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Putative intermediate precursor between hematogenic endothelial cells and blood cells in the developing embryo.
Stuart T Fraser1, Minetaro Ogawa, Tomomasa Yokomizo
1Department of Molecular Genetics, Faculty of Medicine and Graduate School of Medicine, Kyoto University, Shogoin Kawaharacho 53, Sakyo-ku, Japan. sfraser@mail.uni-mainz.de
Development, Growth & Differentiation
|March 13, 2003
Summary
Researchers discovered a novel cell population expressing both vascular endothelial (VE)-cadherin and the hematopoietic marker CD45 during embryogenesis. This VE-cadherin+ CD45+ cell type may represent an intermediate in the transition from hemogenic endothelial cells to blood cells.
Area of Science:
- Developmental biology
- Hematopoiesis
- Endothelial cell biology
Background:
- Endothelial cells are known precursors of hematopoietic cells during embryogenesis.
- Vascular endothelial (VE)-cadherin is crucial for endothelial cell adhesion.
- The precise mechanism by which endothelial cells generate hematopoietic cells remains under investigation.
Purpose of the Study:
- To identify and characterize a novel cell population involved in the endothelial-to-hematopoietic transition.
- To investigate the properties of VE-cadherin expressing cells in embryonic development.
- To determine the hematopoietic potential of newly identified VE-cadherin+ CD45+ cells.
Main Methods:
- Identification of VE-cadherin+ CD45+ cells in embryonic tissues without enzymatic dissociation.
- Culture of isolated cells on OP9 stroma to assess endothelial colony formation.
- Analysis of hematopoietic differentiation potential (erythroid, myeloid, lymphoid) of isolated cells.
- Examination of this cell population in Runx1 null mutant embryos.
Main Results:
- A novel cell population co-expressing VE-cadherin and CD45 was identified in embryonic tissues.
- These VE-cadherin+ CD45+ cells did not form endothelial colonies in vitro, unlike enzymatically dissociated VE-cadherin+ cells.
- Isolated VE-cadherin+ CD45+ cells from 9.5 days post coitus embryos generated erythroid and myeloid cells, but not B lymphoid cells.
- This novel population was absent in Runx1 null mutant embryos.
Conclusions:
- A previously unrecognized VE-cadherin+ cell population exists during embryonic development.
- This population exhibits distinct characteristics compared to previously described hemogenic endothelial cells.
- The findings suggest that VE-cadherin+ CD45+ cells represent an intermediate stage in the hemogenic endothelial-to-blood cell transition.