Immune regulation by mesenchymal stem cells: two sides to the coin.
Mesenchymal stem cells (MSCs) constitute a rare population of adult stem cells that can be isolated from a simple bone marrow aspirate in the absence of prior mobilization. For this reason, MSCs are particularly attractive for cell-based medicine. Ex-vivo-expanded MSCs isolated from different species, including human MSCs, have been shown to suppress the activity of a broad range of immune cells, including T cells, antigen-presenting cells, natural killer (NK) cells and B cells. New studies have further shown that MSCs interact with NK cells, express NK cell receptor ligands, express Toll-like receptors (TLRs), respond to TLR ligands and act as antigen-presenting cells upon interferon-gamma stimulation. Taken together, these studies suggest that MSCs may constitute a previously unrecognized player of the immune system with dichotomy of function reminiscent of other antigen-presenting cells. An important question that remains unanswered is whether resident MSCs actually play a role in endogenous immune responses? I here review the mechanisms of MSC-mediated immune regulation and discuss the major roles of resident MSCs in health and disease.
Stagg
J
J
Cancer Immunology Program, Sir Donald and Lady Trescowthick Laboratories, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia. john.stagg@petermac.org
D000818:Animals; D006801:Humans; D007107:Immune System / Q000166:cytology* / Q000502:physiology*; D059630:Mesenchymal Stem Cells / Q000276:immunology*