Abstract:Mesenchymal stem cells (MSCs) are multipotent stem cells that exist in many tissues and can be easily isolated from bone marrow， adipose tissue， umbilical cord. These isolated and in vitro expanded MSCs have been shown to differentiate into adipocytes， osteoblasts， chondrocytes， and possess strong immunosuppressive ability， bringing new hopes for the treatment of many diseases. Both exogenously administered MSCs and tissue-resident MSCs are found to migrate to damaged tissues， where they participate in tissue repair. Their communication with the inflammatory microenvironment is an essential part of this process. Not only do inflammatory cytokines endow MSCs with the immunosuppressive ability， but also inflammatory stimuli confer on MSCs the ability to suppress the immune response in some cases or to enhance it in others， depending on their type and intensity. Here we review the current findings on the interplay between MSCs and immune responses in disease pathogenesis and therapy.