Sources of human and murine hematopoietic stem cells

This unit describes various sites from which human and murine hematopoietic stem cells (HSC) can be collected, including bone marrow, peripheral blood, and, in the case of human HSC, umbilical cord blood. Guidelines related to each of the cell harvesting procedures are described, and a discussion of the expected populations of cells harvested from these various sites is included. Cell products can be composed of a combination of true HSC, lineage-committed hematopoietic progenitor cells, and terminally differentiated fully mature cells. While use of steady-state peripheral blood as a source of HSC is the most convenient approach, yields of these cells are very low. However, mobilization methods that stimulate movement of stem cells out of the bone marrow into peripheral blood significantly increase HSC yields. Use of G-CSF has been accepted as the standard method for stem cell mobilization. The unit describes a variety of investigational cytokines and chemokines that have been shown to mobilize human stem including interleukin 3, 11, and 8, flt-3 ligand, and stem cell factor.