Mesenchymal Stromal Cells and Toll-Like Receptor Priming: A Critical Review

Mesenchymal Stromal Cells (MSCs) are potential cellular candidates for several immunotherapy purposes. Their multilineage potential and immunomodulatory properties make them interesting tools for the treatment of various immunological diseases. However, depending on the local microenvironment, diverse biological functions of MSCs can be modulated. Indeed, during infections such as obtained following TLR-agonist engagement (called as TLR priming), the phenotype, multilineage potential, hematopoietic support and immunomodulatory capacity of MSCs can present critical changes, which could further affect their therapeutic potential. Thus, for appropriate clinical application of MSCs, it is important to well know and understand these effects in particular during infectious episodes and to find the suitable experimental settings to study that. Pre-stimulation of MSCs with a specific TLR ligand may serve as an effective priming step to modulate one of its function to achieve a desired therapeutic issue.