Initially, the RA model rats showed obviously enhanced limb swelling, increased FLS numbers and promoted inflammation in synovial tissues, and TNF‐α, IL‐6 and IL‐8 expression was notably enhanced both in vivo and in vitro; however, BM‐MSC‐derived Ev transfection reversed these symptoms in the RA model rats. The gene discussed is CXCL8; the disease is rheumatoid arthritis.