MSCs inhibit monocyte-derived DC maturation and function by selectively interfering with the generation of immature DCs: central role of MSC-derived prostaglandin E2

Various studies analyzed the inhibitory effect exerted by mesenchymal stem cells (MSCs) on cells of the innate or acquired immunity. Myeloid dendritic cells (DCs) are also susceptible to such inhibition. In this study, we show that MSCs strongly inhibit DC generation from peripheral blood monocytes. In the presence of MSCs, monocytes supplemented with granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4) did not acquire the surface phenotype typical of immature (CD14(-), CD1a(+)) or mature (CD80(+), CD86(+), CD83(+)) DCs, failed to produce IL-12, and did not induce T-cell activation or proliferation. Analysis of the molecular mechanism(s) responsible for the inhibitory effect…