“…Generally, HSCs and other non-HSCs are actively chemoattracted by factors secreted by BM stroma cells and osteoblasts [e.g., stromal derived factor-1 (SDF-1), hepatocyte growth factor (HGF), and/or vascular endothelial growth factor (VEGF)] and colonize marrow by the end of the second and the beginning of the third trimester of gestation (Nagasawa, 2000). We envision that all these non-HSCs residing in the BM (e.g., VSELs) have some role in the homeostasis and turnover of peripheral tissues and, if needed, could be mobilized from the BM into circulation during tissue injury and stress (Figure 1 panel B), thereby facilitating the regeneration of damaged organs (Kollet et al, 2003;Kucia et al, 2004;Kucia et al, 2006a;Kucia et al, 2006b;Kucia et al, 2006c, Kucia et al 2008. Table II lists different types of non-HSCs that have been postulated to reside in BM tissue.…”