Although various cytokines, growth factors, and chemokines are known to regulate @entity1210 , expansion of @entity1583 stem cells (HSCs) in vitro with the use of such agents has proved problematic. Stromal cells are major components of the microenvironment that surrounds @entity1583 cells and are thought to play an important role in @entity1210 in vivo. Co-culture of HSCs with stromal cells promotes @entity1210 and self-renewal of HSCs. Definitive @entity1583 cells first appear during @entity1 embryonic development in the aorta-gonad-mesonephros (AGM) region, and it is therefore thought that the microenvironment of this region plays an important role in HSC ontogeny. We have adopted two approaches to studying the contribution of the AGM microenvironment to @entity1210 . In the first approach, we have developed an in vitro culture system for @entity19 AGM explants. Hematopoiesis is enhanced in such cultures by the presence of the combination of @entity10898 ( @entity10898 ), basic fibroblast growth factor, @entity1778 inhibitory factor, and @entity28842 (SFLO culture). However, transplantation assays revealed that HSCs capable of long-term reconstitution of the @entity1583 compartment of irradiated @entity19 (LTR-HSCs) do not expand in AGM-SFLO cultures; rather, these cultures appear to provide a favorable microenvironment for hematogenic angioblasts that are precursors of both endothelial and @entity1583 cells. In our second approach, we have established various stromal cell lines from the @entity19 AGM region. The AGM-S3 cell line supports @entity1 and @entity19 primitive @entity1583 cells as well as @entity19 LTR-HSCs. Maintenance of LTR-HSCs is mediated by a mechanism other than @entity10898 signaling through its receptor ( @entity17777 ). These two in vitro approaches should prove useful for further elucidation of the mechanisms that underlie @entity1210 and HSC self-renewal.

Role of the microenvironment of the embryonic aorta-gonad-mesonephros region in XXXX .

@entity1 :: ('9606', 'Species') :: ['mammalian', 'human'] @entity10898 :: ('17311(Tax:10090)', 'Gene') :: ['stem cell factor', 'SCF'] @entity19 :: ('10090', 'Species') :: ['mice', 'mouse'] @entity17777 :: ('16590(Tax:10090)', 'Gene') :: ['c-Kit'] @entity1778 :: ('MESH:D007938', 'Disease') :: ['leukemia'] @entity1583 :: ('MESH:D019337', 'Disease') :: ['hematopoietic'] @entity28842 :: ('18413(Tax:10090)', 'Gene') :: ['oncostatin M'] @entity1210 :: ('MESH:C536227', 'Disease') :: ['hematopoiesis']
@entity1210 :: (MESH:C536227,Disease) :: ['hematopoiesis']
