Mesenchymal stem cells (MSCs) are character- ized as multipotent stromal cells with the capacity for both self-renewal and differentiation into mesodermal cell lineages. MSCs also have a fibroblast-like phenotype and can be isolated from several tissues. In recent years, researchers have found that MSCs secrete several soluble factors that exert immunosuppressive effects by modulating both innate (macrophages, dendritic and NK cells) and adaptive (B cells and CD4+ and CD8+ T cells) immune responses. MSCs have the potential to provide effective treatment for a wide range of diseases and can be used in several applications in regenerative medicine such as tissue repair and gene delivery. In addition, MSCs were among the first stem cells to be introduced into clinical practice. Interest- ingly, these cells can modulate the immune response by both inhibiting the maturation/differentiation of dendritic cells and by suppressing the activation and/or function of T and B lymphocytes and NK cells in several autoimmuneand inflammatory diseases. both umbilical cord and adipose tissue can provide an interesting alternative source of MSCs due their efficient potential for expansion and differentiation. In addition, the process of obtaining these cells is less invasive compared to classical bone marrow aspiration.MSCs and Immune Regulatory Properties MSCs are considered to be “immunologically privileged”, as they express a relatively small complement of the molecules that are required for fully activating T cells. These cells have reduced expression of both class I and II major histocompatibility complex (MHCs).