Along with TNF-α, IL-1β has been reported to have an essential role in RA pathogenesis.1, 32 Recently, increasing evidence has implicated the NLRP3 inflammasome-mediated IL-1β secretion in RA,23 and only a few groups have shown that MSCs could suppress the activation of NLRP3 inflammasomes in macrophages.33, 34 We thus investigated whether hUCB-MSCs could regulate the NLRP3 inflammasome. This evidence concerns the gene IL1B and rheumatoid arthritis.