The role of mesenchymal stem cells in hematopoiesis

Role of bone marrow macrophages in controlling homeostasis and repair in bone and bone marrow niches

“…Whole mount imaging of bone and BM provided additional evidence that quiescent HSC are enriched in the endosteal region adjacent to arterioles [62], while cycling/active HSC located near perisinusoidal niches where their greater metabolic demand is better served by higher oxygen content [59,60,62]. Within this hierarchy of niches (Figure 1), HSC are supported by specific stromal cells including mesenchymal stem/progenitor cells and pericytes (nestin + or leptin receptor + ), early committed osteolineage progenitors (osterix + cells), non-myelinating Schwann cells, sympathetic nerves and endothelial cells [69]. Macrophages also contribute to HSC niche homeostasis [16,28,70,71] and dissection of their specific niche functional contributions and molecular mediators is in its infancy [60].…”