Contribution of microRNAs to the immunosuppressive function of mesenchymal stem cells.

Mesenchymal stem/stromal cells (MSCs) are progenitor cells identified in many adult tissues, in particular in bone marrow or adipose tissue and, in placental tissues. MSCs exert pleiotropic functions that render them attractive for many clinical applications, both in degenerative and inflammatory diseases. Their main mode of action is through the secretion of trophic factors that can be released in the extracellular milieu or packaged within extracellular vesicles. These factors can be proteins, lipids, mRNAs or miRNAs that possess diverse effects, notably pro-angiogenic, anti-fibrotic, anti-apoptotic or anti-inflammatory. The anti-inflammatory role of a number of miRNAs has been demonstrated with different types of immune cells but few have been associated with the immunomodulatory function of MSCs. In this review, we summarize the data on the miRNAs that have been validated as participating to the anti-inflammatory role of MSCs.