Therapeutic effects of intravenously injected MSCs in an animal model of asthma. Reduced deposition of collagen and lower bronchoconstrictive index accompanied with reduced resistive and viscoelastic pressures were noticed in MSC-treated asthmatic animals. Transplanted MSCs altered the phenotype of antigen-specific CD4 T cells in asthmatic animals via MSC-derived extracellular vesicles (EVs). Additionally, MSCs reduced eosinophil infiltration and mucus production in the lungs and downregulated levels of Th2 cytokines (IL-4, IL-5, and IL-13) in bronchial lavage, as well as serum levels of IgG1 and IgE. Alveolar macrophages become alternatively activated and developed an anti-inflammatory and immunosuppressive M2 phenotype after phagocytosis of transplanted MSCs.