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. Author manuscript; available in PMC: 2017 Apr 1.
Published in final edited form as: Semin Perinatol. 2016 Jan 15;40(3):138–151. doi: 10.1053/j.semperi.2015.12.002

Figure. A schematic on the parallel actions of MSC treatment on injured lung or brain.

Figure

Tissue injury precipitates an inflammatory response by activating microglia and lung macrophages to a pro-inflammatory state (red icons). MSC transplantation restores homeostasis mainly though paracrine actions. Among such actions are the repression or reversal of the pro-inflammatory state, resulting in a shift in the balance towards an anti-inflammatory state (green icons). In the anti-inflammatory state, endogenous resident stem cells can repair tissue more efficiently. A possible parallel mechanism, as preliminary reports suggest, could be that MSC factors act directly on endogenous stem cells, mobilizing them to proliferate and differentiate. The main functional vector in the MSC secretome are extracellular vesicles, including exosomes, and the therapeutic effects of MSC treatment can be efficiently recapitulated by cell-free, exosomes-based treatment. (A): Biogenesis of exosomes in MSC multivesicular bodies (MVB) and release upon fusion of the MVB with the plasma membrane. (B): Uptake of MSC exosomes by a lung macrophage, and release of the exosomal cargo (X) into the recipient cell. N: nucleus.