Understanding the role of the microenvironment during definitive hemopoietic development

The role of CD44 in fetal and adult hematopoietic stem cell regulation

“…Migration is essential for fetal hematopoiesis as multiple sites allow different inductive signals from the microenvironments to support hematopoietic development. 66 We show that, in WT mice, FL SDF-1α concentration progressively decreased from E14.5, with HSC migrating from the FL to the BM after E16.5. The accumulated data in other in vivo and in vitro contexts, including the homing of HSC and progenitors to BM, 20 suggest this occurs due to a co-ordinated sequence of events including: 1) a polarized source of SDF-1 developing; 2) the cells producing projections extending towards the SDF-1, with cell-associated CD44 migrating into the projections; and 3) CD44 binding to an external source of hyaluronan and the cells undergoing trans-endothelial migration.…”

Immuno-metabolism and adipose tissue: The key role of hematopoietic stem cells

“…The interplay between these components predominantly keeps HSCs in a quiescent state, but can also accelerate mature blood cell replenishment in cases of urgent need, such as during infection or excessive blood loss. A great number of molecules described in the adult BM niche display functions as HSC regulators, overlapping in function or interacting with each other to modulate HSC behavior [36]. The discovery that perturbations of the HSC niche can lead to hematopoietic disorders, has outlined the crucial role of this niche in the control of HSC activity and thus on immune cell formation [37].…”

Concise Review: From Greenhouse to Garden: The Changing Soil of the Hematopoietic Stem Cell Microenvironment During Development

“…This information is particularly useful for identifying methods of generating HSCs from pluripotent stem cells. A recent review by Cao et al [1] examines the hematopoietic microenvironment throughout development with extensive coverage of the fetal liver (FL) and beyond. Here, we provide a complementary review concentrating on the earlier origins of HSCs in the aorta-gonadsmesonephros (AGM).…”