Normal 0 false false false EN-GB X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-ansi-language:EN-GB;} Mesenchymal stem cells (MSC) have induced expansive interest from both scientific and clinical points of view over the last decennium. This interest stems from the capacity of these cells to differentiate into multiple lineages and from their secretion of growth factors that can activate progenitor cells, which make MSC potentially applicable for tissue regenerative purposes. When exposed to inflammatory conditions, MSC furthermore exhibit immunosuppressive properties. The reduction of chronic or acute inflammatory responses by MSC may halt the development of injury and allow regenerative processes to take place. This prospective has initiated attempts to use MSC as an immunosuppressive and regenerative agent in transplantation and regeneration of tissues like kidney, liver, heart, bone and multiple others. Nevertheless, the conditions under which MSC therapy is effective and via what mechanisms MSC operate are, in particular in in vivo settings, not clear. The route of administration and the reigning immunological conditions are likely to be key for the efficacy of MSC. Studies have demonstrated for instance that MSC may be immunostimulatory under immunological quiescent conditions. Whereas some reports indicate that homing of MSC to inflamed tissues and their secretion of growth and anti-inflammatory factors are responsible for their effect, others show that MSC rapidly disappear after administration and may not have time to actively contribute to immunosuppression and tissue repair. Many aspects of MSC have to be clarified in order to develop efficient therapies. In this special topic, different views on the mechanisms of immunomodulation and regeneration by MSC and on the possible applications of MSC in transplantation and tissue regeneration will be put together.