Figure 1.

Schematic representation of the interactions between mesenchymal stem cells and immune cells. After activation, mesenchymal stem cells secrete soluble mediators - such as nitric oxide (NO), prostaglandin (PGE₂), indoleamine 2,3-dioxygenase (IDO), IL-6, and human leukocyte antigen (HLA)-G. Production of these mediators regulates the proliferation and function of a variety of immune cells as well as the induction of regulatory T (T_REG) cells either directly or indirectly through the generation of immature dendritic cells (DC). NK, natural killer.