Bone metabolism and cardiovascular function update. Inter-communication between bone marrow hematopoiesis and skeletal/vascular network

Abstract

The hematopoiesis takes place in the bone marrow. Because bone marrow is the "marrow" of the bone, bone marrow does not exist without bone. The specialized microenvironment for hematopoietic stem cells (HSCs) to be appropriately functional is called "niche" . In the recent ten years since the bone-forming osteoblast was identified as a HSC niche, the entire mesenchymal lineage cells from mesenchymal stem cells to end-terminal osteocytes have been recognized as niche cells or niche-modulators. Among these, mesenchymal stem/progenitor cells are located at perivascular area. The very recent study showed the difference between arteriolar and sinusoidal niches. It is likely that the vascular network and the bone tissue are connected by the mesenchymal lineage cells as a complex of bone forming system, and HSCs utilize this complex as a series of niche.