MSPCs, together with some sinusoidal endothelial cells, express soluble and membrane-bound SCF, CXCL12, and IL-7 that not only regulate HSC and MPP numbers, but also sustain lymphopoiesis. MSPCs in the bone marrow are mostly perisinusoidal cells that can differentiate into osteoblasts, osteocytes, chondrocytes and adipocytes. MSPC differentiation is coordinated with the downregulation of SCF, CXCL12 and IL-7 expression.