shown in b. High magnification of the boxed area in b are shown in c. Cells located in the yolk sac blood island are large and have prominent nuclei. (d–f) Immunofluorescent labeling of the blood island in the yolk sac with anti-CD34 and anti-MFG-E8 antibodies. Note that the CD34+ cell co-expressed MFG-E8. The boxed area in f are separately shown in g. White arrowhead indicates CD34− cells. Scale bars in: a=250 μm; b and f=50 μm, and c and g=10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4525298&req=5

fig1: Milk fat globule-EGF-factor 8 (MFG-E8) and CD34 expressions in the yolk sac blood island of developing mouse fetuses at embryonic day E10.5. (a) Hematoxylin and eosin (H&E) staining image of E10.5 mouse embryo. Decidua, spongial layer and labyrinth of the placenta are shown outside of the yolk sac surrounding the embryo. (b and c) Enlarged image of the area indicated with ‘*' in a are shown in b. High magnification of the boxed area in b are shown in c. Cells located in the yolk sac blood island are large and have prominent nuclei. (d–f) Immunofluorescent labeling of the blood island in the yolk sac with anti-CD34 and anti-MFG-E8 antibodies. Note that the CD34+ cell co-expressed MFG-E8. The boxed area in f are separately shown in g. White arrowhead indicates CD34− cells. Scale bars in: a=250 μm; b and f=50 μm, and c and g=10 μm.
Mentions: During mouse embryogenesis, CD34 is expressed by HSCs in different tissues, including the yolk sac, AGM, placenta and fetal liver, but its expression decreases and disappears after birth.29, 30, 31, 32, 33, 34, 35, 36 To identify HSCs in hematopoietic tissues of staged mouse embryos, we used an HSC marker, CD34, to investigate the possible correlation between MFG-E8 and CD34 expression in different hematopoietic tissues. The yolk sac is the first site of primitive hematopoiesis in human and mouse embryos, and provides erythroid and myeloid cells during embryonic life.37 Hematoxylin and eosin staining of embryo sections showed that large cells with prominent nuclei were located in the yolk sac blood islands as aggregates in developing embryos (E10.5; Figures 1a–c). Immunohistochemical staining of consecutive sections of the yolk sac revealed that these cells expressed MFG-E8 (Figure 1d). Furthermore, strong expression of MFG-E8 was specifically detected in the CD34+ HSCs, which showed a high nuclei/cytoplasm ratio (Figures 1e–g). A few cells which did not express CD34 were negative for MFG-E8 immunostaining (Figure 1g, arrowhead).

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Stem Cells and Tissue Regeneration, Division of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea.

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.

No MeSH data available.


Related in: MedlinePlus