Although an appropriate inflammatory microenvironment is indispensable for MSCs to exert immunosuppressive effects, an excessive inflammatory microenvironment, especially TNF‐α, reduces the immunosuppressive capacity of MSCs by inducing apoptosis.[34] The level of TNF‐α in plasma and synovial fluid increased in the RA microenvironments, reflecting disease activity. This evidence concerns the gene TNF and rheumatoid arthritis.