Fig. 1.

Under the stimulating human umbilical cord-derived mesenchymal stromal cells (hUC-dMSCs) with different factors, the quantities and components of exosomes had changed. Then, the biological characteristics of target cells also have changed after received the exosomes. (a) In a normal situation, target cells receive microvesicles and exosomes released from MSCs. (b) Stimulating hUC-dMSCs with interferon (IFN)- g, there were in a simulated inflammatory microenvironment that can significantly increase the release of MSCs-exosomes. Then, it can enhance the immunomodulatory activity of hUC-discs and increase the proportion of CD4+, CD25+ and Foxp3+T cells in the entire regulatory T cells. (c) Stimulating hUC-dMSCs with lipopolysaccharide (LPS) can secrete more exosomes than untreated ones, and the exosome derived from them are rich in miRNA let-7b, which can induce macrophages to exhibit the anti-inflammatory M2 phenotype by the specific signal pathway