Hematopoiesis mesoderm

Rollins-Smith, L.A., and Blair, P., Contribution of ventral blood island mesoderm to hematopoiesis inpostmetamorphic and metamorphosis-inhibited Xenopus laevis, Dev. Biol., 142, 178, 1990. 

Transgenic Embryo Explant Culture Assay for Induction of Hematopoiesis by Non-Mesodermal Signals... 

We have demonstrated 4) that primitive (visceral) endoderm secretes diffusible signal(s) that are required for the initiation of hematopoiesis and vasculogenesis during embryogenesis. Induction of mesoderm precedes the cellular and molecular events reflected in the explant cultures (our unpublished results). A number of important questions remain unresolved ... 

Might the molecules responsible for respecification of cell fate observed in the reprogramming assay be distinct from those involved in activation of hematopoiesis from nascent posterior mesoderm in vfvol The induction (epiblast explant) assay presumably reflects what occurs in vivo, while the reprogramming (anterior ectoderm) assay reflects the potential activity of visceral endoderm signals. Anterior ectoderm is normally fated to form neurectoderm, not blood or endothelial cells. 

OP9 is a commonly used murine stromal cell line from the bone marrow which is deficient in M-CSF and known to support hematopoiesis (Nakano et al. 1994). Although the mechanism by which these cells support hematopoietic differentiation from ES cells is largely unclear, the importance of M-CSF deficiency was demonstrated when recombinant M-CSF reduced differentiation of ES cells into mesodermal cells and subsequent development to hematopoietic cells (Nakano et al. 1994). OP9 cells have been studied for generating HPCs as well as definitive hematopoietic lineages from ES ceUs (Suzuki and Nakano 2001 Kitajima et al. 2003 Schmitt et al. 2004 Umeda et al. 2004 Vieira and Cumano 2004 La Motte-Mohs et al. 2005). 

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