Although RA-FLSs showed significantly higher expression levels of IL-6, IL-1, TNF-α and TNFR2 than the control groups, this difference was not observed following their differentiation into iPSCs and iPSC-CMs, suggesting that the inflammatory profiles are abolished during iPSC reprogramming and differentiation (Supplementary Figure 4). Here, TNF is linked to rheumatoid arthritis.