RESUMO
Mesenchymal Stem Cells [MSCs] are well known as the regulator of the immune system. These multipotent non-hematopoietic progenitor cells have been originally isolated from bone marrow, and later on found in several other tissues, such as skeletal muscle, umbilical cord blood, adipose and fetal liver tissues. Immunomodulatory effects of MSCs on a variety of immune cells such as T and B lymphocytes, Natural Killer cells [NK], neutrophils, macrophages and dendritic cells, has made a good candidate of them for the treatment of inflammatory disorders, particularly autoimmune diseases such as multiple sclerosis and rheumatoid arthritis. In addition, several studies have indicated mechanisms by which MSCs could reduce immune cell proliferation and activation leading to immune tolerance induction. Since T lymphocytes are considered as the most important immune cells, effect of MSCs on the activity of these cells has a very special significance to direct immune response. Under various conditions, T- lymphocytes have different phenotype and performance and can be differentiated into particular subtype such as regulatory T cells. Both in vitro and in vivo studies have indicated that MSCs modulate innate and adaptive immune system by promoting generation of CD4+CD25+ T regulatory cells which have important role in immune tolerance induction and auto- immune disease prevention. MSCs are able to block pro-inflammatory and increase anti-inflammatory cytokines secretion. So such unique immunomodulatory features make MSCs ideal candidates for clinical application as immunosuppressants which can be considered for autoimmune diseases treatment. Therefore, in this short-review, we attempt to focus mainly on the existing information about MSCs in association with immunomodulatory function of them on the immune system. In addition, the possible mechanisms and the performance impact of MSCs in autoimmune diseases improvement are discussed here. However, increasing knowledge of how MSCs will influence on the immune system suppression, leading us to better use of these cells as a promising tool in the treatment of autoimmune diseases