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BioMed Research International
Volume 2014 (2014), Article ID 216806, 14 pages
http://dx.doi.org/10.1155/2014/216806
Review Article

Mechanisms of T-Cell Immunosuppression by Mesenchymal Stromal Cells: What Do We Know So Far?

1Faculty of Ceilandia, University of Brasilia, 72220-900 Brasilia, DF, Brazil
2Faculty of Health Sciences, University of Brasilia, 70910-900 Brasilia, DF, Brazil

Received 21 February 2014; Revised 15 May 2014; Accepted 31 May 2014; Published 16 June 2014

Academic Editor: Florian Toegel

Copyright © 2014 Rodrigo Haddad and Felipe Saldanha-Araujo. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Mesenchymal stromal cells (MSCs) are multipotent cells, which can give rise to several cell types including osteoblasts, adipocytes, and chondroblasts. These cells can be found in a variety of adult and fetal tissues, such as bone marrow, adipose tissue, cord blood, and placenta. In recent years, the biological properties of MSCs have attracted the attention of researchers worldwide due to their potential application for treating a series of clinical situations. Among these properties, special attention should be given to the immunoregulatory potential of those cells. MSCs are able to act on all cells of the immune system, which includes the capacity to inhibit the proliferation and function of T-cells. This feature renders them natural candidates to treat several diseases in which cellular immune response is exacerbated. In this review, we outline the main mechanisms by which MSCs immunosuppress T-cell response, focusing on cell-cell contact, secretion of soluble factors, and regulatory T-cell generation. The influence of surface markers in the immunosuppression process and features of MSCs isolated from different sources are also discussed. Finally, the influences of toll-like receptors and cytokines on the inflammatory microenvironment are highlighted regarding the activation of MSCs to exert their immunoregulatory function.