title: The influence of macrophages on mesenchymal stromal cell therapy: passive or aggressive agents?
abstract: Mesenchymal stromal cells (MSC) have emerged as promising cell therapies for multiple conditions based on demonstrations of their potent immunomodulatory and regenerative capacities in models of inflammatory disease. Understanding the effects of MSC on T cells has dominated the majority of work carried out in this field to date; recently, however, a number of studies have shown that the therapeutic effect of MSC requires the presence of macrophages. It is timely to review the mechanisms and manner by which MSC modulate macrophage populations in order to design more effective MSC therapies and clinical studies. A complex cross-talk exists through which MSC and macrophages communicate, a communication that is not controlled exclusively by MSC. Here, we examine the evidence that suggests that MSC not only respond to inflammatory macrophages and adjust their secretome accordingly, but also that macrophages respond to encounters with MSC, creating a feedback loop which contributes to the immune regulation observed following MSC therapy. Future studies examining the effects of MSC on macrophages should consider the antagonistic role that macrophages play in this exchange.
authors.affiliation: Institute of Immunology, Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland.
authors.forename: F
authors.initials: F
authors.lastname: Carty
authors.affiliation: Institute of Immunology, Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland.
authors.forename: B P
authors.initials: BP
authors.lastname: Mahon
authors.affiliation: Institute of Immunology, Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland.
authors.forename: K
authors.initials: K
authors.lastname: English
mesh_terms: D000818:Animals; D015415:Biomarkers; D002450:Cell Communication; D002454:Cell Differentiation; D064987:Cell- and Tissue-Based Therapy; D016207:Cytokines / Q000378:metabolism; D006801:Humans; D056747:Immunomodulation; D018836:Inflammation Mediators / Q000378:metabolism; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism*; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism*; D010641:Phenotype; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
chemical_list: D015415:Biomarkers; D016207:Cytokines; D018836:Inflammation Mediators
keywords: inflammation; macrophage; mesenchymal stem cells