Mesenchymal stem cell niche. Mesenchymal stem cells (MSCs) are shown in their putative perivascular niche (BV, blood vessel), interacting with (1) various other differentiated cells (DC1, DC2, etc.) by means of cell-adhesion molecules, such as cadherins, (2) extracellular matrix (ECM) deposited by the niche cells mediated by integrin receptors, and (3) signaling molecules, which may include autocrine, paracrine, and endocrine factors. Another variable is O2 tension, with hypoxia associated with MSCs in the bone marrow niche.
Kolf et al. Arthritis Research & Therapy 2007 9:204 doi:10.1186/ar2116