CD166 regulates human and murine hematopoietic stem cells and the hematopoietic niche.

We previously showed that immature CD166(+) osteoblasts (OB) promote hematopoietic stem cell (HSC) function. Here, we demonstrate that CD166 is a functional HSC marker that identifies both murine and human long-term repopulating cells. Both murine LSKCD48(-)CD166(+)CD150(+) and LSKCD48(-)CD166(+)CD150(+)CD9(+) cells, as well as human Lin(-)CD34(+)CD38(-)CD49f(+)CD166(+) cells sustained significantly higher levels of chimerism in primary and secondary recipients than CD166(-) cells.

Differential stem- and progenitor-cell trafficking by prostaglandin E2.

To maintain lifelong production of blood cells, haematopoietic stem cells (HSCs) are tightly regulated by inherent programs and extrinsic regulatory signals received from their microenvironmental niche. Long-term repopulating HSCs reside in several, perhaps overlapping, niches that produce regulatory molecules and signals necessary for homeostasis and for increased output after stress or injury. Despite considerable advances in the specific cellular or molecular mechanisms governing HSC-niche interactions, little is known about the regulatory function in the intact mammalian haematopoietic niche.