Illustration of anti-inflammatory action of hMSCs mediated mainly through TSG-6. (1) Zymosan activated macrophages via TLR2. (2) Activated NF-κB increased the expression of pro-inflammatory cytokines. (3) HMSCs were activated by the pro-inflammatory cytokines to secrete TSG-6. (4) TSG-6 negatively regulated the TLR2-mediated responses through CD44.